fs/gfs2/glock.c

   1 /*
   2  * Copyright (C) Sistina Software, Inc.  1997-2003 All rights reserved.
   3  * Copyright (C) 2004-2008 Red Hat, Inc.  All rights reserved.
   4  *
   5  * This copyrighted material is made available to anyone wishing to use,
   6  * modify, copy, or redistribute it subject to the terms and conditions
   7  * of the GNU General Public License version 2.
   8  */
   9
  10 #include <linux/sched.h>
  11 #include <linux/slab.h>
  12 #include <linux/spinlock.h>
  13 #include <linux/buffer_head.h>
  14 #include <linux/delay.h>
  15 #include <linux/sort.h>
  16 #include <linux/jhash.h>
  17 #include <linux/kallsyms.h>
  18 #include <linux/gfs2_ondisk.h>
  19 #include <linux/list.h>
  20 #include <linux/wait.h>
  21 #include <linux/module.h>
  22 #include <asm/uaccess.h>
  23 #include <linux/seq_file.h>
  24 #include <linux/debugfs.h>
  25 #include <linux/kthread.h>
  26 #include <linux/freezer.h>
  27 #include <linux/workqueue.h>
  28 #include <linux/jiffies.h>
  29 #include <linux/rcupdate.h>
  30 #include <linux/rculist_bl.h>
  31 #include <linux/bit_spinlock.h>
  32 #include <linux/percpu.h>
  33 #include <linux/list_sort.h>
  34 #include <linux/lockref.h>
  35
  36 #include "gfs2.h"
  37 #include "incore.h"
  38 #include "glock.h"
  39 #include "glops.h"
  40 #include "inode.h"
  41 #include "lops.h"
  42 #include "meta_io.h"
  43 #include "quota.h"
  44 #include "super.h"
  45 #include "util.h"
  46 #include "bmap.h"
  47 #define CREATE_TRACE_POINTS
  48 #include "trace_gfs2.h"
  49
  50 struct gfs2_glock_iter {
  51         int hash;                       /* hash bucket index           */
  52         unsigned nhash;                 /* Index within current bucket */
  53         struct gfs2_sbd *sdp;           /* incore superblock           */
  54         struct gfs2_glock *gl;          /* current glock struct        */
  55         loff_t last_pos;                /* last position               */
  56 };
  57
  58 typedef void (*glock_examiner) (struct gfs2_glock * gl);
  59
  60 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target);
  61
  62 static struct dentry *gfs2_root;
  63 static struct workqueue_struct *glock_workqueue;
  64 struct workqueue_struct *gfs2_delete_workqueue;
  65 static LIST_HEAD(lru_list);
  66 static atomic_t lru_count = ATOMIC_INIT(0);
  67 static DEFINE_SPINLOCK(lru_lock);
  68
  69 #define GFS2_GL_HASH_SHIFT      15
  70 #define GFS2_GL_HASH_SIZE       (1 << GFS2_GL_HASH_SHIFT)
  71 #define GFS2_GL_HASH_MASK       (GFS2_GL_HASH_SIZE - 1)
  72
  73 static struct hlist_bl_head gl_hash_table[GFS2_GL_HASH_SIZE];
  74 static struct dentry *gfs2_root;
  75
  76 /**
  77  * gl_hash() - Turn glock number into hash bucket number
  78  * @lock: The glock number
  79  *
  80  * Returns: The number of the corresponding hash bucket
  81  */
  82
  83 static unsigned int gl_hash(const struct gfs2_sbd *sdp,
  84                             const struct lm_lockname *name)
  85 {
  86         unsigned int h;
  87
  88         h = jhash(&name->ln_number, sizeof(u64), 0);
  89         h = jhash(&name->ln_type, sizeof(unsigned int), h);
  90         h = jhash(&sdp, sizeof(struct gfs2_sbd *), h);
  91         h &= GFS2_GL_HASH_MASK;
  92
  93         return h;
  94 }
  95
  96 static inline void spin_lock_bucket(unsigned int hash)
  97 {
  98         hlist_bl_lock(&gl_hash_table[hash]);
  99 }
 100
 101 static inline void spin_unlock_bucket(unsigned int hash)
 102 {
 103         hlist_bl_unlock(&gl_hash_table[hash]);
 104 }
 105
 106 static void gfs2_glock_dealloc(struct rcu_head *rcu)
 107 {
 108         struct gfs2_glock *gl = container_of(rcu, struct gfs2_glock, gl_rcu);
 109
 110         if (gl->gl_ops->go_flags & GLOF_ASPACE) {
 111                 kmem_cache_free(gfs2_glock_aspace_cachep, gl);
 112         } else {
 113                 kfree(gl->gl_lksb.sb_lvbptr);
 114                 kmem_cache_free(gfs2_glock_cachep, gl);
 115         }
 116 }
 117
 118 void gfs2_glock_free(struct gfs2_glock *gl)
 119 {
 120         struct gfs2_sbd *sdp = gl->gl_sbd;
 121
 122         call_rcu(&gl->gl_rcu, gfs2_glock_dealloc);
 123         if (atomic_dec_and_test(&sdp->sd_glock_disposal))
 124                 wake_up(&sdp->sd_glock_wait);
 125 }
 126
 127 /**
 128  * gfs2_glock_hold() - increment reference count on glock
 129  * @gl: The glock to hold
 130  *
 131  */
 132
