drivers/md/raid5.c

   1 /*
   2  * raid5.c : Multiple Devices driver for Linux
   3  *         Copyright (C) 1996, 1997 Ingo Molnar, Miguel de Icaza, Gadi Oxman
   4  *         Copyright (C) 1999, 2000 Ingo Molnar
   5  *         Copyright (C) 2002, 2003 H. Peter Anvin
   6  *
   7  * RAID-4/5/6 management functions.
   8  * Thanks to Penguin Computing for making the RAID-6 development possible
   9  * by donating a test server!
  10  *
  11  * This program is free software; you can redistribute it and/or modify
  12  * it under the terms of the GNU General Public License as published by
  13  * the Free Software Foundation; either version 2, or (at your option)
  14  * any later version.
  15  *
  16  * You should have received a copy of the GNU General Public License
  17  * (for example /usr/src/linux/COPYING); if not, write to the Free
  18  * Software Foundation, Inc., 675 Mass Ave, Cambridge, MA 02139, USA.
  19  */
  20
  21 /*
  22  * BITMAP UNPLUGGING:
  23  *
  24  * The sequencing for updating the bitmap reliably is a little
  25  * subtle (and I got it wrong the first time) so it deserves some
  26  * explanation.
  27  *
  28  * We group bitmap updates into batches.  Each batch has a number.
  29  * We may write out several batches at once, but that isn't very important.
  30  * conf->seq_write is the number of the last batch successfully written.
  31  * conf->seq_flush is the number of the last batch that was closed to
  32  *    new additions.
  33  * When we discover that we will need to write to any block in a stripe
  34  * (in add_stripe_bio) we update the in-memory bitmap and record in sh->bm_seq
  35  * the number of the batch it will be in. This is seq_flush+1.
  36  * When we are ready to do a write, if that batch hasn't been written yet,
  37  *   we plug the array and queue the stripe for later.
  38  * When an unplug happens, we increment bm_flush, thus closing the current
  39  *   batch.
  40  * When we notice that bm_flush > bm_write, we write out all pending updates
  41  * to the bitmap, and advance bm_write to where bm_flush was.
  42  * This may occasionally write a bit out twice, but is sure never to
  43  * miss any bits.
  44  */
  45
  46 #include <linux/blkdev.h>
  47 #include <linux/kthread.h>
  48 #include <linux/raid/pq.h>
  49 #include <linux/async_tx.h>
  50 #include <linux/module.h>
  51 #include <linux/async.h>
  52 #include <linux/seq_file.h>
  53 #include <linux/cpu.h>
  54 #include <linux/slab.h>
  55 #include <linux/ratelimit.h>
  56 #include <linux/nodemask.h>
  57 #include <trace/events/block.h>
  58
  59 #include "md.h"
  60 #include "raid5.h"
  61 #include "raid0.h"
  62 #include "bitmap.h"
  63
  64 #define cpu_to_group(cpu) cpu_to_node(cpu)
  65 #define ANY_GROUP NUMA_NO_NODE
  66
  67 static bool devices_handle_discard_safely = false;
  68 module_param(devices_handle_discard_safely, bool, 0644);
  69 MODULE_PARM_DESC(devices_handle_discard_safely,
  70                  "Set to Y if all devices in each array reliably return zeroes on reads from discarded regions");
  71 static struct workqueue_struct *raid5_wq;
  72 /*
  73  * Stripe cache
  74  */
  75
  76 #define NR_STRIPES              256
  77 #define STRIPE_SIZE             PAGE_SIZE
  78 #define STRIPE_SHIFT            (PAGE_SHIFT - 9)
  79 #define STRIPE_SECTORS          (STRIPE_SIZE>>9)
  80 #define IO_THRESHOLD            1
  81 #define BYPASS_THRESHOLD        1
  82 #define NR_HASH                 (PAGE_SIZE / sizeof(struct hlist_head))
  83 #define HASH_MASK               (NR_HASH - 1)
  84 #define MAX_STRIPE_BATCH        8
  85
  86 static inline struct hlist_head *stripe_hash(struct r5conf *conf, sector_t sect)
  87 {
  88         int hash = (sect >> STRIPE_SHIFT) & HASH_MASK;
  89         return &conf->stripe_hashtbl[hash];
  90 }
  91
  92 static inline int stripe_hash_locks_hash(sector_t sect)
  93 {
  94         return (sect >> STRIPE_SHIFT) & STRIPE_HASH_LOCKS_MASK;
  95 }
  96
  97 static inline void lock_device_hash_lock(struct r5conf *conf, int hash)
  98 {
  99         spin_lock_irq(conf->hash_locks + hash);
 100         spin_lock(&conf->device_lock);
 101 }
 102
 103 static inline void unlock_device_hash_lock(struct r5conf *conf, int hash)
 104 {
 105         spin_unlock(&conf->device_lock);
 106         spin_unlock_irq(conf->hash_locks + hash);
 107 }
 108
 109 static inline void lock_all_device_hash_locks_irq(struct r5conf *conf)
 110 {
 111         int i;
 112         local_irq_disable();
 113         spin_lock(conf->hash_locks);
 114         for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
 115                 spin_lock_nest_lock(conf->hash_locks + i, conf->hash_locks);
 116         spin_lock(&conf->device_lock);
 117 }
 118
 119 static inline void unlock_all_device_hash_locks_irq(struct r5conf *conf)
 120 {
 121         int i;
 122         spin_unlock(&conf->device_lock);
 123         for (i = NR_STRIPE_HASH_LOCKS; i; i--)
 124                 spin_unlock(conf->hash_locks + i - 1);
 125         local_irq_enable();
 126 }
 127
 128 /* bio's attached to a stripe+device for I/O are linked together in bi_sector
 129  * order without overlap.  There may be several bio's per stripe+device, and
 130  * a bio could span several devices.
 131  * When walking this list for a particular stripe+device, we must never proceed
 132  * beyond a bio that extends past this device, as the next bio might no longer
 133  * be valid.
 134  * This function is used to determine the 'next' bio in the list, given the sector
 135  * of the current stripe+device
 136  */
 137 static inline struct bio *r5_next_bio(struct bio *bio, sector_t sector)
 138 {
 139         int sectors = bio_sectors(bio);
 140         if (bio->bi_iter.bi_sector + sectors < sector + STRIPE_SECTORS)
 141                 return bio->bi_next;
 142         else
 143                 return NULL;
 144 }
 145
 146 /*
 147  * We maintain a biased count of active stripes in the bottom 16 bits of
 148  * bi_phys_segments, and a count of processed stripes in the upper 16 bits
 149  */
 150 static inline int raid5_bi_processed_stripes(struct bio *bio)
 151 {
 152         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 153         return (atomic_read(segments) >> 16) & 0xffff;
 154 }
 155
 156 static inline int raid5_dec_bi_active_stripes(struct bio *bio)
 157 {
 158         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 159         return atomic_sub_return(1, segments) & 0xffff;
 160 }
 161
 162 static inline void raid5_inc_bi_active_stripes(struct bio *bio)
 163 {
 164         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 165         atomic_inc(segments);
 166 }
 167
 168 static inline void raid5_set_bi_processed_stripes(struct bio *bio,
 169         unsigned int cnt)
 170 {
 171         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 172         int old, new;
 173
 174         do {
 175                 old = atomic_read(segments);
 176                 new = (old & 0xffff) | (cnt << 16);
 177         } while (atomic_cmpxchg(segments, old, new) != old);
 178 }
 179
 180 static inline void raid5_set_bi_stripes(struct bio *bio, unsigned int cnt)
 181 {
 182         atomic_t *segments = (atomic_t *)&bio->bi_phys_segments;
 183         atomic_set(segments, cnt);
 184 }
 185
 186 /* Find first data disk in a raid6 stripe */
 187 static inline int raid6_d0(struct stripe_head *sh)
 188 {
 189         if (sh->ddf_layout)
 190                 /* ddf always start from first device */
 191                 return 0;
 192         /* md starts just after Q block */
 193         if (sh->qd_idx == sh->disks - 1)
 194                 return 0;
 195         else
 196                 return sh->qd_idx + 1;
 197 }
 198 static inline int raid6_next_disk(int disk, int raid_disks)
 199 {
 200         disk++;
 201         return (disk < raid_disks) ? disk : 0;
 202 }
 203
 204 /* When walking through the disks in a raid5, starting at raid6_d0,
 205  * We need to map each disk to a 'slot', where the data disks are slot
 206  * 0 .. raid_disks-3, the parity disk is raid_disks-2 and the Q disk
 207  * is raid_disks-1.  This help does that mapping.
 208  */
 209 static int raid6_idx_to_slot(int idx, struct stripe_head *sh,
 210                              int *count, int syndrome_disks)
 211 {
 212         int slot = *count;
 213
 214         if (sh->ddf_layout)
 215                 (*count)++;
 216         if (idx == sh->pd_idx)
 217                 return syndrome_disks;
 218         if (idx == sh->qd_idx)
 219                 return syndrome_disks + 1;
 220         if (!sh->ddf_layout)
 221                 (*count)++;
 222         return slot;
 223 }
 224
 225 static void return_io(struct bio *return_bi)
 226 {
 227         struct bio *bi = return_bi;
 228         while (bi) {
 229
 230                 return_bi = bi->bi_next;
 231                 bi->bi_next = NULL;
 232                 bi->bi_iter.bi_size = 0;
 233                 trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
 234                                          bi, 0);
 235                 bio_endio(bi, 0);
 236                 bi = return_bi;
 237         }
 238 }
 239
 240 static void print_raid5_conf (struct r5conf *conf);
 241
 242 static int stripe_operations_active(struct stripe_head *sh)
 243 {
 244         return sh->check_state || sh->reconstruct_state ||
 245                test_bit(STRIPE_BIOFILL_RUN, &sh->state) ||
 246                test_bit(STRIPE_COMPUTE_RUN, &sh->state);
 247 }
 248
 249 static void raid5_wakeup_stripe_thread(struct stripe_head *sh)
 250 {
 251         struct r5conf *conf = sh->raid_conf;
 252         struct r5worker_group *group;
 253         int thread_cnt;
 254         int i, cpu = sh->cpu;
 255
 256         if (!cpu_online(cpu)) {
 257                 cpu = cpumask_any(cpu_online_mask);
 258                 sh->cpu = cpu;
 259         }
 260
 261         if (list_empty(&sh->lru)) {
 262                 struct r5worker_group *group;
 263                 group = conf->worker_groups + cpu_to_group(cpu);
 264                 list_add_tail(&sh->lru, &group->handle_list);
 265                 group->stripes_cnt++;
 266                 sh->group = group;
 267         }
 268
 269         if (conf->worker_cnt_per_group == 0) {
 270                 md_wakeup_thread(conf->mddev->thread);
 271                 return;
 272         }
 273
 274         group = conf->worker_groups + cpu_to_group(sh->cpu);
 275
 276         group->workers[0].working = true;
 277         /* at least one worker should run to avoid race */
 278         queue_work_on(sh->cpu, raid5_wq, &group->workers[0].work);
 279
 280         thread_cnt = group->stripes_cnt / MAX_STRIPE_BATCH - 1;
 281         /* wakeup more workers */
 282         for (i = 1; i < conf->worker_cnt_per_group && thread_cnt > 0; i++) {
 283                 if (group->workers[i].working == false) {
 284                         group->workers[i].working = true;
 285                         queue_work_on(sh->cpu, raid5_wq,
 286                                       &group->workers[i].work);
 287                         thread_cnt--;
 288                 }
 289         }
 290 }
 291
 292 static void do_release_stripe(struct r5conf *conf, struct stripe_head *sh,
 293                               struct list_head *temp_inactive_list)
 294 {
 295         BUG_ON(!list_empty(&sh->lru));
 296         BUG_ON(atomic_read(&conf->active_stripes)==0);
 297         if (test_bit(STRIPE_HANDLE, &sh->state)) {
 298                 if (test_bit(STRIPE_DELAYED, &sh->state) &&
 299                     !test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) {
 300                         list_add_tail(&sh->lru, &conf->delayed_list);
 301                         if (atomic_read(&conf->preread_active_stripes)
 302                             < IO_THRESHOLD)
 303                                 md_wakeup_thread(conf->mddev->thread);
 304                 } else if (test_bit(STRIPE_BIT_DELAY, &sh->state) &&
 305                            sh->bm_seq - conf->seq_write > 0)
 306                         list_add_tail(&sh->lru, &conf->bitmap_list);
 307                 else {
 308                         clear_bit(STRIPE_DELAYED, &sh->state);
 309                         clear_bit(STRIPE_BIT_DELAY, &sh->state);
 310                         if (conf->worker_cnt_per_group == 0) {
 311                                 list_add_tail(&sh->lru, &conf->handle_list);
 312                         } else {
 313                                 raid5_wakeup_stripe_thread(sh);
 314                                 return;
 315                         }
 316                 }
 317                 md_wakeup_thread(conf->mddev->thread);
 318         } else {
 319                 BUG_ON(stripe_operations_active(sh));
 320                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
 321                         if (atomic_dec_return(&conf->preread_active_stripes)
 322                             < IO_THRESHOLD)
 323                                 md_wakeup_thread(conf->mddev->thread);
 324                 atomic_dec(&conf->active_stripes);
 325                 if (!test_bit(STRIPE_EXPANDING, &sh->state))
 326                         list_add_tail(&sh->lru, temp_inactive_list);
 327         }
 328 }
 329
 330 static void __release_stripe(struct r5conf *conf, struct stripe_head *sh,
 331                              struct list_head *temp_inactive_list)
 332 {
 333         if (atomic_dec_and_test(&sh->count))
 334                 do_release_stripe(conf, sh, temp_inactive_list);
 335 }
 336
 337 /*
 338  * @hash could be NR_STRIPE_HASH_LOCKS, then we have a list of inactive_list
 339  *
 340  * Be careful: Only one task can add/delete stripes from temp_inactive_list at
 341  * given time. Adding stripes only takes device lock, while deleting stripes
 342  * only takes hash lock.
 343  */
 344 static void release_inactive_stripe_list(struct r5conf *conf,
 345                                          struct list_head *temp_inactive_list,
 346                                          int hash)
 347 {
 348         int size;
 349         bool do_wakeup = false;
 350         unsigned long flags;
 351
 352         if (hash == NR_STRIPE_HASH_LOCKS) {
 353                 size = NR_STRIPE_HASH_LOCKS;
 354                 hash = NR_STRIPE_HASH_LOCKS - 1;
 355         } else
 356                 size = 1;
 357         while (size) {
 358                 struct list_head *list = &temp_inactive_list[size - 1];
 359
 360                 /*
 361                  * We don't hold any lock here yet, get_active_stripe() might
 362                  * remove stripes from the list
 363                  */
 364                 if (!list_empty_careful(list)) {
 365                         spin_lock_irqsave(conf->hash_locks + hash, flags);
 366                         if (list_empty(conf->inactive_list + hash) &&
 367                             !list_empty(list))
 368                                 atomic_dec(&conf->empty_inactive_list_nr);
 369                         list_splice_tail_init(list, conf->inactive_list + hash);
 370                         do_wakeup = true;
 371                         spin_unlock_irqrestore(conf->hash_locks + hash, flags);
 372                 }
 373                 size--;
 374                 hash--;
 375         }
 376
 377         if (do_wakeup) {
 378                 wake_up(&conf->wait_for_stripe);
 379                 if (conf->retry_read_aligned)
 380                         md_wakeup_thread(conf->mddev->thread);
 381         }
 382 }
 383
 384 /* should hold conf->device_lock already */
 385 static int release_stripe_list(struct r5conf *conf,
 386                                struct list_head *temp_inactive_list)
 387 {
 388         struct stripe_head *sh;
 389         int count = 0;
 390         struct llist_node *head;
 391
 392         head = llist_del_all(&conf->released_stripes);
 393         head = llist_reverse_order(head);
 394         while (head) {
 395                 int hash;
 396
 397                 sh = llist_entry(head, struct stripe_head, release_list);
 398                 head = llist_next(head);
 399                 /* sh could be readded after STRIPE_ON_RELEASE_LIST is cleard */
 400                 smp_mb();
 401                 clear_bit(STRIPE_ON_RELEASE_LIST, &sh->state);
 402                 /*
 403                  * Don't worry the bit is set here, because if the bit is set
 404                  * again, the count is always > 1. This is true for
 405                  * STRIPE_ON_UNPLUG_LIST bit too.
 406                  */
 407                 hash = sh->hash_lock_index;
 408                 __release_stripe(conf, sh, &temp_inactive_list[hash]);
 409                 count++;
 410         }
 411
 412         return count;
 413 }
 414
 415 static void release_stripe(struct stripe_head *sh)
 416 {
 417         struct r5conf *conf = sh->raid_conf;
 418         unsigned long flags;
 419         struct list_head list;
 420         int hash;
 421         bool wakeup;
 422
 423         /* Avoid release_list until the last reference.
 424          */
 425         if (atomic_add_unless(&sh->count, -1, 1))
 426                 return;
 427
 428         if (unlikely(!conf->mddev->thread) ||
 429                 test_and_set_bit(STRIPE_ON_RELEASE_LIST, &sh->state))
 430                 goto slow_path;
 431         wakeup = llist_add(&sh->release_list, &conf->released_stripes);
 432         if (wakeup)
 433                 md_wakeup_thread(conf->mddev->thread);
 434         return;
 435 slow_path:
 436         local_irq_save(flags);
 437         /* we are ok here if STRIPE_ON_RELEASE_LIST is set or not */
 438         if (atomic_dec_and_lock(&sh->count, &conf->device_lock)) {
 439                 INIT_LIST_HEAD(&list);
 440                 hash = sh->hash_lock_index;
 441                 do_release_stripe(conf, sh, &list);
 442                 spin_unlock(&conf->device_lock);
 443                 release_inactive_stripe_list(conf, &list, hash);
 444         }
 445         local_irq_restore(flags);
 446 }
 447
 448 static inline void remove_hash(struct stripe_head *sh)
 449 {
 450         pr_debug("remove_hash(), stripe %llu\n",
 451                 (unsigned long long)sh->sector);
 452
 453         hlist_del_init(&sh->hash);
 454 }
 455
 456 static inline void insert_hash(struct r5conf *conf, struct stripe_head *sh)
 457 {
 458         struct hlist_head *hp = stripe_hash(conf, sh->sector);
 459
 460         pr_debug("insert_hash(), stripe %llu\n",
 461                 (unsigned long long)sh->sector);
 462
 463         hlist_add_head(&sh->hash, hp);
 464 }
 465
 466 /* find an idle stripe, make sure it is unhashed, and return it. */
 467 static struct stripe_head *get_free_stripe(struct r5conf *conf, int hash)
 468 {
 469         struct stripe_head *sh = NULL;
 470         struct list_head *first;
 471
 472         if (list_empty(conf->inactive_list + hash))
 473                 goto out;
 474         first = (conf->inactive_list + hash)->next;
 475         sh = list_entry(first, struct stripe_head, lru);
 476         list_del_init(first);
 477         remove_hash(sh);
 478         atomic_inc(&conf->active_stripes);
 479         BUG_ON(hash != sh->hash_lock_index);
 480         if (list_empty(conf->inactive_list + hash))
 481                 atomic_inc(&conf->empty_inactive_list_nr);
 482 out:
 483         return sh;
 484 }
 485
 486 static void shrink_buffers(struct stripe_head *sh)
 487 {
 488         struct page *p;
 489         int i;
 490         int num = sh->raid_conf->pool_size;
 491
 492         for (i = 0; i < num ; i++) {
 493                 WARN_ON(sh->dev[i].page != sh->dev[i].orig_page);
 494                 p = sh->dev[i].page;
 495                 if (!p)
 496                         continue;
 497                 sh->dev[i].page = NULL;
 498                 put_page(p);
 499         }
 500 }
 501
 502 static int grow_buffers(struct stripe_head *sh)
 503 {
 504         int i;
 505         int num = sh->raid_conf->pool_size;
 506
 507         for (i = 0; i < num; i++) {
 508                 struct page *page;
 509
 510                 if (!(page = alloc_page(GFP_KERNEL))) {
 511                         return 1;
 512                 }
 513                 sh->dev[i].page = page;
 514                 sh->dev[i].orig_page = page;
 515         }
 516         return 0;
 517 }
 518
 519 static void raid5_build_block(struct stripe_head *sh, int i, int previous);
 520 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
 521                             struct stripe_head *sh);
 522
 523 static void init_stripe(struct stripe_head *sh, sector_t sector, int previous)
 524 {
 525         struct r5conf *conf = sh->raid_conf;
 526         int i, seq;
 527
 528         BUG_ON(atomic_read(&sh->count) != 0);
 529         BUG_ON(test_bit(STRIPE_HANDLE, &sh->state));
 530         BUG_ON(stripe_operations_active(sh));
 531
 532         pr_debug("init_stripe called, stripe %llu\n",
 533                 (unsigned long long)sector);
 534 retry:
 535         seq = read_seqcount_begin(&conf->gen_lock);
 536         sh->generation = conf->generation - previous;
 537         sh->disks = previous ? conf->previous_raid_disks : conf->raid_disks;
 538         sh->sector = sector;
 539         stripe_set_idx(sector, conf, previous, sh);
 540         sh->state = 0;
 541
 542         for (i = sh->disks; i--; ) {
 543                 struct r5dev *dev = &sh->dev[i];
 544
 545                 if (dev->toread || dev->read || dev->towrite || dev->written ||
 546                     test_bit(R5_LOCKED, &dev->flags)) {
 547                         printk(KERN_ERR "sector=%llx i=%d %p %p %p %p %d\n",
 548                                (unsigned long long)sh->sector, i, dev->toread,
 549                                dev->read, dev->towrite, dev->written,
 550                                test_bit(R5_LOCKED, &dev->flags));
 551                         WARN_ON(1);
 552                 }
 553                 dev->flags = 0;
 554                 raid5_build_block(sh, i, previous);
 555         }
 556         if (read_seqcount_retry(&conf->gen_lock, seq))
 557                 goto retry;
 558         insert_hash(conf, sh);
 559         sh->cpu = smp_processor_id();
 560 }
 561
 562 static struct stripe_head *__find_stripe(struct r5conf *conf, sector_t sector,
 563                                          short generation)
 564 {
 565         struct stripe_head *sh;
 566
 567         pr_debug("__find_stripe, sector %llu\n", (unsigned long long)sector);
 568         hlist_for_each_entry(sh, stripe_hash(conf, sector), hash)
 569                 if (sh->sector == sector && sh->generation == generation)
 570                         return sh;
 571         pr_debug("__stripe %llu not in cache\n", (unsigned long long)sector);
 572         return NULL;
 573 }
 574
 575 /*
 576  * Need to check if array has failed when deciding whether to:
 577  *  - start an array
 578  *  - remove non-faulty devices
 579  *  - add a spare
 580  *  - allow a reshape
 581  * This determination is simple when no reshape is happening.
 582  * However if there is a reshape, we need to carefully check
 583  * both the before and after sections.
 584  * This is because some failed devices may only affect one
 585  * of the two sections, and some non-in_sync devices may
 586  * be insync in the section most affected by failed devices.
 587  */
 588 static int calc_degraded(struct r5conf *conf)
 589 {
 590         int degraded, degraded2;
 591         int i;
 592
 593         rcu_read_lock();
 594         degraded = 0;
 595         for (i = 0; i < conf->previous_raid_disks; i++) {
 596                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 597                 if (rdev && test_bit(Faulty, &rdev->flags))
 598                         rdev = rcu_dereference(conf->disks[i].replacement);
 599                 if (!rdev || test_bit(Faulty, &rdev->flags))
 600                         degraded++;
 601                 else if (test_bit(In_sync, &rdev->flags))
 602                         ;
 603                 else
 604                         /* not in-sync or faulty.
 605                          * If the reshape increases the number of devices,
 606                          * this is being recovered by the reshape, so
 607                          * this 'previous' section is not in_sync.
 608                          * If the number of devices is being reduced however,
 609                          * the device can only be part of the array if
 610                          * we are reverting a reshape, so this section will
 611                          * be in-sync.
 612                          */
 613                         if (conf->raid_disks >= conf->previous_raid_disks)
 614                                 degraded++;
 615         }
 616         rcu_read_unlock();
 617         if (conf->raid_disks == conf->previous_raid_disks)
 618                 return degraded;
 619         rcu_read_lock();
 620         degraded2 = 0;
 621         for (i = 0; i < conf->raid_disks; i++) {
 622                 struct md_rdev *rdev = rcu_dereference(conf->disks[i].rdev);
 623                 if (rdev && test_bit(Faulty, &rdev->flags))
 624                         rdev = rcu_dereference(conf->disks[i].replacement);
 625                 if (!rdev || test_bit(Faulty, &rdev->flags))
 626                         degraded2++;
 627                 else if (test_bit(In_sync, &rdev->flags))
 628                         ;
 629                 else
 630                         /* not in-sync or faulty.
 631                          * If reshape increases the number of devices, this
 632                          * section has already been recovered, else it
 633                          * almost certainly hasn't.
 634                          */
 635                         if (conf->raid_disks <= conf->previous_raid_disks)
 636                                 degraded2++;
 637         }
 638         rcu_read_unlock();
 639         if (degraded2 > degraded)
 640                 return degraded2;
 641         return degraded;
 642 }
 643
 644 static int has_failed(struct r5conf *conf)
 645 {
 646         int degraded;
 647
 648         if (conf->mddev->reshape_position == MaxSector)
 649                 return conf->mddev->degraded > conf->max_degraded;
 650
 651         degraded = calc_degraded(conf);
 652         if (degraded > conf->max_degraded)
 653                 return 1;
 654         return 0;
 655 }
 656
 657 static struct stripe_head *
 658 get_active_stripe(struct r5conf *conf, sector_t sector,
 659                   int previous, int noblock, int noquiesce)
 660 {
 661         struct stripe_head *sh;
 662         int hash = stripe_hash_locks_hash(sector);
 663
 664         pr_debug("get_stripe, sector %llu\n", (unsigned long long)sector);
 665
 666         spin_lock_irq(conf->hash_locks + hash);
 667
 668         do {
 669                 wait_event_lock_irq(conf->wait_for_stripe,
 670                                     conf->quiesce == 0 || noquiesce,
 671                                     *(conf->hash_locks + hash));
 672                 sh = __find_stripe(conf, sector, conf->generation - previous);
 673                 if (!sh) {
 674                         if (!conf->inactive_blocked)
 675                                 sh = get_free_stripe(conf, hash);
 676                         if (noblock && sh == NULL)
 677                                 break;
 678                         if (!sh) {
 679                                 conf->inactive_blocked = 1;
 680                                 wait_event_lock_irq(
 681                                         conf->wait_for_stripe,
 682                                         !list_empty(conf->inactive_list + hash) &&
 683                                         (atomic_read(&conf->active_stripes)
 684                                          < (conf->max_nr_stripes * 3 / 4)
 685                                          || !conf->inactive_blocked),
 686                                         *(conf->hash_locks + hash));
 687                                 conf->inactive_blocked = 0;
 688                         } else {
 689                                 init_stripe(sh, sector, previous);
 690                                 atomic_inc(&sh->count);
 691                         }
 692                 } else if (!atomic_inc_not_zero(&sh->count)) {
 693                         spin_lock(&conf->device_lock);
 694                         if (!atomic_read(&sh->count)) {
 695                                 if (!test_bit(STRIPE_HANDLE, &sh->state))
 696                                         atomic_inc(&conf->active_stripes);
 697                                 BUG_ON(list_empty(&sh->lru) &&
 698                                        !test_bit(STRIPE_EXPANDING, &sh->state));
 699                                 list_del_init(&sh->lru);
 700                                 if (sh->group) {
 701                                         sh->group->stripes_cnt--;
 702                                         sh->group = NULL;
 703                                 }
 704                         }
 705                         atomic_inc(&sh->count);
 706                         spin_unlock(&conf->device_lock);
 707                 }
 708         } while (sh == NULL);
 709
 710         spin_unlock_irq(conf->hash_locks + hash);
 711         return sh;
 712 }
 713
 714 /* Determine if 'data_offset' or 'new_data_offset' should be used
 715  * in this stripe_head.
 716  */
 717 static int use_new_offset(struct r5conf *conf, struct stripe_head *sh)
 718 {
 719         sector_t progress = conf->reshape_progress;
 720         /* Need a memory barrier to make sure we see the value
 721          * of conf->generation, or ->data_offset that was set before
 722          * reshape_progress was updated.
 723          */
 724         smp_rmb();
 725         if (progress == MaxSector)
 726                 return 0;
 727         if (sh->generation == conf->generation - 1)
 728                 return 0;
 729         /* We are in a reshape, and this is a new-generation stripe,
 730          * so use new_data_offset.
 731          */
 732         return 1;
 733 }
 734
 735 static void
 736 raid5_end_read_request(struct bio *bi, int error);
 737 static void
 738 raid5_end_write_request(struct bio *bi, int error);
 739
 740 static void ops_run_io(struct stripe_head *sh, struct stripe_head_state *s)
 741 {
 742         struct r5conf *conf = sh->raid_conf;
 743         int i, disks = sh->disks;
 744
 745         might_sleep();
 746
 747         for (i = disks; i--; ) {
 748                 int rw;
 749                 int replace_only = 0;
 750                 struct bio *bi, *rbi;
 751                 struct md_rdev *rdev, *rrdev = NULL;
 752                 if (test_and_clear_bit(R5_Wantwrite, &sh->dev[i].flags)) {
 753                         if (test_and_clear_bit(R5_WantFUA, &sh->dev[i].flags))
 754                                 rw = WRITE_FUA;
 755                         else
 756                                 rw = WRITE;
 757                         if (test_bit(R5_Discard, &sh->dev[i].flags))
 758                                 rw |= REQ_DISCARD;
 759                 } else if (test_and_clear_bit(R5_Wantread, &sh->dev[i].flags))
 760                         rw = READ;
 761                 else if (test_and_clear_bit(R5_WantReplace,
 762                                             &sh->dev[i].flags)) {
 763                         rw = WRITE;
 764                         replace_only = 1;
 765                 } else
 766                         continue;
 767                 if (test_and_clear_bit(R5_SyncIO, &sh->dev[i].flags))
 768                         rw |= REQ_SYNC;
 769
 770                 bi = &sh->dev[i].req;
 771                 rbi = &sh->dev[i].rreq; /* For writing to replacement */
 772
 773                 rcu_read_lock();
 774                 rrdev = rcu_dereference(conf->disks[i].replacement);
 775                 smp_mb(); /* Ensure that if rrdev is NULL, rdev won't be */
 776                 rdev = rcu_dereference(conf->disks[i].rdev);
 777                 if (!rdev) {
 778                         rdev = rrdev;
 779                         rrdev = NULL;
 780                 }
 781                 if (rw & WRITE) {
 782                         if (replace_only)
 783                                 rdev = NULL;
 784                         if (rdev == rrdev)
 785                                 /* We raced and saw duplicates */
 786                                 rrdev = NULL;
 787                 } else {
 788                         if (test_bit(R5_ReadRepl, &sh->dev[i].flags) && rrdev)
 789                                 rdev = rrdev;
 790                         rrdev = NULL;
 791                 }
 792
 793                 if (rdev && test_bit(Faulty, &rdev->flags))
 794                         rdev = NULL;
 795                 if (rdev)
 796                         atomic_inc(&rdev->nr_pending);
 797                 if (rrdev && test_bit(Faulty, &rrdev->flags))
 798                         rrdev = NULL;
 799                 if (rrdev)
 800                         atomic_inc(&rrdev->nr_pending);
 801                 rcu_read_unlock();
 802
 803                 /* We have already checked bad blocks for reads.  Now
 804                  * need to check for writes.  We never accept write errors
 805                  * on the replacement, so we don't to check rrdev.
 806                  */
 807                 while ((rw & WRITE) && rdev &&
 808                        test_bit(WriteErrorSeen, &rdev->flags)) {
 809                         sector_t first_bad;
 810                         int bad_sectors;
 811                         int bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
 812                                               &first_bad, &bad_sectors);
 813                         if (!bad)
 814                                 break;
 815
 816                         if (bad < 0) {
 817                                 set_bit(BlockedBadBlocks, &rdev->flags);
 818                                 if (!conf->mddev->external &&
 819                                     conf->mddev->flags) {
 820                                         /* It is very unlikely, but we might
 821                                          * still need to write out the
 822                                          * bad block log - better give it
 823                                          * a chance*/
 824                                         md_check_recovery(conf->mddev);
 825                                 }
 826                                 /*
 827                                  * Because md_wait_for_blocked_rdev
 828                                  * will dec nr_pending, we must
 829                                  * increment it first.