 133 static void gfs2_glock_hold(struct gfs2_glock *gl)
 134 {
 135         GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
 136         lockref_get(&gl->gl_lockref);
 137 }
 138
 139 /**
 140  * demote_ok - Check to see if it's ok to unlock a glock
 141  * @gl: the glock
 142  *
 143  * Returns: 1 if it's ok
 144  */
 145
 146 static int demote_ok(const struct gfs2_glock *gl)
 147 {
 148         const struct gfs2_glock_operations *glops = gl->gl_ops;
 149
 150         if (gl->gl_state == LM_ST_UNLOCKED)
 151                 return 0;
 152         if (!list_empty(&gl->gl_holders))
 153                 return 0;
 154         if (glops->go_demote_ok)
 155                 return glops->go_demote_ok(gl);
 156         return 1;
 157 }
 158
 159
 160 void gfs2_glock_add_to_lru(struct gfs2_glock *gl)
 161 {
 162         spin_lock(&lru_lock);
 163
 164         if (!list_empty(&gl->gl_lru))
 165                 list_del_init(&gl->gl_lru);
 166         else
 167                 atomic_inc(&lru_count);
 168
 169         list_add_tail(&gl->gl_lru, &lru_list);
 170         set_bit(GLF_LRU, &gl->gl_flags);
 171         spin_unlock(&lru_lock);
 172 }
 173
 174 static void __gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
 175 {
 176         if (!list_empty(&gl->gl_lru)) {
 177                 list_del_init(&gl->gl_lru);
 178                 atomic_dec(&lru_count);
 179                 clear_bit(GLF_LRU, &gl->gl_flags);
 180         }
 181 }
 182
 183 static void gfs2_glock_remove_from_lru(struct gfs2_glock *gl)
 184 {
 185         spin_lock(&lru_lock);
 186         __gfs2_glock_remove_from_lru(gl);
 187         spin_unlock(&lru_lock);
 188 }
 189
 190 /**
 191  * gfs2_glock_put() - Decrement reference count on glock
 192  * @gl: The glock to put
 193  *
 194  */
 195
 196 void gfs2_glock_put(struct gfs2_glock *gl)
 197 {
 198         struct gfs2_sbd *sdp = gl->gl_sbd;
 199         struct address_space *mapping = gfs2_glock2aspace(gl);
 200
 201         if (lockref_put_or_lock(&gl->gl_lockref))
 202                 return;
 203
 204         lockref_mark_dead(&gl->gl_lockref);
 205
 206         spin_lock(&lru_lock);
 207         __gfs2_glock_remove_from_lru(gl);
 208         spin_unlock(&lru_lock);
 209         spin_unlock(&gl->gl_lockref.lock);
 210         spin_lock_bucket(gl->gl_hash);
 211         hlist_bl_del_rcu(&gl->gl_list);
 212         spin_unlock_bucket(gl->gl_hash);
 213         GLOCK_BUG_ON(gl, !list_empty(&gl->gl_holders));
 214         GLOCK_BUG_ON(gl, mapping && mapping->nrpages);
 215         trace_gfs2_glock_put(gl);
 216         sdp->sd_lockstruct.ls_ops->lm_put_lock(gl);
 217 }
 218
 219 /**
 220  * search_bucket() - Find struct gfs2_glock by lock number
 221  * @bucket: the bucket to search
 222  * @name: The lock name
 223  *
 224  * Returns: NULL, or the struct gfs2_glock with the requested number
 225  */
 226
 227 static struct gfs2_glock *search_bucket(unsigned int hash,
 228                                         const struct gfs2_sbd *sdp,
 229                                         const struct lm_lockname *name)
 230 {
 231         struct gfs2_glock *gl;
 232         struct hlist_bl_node *h;
 233
 234         hlist_bl_for_each_entry_rcu(gl, h, &gl_hash_table[hash], gl_list) {
 235                 if (!lm_name_equal(&gl->gl_name, name))
 236                         continue;
 237                 if (gl->gl_sbd != sdp)
 238                         continue;
 239                 if (lockref_get_not_dead(&gl->gl_lockref))
 240                         return gl;
 241         }
 242
 243         return NULL;
 244 }
 245
 246 /**
 247  * may_grant - check if its ok to grant a new lock
 248  * @gl: The glock
 249  * @gh: The lock request which we wish to grant
 250  *
 251  * Returns: true if its ok to grant the lock
 252  */
 253
 254 static inline int may_grant(const struct gfs2_glock *gl, const struct gfs2_holder *gh)
 255 {
 256         const struct gfs2_holder *gh_head = list_entry(gl->gl_holders.next, const struct gfs2_holder, gh_list);
 257         if ((gh->gh_state == LM_ST_EXCLUSIVE ||
 258              gh_head->gh_state == LM_ST_EXCLUSIVE) && gh != gh_head)
 259                 return 0;
 260         if (gl->gl_state == gh->gh_state)
 261                 return 1;
 262         if (gh->gh_flags & GL_EXACT)
 263                 return 0;
 264         if (gl->gl_state == LM_ST_EXCLUSIVE) {
 265                 if (gh->gh_state == LM_ST_SHARED && gh_head->gh_state == LM_ST_SHARED)
 266                         return 1;
 267                 if (gh->gh_state == LM_ST_DEFERRED && gh_head->gh_state == LM_ST_DEFERRED)
 268                         return 1;
 269         }
 270         if (gl->gl_state != LM_ST_UNLOCKED && (gh->gh_flags & LM_FLAG_ANY))
 271                 return 1;
 272         return 0;
 273 }
 274
 275 static void gfs2_holder_wake(struct gfs2_holder *gh)
 276 {
 277         clear_bit(HIF_WAIT, &gh->gh_iflags);
 278         smp_mb__after_clear_bit();
 279         wake_up_bit(&gh->gh_iflags, HIF_WAIT);
 280 }
 281
 282 /**
 283  * do_error - Something unexpected has happened during a lock request
 284  *
 285  */
 286
 287 static inline void do_error(struct gfs2_glock *gl, const int ret)
 288 {
 289         struct gfs2_holder *gh, *tmp;
 290
 291         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 292                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 293                         continue;
 294                 if (ret & LM_OUT_ERROR)
 295                         gh->gh_error = -EIO;
 296                 else if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))
 297                         gh->gh_error = GLR_TRYFAILED;
 298                 else
 299                         continue;
 300                 list_del_init(&gh->gh_list);
 301                 trace_gfs2_glock_queue(gh, 0);
 302                 gfs2_holder_wake(gh);
 303         }
 304 }
 305
 306 /**
 307  * do_promote - promote as many requests as possible on the current queue
 308  * @gl: The glock
 309  *
 310  * Returns: 1 if there is a blocked holder at the head of the list, or 2
 311  *          if a type specific operation is underway.
 312  */
 313
 314 static int do_promote(struct gfs2_glock *gl)
 315 __releases(&gl->gl_spin)
 316 __acquires(&gl->gl_spin)
 317 {
 318         const struct gfs2_glock_operations *glops = gl->gl_ops;
 319         struct gfs2_holder *gh, *tmp;
 320         int ret;
 321
 322 restart:
 323         list_for_each_entry_safe(gh, tmp, &gl->gl_holders, gh_list) {
 324                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 325                         continue;
 326                 if (may_grant(gl, gh)) {
 327                         if (gh->gh_list.prev == &gl->gl_holders &&
 328                             glops->go_lock) {
 329                                 spin_unlock(&gl->gl_spin);
 330                                 /* FIXME: eliminate this eventually */
 331                                 ret = glops->go_lock(gh);
 332                                 spin_lock(&gl->gl_spin);
 333                                 if (ret) {
 334                                         if (ret == 1)
 335                                                 return 2;
 336                                         gh->gh_error = ret;
 337                                         list_del_init(&gh->gh_list);
 338                                         trace_gfs2_glock_queue(gh, 0);
 339                                         gfs2_holder_wake(gh);
 340                                         goto restart;
 341                                 }
 342                                 set_bit(HIF_HOLDER, &gh->gh_iflags);
 343                                 trace_gfs2_promote(gh, 1);
 344                                 gfs2_holder_wake(gh);
 345                                 goto restart;
 346                         }
 347                         set_bit(HIF_HOLDER, &gh->gh_iflags);
 348                         trace_gfs2_promote(gh, 0);
 349                         gfs2_holder_wake(gh);
 350                         continue;
 351                 }
 352                 if (gh->gh_list.prev == &gl->gl_holders)
 353                         return 1;
 354                 do_error(gl, 0);
 355                 break;
 356         }
 357         return 0;
 358 }
 359
 360 /**
 361  * find_first_waiter - find the first gh that's waiting for the glock
 362  * @gl: the glock
 363  */
 364
 365 static inline struct gfs2_holder *find_first_waiter(const struct gfs2_glock *gl)
 366 {
 367         struct gfs2_holder *gh;
 368
 369         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
 370                 if (!test_bit(HIF_HOLDER, &gh->gh_iflags))
 371                         return gh;