 830                                  */
 831                                 atomic_inc(&rdev->nr_pending);
 832                                 md_wait_for_blocked_rdev(rdev, conf->mddev);
 833                         } else {
 834                                 /* Acknowledged bad block - skip the write */
 835                                 rdev_dec_pending(rdev, conf->mddev);
 836                                 rdev = NULL;
 837                         }
 838                 }
 839
 840                 if (rdev) {
 841                         if (s->syncing || s->expanding || s->expanded
 842                             || s->replacing)
 843                                 md_sync_acct(rdev->bdev, STRIPE_SECTORS);
 844
 845                         set_bit(STRIPE_IO_STARTED, &sh->state);
 846
 847                         bio_reset(bi);
 848                         bi->bi_bdev = rdev->bdev;
 849                         bi->bi_rw = rw;
 850                         bi->bi_end_io = (rw & WRITE)
 851                                 ? raid5_end_write_request
 852                                 : raid5_end_read_request;
 853                         bi->bi_private = sh;
 854
 855                         pr_debug("%s: for %llu schedule op %ld on disc %d\n",
 856                                 __func__, (unsigned long long)sh->sector,
 857                                 bi->bi_rw, i);
 858                         atomic_inc(&sh->count);
 859                         if (use_new_offset(conf, sh))
 860                                 bi->bi_iter.bi_sector = (sh->sector
 861                                                  + rdev->new_data_offset);
 862                         else
 863                                 bi->bi_iter.bi_sector = (sh->sector
 864                                                  + rdev->data_offset);
 865                         if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
 866                                 bi->bi_rw |= REQ_NOMERGE;
 867
 868                         if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
 869                                 WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
 870                         sh->dev[i].vec.bv_page = sh->dev[i].page;
 871                         bi->bi_vcnt = 1;
 872                         bi->bi_io_vec[0].bv_len = STRIPE_SIZE;
 873                         bi->bi_io_vec[0].bv_offset = 0;
 874                         bi->bi_iter.bi_size = STRIPE_SIZE;
 875                         /*
 876                          * If this is discard request, set bi_vcnt 0. We don't
 877                          * want to confuse SCSI because SCSI will replace payload
 878                          */
 879                         if (rw & REQ_DISCARD)
 880                                 bi->bi_vcnt = 0;
 881                         if (rrdev)
 882                                 set_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags);
 883
 884                         if (conf->mddev->gendisk)
 885                                 trace_block_bio_remap(bdev_get_queue(bi->bi_bdev),
 886                                                       bi, disk_devt(conf->mddev->gendisk),
 887                                                       sh->dev[i].sector);
 888                         generic_make_request(bi);
 889                 }
 890                 if (rrdev) {
 891                         if (s->syncing || s->expanding || s->expanded
 892                             || s->replacing)
 893                                 md_sync_acct(rrdev->bdev, STRIPE_SECTORS);
 894
 895                         set_bit(STRIPE_IO_STARTED, &sh->state);
 896
 897                         bio_reset(rbi);
 898                         rbi->bi_bdev = rrdev->bdev;
 899                         rbi->bi_rw = rw;
 900                         BUG_ON(!(rw & WRITE));
 901                         rbi->bi_end_io = raid5_end_write_request;
 902                         rbi->bi_private = sh;
 903
 904                         pr_debug("%s: for %llu schedule op %ld on "
 905                                  "replacement disc %d\n",
 906                                 __func__, (unsigned long long)sh->sector,
 907                                 rbi->bi_rw, i);
 908                         atomic_inc(&sh->count);
 909                         if (use_new_offset(conf, sh))
 910                                 rbi->bi_iter.bi_sector = (sh->sector
 911                                                   + rrdev->new_data_offset);
 912                         else
 913                                 rbi->bi_iter.bi_sector = (sh->sector
 914                                                   + rrdev->data_offset);
 915                         if (test_bit(R5_SkipCopy, &sh->dev[i].flags))
 916                                 WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
 917                         sh->dev[i].rvec.bv_page = sh->dev[i].page;
 918                         rbi->bi_vcnt = 1;
 919                         rbi->bi_io_vec[0].bv_len = STRIPE_SIZE;
 920                         rbi->bi_io_vec[0].bv_offset = 0;
 921                         rbi->bi_iter.bi_size = STRIPE_SIZE;
 922                         /*
 923                          * If this is discard request, set bi_vcnt 0. We don't
 924                          * want to confuse SCSI because SCSI will replace payload
 925                          */
 926                         if (rw & REQ_DISCARD)
 927                                 rbi->bi_vcnt = 0;
 928                         if (conf->mddev->gendisk)
 929                                 trace_block_bio_remap(bdev_get_queue(rbi->bi_bdev),
 930                                                       rbi, disk_devt(conf->mddev->gendisk),
 931                                                       sh->dev[i].sector);
 932                         generic_make_request(rbi);
 933                 }
 934                 if (!rdev && !rrdev) {
 935                         if (rw & WRITE)
 936                                 set_bit(STRIPE_DEGRADED, &sh->state);
 937                         pr_debug("skip op %ld on disc %d for sector %llu\n",
 938                                 bi->bi_rw, i, (unsigned long long)sh->sector);
 939                         clear_bit(R5_LOCKED, &sh->dev[i].flags);
 940                         set_bit(STRIPE_HANDLE, &sh->state);
 941                 }
 942         }
 943 }
 944
 945 static struct dma_async_tx_descriptor *
 946 async_copy_data(int frombio, struct bio *bio, struct page **page,
 947         sector_t sector, struct dma_async_tx_descriptor *tx,
 948         struct stripe_head *sh)
 949 {
 950         struct bio_vec bvl;
 951         struct bvec_iter iter;
 952         struct page *bio_page;
 953         int page_offset;
 954         struct async_submit_ctl submit;
 955         enum async_tx_flags flags = 0;
 956
 957         if (bio->bi_iter.bi_sector >= sector)
 958                 page_offset = (signed)(bio->bi_iter.bi_sector - sector) * 512;
 959         else
 960                 page_offset = (signed)(sector - bio->bi_iter.bi_sector) * -512;
 961
 962         if (frombio)
 963                 flags |= ASYNC_TX_FENCE;
 964         init_async_submit(&submit, flags, tx, NULL, NULL, NULL);
 965
 966         bio_for_each_segment(bvl, bio, iter) {
 967                 int len = bvl.bv_len;
 968                 int clen;
 969                 int b_offset = 0;
 970
 971                 if (page_offset < 0) {
 972                         b_offset = -page_offset;
 973                         page_offset += b_offset;
 974                         len -= b_offset;
 975                 }
 976
 977                 if (len > 0 && page_offset + len > STRIPE_SIZE)
 978                         clen = STRIPE_SIZE - page_offset;
 979                 else
 980                         clen = len;
 981
 982                 if (clen > 0) {
 983                         b_offset += bvl.bv_offset;
 984                         bio_page = bvl.bv_page;
 985                         if (frombio) {
 986                                 if (sh->raid_conf->skip_copy &&
 987                                     b_offset == 0 && page_offset == 0 &&
 988                                     clen == STRIPE_SIZE)
 989                                         *page = bio_page;
 990                                 else
 991                                         tx = async_memcpy(*page, bio_page, page_offset,
 992                                                   b_offset, clen, &submit);
 993                         } else
 994                                 tx = async_memcpy(bio_page, *page, b_offset,
 995                                                   page_offset, clen, &submit);
 996                 }
 997                 /* chain the operations */
 998                 submit.depend_tx = tx;
 999
1000                 if (clen < len) /* hit end of page */
1001                         break;
1002                 page_offset +=  len;
1003         }
1004
1005         return tx;
1006 }
1007
1008 static void ops_complete_biofill(void *stripe_head_ref)
1009 {
1010         struct stripe_head *sh = stripe_head_ref;
1011         struct bio *return_bi = NULL;
1012         int i;
1013
1014         pr_debug("%s: stripe %llu\n", __func__,
1015                 (unsigned long long)sh->sector);
1016
1017         /* clear completed biofills */
1018         for (i = sh->disks; i--; ) {
1019                 struct r5dev *dev = &sh->dev[i];
1020
1021                 /* acknowledge completion of a biofill operation */
1022                 /* and check if we need to reply to a read request,
1023                  * new R5_Wantfill requests are held off until
1024                  * !STRIPE_BIOFILL_RUN
1025                  */
1026                 if (test_and_clear_bit(R5_Wantfill, &dev->flags)) {
1027                         struct bio *rbi, *rbi2;
1028
1029                         BUG_ON(!dev->read);
1030                         rbi = dev->read;
1031                         dev->read = NULL;
1032                         while (rbi && rbi->bi_iter.bi_sector <
1033                                 dev->sector + STRIPE_SECTORS) {
1034                                 rbi2 = r5_next_bio(rbi, dev->sector);
1035                                 if (!raid5_dec_bi_active_stripes(rbi)) {
1036                                         rbi->bi_next = return_bi;
1037                                         return_bi = rbi;
1038                                 }
1039                                 rbi = rbi2;
1040                         }
1041                 }
1042         }
1043         clear_bit(STRIPE_BIOFILL_RUN, &sh->state);
1044
1045         return_io(return_bi);
1046
1047         set_bit(STRIPE_HANDLE, &sh->state);
1048         release_stripe(sh);
1049 }
1050
1051 static void ops_run_biofill(struct stripe_head *sh)
1052 {
1053         struct dma_async_tx_descriptor *tx = NULL;
1054         struct async_submit_ctl submit;
1055         int i;
1056
1057         pr_debug("%s: stripe %llu\n", __func__,
1058                 (unsigned long long)sh->sector);
1059
1060         for (i = sh->disks; i--; ) {
1061                 struct r5dev *dev = &sh->dev[i];
1062                 if (test_bit(R5_Wantfill, &dev->flags)) {
1063                         struct bio *rbi;
1064                         spin_lock_irq(&sh->stripe_lock);
1065                         dev->read = rbi = dev->toread;
1066                         dev->toread = NULL;
1067                         spin_unlock_irq(&sh->stripe_lock);
1068                         while (rbi && rbi->bi_iter.bi_sector <
1069                                 dev->sector + STRIPE_SECTORS) {
1070                                 tx = async_copy_data(0, rbi, &dev->page,
1071                                         dev->sector, tx, sh);
1072                                 rbi = r5_next_bio(rbi, dev->sector);
1073                         }
1074                 }
1075         }
1076
1077         atomic_inc(&sh->count);
1078         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_biofill, sh, NULL);
1079         async_trigger_callback(&submit);
1080 }
1081
1082 static void mark_target_uptodate(struct stripe_head *sh, int target)
1083 {
1084         struct r5dev *tgt;
1085
1086         if (target < 0)
1087                 return;
1088
1089         tgt = &sh->dev[target];
1090         set_bit(R5_UPTODATE, &tgt->flags);
1091         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1092         clear_bit(R5_Wantcompute, &tgt->flags);
1093 }
1094
1095 static void ops_complete_compute(void *stripe_head_ref)
1096 {
1097         struct stripe_head *sh = stripe_head_ref;
1098
1099         pr_debug("%s: stripe %llu\n", __func__,
1100                 (unsigned long long)sh->sector);
1101
1102         /* mark the computed target(s) as uptodate */
1103         mark_target_uptodate(sh, sh->ops.target);
1104         mark_target_uptodate(sh, sh->ops.target2);
1105
1106         clear_bit(STRIPE_COMPUTE_RUN, &sh->state);
1107         if (sh->check_state == check_state_compute_run)
1108                 sh->check_state = check_state_compute_result;
1109         set_bit(STRIPE_HANDLE, &sh->state);
1110         release_stripe(sh);
1111 }
1112
1113 /* return a pointer to the address conversion region of the scribble buffer */
1114 static addr_conv_t *to_addr_conv(struct stripe_head *sh,
1115                                  struct raid5_percpu *percpu)
1116 {
1117         return percpu->scribble + sizeof(struct page *) * (sh->disks + 2);
1118 }
1119
1120 static struct dma_async_tx_descriptor *
1121 ops_run_compute5(struct stripe_head *sh, struct raid5_percpu *percpu)
1122 {
1123         int disks = sh->disks;
1124         struct page **xor_srcs = percpu->scribble;
1125         int target = sh->ops.target;
1126         struct r5dev *tgt = &sh->dev[target];
1127         struct page *xor_dest = tgt->page;
1128         int count = 0;
1129         struct dma_async_tx_descriptor *tx;
1130         struct async_submit_ctl submit;
1131         int i;
1132
1133         pr_debug("%s: stripe %llu block: %d\n",
1134                 __func__, (unsigned long long)sh->sector, target);
1135         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1136
1137         for (i = disks; i--; )
1138                 if (i != target)
1139                         xor_srcs[count++] = sh->dev[i].page;
1140
1141         atomic_inc(&sh->count);
1142
1143         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST, NULL,
1144                           ops_complete_compute, sh, to_addr_conv(sh, percpu));
1145         if (unlikely(count == 1))
1146                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1147         else
1148                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1149
1150         return tx;
1151 }
1152
1153 /* set_syndrome_sources - populate source buffers for gen_syndrome
1154  * @srcs - (struct page *) array of size sh->disks
1155  * @sh - stripe_head to parse
1156  *
1157  * Populates srcs in proper layout order for the stripe and returns the
1158  * 'count' of sources to be used in a call to async_gen_syndrome.  The P
1159  * destination buffer is recorded in srcs[count] and the Q destination
1160  * is recorded in srcs[count+1]].
1161  */
1162 static int set_syndrome_sources(struct page **srcs, struct stripe_head *sh)
1163 {
1164         int disks = sh->disks;
1165         int syndrome_disks = sh->ddf_layout ? disks : (disks - 2);
1166         int d0_idx = raid6_d0(sh);
1167         int count;
1168         int i;
1169
1170         for (i = 0; i < disks; i++)
1171                 srcs[i] = NULL;
1172
1173         count = 0;
1174         i = d0_idx;
1175         do {
1176                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1177
1178                 srcs[slot] = sh->dev[i].page;
1179                 i = raid6_next_disk(i, disks);
1180         } while (i != d0_idx);
1181
1182         return syndrome_disks;
1183 }
1184
1185 static struct dma_async_tx_descriptor *
1186 ops_run_compute6_1(struct stripe_head *sh, struct raid5_percpu *percpu)
1187 {
1188         int disks = sh->disks;
1189         struct page **blocks = percpu->scribble;
1190         int target;
1191         int qd_idx = sh->qd_idx;
1192         struct dma_async_tx_descriptor *tx;
1193         struct async_submit_ctl submit;
1194         struct r5dev *tgt;
1195         struct page *dest;
1196         int i;
1197         int count;
1198
1199         if (sh->ops.target < 0)
1200                 target = sh->ops.target2;
1201         else if (sh->ops.target2 < 0)
1202                 target = sh->ops.target;
1203         else
1204                 /* we should only have one valid target */
1205                 BUG();
1206         BUG_ON(target < 0);
1207         pr_debug("%s: stripe %llu block: %d\n",
1208                 __func__, (unsigned long long)sh->sector, target);
1209
1210         tgt = &sh->dev[target];
1211         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1212         dest = tgt->page;
1213
1214         atomic_inc(&sh->count);
1215
1216         if (target == qd_idx) {
1217                 count = set_syndrome_sources(blocks, sh);
1218                 blocks[count] = NULL; /* regenerating p is not necessary */
1219                 BUG_ON(blocks[count+1] != dest); /* q should already be set */
1220                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1221                                   ops_complete_compute, sh,
1222                                   to_addr_conv(sh, percpu));
1223                 tx = async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE, &submit);
1224         } else {
1225                 /* Compute any data- or p-drive using XOR */
1226                 count = 0;
1227                 for (i = disks; i-- ; ) {
1228                         if (i == target || i == qd_idx)
1229                                 continue;
1230                         blocks[count++] = sh->dev[i].page;
1231                 }
1232
1233                 init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1234                                   NULL, ops_complete_compute, sh,
1235                                   to_addr_conv(sh, percpu));
1236                 tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE, &submit);
1237         }
1238
1239         return tx;
1240 }
1241
1242 static struct dma_async_tx_descriptor *
1243 ops_run_compute6_2(struct stripe_head *sh, struct raid5_percpu *percpu)
1244 {
1245         int i, count, disks = sh->disks;
1246         int syndrome_disks = sh->ddf_layout ? disks : disks-2;
1247         int d0_idx = raid6_d0(sh);
1248         int faila = -1, failb = -1;
1249         int target = sh->ops.target;
1250         int target2 = sh->ops.target2;
1251         struct r5dev *tgt = &sh->dev[target];
1252         struct r5dev *tgt2 = &sh->dev[target2];
1253         struct dma_async_tx_descriptor *tx;
1254         struct page **blocks = percpu->scribble;
1255         struct async_submit_ctl submit;
1256
1257         pr_debug("%s: stripe %llu block1: %d block2: %d\n",
1258                  __func__, (unsigned long long)sh->sector, target, target2);
1259         BUG_ON(target < 0 || target2 < 0);
1260         BUG_ON(!test_bit(R5_Wantcompute, &tgt->flags));
1261         BUG_ON(!test_bit(R5_Wantcompute, &tgt2->flags));
1262
1263         /* we need to open-code set_syndrome_sources to handle the
1264          * slot number conversion for 'faila' and 'failb'
1265          */
1266         for (i = 0; i < disks ; i++)
1267                 blocks[i] = NULL;
1268         count = 0;
1269         i = d0_idx;
1270         do {
1271                 int slot = raid6_idx_to_slot(i, sh, &count, syndrome_disks);
1272
1273                 blocks[slot] = sh->dev[i].page;
1274
1275                 if (i == target)
1276                         faila = slot;
1277                 if (i == target2)
1278                         failb = slot;
1279                 i = raid6_next_disk(i, disks);
1280         } while (i != d0_idx);
1281
1282         BUG_ON(faila == failb);
1283         if (failb < faila)
1284                 swap(faila, failb);
1285         pr_debug("%s: stripe: %llu faila: %d failb: %d\n",
1286                  __func__, (unsigned long long)sh->sector, faila, failb);
1287
1288         atomic_inc(&sh->count);
1289
1290         if (failb == syndrome_disks+1) {
1291                 /* Q disk is one of the missing disks */
1292                 if (faila == syndrome_disks) {
1293                         /* Missing P+Q, just recompute */
1294                         init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1295                                           ops_complete_compute, sh,
1296                                           to_addr_conv(sh, percpu));
1297                         return async_gen_syndrome(blocks, 0, syndrome_disks+2,
1298                                                   STRIPE_SIZE, &submit);
1299                 } else {
1300                         struct page *dest;
1301                         int data_target;
1302                         int qd_idx = sh->qd_idx;
1303
1304                         /* Missing D+Q: recompute D from P, then recompute Q */
1305                         if (target == qd_idx)
1306                                 data_target = target2;
1307                         else
1308                                 data_target = target;
1309
1310                         count = 0;
1311                         for (i = disks; i-- ; ) {
1312                                 if (i == data_target || i == qd_idx)
1313                                         continue;
1314                                 blocks[count++] = sh->dev[i].page;
1315                         }
1316                         dest = sh->dev[data_target].page;
1317                         init_async_submit(&submit,
1318                                           ASYNC_TX_FENCE|ASYNC_TX_XOR_ZERO_DST,
1319                                           NULL, NULL, NULL,
1320                                           to_addr_conv(sh, percpu));
1321                         tx = async_xor(dest, blocks, 0, count, STRIPE_SIZE,
1322                                        &submit);
1323
1324                         count = set_syndrome_sources(blocks, sh);
1325                         init_async_submit(&submit, ASYNC_TX_FENCE, tx,
1326                                           ops_complete_compute, sh,
1327                                           to_addr_conv(sh, percpu));
1328                         return async_gen_syndrome(blocks, 0, count+2,
1329                                                   STRIPE_SIZE, &submit);
1330                 }
1331         } else {
1332                 init_async_submit(&submit, ASYNC_TX_FENCE, NULL,
1333                                   ops_complete_compute, sh,
1334                                   to_addr_conv(sh, percpu));
1335                 if (failb == syndrome_disks) {
1336                         /* We're missing D+P. */
1337                         return async_raid6_datap_recov(syndrome_disks+2,
1338                                                        STRIPE_SIZE, faila,
1339                                                        blocks, &submit);
1340                 } else {
1341                         /* We're missing D+D. */
1342                         return async_raid6_2data_recov(syndrome_disks+2,
1343                                                        STRIPE_SIZE, faila, failb,
1344                                                        blocks, &submit);
1345                 }
1346         }
1347 }
1348
1349 static void ops_complete_prexor(void *stripe_head_ref)
1350 {
1351         struct stripe_head *sh = stripe_head_ref;
1352
1353         pr_debug("%s: stripe %llu\n", __func__,
1354                 (unsigned long long)sh->sector);
1355 }
1356
1357 static struct dma_async_tx_descriptor *
1358 ops_run_prexor(struct stripe_head *sh, struct raid5_percpu *percpu,
1359                struct dma_async_tx_descriptor *tx)
1360 {
1361         int disks = sh->disks;
1362         struct page **xor_srcs = percpu->scribble;
1363         int count = 0, pd_idx = sh->pd_idx, i;
1364         struct async_submit_ctl submit;
1365
1366         /* existing parity data subtracted */
1367         struct page *xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1368
1369         pr_debug("%s: stripe %llu\n", __func__,
1370                 (unsigned long long)sh->sector);
1371
1372         for (i = disks; i--; ) {
1373                 struct r5dev *dev = &sh->dev[i];
1374                 /* Only process blocks that are known to be uptodate */
1375                 if (test_bit(R5_Wantdrain, &dev->flags))
1376                         xor_srcs[count++] = dev->page;
1377         }
1378
1379         init_async_submit(&submit, ASYNC_TX_FENCE|ASYNC_TX_XOR_DROP_DST, tx,
1380                           ops_complete_prexor, sh, to_addr_conv(sh, percpu));
1381         tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1382
1383         return tx;
1384 }
1385
1386 static struct dma_async_tx_descriptor *
1387 ops_run_biodrain(struct stripe_head *sh, struct dma_async_tx_descriptor *tx)
1388 {
1389         int disks = sh->disks;
1390         int i;
1391
1392         pr_debug("%s: stripe %llu\n", __func__,
1393                 (unsigned long long)sh->sector);
1394
1395         for (i = disks; i--; ) {
1396                 struct r5dev *dev = &sh->dev[i];
1397                 struct bio *chosen;
1398
1399                 if (test_and_clear_bit(R5_Wantdrain, &dev->flags)) {
1400                         struct bio *wbi;
1401
1402                         spin_lock_irq(&sh->stripe_lock);
1403                         chosen = dev->towrite;
1404                         dev->towrite = NULL;
1405                         BUG_ON(dev->written);
1406                         wbi = dev->written = chosen;
1407                         spin_unlock_irq(&sh->stripe_lock);
1408                         WARN_ON(dev->page != dev->orig_page);
1409
1410                         while (wbi && wbi->bi_iter.bi_sector <
1411                                 dev->sector + STRIPE_SECTORS) {
1412                                 if (wbi->bi_rw & REQ_FUA)
1413                                         set_bit(R5_WantFUA, &dev->flags);
1414                                 if (wbi->bi_rw & REQ_SYNC)
1415                                         set_bit(R5_SyncIO, &dev->flags);
1416                                 if (wbi->bi_rw & REQ_DISCARD)
1417                                         set_bit(R5_Discard, &dev->flags);
1418                                 else {
1419                                         tx = async_copy_data(1, wbi, &dev->page,
1420                                                 dev->sector, tx, sh);
1421                                         if (dev->page != dev->orig_page) {
1422                                                 set_bit(R5_SkipCopy, &dev->flags);
1423                                                 clear_bit(R5_UPTODATE, &dev->flags);
1424                                                 clear_bit(R5_OVERWRITE, &dev->flags);
1425                                         }
1426                                 }
1427                                 wbi = r5_next_bio(wbi, dev->sector);
1428                         }
1429                 }
1430         }
1431
1432         return tx;
1433 }
1434
1435 static void ops_complete_reconstruct(void *stripe_head_ref)
1436 {
1437         struct stripe_head *sh = stripe_head_ref;
1438         int disks = sh->disks;
1439         int pd_idx = sh->pd_idx;
1440         int qd_idx = sh->qd_idx;
1441         int i;
1442         bool fua = false, sync = false, discard = false;
1443
1444         pr_debug("%s: stripe %llu\n", __func__,
1445                 (unsigned long long)sh->sector);
1446
1447         for (i = disks; i--; ) {
1448                 fua |= test_bit(R5_WantFUA, &sh->dev[i].flags);
1449                 sync |= test_bit(R5_SyncIO, &sh->dev[i].flags);
1450                 discard |= test_bit(R5_Discard, &sh->dev[i].flags);
1451         }
1452
1453         for (i = disks; i--; ) {
1454                 struct r5dev *dev = &sh->dev[i];
1455
1456                 if (dev->written || i == pd_idx || i == qd_idx) {
1457                         if (!discard && !test_bit(R5_SkipCopy, &dev->flags))
1458                                 set_bit(R5_UPTODATE, &dev->flags);
1459                         if (fua)
1460                                 set_bit(R5_WantFUA, &dev->flags);
1461                         if (sync)
1462                                 set_bit(R5_SyncIO, &dev->flags);
1463                 }
1464         }
1465
1466         if (sh->reconstruct_state == reconstruct_state_drain_run)
1467                 sh->reconstruct_state = reconstruct_state_drain_result;
1468         else if (sh->reconstruct_state == reconstruct_state_prexor_drain_run)
1469                 sh->reconstruct_state = reconstruct_state_prexor_drain_result;
1470         else {
1471                 BUG_ON(sh->reconstruct_state != reconstruct_state_run);
1472                 sh->reconstruct_state = reconstruct_state_result;
1473         }
1474
1475         set_bit(STRIPE_HANDLE, &sh->state);
1476         release_stripe(sh);
1477 }
1478
1479 static void
1480 ops_run_reconstruct5(struct stripe_head *sh, struct raid5_percpu *percpu,
1481                      struct dma_async_tx_descriptor *tx)
1482 {
1483         int disks = sh->disks;
1484         struct page **xor_srcs = percpu->scribble;
1485         struct async_submit_ctl submit;
1486         int count = 0, pd_idx = sh->pd_idx, i;
1487         struct page *xor_dest;
1488         int prexor = 0;
1489         unsigned long flags;
1490
1491         pr_debug("%s: stripe %llu\n", __func__,
1492                 (unsigned long long)sh->sector);
1493
1494         for (i = 0; i < sh->disks; i++) {
1495                 if (pd_idx == i)
1496                         continue;
1497                 if (!test_bit(R5_Discard, &sh->dev[i].flags))
1498                         break;
1499         }
1500         if (i >= sh->disks) {
1501                 atomic_inc(&sh->count);
1502                 set_bit(R5_Discard, &sh->dev[pd_idx].flags);
1503                 ops_complete_reconstruct(sh);
1504                 return;
1505         }
1506         /* check if prexor is active which means only process blocks
1507          * that are part of a read-modify-write (written)
1508          */
1509         if (sh->reconstruct_state == reconstruct_state_prexor_drain_run) {
1510                 prexor = 1;
1511                 xor_dest = xor_srcs[count++] = sh->dev[pd_idx].page;
1512                 for (i = disks; i--; ) {
1513                         struct r5dev *dev = &sh->dev[i];
1514                         if (dev->written)
1515                                 xor_srcs[count++] = dev->page;
1516                 }
1517         } else {
1518                 xor_dest = sh->dev[pd_idx].page;
1519                 for (i = disks; i--; ) {
1520                         struct r5dev *dev = &sh->dev[i];
1521                         if (i != pd_idx)
1522                                 xor_srcs[count++] = dev->page;
1523                 }
1524         }
1525
1526         /* 1/ if we prexor'd then the dest is reused as a source
1527          * 2/ if we did not prexor then we are redoing the parity
1528          * set ASYNC_TX_XOR_DROP_DST and ASYNC_TX_XOR_ZERO_DST
1529          * for the synchronous xor case
1530          */
1531         flags = ASYNC_TX_ACK |
1532                 (prexor ? ASYNC_TX_XOR_DROP_DST : ASYNC_TX_XOR_ZERO_DST);
1533
1534         atomic_inc(&sh->count);
1535
1536         init_async_submit(&submit, flags, tx, ops_complete_reconstruct, sh,
1537                           to_addr_conv(sh, percpu));
1538         if (unlikely(count == 1))
1539                 tx = async_memcpy(xor_dest, xor_srcs[0], 0, 0, STRIPE_SIZE, &submit);
1540         else
1541                 tx = async_xor(xor_dest, xor_srcs, 0, count, STRIPE_SIZE, &submit);
1542 }
1543
1544 static void
1545 ops_run_reconstruct6(struct stripe_head *sh, struct raid5_percpu *percpu,
1546                      struct dma_async_tx_descriptor *tx)
1547 {
1548         struct async_submit_ctl submit;
1549         struct page **blocks = percpu->scribble;
1550         int count, i;
1551
1552         pr_debug("%s: stripe %llu\n", __func__, (unsigned long long)sh->sector);
1553
1554         for (i = 0; i < sh->disks; i++) {
1555                 if (sh->pd_idx == i || sh->qd_idx == i)
1556                         continue;
1557                 if (!test_bit(R5_Discard, &sh->dev[i].flags))
1558                         break;
1559         }
1560         if (i >= sh->disks) {
1561                 atomic_inc(&sh->count);
1562                 set_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
1563                 set_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
1564                 ops_complete_reconstruct(sh);
1565                 return;
1566         }
1567
1568         count = set_syndrome_sources(blocks, sh);
1569
1570         atomic_inc(&sh->count);
1571
1572         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_reconstruct,
1573                           sh, to_addr_conv(sh, percpu));
1574         async_gen_syndrome(blocks, 0, count+2, STRIPE_SIZE,  &submit);
1575 }
1576
1577 static void ops_complete_check(void *stripe_head_ref)
1578 {
1579         struct stripe_head *sh = stripe_head_ref;
1580
1581         pr_debug("%s: stripe %llu\n", __func__,
1582                 (unsigned long long)sh->sector);
1583
1584         sh->check_state = check_state_check_result;
1585         set_bit(STRIPE_HANDLE, &sh->state);
1586         release_stripe(sh);
1587 }
1588
1589 static void ops_run_check_p(struct stripe_head *sh, struct raid5_percpu *percpu)
1590 {
1591         int disks = sh->disks;
1592         int pd_idx = sh->pd_idx;
1593         int qd_idx = sh->qd_idx;
1594         struct page *xor_dest;
1595         struct page **xor_srcs = percpu->scribble;
1596         struct dma_async_tx_descriptor *tx;
1597         struct async_submit_ctl submit;
1598         int count;
1599         int i;
1600
1601         pr_debug("%s: stripe %llu\n", __func__,
1602                 (unsigned long long)sh->sector);
1603
1604         count = 0;
1605         xor_dest = sh->dev[pd_idx].page;
1606         xor_srcs[count++] = xor_dest;
1607         for (i = disks; i--; ) {
1608                 if (i == pd_idx || i == qd_idx)
1609                         continue;
1610                 xor_srcs[count++] = sh->dev[i].page;
1611         }
1612
1613         init_async_submit(&submit, 0, NULL, NULL, NULL,
1614                           to_addr_conv(sh, percpu));
1615         tx = async_xor_val(xor_dest, xor_srcs, 0, count, STRIPE_SIZE,
1616                            &sh->ops.zero_sum_result, &submit);
1617
1618         atomic_inc(&sh->count);
1619         init_async_submit(&submit, ASYNC_TX_ACK, tx, ops_complete_check, sh, NULL);
1620         tx = async_trigger_callback(&submit);
1621 }
1622
1623 static void ops_run_check_pq(struct stripe_head *sh, struct raid5_percpu *percpu, int checkp)
1624 {
1625         struct page **srcs = percpu->scribble;
1626         struct async_submit_ctl submit;
1627         int count;
1628
1629         pr_debug("%s: stripe %llu checkp: %d\n", __func__,
1630                 (unsigned long long)sh->sector, checkp);
1631
1632         count = set_syndrome_sources(srcs, sh);
1633         if (!checkp)
1634                 srcs[count] = NULL;
1635
1636         atomic_inc(&sh->count);
1637         init_async_submit(&submit, ASYNC_TX_ACK, NULL, ops_complete_check,
1638                           sh, to_addr_conv(sh, percpu));
1639         async_syndrome_val(srcs, 0, count+2, STRIPE_SIZE,
1640                            &sh->ops.zero_sum_result, percpu->spare_page, &submit);
1641 }
1642
1643 static void raid_run_ops(struct stripe_head *sh, unsigned long ops_request)
1644 {
1645         int overlap_clear = 0, i, disks = sh->disks;
1646         struct dma_async_tx_descriptor *tx = NULL;
1647         struct r5conf *conf = sh->raid_conf;
1648         int level = conf->level;
1649         struct raid5_percpu *percpu;
1650         unsigned long cpu;
1651
1652         cpu = get_cpu();
1653         percpu = per_cpu_ptr(conf->percpu, cpu);
1654         if (test_bit(STRIPE_OP_BIOFILL, &ops_request)) {
1655                 ops_run_biofill(sh);
1656                 overlap_clear++;
1657         }
1658
1659         if (test_bit(STRIPE_OP_COMPUTE_BLK, &ops_request)) {
1660                 if (level < 6)
1661                         tx = ops_run_compute5(sh, percpu);
1662                 else {
1663                         if (sh->ops.target2 < 0 || sh->ops.target < 0)
1664                                 tx = ops_run_compute6_1(sh, percpu);
1665                         else
1666                                 tx = ops_run_compute6_2(sh, percpu);
1667                 }
1668                 /* terminate the chain if reconstruct is not set to be run */
1669                 if (tx && !test_bit(STRIPE_OP_RECONSTRUCT, &ops_request))
1670                         async_tx_ack(tx);
1671         }
1672
1673         if (test_bit(STRIPE_OP_PREXOR, &ops_request))
1674                 tx = ops_run_prexor(sh, percpu, tx);
1675
1676         if (test_bit(STRIPE_OP_BIODRAIN, &ops_request)) {
1677                 tx = ops_run_biodrain(sh, tx);
1678                 overlap_clear++;
1679         }
1680
1681         if (test_bit(STRIPE_OP_RECONSTRUCT, &ops_request)) {
1682                 if (level < 6)
1683                         ops_run_reconstruct5(sh, percpu, tx);
1684                 else
1685                         ops_run_reconstruct6(sh, percpu, tx);
1686         }
1687
1688         if (test_bit(STRIPE_OP_CHECK, &ops_request)) {
1689                 if (sh->check_state == check_state_run)
1690                         ops_run_check_p(sh, percpu);
1691                 else if (sh->check_state == check_state_run_q)
1692                         ops_run_check_pq(sh, percpu, 0);
1693                 else if (sh->check_state == check_state_run_pq)
1694                         ops_run_check_pq(sh, percpu, 1);
1695                 else
1696                         BUG();
1697         }
1698
1699         if (overlap_clear)
1700                 for (i = disks; i--; ) {
1701                         struct r5dev *dev = &sh->dev[i];
1702                         if (test_and_clear_bit(R5_Overlap, &dev->flags))
1703                                 wake_up(&sh->raid_conf->wait_for_overlap);
1704                 }
1705         put_cpu();
1706 }
1707
1708 static int grow_one_stripe(struct r5conf *conf, int hash)
1709 {
1710         struct stripe_head *sh;
1711         sh = kmem_cache_zalloc(conf->slab_cache, GFP_KERNEL);
1712         if (!sh)
1713                 return 0;
1714
1715         sh->raid_conf = conf;
1716
1717         spin_lock_init(&sh->stripe_lock);
1718
1719         if (grow_buffers(sh)) {
1720                 shrink_buffers(sh);
1721                 kmem_cache_free(conf->slab_cache, sh);
1722                 return 0;
1723         }
1724         sh->hash_lock_index = hash;
1725         /* we just created an active stripe so... */
1726         atomic_set(&sh->count, 1);
1727         atomic_inc(&conf->active_stripes);
1728         INIT_LIST_HEAD(&sh->lru);
1729         release_stripe(sh);
1730         return 1;
1731 }
1732
1733 static int grow_stripes(struct r5conf *conf, int num)
1734 {
1735         struct kmem_cache *sc;
1736         int devs = max(conf->raid_disks, conf->previous_raid_disks);
1737         int hash;
1738
1739         if (conf->mddev->gendisk)
1740                 sprintf(conf->cache_name[0],
1741                         "raid%d-%s", conf->level, mdname(conf->mddev));
1742         else
1743                 sprintf(conf->cache_name[0],
1744                         "raid%d-%p", conf->level, conf->mddev);
1745         sprintf(conf->cache_name[1], "%s-alt", conf->cache_name[0]);
1746
1747         conf->active_name = 0;
1748         sc = kmem_cache_create(conf->cache_name[conf->active_name],
1749                                sizeof(struct stripe_head)+(devs-1)*sizeof(struct r5dev),
1750                                0, 0, NULL);
1751         if (!sc)
1752                 return 1;
1753         conf->slab_cache = sc;
1754         conf->pool_size = devs;
1755         hash = conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
1756         while (num--) {
1757                 if (!grow_one_stripe(conf, hash))
1758                         return 1;
1759                 conf->max_nr_stripes++;
1760                 hash = (hash + 1) % NR_STRIPE_HASH_LOCKS;
1761         }
1762         return 0;
1763 }
1764
1765 /**
1766  * scribble_len - return the required size of the scribble region
1767  * @num - total number of disks in the array
1768  *
1769  * The size must be enough to contain:
1770  * 1/ a struct page pointer for each device in the array +2
1771  * 2/ room to convert each entry in (1) to its corresponding dma
1772  *    (dma_map_page()) or page (page_address()) address.
1773  *
1774  * Note: the +2 is for the destination buffers of the ddf/raid6 case where we
1775  * calculate over all devices (not just the data blocks), using zeros in place
1776  * of the P and Q blocks.
1777  */
1778 static size_t scribble_len(int num)
1779 {
1780         size_t len;
1781
1782         len = sizeof(struct page *) * (num+2) + sizeof(addr_conv_t) * (num+2);
1783
1784         return len;
1785 }
1786
1787 static int resize_stripes(struct r5conf *conf, int newsize)
1788 {
1789         /* Make all the stripes able to hold 'newsize' devices.
1790          * New slots in each stripe get 'page' set to a new page.
1791          *
1792          * This happens in stages:
1793          * 1/ create a new kmem_cache and allocate the required number of
1794          *    stripe_heads.
1795          * 2/ gather all the old stripe_heads and transfer the pages across
1796          *    to the new stripe_heads.  This will have the side effect of
1797          *    freezing the array as once all stripe_heads have been collected,
1798          *    no IO will be possible.  Old stripe heads are freed once their
1799          *    pages have been transferred over, and the old kmem_cache is
1800          *    freed when all stripes are done.
1801          * 3/ reallocate conf->disks to be suitable bigger.  If this fails,
1802          *    we simple return a failre status - no need to clean anything up.
1803          * 4/ allocate new pages for the new slots in the new stripe_heads.
1804          *    If this fails, we don't bother trying the shrink the
1805          *    stripe_heads down again, we just leave them as they are.
1806          *    As each stripe_head is processed the new one is released into
1807          *    active service.
1808          *
1809          * Once step2 is started, we cannot afford to wait for a write,
1810          * so we use GFP_NOIO allocations.
1811          */
1812         struct stripe_head *osh, *nsh;
1813         LIST_HEAD(newstripes);
1814         struct disk_info *ndisks;
1815         unsigned long cpu;
1816         int err;
1817         struct kmem_cache *sc;
1818         int i;
1819         int hash, cnt;
1820
1821         if (newsize <= conf->pool_size)
1822                 return 0; /* never bother to shrink */
1823
1824         err = md_allow_write(conf->mddev);
1825         if (err)
1826                 return err;
1827
1828         /* Step 1 */
1829         sc = kmem_cache_create(conf->cache_name[1-conf->active_name],
1830                                sizeof(struct stripe_head)+(newsize-1)*sizeof(struct r5dev),
1831                                0, 0, NULL);
1832         if (!sc)
1833                 return -ENOMEM;
1834
1835         for (i = conf->max_nr_stripes; i; i--) {
1836                 nsh = kmem_cache_zalloc(sc, GFP_KERNEL);
1837                 if (!nsh)
1838                         break;
1839
1840                 nsh->raid_conf = conf;
1841                 spin_lock_init(&nsh->stripe_lock);
1842
1843                 list_add(&nsh->lru, &newstripes);
1844         }
1845         if (i) {
1846                 /* didn't get enough, give up */
1847                 while (!list_empty(&newstripes)) {
1848                         nsh = list_entry(newstripes.next, struct stripe_head, lru);
1849                         list_del(&nsh->lru);
1850                         kmem_cache_free(sc, nsh);
1851                 }
1852                 kmem_cache_destroy(sc);
1853                 return -ENOMEM;
1854         }
1855         /* Step 2 - Must use GFP_NOIO now.