 372         }
 373         return NULL;
 374 }
 375
 376 /**
 377  * state_change - record that the glock is now in a different state
 378  * @gl: the glock
 379  * @new_state the new state
 380  *
 381  */
 382
 383 static void state_change(struct gfs2_glock *gl, unsigned int new_state)
 384 {
 385         int held1, held2;
 386
 387         held1 = (gl->gl_state != LM_ST_UNLOCKED);
 388         held2 = (new_state != LM_ST_UNLOCKED);
 389
 390         if (held1 != held2) {
 391                 GLOCK_BUG_ON(gl, __lockref_is_dead(&gl->gl_lockref));
 392                 if (held2)
 393                         gl->gl_lockref.count++;
 394                 else
 395                         gl->gl_lockref.count--;
 396         }
 397         if (held1 && held2 && list_empty(&gl->gl_holders))
 398                 clear_bit(GLF_QUEUED, &gl->gl_flags);
 399
 400         if (new_state != gl->gl_target)
 401                 /* shorten our minimum hold time */
 402                 gl->gl_hold_time = max(gl->gl_hold_time - GL_GLOCK_HOLD_DECR,
 403                                        GL_GLOCK_MIN_HOLD);
 404         gl->gl_state = new_state;
 405         gl->gl_tchange = jiffies;
 406 }
 407
 408 static void gfs2_demote_wake(struct gfs2_glock *gl)
 409 {
 410         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 411         clear_bit(GLF_DEMOTE, &gl->gl_flags);
 412         smp_mb__after_clear_bit();
 413         wake_up_bit(&gl->gl_flags, GLF_DEMOTE);
 414 }
 415
 416 /**
 417  * finish_xmote - The DLM has replied to one of our lock requests
 418  * @gl: The glock
 419  * @ret: The status from the DLM
 420  *
 421  */
 422
 423 static void finish_xmote(struct gfs2_glock *gl, unsigned int ret)
 424 {
 425         const struct gfs2_glock_operations *glops = gl->gl_ops;
 426         struct gfs2_holder *gh;
 427         unsigned state = ret & LM_OUT_ST_MASK;
 428         int rv;
 429
 430         spin_lock(&gl->gl_spin);
 431         trace_gfs2_glock_state_change(gl, state);
 432         state_change(gl, state);
 433         gh = find_first_waiter(gl);
 434
 435         /* Demote to UN request arrived during demote to SH or DF */
 436         if (test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags) &&
 437             state != LM_ST_UNLOCKED && gl->gl_demote_state == LM_ST_UNLOCKED)
 438                 gl->gl_target = LM_ST_UNLOCKED;
 439
 440         /* Check for state != intended state */
 441         if (unlikely(state != gl->gl_target)) {
 442                 if (gh && !test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags)) {
 443                         /* move to back of queue and try next entry */
 444                         if (ret & LM_OUT_CANCELED) {
 445                                 if ((gh->gh_flags & LM_FLAG_PRIORITY) == 0)
 446                                         list_move_tail(&gh->gh_list, &gl->gl_holders);
 447                                 gh = find_first_waiter(gl);
 448                                 gl->gl_target = gh->gh_state;
 449                                 goto retry;
 450                         }
 451                         /* Some error or failed "try lock" - report it */
 452                         if ((ret & LM_OUT_ERROR) ||
 453                             (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 454                                 gl->gl_target = gl->gl_state;
 455                                 do_error(gl, ret);
 456                                 goto out;
 457                         }
 458                 }
 459                 switch(state) {
 460                 /* Unlocked due to conversion deadlock, try again */
 461                 case LM_ST_UNLOCKED:
 462 retry:
 463                         do_xmote(gl, gh, gl->gl_target);
 464                         break;
 465                 /* Conversion fails, unlock and try again */
 466                 case LM_ST_SHARED:
 467                 case LM_ST_DEFERRED:
 468                         do_xmote(gl, gh, LM_ST_UNLOCKED);
 469                         break;
 470                 default: /* Everything else */
 471                         printk(KERN_ERR "GFS2: wanted %u got %u\n", gl->gl_target, state);
 472                         GLOCK_BUG_ON(gl, 1);
 473                 }
 474                 spin_unlock(&gl->gl_spin);
 475                 return;
 476         }
 477