1856          * OK, we have enough stripes, start collecting inactive
1857          * stripes and copying them over
1858          */
1859         hash = 0;
1860         cnt = 0;
1861         list_for_each_entry(nsh, &newstripes, lru) {
1862                 lock_device_hash_lock(conf, hash);
1863                 wait_event_cmd(conf->wait_for_stripe,
1864                                     !list_empty(conf->inactive_list + hash),
1865                                     unlock_device_hash_lock(conf, hash),
1866                                     lock_device_hash_lock(conf, hash));
1867                 osh = get_free_stripe(conf, hash);
1868                 unlock_device_hash_lock(conf, hash);
1869                 atomic_set(&nsh->count, 1);
1870                 for(i=0; i<conf->pool_size; i++) {
1871                         nsh->dev[i].page = osh->dev[i].page;
1872                         nsh->dev[i].orig_page = osh->dev[i].page;
1873                 }
1874                 for( ; i<newsize; i++)
1875                         nsh->dev[i].page = NULL;
1876                 nsh->hash_lock_index = hash;
1877                 kmem_cache_free(conf->slab_cache, osh);
1878                 cnt++;
1879                 if (cnt >= conf->max_nr_stripes / NR_STRIPE_HASH_LOCKS +
1880                     !!((conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS) > hash)) {
1881                         hash++;
1882                         cnt = 0;
1883                 }
1884         }
1885         kmem_cache_destroy(conf->slab_cache);
1886
1887         /* Step 3.
1888          * At this point, we are holding all the stripes so the array
1889          * is completely stalled, so now is a good time to resize
1890          * conf->disks and the scribble region
1891          */
1892         ndisks = kzalloc(newsize * sizeof(struct disk_info), GFP_NOIO);
1893         if (ndisks) {
1894                 for (i=0; i<conf->raid_disks; i++)
1895                         ndisks[i] = conf->disks[i];
1896                 kfree(conf->disks);
1897                 conf->disks = ndisks;
1898         } else
1899                 err = -ENOMEM;
1900
1901         get_online_cpus();
1902         conf->scribble_len = scribble_len(newsize);
1903         for_each_present_cpu(cpu) {
1904                 struct raid5_percpu *percpu;
1905                 void *scribble;
1906
1907                 percpu = per_cpu_ptr(conf->percpu, cpu);
1908                 scribble = kmalloc(conf->scribble_len, GFP_NOIO);
1909
1910                 if (scribble) {
1911                         kfree(percpu->scribble);
1912                         percpu->scribble = scribble;
1913                 } else {
1914                         err = -ENOMEM;
1915                         break;
1916                 }
1917         }
1918         put_online_cpus();
1919
1920         /* Step 4, return new stripes to service */
1921         while(!list_empty(&newstripes)) {
1922                 nsh = list_entry(newstripes.next, struct stripe_head, lru);
1923                 list_del_init(&nsh->lru);
1924
1925                 for (i=conf->raid_disks; i < newsize; i++)
1926                         if (nsh->dev[i].page == NULL) {
1927                                 struct page *p = alloc_page(GFP_NOIO);
1928                                 nsh->dev[i].page = p;
1929                                 nsh->dev[i].orig_page = p;
1930                                 if (!p)
1931                                         err = -ENOMEM;
1932                         }
1933                 release_stripe(nsh);
1934         }
1935         /* critical section pass, GFP_NOIO no longer needed */
1936
1937         conf->slab_cache = sc;
1938         conf->active_name = 1-conf->active_name;
1939         conf->pool_size = newsize;
1940         return err;
1941 }
1942
1943 static int drop_one_stripe(struct r5conf *conf, int hash)
1944 {
1945         struct stripe_head *sh;
1946
1947         spin_lock_irq(conf->hash_locks + hash);
1948         sh = get_free_stripe(conf, hash);
1949         spin_unlock_irq(conf->hash_locks + hash);
1950         if (!sh)
1951                 return 0;
1952         BUG_ON(atomic_read(&sh->count));
1953         shrink_buffers(sh);
1954         kmem_cache_free(conf->slab_cache, sh);
1955         atomic_dec(&conf->active_stripes);
1956         return 1;
1957 }
1958
1959 static void shrink_stripes(struct r5conf *conf)
1960 {
1961         int hash;
1962         for (hash = 0; hash < NR_STRIPE_HASH_LOCKS; hash++)
1963                 while (drop_one_stripe(conf, hash))
1964                         ;
1965
1966         if (conf->slab_cache)
1967                 kmem_cache_destroy(conf->slab_cache);
1968         conf->slab_cache = NULL;
1969 }
1970
1971 static void raid5_end_read_request(struct bio * bi, int error)
1972 {
1973         struct stripe_head *sh = bi->bi_private;
1974         struct r5conf *conf = sh->raid_conf;
1975         int disks = sh->disks, i;
1976         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
1977         char b[BDEVNAME_SIZE];
1978         struct md_rdev *rdev = NULL;
1979         sector_t s;
1980
1981         for (i=0 ; i<disks; i++)
1982                 if (bi == &sh->dev[i].req)
1983                         break;
1984
1985         pr_debug("end_read_request %llu/%d, count: %d, uptodate %d.\n",
1986                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
1987                 uptodate);
1988         if (i == disks) {
1989                 BUG();
1990                 return;
1991         }
1992         if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
1993                 /* If replacement finished while this request was outstanding,
1994                  * 'replacement' might be NULL already.
1995                  * In that case it moved down to 'rdev'.
1996                  * rdev is not removed until all requests are finished.
1997                  */
1998                 rdev = conf->disks[i].replacement;
1999         if (!rdev)
2000                 rdev = conf->disks[i].rdev;
2001
2002         if (use_new_offset(conf, sh))
2003                 s = sh->sector + rdev->new_data_offset;
2004         else
2005                 s = sh->sector + rdev->data_offset;
2006         if (uptodate) {
2007                 set_bit(R5_UPTODATE, &sh->dev[i].flags);
2008                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2009                         /* Note that this cannot happen on a
2010                          * replacement device.  We just fail those on
2011                          * any error
2012                          */
2013                         printk_ratelimited(
2014                                 KERN_INFO
2015                                 "md/raid:%s: read error corrected"
2016                                 " (%lu sectors at %llu on %s)\n",
2017                                 mdname(conf->mddev), STRIPE_SECTORS,
2018                                 (unsigned long long)s,
2019                                 bdevname(rdev->bdev, b));
2020                         atomic_add(STRIPE_SECTORS, &rdev->corrected_errors);
2021                         clear_bit(R5_ReadError, &sh->dev[i].flags);
2022                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
2023                 } else if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2024                         clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2025
2026                 if (atomic_read(&rdev->read_errors))
2027                         atomic_set(&rdev->read_errors, 0);
2028         } else {
2029                 const char *bdn = bdevname(rdev->bdev, b);
2030                 int retry = 0;
2031                 int set_bad = 0;
2032
2033                 clear_bit(R5_UPTODATE, &sh->dev[i].flags);
2034                 atomic_inc(&rdev->read_errors);
2035                 if (test_bit(R5_ReadRepl, &sh->dev[i].flags))
2036                         printk_ratelimited(
2037                                 KERN_WARNING
2038                                 "md/raid:%s: read error on replacement device "
2039                                 "(sector %llu on %s).\n",
2040                                 mdname(conf->mddev),
2041                                 (unsigned long long)s,
2042                                 bdn);
2043                 else if (conf->mddev->degraded >= conf->max_degraded) {
2044                         set_bad = 1;
2045                         printk_ratelimited(
2046                                 KERN_WARNING
2047                                 "md/raid:%s: read error not correctable "
2048                                 "(sector %llu on %s).\n",
2049                                 mdname(conf->mddev),
2050                                 (unsigned long long)s,
2051                                 bdn);
2052                 } else if (test_bit(R5_ReWrite, &sh->dev[i].flags)) {
2053                         /* Oh, no!!! */
2054                         set_bad = 1;
2055                         printk_ratelimited(
2056                                 KERN_WARNING
2057                                 "md/raid:%s: read error NOT corrected!! "
2058                                 "(sector %llu on %s).\n",
2059                                 mdname(conf->mddev),
2060                                 (unsigned long long)s,
2061                                 bdn);
2062                 } else if (atomic_read(&rdev->read_errors)
2063                          > conf->max_nr_stripes)
2064                         printk(KERN_WARNING
2065                                "md/raid:%s: Too many read errors, failing device %s.\n",
2066                                mdname(conf->mddev), bdn);
2067                 else
2068                         retry = 1;
2069                 if (set_bad && test_bit(In_sync, &rdev->flags)
2070                     && !test_bit(R5_ReadNoMerge, &sh->dev[i].flags))
2071                         retry = 1;
2072                 if (retry)
2073                         if (test_bit(R5_ReadNoMerge, &sh->dev[i].flags)) {
2074                                 set_bit(R5_ReadError, &sh->dev[i].flags);
2075                                 clear_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2076                         } else
2077                                 set_bit(R5_ReadNoMerge, &sh->dev[i].flags);
2078                 else {
2079                         clear_bit(R5_ReadError, &sh->dev[i].flags);
2080                         clear_bit(R5_ReWrite, &sh->dev[i].flags);
2081                         if (!(set_bad
2082                               && test_bit(In_sync, &rdev->flags)
2083                               && rdev_set_badblocks(
2084                                       rdev, sh->sector, STRIPE_SECTORS, 0)))
2085                                 md_error(conf->mddev, rdev);
2086                 }
2087         }
2088         rdev_dec_pending(rdev, conf->mddev);
2089         clear_bit(R5_LOCKED, &sh->dev[i].flags);
2090         set_bit(STRIPE_HANDLE, &sh->state);
2091         release_stripe(sh);
2092 }
2093
2094 static void raid5_end_write_request(struct bio *bi, int error)
2095 {
2096         struct stripe_head *sh = bi->bi_private;
2097         struct r5conf *conf = sh->raid_conf;
2098         int disks = sh->disks, i;
2099         struct md_rdev *uninitialized_var(rdev);
2100         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
2101         sector_t first_bad;
2102         int bad_sectors;
2103         int replacement = 0;
2104
2105         for (i = 0 ; i < disks; i++) {
2106                 if (bi == &sh->dev[i].req) {
2107                         rdev = conf->disks[i].rdev;
2108                         break;
2109                 }
2110                 if (bi == &sh->dev[i].rreq) {
2111                         rdev = conf->disks[i].replacement;
2112                         if (rdev)
2113                                 replacement = 1;
2114                         else
2115                                 /* rdev was removed and 'replacement'
2116                                  * replaced it.  rdev is not removed
2117                                  * until all requests are finished.
2118                                  */
2119                                 rdev = conf->disks[i].rdev;
2120                         break;
2121                 }
2122         }
2123         pr_debug("end_write_request %llu/%d, count %d, uptodate: %d.\n",
2124                 (unsigned long long)sh->sector, i, atomic_read(&sh->count),
2125                 uptodate);
2126         if (i == disks) {
2127                 BUG();
2128                 return;
2129         }
2130
2131         if (replacement) {
2132                 if (!uptodate)
2133                         md_error(conf->mddev, rdev);
2134                 else if (is_badblock(rdev, sh->sector,
2135                                      STRIPE_SECTORS,
2136                                      &first_bad, &bad_sectors))
2137                         set_bit(R5_MadeGoodRepl, &sh->dev[i].flags);
2138         } else {
2139                 if (!uptodate) {
2140                         set_bit(STRIPE_DEGRADED, &sh->state);
2141                         set_bit(WriteErrorSeen, &rdev->flags);
2142                         set_bit(R5_WriteError, &sh->dev[i].flags);
2143                         if (!test_and_set_bit(WantReplacement, &rdev->flags))
2144                                 set_bit(MD_RECOVERY_NEEDED,
2145                                         &rdev->mddev->recovery);
2146                 } else if (is_badblock(rdev, sh->sector,
2147                                        STRIPE_SECTORS,
2148                                        &first_bad, &bad_sectors)) {
2149                         set_bit(R5_MadeGood, &sh->dev[i].flags);
2150                         if (test_bit(R5_ReadError, &sh->dev[i].flags))
2151                                 /* That was a successful write so make
2152                                  * sure it looks like we already did
2153                                  * a re-write.
2154                                  */
2155                                 set_bit(R5_ReWrite, &sh->dev[i].flags);
2156                 }
2157         }
2158         rdev_dec_pending(rdev, conf->mddev);
2159
2160         if (!test_and_clear_bit(R5_DOUBLE_LOCKED, &sh->dev[i].flags))
2161                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
2162         set_bit(STRIPE_HANDLE, &sh->state);
2163         release_stripe(sh);
2164 }
2165
2166 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous);
2167
2168 static void raid5_build_block(struct stripe_head *sh, int i, int previous)
2169 {
2170         struct r5dev *dev = &sh->dev[i];
2171
2172         bio_init(&dev->req);
2173         dev->req.bi_io_vec = &dev->vec;
2174         dev->req.bi_max_vecs = 1;
2175         dev->req.bi_private = sh;
2176
2177         bio_init(&dev->rreq);
2178         dev->rreq.bi_io_vec = &dev->rvec;
2179         dev->rreq.bi_max_vecs = 1;
2180         dev->rreq.bi_private = sh;
2181
2182         dev->flags = 0;
2183         dev->sector = compute_blocknr(sh, i, previous);
2184 }
2185
2186 static void error(struct mddev *mddev, struct md_rdev *rdev)
2187 {
2188         char b[BDEVNAME_SIZE];
2189         struct r5conf *conf = mddev->private;
2190         unsigned long flags;
2191         pr_debug("raid456: error called\n");
2192
2193         spin_lock_irqsave(&conf->device_lock, flags);
2194         clear_bit(In_sync, &rdev->flags);
2195         mddev->degraded = calc_degraded(conf);
2196         spin_unlock_irqrestore(&conf->device_lock, flags);
2197         set_bit(MD_RECOVERY_INTR, &mddev->recovery);
2198
2199         set_bit(Blocked, &rdev->flags);
2200         set_bit(Faulty, &rdev->flags);
2201         set_bit(MD_CHANGE_DEVS, &mddev->flags);
2202         printk(KERN_ALERT
2203                "md/raid:%s: Disk failure on %s, disabling device.\n"
2204                "md/raid:%s: Operation continuing on %d devices.\n",
2205                mdname(mddev),
2206                bdevname(rdev->bdev, b),
2207                mdname(mddev),
2208                conf->raid_disks - mddev->degraded);
2209 }
2210
2211 /*
2212  * Input: a 'big' sector number,
2213  * Output: index of the data and parity disk, and the sector # in them.
2214  */
2215 static sector_t raid5_compute_sector(struct r5conf *conf, sector_t r_sector,
2216                                      int previous, int *dd_idx,
2217                                      struct stripe_head *sh)
2218 {
2219         sector_t stripe, stripe2;
2220         sector_t chunk_number;
2221         unsigned int chunk_offset;
2222         int pd_idx, qd_idx;
2223         int ddf_layout = 0;
2224         sector_t new_sector;
2225         int algorithm = previous ? conf->prev_algo
2226                                  : conf->algorithm;
2227         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2228                                          : conf->chunk_sectors;
2229         int raid_disks = previous ? conf->previous_raid_disks
2230                                   : conf->raid_disks;
2231         int data_disks = raid_disks - conf->max_degraded;
2232
2233         /* First compute the information on this sector */
2234
2235         /*
2236          * Compute the chunk number and the sector offset inside the chunk
2237          */
2238         chunk_offset = sector_div(r_sector, sectors_per_chunk);
2239         chunk_number = r_sector;
2240
2241         /*
2242          * Compute the stripe number
2243          */
2244         stripe = chunk_number;
2245         *dd_idx = sector_div(stripe, data_disks);
2246         stripe2 = stripe;
2247         /*
2248          * Select the parity disk based on the user selected algorithm.
2249          */
2250         pd_idx = qd_idx = -1;
2251         switch(conf->level) {
2252         case 4:
2253                 pd_idx = data_disks;
2254                 break;
2255         case 5:
2256                 switch (algorithm) {
2257                 case ALGORITHM_LEFT_ASYMMETRIC:
2258                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2259                         if (*dd_idx >= pd_idx)
2260                                 (*dd_idx)++;
2261                         break;
2262                 case ALGORITHM_RIGHT_ASYMMETRIC:
2263                         pd_idx = sector_div(stripe2, raid_disks);
2264                         if (*dd_idx >= pd_idx)
2265                                 (*dd_idx)++;
2266                         break;
2267                 case ALGORITHM_LEFT_SYMMETRIC:
2268                         pd_idx = data_disks - sector_div(stripe2, raid_disks);
2269                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2270                         break;
2271                 case ALGORITHM_RIGHT_SYMMETRIC:
2272                         pd_idx = sector_div(stripe2, raid_disks);
2273                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2274                         break;
2275                 case ALGORITHM_PARITY_0:
2276                         pd_idx = 0;
2277                         (*dd_idx)++;
2278                         break;
2279                 case ALGORITHM_PARITY_N:
2280                         pd_idx = data_disks;
2281                         break;
2282                 default:
2283                         BUG();
2284                 }
2285                 break;
2286         case 6:
2287
2288                 switch (algorithm) {
2289                 case ALGORITHM_LEFT_ASYMMETRIC:
2290                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2291                         qd_idx = pd_idx + 1;
2292                         if (pd_idx == raid_disks-1) {
2293                                 (*dd_idx)++;    /* Q D D D P */
2294                                 qd_idx = 0;
2295                         } else if (*dd_idx >= pd_idx)
2296                                 (*dd_idx) += 2; /* D D P Q D */
2297                         break;
2298                 case ALGORITHM_RIGHT_ASYMMETRIC:
2299                         pd_idx = sector_div(stripe2, raid_disks);
2300                         qd_idx = pd_idx + 1;
2301                         if (pd_idx == raid_disks-1) {
2302                                 (*dd_idx)++;    /* Q D D D P */
2303                                 qd_idx = 0;
2304                         } else if (*dd_idx >= pd_idx)
2305                                 (*dd_idx) += 2; /* D D P Q D */
2306                         break;
2307                 case ALGORITHM_LEFT_SYMMETRIC:
2308                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2309                         qd_idx = (pd_idx + 1) % raid_disks;
2310                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2311                         break;
2312                 case ALGORITHM_RIGHT_SYMMETRIC:
2313                         pd_idx = sector_div(stripe2, raid_disks);
2314                         qd_idx = (pd_idx + 1) % raid_disks;
2315                         *dd_idx = (pd_idx + 2 + *dd_idx) % raid_disks;
2316                         break;
2317
2318                 case ALGORITHM_PARITY_0:
2319                         pd_idx = 0;
2320                         qd_idx = 1;
2321                         (*dd_idx) += 2;
2322                         break;
2323                 case ALGORITHM_PARITY_N:
2324                         pd_idx = data_disks;
2325                         qd_idx = data_disks + 1;
2326                         break;
2327
2328                 case ALGORITHM_ROTATING_ZERO_RESTART:
2329                         /* Exactly the same as RIGHT_ASYMMETRIC, but or
2330                          * of blocks for computing Q is different.
2331                          */
2332                         pd_idx = sector_div(stripe2, raid_disks);
2333                         qd_idx = pd_idx + 1;
2334                         if (pd_idx == raid_disks-1) {
2335                                 (*dd_idx)++;    /* Q D D D P */
2336                                 qd_idx = 0;
2337                         } else if (*dd_idx >= pd_idx)
2338                                 (*dd_idx) += 2; /* D D P Q D */
2339                         ddf_layout = 1;
2340                         break;
2341
2342                 case ALGORITHM_ROTATING_N_RESTART:
2343                         /* Same a left_asymmetric, by first stripe is
2344                          * D D D P Q  rather than
2345                          * Q D D D P
2346                          */
2347                         stripe2 += 1;
2348                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2349                         qd_idx = pd_idx + 1;
2350                         if (pd_idx == raid_disks-1) {
2351                                 (*dd_idx)++;    /* Q D D D P */
2352                                 qd_idx = 0;
2353                         } else if (*dd_idx >= pd_idx)
2354                                 (*dd_idx) += 2; /* D D P Q D */
2355                         ddf_layout = 1;
2356                         break;
2357
2358                 case ALGORITHM_ROTATING_N_CONTINUE:
2359                         /* Same as left_symmetric but Q is before P */
2360                         pd_idx = raid_disks - 1 - sector_div(stripe2, raid_disks);
2361                         qd_idx = (pd_idx + raid_disks - 1) % raid_disks;
2362                         *dd_idx = (pd_idx + 1 + *dd_idx) % raid_disks;
2363                         ddf_layout = 1;
2364                         break;
2365
2366                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2367                         /* RAID5 left_asymmetric, with Q on last device */
2368                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2369                         if (*dd_idx >= pd_idx)
2370                                 (*dd_idx)++;
2371                         qd_idx = raid_disks - 1;
2372                         break;
2373
2374                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2375                         pd_idx = sector_div(stripe2, raid_disks-1);
2376                         if (*dd_idx >= pd_idx)
2377                                 (*dd_idx)++;
2378                         qd_idx = raid_disks - 1;
2379                         break;
2380
2381                 case ALGORITHM_LEFT_SYMMETRIC_6:
2382                         pd_idx = data_disks - sector_div(stripe2, raid_disks-1);
2383                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2384                         qd_idx = raid_disks - 1;
2385                         break;
2386
2387                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2388                         pd_idx = sector_div(stripe2, raid_disks-1);
2389                         *dd_idx = (pd_idx + 1 + *dd_idx) % (raid_disks-1);
2390                         qd_idx = raid_disks - 1;
2391                         break;
2392
2393                 case ALGORITHM_PARITY_0_6:
2394                         pd_idx = 0;
2395                         (*dd_idx)++;
2396                         qd_idx = raid_disks - 1;
2397                         break;
2398
2399                 default:
2400                         BUG();
2401                 }
2402                 break;
2403         }
2404
2405         if (sh) {
2406                 sh->pd_idx = pd_idx;
2407                 sh->qd_idx = qd_idx;
2408                 sh->ddf_layout = ddf_layout;
2409         }
2410         /*
2411          * Finally, compute the new sector number
2412          */
2413         new_sector = (sector_t)stripe * sectors_per_chunk + chunk_offset;
2414         return new_sector;
2415 }
2416
2417 static sector_t compute_blocknr(struct stripe_head *sh, int i, int previous)
2418 {
2419         struct r5conf *conf = sh->raid_conf;
2420         int raid_disks = sh->disks;
2421         int data_disks = raid_disks - conf->max_degraded;
2422         sector_t new_sector = sh->sector, check;
2423         int sectors_per_chunk = previous ? conf->prev_chunk_sectors
2424                                          : conf->chunk_sectors;
2425         int algorithm = previous ? conf->prev_algo
2426                                  : conf->algorithm;
2427         sector_t stripe;
2428         int chunk_offset;
2429         sector_t chunk_number;
2430         int dummy1, dd_idx = i;
2431         sector_t r_sector;
2432         struct stripe_head sh2;
2433
2434         chunk_offset = sector_div(new_sector, sectors_per_chunk);
2435         stripe = new_sector;
2436
2437         if (i == sh->pd_idx)
2438                 return 0;
2439         switch(conf->level) {
2440         case 4: break;
2441         case 5:
2442                 switch (algorithm) {
2443                 case ALGORITHM_LEFT_ASYMMETRIC:
2444                 case ALGORITHM_RIGHT_ASYMMETRIC:
2445                         if (i > sh->pd_idx)
2446                                 i--;
2447                         break;
2448                 case ALGORITHM_LEFT_SYMMETRIC:
2449                 case ALGORITHM_RIGHT_SYMMETRIC:
2450                         if (i < sh->pd_idx)
2451                                 i += raid_disks;
2452                         i -= (sh->pd_idx + 1);
2453                         break;
2454                 case ALGORITHM_PARITY_0:
2455                         i -= 1;
2456                         break;
2457                 case ALGORITHM_PARITY_N:
2458                         break;
2459                 default:
2460                         BUG();
2461                 }
2462                 break;
2463         case 6:
2464                 if (i == sh->qd_idx)
2465                         return 0; /* It is the Q disk */
2466                 switch (algorithm) {
2467                 case ALGORITHM_LEFT_ASYMMETRIC:
2468                 case ALGORITHM_RIGHT_ASYMMETRIC:
2469                 case ALGORITHM_ROTATING_ZERO_RESTART:
2470                 case ALGORITHM_ROTATING_N_RESTART:
2471                         if (sh->pd_idx == raid_disks-1)
2472                                 i--;    /* Q D D D P */
2473                         else if (i > sh->pd_idx)
2474                                 i -= 2; /* D D P Q D */
2475                         break;
2476                 case ALGORITHM_LEFT_SYMMETRIC:
2477                 case ALGORITHM_RIGHT_SYMMETRIC:
2478                         if (sh->pd_idx == raid_disks-1)
2479                                 i--; /* Q D D D P */
2480                         else {
2481                                 /* D D P Q D */
2482                                 if (i < sh->pd_idx)
2483                                         i += raid_disks;
2484                                 i -= (sh->pd_idx + 2);
2485                         }
2486                         break;
2487                 case ALGORITHM_PARITY_0:
2488                         i -= 2;
2489                         break;
2490                 case ALGORITHM_PARITY_N:
2491                         break;
2492                 case ALGORITHM_ROTATING_N_CONTINUE:
2493                         /* Like left_symmetric, but P is before Q */
2494                         if (sh->pd_idx == 0)
2495                                 i--;    /* P D D D Q */
2496                         else {
2497                                 /* D D Q P D */
2498                                 if (i < sh->pd_idx)
2499                                         i += raid_disks;
2500                                 i -= (sh->pd_idx + 1);
2501                         }
2502                         break;
2503                 case ALGORITHM_LEFT_ASYMMETRIC_6:
2504                 case ALGORITHM_RIGHT_ASYMMETRIC_6:
2505                         if (i > sh->pd_idx)
2506                                 i--;
2507                         break;
2508                 case ALGORITHM_LEFT_SYMMETRIC_6:
2509                 case ALGORITHM_RIGHT_SYMMETRIC_6:
2510                         if (i < sh->pd_idx)
2511                                 i += data_disks + 1;
2512                         i -= (sh->pd_idx + 1);
2513                         break;
2514                 case ALGORITHM_PARITY_0_6:
2515                         i -= 1;
2516                         break;
2517                 default:
2518                         BUG();
2519                 }
2520                 break;
2521         }
2522
2523         chunk_number = stripe * data_disks + i;
2524         r_sector = chunk_number * sectors_per_chunk + chunk_offset;
2525
2526         check = raid5_compute_sector(conf, r_sector,
2527                                      previous, &dummy1, &sh2);
2528         if (check != sh->sector || dummy1 != dd_idx || sh2.pd_idx != sh->pd_idx
2529                 || sh2.qd_idx != sh->qd_idx) {
2530                 printk(KERN_ERR "md/raid:%s: compute_blocknr: map not correct\n",
2531                        mdname(conf->mddev));
2532                 return 0;
2533         }
2534         return r_sector;
2535 }
2536
2537 static void
2538 schedule_reconstruction(struct stripe_head *sh, struct stripe_head_state *s,
2539                          int rcw, int expand)
2540 {
2541         int i, pd_idx = sh->pd_idx, disks = sh->disks;
2542         struct r5conf *conf = sh->raid_conf;
2543         int level = conf->level;
2544
2545         if (rcw) {
2546
2547                 for (i = disks; i--; ) {
2548                         struct r5dev *dev = &sh->dev[i];
2549
2550                         if (dev->towrite) {
2551                                 set_bit(R5_LOCKED, &dev->flags);
2552                                 set_bit(R5_Wantdrain, &dev->flags);
2553                                 if (!expand)
2554                                         clear_bit(R5_UPTODATE, &dev->flags);
2555                                 s->locked++;
2556                         }
2557                 }
2558                 /* if we are not expanding this is a proper write request, and
2559                  * there will be bios with new data to be drained into the
2560                  * stripe cache
2561                  */
2562                 if (!expand) {
2563                         if (!s->locked)
2564                                 /* False alarm, nothing to do */
2565                                 return;
2566                         sh->reconstruct_state = reconstruct_state_drain_run;
2567                         set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2568                 } else
2569                         sh->reconstruct_state = reconstruct_state_run;
2570
2571                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2572
2573                 if (s->locked + conf->max_degraded == disks)
2574                         if (!test_and_set_bit(STRIPE_FULL_WRITE, &sh->state))
2575                                 atomic_inc(&conf->pending_full_writes);
2576         } else {
2577                 BUG_ON(level == 6);
2578                 BUG_ON(!(test_bit(R5_UPTODATE, &sh->dev[pd_idx].flags) ||
2579                         test_bit(R5_Wantcompute, &sh->dev[pd_idx].flags)));
2580
2581                 for (i = disks; i--; ) {
2582                         struct r5dev *dev = &sh->dev[i];
2583                         if (i == pd_idx)
2584                                 continue;
2585
2586                         if (dev->towrite &&
2587                             (test_bit(R5_UPTODATE, &dev->flags) ||
2588                              test_bit(R5_Wantcompute, &dev->flags))) {
2589                                 set_bit(R5_Wantdrain, &dev->flags);
2590                                 set_bit(R5_LOCKED, &dev->flags);
2591                                 clear_bit(R5_UPTODATE, &dev->flags);
2592                                 s->locked++;
2593                         }
2594                 }
2595                 if (!s->locked)
2596                         /* False alarm - nothing to do */
2597                         return;
2598                 sh->reconstruct_state = reconstruct_state_prexor_drain_run;
2599                 set_bit(STRIPE_OP_PREXOR, &s->ops_request);
2600                 set_bit(STRIPE_OP_BIODRAIN, &s->ops_request);
2601                 set_bit(STRIPE_OP_RECONSTRUCT, &s->ops_request);
2602         }
2603
2604         /* keep the parity disk(s) locked while asynchronous operations
2605          * are in flight
2606          */
2607         set_bit(R5_LOCKED, &sh->dev[pd_idx].flags);
2608         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
2609         s->locked++;
2610
2611         if (level == 6) {
2612                 int qd_idx = sh->qd_idx;
2613                 struct r5dev *dev = &sh->dev[qd_idx];
2614
2615                 set_bit(R5_LOCKED, &dev->flags);
2616                 clear_bit(R5_UPTODATE, &dev->flags);
2617                 s->locked++;
2618         }
2619
2620         pr_debug("%s: stripe %llu locked: %d ops_request: %lx\n",
2621                 __func__, (unsigned long long)sh->sector,
2622                 s->locked, s->ops_request);
2623 }
2624
2625 /*
2626  * Each stripe/dev can have one or more bion attached.
2627  * toread/towrite point to the first in a chain.
2628  * The bi_next chain must be in order.
2629  */
2630 static int add_stripe_bio(struct stripe_head *sh, struct bio *bi, int dd_idx, int forwrite)
2631 {
2632         struct bio **bip;
2633         struct r5conf *conf = sh->raid_conf;
2634         int firstwrite=0;
2635
2636         pr_debug("adding bi b#%llu to stripe s#%llu\n",
2637                 (unsigned long long)bi->bi_iter.bi_sector,
2638                 (unsigned long long)sh->sector);
2639
2640         /*
2641          * If several bio share a stripe. The bio bi_phys_segments acts as a
2642          * reference count to avoid race. The reference count should already be
2643          * increased before this function is called (for example, in
2644          * make_request()), so other bio sharing this stripe will not free the
2645          * stripe. If a stripe is owned by one stripe, the stripe lock will
2646          * protect it.
2647          */
2648         spin_lock_irq(&sh->stripe_lock);
2649         if (forwrite) {
2650                 bip = &sh->dev[dd_idx].towrite;
2651                 if (*bip == NULL)
2652                         firstwrite = 1;
2653         } else
2654                 bip = &sh->dev[dd_idx].toread;
2655         while (*bip && (*bip)->bi_iter.bi_sector < bi->bi_iter.bi_sector) {
2656                 if (bio_end_sector(*bip) > bi->bi_iter.bi_sector)
2657                         goto overlap;
2658                 bip = & (*bip)->bi_next;
2659         }
2660         if (*bip && (*bip)->bi_iter.bi_sector < bio_end_sector(bi))
2661                 goto overlap;
2662
2663         BUG_ON(*bip && bi->bi_next && (*bip) != bi->bi_next);
2664         if (*bip)
2665                 bi->bi_next = *bip;
2666         *bip = bi;
2667         raid5_inc_bi_active_stripes(bi);
2668
2669         if (forwrite) {
2670                 /* check if page is covered */
2671                 sector_t sector = sh->dev[dd_idx].sector;
2672                 for (bi=sh->dev[dd_idx].towrite;
2673                      sector < sh->dev[dd_idx].sector + STRIPE_SECTORS &&
2674                              bi && bi->bi_iter.bi_sector <= sector;
2675                      bi = r5_next_bio(bi, sh->dev[dd_idx].sector)) {
2676                         if (bio_end_sector(bi) >= sector)
2677                                 sector = bio_end_sector(bi);
2678                 }
2679                 if (sector >= sh->dev[dd_idx].sector + STRIPE_SECTORS)
2680                         set_bit(R5_OVERWRITE, &sh->dev[dd_idx].flags);
2681         }
2682
2683         pr_debug("added bi b#%llu to stripe s#%llu, disk %d.\n",
2684                 (unsigned long long)(*bip)->bi_iter.bi_sector,
2685                 (unsigned long long)sh->sector, dd_idx);
2686         spin_unlock_irq(&sh->stripe_lock);
2687
2688         if (conf->mddev->bitmap && firstwrite) {
2689                 bitmap_startwrite(conf->mddev->bitmap, sh->sector,
2690                                   STRIPE_SECTORS, 0);
2691                 sh->bm_seq = conf->seq_flush+1;
2692                 set_bit(STRIPE_BIT_DELAY, &sh->state);
2693         }
2694         return 1;
2695
2696  overlap:
2697         set_bit(R5_Overlap, &sh->dev[dd_idx].flags);
2698         spin_unlock_irq(&sh->stripe_lock);
2699         return 0;
2700 }
2701
2702 static void end_reshape(struct r5conf *conf);
2703
2704 static void stripe_set_idx(sector_t stripe, struct r5conf *conf, int previous,
2705                             struct stripe_head *sh)
2706 {
2707         int sectors_per_chunk =
2708                 previous ? conf->prev_chunk_sectors : conf->chunk_sectors;
2709         int dd_idx;
2710         int chunk_offset = sector_div(stripe, sectors_per_chunk);
2711         int disks = previous ? conf->previous_raid_disks : conf->raid_disks;
2712
2713         raid5_compute_sector(conf,
2714                              stripe * (disks - conf->max_degraded)
2715                              *sectors_per_chunk + chunk_offset,
2716                              previous,
2717                              &dd_idx, sh);
2718 }
2719
2720 static void
2721 handle_failed_stripe(struct r5conf *conf, struct stripe_head *sh,
2722                                 struct stripe_head_state *s, int disks,
2723                                 struct bio **return_bi)
2724 {
2725         int i;
2726         for (i = disks; i--; ) {
2727                 struct bio *bi;
2728                 int bitmap_end = 0;
2729
2730                 if (test_bit(R5_ReadError, &sh->dev[i].flags)) {
2731                         struct md_rdev *rdev;
2732                         rcu_read_lock();
2733                         rdev = rcu_dereference(conf->disks[i].rdev);
2734                         if (rdev && test_bit(In_sync, &rdev->flags))
2735                                 atomic_inc(&rdev->nr_pending);
2736                         else
2737                                 rdev = NULL;
2738                         rcu_read_unlock();
2739                         if (rdev) {
2740                                 if (!rdev_set_badblocks(
2741                                             rdev,
2742                                             sh->sector,
2743                                             STRIPE_SECTORS, 0))
2744                                         md_error(conf->mddev, rdev);
2745                                 rdev_dec_pending(rdev, conf->mddev);
2746                         }
2747                 }
2748                 spin_lock_irq(&sh->stripe_lock);
2749                 /* fail all writes first */
2750                 bi = sh->dev[i].towrite;
2751                 sh->dev[i].towrite = NULL;
2752                 spin_unlock_irq(&sh->stripe_lock);
2753                 if (bi)
2754                         bitmap_end = 1;
2755
2756                 if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2757                         wake_up(&conf->wait_for_overlap);
2758
2759                 while (bi && bi->bi_iter.bi_sector <
2760                         sh->dev[i].sector + STRIPE_SECTORS) {
2761                         struct bio *nextbi = r5_next_bio(bi, sh->dev[i].sector);
2762                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2763                         if (!raid5_dec_bi_active_stripes(bi)) {
2764                                 md_write_end(conf->mddev);
2765                                 bi->bi_next = *return_bi;
2766                                 *return_bi = bi;
2767                         }
2768                         bi = nextbi;
2769                 }
2770                 if (bitmap_end)
2771                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2772                                 STRIPE_SECTORS, 0, 0);
2773                 bitmap_end = 0;
2774                 /* and fail all 'written' */
2775                 bi = sh->dev[i].written;
2776                 sh->dev[i].written = NULL;
2777                 if (test_and_clear_bit(R5_SkipCopy, &sh->dev[i].flags)) {
2778                         WARN_ON(test_bit(R5_UPTODATE, &sh->dev[i].flags));
2779                         sh->dev[i].page = sh->dev[i].orig_page;
2780                 }
2781
2782                 if (bi) bitmap_end = 1;
2783                 while (bi && bi->bi_iter.bi_sector <
2784                        sh->dev[i].sector + STRIPE_SECTORS) {
2785                         struct bio *bi2 = r5_next_bio(bi, sh->dev[i].sector);
2786                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
2787                         if (!raid5_dec_bi_active_stripes(bi)) {
2788                                 md_write_end(conf->mddev);
2789                                 bi->bi_next = *return_bi;
2790                                 *return_bi = bi;
2791                         }
2792                         bi = bi2;
2793                 }
2794
2795                 /* fail any reads if this device is non-operational and
2796                  * the data has not reached the cache yet.
2797                  */
2798                 if (!test_bit(R5_Wantfill, &sh->dev[i].flags) &&
2799                     (!test_bit(R5_Insync, &sh->dev[i].flags) ||
2800                       test_bit(R5_ReadError, &sh->dev[i].flags))) {
2801                         spin_lock_irq(&sh->stripe_lock);
2802                         bi = sh->dev[i].toread;
2803                         sh->dev[i].toread = NULL;
2804                         spin_unlock_irq(&sh->stripe_lock);
2805                         if (test_and_clear_bit(R5_Overlap, &sh->dev[i].flags))
2806                                 wake_up(&conf->wait_for_overlap);
2807                         while (bi && bi->bi_iter.bi_sector <
2808                                sh->dev[i].sector + STRIPE_SECTORS) {
2809                                 struct bio *nextbi =
2810                                         r5_next_bio(bi, sh->dev[i].sector);
2811                                 clear_bit(BIO_UPTODATE, &bi->bi_flags);
2812                                 if (!raid5_dec_bi_active_stripes(bi)) {
2813                                         bi->bi_next = *return_bi;
2814                                         *return_bi = bi;
2815                                 }
2816                                 bi = nextbi;
2817                         }
2818                 }
2819                 if (bitmap_end)
2820                         bitmap_endwrite(conf->mddev->bitmap, sh->sector,
2821                                         STRIPE_SECTORS, 0, 0);
2822                 /* If we were in the middle of a write the parity block might
2823                  * still be locked - so just clear all R5_LOCKED flags
2824                  */
2825                 clear_bit(R5_LOCKED, &sh->dev[i].flags);
2826         }
2827
2828         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
2829                 if (atomic_dec_and_test(&conf->pending_full_writes))
2830                         md_wakeup_thread(conf->mddev->thread);
2831 }
2832
2833 static void
2834 handle_failed_sync(struct r5conf *conf, struct stripe_head *sh,
2835                    struct stripe_head_state *s)
2836 {
2837         int abort = 0;
2838         int i;
2839
2840         clear_bit(STRIPE_SYNCING, &sh->state);
2841         if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
2842                 wake_up(&conf->wait_for_overlap);
2843         s->syncing = 0;
2844         s->replacing = 0;
2845         /* There is nothing more to do for sync/check/repair.
2846          * Don't even need to abort as that is handled elsewhere
2847          * if needed, and not always wanted e.g. if there is a known
2848          * bad block here.
2849          * For recover/replace we need to record a bad block on all
2850          * non-sync devices, or abort the recovery
2851          */
2852         if (test_bit(MD_RECOVERY_RECOVER, &conf->mddev->recovery)) {
2853                 /* During recovery devices cannot be removed, so
2854                  * locking and refcounting of rdevs is not needed
2855                  */
2856                 for (i = 0; i < conf->raid_disks; i++) {
2857                         struct md_rdev *rdev = conf->disks[i].rdev;
2858                         if (rdev
2859                             && !test_bit(Faulty, &rdev->flags)
2860                             && !test_bit(In_sync, &rdev->flags)
2861                             && !rdev_set_badblocks(rdev, sh->sector,
2862                                                    STRIPE_SECTORS, 0))
2863                                 abort = 1;
2864                         rdev = conf->disks[i].replacement;
2865                         if (rdev
2866                             && !test_bit(Faulty, &rdev->flags)
2867                             && !test_bit(In_sync, &rdev->flags)
2868                             && !rdev_set_badblocks(rdev, sh->sector,
2869                                                    STRIPE_SECTORS, 0))
2870                                 abort = 1;
2871                 }
2872                 if (abort)
2873                         conf->recovery_disabled =
2874                                 conf->mddev->recovery_disabled;
2875         }
2876         md_done_sync(conf->mddev, STRIPE_SECTORS, !abort);
2877 }
2878
2879 static int want_replace(struct stripe_head *sh, int disk_idx)
2880 {
2881         struct md_rdev *rdev;
2882         int rv = 0;
2883         /* Doing recovery so rcu locking not required */
2884         rdev = sh->raid_conf->disks[disk_idx].replacement;
2885         if (rdev
2886             && !test_bit(Faulty, &rdev->flags)
2887             && !test_bit(In_sync, &rdev->flags)
2888             && (rdev->recovery_offset <= sh->sector
2889                 || rdev->mddev->recovery_cp <= sh->sector))
2890                 rv = 1;
2891
2892         return rv;
2893 }
2894
2895 /* fetch_block - checks the given member device to see if its data needs
2896  * to be read or computed to satisfy a request.
2897  *
2898  * Returns 1 when no more member devices need to be checked, otherwise returns
2899  * 0 to tell the loop in handle_stripe_fill to continue
2900  */
2901 static int fetch_block(struct stripe_head *sh, struct stripe_head_state *s,
2902                        int disk_idx, int disks)
2903 {
2904         struct r5dev *dev = &sh->dev[disk_idx];
2905         struct r5dev *fdev[2] = { &sh->dev[s->failed_num[0]],
2906                                   &sh->dev[s->failed_num[1]] };
2907
2908         /* is the data in this block needed, and can we get it? */
2909         if (!test_bit(R5_LOCKED, &dev->flags) &&
2910             !test_bit(R5_UPTODATE, &dev->flags) &&
2911             (dev->toread ||
2912              (dev->towrite && !test_bit(R5_OVERWRITE, &dev->flags)) ||
2913              s->syncing || s->expanding ||
2914              (s->replacing && want_replace(sh, disk_idx)) ||
2915              (s->failed >= 1 && fdev[0]->toread) ||
2916              (s->failed >= 2 && fdev[1]->toread) ||
2917              (sh->raid_conf->level <= 5 && s->failed && fdev[0]->towrite &&
2918               (!test_bit(R5_Insync, &dev->flags) || test_bit(STRIPE_PREREAD_ACTIVE, &sh->state)) &&
2919               !test_bit(R5_OVERWRITE, &fdev[0]->flags)) ||
2920              ((sh->raid_conf->level == 6 ||
2921                sh->sector >= sh->raid_conf->mddev->recovery_cp)
2922               && s->failed && s->to_write &&
2923               (s->to_write - s->non_overwrite <
2924                sh->raid_conf->raid_disks - sh->raid_conf->max_degraded) &&
2925               (!test_bit(R5_Insync, &dev->flags) || test_bit(STRIPE_PREREAD_ACTIVE, &sh->state))))) {
2926                 /* we would like to get this block, possibly by computing it,
2927                  * otherwise read it if the backing disk is insync
2928                  */
2929                 BUG_ON(test_bit(R5_Wantcompute, &dev->flags));
2930                 BUG_ON(test_bit(R5_Wantread, &dev->flags));
2931                 if ((s->uptodate == disks - 1) &&
2932                     (s->failed && (disk_idx == s->failed_num[0] ||
2933                                    disk_idx == s->failed_num[1]))) {
2934                         /* have disk failed, and we're requested to fetch it;
2935                          * do compute it
2936                          */
2937                         pr_debug("Computing stripe %llu block %d\n",
2938                                (unsigned long long)sh->sector, disk_idx);
2939                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2940                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2941                         set_bit(R5_Wantcompute, &dev->flags);
2942                         sh->ops.target = disk_idx;
2943                         sh->ops.target2 = -1; /* no 2nd target */
2944                         s->req_compute = 1;
2945                         /* Careful: from this point on 'uptodate' is in the eye
2946                          * of raid_run_ops which services 'compute' operations
2947                          * before writes. R5_Wantcompute flags a block that will
2948                          * be R5_UPTODATE by the time it is needed for a
2949                          * subsequent operation.
2950                          */
2951                         s->uptodate++;
2952                         return 1;
2953                 } else if (s->uptodate == disks-2 && s->failed >= 2) {
2954                         /* Computing 2-failure is *very* expensive; only
2955                          * do it if failed >= 2
2956                          */
2957                         int other;
2958                         for (other = disks; other--; ) {
2959                                 if (other == disk_idx)
2960                                         continue;
2961                                 if (!test_bit(R5_UPTODATE,
2962                                       &sh->dev[other].flags))
2963                                         break;
2964                         }
2965                         BUG_ON(other < 0);
2966                         pr_debug("Computing stripe %llu blocks %d,%d\n",
2967                                (unsigned long long)sh->sector,
2968                                disk_idx, other);
2969                         set_bit(STRIPE_COMPUTE_RUN, &sh->state);
2970                         set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
2971                         set_bit(R5_Wantcompute, &sh->dev[disk_idx].flags);
2972                         set_bit(R5_Wantcompute, &sh->dev[other].flags);
2973                         sh->ops.target = disk_idx;
2974                         sh->ops.target2 = other;
2975                         s->uptodate += 2;
2976                         s->req_compute = 1;
2977                         return 1;
2978                 } else if (test_bit(R5_Insync, &dev->flags)) {
2979                         set_bit(R5_LOCKED, &dev->flags);
2980                         set_bit(R5_Wantread, &dev->flags);
2981                         s->locked++;
2982                         pr_debug("Reading block %d (sync=%d)\n",
2983                                 disk_idx, s->syncing);
2984                 }
2985         }
2986
2987         return 0;
2988 }
2989
2990 /**
2991  * handle_stripe_fill - read or compute data to satisfy pending requests.
2992  */
2993 static void handle_stripe_fill(struct stripe_head *sh,
2994                                struct stripe_head_state *s,
2995                                int disks)
2996 {
2997         int i;
2998
2999         /* look for blocks to read/compute, skip this if a compute
3000          * is already in flight, or if the stripe contents are in the
3001          * midst of changing due to a write
3002          */
3003         if (!test_bit(STRIPE_COMPUTE_RUN, &sh->state) && !sh->check_state &&
3004             !sh->reconstruct_state)
3005                 for (i = disks; i--; )
3006                         if (fetch_block(sh, s, i, disks))
3007                                 break;
3008         set_bit(STRIPE_HANDLE, &sh->state);
3009 }
3010
3011 /* handle_stripe_clean_event
3012  * any written block on an uptodate or failed drive can be returned.
3013  * Note that if we 'wrote' to a failed drive, it will be UPTODATE, but
3014  * never LOCKED, so we don't need to test 'failed' directly.
3015  */
3016 static void handle_stripe_clean_event(struct r5conf *conf,
3017         struct stripe_head *sh, int disks, struct bio **return_bi)
3018 {
3019         int i;
3020         struct r5dev *dev;
3021         int discard_pending = 0;
3022
3023         for (i = disks; i--; )
3024                 if (sh->dev[i].written) {
3025                         dev = &sh->dev[i];
3026                         if (!test_bit(R5_LOCKED, &dev->flags) &&
3027                             (test_bit(R5_UPTODATE, &dev->flags) ||
3028                              test_bit(R5_Discard, &dev->flags) ||
3029                              test_bit(R5_SkipCopy, &dev->flags))) {
3030                                 /* We can return any write requests */
3031                                 struct bio *wbi, *wbi2;
3032                                 pr_debug("Return write for disc %d\n", i);
3033                                 if (test_and_clear_bit(R5_Discard, &dev->flags))
3034                                         clear_bit(R5_UPTODATE, &dev->flags);
3035                                 if (test_and_clear_bit(R5_SkipCopy, &dev->flags)) {
3036                                         WARN_ON(test_bit(R5_UPTODATE, &dev->flags));
3037                                         dev->page = dev->orig_page;
3038                                 }
3039                                 wbi = dev->written;
3040                                 dev->written = NULL;
3041                                 while (wbi && wbi->bi_iter.bi_sector <
3042                                         dev->sector + STRIPE_SECTORS) {
3043                                         wbi2 = r5_next_bio(wbi, dev->sector);
3044                                         if (!raid5_dec_bi_active_stripes(wbi)) {
3045                                                 md_write_end(conf->mddev);
3046                                                 wbi->bi_next = *return_bi;
3047                                                 *return_bi = wbi;
3048                                         }
3049                                         wbi = wbi2;
3050                                 }
3051                                 bitmap_endwrite(conf->mddev->bitmap, sh->sector,
3052                                                 STRIPE_SECTORS,
3053                                          !test_bit(STRIPE_DEGRADED, &sh->state),
3054                                                 0);
3055                         } else if (test_bit(R5_Discard, &dev->flags))
3056                                 discard_pending = 1;
3057                         WARN_ON(test_bit(R5_SkipCopy, &dev->flags));
3058                         WARN_ON(dev->page != dev->orig_page);
3059                 }
3060         if (!discard_pending &&
3061             test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags)) {
3062                 clear_bit(R5_Discard, &sh->dev[sh->pd_idx].flags);
3063                 clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3064                 if (sh->qd_idx >= 0) {
3065                         clear_bit(R5_Discard, &sh->dev[sh->qd_idx].flags);
3066                         clear_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags);
3067                 }
3068                 /* now that discard is done we can proceed with any sync */
3069                 clear_bit(STRIPE_DISCARD, &sh->state);
3070                 /*
3071                  * SCSI discard will change some bio fields and the stripe has
3072                  * no updated data, so remove it from hash list and the stripe
3073                  * will be reinitialized
3074                  */
3075                 spin_lock_irq(&conf->device_lock);
3076                 remove_hash(sh);
3077                 spin_unlock_irq(&conf->device_lock);
3078                 if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state))
3079                         set_bit(STRIPE_HANDLE, &sh->state);
3080
3081         }
3082
3083         if (test_and_clear_bit(STRIPE_FULL_WRITE, &sh->state))
3084                 if (atomic_dec_and_test(&conf->pending_full_writes))
3085                         md_wakeup_thread(conf->mddev->thread);
3086 }
3087
3088 static void handle_stripe_dirtying(struct r5conf *conf,
3089                                    struct stripe_head *sh,
3090                                    struct stripe_head_state *s,
3091                                    int disks)
3092 {
3093         int rmw = 0, rcw = 0, i;
3094         sector_t recovery_cp = conf->mddev->recovery_cp;
3095
3096         /* RAID6 requires 'rcw' in current implementation.
3097          * Otherwise, check whether resync is now happening or should start.
3098          * If yes, then the array is dirty (after unclean shutdown or
3099          * initial creation), so parity in some stripes might be inconsistent.
3100          * In this case, we need to always do reconstruct-write, to ensure
3101          * that in case of drive failure or read-error correction, we
3102          * generate correct data from the parity.
3103          */
3104         if (conf->max_degraded == 2 ||
3105             (recovery_cp < MaxSector && sh->sector >= recovery_cp)) {
3106                 /* Calculate the real rcw later - for now make it
3107                  * look like rcw is cheaper
3108                  */
3109                 rcw = 1; rmw = 2;
3110                 pr_debug("force RCW max_degraded=%u, recovery_cp=%llu sh->sector=%llu\n",
3111                          conf->max_degraded, (unsigned long long)recovery_cp,
3112                          (unsigned long long)sh->sector);
3113         } else for (i = disks; i--; ) {
3114                 /* would I have to read this buffer for read_modify_write */
3115                 struct r5dev *dev = &sh->dev[i];
3116                 if ((dev->towrite || i == sh->pd_idx) &&
3117                     !test_bit(R5_LOCKED, &dev->flags) &&
3118                     !(test_bit(R5_UPTODATE, &dev->flags) ||
3119                       test_bit(R5_Wantcompute, &dev->flags))) {
3120                         if (test_bit(R5_Insync, &dev->flags))
3121                                 rmw++;
3122                         else
3123                                 rmw += 2*disks;  /* cannot read it */
3124                 }
3125                 /* Would I have to read this buffer for reconstruct_write */
3126                 if (!test_bit(R5_OVERWRITE, &dev->flags) && i != sh->pd_idx &&
3127                     !test_bit(R5_LOCKED, &dev->flags) &&
3128                     !(test_bit(R5_UPTODATE, &dev->flags) ||
3129                     test_bit(R5_Wantcompute, &dev->flags))) {
3130                         if (test_bit(R5_Insync, &dev->flags))
3131                                 rcw++;
3132                         else
3133                                 rcw += 2*disks;
3134                 }
3135         }
3136         pr_debug("for sector %llu, rmw=%d rcw=%d\n",
3137                 (unsigned long long)sh->sector, rmw, rcw);
3138         set_bit(STRIPE_HANDLE, &sh->state);
3139         if (rmw < rcw && rmw > 0) {
3140                 /* prefer read-modify-write, but need to get some data */
3141                 if (conf->mddev->queue)
3142                         blk_add_trace_msg(conf->mddev->queue,
3143                                           "raid5 rmw %llu %d",
3144                                           (unsigned long long)sh->sector, rmw);
3145                 for (i = disks; i--; ) {
3146                         struct r5dev *dev = &sh->dev[i];
3147                         if ((dev->towrite || i == sh->pd_idx) &&
3148                             !test_bit(R5_LOCKED, &dev->flags) &&
3149                             !(test_bit(R5_UPTODATE, &dev->flags) ||
3150                             test_bit(R5_Wantcompute, &dev->flags)) &&
3151                             test_bit(R5_Insync, &dev->flags)) {
3152                                 if (test_bit(STRIPE_PREREAD_ACTIVE,
3153                                              &sh->state)) {
3154                                         pr_debug("Read_old block %d for r-m-w\n",
3155                                                  i);
3156                                         set_bit(R5_LOCKED, &dev->flags);
3157                                         set_bit(R5_Wantread, &dev->flags);
3158                                         s->locked++;
3159                                 } else {
3160                                         set_bit(STRIPE_DELAYED, &sh->state);
3161                                         set_bit(STRIPE_HANDLE, &sh->state);
3162                                 }
3163                         }
3164                 }
3165         }
3166         if (rcw <= rmw && rcw > 0) {
3167                 /* want reconstruct write, but need to get some data */
3168                 int qread =0;
3169                 rcw = 0;
3170                 for (i = disks; i--; ) {
3171                         struct r5dev *dev = &sh->dev[i];
3172                         if (!test_bit(R5_OVERWRITE, &dev->flags) &&
3173                             i != sh->pd_idx && i != sh->qd_idx &&
3174                             !test_bit(R5_LOCKED, &dev->flags) &&
3175                             !(test_bit(R5_UPTODATE, &dev->flags) ||
3176                               test_bit(R5_Wantcompute, &dev->flags))) {
3177                                 rcw++;
3178                                 if (test_bit(R5_Insync, &dev->flags) &&
3179                                     test_bit(STRIPE_PREREAD_ACTIVE,
3180                                              &sh->state)) {
3181                                         pr_debug("Read_old block "
3182                                                 "%d for Reconstruct\n", i);
3183                                         set_bit(R5_LOCKED, &dev->flags);
3184                                         set_bit(R5_Wantread, &dev->flags);
3185                                         s->locked++;
3186                                         qread++;
3187                                 } else {
3188                                         set_bit(STRIPE_DELAYED, &sh->state);
3189                                         set_bit(STRIPE_HANDLE, &sh->state);
3190                                 }
3191                         }
3192                 }
3193                 if (rcw && conf->mddev->queue)
3194                         blk_add_trace_msg(conf->mddev->queue, "raid5 rcw %llu %d %d %d",
3195                                           (unsigned long long)sh->sector,
3196                                           rcw, qread, test_bit(STRIPE_DELAYED, &sh->state));
3197         }
3198         /* now if nothing is locked, and if we have enough data,
3199          * we can start a write request
3200          */
3201         /* since handle_stripe can be called at any time we need to handle the
3202          * case where a compute block operation has been submitted and then a
3203          * subsequent call wants to start a write request.  raid_run_ops only
3204          * handles the case where compute block and reconstruct are requested
3205          * simultaneously.  If this is not the case then new writes need to be
3206          * held off until the compute completes.
3207          */
3208         if ((s->req_compute || !test_bit(STRIPE_COMPUTE_RUN, &sh->state)) &&
3209             (s->locked == 0 && (rcw == 0 || rmw == 0) &&
3210             !test_bit(STRIPE_BIT_DELAY, &sh->state)))
3211                 schedule_reconstruction(sh, s, rcw == 0, 0);
3212 }
3213
3214 static void handle_parity_checks5(struct r5conf *conf, struct stripe_head *sh,
3215                                 struct stripe_head_state *s, int disks)
3216 {
3217         struct r5dev *dev = NULL;
3218
3219         set_bit(STRIPE_HANDLE, &sh->state);
3220
3221         switch (sh->check_state) {
3222         case check_state_idle:
3223                 /* start a new check operation if there are no failures */
3224                 if (s->failed == 0) {
3225                         BUG_ON(s->uptodate != disks);
3226                         sh->check_state = check_state_run;
3227                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
3228                         clear_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags);
3229                         s->uptodate--;
3230                         break;
3231                 }
3232                 dev = &sh->dev[s->failed_num[0]];
3233                 /* fall through */
3234         case check_state_compute_result:
3235                 sh->check_state = check_state_idle;
3236                 if (!dev)
3237                         dev = &sh->dev[sh->pd_idx];
3238
3239                 /* check that a write has not made the stripe insync */
3240                 if (test_bit(STRIPE_INSYNC, &sh->state))
3241                         break;
3242
3243                 /* either failed parity check, or recovery is happening */
3244                 BUG_ON(!test_bit(R5_UPTODATE, &dev->flags));
3245                 BUG_ON(s->uptodate != disks);
3246
3247                 set_bit(R5_LOCKED, &dev->flags);
3248                 s->locked++;
3249                 set_bit(R5_Wantwrite, &dev->flags);
3250
3251                 clear_bit(STRIPE_DEGRADED, &sh->state);
3252                 set_bit(STRIPE_INSYNC, &sh->state);
3253                 break;
3254         case check_state_run:
3255                 break; /* we will be called again upon completion */
3256         case check_state_check_result:
3257                 sh->check_state = check_state_idle;
3258
3259                 /* if a failure occurred during the check operation, leave
3260                  * STRIPE_INSYNC not set and let the stripe be handled again
3261                  */
3262                 if (s->failed)
3263                         break;
3264
3265                 /* handle a successful check operation, if parity is correct
3266                  * we are done.  Otherwise update the mismatch count and repair
3267                  * parity if !MD_RECOVERY_CHECK
3268                  */
3269                 if ((sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) == 0)
3270                         /* parity is correct (on disc,
3271                          * not in buffer any more)
3272                          */
3273                         set_bit(STRIPE_INSYNC, &sh->state);
3274                 else {
3275                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3276                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3277                                 /* don't try to repair!! */
3278                                 set_bit(STRIPE_INSYNC, &sh->state);
3279                         else {
3280                                 sh->check_state = check_state_compute_run;
3281                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3282                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3283                                 set_bit(R5_Wantcompute,
3284                                         &sh->dev[sh->pd_idx].flags);
3285                                 sh->ops.target = sh->pd_idx;
3286                                 sh->ops.target2 = -1;
3287                                 s->uptodate++;
3288                         }
3289                 }
3290                 break;
3291         case check_state_compute_run:
3292                 break;
3293         default:
3294                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3295                        __func__, sh->check_state,
3296                        (unsigned long long) sh->sector);
3297                 BUG();
3298         }
3299 }
3300
3301 static void handle_parity_checks6(struct r5conf *conf, struct stripe_head *sh,
3302                                   struct stripe_head_state *s,
3303                                   int disks)
3304 {
3305         int pd_idx = sh->pd_idx;
3306         int qd_idx = sh->qd_idx;
3307         struct r5dev *dev;
3308
3309         set_bit(STRIPE_HANDLE, &sh->state);
3310
3311         BUG_ON(s->failed > 2);
3312
3313         /* Want to check and possibly repair P and Q.
3314          * However there could be one 'failed' device, in which
3315          * case we can only check one of them, possibly using the
3316          * other to generate missing data
3317          */
3318
3319         switch (sh->check_state) {
3320         case check_state_idle:
3321                 /* start a new check operation if there are < 2 failures */
3322                 if (s->failed == s->q_failed) {
3323                         /* The only possible failed device holds Q, so it
3324                          * makes sense to check P (If anything else were failed,
3325                          * we would have used P to recreate it).
3326                          */
3327                         sh->check_state = check_state_run;
3328                 }
3329                 if (!s->q_failed && s->failed < 2) {
3330                         /* Q is not failed, and we didn't use it to generate
3331                          * anything, so it makes sense to check it
3332                          */
3333                         if (sh->check_state == check_state_run)
3334                                 sh->check_state = check_state_run_pq;
3335                         else
3336                                 sh->check_state = check_state_run_q;
3337                 }
3338
3339                 /* discard potentially stale zero_sum_result */
3340                 sh->ops.zero_sum_result = 0;
3341
3342                 if (sh->check_state == check_state_run) {
3343                         /* async_xor_zero_sum destroys the contents of P */
3344                         clear_bit(R5_UPTODATE, &sh->dev[pd_idx].flags);
3345                         s->uptodate--;
3346                 }
3347                 if (sh->check_state >= check_state_run &&
3348                     sh->check_state <= check_state_run_pq) {
3349                         /* async_syndrome_zero_sum preserves P and Q, so
3350                          * no need to mark them !uptodate here
3351                          */
3352                         set_bit(STRIPE_OP_CHECK, &s->ops_request);
3353                         break;
3354                 }
3355
3356                 /* we have 2-disk failure */
3357                 BUG_ON(s->failed != 2);
3358                 /* fall through */
3359         case check_state_compute_result:
3360                 sh->check_state = check_state_idle;
3361
3362                 /* check that a write has not made the stripe insync */
3363                 if (test_bit(STRIPE_INSYNC, &sh->state))
3364                         break;
3365
3366                 /* now write out any block on a failed drive,
3367                  * or P or Q if they were recomputed
3368                  */
3369                 BUG_ON(s->uptodate < disks - 1); /* We don't need Q to recover */
3370                 if (s->failed == 2) {
3371                         dev = &sh->dev[s->failed_num[1]];
3372                         s->locked++;
3373                         set_bit(R5_LOCKED, &dev->flags);
3374                         set_bit(R5_Wantwrite, &dev->flags);
3375                 }
3376                 if (s->failed >= 1) {
3377                         dev = &sh->dev[s->failed_num[0]];
3378                         s->locked++;
3379                         set_bit(R5_LOCKED, &dev->flags);
3380                         set_bit(R5_Wantwrite, &dev->flags);
3381                 }
3382                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3383                         dev = &sh->dev[pd_idx];
3384                         s->locked++;
3385                         set_bit(R5_LOCKED, &dev->flags);
3386                         set_bit(R5_Wantwrite, &dev->flags);
3387                 }
3388                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3389                         dev = &sh->dev[qd_idx];
3390                         s->locked++;
3391                         set_bit(R5_LOCKED, &dev->flags);
3392                         set_bit(R5_Wantwrite, &dev->flags);
3393                 }
3394                 clear_bit(STRIPE_DEGRADED, &sh->state);
3395
3396                 set_bit(STRIPE_INSYNC, &sh->state);
3397                 break;
3398         case check_state_run:
3399         case check_state_run_q:
3400         case check_state_run_pq:
3401                 break; /* we will be called again upon completion */
3402         case check_state_check_result:
3403                 sh->check_state = check_state_idle;
3404
3405                 /* handle a successful check operation, if parity is correct
3406                  * we are done.  Otherwise update the mismatch count and repair
3407                  * parity if !MD_RECOVERY_CHECK
3408                  */
3409                 if (sh->ops.zero_sum_result == 0) {
3410                         /* both parities are correct */
3411                         if (!s->failed)
3412                                 set_bit(STRIPE_INSYNC, &sh->state);
3413                         else {
3414                                 /* in contrast to the raid5 case we can validate
3415                                  * parity, but still have a failure to write
3416                                  * back
3417                                  */
3418                                 sh->check_state = check_state_compute_result;
3419                                 /* Returning at this point means that we may go
3420                                  * off and bring p and/or q uptodate again so
3421                                  * we make sure to check zero_sum_result again
3422                                  * to verify if p or q need writeback
3423                                  */
3424                         }
3425                 } else {
3426                         atomic64_add(STRIPE_SECTORS, &conf->mddev->resync_mismatches);
3427                         if (test_bit(MD_RECOVERY_CHECK, &conf->mddev->recovery))
3428                                 /* don't try to repair!! */
3429                                 set_bit(STRIPE_INSYNC, &sh->state);
3430                         else {
3431                                 int *target = &sh->ops.target;
3432
3433                                 sh->ops.target = -1;
3434                                 sh->ops.target2 = -1;
3435                                 sh->check_state = check_state_compute_run;
3436                                 set_bit(STRIPE_COMPUTE_RUN, &sh->state);
3437                                 set_bit(STRIPE_OP_COMPUTE_BLK, &s->ops_request);
3438                                 if (sh->ops.zero_sum_result & SUM_CHECK_P_RESULT) {
3439                                         set_bit(R5_Wantcompute,
3440                                                 &sh->dev[pd_idx].flags);
3441                                         *target = pd_idx;
3442                                         target = &sh->ops.target2;
3443                                         s->uptodate++;
3444                                 }
3445                                 if (sh->ops.zero_sum_result & SUM_CHECK_Q_RESULT) {
3446                                         set_bit(R5_Wantcompute,
3447                                                 &sh->dev[qd_idx].flags);
3448                                         *target = qd_idx;
3449                                         s->uptodate++;
3450                                 }
3451                         }
3452                 }
3453                 break;
3454         case check_state_compute_run:
3455                 break;
3456         default:
3457                 printk(KERN_ERR "%s: unknown check_state: %d sector: %llu\n",
3458                        __func__, sh->check_state,
3459                        (unsigned long long) sh->sector);
3460                 BUG();
3461         }
3462 }
3463
3464 static void handle_stripe_expansion(struct r5conf *conf, struct stripe_head *sh)
3465 {
3466         int i;
3467
3468         /* We have read all the blocks in this stripe and now we need to
3469          * copy some of them into a target stripe for expand.
3470          */
3471         struct dma_async_tx_descriptor *tx = NULL;
3472         clear_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3473         for (i = 0; i < sh->disks; i++)
3474                 if (i != sh->pd_idx && i != sh->qd_idx) {
3475                         int dd_idx, j;
3476                         struct stripe_head *sh2;
3477                         struct async_submit_ctl submit;
3478
3479                         sector_t bn = compute_blocknr(sh, i, 1);
3480                         sector_t s = raid5_compute_sector(conf, bn, 0,
3481                                                           &dd_idx, NULL);
3482                         sh2 = get_active_stripe(conf, s, 0, 1, 1);
3483                         if (sh2 == NULL)
3484                                 /* so far only the early blocks of this stripe
3485                                  * have been requested.  When later blocks
3486                                  * get requested, we will try again
3487                                  */
3488                                 continue;
3489                         if (!test_bit(STRIPE_EXPANDING, &sh2->state) ||
3490                            test_bit(R5_Expanded, &sh2->dev[dd_idx].flags)) {
3491                                 /* must have already done this block */
3492                                 release_stripe(sh2);
3493                                 continue;
3494                         }
3495
3496                         /* place all the copies on one channel */
3497                         init_async_submit(&submit, 0, tx, NULL, NULL, NULL);
3498                         tx = async_memcpy(sh2->dev[dd_idx].page,
3499                                           sh->dev[i].page, 0, 0, STRIPE_SIZE,
3500                                           &submit);
3501
3502                         set_bit(R5_Expanded, &sh2->dev[dd_idx].flags);
3503                         set_bit(R5_UPTODATE, &sh2->dev[dd_idx].flags);
3504                         for (j = 0; j < conf->raid_disks; j++)
3505                                 if (j != sh2->pd_idx &&
3506                                     j != sh2->qd_idx &&
3507                                     !test_bit(R5_Expanded, &sh2->dev[j].flags))
3508                                         break;
3509                         if (j == conf->raid_disks) {
3510                                 set_bit(STRIPE_EXPAND_READY, &sh2->state);
3511                                 set_bit(STRIPE_HANDLE, &sh2->state);
3512                         }
3513                         release_stripe(sh2);
3514
3515                 }
3516         /* done submitting copies, wait for them to complete */
3517         async_tx_quiesce(&tx);
3518 }
3519
3520 /*
3521  * handle_stripe - do things to a stripe.
3522  *
3523  * We lock the stripe by setting STRIPE_ACTIVE and then examine the
3524  * state of various bits to see what needs to be done.
3525  * Possible results:
3526  *    return some read requests which now have data
3527  *    return some write requests which are safely on storage
3528  *    schedule a read on some buffers
3529  *    schedule a write of some buffers
3530  *    return confirmation of parity correctness
3531  *
3532  */
3533
3534 static void analyse_stripe(struct stripe_head *sh, struct stripe_head_state *s)
3535 {
3536         struct r5conf *conf = sh->raid_conf;
3537         int disks = sh->disks;
3538         struct r5dev *dev;
3539         int i;
3540         int do_recovery = 0;
3541
3542         memset(s, 0, sizeof(*s));
3543
3544         s->expanding = test_bit(STRIPE_EXPAND_SOURCE, &sh->state);
3545         s->expanded = test_bit(STRIPE_EXPAND_READY, &sh->state);
3546         s->failed_num[0] = -1;
3547         s->failed_num[1] = -1;
3548
3549         /* Now to look around and see what can be done */
3550         rcu_read_lock();
3551         for (i=disks; i--; ) {
3552                 struct md_rdev *rdev;
3553                 sector_t first_bad;
3554                 int bad_sectors;
3555                 int is_bad = 0;
3556
3557                 dev = &sh->dev[i];
3558
3559                 pr_debug("check %d: state 0x%lx read %p write %p written %p\n",
3560                          i, dev->flags,
3561                          dev->toread, dev->towrite, dev->written);
3562                 /* maybe we can reply to a read
3563                  *
3564                  * new wantfill requests are only permitted while
3565                  * ops_complete_biofill is guaranteed to be inactive
3566                  */
3567                 if (test_bit(R5_UPTODATE, &dev->flags) && dev->toread &&
3568                     !test_bit(STRIPE_BIOFILL_RUN, &sh->state))
3569                         set_bit(R5_Wantfill, &dev->flags);
3570
3571                 /* now count some things */
3572                 if (test_bit(R5_LOCKED, &dev->flags))
3573                         s->locked++;
3574                 if (test_bit(R5_UPTODATE, &dev->flags))
3575                         s->uptodate++;
3576                 if (test_bit(R5_Wantcompute, &dev->flags)) {
3577                         s->compute++;
3578                         BUG_ON(s->compute > 2);
3579                 }
3580
3581                 if (test_bit(R5_Wantfill, &dev->flags))
3582                         s->to_fill++;
3583                 else if (dev->toread)
3584                         s->to_read++;
3585                 if (dev->towrite) {
3586                         s->to_write++;
3587                         if (!test_bit(R5_OVERWRITE, &dev->flags))
3588                                 s->non_overwrite++;
3589                 }
3590                 if (dev->written)
3591                         s->written++;
3592                 /* Prefer to use the replacement for reads, but only
3593                  * if it is recovered enough and has no bad blocks.