 478         /* Fast path - we got what we asked for */
 479         if (test_and_clear_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags))
 480                 gfs2_demote_wake(gl);
 481         if (state != LM_ST_UNLOCKED) {
 482                 if (glops->go_xmote_bh) {
 483                         spin_unlock(&gl->gl_spin);
 484                         rv = glops->go_xmote_bh(gl, gh);
 485                         spin_lock(&gl->gl_spin);
 486                         if (rv) {
 487                                 do_error(gl, rv);
 488                                 goto out;
 489                         }
 490                 }
 491                 rv = do_promote(gl);
 492                 if (rv == 2)
 493                         goto out_locked;
 494         }
 495 out:
 496         clear_bit(GLF_LOCK, &gl->gl_flags);
 497 out_locked:
 498         spin_unlock(&gl->gl_spin);
 499 }
 500
 501 /**
 502  * do_xmote - Calls the DLM to change the state of a lock
 503  * @gl: The lock state
 504  * @gh: The holder (only for promotes)
 505  * @target: The target lock state
 506  *
 507  */
 508
 509 static void do_xmote(struct gfs2_glock *gl, struct gfs2_holder *gh, unsigned int target)
 510 __releases(&gl->gl_spin)
 511 __acquires(&gl->gl_spin)
 512 {
 513         const struct gfs2_glock_operations *glops = gl->gl_ops;
 514         struct gfs2_sbd *sdp = gl->gl_sbd;
 515         unsigned int lck_flags = gh ? gh->gh_flags : 0;
 516         int ret;
 517
 518         lck_flags &= (LM_FLAG_TRY | LM_FLAG_TRY_1CB | LM_FLAG_NOEXP |
 519                       LM_FLAG_PRIORITY);
 520         GLOCK_BUG_ON(gl, gl->gl_state == target);
 521         GLOCK_BUG_ON(gl, gl->gl_state == gl->gl_target);
 522         if ((target == LM_ST_UNLOCKED || target == LM_ST_DEFERRED) &&
 523             glops->go_inval) {
 524                 set_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 525                 do_error(gl, 0); /* Fail queued try locks */
 526         }
 527         gl->gl_req = target;
 528         set_bit(GLF_BLOCKING, &gl->gl_flags);
 529         if ((gl->gl_req == LM_ST_UNLOCKED) ||
 530             (gl->gl_state == LM_ST_EXCLUSIVE) ||
 531             (lck_flags & (LM_FLAG_TRY|LM_FLAG_TRY_1CB)))
 532                 clear_bit(GLF_BLOCKING, &gl->gl_flags);
 533         spin_unlock(&gl->gl_spin);
 534         if (glops->go_sync)
 535                 glops->go_sync(gl);
 536         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 537                 glops->go_inval(gl, target == LM_ST_DEFERRED ? 0 : DIO_METADATA);
 538         clear_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags);
 539
 540         gfs2_glock_hold(gl);
 541         if (sdp->sd_lockstruct.ls_ops->lm_lock) {
 542                 /* lock_dlm */
 543                 ret = sdp->sd_lockstruct.ls_ops->lm_lock(gl, target, lck_flags);
 544                 if (ret) {
 545                         printk(KERN_ERR "GFS2: lm_lock ret %d\n", ret);
 546                         GLOCK_BUG_ON(gl, 1);
 547                 }
 548         } else { /* lock_nolock */
 549                 finish_xmote(gl, target);
 550                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 551                         gfs2_glock_put(gl);
 552         }
 553
 554         spin_lock(&gl->gl_spin);
 555 }
 556
 557 /**
 558  * find_first_holder - find the first "holder" gh
 559  * @gl: the glock
 560  */
 561
 562 static inline struct gfs2_holder *find_first_holder(const struct gfs2_glock *gl)
 563 {
 564         struct gfs2_holder *gh;
 565
 566         if (!list_empty(&gl->gl_holders)) {
 567                 gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
 568                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
 569                         return gh;
 570         }
 571         return NULL;
 572 }
 573
 574 /**
 575  * run_queue - do all outstanding tasks related to a glock
 576  * @gl: The glock in question
 577  * @nonblock: True if we must not block in run_queue
 578  *
 579  */
 580
 581 static void run_queue(struct gfs2_glock *gl, const int nonblock)
 582 __releases(&gl->gl_spin)
 583 __acquires(&gl->gl_spin)
 584 {
 585         struct gfs2_holder *gh = NULL;
 586         int ret;
 587
 588         if (test_and_set_bit(GLF_LOCK, &gl->gl_flags))
 589                 return;
 590
 591         GLOCK_BUG_ON(gl, test_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags));