3594                  */
3595                 rdev = rcu_dereference(conf->disks[i].replacement);
3596                 if (rdev && !test_bit(Faulty, &rdev->flags) &&
3597                     rdev->recovery_offset >= sh->sector + STRIPE_SECTORS &&
3598                     !is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3599                                  &first_bad, &bad_sectors))
3600                         set_bit(R5_ReadRepl, &dev->flags);
3601                 else {
3602                         if (rdev)
3603                                 set_bit(R5_NeedReplace, &dev->flags);
3604                         rdev = rcu_dereference(conf->disks[i].rdev);
3605                         clear_bit(R5_ReadRepl, &dev->flags);
3606                 }
3607                 if (rdev && test_bit(Faulty, &rdev->flags))
3608                         rdev = NULL;
3609                 if (rdev) {
3610                         is_bad = is_badblock(rdev, sh->sector, STRIPE_SECTORS,
3611                                              &first_bad, &bad_sectors);
3612                         if (s->blocked_rdev == NULL
3613                             && (test_bit(Blocked, &rdev->flags)
3614                                 || is_bad < 0)) {
3615                                 if (is_bad < 0)
3616                                         set_bit(BlockedBadBlocks,
3617                                                 &rdev->flags);
3618                                 s->blocked_rdev = rdev;
3619                                 atomic_inc(&rdev->nr_pending);
3620                         }
3621                 }
3622                 clear_bit(R5_Insync, &dev->flags);
3623                 if (!rdev)
3624                         /* Not in-sync */;
3625                 else if (is_bad) {
3626                         /* also not in-sync */
3627                         if (!test_bit(WriteErrorSeen, &rdev->flags) &&
3628                             test_bit(R5_UPTODATE, &dev->flags)) {
3629                                 /* treat as in-sync, but with a read error
3630                                  * which we can now try to correct
3631                                  */
3632                                 set_bit(R5_Insync, &dev->flags);
3633                                 set_bit(R5_ReadError, &dev->flags);
3634                         }
3635                 } else if (test_bit(In_sync, &rdev->flags))
3636                         set_bit(R5_Insync, &dev->flags);
3637                 else if (sh->sector + STRIPE_SECTORS <= rdev->recovery_offset)
3638                         /* in sync if before recovery_offset */
3639                         set_bit(R5_Insync, &dev->flags);
3640                 else if (test_bit(R5_UPTODATE, &dev->flags) &&
3641                          test_bit(R5_Expanded, &dev->flags))
3642                         /* If we've reshaped into here, we assume it is Insync.
3643                          * We will shortly update recovery_offset to make
3644                          * it official.
3645                          */
3646                         set_bit(R5_Insync, &dev->flags);
3647
3648                 if (test_bit(R5_WriteError, &dev->flags)) {
3649                         /* This flag does not apply to '.replacement'
3650                          * only to .rdev, so make sure to check that*/
3651                         struct md_rdev *rdev2 = rcu_dereference(
3652                                 conf->disks[i].rdev);
3653                         if (rdev2 == rdev)
3654                                 clear_bit(R5_Insync, &dev->flags);
3655                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3656                                 s->handle_bad_blocks = 1;
3657                                 atomic_inc(&rdev2->nr_pending);
3658                         } else
3659                                 clear_bit(R5_WriteError, &dev->flags);
3660                 }
3661                 if (test_bit(R5_MadeGood, &dev->flags)) {
3662                         /* This flag does not apply to '.replacement'
3663                          * only to .rdev, so make sure to check that*/
3664                         struct md_rdev *rdev2 = rcu_dereference(
3665                                 conf->disks[i].rdev);
3666                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3667                                 s->handle_bad_blocks = 1;
3668                                 atomic_inc(&rdev2->nr_pending);
3669                         } else
3670                                 clear_bit(R5_MadeGood, &dev->flags);
3671                 }
3672                 if (test_bit(R5_MadeGoodRepl, &dev->flags)) {
3673                         struct md_rdev *rdev2 = rcu_dereference(
3674                                 conf->disks[i].replacement);
3675                         if (rdev2 && !test_bit(Faulty, &rdev2->flags)) {
3676                                 s->handle_bad_blocks = 1;
3677                                 atomic_inc(&rdev2->nr_pending);
3678                         } else
3679                                 clear_bit(R5_MadeGoodRepl, &dev->flags);
3680                 }
3681                 if (!test_bit(R5_Insync, &dev->flags)) {
3682                         /* The ReadError flag will just be confusing now */
3683                         clear_bit(R5_ReadError, &dev->flags);
3684                         clear_bit(R5_ReWrite, &dev->flags);
3685                 }
3686                 if (test_bit(R5_ReadError, &dev->flags))
3687                         clear_bit(R5_Insync, &dev->flags);
3688                 if (!test_bit(R5_Insync, &dev->flags)) {
3689                         if (s->failed < 2)
3690                                 s->failed_num[s->failed] = i;
3691                         s->failed++;
3692                         if (rdev && !test_bit(Faulty, &rdev->flags))
3693                                 do_recovery = 1;
3694                 }
3695         }
3696         if (test_bit(STRIPE_SYNCING, &sh->state)) {
3697                 /* If there is a failed device being replaced,
3698                  *     we must be recovering.
3699                  * else if we are after recovery_cp, we must be syncing
3700                  * else if MD_RECOVERY_REQUESTED is set, we also are syncing.
3701                  * else we can only be replacing
3702                  * sync and recovery both need to read all devices, and so
3703                  * use the same flag.
3704                  */
3705                 if (do_recovery ||
3706                     sh->sector >= conf->mddev->recovery_cp ||
3707                     test_bit(MD_RECOVERY_REQUESTED, &(conf->mddev->recovery)))
3708                         s->syncing = 1;
3709                 else
3710                         s->replacing = 1;
3711         }
3712         rcu_read_unlock();
3713 }
3714
3715 static void handle_stripe(struct stripe_head *sh)
3716 {
3717         struct stripe_head_state s;
3718         struct r5conf *conf = sh->raid_conf;
3719         int i;
3720         int prexor;
3721         int disks = sh->disks;
3722         struct r5dev *pdev, *qdev;
3723
3724         clear_bit(STRIPE_HANDLE, &sh->state);
3725         if (test_and_set_bit_lock(STRIPE_ACTIVE, &sh->state)) {
3726                 /* already being handled, ensure it gets handled
3727                  * again when current action finishes */
3728                 set_bit(STRIPE_HANDLE, &sh->state);
3729                 return;
3730         }
3731
3732         if (test_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3733                 spin_lock(&sh->stripe_lock);
3734                 /* Cannot process 'sync' concurrently with 'discard' */
3735                 if (!test_bit(STRIPE_DISCARD, &sh->state) &&
3736                     test_and_clear_bit(STRIPE_SYNC_REQUESTED, &sh->state)) {
3737                         set_bit(STRIPE_SYNCING, &sh->state);
3738                         clear_bit(STRIPE_INSYNC, &sh->state);
3739                         clear_bit(STRIPE_REPLACED, &sh->state);
3740                 }
3741                 spin_unlock(&sh->stripe_lock);
3742         }
3743         clear_bit(STRIPE_DELAYED, &sh->state);
3744
3745         pr_debug("handling stripe %llu, state=%#lx cnt=%d, "
3746                 "pd_idx=%d, qd_idx=%d\n, check:%d, reconstruct:%d\n",
3747                (unsigned long long)sh->sector, sh->state,
3748                atomic_read(&sh->count), sh->pd_idx, sh->qd_idx,
3749                sh->check_state, sh->reconstruct_state);
3750
3751         analyse_stripe(sh, &s);
3752
3753         if (s.handle_bad_blocks) {
3754                 set_bit(STRIPE_HANDLE, &sh->state);
3755                 goto finish;
3756         }
3757
3758         if (unlikely(s.blocked_rdev)) {
3759                 if (s.syncing || s.expanding || s.expanded ||
3760                     s.replacing || s.to_write || s.written) {
3761                         set_bit(STRIPE_HANDLE, &sh->state);
3762                         goto finish;
3763                 }
3764                 /* There is nothing for the blocked_rdev to block */
3765                 rdev_dec_pending(s.blocked_rdev, conf->mddev);
3766                 s.blocked_rdev = NULL;
3767         }
3768
3769         if (s.to_fill && !test_bit(STRIPE_BIOFILL_RUN, &sh->state)) {
3770                 set_bit(STRIPE_OP_BIOFILL, &s.ops_request);
3771                 set_bit(STRIPE_BIOFILL_RUN, &sh->state);
3772         }
3773
3774         pr_debug("locked=%d uptodate=%d to_read=%d"
3775                " to_write=%d failed=%d failed_num=%d,%d\n",
3776                s.locked, s.uptodate, s.to_read, s.to_write, s.failed,
3777                s.failed_num[0], s.failed_num[1]);
3778         /* check if the array has lost more than max_degraded devices and,
3779          * if so, some requests might need to be failed.
3780          */
3781         if (s.failed > conf->max_degraded) {
3782                 sh->check_state = 0;
3783                 sh->reconstruct_state = 0;
3784                 if (s.to_read+s.to_write+s.written)
3785                         handle_failed_stripe(conf, sh, &s, disks, &s.return_bi);
3786                 if (s.syncing + s.replacing)
3787                         handle_failed_sync(conf, sh, &s);
3788         }
3789
3790         /* Now we check to see if any write operations have recently
3791          * completed
3792          */
3793         prexor = 0;
3794         if (sh->reconstruct_state == reconstruct_state_prexor_drain_result)
3795                 prexor = 1;
3796         if (sh->reconstruct_state == reconstruct_state_drain_result ||
3797             sh->reconstruct_state == reconstruct_state_prexor_drain_result) {
3798                 sh->reconstruct_state = reconstruct_state_idle;
3799
3800                 /* All the 'written' buffers and the parity block are ready to
3801                  * be written back to disk
3802                  */
3803                 BUG_ON(!test_bit(R5_UPTODATE, &sh->dev[sh->pd_idx].flags) &&
3804                        !test_bit(R5_Discard, &sh->dev[sh->pd_idx].flags));
3805                 BUG_ON(sh->qd_idx >= 0 &&
3806                        !test_bit(R5_UPTODATE, &sh->dev[sh->qd_idx].flags) &&
3807                        !test_bit(R5_Discard, &sh->dev[sh->qd_idx].flags));
3808                 for (i = disks; i--; ) {
3809                         struct r5dev *dev = &sh->dev[i];
3810                         if (test_bit(R5_LOCKED, &dev->flags) &&
3811                                 (i == sh->pd_idx || i == sh->qd_idx ||
3812                                  dev->written)) {
3813                                 pr_debug("Writing block %d\n", i);
3814                                 set_bit(R5_Wantwrite, &dev->flags);
3815                                 if (prexor)
3816                                         continue;
3817                                 if (s.failed > 1)
3818                                         continue;
3819                                 if (!test_bit(R5_Insync, &dev->flags) ||
3820                                     ((i == sh->pd_idx || i == sh->qd_idx)  &&
3821                                      s.failed == 0))
3822                                         set_bit(STRIPE_INSYNC, &sh->state);
3823                         }
3824                 }
3825                 if (test_and_clear_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
3826                         s.dec_preread_active = 1;
3827         }
3828
3829         /*
3830          * might be able to return some write requests if the parity blocks
3831          * are safe, or on a failed drive
3832          */
3833         pdev = &sh->dev[sh->pd_idx];
3834         s.p_failed = (s.failed >= 1 && s.failed_num[0] == sh->pd_idx)
3835                 || (s.failed >= 2 && s.failed_num[1] == sh->pd_idx);
3836         qdev = &sh->dev[sh->qd_idx];
3837         s.q_failed = (s.failed >= 1 && s.failed_num[0] == sh->qd_idx)
3838                 || (s.failed >= 2 && s.failed_num[1] == sh->qd_idx)
3839                 || conf->level < 6;
3840
3841         if (s.written &&
3842             (s.p_failed || ((test_bit(R5_Insync, &pdev->flags)
3843                              && !test_bit(R5_LOCKED, &pdev->flags)
3844                              && (test_bit(R5_UPTODATE, &pdev->flags) ||
3845                                  test_bit(R5_Discard, &pdev->flags))))) &&
3846             (s.q_failed || ((test_bit(R5_Insync, &qdev->flags)
3847                              && !test_bit(R5_LOCKED, &qdev->flags)
3848                              && (test_bit(R5_UPTODATE, &qdev->flags) ||
3849                                  test_bit(R5_Discard, &qdev->flags))))))
3850                 handle_stripe_clean_event(conf, sh, disks, &s.return_bi);
3851
3852         /* Now we might consider reading some blocks, either to check/generate
3853          * parity, or to satisfy requests
3854          * or to load a block that is being partially written.
3855          */
3856         if (s.to_read || s.non_overwrite
3857             || (conf->level == 6 && s.to_write && s.failed)
3858             || (s.syncing && (s.uptodate + s.compute < disks))
3859             || s.replacing
3860             || s.expanding)
3861                 handle_stripe_fill(sh, &s, disks);
3862
3863         /* Now to consider new write requests and what else, if anything
3864          * should be read.  We do not handle new writes when:
3865          * 1/ A 'write' operation (copy+xor) is already in flight.
3866          * 2/ A 'check' operation is in flight, as it may clobber the parity
3867          *    block.
3868          */
3869         if (s.to_write && !sh->reconstruct_state && !sh->check_state)
3870                 handle_stripe_dirtying(conf, sh, &s, disks);
3871
3872         /* maybe we need to check and possibly fix the parity for this stripe
3873          * Any reads will already have been scheduled, so we just see if enough
3874          * data is available.  The parity check is held off while parity
3875          * dependent operations are in flight.
3876          */
3877         if (sh->check_state ||
3878             (s.syncing && s.locked == 0 &&
3879              !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3880              !test_bit(STRIPE_INSYNC, &sh->state))) {
3881                 if (conf->level == 6)
3882                         handle_parity_checks6(conf, sh, &s, disks);
3883                 else
3884                         handle_parity_checks5(conf, sh, &s, disks);
3885         }
3886
3887         if ((s.replacing || s.syncing) && s.locked == 0
3888             && !test_bit(STRIPE_COMPUTE_RUN, &sh->state)
3889             && !test_bit(STRIPE_REPLACED, &sh->state)) {
3890                 /* Write out to replacement devices where possible */
3891                 for (i = 0; i < conf->raid_disks; i++)
3892                         if (test_bit(R5_NeedReplace, &sh->dev[i].flags)) {
3893                                 WARN_ON(!test_bit(R5_UPTODATE, &sh->dev[i].flags));
3894                                 set_bit(R5_WantReplace, &sh->dev[i].flags);
3895                                 set_bit(R5_LOCKED, &sh->dev[i].flags);
3896                                 s.locked++;
3897                         }
3898                 if (s.replacing)
3899                         set_bit(STRIPE_INSYNC, &sh->state);
3900                 set_bit(STRIPE_REPLACED, &sh->state);
3901         }
3902         if ((s.syncing || s.replacing) && s.locked == 0 &&
3903             !test_bit(STRIPE_COMPUTE_RUN, &sh->state) &&
3904             test_bit(STRIPE_INSYNC, &sh->state)) {
3905                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3906                 clear_bit(STRIPE_SYNCING, &sh->state);
3907                 if (test_and_clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags))
3908                         wake_up(&conf->wait_for_overlap);
3909         }
3910
3911         /* If the failed drives are just a ReadError, then we might need
3912          * to progress the repair/check process
3913          */
3914         if (s.failed <= conf->max_degraded && !conf->mddev->ro)
3915                 for (i = 0; i < s.failed; i++) {
3916                         struct r5dev *dev = &sh->dev[s.failed_num[i]];
3917                         if (test_bit(R5_ReadError, &dev->flags)
3918                             && !test_bit(R5_LOCKED, &dev->flags)
3919                             && test_bit(R5_UPTODATE, &dev->flags)
3920                                 ) {
3921                                 if (!test_bit(R5_ReWrite, &dev->flags)) {
3922                                         set_bit(R5_Wantwrite, &dev->flags);
3923                                         set_bit(R5_ReWrite, &dev->flags);
3924                                         set_bit(R5_LOCKED, &dev->flags);
3925                                         s.locked++;
3926                                 } else {
3927                                         /* let's read it back */
3928                                         set_bit(R5_Wantread, &dev->flags);
3929                                         set_bit(R5_LOCKED, &dev->flags);
3930                                         s.locked++;
3931                                 }
3932                         }
3933                 }
3934
3935         /* Finish reconstruct operations initiated by the expansion process */
3936         if (sh->reconstruct_state == reconstruct_state_result) {
3937                 struct stripe_head *sh_src
3938                         = get_active_stripe(conf, sh->sector, 1, 1, 1);
3939                 if (sh_src && test_bit(STRIPE_EXPAND_SOURCE, &sh_src->state)) {
3940                         /* sh cannot be written until sh_src has been read.
3941                          * so arrange for sh to be delayed a little
3942                          */
3943                         set_bit(STRIPE_DELAYED, &sh->state);
3944                         set_bit(STRIPE_HANDLE, &sh->state);
3945                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE,
3946                                               &sh_src->state))
3947                                 atomic_inc(&conf->preread_active_stripes);
3948                         release_stripe(sh_src);
3949                         goto finish;
3950                 }
3951                 if (sh_src)
3952                         release_stripe(sh_src);
3953
3954                 sh->reconstruct_state = reconstruct_state_idle;
3955                 clear_bit(STRIPE_EXPANDING, &sh->state);
3956                 for (i = conf->raid_disks; i--; ) {
3957                         set_bit(R5_Wantwrite, &sh->dev[i].flags);
3958                         set_bit(R5_LOCKED, &sh->dev[i].flags);
3959                         s.locked++;
3960                 }
3961         }
3962
3963         if (s.expanded && test_bit(STRIPE_EXPANDING, &sh->state) &&
3964             !sh->reconstruct_state) {
3965                 /* Need to write out all blocks after computing parity */
3966                 sh->disks = conf->raid_disks;
3967                 stripe_set_idx(sh->sector, conf, 0, sh);
3968                 schedule_reconstruction(sh, &s, 1, 1);
3969         } else if (s.expanded && !sh->reconstruct_state && s.locked == 0) {
3970                 clear_bit(STRIPE_EXPAND_READY, &sh->state);
3971                 atomic_dec(&conf->reshape_stripes);
3972                 wake_up(&conf->wait_for_overlap);
3973                 md_done_sync(conf->mddev, STRIPE_SECTORS, 1);
3974         }
3975
3976         if (s.expanding && s.locked == 0 &&
3977             !test_bit(STRIPE_COMPUTE_RUN, &sh->state))
3978                 handle_stripe_expansion(conf, sh);
3979
3980 finish:
3981         /* wait for this device to become unblocked */
3982         if (unlikely(s.blocked_rdev)) {
3983                 if (conf->mddev->external)
3984                         md_wait_for_blocked_rdev(s.blocked_rdev,
3985                                                  conf->mddev);
3986                 else
3987                         /* Internal metadata will immediately
3988                          * be written by raid5d, so we don't
3989                          * need to wait here.
3990                          */
3991                         rdev_dec_pending(s.blocked_rdev,
3992                                          conf->mddev);
3993         }
3994
3995         if (s.handle_bad_blocks)
3996                 for (i = disks; i--; ) {
3997                         struct md_rdev *rdev;
3998                         struct r5dev *dev = &sh->dev[i];
3999                         if (test_and_clear_bit(R5_WriteError, &dev->flags)) {
4000                                 /* We own a safe reference to the rdev */
4001                                 rdev = conf->disks[i].rdev;
4002                                 if (!rdev_set_badblocks(rdev, sh->sector,
4003                                                         STRIPE_SECTORS, 0))
4004                                         md_error(conf->mddev, rdev);
4005                                 rdev_dec_pending(rdev, conf->mddev);
4006                         }
4007                         if (test_and_clear_bit(R5_MadeGood, &dev->flags)) {
4008                                 rdev = conf->disks[i].rdev;
4009                                 rdev_clear_badblocks(rdev, sh->sector,
4010                                                      STRIPE_SECTORS, 0);
4011                                 rdev_dec_pending(rdev, conf->mddev);
4012                         }
4013                         if (test_and_clear_bit(R5_MadeGoodRepl, &dev->flags)) {
4014                                 rdev = conf->disks[i].replacement;
4015                                 if (!rdev)
4016                                         /* rdev have been moved down */
4017                                         rdev = conf->disks[i].rdev;
4018                                 rdev_clear_badblocks(rdev, sh->sector,
4019                                                      STRIPE_SECTORS, 0);
4020                                 rdev_dec_pending(rdev, conf->mddev);
4021                         }
4022                 }
4023
4024         if (s.ops_request)
4025                 raid_run_ops(sh, s.ops_request);
4026
4027         ops_run_io(sh, &s);
4028
4029         if (s.dec_preread_active) {
4030                 /* We delay this until after ops_run_io so that if make_request
4031                  * is waiting on a flush, it won't continue until the writes
4032                  * have actually been submitted.
4033                  */
4034                 atomic_dec(&conf->preread_active_stripes);
4035                 if (atomic_read(&conf->preread_active_stripes) <
4036                     IO_THRESHOLD)
4037                         md_wakeup_thread(conf->mddev->thread);
4038         }
4039
4040         return_io(s.return_bi);
4041
4042         clear_bit_unlock(STRIPE_ACTIVE, &sh->state);
4043 }
4044
4045 static void raid5_activate_delayed(struct r5conf *conf)
4046 {
4047         if (atomic_read(&conf->preread_active_stripes) < IO_THRESHOLD) {
4048                 while (!list_empty(&conf->delayed_list)) {
4049                         struct list_head *l = conf->delayed_list.next;
4050                         struct stripe_head *sh;
4051                         sh = list_entry(l, struct stripe_head, lru);
4052                         list_del_init(l);
4053                         clear_bit(STRIPE_DELAYED, &sh->state);
4054                         if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4055                                 atomic_inc(&conf->preread_active_stripes);
4056                         list_add_tail(&sh->lru, &conf->hold_list);
4057                         raid5_wakeup_stripe_thread(sh);
4058                 }
4059         }
4060 }
4061
4062 static void activate_bit_delay(struct r5conf *conf,
4063         struct list_head *temp_inactive_list)
4064 {
4065         /* device_lock is held */
4066         struct list_head head;
4067         list_add(&head, &conf->bitmap_list);
4068         list_del_init(&conf->bitmap_list);
4069         while (!list_empty(&head)) {
4070                 struct stripe_head *sh = list_entry(head.next, struct stripe_head, lru);
4071                 int hash;
4072                 list_del_init(&sh->lru);
4073                 atomic_inc(&sh->count);
4074                 hash = sh->hash_lock_index;
4075                 __release_stripe(conf, sh, &temp_inactive_list[hash]);
4076         }
4077 }
4078
4079 int md_raid5_congested(struct mddev *mddev, int bits)
4080 {
4081         struct r5conf *conf = mddev->private;
4082
4083         /* No difference between reads and writes.  Just check
4084          * how busy the stripe_cache is
4085          */
4086
4087         if (conf->inactive_blocked)
4088                 return 1;
4089         if (conf->quiesce)
4090                 return 1;
4091         if (atomic_read(&conf->empty_inactive_list_nr))
4092                 return 1;
4093
4094         return 0;
4095 }
4096 EXPORT_SYMBOL_GPL(md_raid5_congested);
4097
4098 static int raid5_congested(void *data, int bits)
4099 {
4100         struct mddev *mddev = data;
4101
4102         return mddev_congested(mddev, bits) ||
4103                 md_raid5_congested(mddev, bits);
4104 }
4105
4106 /* We want read requests to align with chunks where possible,
4107  * but write requests don't need to.
4108  */
4109 static int raid5_mergeable_bvec(struct request_queue *q,
4110                                 struct bvec_merge_data *bvm,
4111                                 struct bio_vec *biovec)
4112 {
4113         struct mddev *mddev = q->queuedata;
4114         sector_t sector = bvm->bi_sector + get_start_sect(bvm->bi_bdev);
4115         int max;
4116         unsigned int chunk_sectors = mddev->chunk_sectors;
4117         unsigned int bio_sectors = bvm->bi_size >> 9;
4118
4119         if ((bvm->bi_rw & 1) == WRITE)
4120                 return biovec->bv_len; /* always allow writes to be mergeable */
4121
4122         if (mddev->new_chunk_sectors < mddev->chunk_sectors)
4123                 chunk_sectors = mddev->new_chunk_sectors;
4124         max =  (chunk_sectors - ((sector & (chunk_sectors - 1)) + bio_sectors)) << 9;
4125         if (max < 0) max = 0;
4126         if (max <= biovec->bv_len && bio_sectors == 0)
4127                 return biovec->bv_len;
4128         else
4129                 return max;
4130 }
4131
4132 static int in_chunk_boundary(struct mddev *mddev, struct bio *bio)
4133 {
4134         sector_t sector = bio->bi_iter.bi_sector + get_start_sect(bio->bi_bdev);
4135         unsigned int chunk_sectors = mddev->chunk_sectors;
4136         unsigned int bio_sectors = bio_sectors(bio);
4137
4138         if (mddev->new_chunk_sectors < mddev->chunk_sectors)
4139                 chunk_sectors = mddev->new_chunk_sectors;
4140         return  chunk_sectors >=
4141                 ((sector & (chunk_sectors - 1)) + bio_sectors);
4142 }
4143
4144 /*
4145  *  add bio to the retry LIFO  ( in O(1) ... we are in interrupt )
4146  *  later sampled by raid5d.
4147  */
4148 static void add_bio_to_retry(struct bio *bi,struct r5conf *conf)
4149 {
4150         unsigned long flags;
4151
4152         spin_lock_irqsave(&conf->device_lock, flags);
4153
4154         bi->bi_next = conf->retry_read_aligned_list;
4155         conf->retry_read_aligned_list = bi;
4156
4157         spin_unlock_irqrestore(&conf->device_lock, flags);
4158         md_wakeup_thread(conf->mddev->thread);
4159 }
4160
4161 static struct bio *remove_bio_from_retry(struct r5conf *conf)
4162 {
4163         struct bio *bi;
4164
4165         bi = conf->retry_read_aligned;
4166         if (bi) {
4167                 conf->retry_read_aligned = NULL;
4168                 return bi;
4169         }
4170         bi = conf->retry_read_aligned_list;
4171         if(bi) {
4172                 conf->retry_read_aligned_list = bi->bi_next;
4173                 bi->bi_next = NULL;
4174                 /*
4175                  * this sets the active strip count to 1 and the processed
4176                  * strip count to zero (upper 8 bits)
4177                  */
4178                 raid5_set_bi_stripes(bi, 1); /* biased count of active stripes */
4179         }
4180
4181         return bi;
4182 }
4183
4184 /*
4185  *  The "raid5_align_endio" should check if the read succeeded and if it
4186  *  did, call bio_endio on the original bio (having bio_put the new bio
4187  *  first).
4188  *  If the read failed..
4189  */
4190 static void raid5_align_endio(struct bio *bi, int error)
4191 {
4192         struct bio* raid_bi  = bi->bi_private;
4193         struct mddev *mddev;
4194         struct r5conf *conf;
4195         int uptodate = test_bit(BIO_UPTODATE, &bi->bi_flags);
4196         struct md_rdev *rdev;
4197
4198         bio_put(bi);
4199
4200         rdev = (void*)raid_bi->bi_next;
4201         raid_bi->bi_next = NULL;
4202         mddev = rdev->mddev;
4203         conf = mddev->private;
4204
4205         rdev_dec_pending(rdev, conf->mddev);
4206
4207         if (!error && uptodate) {
4208                 trace_block_bio_complete(bdev_get_queue(raid_bi->bi_bdev),
4209                                          raid_bi, 0);
4210                 bio_endio(raid_bi, 0);
4211                 if (atomic_dec_and_test(&conf->active_aligned_reads))
4212                         wake_up(&conf->wait_for_stripe);
4213                 return;
4214         }
4215
4216         pr_debug("raid5_align_endio : io error...handing IO for a retry\n");
4217
4218         add_bio_to_retry(raid_bi, conf);
4219 }
4220
4221 static int bio_fits_rdev(struct bio *bi)
4222 {
4223         struct request_queue *q = bdev_get_queue(bi->bi_bdev);
4224
4225         if (bio_sectors(bi) > queue_max_sectors(q))
4226                 return 0;
4227         blk_recount_segments(q, bi);
4228         if (bi->bi_phys_segments > queue_max_segments(q))
4229                 return 0;
4230
4231         if (q->merge_bvec_fn)
4232                 /* it's too hard to apply the merge_bvec_fn at this stage,
4233                  * just just give up
4234                  */
4235                 return 0;
4236
4237         return 1;
4238 }
4239
4240 static int chunk_aligned_read(struct mddev *mddev, struct bio * raid_bio)
4241 {
4242         struct r5conf *conf = mddev->private;
4243         int dd_idx;
4244         struct bio* align_bi;
4245         struct md_rdev *rdev;
4246         sector_t end_sector;
4247
4248         if (!in_chunk_boundary(mddev, raid_bio)) {
4249                 pr_debug("chunk_aligned_read : non aligned\n");
4250                 return 0;
4251         }
4252         /*
4253          * use bio_clone_mddev to make a copy of the bio
4254          */
4255         align_bi = bio_clone_mddev(raid_bio, GFP_NOIO, mddev);
4256         if (!align_bi)
4257                 return 0;
4258         /*
4259          *   set bi_end_io to a new function, and set bi_private to the
4260          *     original bio.
4261          */
4262         align_bi->bi_end_io  = raid5_align_endio;
4263         align_bi->bi_private = raid_bio;
4264         /*
4265          *      compute position
4266          */
4267         align_bi->bi_iter.bi_sector =
4268                 raid5_compute_sector(conf, raid_bio->bi_iter.bi_sector,
4269                                      0, &dd_idx, NULL);
4270
4271         end_sector = bio_end_sector(align_bi);
4272         rcu_read_lock();
4273         rdev = rcu_dereference(conf->disks[dd_idx].replacement);
4274         if (!rdev || test_bit(Faulty, &rdev->flags) ||
4275             rdev->recovery_offset < end_sector) {
4276                 rdev = rcu_dereference(conf->disks[dd_idx].rdev);
4277                 if (rdev &&
4278                     (test_bit(Faulty, &rdev->flags) ||
4279                     !(test_bit(In_sync, &rdev->flags) ||
4280                       rdev->recovery_offset >= end_sector)))
4281                         rdev = NULL;
4282         }
4283         if (rdev) {
4284                 sector_t first_bad;
4285                 int bad_sectors;
4286
4287                 atomic_inc(&rdev->nr_pending);
4288                 rcu_read_unlock();
4289                 raid_bio->bi_next = (void*)rdev;
4290                 align_bi->bi_bdev =  rdev->bdev;
4291                 __clear_bit(BIO_SEG_VALID, &align_bi->bi_flags);
4292
4293                 if (!bio_fits_rdev(align_bi) ||
4294                     is_badblock(rdev, align_bi->bi_iter.bi_sector,
4295                                 bio_sectors(align_bi),
4296                                 &first_bad, &bad_sectors)) {
4297                         /* too big in some way, or has a known bad block */
4298                         bio_put(align_bi);
4299                         rdev_dec_pending(rdev, mddev);
4300                         return 0;
4301                 }
4302
4303                 /* No reshape active, so we can trust rdev->data_offset */
4304                 align_bi->bi_iter.bi_sector += rdev->data_offset;
4305
4306                 spin_lock_irq(&conf->device_lock);
4307                 wait_event_lock_irq(conf->wait_for_stripe,
4308                                     conf->quiesce == 0,
4309                                     conf->device_lock);
4310                 atomic_inc(&conf->active_aligned_reads);
4311                 spin_unlock_irq(&conf->device_lock);
4312
4313                 if (mddev->gendisk)
4314                         trace_block_bio_remap(bdev_get_queue(align_bi->bi_bdev),
4315                                               align_bi, disk_devt(mddev->gendisk),
4316                                               raid_bio->bi_iter.bi_sector);
4317                 generic_make_request(align_bi);
4318                 return 1;
4319         } else {
4320                 rcu_read_unlock();
4321                 bio_put(align_bi);
4322                 return 0;
4323         }
4324 }
4325
4326 /* __get_priority_stripe - get the next stripe to process
4327  *
4328  * Full stripe writes are allowed to pass preread active stripes up until
4329  * the bypass_threshold is exceeded.  In general the bypass_count
4330  * increments when the handle_list is handled before the hold_list; however, it
4331  * will not be incremented when STRIPE_IO_STARTED is sampled set signifying a
4332  * stripe with in flight i/o.  The bypass_count will be reset when the
4333  * head of the hold_list has changed, i.e. the head was promoted to the
4334  * handle_list.