 592
 593         if (test_bit(GLF_DEMOTE, &gl->gl_flags) &&
 594             gl->gl_demote_state != gl->gl_state) {
 595                 if (find_first_holder(gl))
 596                         goto out_unlock;
 597                 if (nonblock)
 598                         goto out_sched;
 599                 set_bit(GLF_DEMOTE_IN_PROGRESS, &gl->gl_flags);
 600                 GLOCK_BUG_ON(gl, gl->gl_demote_state == LM_ST_EXCLUSIVE);
 601                 gl->gl_target = gl->gl_demote_state;
 602         } else {
 603                 if (test_bit(GLF_DEMOTE, &gl->gl_flags))
 604                         gfs2_demote_wake(gl);
 605                 ret = do_promote(gl);
 606                 if (ret == 0)
 607                         goto out_unlock;
 608                 if (ret == 2)
 609                         goto out;
 610                 gh = find_first_waiter(gl);
 611                 gl->gl_target = gh->gh_state;
 612                 if (!(gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)))
 613                         do_error(gl, 0); /* Fail queued try locks */
 614         }
 615         do_xmote(gl, gh, gl->gl_target);
 616 out:
 617         return;
 618
 619 out_sched:
 620         clear_bit(GLF_LOCK, &gl->gl_flags);
 621         smp_mb__after_clear_bit();
 622         gl->gl_lockref.count++;
 623         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
 624                 gl->gl_lockref.count--;
 625         return;
 626
 627 out_unlock:
 628         clear_bit(GLF_LOCK, &gl->gl_flags);
 629         smp_mb__after_clear_bit();
 630         return;
 631 }
 632
 633 static void delete_work_func(struct work_struct *work)
 634 {
 635         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_delete);
 636         struct gfs2_sbd *sdp = gl->gl_sbd;
 637         struct gfs2_inode *ip;
 638         struct inode *inode;
 639         u64 no_addr = gl->gl_name.ln_number;
 640
 641         ip = gl->gl_object;
 642         /* Note: Unsafe to dereference ip as we don't hold right refs/locks */
 643
 644         if (ip)
 645                 inode = gfs2_ilookup(sdp->sd_vfs, no_addr, 1);
 646         else
 647                 inode = gfs2_lookup_by_inum(sdp, no_addr, NULL, GFS2_BLKST_UNLINKED);
 648         if (inode && !IS_ERR(inode)) {
 649                 d_prune_aliases(inode);
 650                 iput(inode);
 651         }
 652         gfs2_glock_put(gl);
 653 }
 654
 655 static void glock_work_func(struct work_struct *work)
 656 {
 657         unsigned long delay = 0;
 658         struct gfs2_glock *gl = container_of(work, struct gfs2_glock, gl_work.work);
 659         int drop_ref = 0;
 660
 661         if (test_and_clear_bit(GLF_REPLY_PENDING, &gl->gl_flags)) {
 662                 finish_xmote(gl, gl->gl_reply);
 663                 drop_ref = 1;
 664         }
 665         spin_lock(&gl->gl_spin);
 666         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
 667             gl->gl_state != LM_ST_UNLOCKED &&
 668             gl->gl_demote_state != LM_ST_EXCLUSIVE) {
 669                 unsigned long holdtime, now = jiffies;
 670
 671                 holdtime = gl->gl_tchange + gl->gl_hold_time;
 672                 if (time_before(now, holdtime))
 673                         delay = holdtime - now;
 674
 675                 if (!delay) {
 676                         clear_bit(GLF_PENDING_DEMOTE, &gl->gl_flags);
 677                         set_bit(GLF_DEMOTE, &gl->gl_flags);
 678                 }
 679         }
 680         run_queue(gl, 0);
 681         spin_unlock(&gl->gl_spin);
 682         if (!delay)
 683                 gfs2_glock_put(gl);
 684         else {
 685                 if (gl->gl_name.ln_type != LM_TYPE_INODE)
 686                         delay = 0;
 687                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
 688                         gfs2_glock_put(gl);
 689         }
 690         if (drop_ref)
 691                 gfs2_glock_put(gl);
 692 }
 693
 694 /**
 695  * gfs2_glock_get() - Get a glock, or create one if one doesn't exist
 696  * @sdp: The GFS2 superblock
 697  * @number: the lock number
 698  * @glops: The glock_operations to use
 699  * @create: If 0, don't create the glock if it doesn't exist
 700  * @glp: the glock is returned here
 701  *
 702  * This does not lock a glock, just finds/creates structures for one.
 703  *
 704  * Returns: errno
 705  */
 706
 707 int gfs2_glock_get(struct gfs2_sbd *sdp, u64 number,
 708                    const struct gfs2_glock_operations *glops, int create,
 709                    struct gfs2_glock **glp)
 710 {
 711         struct super_block *s = sdp->sd_vfs;
 712         struct lm_lockname name = { .ln_number = number, .ln_type = glops->go_type };
 713         struct gfs2_glock *gl, *tmp;
 714         unsigned int hash = gl_hash(sdp, &name);
 715         struct address_space *mapping;
 716         struct kmem_cache *cachep;
 717
 718         rcu_read_lock();
 719         gl = search_bucket(hash, sdp, &name);
 720         rcu_read_unlock();
 721
 722         *glp = gl;
 723         if (gl)
 724                 return 0;
 725         if (!create)
 726                 return -ENOENT;
 727
 728         if (glops->go_flags & GLOF_ASPACE)
 729                 cachep = gfs2_glock_aspace_cachep;
 730         else
 731                 cachep = gfs2_glock_cachep;
 732         gl = kmem_cache_alloc(cachep, GFP_KERNEL);
 733         if (!gl)
 734                 return -ENOMEM;
 735
 736         memset(&gl->gl_lksb, 0, sizeof(struct dlm_lksb));
 737
 738         if (glops->go_flags & GLOF_LVB) {
 739                 gl->gl_lksb.sb_lvbptr = kzalloc(GFS2_MIN_LVB_SIZE, GFP_KERNEL);
 740                 if (!gl->gl_lksb.sb_lvbptr) {
 741                         kmem_cache_free(cachep, gl);
 742                         return -ENOMEM;
 743                 }
 744         }
 745
 746         atomic_inc(&sdp->sd_glock_disposal);
 747         gl->gl_sbd = sdp;
 748         gl->gl_flags = 0;
 749         gl->gl_name = name;
 750         gl->gl_lockref.count = 1;
 751         gl->gl_state = LM_ST_UNLOCKED;
 752         gl->gl_target = LM_ST_UNLOCKED;
 753         gl->gl_demote_state = LM_ST_EXCLUSIVE;
 754         gl->gl_hash = hash;
 755         gl->gl_ops = glops;
 756         gl->gl_dstamp = ktime_set(0, 0);
 757         preempt_disable();
 758         /* We use the global stats to estimate the initial per-glock stats */
 759         gl->gl_stats = this_cpu_ptr(sdp->sd_lkstats)->lkstats[glops->go_type];
 760         preempt_enable();
 761         gl->gl_stats.stats[GFS2_LKS_DCOUNT] = 0;
 762         gl->gl_stats.stats[GFS2_LKS_QCOUNT] = 0;
 763         gl->gl_tchange = jiffies;
 764         gl->gl_object = NULL;
 765         gl->gl_hold_time = GL_GLOCK_DFT_HOLD;
 766         INIT_DELAYED_WORK(&gl->gl_work, glock_work_func);
 767         INIT_WORK(&gl->gl_delete, delete_work_func);
 768
 769         mapping = gfs2_glock2aspace(gl);
 770         if (mapping) {
 771                 mapping->a_ops = &gfs2_meta_aops;
 772                 mapping->host = s->s_bdev->bd_inode;
 773                 mapping->flags = 0;
 774                 mapping_set_gfp_mask(mapping, GFP_NOFS);
 775                 mapping->private_data = NULL;
 776                 mapping->backing_dev_info = s->s_bdi;
 777                 mapping->writeback_index = 0;
 778         }
 779
 780         spin_lock_bucket(hash);
 781         tmp = search_bucket(hash, sdp, &name);
 782         if (tmp) {
 783                 spin_unlock_bucket(hash);
 784                 kfree(gl->gl_lksb.sb_lvbptr);
 785                 kmem_cache_free(cachep, gl);
 786                 atomic_dec(&sdp->sd_glock_disposal);
 787                 gl = tmp;
 788         } else {
 789                 hlist_bl_add_head_rcu(&gl->gl_list, &gl_hash_table[hash]);
 790                 spin_unlock_bucket(hash);
 791         }
 792
 793         *glp = gl;
 794
 795         return 0;
 796 }
 797
 798 /**
 799  * gfs2_holder_init - initialize a struct gfs2_holder in the default way
 800  * @gl: the glock
 801  * @state: the state we're requesting
 802  * @flags: the modifier flags
 803  * @gh: the holder structure
 804  *
 805  */
 806
 807 void gfs2_holder_init(struct gfs2_glock *gl, unsigned int state, unsigned flags,
 808                       struct gfs2_holder *gh)
 809 {
 810         INIT_LIST_HEAD(&gh->gh_list);
 811         gh->gh_gl = gl;
 812         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 813         gh->gh_owner_pid = get_pid(task_pid(current));
 814         gh->gh_state = state;
 815         gh->gh_flags = flags;
 816         gh->gh_error = 0;
 817         gh->gh_iflags = 0;
 818         gfs2_glock_hold(gl);
 819 }
 820
 821 /**
 822  * gfs2_holder_reinit - reinitialize a struct gfs2_holder so we can requeue it
 823  * @state: the state we're requesting
 824  * @flags: the modifier flags
 825  * @gh: the holder structure
 826  *
 827  * Don't mess with the glock.
 828  *
 829  */
 830
 831 void gfs2_holder_reinit(unsigned int state, unsigned flags, struct gfs2_holder *gh)
 832 {
 833         gh->gh_state = state;
 834         gh->gh_flags = flags;
 835         gh->gh_iflags = 0;
 836         gh->gh_ip = (unsigned long)__builtin_return_address(0);
 837         if (gh->gh_owner_pid)
 838                 put_pid(gh->gh_owner_pid);
 839         gh->gh_owner_pid = get_pid(task_pid(current));
 840 }
 841
 842 /**
 843  * gfs2_holder_uninit - uninitialize a holder structure (drop glock reference)
 844  * @gh: the holder structure
 845  *
 846  */
 847
 848 void gfs2_holder_uninit(struct gfs2_holder *gh)
 849 {
 850         put_pid(gh->gh_owner_pid);
 851         gfs2_glock_put(gh->gh_gl);
 852         gh->gh_gl = NULL;
 853         gh->gh_ip = 0;
 854 }
 855
 856 /**
 857  * gfs2_glock_holder_wait
 858  * @word: unused
 859  *
 860  * This function and gfs2_glock_demote_wait both show up in the WCHAN
 861  * field. Thus I've separated these otherwise identical functions in
 862  * order to be more informative to the user.