4335  */
4336 static struct stripe_head *__get_priority_stripe(struct r5conf *conf, int group)
4337 {
4338         struct stripe_head *sh = NULL, *tmp;
4339         struct list_head *handle_list = NULL;
4340         struct r5worker_group *wg = NULL;
4341
4342         if (conf->worker_cnt_per_group == 0) {
4343                 handle_list = &conf->handle_list;
4344         } else if (group != ANY_GROUP) {
4345                 handle_list = &conf->worker_groups[group].handle_list;
4346                 wg = &conf->worker_groups[group];
4347         } else {
4348                 int i;
4349                 for (i = 0; i < conf->group_cnt; i++) {
4350                         handle_list = &conf->worker_groups[i].handle_list;
4351                         wg = &conf->worker_groups[i];
4352                         if (!list_empty(handle_list))
4353                                 break;
4354                 }
4355         }
4356
4357         pr_debug("%s: handle: %s hold: %s full_writes: %d bypass_count: %d\n",
4358                   __func__,
4359                   list_empty(handle_list) ? "empty" : "busy",
4360                   list_empty(&conf->hold_list) ? "empty" : "busy",
4361                   atomic_read(&conf->pending_full_writes), conf->bypass_count);
4362
4363         if (!list_empty(handle_list)) {
4364                 sh = list_entry(handle_list->next, typeof(*sh), lru);
4365
4366                 if (list_empty(&conf->hold_list))
4367                         conf->bypass_count = 0;
4368                 else if (!test_bit(STRIPE_IO_STARTED, &sh->state)) {
4369                         if (conf->hold_list.next == conf->last_hold)
4370                                 conf->bypass_count++;
4371                         else {
4372                                 conf->last_hold = conf->hold_list.next;
4373                                 conf->bypass_count -= conf->bypass_threshold;
4374                                 if (conf->bypass_count < 0)
4375                                         conf->bypass_count = 0;
4376                         }
4377                 }
4378         } else if (!list_empty(&conf->hold_list) &&
4379                    ((conf->bypass_threshold &&
4380                      conf->bypass_count > conf->bypass_threshold) ||
4381                     atomic_read(&conf->pending_full_writes) == 0)) {
4382
4383                 list_for_each_entry(tmp, &conf->hold_list,  lru) {
4384                         if (conf->worker_cnt_per_group == 0 ||
4385                             group == ANY_GROUP ||
4386                             !cpu_online(tmp->cpu) ||
4387                             cpu_to_group(tmp->cpu) == group) {
4388                                 sh = tmp;
4389                                 break;
4390                         }
4391                 }
4392
4393                 if (sh) {
4394                         conf->bypass_count -= conf->bypass_threshold;
4395                         if (conf->bypass_count < 0)
4396                                 conf->bypass_count = 0;
4397                 }
4398                 wg = NULL;
4399         }
4400
4401         if (!sh)
4402                 return NULL;
4403
4404         if (wg) {
4405                 wg->stripes_cnt--;
4406                 sh->group = NULL;
4407         }
4408         list_del_init(&sh->lru);
4409         BUG_ON(atomic_inc_return(&sh->count) != 1);
4410         return sh;
4411 }
4412
4413 struct raid5_plug_cb {
4414         struct blk_plug_cb      cb;
4415         struct list_head        list;
4416         struct list_head        temp_inactive_list[NR_STRIPE_HASH_LOCKS];
4417 };
4418
4419 static void raid5_unplug(struct blk_plug_cb *blk_cb, bool from_schedule)
4420 {
4421         struct raid5_plug_cb *cb = container_of(
4422                 blk_cb, struct raid5_plug_cb, cb);
4423         struct stripe_head *sh;
4424         struct mddev *mddev = cb->cb.data;
4425         struct r5conf *conf = mddev->private;
4426         int cnt = 0;
4427         int hash;
4428
4429         if (cb->list.next && !list_empty(&cb->list)) {
4430                 spin_lock_irq(&conf->device_lock);
4431                 while (!list_empty(&cb->list)) {
4432                         sh = list_first_entry(&cb->list, struct stripe_head, lru);
4433                         list_del_init(&sh->lru);
4434                         /*
4435                          * avoid race release_stripe_plug() sees
4436                          * STRIPE_ON_UNPLUG_LIST clear but the stripe
4437                          * is still in our list
4438                          */
4439                         smp_mb__before_atomic();
4440                         clear_bit(STRIPE_ON_UNPLUG_LIST, &sh->state);
4441                         /*
4442                          * STRIPE_ON_RELEASE_LIST could be set here. In that
4443                          * case, the count is always > 1 here
4444                          */
4445                         hash = sh->hash_lock_index;
4446                         __release_stripe(conf, sh, &cb->temp_inactive_list[hash]);
4447                         cnt++;
4448                 }
4449                 spin_unlock_irq(&conf->device_lock);
4450         }
4451         release_inactive_stripe_list(conf, cb->temp_inactive_list,
4452                                      NR_STRIPE_HASH_LOCKS);
4453         if (mddev->queue)
4454                 trace_block_unplug(mddev->queue, cnt, !from_schedule);
4455         kfree(cb);
4456 }
4457
4458 static void release_stripe_plug(struct mddev *mddev,
4459                                 struct stripe_head *sh)
4460 {
4461         struct blk_plug_cb *blk_cb = blk_check_plugged(
4462                 raid5_unplug, mddev,
4463                 sizeof(struct raid5_plug_cb));
4464         struct raid5_plug_cb *cb;
4465
4466         if (!blk_cb) {
4467                 release_stripe(sh);
4468                 return;
4469         }
4470
4471         cb = container_of(blk_cb, struct raid5_plug_cb, cb);
4472
4473         if (cb->list.next == NULL) {
4474                 int i;
4475                 INIT_LIST_HEAD(&cb->list);
4476                 for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
4477                         INIT_LIST_HEAD(cb->temp_inactive_list + i);
4478         }
4479
4480         if (!test_and_set_bit(STRIPE_ON_UNPLUG_LIST, &sh->state))
4481                 list_add_tail(&sh->lru, &cb->list);
4482         else
4483                 release_stripe(sh);
4484 }
4485
4486 static void make_discard_request(struct mddev *mddev, struct bio *bi)
4487 {
4488         struct r5conf *conf = mddev->private;
4489         sector_t logical_sector, last_sector;
4490         struct stripe_head *sh;
4491         int remaining;
4492         int stripe_sectors;
4493
4494         if (mddev->reshape_position != MaxSector)
4495                 /* Skip discard while reshape is happening */
4496                 return;
4497
4498         logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4499         last_sector = bi->bi_iter.bi_sector + (bi->bi_iter.bi_size>>9);
4500
4501         bi->bi_next = NULL;
4502         bi->bi_phys_segments = 1; /* over-loaded to count active stripes */
4503
4504         stripe_sectors = conf->chunk_sectors *
4505                 (conf->raid_disks - conf->max_degraded);
4506         logical_sector = DIV_ROUND_UP_SECTOR_T(logical_sector,
4507                                                stripe_sectors);
4508         sector_div(last_sector, stripe_sectors);
4509
4510         logical_sector *= conf->chunk_sectors;
4511         last_sector *= conf->chunk_sectors;
4512
4513         for (; logical_sector < last_sector;
4514              logical_sector += STRIPE_SECTORS) {
4515                 DEFINE_WAIT(w);
4516                 int d;
4517         again:
4518                 sh = get_active_stripe(conf, logical_sector, 0, 0, 0);
4519                 prepare_to_wait(&conf->wait_for_overlap, &w,
4520                                 TASK_UNINTERRUPTIBLE);
4521                 set_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
4522                 if (test_bit(STRIPE_SYNCING, &sh->state)) {
4523                         release_stripe(sh);
4524                         schedule();
4525                         goto again;
4526                 }
4527                 clear_bit(R5_Overlap, &sh->dev[sh->pd_idx].flags);
4528                 spin_lock_irq(&sh->stripe_lock);
4529                 for (d = 0; d < conf->raid_disks; d++) {
4530                         if (d == sh->pd_idx || d == sh->qd_idx)
4531                                 continue;
4532                         if (sh->dev[d].towrite || sh->dev[d].toread) {
4533                                 set_bit(R5_Overlap, &sh->dev[d].flags);
4534                                 spin_unlock_irq(&sh->stripe_lock);
4535                                 release_stripe(sh);
4536                                 schedule();
4537                                 goto again;
4538                         }
4539                 }
4540                 set_bit(STRIPE_DISCARD, &sh->state);
4541                 finish_wait(&conf->wait_for_overlap, &w);
4542                 for (d = 0; d < conf->raid_disks; d++) {
4543                         if (d == sh->pd_idx || d == sh->qd_idx)
4544                                 continue;
4545                         sh->dev[d].towrite = bi;
4546                         set_bit(R5_OVERWRITE, &sh->dev[d].flags);
4547                         raid5_inc_bi_active_stripes(bi);
4548                 }
4549                 spin_unlock_irq(&sh->stripe_lock);
4550                 if (conf->mddev->bitmap) {
4551                         for (d = 0;
4552                              d < conf->raid_disks - conf->max_degraded;
4553                              d++)
4554                                 bitmap_startwrite(mddev->bitmap,
4555                                                   sh->sector,
4556                                                   STRIPE_SECTORS,
4557                                                   0);
4558                         sh->bm_seq = conf->seq_flush + 1;
4559                         set_bit(STRIPE_BIT_DELAY, &sh->state);
4560                 }
4561
4562                 set_bit(STRIPE_HANDLE, &sh->state);
4563                 clear_bit(STRIPE_DELAYED, &sh->state);
4564                 if (!test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4565                         atomic_inc(&conf->preread_active_stripes);
4566                 release_stripe_plug(mddev, sh);
4567         }
4568
4569         remaining = raid5_dec_bi_active_stripes(bi);
4570         if (remaining == 0) {
4571                 md_write_end(mddev);
4572                 bio_endio(bi, 0);
4573         }
4574 }
4575
4576 static void make_request(struct mddev *mddev, struct bio * bi)
4577 {
4578         struct r5conf *conf = mddev->private;
4579         int dd_idx;
4580         sector_t new_sector;
4581         sector_t logical_sector, last_sector;
4582         struct stripe_head *sh;
4583         const int rw = bio_data_dir(bi);
4584         int remaining;
4585         DEFINE_WAIT(w);
4586         bool do_prepare;
4587
4588         if (unlikely(bi->bi_rw & REQ_FLUSH)) {
4589                 md_flush_request(mddev, bi);
4590                 return;
4591         }
4592
4593         md_write_start(mddev, bi);
4594
4595         if (rw == READ &&
4596              mddev->reshape_position == MaxSector &&
4597              chunk_aligned_read(mddev,bi))
4598                 return;
4599
4600         if (unlikely(bi->bi_rw & REQ_DISCARD)) {
4601                 make_discard_request(mddev, bi);
4602                 return;
4603         }
4604
4605         logical_sector = bi->bi_iter.bi_sector & ~((sector_t)STRIPE_SECTORS-1);
4606         last_sector = bio_end_sector(bi);
4607         bi->bi_next = NULL;
4608         bi->bi_phys_segments = 1;       /* over-loaded to count active stripes */
4609
4610         prepare_to_wait(&conf->wait_for_overlap, &w, TASK_UNINTERRUPTIBLE);
4611         for (;logical_sector < last_sector; logical_sector += STRIPE_SECTORS) {
4612                 int previous;
4613                 int seq;
4614
4615                 do_prepare = false;
4616         retry:
4617                 seq = read_seqcount_begin(&conf->gen_lock);
4618                 previous = 0;
4619                 if (do_prepare)
4620                         prepare_to_wait(&conf->wait_for_overlap, &w,
4621                                 TASK_UNINTERRUPTIBLE);
4622                 if (unlikely(conf->reshape_progress != MaxSector)) {
4623                         /* spinlock is needed as reshape_progress may be
4624                          * 64bit on a 32bit platform, and so it might be
4625                          * possible to see a half-updated value
4626                          * Of course reshape_progress could change after
4627                          * the lock is dropped, so once we get a reference
4628                          * to the stripe that we think it is, we will have
4629                          * to check again.
4630                          */
4631                         spin_lock_irq(&conf->device_lock);
4632                         if (mddev->reshape_backwards
4633                             ? logical_sector < conf->reshape_progress
4634                             : logical_sector >= conf->reshape_progress) {
4635                                 previous = 1;
4636                         } else {
4637                                 if (mddev->reshape_backwards
4638                                     ? logical_sector < conf->reshape_safe
4639                                     : logical_sector >= conf->reshape_safe) {
4640                                         spin_unlock_irq(&conf->device_lock);
4641                                         schedule();
4642                                         do_prepare = true;
4643                                         goto retry;
4644                                 }
4645                         }
4646                         spin_unlock_irq(&conf->device_lock);
4647                 }
4648
4649                 new_sector = raid5_compute_sector(conf, logical_sector,
4650                                                   previous,
4651                                                   &dd_idx, NULL);
4652                 pr_debug("raid456: make_request, sector %llu logical %llu\n",
4653                         (unsigned long long)new_sector,
4654                         (unsigned long long)logical_sector);
4655
4656                 sh = get_active_stripe(conf, new_sector, previous,
4657                                        (bi->bi_rw&RWA_MASK), 0);
4658                 if (sh) {
4659                         if (unlikely(previous)) {
4660                                 /* expansion might have moved on while waiting for a
4661                                  * stripe, so we must do the range check again.
4662                                  * Expansion could still move past after this
4663                                  * test, but as we are holding a reference to
4664                                  * 'sh', we know that if that happens,
4665                                  *  STRIPE_EXPANDING will get set and the expansion
4666                                  * won't proceed until we finish with the stripe.
4667                                  */
4668                                 int must_retry = 0;
4669                                 spin_lock_irq(&conf->device_lock);
4670                                 if (mddev->reshape_backwards
4671                                     ? logical_sector >= conf->reshape_progress
4672                                     : logical_sector < conf->reshape_progress)
4673                                         /* mismatch, need to try again */
4674                                         must_retry = 1;
4675                                 spin_unlock_irq(&conf->device_lock);
4676                                 if (must_retry) {
4677                                         release_stripe(sh);
4678                                         schedule();
4679                                         do_prepare = true;
4680                                         goto retry;
4681                                 }
4682                         }
4683                         if (read_seqcount_retry(&conf->gen_lock, seq)) {
4684                                 /* Might have got the wrong stripe_head
4685                                  * by accident
4686                                  */
4687                                 release_stripe(sh);
4688                                 goto retry;
4689                         }
4690
4691                         if (rw == WRITE &&
4692                             logical_sector >= mddev->suspend_lo &&
4693                             logical_sector < mddev->suspend_hi) {
4694                                 release_stripe(sh);
4695                                 /* As the suspend_* range is controlled by
4696                                  * userspace, we want an interruptible
4697                                  * wait.
4698                                  */
4699                                 flush_signals(current);
4700                                 prepare_to_wait(&conf->wait_for_overlap,
4701                                                 &w, TASK_INTERRUPTIBLE);
4702                                 if (logical_sector >= mddev->suspend_lo &&
4703                                     logical_sector < mddev->suspend_hi) {
4704                                         schedule();
4705                                         do_prepare = true;
4706                                 }
4707                                 goto retry;
4708                         }
4709
4710                         if (test_bit(STRIPE_EXPANDING, &sh->state) ||
4711                             !add_stripe_bio(sh, bi, dd_idx, rw)) {
4712                                 /* Stripe is busy expanding or
4713                                  * add failed due to overlap.  Flush everything
4714                                  * and wait a while
4715                                  */
4716                                 md_wakeup_thread(mddev->thread);
4717                                 release_stripe(sh);
4718                                 schedule();
4719                                 do_prepare = true;
4720                                 goto retry;
4721                         }
4722                         set_bit(STRIPE_HANDLE, &sh->state);
4723                         clear_bit(STRIPE_DELAYED, &sh->state);
4724                         if ((bi->bi_rw & REQ_SYNC) &&
4725                             !test_and_set_bit(STRIPE_PREREAD_ACTIVE, &sh->state))
4726                                 atomic_inc(&conf->preread_active_stripes);
4727                         release_stripe_plug(mddev, sh);
4728                 } else {
4729                         /* cannot get stripe for read-ahead, just give-up */
4730                         clear_bit(BIO_UPTODATE, &bi->bi_flags);
4731                         break;
4732                 }
4733         }
4734         finish_wait(&conf->wait_for_overlap, &w);
4735
4736         remaining = raid5_dec_bi_active_stripes(bi);
4737         if (remaining == 0) {
4738
4739                 if ( rw == WRITE )
4740                         md_write_end(mddev);
4741
4742                 trace_block_bio_complete(bdev_get_queue(bi->bi_bdev),
4743                                          bi, 0);
4744                 bio_endio(bi, 0);
4745         }
4746 }
4747
4748 static sector_t raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks);
4749
4750 static sector_t reshape_request(struct mddev *mddev, sector_t sector_nr, int *skipped)
4751 {
4752         /* reshaping is quite different to recovery/resync so it is
4753          * handled quite separately ... here.
4754          *
4755          * On each call to sync_request, we gather one chunk worth of
4756          * destination stripes and flag them as expanding.
4757          * Then we find all the source stripes and request reads.
4758          * As the reads complete, handle_stripe will copy the data
4759          * into the destination stripe and release that stripe.
4760          */
4761         struct r5conf *conf = mddev->private;
4762         struct stripe_head *sh;
4763         sector_t first_sector, last_sector;
4764         int raid_disks = conf->previous_raid_disks;
4765         int data_disks = raid_disks - conf->max_degraded;
4766         int new_data_disks = conf->raid_disks - conf->max_degraded;
4767         int i;
4768         int dd_idx;
4769         sector_t writepos, readpos, safepos;
4770         sector_t stripe_addr;
4771         int reshape_sectors;
4772         struct list_head stripes;
4773
4774         if (sector_nr == 0) {
4775                 /* If restarting in the middle, skip the initial sectors */
4776                 if (mddev->reshape_backwards &&
4777                     conf->reshape_progress < raid5_size(mddev, 0, 0)) {
4778                         sector_nr = raid5_size(mddev, 0, 0)
4779                                 - conf->reshape_progress;
4780                 } else if (!mddev->reshape_backwards &&
4781                            conf->reshape_progress > 0)
4782                         sector_nr = conf->reshape_progress;
4783                 sector_div(sector_nr, new_data_disks);
4784                 if (sector_nr) {
4785                         mddev->curr_resync_completed = sector_nr;
4786                         sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4787                         *skipped = 1;
4788                         return sector_nr;
4789                 }
4790         }
4791
4792         /* We need to process a full chunk at a time.
4793          * If old and new chunk sizes differ, we need to process the
4794          * largest of these
4795          */
4796         if (mddev->new_chunk_sectors > mddev->chunk_sectors)
4797                 reshape_sectors = mddev->new_chunk_sectors;
4798         else
4799                 reshape_sectors = mddev->chunk_sectors;
4800
4801         /* We update the metadata at least every 10 seconds, or when
4802          * the data about to be copied would over-write the source of
4803          * the data at the front of the range.  i.e. one new_stripe
4804          * along from reshape_progress new_maps to after where
4805          * reshape_safe old_maps to
4806          */
4807         writepos = conf->reshape_progress;
4808         sector_div(writepos, new_data_disks);
4809         readpos = conf->reshape_progress;
4810         sector_div(readpos, data_disks);
4811         safepos = conf->reshape_safe;
4812         sector_div(safepos, data_disks);
4813         if (mddev->reshape_backwards) {
4814                 writepos -= min_t(sector_t, reshape_sectors, writepos);
4815                 readpos += reshape_sectors;
4816                 safepos += reshape_sectors;
4817         } else {
4818                 writepos += reshape_sectors;
4819                 readpos -= min_t(sector_t, reshape_sectors, readpos);
4820                 safepos -= min_t(sector_t, reshape_sectors, safepos);
4821         }
4822
4823         /* Having calculated the 'writepos' possibly use it
4824          * to set 'stripe_addr' which is where we will write to.
4825          */
4826         if (mddev->reshape_backwards) {
4827                 BUG_ON(conf->reshape_progress == 0);
4828                 stripe_addr = writepos;
4829                 BUG_ON((mddev->dev_sectors &
4830                         ~((sector_t)reshape_sectors - 1))
4831                        - reshape_sectors - stripe_addr
4832                        != sector_nr);
4833         } else {
4834                 BUG_ON(writepos != sector_nr + reshape_sectors);
4835                 stripe_addr = sector_nr;
4836         }
4837
4838         /* 'writepos' is the most advanced device address we might write.
4839          * 'readpos' is the least advanced device address we might read.
4840          * 'safepos' is the least address recorded in the metadata as having
4841          *     been reshaped.
4842          * If there is a min_offset_diff, these are adjusted either by
4843          * increasing the safepos/readpos if diff is negative, or
4844          * increasing writepos if diff is positive.
4845          * If 'readpos' is then behind 'writepos', there is no way that we can
4846          * ensure safety in the face of a crash - that must be done by userspace
4847          * making a backup of the data.  So in that case there is no particular
4848          * rush to update metadata.
4849          * Otherwise if 'safepos' is behind 'writepos', then we really need to
4850          * update the metadata to advance 'safepos' to match 'readpos' so that
4851          * we can be safe in the event of a crash.
4852          * So we insist on updating metadata if safepos is behind writepos and
4853          * readpos is beyond writepos.
4854          * In any case, update the metadata every 10 seconds.
4855          * Maybe that number should be configurable, but I'm not sure it is
4856          * worth it.... maybe it could be a multiple of safemode_delay???
4857          */
4858         if (conf->min_offset_diff < 0) {
4859                 safepos += -conf->min_offset_diff;
4860                 readpos += -conf->min_offset_diff;
4861         } else
4862                 writepos += conf->min_offset_diff;
4863
4864         if ((mddev->reshape_backwards
4865              ? (safepos > writepos && readpos < writepos)
4866              : (safepos < writepos && readpos > writepos)) ||
4867             time_after(jiffies, conf->reshape_checkpoint + 10*HZ)) {
4868                 /* Cannot proceed until we've updated the superblock... */
4869                 wait_event(conf->wait_for_overlap,
4870                            atomic_read(&conf->reshape_stripes)==0
4871                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
4872                 if (atomic_read(&conf->reshape_stripes) != 0)
4873                         return 0;
4874                 mddev->reshape_position = conf->reshape_progress;
4875                 mddev->curr_resync_completed = sector_nr;
4876                 conf->reshape_checkpoint = jiffies;
4877                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
4878                 md_wakeup_thread(mddev->thread);
4879                 wait_event(mddev->sb_wait, mddev->flags == 0 ||
4880                            test_bit(MD_RECOVERY_INTR, &mddev->recovery));
4881                 if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
4882                         return 0;
4883                 spin_lock_irq(&conf->device_lock);
4884                 conf->reshape_safe = mddev->reshape_position;
4885                 spin_unlock_irq(&conf->device_lock);
4886                 wake_up(&conf->wait_for_overlap);
4887                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4888         }
4889
4890         INIT_LIST_HEAD(&stripes);
4891         for (i = 0; i < reshape_sectors; i += STRIPE_SECTORS) {
4892                 int j;
4893                 int skipped_disk = 0;
4894                 sh = get_active_stripe(conf, stripe_addr+i, 0, 0, 1);
4895                 set_bit(STRIPE_EXPANDING, &sh->state);
4896                 atomic_inc(&conf->reshape_stripes);
4897                 /* If any of this stripe is beyond the end of the old
4898                  * array, then we need to zero those blocks
4899                  */
4900                 for (j=sh->disks; j--;) {
4901                         sector_t s;
4902                         if (j == sh->pd_idx)
4903                                 continue;
4904                         if (conf->level == 6 &&
4905                             j == sh->qd_idx)
4906                                 continue;
4907                         s = compute_blocknr(sh, j, 0);
4908                         if (s < raid5_size(mddev, 0, 0)) {
4909                                 skipped_disk = 1;
4910                                 continue;
4911                         }
4912                         memset(page_address(sh->dev[j].page), 0, STRIPE_SIZE);
4913                         set_bit(R5_Expanded, &sh->dev[j].flags);
4914                         set_bit(R5_UPTODATE, &sh->dev[j].flags);
4915                 }
4916                 if (!skipped_disk) {
4917                         set_bit(STRIPE_EXPAND_READY, &sh->state);
4918                         set_bit(STRIPE_HANDLE, &sh->state);
4919                 }
4920                 list_add(&sh->lru, &stripes);
4921         }
4922         spin_lock_irq(&conf->device_lock);
4923         if (mddev->reshape_backwards)
4924                 conf->reshape_progress -= reshape_sectors * new_data_disks;
4925         else
4926                 conf->reshape_progress += reshape_sectors * new_data_disks;
4927         spin_unlock_irq(&conf->device_lock);
4928         /* Ok, those stripe are ready. We can start scheduling
4929          * reads on the source stripes.
4930          * The source stripes are determined by mapping the first and last
4931          * block on the destination stripes.
4932          */
4933         first_sector =
4934                 raid5_compute_sector(conf, stripe_addr*(new_data_disks),
4935                                      1, &dd_idx, NULL);
4936         last_sector =
4937                 raid5_compute_sector(conf, ((stripe_addr+reshape_sectors)
4938                                             * new_data_disks - 1),
4939                                      1, &dd_idx, NULL);
4940         if (last_sector >= mddev->dev_sectors)
4941                 last_sector = mddev->dev_sectors - 1;
4942         while (first_sector <= last_sector) {
4943                 sh = get_active_stripe(conf, first_sector, 1, 0, 1);
4944                 set_bit(STRIPE_EXPAND_SOURCE, &sh->state);
4945                 set_bit(STRIPE_HANDLE, &sh->state);
4946                 release_stripe(sh);
4947                 first_sector += STRIPE_SECTORS;
4948         }
4949         /* Now that the sources are clearly marked, we can release
4950          * the destination stripes
4951          */
4952         while (!list_empty(&stripes)) {
4953                 sh = list_entry(stripes.next, struct stripe_head, lru);
4954                 list_del_init(&sh->lru);
4955                 release_stripe(sh);
4956         }
4957         /* If this takes us to the resync_max point where we have to pause,
4958          * then we need to write out the superblock.
4959          */
4960         sector_nr += reshape_sectors;
4961         if ((sector_nr - mddev->curr_resync_completed) * 2
4962             >= mddev->resync_max - mddev->curr_resync_completed) {
4963                 /* Cannot proceed until we've updated the superblock... */
4964                 wait_event(conf->wait_for_overlap,
4965                            atomic_read(&conf->reshape_stripes) == 0
4966                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
4967                 if (atomic_read(&conf->reshape_stripes) != 0)
4968                         goto ret;
4969                 mddev->reshape_position = conf->reshape_progress;
4970                 mddev->curr_resync_completed = sector_nr;
4971                 conf->reshape_checkpoint = jiffies;
4972                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
4973                 md_wakeup_thread(mddev->thread);
4974                 wait_event(mddev->sb_wait,
4975                            !test_bit(MD_CHANGE_DEVS, &mddev->flags)
4976                            || test_bit(MD_RECOVERY_INTR, &mddev->recovery));
4977                 if (test_bit(MD_RECOVERY_INTR, &mddev->recovery))
4978                         goto ret;
4979                 spin_lock_irq(&conf->device_lock);
4980                 conf->reshape_safe = mddev->reshape_position;
4981                 spin_unlock_irq(&conf->device_lock);
4982                 wake_up(&conf->wait_for_overlap);
4983                 sysfs_notify(&mddev->kobj, NULL, "sync_completed");
4984         }
4985 ret:
4986         return reshape_sectors;
4987 }
4988
4989 /* FIXME go_faster isn't used */
4990 static inline sector_t sync_request(struct mddev *mddev, sector_t sector_nr, int *skipped, int go_faster)
4991 {
4992         struct r5conf *conf = mddev->private;
4993         struct stripe_head *sh;
4994         sector_t max_sector = mddev->dev_sectors;
4995         sector_t sync_blocks;
4996         int still_degraded = 0;
4997         int i;
4998
4999         if (sector_nr >= max_sector) {
5000                 /* just being told to finish up .. nothing much to do */
5001
5002                 if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery)) {
5003                         end_reshape(conf);
5004                         return 0;
5005                 }
5006
5007                 if (mddev->curr_resync < max_sector) /* aborted */
5008                         bitmap_end_sync(mddev->bitmap, mddev->curr_resync,
5009                                         &sync_blocks, 1);
5010                 else /* completed sync */
5011                         conf->fullsync = 0;
5012                 bitmap_close_sync(mddev->bitmap);
5013
5014                 return 0;
5015         }
5016
5017         /* Allow raid5_quiesce to complete */
5018         wait_event(conf->wait_for_overlap, conf->quiesce != 2);
5019
5020         if (test_bit(MD_RECOVERY_RESHAPE, &mddev->recovery))
5021                 return reshape_request(mddev, sector_nr, skipped);
5022
5023         /* No need to check resync_max as we never do more than one
5024          * stripe, and as resync_max will always be on a chunk boundary,
5025          * if the check in md_do_sync didn't fire, there is no chance
5026          * of overstepping resync_max here
5027          */
5028
5029         /* if there is too many failed drives and we are trying
5030          * to resync, then assert that we are finished, because there is
5031          * nothing we can do.
5032          */
5033         if (mddev->degraded >= conf->max_degraded &&
5034             test_bit(MD_RECOVERY_SYNC, &mddev->recovery)) {
5035                 sector_t rv = mddev->dev_sectors - sector_nr;
5036                 *skipped = 1;
5037                 return rv;
5038         }
5039         if (!test_bit(MD_RECOVERY_REQUESTED, &mddev->recovery) &&
5040             !conf->fullsync &&
5041             !bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, 1) &&
5042             sync_blocks >= STRIPE_SECTORS) {
5043                 /* we can skip this block, and probably more */
5044                 sync_blocks /= STRIPE_SECTORS;
5045                 *skipped = 1;
5046                 return sync_blocks * STRIPE_SECTORS; /* keep things rounded to whole stripes */
5047         }
5048
5049         bitmap_cond_end_sync(mddev->bitmap, sector_nr);
5050
5051         sh = get_active_stripe(conf, sector_nr, 0, 1, 0);
5052         if (sh == NULL) {
5053                 sh = get_active_stripe(conf, sector_nr, 0, 0, 0);
5054                 /* make sure we don't swamp the stripe cache if someone else
5055                  * is trying to get access
5056                  */
5057                 schedule_timeout_uninterruptible(1);
5058         }
5059         /* Need to check if array will still be degraded after recovery/resync
5060          * We don't need to check the 'failed' flag as when that gets set,
5061          * recovery aborts.
5062          */
5063         for (i = 0; i < conf->raid_disks; i++)
5064                 if (conf->disks[i].rdev == NULL)
5065                         still_degraded = 1;
5066
5067         bitmap_start_sync(mddev->bitmap, sector_nr, &sync_blocks, still_degraded);
5068
5069         set_bit(STRIPE_SYNC_REQUESTED, &sh->state);
5070         set_bit(STRIPE_HANDLE, &sh->state);
5071
5072         release_stripe(sh);
5073
5074         return STRIPE_SECTORS;
5075 }
5076
5077 static int  retry_aligned_read(struct r5conf *conf, struct bio *raid_bio)
5078 {
5079         /* We may not be able to submit a whole bio at once as there
5080          * may not be enough stripe_heads available.
5081          * We cannot pre-allocate enough stripe_heads as we may need
5082          * more than exist in the cache (if we allow ever large chunks).
5083          * So we do one stripe head at a time and record in
5084          * ->bi_hw_segments how many have been done.
5085          *
5086          * We *know* that this entire raid_bio is in one chunk, so
5087          * it will be only one 'dd_idx' and only need one call to raid5_compute_sector.
5088          */
5089         struct stripe_head *sh;
5090         int dd_idx;
5091         sector_t sector, logical_sector, last_sector;
5092         int scnt = 0;
5093         int remaining;
5094         int handled = 0;
5095
5096         logical_sector = raid_bio->bi_iter.bi_sector &
5097                 ~((sector_t)STRIPE_SECTORS-1);
5098         sector = raid5_compute_sector(conf, logical_sector,
5099                                       0, &dd_idx, NULL);
5100         last_sector = bio_end_sector(raid_bio);
5101
5102         for (; logical_sector < last_sector;
5103              logical_sector += STRIPE_SECTORS,
5104                      sector += STRIPE_SECTORS,
5105                      scnt++) {
5106
5107                 if (scnt < raid5_bi_processed_stripes(raid_bio))
5108                         /* already done this stripe */
5109                         continue;
5110
5111                 sh = get_active_stripe(conf, sector, 0, 1, 1);
5112
5113                 if (!sh) {
5114                         /* failed to get a stripe - must wait */
5115                         raid5_set_bi_processed_stripes(raid_bio, scnt);
5116                         conf->retry_read_aligned = raid_bio;
5117                         return handled;
5118                 }
5119
5120                 if (!add_stripe_bio(sh, raid_bio, dd_idx, 0)) {
5121                         release_stripe(sh);
5122                         raid5_set_bi_processed_stripes(raid_bio, scnt);
5123                         conf->retry_read_aligned = raid_bio;
5124                         return handled;
5125                 }
5126
5127                 set_bit(R5_ReadNoMerge, &sh->dev[dd_idx].flags);
5128                 handle_stripe(sh);
5129                 release_stripe(sh);
5130                 handled++;
5131         }
5132         remaining = raid5_dec_bi_active_stripes(raid_bio);
5133         if (remaining == 0) {
5134                 trace_block_bio_complete(bdev_get_queue(raid_bio->bi_bdev),
5135                                          raid_bio, 0);
5136                 bio_endio(raid_bio, 0);
5137         }
5138         if (atomic_dec_and_test(&conf->active_aligned_reads))
5139                 wake_up(&conf->wait_for_stripe);
5140         return handled;
5141 }
5142
5143 static int handle_active_stripes(struct r5conf *conf, int group,
5144                                  struct r5worker *worker,
5145                                  struct list_head *temp_inactive_list)
5146 {
5147         struct stripe_head *batch[MAX_STRIPE_BATCH], *sh;
5148         int i, batch_size = 0, hash;
5149         bool release_inactive = false;
5150
5151         while (batch_size < MAX_STRIPE_BATCH &&
5152                         (sh = __get_priority_stripe(conf, group)) != NULL)
5153                 batch[batch_size++] = sh;
5154
5155         if (batch_size == 0) {
5156                 for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5157                         if (!list_empty(temp_inactive_list + i))
5158                                 break;
5159                 if (i == NR_STRIPE_HASH_LOCKS)
5160                         return batch_size;
5161                 release_inactive = true;
5162         }
5163         spin_unlock_irq(&conf->device_lock);
5164
5165         release_inactive_stripe_list(conf, temp_inactive_list,
5166                                      NR_STRIPE_HASH_LOCKS);
5167
5168         if (release_inactive) {
5169                 spin_lock_irq(&conf->device_lock);
5170                 return 0;
5171         }
5172
5173         for (i = 0; i < batch_size; i++)
5174                 handle_stripe(batch[i]);
5175
5176         cond_resched();
5177
5178         spin_lock_irq(&conf->device_lock);
5179         for (i = 0; i < batch_size; i++) {
5180                 hash = batch[i]->hash_lock_index;
5181                 __release_stripe(conf, batch[i], &temp_inactive_list[hash]);
5182         }
5183         return batch_size;
5184 }
5185
5186 static void raid5_do_work(struct work_struct *work)
5187 {
5188         struct r5worker *worker = container_of(work, struct r5worker, work);
5189         struct r5worker_group *group = worker->group;
5190         struct r5conf *conf = group->conf;
5191         int group_id = group - conf->worker_groups;
5192         int handled;
5193         struct blk_plug plug;
5194
5195         pr_debug("+++ raid5worker active\n");
5196
5197         blk_start_plug(&plug);
5198         handled = 0;
5199         spin_lock_irq(&conf->device_lock);
5200         while (1) {
5201                 int batch_size, released;
5202
5203                 released = release_stripe_list(conf, worker->temp_inactive_list);
5204
5205                 batch_size = handle_active_stripes(conf, group_id, worker,
5206                                                    worker->temp_inactive_list);
5207                 worker->working = false;
5208                 if (!batch_size && !released)
5209                         break;
5210                 handled += batch_size;
5211         }
5212         pr_debug("%d stripes handled\n", handled);
5213
5214         spin_unlock_irq(&conf->device_lock);
5215         blk_finish_plug(&plug);
5216
5217         pr_debug("--- raid5worker inactive\n");
5218 }
5219
5220 /*
5221  * This is our raid5 kernel thread.
5222  *
5223  * We scan the hash table for stripes which can be handled now.
5224  * During the scan, completed stripes are saved for us by the interrupt
5225  * handler, so that they will not have to wait for our next wakeup.
5226  */
5227 static void raid5d(struct md_thread *thread)
5228 {
5229         struct mddev *mddev = thread->mddev;
5230         struct r5conf *conf = mddev->private;
5231         int handled;
5232         struct blk_plug plug;
5233
5234         pr_debug("+++ raid5d active\n");
5235
5236         md_check_recovery(mddev);
5237
5238         blk_start_plug(&plug);
5239         handled = 0;
5240         spin_lock_irq(&conf->device_lock);
5241         while (1) {
5242                 struct bio *bio;
5243                 int batch_size, released;
5244
5245                 released = release_stripe_list(conf, conf->temp_inactive_list);
5246
5247                 if (
5248                     !list_empty(&conf->bitmap_list)) {
5249                         /* Now is a good time to flush some bitmap updates */
5250                         conf->seq_flush++;
5251                         spin_unlock_irq(&conf->device_lock);
5252                         bitmap_unplug(mddev->bitmap);
5253                         spin_lock_irq(&conf->device_lock);
5254                         conf->seq_write = conf->seq_flush;
5255                         activate_bit_delay(conf, conf->temp_inactive_list);
5256                 }
5257                 raid5_activate_delayed(conf);
5258
5259                 while ((bio = remove_bio_from_retry(conf))) {
5260                         int ok;
5261                         spin_unlock_irq(&conf->device_lock);
5262                         ok = retry_aligned_read(conf, bio);
5263                         spin_lock_irq(&conf->device_lock);
5264                         if (!ok)
5265                                 break;
5266                         handled++;
5267                 }
5268
5269                 batch_size = handle_active_stripes(conf, ANY_GROUP, NULL,
5270                                                    conf->temp_inactive_list);
5271                 if (!batch_size && !released)
5272                         break;
5273                 handled += batch_size;
5274
5275                 if (mddev->flags & ~(1<<MD_CHANGE_PENDING)) {
5276                         spin_unlock_irq(&conf->device_lock);
5277                         md_check_recovery(mddev);
5278                         spin_lock_irq(&conf->device_lock);
5279                 }
5280         }
5281         pr_debug("%d stripes handled\n", handled);
5282
5283         spin_unlock_irq(&conf->device_lock);
5284
5285         async_tx_issue_pending_all();
5286         blk_finish_plug(&plug);
5287
5288         pr_debug("--- raid5d inactive\n");
5289 }
5290
5291 static ssize_t
5292 raid5_show_stripe_cache_size(struct mddev *mddev, char *page)
5293 {
5294         struct r5conf *conf = mddev->private;
5295         if (conf)
5296                 return sprintf(page, "%d\n", conf->max_nr_stripes);
5297         else
5298                 return 0;
5299 }
5300
5301 int
5302 raid5_set_cache_size(struct mddev *mddev, int size)
5303 {
5304         struct r5conf *conf = mddev->private;
5305         int err;
5306         int hash;
5307
5308         if (size <= 16 || size > 32768)
5309                 return -EINVAL;
5310         hash = (conf->max_nr_stripes - 1) % NR_STRIPE_HASH_LOCKS;
5311         while (size < conf->max_nr_stripes) {
5312                 if (drop_one_stripe(conf, hash))
5313                         conf->max_nr_stripes--;
5314                 else
5315                         break;
5316                 hash--;
5317                 if (hash < 0)
5318                         hash = NR_STRIPE_HASH_LOCKS - 1;
5319         }
5320         err = md_allow_write(mddev);
5321         if (err)
5322                 return err;
5323         hash = conf->max_nr_stripes % NR_STRIPE_HASH_LOCKS;
5324         while (size > conf->max_nr_stripes) {
5325                 if (grow_one_stripe(conf, hash))
5326                         conf->max_nr_stripes++;
5327                 else break;
5328                 hash = (hash + 1) % NR_STRIPE_HASH_LOCKS;
5329         }
5330         return 0;
5331 }
5332 EXPORT_SYMBOL(raid5_set_cache_size);
5333
5334 static ssize_t
5335 raid5_store_stripe_cache_size(struct mddev *mddev, const char *page, size_t len)
5336 {
5337         struct r5conf *conf = mddev->private;
5338         unsigned long new;
5339         int err;
5340
5341         if (len >= PAGE_SIZE)
5342                 return -EINVAL;
5343         if (!conf)
5344                 return -ENODEV;
5345
5346         if (kstrtoul(page, 10, &new))
5347                 return -EINVAL;
5348         err = raid5_set_cache_size(mddev, new);
5349         if (err)
5350                 return err;
5351         return len;
5352 }
5353
5354 static struct md_sysfs_entry
5355 raid5_stripecache_size = __ATTR(stripe_cache_size, S_IRUGO | S_IWUSR,
5356                                 raid5_show_stripe_cache_size,
5357                                 raid5_store_stripe_cache_size);
5358
5359 static ssize_t
5360 raid5_show_preread_threshold(struct mddev *mddev, char *page)
5361 {
5362         struct r5conf *conf = mddev->private;
5363         if (conf)
5364                 return sprintf(page, "%d\n", conf->bypass_threshold);
5365         else
5366                 return 0;
5367 }
5368
5369 static ssize_t
5370 raid5_store_preread_threshold(struct mddev *mddev, const char *page, size_t len)
5371 {
5372         struct r5conf *conf = mddev->private;
5373         unsigned long new;
5374         if (len >= PAGE_SIZE)
5375                 return -EINVAL;
5376         if (!conf)
5377                 return -ENODEV;
5378
5379         if (kstrtoul(page, 10, &new))
5380                 return -EINVAL;
5381         if (new > conf->max_nr_stripes)
5382                 return -EINVAL;
5383         conf->bypass_threshold = new;
5384         return len;
5385 }
5386
5387 static struct md_sysfs_entry
5388 raid5_preread_bypass_threshold = __ATTR(preread_bypass_threshold,
5389                                         S_IRUGO | S_IWUSR,
5390                                         raid5_show_preread_threshold,
5391                                         raid5_store_preread_threshold);
5392
5393 static ssize_t
5394 raid5_show_skip_copy(struct mddev *mddev, char *page)
5395 {
5396         struct r5conf *conf = mddev->private;
5397         if (conf)
5398                 return sprintf(page, "%d\n", conf->skip_copy);
5399         else
5400                 return 0;
5401 }
5402
5403 static ssize_t
5404 raid5_store_skip_copy(struct mddev *mddev, const char *page, size_t len)
5405 {
5406         struct r5conf *conf = mddev->private;
5407         unsigned long new;
5408         if (len >= PAGE_SIZE)
5409                 return -EINVAL;
5410         if (!conf)
5411                 return -ENODEV;
5412
5413         if (kstrtoul(page, 10, &new))
5414                 return -EINVAL;
5415         new = !!new;
5416         if (new == conf->skip_copy)
5417                 return len;
5418
5419         mddev_suspend(mddev);
5420         conf->skip_copy = new;
5421         if (new)
5422                 mddev->queue->backing_dev_info.capabilities |=
5423                                                 BDI_CAP_STABLE_WRITES;
5424         else
5425                 mddev->queue->backing_dev_info.capabilities &=
5426                                                 ~BDI_CAP_STABLE_WRITES;
5427         mddev_resume(mddev);
5428         return len;
5429 }
5430
5431 static struct md_sysfs_entry
5432 raid5_skip_copy = __ATTR(skip_copy, S_IRUGO | S_IWUSR,
5433                                         raid5_show_skip_copy,
5434                                         raid5_store_skip_copy);
5435
5436 static ssize_t
5437 stripe_cache_active_show(struct mddev *mddev, char *page)
5438 {
5439         struct r5conf *conf = mddev->private;
5440         if (conf)
5441                 return sprintf(page, "%d\n", atomic_read(&conf->active_stripes));
5442         else
5443                 return 0;
5444 }
5445
5446 static struct md_sysfs_entry
5447 raid5_stripecache_active = __ATTR_RO(stripe_cache_active);
5448
5449 static ssize_t
5450 raid5_show_group_thread_cnt(struct mddev *mddev, char *page)
5451 {
5452         struct r5conf *conf = mddev->private;
5453         if (conf)
5454                 return sprintf(page, "%d\n", conf->worker_cnt_per_group);
5455         else
5456                 return 0;
5457 }
5458
5459 static int alloc_thread_groups(struct r5conf *conf, int cnt,
5460                                int *group_cnt,
5461                                int *worker_cnt_per_group,
5462                                struct r5worker_group **worker_groups);
5463 static ssize_t
5464 raid5_store_group_thread_cnt(struct mddev *mddev, const char *page, size_t len)
5465 {
5466         struct r5conf *conf = mddev->private;
5467         unsigned long new;
5468         int err;
5469         struct r5worker_group *new_groups, *old_groups;
5470         int group_cnt, worker_cnt_per_group;
5471
5472         if (len >= PAGE_SIZE)
5473                 return -EINVAL;
5474         if (!conf)
5475                 return -ENODEV;
5476
5477         if (kstrtoul(page, 10, &new))
5478                 return -EINVAL;
5479
5480         if (new == conf->worker_cnt_per_group)
5481                 return len;
5482
5483         mddev_suspend(mddev);
5484
5485         old_groups = conf->worker_groups;
5486         if (old_groups)
5487                 flush_workqueue(raid5_wq);
5488
5489         err = alloc_thread_groups(conf, new,
5490                                   &group_cnt, &worker_cnt_per_group,
5491                                   &new_groups);
5492         if (!err) {
5493                 spin_lock_irq(&conf->device_lock);
5494                 conf->group_cnt = group_cnt;
5495                 conf->worker_cnt_per_group = worker_cnt_per_group;
5496                 conf->worker_groups = new_groups;
5497                 spin_unlock_irq(&conf->device_lock);
5498
5499                 if (old_groups)
5500                         kfree(old_groups[0].workers);
5501                 kfree(old_groups);
5502         }
5503
5504         mddev_resume(mddev);
5505
5506         if (err)
5507                 return err;
5508         return len;
5509 }
5510
5511 static struct md_sysfs_entry
5512 raid5_group_thread_cnt = __ATTR(group_thread_cnt, S_IRUGO | S_IWUSR,
5513                                 raid5_show_group_thread_cnt,
5514                                 raid5_store_group_thread_cnt);
5515
5516 static struct attribute *raid5_attrs[] =  {
5517         &raid5_stripecache_size.attr,
5518         &raid5_stripecache_active.attr,
5519         &raid5_preread_bypass_threshold.attr,
5520         &raid5_group_thread_cnt.attr,
5521         &raid5_skip_copy.attr,
5522         NULL,
5523 };
5524 static struct attribute_group raid5_attrs_group = {
5525         .name = NULL,
5526         .attrs = raid5_attrs,
5527 };
5528
5529 static int alloc_thread_groups(struct r5conf *conf, int cnt,
5530                                int *group_cnt,
5531                                int *worker_cnt_per_group,
5532                                struct r5worker_group **worker_groups)
5533 {
5534         int i, j, k;
5535         ssize_t size;
5536         struct r5worker *workers;
5537
5538         *worker_cnt_per_group = cnt;
5539         if (cnt == 0) {
5540                 *group_cnt = 0;
5541                 *worker_groups = NULL;
5542                 return 0;
5543         }
5544         *group_cnt = num_possible_nodes();
5545         size = sizeof(struct r5worker) * cnt;
5546         workers = kzalloc(size * *group_cnt, GFP_NOIO);
5547         *worker_groups = kzalloc(sizeof(struct r5worker_group) *
5548                                 *group_cnt, GFP_NOIO);
5549         if (!*worker_groups || !workers) {
5550                 kfree(workers);
5551                 kfree(*worker_groups);
5552                 return -ENOMEM;
5553         }
5554
5555         for (i = 0; i < *group_cnt; i++) {
5556                 struct r5worker_group *group;
5557
5558                 group = &(*worker_groups)[i];
5559                 INIT_LIST_HEAD(&group->handle_list);
5560                 group->conf = conf;
5561                 group->workers = workers + i * cnt;
5562
5563                 for (j = 0; j < cnt; j++) {
5564                         struct r5worker *worker = group->workers + j;
5565                         worker->group = group;
5566                         INIT_WORK(&worker->work, raid5_do_work);
5567
5568                         for (k = 0; k < NR_STRIPE_HASH_LOCKS; k++)
5569                                 INIT_LIST_HEAD(worker->temp_inactive_list + k);
5570                 }
5571         }
5572
5573         return 0;
5574 }
5575
5576 static void free_thread_groups(struct r5conf *conf)
5577 {
5578         if (conf->worker_groups)
5579                 kfree(conf->worker_groups[0].workers);
5580         kfree(conf->worker_groups);
5581         conf->worker_groups = NULL;
5582 }
5583
5584 static sector_t
5585 raid5_size(struct mddev *mddev, sector_t sectors, int raid_disks)
5586 {
5587         struct r5conf *conf = mddev->private;
5588
5589         if (!sectors)
5590                 sectors = mddev->dev_sectors;
5591         if (!raid_disks)
5592                 /* size is defined by the smallest of previous and new size */
5593                 raid_disks = min(conf->raid_disks, conf->previous_raid_disks);
5594
5595         sectors &= ~((sector_t)mddev->chunk_sectors - 1);
5596         sectors &= ~((sector_t)mddev->new_chunk_sectors - 1);
5597         return sectors * (raid_disks - conf->max_degraded);
5598 }
5599
5600 static void free_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
5601 {
5602         safe_put_page(percpu->spare_page);
5603         kfree(percpu->scribble);
5604         percpu->spare_page = NULL;
5605         percpu->scribble = NULL;
5606 }
5607
5608 static int alloc_scratch_buffer(struct r5conf *conf, struct raid5_percpu *percpu)
5609 {
5610         if (conf->level == 6 && !percpu->spare_page)
5611                 percpu->spare_page = alloc_page(GFP_KERNEL);
5612         if (!percpu->scribble)
5613                 percpu->scribble = kmalloc(conf->scribble_len, GFP_KERNEL);
5614
5615         if (!percpu->scribble || (conf->level == 6 && !percpu->spare_page)) {
5616                 free_scratch_buffer(conf, percpu);
5617                 return -ENOMEM;
5618         }
5619
5620         return 0;
5621 }
5622
5623 static void raid5_free_percpu(struct r5conf *conf)
5624 {
5625         unsigned long cpu;
5626
5627         if (!conf->percpu)
5628                 return;
5629
5630 #ifdef CONFIG_HOTPLUG_CPU
5631         unregister_cpu_notifier(&conf->cpu_notify);
5632 #endif
5633
5634         get_online_cpus();
5635         for_each_possible_cpu(cpu)
5636                 free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
5637         put_online_cpus();
5638
5639         free_percpu(conf->percpu);
5640 }
5641
5642 static void free_conf(struct r5conf *conf)
5643 {
5644         free_thread_groups(conf);
5645         shrink_stripes(conf);
5646         raid5_free_percpu(conf);
5647         kfree(conf->disks);
5648         kfree(conf->stripe_hashtbl);
5649         kfree(conf);
5650 }
5651
5652 #ifdef CONFIG_HOTPLUG_CPU
5653 static int raid456_cpu_notify(struct notifier_block *nfb, unsigned long action,
5654                               void *hcpu)
5655 {
5656         struct r5conf *conf = container_of(nfb, struct r5conf, cpu_notify);
5657         long cpu = (long)hcpu;
5658         struct raid5_percpu *percpu = per_cpu_ptr(conf->percpu, cpu);
5659
5660         switch (action) {
5661         case CPU_UP_PREPARE:
5662         case CPU_UP_PREPARE_FROZEN:
5663                 if (alloc_scratch_buffer(conf, percpu)) {
5664                         pr_err("%s: failed memory allocation for cpu%ld\n",
5665                                __func__, cpu);
5666                         return notifier_from_errno(-ENOMEM);
5667                 }
5668                 break;
5669         case CPU_DEAD:
5670         case CPU_DEAD_FROZEN:
5671                 free_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
5672                 break;
5673         default:
5674                 break;
5675         }
5676         return NOTIFY_OK;
5677 }
5678 #endif
5679
5680 static int raid5_alloc_percpu(struct r5conf *conf)
5681 {
5682         unsigned long cpu;
5683         int err = 0;
5684
5685         conf->percpu = alloc_percpu(struct raid5_percpu);
5686         if (!conf->percpu)
5687                 return -ENOMEM;
5688
5689 #ifdef CONFIG_HOTPLUG_CPU
5690         conf->cpu_notify.notifier_call = raid456_cpu_notify;
5691         conf->cpu_notify.priority = 0;
5692         err = register_cpu_notifier(&conf->cpu_notify);
5693         if (err)
5694                 return err;
5695 #endif
5696
5697         get_online_cpus();
5698         for_each_present_cpu(cpu) {
5699                 err = alloc_scratch_buffer(conf, per_cpu_ptr(conf->percpu, cpu));
5700                 if (err) {
5701                         pr_err("%s: failed memory allocation for cpu%ld\n",
5702                                __func__, cpu);
5703                         break;
5704                 }
5705         }
5706         put_online_cpus();
5707
5708         return err;
5709 }
5710
5711 static struct r5conf *setup_conf(struct mddev *mddev)
5712 {
5713         struct r5conf *conf;
5714         int raid_disk, memory, max_disks;
5715         struct md_rdev *rdev;
5716         struct disk_info *disk;
5717         char pers_name[6];
5718         int i;
5719         int group_cnt, worker_cnt_per_group;
5720         struct r5worker_group *new_group;
5721
5722         if (mddev->new_level != 5
5723             && mddev->new_level != 4
5724             && mddev->new_level != 6) {
5725                 printk(KERN_ERR "md/raid:%s: raid level not set to 4/5/6 (%d)\n",
5726                        mdname(mddev), mddev->new_level);
5727                 return ERR_PTR(-EIO);
5728         }
5729         if ((mddev->new_level == 5
5730              && !algorithm_valid_raid5(mddev->new_layout)) ||
5731             (mddev->new_level == 6
5732              && !algorithm_valid_raid6(mddev->new_layout))) {
5733                 printk(KERN_ERR "md/raid:%s: layout %d not supported\n",
5734                        mdname(mddev), mddev->new_layout);
5735                 return ERR_PTR(-EIO);
5736         }
5737         if (mddev->new_level == 6 && mddev->raid_disks < 4) {
5738                 printk(KERN_ERR "md/raid:%s: not enough configured devices (%d, minimum 4)\n",
5739                        mdname(mddev), mddev->raid_disks);
5740                 return ERR_PTR(-EINVAL);
5741         }
5742
5743         if (!mddev->new_chunk_sectors ||
5744             (mddev->new_chunk_sectors << 9) % PAGE_SIZE ||
5745             !is_power_of_2(mddev->new_chunk_sectors)) {
5746                 printk(KERN_ERR "md/raid:%s: invalid chunk size %d\n",
5747                        mdname(mddev), mddev->new_chunk_sectors << 9);
5748                 return ERR_PTR(-EINVAL);
5749         }
5750
5751         conf = kzalloc(sizeof(struct r5conf), GFP_KERNEL);
5752         if (conf == NULL)
5753                 goto abort;
5754         /* Don't enable multi-threading by default*/
5755         if (!alloc_thread_groups(conf, 0, &group_cnt, &worker_cnt_per_group,
5756                                  &new_group)) {
5757                 conf->group_cnt = group_cnt;
5758                 conf->worker_cnt_per_group = worker_cnt_per_group;
5759                 conf->worker_groups = new_group;
5760         } else
5761                 goto abort;
5762         spin_lock_init(&conf->device_lock);
5763         seqcount_init(&conf->gen_lock);
5764         init_waitqueue_head(&conf->wait_for_stripe);
5765         init_waitqueue_head(&conf->wait_for_overlap);
5766         INIT_LIST_HEAD(&conf->handle_list);
5767         INIT_LIST_HEAD(&conf->hold_list);
5768         INIT_LIST_HEAD(&conf->delayed_list);
5769         INIT_LIST_HEAD(&conf->bitmap_list);
5770         init_llist_head(&conf->released_stripes);
5771         atomic_set(&conf->active_stripes, 0);
5772         atomic_set(&conf->preread_active_stripes, 0);
5773         atomic_set(&conf->active_aligned_reads, 0);
5774         conf->bypass_threshold = BYPASS_THRESHOLD;
5775         conf->recovery_disabled = mddev->recovery_disabled - 1;
5776
5777         conf->raid_disks = mddev->raid_disks;
5778         if (mddev->reshape_position == MaxSector)
5779                 conf->previous_raid_disks = mddev->raid_disks;
5780         else
5781                 conf->previous_raid_disks = mddev->raid_disks - mddev->delta_disks;
5782         max_disks = max(conf->raid_disks, conf->previous_raid_disks);
5783         conf->scribble_len = scribble_len(max_disks);
5784
5785         conf->disks = kzalloc(max_disks * sizeof(struct disk_info),
5786                               GFP_KERNEL);
5787         if (!conf->disks)
5788                 goto abort;
5789
5790         conf->mddev = mddev;
5791
5792         if ((conf->stripe_hashtbl = kzalloc(PAGE_SIZE, GFP_KERNEL)) == NULL)
5793                 goto abort;
5794
5795         /* We init hash_locks[0] separately to that it can be used
5796          * as the reference lock in the spin_lock_nest_lock() call
5797          * in lock_all_device_hash_locks_irq in order to convince
5798          * lockdep that we know what we are doing.
5799          */
5800         spin_lock_init(conf->hash_locks);
5801         for (i = 1; i < NR_STRIPE_HASH_LOCKS; i++)
5802                 spin_lock_init(conf->hash_locks + i);
5803
5804         for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5805                 INIT_LIST_HEAD(conf->inactive_list + i);
5806
5807         for (i = 0; i < NR_STRIPE_HASH_LOCKS; i++)
5808                 INIT_LIST_HEAD(conf->temp_inactive_list + i);
5809
5810         conf->level = mddev->new_level;
5811         if (raid5_alloc_percpu(conf) != 0)
5812                 goto abort;
5813
5814         pr_debug("raid456: run(%s) called.\n", mdname(mddev));
5815
5816         rdev_for_each(rdev, mddev) {
5817                 raid_disk = rdev->raid_disk;
5818                 if (raid_disk >= max_disks
5819                     || raid_disk < 0)
5820                         continue;
5821                 disk = conf->disks + raid_disk;
5822
5823                 if (test_bit(Replacement, &rdev->flags)) {
5824                         if (disk->replacement)
5825                                 goto abort;
5826                         disk->replacement = rdev;
5827                 } else {
5828                         if (disk->rdev)
5829                                 goto abort;
5830                         disk->rdev = rdev;
5831                 }
5832
5833                 if (test_bit(In_sync, &rdev->flags)) {
5834                         char b[BDEVNAME_SIZE];
5835                         printk(KERN_INFO "md/raid:%s: device %s operational as raid"
5836                                " disk %d\n",
5837                                mdname(mddev), bdevname(rdev->bdev, b), raid_disk);
5838                 } else if (rdev->saved_raid_disk != raid_disk)
5839                         /* Cannot rely on bitmap to complete recovery */
5840                         conf->fullsync = 1;
5841         }
5842
5843         conf->chunk_sectors = mddev->new_chunk_sectors;
5844         conf->level = mddev->new_level;
5845         if (conf->level == 6)
5846                 conf->max_degraded = 2;
5847         else
5848                 conf->max_degraded = 1;
5849         conf->algorithm = mddev->new_layout;
5850         conf->reshape_progress = mddev->reshape_position;
5851         if (conf->reshape_progress != MaxSector) {
5852                 conf->prev_chunk_sectors = mddev->chunk_sectors;
5853                 conf->prev_algo = mddev->layout;
5854         }
5855
5856         memory = conf->max_nr_stripes * (sizeof(struct stripe_head) +
5857                  max_disks * ((sizeof(struct bio) + PAGE_SIZE))) / 1024;
5858         atomic_set(&conf->empty_inactive_list_nr, NR_STRIPE_HASH_LOCKS);
5859         if (grow_stripes(conf, NR_STRIPES)) {
5860                 printk(KERN_ERR
5861                        "md/raid:%s: couldn't allocate %dkB for buffers\n",
5862                        mdname(mddev), memory);
5863                 goto abort;
5864         } else
5865                 printk(KERN_INFO "md/raid:%s: allocated %dkB\n",
5866                        mdname(mddev), memory);
5867
5868         sprintf(pers_name, "raid%d", mddev->new_level);
5869         conf->thread = md_register_thread(raid5d, mddev, pers_name);
5870         if (!conf->thread) {
5871                 printk(KERN_ERR
5872                        "md/raid:%s: couldn't allocate thread.\n",
5873                        mdname(mddev));
5874                 goto abort;
5875         }
5876
5877         return conf;
5878
5879  abort:
5880         if (conf) {
5881                 free_conf(conf);
5882                 return ERR_PTR(-EIO);
5883         } else
5884                 return ERR_PTR(-ENOMEM);
5885 }
5886
5887 static int only_parity(int raid_disk, int algo, int raid_disks, int max_degraded)
5888 {
5889         switch (algo) {
5890         case ALGORITHM_PARITY_0:
5891                 if (raid_disk < max_degraded)
5892                         return 1;
5893                 break;
5894         case ALGORITHM_PARITY_N:
5895                 if (raid_disk >= raid_disks - max_degraded)
5896                         return 1;
5897                 break;
5898         case ALGORITHM_PARITY_0_6:
5899                 if (raid_disk == 0 ||
5900                     raid_disk == raid_disks - 1)
5901                         return 1;
5902                 break;
5903         case ALGORITHM_LEFT_ASYMMETRIC_6:
5904         case ALGORITHM_RIGHT_ASYMMETRIC_6:
5905         case ALGORITHM_LEFT_SYMMETRIC_6:
5906         case ALGORITHM_RIGHT_SYMMETRIC_6:
5907                 if (raid_disk == raid_disks - 1)
5908                         return 1;
5909         }
5910         return 0;
5911 }
5912
5913 static int run(struct mddev *mddev)
5914 {
5915         struct r5conf *conf;
5916         int working_disks = 0;
5917         int dirty_parity_disks = 0;
5918         struct md_rdev *rdev;
5919         sector_t reshape_offset = 0;
5920         int i;
5921         long long min_offset_diff = 0;
5922         int first = 1;
5923
5924         if (mddev->recovery_cp != MaxSector)
5925                 printk(KERN_NOTICE "md/raid:%s: not clean"
5926                        " -- starting background reconstruction\n",
5927                        mdname(mddev));
5928
5929         rdev_for_each(rdev, mddev) {
5930                 long long diff;
5931                 if (rdev->raid_disk < 0)
5932                         continue;
5933                 diff = (rdev->new_data_offset - rdev->data_offset);
5934                 if (first) {
5935                         min_offset_diff = diff;
5936                         first = 0;
5937                 } else if (mddev->reshape_backwards &&
5938                          diff < min_offset_diff)
5939                         min_offset_diff = diff;
5940                 else if (!mddev->reshape_backwards &&
5941                          diff > min_offset_diff)
5942                         min_offset_diff = diff;
5943         }
5944
5945         if (mddev->reshape_position != MaxSector) {
5946                 /* Check that we can continue the reshape.
5947                  * Difficulties arise if the stripe we would write to
5948                  * next is at or after the stripe we would read from next.
5949                  * For a reshape that changes the number of devices, this
5950                  * is only possible for a very short time, and mdadm makes
5951                  * sure that time appears to have past before assembling
5952                  * the array.  So we fail if that time hasn't passed.
5953                  * For a reshape that keeps the number of devices the same
5954                  * mdadm must be monitoring the reshape can keeping the
5955                  * critical areas read-only and backed up.  It will start
5956                  * the array in read-only mode, so we check for that.
5957                  */
5958                 sector_t here_new, here_old;
5959                 int old_disks;
5960                 int max_degraded = (mddev->level == 6 ? 2 : 1);
5961
5962                 if (mddev->new_level != mddev->level) {
5963                         printk(KERN_ERR "md/raid:%s: unsupported reshape "
5964                                "required - aborting.\n",
5965                                mdname(mddev));
5966                         return -EINVAL;
5967                 }
5968                 old_disks = mddev->raid_disks - mddev->delta_disks;
5969                 /* reshape_position must be on a new-stripe boundary, and one
5970                  * further up in new geometry must map after here in old
5971                  * geometry.
5972                  */
5973                 here_new = mddev->reshape_position;
5974                 if (sector_div(here_new, mddev->new_chunk_sectors *
5975                                (mddev->raid_disks - max_degraded))) {
5976                         printk(KERN_ERR "md/raid:%s: reshape_position not "
5977                                "on a stripe boundary\n", mdname(mddev));
5978                         return -EINVAL;
5979                 }
5980                 reshape_offset = here_new * mddev->new_chunk_sectors;
5981                 /* here_new is the stripe we will write to */
5982                 here_old = mddev->reshape_position;
5983                 sector_div(here_old, mddev->chunk_sectors *
5984                            (old_disks-max_degraded));
5985                 /* here_old is the first stripe that we might need to read
5986                  * from */
5987                 if (mddev->delta_disks == 0) {
5988                         if ((here_new * mddev->new_chunk_sectors !=
5989                              here_old * mddev->chunk_sectors)) {
5990                                 printk(KERN_ERR "md/raid:%s: reshape position is"
5991                                        " confused - aborting\n", mdname(mddev));
5992                                 return -EINVAL;
5993                         }
5994                         /* We cannot be sure it is safe to start an in-place
5995                          * reshape.  It is only safe if user-space is monitoring
5996                          * and taking constant backups.
5997                          * mdadm always starts a situation like this in
5998                          * readonly mode so it can take control before
5999                          * allowing any writes.  So just check for that.
6000                          */
6001                         if (abs(min_offset_diff) >= mddev->chunk_sectors &&
6002                             abs(min_offset_diff) >= mddev->new_chunk_sectors)
6003                                 /* not really in-place - so OK */;
6004                         else if (mddev->ro == 0) {
6005                                 printk(KERN_ERR "md/raid:%s: in-place reshape "
6006                                        "must be started in read-only mode "
6007                                        "- aborting\n",
6008                                        mdname(mddev));
6009                                 return -EINVAL;
6010                         }
6011                 } else if (mddev->reshape_backwards
6012                     ? (here_new * mddev->new_chunk_sectors + min_offset_diff <=
6013                        here_old * mddev->chunk_sectors)
6014                     : (here_new * mddev->new_chunk_sectors >=
6015                        here_old * mddev->chunk_sectors + (-min_offset_diff))) {
6016                         /* Reading from the same stripe as writing to - bad */
6017                         printk(KERN_ERR "md/raid:%s: reshape_position too early for "
6018                                "auto-recovery - aborting.\n",
6019                                mdname(mddev));
6020                         return -EINVAL;
6021                 }
6022                 printk(KERN_INFO "md/raid:%s: reshape will continue\n",
6023                        mdname(mddev));
6024                 /* OK, we should be able to continue; */
6025         } else {
6026                 BUG_ON(mddev->level != mddev->new_level);
6027                 BUG_ON(mddev->layout != mddev->new_layout);
6028                 BUG_ON(mddev->chunk_sectors != mddev->new_chunk_sectors);
6029                 BUG_ON(mddev->delta_disks != 0);
6030         }
6031
6032         if (mddev->private == NULL)
6033                 conf = setup_conf(mddev);
6034         else
6035                 conf = mddev->private;
6036
6037         if (IS_ERR(conf))
6038                 return PTR_ERR(conf);
6039
6040         conf->min_offset_diff = min_offset_diff;
6041         mddev->thread = conf->thread;
6042         conf->thread = NULL;
6043         mddev->private = conf;
6044
6045         for (i = 0; i < conf->raid_disks && conf->previous_raid_disks;
6046              i++) {
6047                 rdev = conf->disks[i].rdev;
6048                 if (!rdev && conf->disks[i].replacement) {
6049                         /* The replacement is all we have yet */
6050                         rdev = conf->disks[i].replacement;
6051                         conf->disks[i].replacement = NULL;
6052                         clear_bit(Replacement, &rdev->flags);
6053                         conf->disks[i].rdev = rdev;
6054                 }
6055                 if (!rdev)
6056                         continue;
6057                 if (conf->disks[i].replacement &&
6058                     conf->reshape_progress != MaxSector) {
6059                         /* replacements and reshape simply do not mix. */
6060                         printk(KERN_ERR "md: cannot handle concurrent "
6061                                "replacement and reshape.\n");
6062                         goto abort;
6063                 }
6064                 if (test_bit(In_sync, &rdev->flags)) {
6065                         working_disks++;
6066                         continue;
6067                 }
6068                 /* This disc is not fully in-sync.  However if it
6069                  * just stored parity (beyond the recovery_offset),
6070                  * when we don't need to be concerned about the
6071                  * array being dirty.
6072                  * When reshape goes 'backwards', we never have
6073                  * partially completed devices, so we only need
6074                  * to worry about reshape going forwards.
6075                  */
6076                 /* Hack because v0.91 doesn't store recovery_offset properly. */
6077                 if (mddev->major_version == 0 &&
6078                     mddev->minor_version > 90)
6079                         rdev->recovery_offset = reshape_offset;
6080
6081                 if (rdev->recovery_offset < reshape_offset) {
6082                         /* We need to check old and new layout */
6083                         if (!only_parity(rdev->raid_disk,
6084                                          conf->algorithm,
6085                                          conf->raid_disks,
6086                                          conf->max_degraded))
6087                                 continue;
6088                 }
6089                 if (!only_parity(rdev->raid_disk,
6090                                  conf->prev_algo,
6091                                  conf->previous_raid_disks,
6092                                  conf->max_degraded))
6093                         continue;
6094                 dirty_parity_disks++;
6095         }
6096
6097         /*
6098          * 0 for a fully functional array, 1 or 2 for a degraded array.
6099          */
6100         mddev->degraded = calc_degraded(conf);
6101
6102         if (has_failed(conf)) {
6103                 printk(KERN_ERR "md/raid:%s: not enough operational devices"
6104                         " (%d/%d failed)\n",
6105                         mdname(mddev), mddev->degraded, conf->raid_disks);
6106                 goto abort;
6107         }
6108
6109         /* device size must be a multiple of chunk size */
6110         mddev->dev_sectors &= ~(mddev->chunk_sectors - 1);
6111         mddev->resync_max_sectors = mddev->dev_sectors;
6112
6113         if (mddev->degraded > dirty_parity_disks &&
6114             mddev->recovery_cp != MaxSector) {
6115                 if (mddev->ok_start_degraded)
6116                         printk(KERN_WARNING
6117                                "md/raid:%s: starting dirty degraded array"
6118                                " - data corruption possible.\n",
6119                                mdname(mddev));
6120                 else {
6121                         printk(KERN_ERR
6122                                "md/raid:%s: cannot start dirty degraded array.\n",
6123                                mdname(mddev));
6124                         goto abort;
6125                 }
6126         }
6127
6128         if (mddev->degraded == 0)
6129                 printk(KERN_INFO "md/raid:%s: raid level %d active with %d out of %d"
6130                        " devices, algorithm %d\n", mdname(mddev), conf->level,
6131                        mddev->raid_disks-mddev->degraded, mddev->raid_disks,
6132                        mddev->new_layout);
6133         else
6134                 printk(KERN_ALERT "md/raid:%s: raid level %d active with %d"
6135                        " out of %d devices, algorithm %d\n",
6136                        mdname(mddev), conf->level,
6137                        mddev->raid_disks - mddev->degraded,
6138                        mddev->raid_disks, mddev->new_layout);
6139
6140         print_raid5_conf(conf);
6141
6142         if (conf->reshape_progress != MaxSector) {
6143                 conf->reshape_safe = conf->reshape_progress;
6144                 atomic_set(&conf->reshape_stripes, 0);
6145                 clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
6146                 clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
6147                 set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
6148                 set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
6149                 mddev->sync_thread = md_register_thread(md_do_sync, mddev,
6150                                                         "reshape");
6151         }
6152
6153         /* Ok, everything is just fine now */
6154         if (mddev->to_remove == &raid5_attrs_group)
6155                 mddev->to_remove = NULL;
6156         else if (mddev->kobj.sd &&
6157             sysfs_create_group(&mddev->kobj, &raid5_attrs_group))
6158                 printk(KERN_WARNING
6159                        "raid5: failed to create sysfs attributes for %s\n",
6160                        mdname(mddev));
6161         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
6162
6163         if (mddev->queue) {
6164                 int chunk_size;
6165                 bool discard_supported = true;
6166                 /* read-ahead size must cover two whole stripes, which
6167                  * is 2 * (datadisks) * chunksize where 'n' is the
6168                  * number of raid devices
6169                  */
6170                 int data_disks = conf->previous_raid_disks - conf->max_degraded;
6171                 int stripe = data_disks *
6172                         ((mddev->chunk_sectors << 9) / PAGE_SIZE);
6173                 if (mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
6174                         mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
6175
6176                 blk_queue_merge_bvec(mddev->queue, raid5_mergeable_bvec);
6177
6178                 mddev->queue->backing_dev_info.congested_data = mddev;
6179                 mddev->queue->backing_dev_info.congested_fn = raid5_congested;
6180
6181                 chunk_size = mddev->chunk_sectors << 9;
6182                 blk_queue_io_min(mddev->queue, chunk_size);
6183                 blk_queue_io_opt(mddev->queue, chunk_size *
6184                                  (conf->raid_disks - conf->max_degraded));
6185                 mddev->queue->limits.raid_partial_stripes_expensive = 1;
6186                 /*
6187                  * We can only discard a whole stripe. It doesn't make sense to
6188                  * discard data disk but write parity disk
6189                  */
6190                 stripe = stripe * PAGE_SIZE;
6191                 /* Round up to power of 2, as discard handling
6192                  * currently assumes that */
6193                 while ((stripe-1) & stripe)
6194                         stripe = (stripe | (stripe-1)) + 1;
6195                 mddev->queue->limits.discard_alignment = stripe;
6196                 mddev->queue->limits.discard_granularity = stripe;
6197                 /*
6198                  * unaligned part of discard request will be ignored, so can't
6199                  * guarantee discard_zeroes_data
6200                  */
6201                 mddev->queue->limits.discard_zeroes_data = 0;
6202
6203                 blk_queue_max_write_same_sectors(mddev->queue, 0);
6204
6205                 rdev_for_each(rdev, mddev) {
6206                         disk_stack_limits(mddev->gendisk, rdev->bdev,
6207                                           rdev->data_offset << 9);
6208                         disk_stack_limits(mddev->gendisk, rdev->bdev,
6209                                           rdev->new_data_offset << 9);
6210                         /*
6211                          * discard_zeroes_data is required, otherwise data
6212                          * could be lost. Consider a scenario: discard a stripe
6213                          * (the stripe could be inconsistent if
6214                          * discard_zeroes_data is 0); write one disk of the
6215                          * stripe (the stripe could be inconsistent again
6216                          * depending on which disks are used to calculate
6217                          * parity); the disk is broken; The stripe data of this
6218                          * disk is lost.
6219                          */
6220                         if (!blk_queue_discard(bdev_get_queue(rdev->bdev)) ||
6221                             !bdev_get_queue(rdev->bdev)->
6222                                                 limits.discard_zeroes_data)
6223                                 discard_supported = false;
6224                         /* Unfortunately, discard_zeroes_data is not currently
6225                          * a guarantee - just a hint.  So we only allow DISCARD
6226                          * if the sysadmin has confirmed that only safe devices
6227                          * are in use by setting a module parameter.
6228                          */
6229                         if (!devices_handle_discard_safely) {
6230                                 if (discard_supported) {
6231                                         pr_info("md/raid456: discard support disabled due to uncertainty.\n");
6232                                         pr_info("Set raid456.devices_handle_discard_safely=Y to override.\n");
6233                                 }
6234                                 discard_supported = false;
6235                         }
6236                 }
6237
6238                 if (discard_supported &&
6239                    mddev->queue->limits.max_discard_sectors >= stripe &&
6240                    mddev->queue->limits.discard_granularity >= stripe)
6241                         queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
6242                                                 mddev->queue);
6243                 else
6244                         queue_flag_clear_unlocked(QUEUE_FLAG_DISCARD,
6245                                                 mddev->queue);
6246         }
6247
6248         return 0;
6249 abort:
6250         md_unregister_thread(&mddev->thread);
6251         print_raid5_conf(conf);
6252         free_conf(conf);
6253         mddev->private = NULL;
6254         printk(KERN_ALERT "md/raid:%s: failed to run raid set.\n", mdname(mddev));
6255         return -EIO;
6256 }
6257
6258 static int stop(struct mddev *mddev)
6259 {
6260         struct r5conf *conf = mddev->private;
6261
6262         md_unregister_thread(&mddev->thread);
6263         if (mddev->queue)
6264                 mddev->queue->backing_dev_info.congested_fn = NULL;
6265         free_conf(conf);
6266         mddev->private = NULL;
6267         mddev->to_remove = &raid5_attrs_group;
6268         return 0;
6269 }
6270
6271 static void status(struct seq_file *seq, struct mddev *mddev)
6272 {
6273         struct r5conf *conf = mddev->private;
6274         int i;
6275
6276         seq_printf(seq, " level %d, %dk chunk, algorithm %d", mddev->level,
6277                 mddev->chunk_sectors / 2, mddev->layout);
6278         seq_printf (seq, " [%d/%d] [", conf->raid_disks, conf->raid_disks - mddev->degraded);
6279         for (i = 0; i < conf->raid_disks; i++)
6280                 seq_printf (seq, "%s",
6281                                conf->disks[i].rdev &&
6282                                test_bit(In_sync, &conf->disks[i].rdev->flags) ? "U" : "_");
6283         seq_printf (seq, "]");
6284 }
6285
6286 static void print_raid5_conf (struct r5conf *conf)
6287 {
6288         int i;
6289         struct disk_info *tmp;
6290
6291         printk(KERN_DEBUG "RAID conf printout:\n");
6292         if (!conf) {
6293                 printk("(conf==NULL)\n");
6294                 return;
6295         }
6296         printk(KERN_DEBUG " --- level:%d rd:%d wd:%d\n", conf->level,
6297                conf->raid_disks,
6298                conf->raid_disks - conf->mddev->degraded);
6299
6300         for (i = 0; i < conf->raid_disks; i++) {
6301                 char b[BDEVNAME_SIZE];
6302                 tmp = conf->disks + i;
6303                 if (tmp->rdev)
6304                         printk(KERN_DEBUG " disk %d, o:%d, dev:%s\n",
6305                                i, !test_bit(Faulty, &tmp->rdev->flags),
6306                                bdevname(tmp->rdev->bdev, b));
6307         }
6308 }
6309
6310 static int raid5_spare_active(struct mddev *mddev)
6311 {
6312         int i;
6313         struct r5conf *conf = mddev->private;
6314         struct disk_info *tmp;
6315         int count = 0;
6316         unsigned long flags;
6317
6318         for (i = 0; i < conf->raid_disks; i++) {
6319                 tmp = conf->disks + i;
6320                 if (tmp->replacement
6321                     && tmp->replacement->recovery_offset == MaxSector
6322                     && !test_bit(Faulty, &tmp->replacement->flags)
6323                     && !test_and_set_bit(In_sync, &tmp->replacement->flags)) {
6324                         /* Replacement has just become active. */
6325                         if (!tmp->rdev
6326                             || !test_and_clear_bit(In_sync, &tmp->rdev->flags))
6327                                 count++;
6328                         if (tmp->rdev) {
6329                                 /* Replaced device not technically faulty,
6330                                  * but we need to be sure it gets removed
6331                                  * and never re-added.
6332                                  */
6333                                 set_bit(Faulty, &tmp->rdev->flags);
6334                                 sysfs_notify_dirent_safe(
6335                                         tmp->rdev->sysfs_state);
6336                         }
6337                         sysfs_notify_dirent_safe(tmp->replacement->sysfs_state);
6338                 } else if (tmp->rdev
6339                     && tmp->rdev->recovery_offset == MaxSector
6340                     && !test_bit(Faulty, &tmp->rdev->flags)
6341                     && !test_and_set_bit(In_sync, &tmp->rdev->flags)) {
6342                         count++;
6343                         sysfs_notify_dirent_safe(tmp->rdev->sysfs_state);
6344                 }
6345         }
6346         spin_lock_irqsave(&conf->device_lock, flags);
6347         mddev->degraded = calc_degraded(conf);
6348         spin_unlock_irqrestore(&conf->device_lock, flags);
6349         print_raid5_conf(conf);
6350         return count;
6351 }
6352
6353 static int raid5_remove_disk(struct mddev *mddev, struct md_rdev *rdev)
6354 {
6355         struct r5conf *conf = mddev->private;
6356         int err = 0;
6357         int number = rdev->raid_disk;
6358         struct md_rdev **rdevp;
6359         struct disk_info *p = conf->disks + number;
6360
6361         print_raid5_conf(conf);
6362         if (rdev == p->rdev)
6363                 rdevp = &p->rdev;
6364         else if (rdev == p->replacement)
6365                 rdevp = &p->replacement;
6366         else
6367                 return 0;
6368
6369         if (number >= conf->raid_disks &&
6370             conf->reshape_progress == MaxSector)
6371                 clear_bit(In_sync, &rdev->flags);
6372
6373         if (test_bit(In_sync, &rdev->flags) ||
6374             atomic_read(&rdev->nr_pending)) {
6375                 err = -EBUSY;
6376                 goto abort;
6377         }
6378         /* Only remove non-faulty devices if recovery
6379          * isn't possible.
6380          */
6381         if (!test_bit(Faulty, &rdev->flags) &&
6382             mddev->recovery_disabled != conf->recovery_disabled &&
6383             !has_failed(conf) &&
6384             (!p->replacement || p->replacement == rdev) &&
6385             number < conf->raid_disks) {
6386                 err = -EBUSY;
6387                 goto abort;
6388         }
6389         *rdevp = NULL;
6390         synchronize_rcu();
6391         if (atomic_read(&rdev->nr_pending)) {
6392                 /* lost the race, try later */
6393                 err = -EBUSY;
6394                 *rdevp = rdev;
6395         } else if (p->replacement) {
6396                 /* We must have just cleared 'rdev' */
6397                 p->rdev = p->replacement;
6398                 clear_bit(Replacement, &p->replacement->flags);
6399                 smp_mb(); /* Make sure other CPUs may see both as identical
6400                            * but will never see neither - if they are careful
6401                            */
6402                 p->replacement = NULL;
6403                 clear_bit(WantReplacement, &rdev->flags);
6404         } else
6405                 /* We might have just removed the Replacement as faulty-
6406                  * clear the bit just in case
6407                  */
6408                 clear_bit(WantReplacement, &rdev->flags);
6409 abort:
6410
6411         print_raid5_conf(conf);
6412         return err;
6413 }
6414
6415 static int raid5_add_disk(struct mddev *mddev, struct md_rdev *rdev)
6416 {
6417         struct r5conf *conf = mddev->private;
6418         int err = -EEXIST;
6419         int disk;
6420         struct disk_info *p;
6421         int first = 0;
6422         int last = conf->raid_disks - 1;
6423
6424         if (mddev->recovery_disabled == conf->recovery_disabled)
6425                 return -EBUSY;
6426
6427         if (rdev->saved_raid_disk < 0 && has_failed(conf))
6428                 /* no point adding a device */
6429                 return -EINVAL;
6430
6431         if (rdev->raid_disk >= 0)
6432                 first = last = rdev->raid_disk;
6433
6434         /*
6435          * find the disk ... but prefer rdev->saved_raid_disk
6436          * if possible.
6437          */
6438         if (rdev->saved_raid_disk >= 0 &&
6439             rdev->saved_raid_disk >= first &&
6440             conf->disks[rdev->saved_raid_disk].rdev == NULL)
6441                 first = rdev->saved_raid_disk;
6442
6443         for (disk = first; disk <= last; disk++) {
6444                 p = conf->disks + disk;
6445                 if (p->rdev == NULL) {
6446                         clear_bit(In_sync, &rdev->flags);
6447                         rdev->raid_disk = disk;
6448                         err = 0;
6449                         if (rdev->saved_raid_disk != disk)
6450                                 conf->fullsync = 1;
6451                         rcu_assign_pointer(p->rdev, rdev);
6452                         goto out;
6453                 }
6454         }
6455         for (disk = first; disk <= last; disk++) {
6456                 p = conf->disks + disk;
6457                 if (test_bit(WantReplacement, &p->rdev->flags) &&
6458                     p->replacement == NULL) {
6459                         clear_bit(In_sync, &rdev->flags);
6460                         set_bit(Replacement, &rdev->flags);
6461                         rdev->raid_disk = disk;
6462                         err = 0;
6463                         conf->fullsync = 1;
6464                         rcu_assign_pointer(p->replacement, rdev);
6465                         break;
6466                 }
6467         }
6468 out:
6469         print_raid5_conf(conf);
6470         return err;
6471 }
6472
6473 static int raid5_resize(struct mddev *mddev, sector_t sectors)
6474 {
6475         /* no resync is happening, and there is enough space
6476          * on all devices, so we can resize.
6477          * We need to make sure resync covers any new space.
6478          * If the array is shrinking we should possibly wait until
6479          * any io in the removed space completes, but it hardly seems
6480          * worth it.
6481          */
6482         sector_t newsize;
6483         sectors &= ~((sector_t)mddev->chunk_sectors - 1);
6484         newsize = raid5_size(mddev, sectors, mddev->raid_disks);
6485         if (mddev->external_size &&
6486             mddev->array_sectors > newsize)
6487                 return -EINVAL;
6488         if (mddev->bitmap) {
6489                 int ret = bitmap_resize(mddev->bitmap, sectors, 0, 0);
6490                 if (ret)
6491                         return ret;
6492         }
6493         md_set_array_sectors(mddev, newsize);
6494         set_capacity(mddev->gendisk, mddev->array_sectors);
6495         revalidate_disk(mddev->gendisk);
6496         if (sectors > mddev->dev_sectors &&
6497             mddev->recovery_cp > mddev->dev_sectors) {
6498                 mddev->recovery_cp = mddev->dev_sectors;
6499                 set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
6500         }
6501         mddev->dev_sectors = sectors;
6502         mddev->resync_max_sectors = sectors;
6503         return 0;
6504 }
6505
6506 static int check_stripe_cache(struct mddev *mddev)
6507 {
6508         /* Can only proceed if there are plenty of stripe_heads.
6509          * We need a minimum of one full stripe,, and for sensible progress
6510          * it is best to have about 4 times that.
6511          * If we require 4 times, then the default 256 4K stripe_heads will
6512          * allow for chunk sizes up to 256K, which is probably OK.
6513          * If the chunk size is greater, user-space should request more
6514          * stripe_heads first.
6515          */
6516         struct r5conf *conf = mddev->private;
6517         if (((mddev->chunk_sectors << 9) / STRIPE_SIZE) * 4
6518             > conf->max_nr_stripes ||
6519             ((mddev->new_chunk_sectors << 9) / STRIPE_SIZE) * 4
6520             > conf->max_nr_stripes) {
6521                 printk(KERN_WARNING "md/raid:%s: reshape: not enough stripes.  Needed %lu\n",
6522                        mdname(mddev),
6523                        ((max(mddev->chunk_sectors, mddev->new_chunk_sectors) << 9)
6524                         / STRIPE_SIZE)*4);
6525                 return 0;
6526         }
6527         return 1;
6528 }
6529
6530 static int check_reshape(struct mddev *mddev)
6531 {
6532         struct r5conf *conf = mddev->private;
6533
6534         if (mddev->delta_disks == 0 &&
6535             mddev->new_layout == mddev->layout &&
6536             mddev->new_chunk_sectors == mddev->chunk_sectors)
6537                 return 0; /* nothing to do */
6538         if (has_failed(conf))
6539                 return -EINVAL;
6540         if (mddev->delta_disks < 0 && mddev->reshape_position == MaxSector) {
6541                 /* We might be able to shrink, but the devices must
6542                  * be made bigger first.
6543                  * For raid6, 4 is the minimum size.
6544                  * Otherwise 2 is the minimum
6545                  */
6546                 int min = 2;
6547                 if (mddev->level == 6)
6548                         min = 4;
6549                 if (mddev->raid_disks + mddev->delta_disks < min)
6550                         return -EINVAL;
6551         }
6552
6553         if (!check_stripe_cache(mddev))
6554                 return -ENOSPC;
6555
6556         return resize_stripes(conf, (conf->previous_raid_disks
6557                                      + mddev->delta_disks));
6558 }
6559
6560 static int raid5_start_reshape(struct mddev *mddev)
6561 {
6562         struct r5conf *conf = mddev->private;
6563         struct md_rdev *rdev;
6564         int spares = 0;
6565         unsigned long flags;
6566
6567         if (test_bit(MD_RECOVERY_RUNNING, &mddev->recovery))
6568                 return -EBUSY;
6569
6570         if (!check_stripe_cache(mddev))
6571                 return -ENOSPC;
6572
6573         if (has_failed(conf))
6574                 return -EINVAL;
6575
6576         rdev_for_each(rdev, mddev) {
6577                 if (!test_bit(In_sync, &rdev->flags)
6578                     && !test_bit(Faulty, &rdev->flags))
6579                         spares++;
6580         }
6581
6582         if (spares - mddev->degraded < mddev->delta_disks - conf->max_degraded)
6583                 /* Not enough devices even to make a degraded array
6584                  * of that size
6585                  */
6586                 return -EINVAL;
6587
6588         /* Refuse to reduce size of the array.  Any reductions in
6589          * array size must be through explicit setting of array_size
6590          * attribute.
6591          */
6592         if (raid5_size(mddev, 0, conf->raid_disks + mddev->delta_disks)
6593             < mddev->array_sectors) {
6594                 printk(KERN_ERR "md/raid:%s: array size must be reduced "
6595                        "before number of disks\n", mdname(mddev));
6596                 return -EINVAL;
6597         }
6598
6599         atomic_set(&conf->reshape_stripes, 0);
6600         spin_lock_irq(&conf->device_lock);
6601         write_seqcount_begin(&conf->gen_lock);
6602         conf->previous_raid_disks = conf->raid_disks;
6603         conf->raid_disks += mddev->delta_disks;
6604         conf->prev_chunk_sectors = conf->chunk_sectors;
6605         conf->chunk_sectors = mddev->new_chunk_sectors;
6606         conf->prev_algo = conf->algorithm;
6607         conf->algorithm = mddev->new_layout;
6608         conf->generation++;
6609         /* Code that selects data_offset needs to see the generation update
6610          * if reshape_progress has been set - so a memory barrier needed.
6611          */
6612         smp_mb();
6613         if (mddev->reshape_backwards)
6614                 conf->reshape_progress = raid5_size(mddev, 0, 0);
6615         else
6616                 conf->reshape_progress = 0;
6617         conf->reshape_safe = conf->reshape_progress;
6618         write_seqcount_end(&conf->gen_lock);
6619         spin_unlock_irq(&conf->device_lock);
6620
6621         /* Now make sure any requests that proceeded on the assumption
6622          * the reshape wasn't running - like Discard or Read - have
6623          * completed.
6624          */
6625         mddev_suspend(mddev);
6626         mddev_resume(mddev);
6627
6628         /* Add some new drives, as many as will fit.
6629          * We know there are enough to make the newly sized array work.
6630          * Don't add devices if we are reducing the number of
6631          * devices in the array.  This is because it is not possible
6632          * to correctly record the "partially reconstructed" state of
6633          * such devices during the reshape and confusion could result.
6634          */
6635         if (mddev->delta_disks >= 0) {
6636                 rdev_for_each(rdev, mddev)
6637                         if (rdev->raid_disk < 0 &&
6638                             !test_bit(Faulty, &rdev->flags)) {
6639                                 if (raid5_add_disk(mddev, rdev) == 0) {
6640                                         if (rdev->raid_disk
6641                                             >= conf->previous_raid_disks)
6642                                                 set_bit(In_sync, &rdev->flags);
6643                                         else
6644                                                 rdev->recovery_offset = 0;
6645
6646                                         if (sysfs_link_rdev(mddev, rdev))
6647                                                 /* Failure here is OK */;
6648                                 }
6649                         } else if (rdev->raid_disk >= conf->previous_raid_disks
6650                                    && !test_bit(Faulty, &rdev->flags)) {
6651                                 /* This is a spare that was manually added */
6652                                 set_bit(In_sync, &rdev->flags);
6653                         }
6654
6655                 /* When a reshape changes the number of devices,
6656                  * ->degraded is measured against the larger of the
6657                  * pre and post number of devices.
6658                  */
6659                 spin_lock_irqsave(&conf->device_lock, flags);
6660                 mddev->degraded = calc_degraded(conf);
6661                 spin_unlock_irqrestore(&conf->device_lock, flags);
6662         }
6663         mddev->raid_disks = conf->raid_disks;
6664         mddev->reshape_position = conf->reshape_progress;
6665         set_bit(MD_CHANGE_DEVS, &mddev->flags);
6666
6667         clear_bit(MD_RECOVERY_SYNC, &mddev->recovery);
6668         clear_bit(MD_RECOVERY_CHECK, &mddev->recovery);
6669         set_bit(MD_RECOVERY_RESHAPE, &mddev->recovery);
6670         set_bit(MD_RECOVERY_RUNNING, &mddev->recovery);
6671         mddev->sync_thread = md_register_thread(md_do_sync, mddev,
6672                                                 "reshape");
6673         if (!mddev->sync_thread) {
6674                 mddev->recovery = 0;
6675                 spin_lock_irq(&conf->device_lock);
6676                 write_seqcount_begin(&conf->gen_lock);
6677                 mddev->raid_disks = conf->raid_disks = conf->previous_raid_disks;
6678                 mddev->new_chunk_sectors =
6679                         conf->chunk_sectors = conf->prev_chunk_sectors;
6680                 mddev->new_layout = conf->algorithm = conf->prev_algo;
6681                 rdev_for_each(rdev, mddev)
6682                         rdev->new_data_offset = rdev->data_offset;
6683                 smp_wmb();
6684                 conf->generation --;
6685                 conf->reshape_progress = MaxSector;
6686                 mddev->reshape_position = MaxSector;
6687                 write_seqcount_end(&conf->gen_lock);
6688                 spin_unlock_irq(&conf->device_lock);
6689                 return -EAGAIN;
6690         }
6691         conf->reshape_checkpoint = jiffies;
6692         md_wakeup_thread(mddev->sync_thread);
6693         md_new_event(mddev);
6694         return 0;
6695 }
6696
6697 /* This is called from the reshape thread and should make any
6698  * changes needed in 'conf'
6699  */
6700 static void end_reshape(struct r5conf *conf)
6701 {
6702
6703         if (!test_bit(MD_RECOVERY_INTR, &conf->mddev->recovery)) {
6704                 struct md_rdev *rdev;
6705
6706                 spin_lock_irq(&conf->device_lock);
6707                 conf->previous_raid_disks = conf->raid_disks;
6708                 rdev_for_each(rdev, conf->mddev)
6709                         rdev->data_offset = rdev->new_data_offset;
6710                 smp_wmb();
6711                 conf->reshape_progress = MaxSector;
6712                 spin_unlock_irq(&conf->device_lock);
6713                 wake_up(&conf->wait_for_overlap);
6714
6715                 /* read-ahead size must cover two whole stripes, which is
6716                  * 2 * (datadisks) * chunksize where 'n' is the number of raid devices
6717                  */
6718                 if (conf->mddev->queue) {
6719                         int data_disks = conf->raid_disks - conf->max_degraded;
6720                         int stripe = data_disks * ((conf->chunk_sectors << 9)
6721                                                    / PAGE_SIZE);
6722                         if (conf->mddev->queue->backing_dev_info.ra_pages < 2 * stripe)
6723                                 conf->mddev->queue->backing_dev_info.ra_pages = 2 * stripe;
6724                 }
6725         }
6726 }
6727
6728 /* This is called from the raid5d thread with mddev_lock held.
6729  * It makes config changes to the device.
6730  */
6731 static void raid5_finish_reshape(struct mddev *mddev)
6732 {
6733         struct r5conf *conf = mddev->private;
6734
6735         if (!test_bit(MD_RECOVERY_INTR, &mddev->recovery)) {
6736
6737                 if (mddev->delta_disks > 0) {
6738                         md_set_array_sectors(mddev, raid5_size(mddev, 0, 0));
6739                         set_capacity(mddev->gendisk, mddev->array_sectors);
6740                         revalidate_disk(mddev->gendisk);
6741                 } else {
6742                         int d;
6743                         spin_lock_irq(&conf->device_lock);
6744                         mddev->degraded = calc_degraded(conf);
6745                         spin_unlock_irq(&conf->device_lock);
6746                         for (d = conf->raid_disks ;
6747                              d < conf->raid_disks - mddev->delta_disks;
6748                              d++) {
6749                                 struct md_rdev *rdev = conf->disks[d].rdev;
6750                                 if (rdev)
6751                                         clear_bit(In_sync, &rdev->flags);
6752                                 rdev = conf->disks[d].replacement;
6753                                 if (rdev)
6754                                         clear_bit(In_sync, &rdev->flags);
6755                         }
6756                 }
6757                 mddev->layout = conf->algorithm;
6758                 mddev->chunk_sectors = conf->chunk_sectors;
6759                 mddev->reshape_position = MaxSector;
6760                 mddev->delta_disks = 0;
6761                 mddev->reshape_backwards = 0;
6762         }
6763 }
6764
6765 static void raid5_quiesce(struct mddev *mddev, int state)
6766 {
6767         struct r5conf *conf = mddev->private;
6768
6769         switch(state) {
6770         case 2: /* resume for a suspend */
6771                 wake_up(&conf->wait_for_overlap);
6772                 break;
6773
6774         case 1: /* stop all writes */
6775                 lock_all_device_hash_locks_irq(conf);
6776                 /* '2' tells resync/reshape to pause so that all
6777                  * active stripes can drain
6778                  */
6779                 conf->quiesce = 2;
6780                 wait_event_cmd(conf->wait_for_stripe,
6781                                     atomic_read(&conf->active_stripes) == 0 &&
6782                                     atomic_read(&conf->active_aligned_reads) == 0,
6783                                     unlock_all_device_hash_locks_irq(conf),
6784                                     lock_all_device_hash_locks_irq(conf));
6785                 conf->quiesce = 1;
6786                 unlock_all_device_hash_locks_irq(conf);
6787                 /* allow reshape to continue */
6788                 wake_up(&conf->wait_for_overlap);
6789                 break;
6790
6791         case 0: /* re-enable writes */
6792                 lock_all_device_hash_locks_irq(conf);
6793                 conf->quiesce = 0;
6794                 wake_up(&conf->wait_for_stripe);
6795                 wake_up(&conf->wait_for_overlap);
6796                 unlock_all_device_hash_locks_irq(conf);
6797                 break;
6798         }
6799 }
6800
6801 static void *raid45_takeover_raid0(struct mddev *mddev, int level)
6802 {
6803         struct r0conf *raid0_conf = mddev->private;
6804         sector_t sectors;
6805
6806         /* for raid0 takeover only one zone is supported */
6807         if (raid0_conf->nr_strip_zones > 1) {
6808                 printk(KERN_ERR "md/raid:%s: cannot takeover raid0 with more than one zone.\n",
6809                        mdname(mddev));
6810                 return ERR_PTR(-EINVAL);
6811         }
6812
6813         sectors = raid0_conf->strip_zone[0].zone_end;
6814         sector_div(sectors, raid0_conf->strip_zone[0].nb_dev);
6815         mddev->dev_sectors = sectors;
6816         mddev->new_level = level;
6817         mddev->new_layout = ALGORITHM_PARITY_N;
6818         mddev->new_chunk_sectors = mddev->chunk_sectors;
6819         mddev->raid_disks += 1;
6820         mddev->delta_disks = 1;
6821         /* make sure it will be not marked as dirty */
6822         mddev->recovery_cp = MaxSector;
6823
6824         return setup_conf(mddev);
6825 }
6826
6827 static void *raid5_takeover_raid1(struct mddev *mddev)
6828 {
6829         int chunksect;
6830
6831         if (mddev->raid_disks != 2 ||
6832             mddev->degraded > 1)
6833                 return ERR_PTR(-EINVAL);
6834
6835         /* Should check if there are write-behind devices? */
6836
6837         chunksect = 64*2; /* 64K by default */
6838
6839         /* The array must be an exact multiple of chunksize */
6840         while (chunksect && (mddev->array_sectors & (chunksect-1)))
6841                 chunksect >>= 1;
6842
6843         if ((chunksect<<9) < STRIPE_SIZE)
6844                 /* array size does not allow a suitable chunk size */
6845                 return ERR_PTR(-EINVAL);
6846
6847         mddev->new_level = 5;
6848         mddev->new_layout = ALGORITHM_LEFT_SYMMETRIC;
6849         mddev->new_chunk_sectors = chunksect;
6850
6851         return setup_conf(mddev);
6852 }
6853
6854 static void *raid5_takeover_raid6(struct mddev *mddev)
6855 {
6856         int new_layout;
6857
6858         switch (mddev->layout) {
6859         case ALGORITHM_LEFT_ASYMMETRIC_6:
6860                 new_layout = ALGORITHM_LEFT_ASYMMETRIC;
6861                 break;
6862         case ALGORITHM_RIGHT_ASYMMETRIC_6:
6863                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC;
6864                 break;
6865         case ALGORITHM_LEFT_SYMMETRIC_6:
6866                 new_layout = ALGORITHM_LEFT_SYMMETRIC;
6867                 break;
6868         case ALGORITHM_RIGHT_SYMMETRIC_6:
6869                 new_layout = ALGORITHM_RIGHT_SYMMETRIC;
6870                 break;
6871         case ALGORITHM_PARITY_0_6:
6872                 new_layout = ALGORITHM_PARITY_0;
6873                 break;
6874         case ALGORITHM_PARITY_N:
6875                 new_layout = ALGORITHM_PARITY_N;
6876                 break;
6877         default:
6878                 return ERR_PTR(-EINVAL);
6879         }
6880         mddev->new_level = 5;
6881         mddev->new_layout = new_layout;
6882         mddev->delta_disks = -1;
6883         mddev->raid_disks -= 1;
6884         return setup_conf(mddev);
6885 }
6886
6887 static int raid5_check_reshape(struct mddev *mddev)
6888 {
6889         /* For a 2-drive array, the layout and chunk size can be changed
6890          * immediately as not restriping is needed.
6891          * For larger arrays we record the new value - after validation
6892          * to be used by a reshape pass.
6893          */
6894         struct r5conf *conf = mddev->private;
6895         int new_chunk = mddev->new_chunk_sectors;
6896
6897         if (mddev->new_layout >= 0 && !algorithm_valid_raid5(mddev->new_layout))
6898                 return -EINVAL;
6899         if (new_chunk > 0) {
6900                 if (!is_power_of_2(new_chunk))
6901                         return -EINVAL;
6902                 if (new_chunk < (PAGE_SIZE>>9))
6903                         return -EINVAL;
6904                 if (mddev->array_sectors & (new_chunk-1))
6905                         /* not factor of array size */
6906                         return -EINVAL;
6907         }
6908
6909         /* They look valid */
6910
6911         if (mddev->raid_disks == 2) {
6912                 /* can make the change immediately */
6913                 if (mddev->new_layout >= 0) {
6914                         conf->algorithm = mddev->new_layout;
6915                         mddev->layout = mddev->new_layout;
6916                 }
6917                 if (new_chunk > 0) {
6918                         conf->chunk_sectors = new_chunk ;
6919                         mddev->chunk_sectors = new_chunk;
6920                 }
6921                 set_bit(MD_CHANGE_DEVS, &mddev->flags);
6922                 md_wakeup_thread(mddev->thread);
6923         }
6924         return check_reshape(mddev);
6925 }
6926
6927 static int raid6_check_reshape(struct mddev *mddev)
6928 {
6929         int new_chunk = mddev->new_chunk_sectors;
6930
6931         if (mddev->new_layout >= 0 && !algorithm_valid_raid6(mddev->new_layout))
6932                 return -EINVAL;
6933         if (new_chunk > 0) {
6934                 if (!is_power_of_2(new_chunk))
6935                         return -EINVAL;
6936                 if (new_chunk < (PAGE_SIZE >> 9))
6937                         return -EINVAL;
6938                 if (mddev->array_sectors & (new_chunk-1))
6939                         /* not factor of array size */
6940                         return -EINVAL;
6941         }
6942
6943         /* They look valid */
6944         return check_reshape(mddev);
6945 }
6946
6947 static void *raid5_takeover(struct mddev *mddev)
6948 {
6949         /* raid5 can take over:
6950          *  raid0 - if there is only one strip zone - make it a raid4 layout
6951          *  raid1 - if there are two drives.  We need to know the chunk size
6952          *  raid4 - trivial - just use a raid4 layout.
6953          *  raid6 - Providing it is a *_6 layout
6954          */
6955         if (mddev->level == 0)
6956                 return raid45_takeover_raid0(mddev, 5);
6957         if (mddev->level == 1)
6958                 return raid5_takeover_raid1(mddev);
6959         if (mddev->level == 4) {
6960                 mddev->new_layout = ALGORITHM_PARITY_N;
6961                 mddev->new_level = 5;
6962                 return setup_conf(mddev);
6963         }
6964         if (mddev->level == 6)
6965                 return raid5_takeover_raid6(mddev);
6966
6967         return ERR_PTR(-EINVAL);
6968 }
6969
6970 static void *raid4_takeover(struct mddev *mddev)
6971 {
6972         /* raid4 can take over:
6973          *  raid0 - if there is only one strip zone
6974          *  raid5 - if layout is right
6975          */
6976         if (mddev->level == 0)
6977                 return raid45_takeover_raid0(mddev, 4);
6978         if (mddev->level == 5 &&
6979             mddev->layout == ALGORITHM_PARITY_N) {
6980                 mddev->new_layout = 0;
6981                 mddev->new_level = 4;
6982                 return setup_conf(mddev);
6983         }
6984         return ERR_PTR(-EINVAL);
6985 }
6986
6987 static struct md_personality raid5_personality;
6988
6989 static void *raid6_takeover(struct mddev *mddev)
6990 {
6991         /* Currently can only take over a raid5.  We map the
6992          * personality to an equivalent raid6 personality
6993          * with the Q block at the end.
6994          */
6995         int new_layout;
6996
6997         if (mddev->pers != &raid5_personality)
6998                 return ERR_PTR(-EINVAL);
6999         if (mddev->degraded > 1)
7000                 return ERR_PTR(-EINVAL);
7001         if (mddev->raid_disks > 253)
7002                 return ERR_PTR(-EINVAL);
7003         if (mddev->raid_disks < 3)
7004                 return ERR_PTR(-EINVAL);
7005
7006         switch (mddev->layout) {
7007         case ALGORITHM_LEFT_ASYMMETRIC:
7008                 new_layout = ALGORITHM_LEFT_ASYMMETRIC_6;
7009                 break;
7010         case ALGORITHM_RIGHT_ASYMMETRIC:
7011                 new_layout = ALGORITHM_RIGHT_ASYMMETRIC_6;
7012                 break;
7013         case ALGORITHM_LEFT_SYMMETRIC:
7014                 new_layout = ALGORITHM_LEFT_SYMMETRIC_6;
7015                 break;
7016         case ALGORITHM_RIGHT_SYMMETRIC:
7017                 new_layout = ALGORITHM_RIGHT_SYMMETRIC_6;
7018                 break;
7019         case ALGORITHM_PARITY_0:
7020                 new_layout = ALGORITHM_PARITY_0_6;
7021                 break;
7022         case ALGORITHM_PARITY_N:
7023                 new_layout = ALGORITHM_PARITY_N;
7024                 break;
7025         default:
7026                 return ERR_PTR(-EINVAL);
7027         }
7028         mddev->new_level = 6;
7029         mddev->new_layout = new_layout;
7030         mddev->delta_disks = 1;
7031         mddev->raid_disks += 1;
7032         return setup_conf(mddev);
7033 }
7034
7035 static struct md_personality raid6_personality =
7036 {
7037         .name           = "raid6",
7038         .level          = 6,
7039         .owner          = THIS_MODULE,
7040         .make_request   = make_request,
7041         .run            = run,
7042         .stop           = stop,
7043         .status         = status,
7044         .error_handler  = error,
7045         .hot_add_disk   = raid5_add_disk,
7046         .hot_remove_disk= raid5_remove_disk,
7047         .spare_active   = raid5_spare_active,
7048         .sync_request   = sync_request,
7049         .resize         = raid5_resize,
7050         .size           = raid5_size,
7051         .check_reshape  = raid6_check_reshape,
7052         .start_reshape  = raid5_start_reshape,
7053         .finish_reshape = raid5_finish_reshape,
7054         .quiesce        = raid5_quiesce,
7055         .takeover       = raid6_takeover,
7056 };
7057 static struct md_personality raid5_personality =
7058 {
7059         .name           = "raid5",
7060         .level          = 5,
7061         .owner          = THIS_MODULE,
7062         .make_request   = make_request,
7063         .run            = run,
7064         .stop           = stop,
7065         .status         = status,
7066         .error_handler  = error,
7067         .hot_add_disk   = raid5_add_disk,
7068         .hot_remove_disk= raid5_remove_disk,
7069         .spare_active   = raid5_spare_active,
7070         .sync_request   = sync_request,
7071         .resize         = raid5_resize,
7072         .size           = raid5_size,
7073         .check_reshape  = raid5_check_reshape,
7074         .start_reshape  = raid5_start_reshape,
7075         .finish_reshape = raid5_finish_reshape,
7076         .quiesce        = raid5_quiesce,
7077         .takeover       = raid5_takeover,
7078 };
7079
7080 static struct md_personality raid4_personality =
7081 {
7082         .name           = "raid4",
7083         .level          = 4,
7084         .owner          = THIS_MODULE,
7085         .make_request   = make_request,
7086         .run            = run,
7087         .stop           = stop,
7088         .status         = status,
7089         .error_handler  = error,
7090         .hot_add_disk   = raid5_add_disk,
7091         .hot_remove_disk= raid5_remove_disk,
7092         .spare_active   = raid5_spare_active,
7093         .sync_request   = sync_request,
7094         .resize         = raid5_resize,
7095         .size           = raid5_size,
7096         .check_reshape  = raid5_check_reshape,
7097         .start_reshape  = raid5_start_reshape,
7098         .finish_reshape = raid5_finish_reshape,
7099         .quiesce        = raid5_quiesce,
7100         .takeover       = raid4_takeover,
7101 };
7102
7103 static int __init raid5_init(void)
7104 {
7105         raid5_wq = alloc_workqueue("raid5wq",
7106                 WQ_UNBOUND|WQ_MEM_RECLAIM|WQ_CPU_INTENSIVE|WQ_SYSFS, 0);
7107         if (!raid5_wq)
7108                 return -ENOMEM;
7109         register_md_personality(&raid6_personality);
7110         register_md_personality(&raid5_personality);
7111         register_md_personality(&raid4_personality);
7112         return 0;
7113 }
7114
7115 static void raid5_exit(void)
7116 {
7117         unregister_md_personality(&raid6_personality);
7118         unregister_md_personality(&raid5_personality);
7119         unregister_md_personality(&raid4_personality);
7120         destroy_workqueue(raid5_wq);
7121 }
7122
7123 module_init(raid5_init);
7124 module_exit(raid5_exit);
7125 MODULE_LICENSE("GPL");
7126 MODULE_DESCRIPTION("RAID4/5/6 (striping with parity) personality for MD");
7127 MODULE_ALIAS("md-personality-4"); /* RAID5 */
7128 MODULE_ALIAS("md-raid5");
7129 MODULE_ALIAS("md-raid4");
7130 MODULE_ALIAS("md-level-5");
7131 MODULE_ALIAS("md-level-4");
7132 MODULE_ALIAS("md-personality-8"); /* RAID6 */
7133 MODULE_ALIAS("md-raid6");
7134 MODULE_ALIAS("md-level-6");
7135
7136 /* This used to be two separate modules, they were: */
7137 MODULE_ALIAS("raid5");
7138 MODULE_ALIAS("raid6");