 863  */
 864
 865 static int gfs2_glock_holder_wait(void *word)
 866 {
 867         schedule();
 868         return 0;
 869 }
 870
 871 static int gfs2_glock_demote_wait(void *word)
 872 {
 873         schedule();
 874         return 0;
 875 }
 876
 877 /**
 878  * gfs2_glock_wait - wait on a glock acquisition
 879  * @gh: the glock holder
 880  *
 881  * Returns: 0 on success
 882  */
 883
 884 int gfs2_glock_wait(struct gfs2_holder *gh)
 885 {
 886         unsigned long time1 = jiffies;
 887
 888         might_sleep();
 889         wait_on_bit(&gh->gh_iflags, HIF_WAIT, gfs2_glock_holder_wait, TASK_UNINTERRUPTIBLE);
 890         if (time_after(jiffies, time1 + HZ)) /* have we waited > a second? */
 891                 /* Lengthen the minimum hold time. */
 892                 gh->gh_gl->gl_hold_time = min(gh->gh_gl->gl_hold_time +
 893                                               GL_GLOCK_HOLD_INCR,
 894                                               GL_GLOCK_MAX_HOLD);
 895         return gh->gh_error;
 896 }
 897
 898 /**
 899  * handle_callback - process a demote request
 900  * @gl: the glock
 901  * @state: the state the caller wants us to change to
 902  *
 903  * There are only two requests that we are going to see in actual
 904  * practise: LM_ST_SHARED and LM_ST_UNLOCKED
 905  */
 906
 907 static void handle_callback(struct gfs2_glock *gl, unsigned int state,
 908                             unsigned long delay, bool remote)
 909 {
 910         int bit = delay ? GLF_PENDING_DEMOTE : GLF_DEMOTE;
 911
 912         set_bit(bit, &gl->gl_flags);
 913         if (gl->gl_demote_state == LM_ST_EXCLUSIVE) {
 914                 gl->gl_demote_state = state;
 915                 gl->gl_demote_time = jiffies;
 916         } else if (gl->gl_demote_state != LM_ST_UNLOCKED &&
 917                         gl->gl_demote_state != state) {
 918                 gl->gl_demote_state = LM_ST_UNLOCKED;
 919         }
 920         if (gl->gl_ops->go_callback)
 921                 gl->gl_ops->go_callback(gl, remote);
 922         trace_gfs2_demote_rq(gl, remote);
 923 }
 924
 925 void gfs2_print_dbg(struct seq_file *seq, const char *fmt, ...)
 926 {
 927         struct va_format vaf;
 928         va_list args;
 929
 930         va_start(args, fmt);
 931
 932         if (seq) {
 933                 seq_vprintf(seq, fmt, args);
 934         } else {
 935                 vaf.fmt = fmt;
 936                 vaf.va = &args;
 937
 938                 printk(KERN_ERR " %pV", &vaf);
 939         }
 940
 941         va_end(args);
 942 }
 943
 944 /**
 945  * add_to_queue - Add a holder to the wait queue (but look for recursion)
 946  * @gh: the holder structure to add
 947  *
 948  * Eventually we should move the recursive locking trap to a
 949  * debugging option or something like that. This is the fast
 950  * path and needs to have the minimum number of distractions.
 951  *
 952  */
 953
 954 static inline void add_to_queue(struct gfs2_holder *gh)
 955 __releases(&gl->gl_spin)
 956 __acquires(&gl->gl_spin)
 957 {
 958         struct gfs2_glock *gl = gh->gh_gl;
 959         struct gfs2_sbd *sdp = gl->gl_sbd;
 960         struct list_head *insert_pt = NULL;
 961         struct gfs2_holder *gh2;
 962         int try_futile = 0;
 963
 964         BUG_ON(gh->gh_owner_pid == NULL);
 965         if (test_and_set_bit(HIF_WAIT, &gh->gh_iflags))
 966                 BUG();
 967
 968         if (gh->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB)) {
 969                 if (test_bit(GLF_LOCK, &gl->gl_flags))
 970                         try_futile = !may_grant(gl, gh);
 971                 if (test_bit(GLF_INVALIDATE_IN_PROGRESS, &gl->gl_flags))
 972                         goto fail;
 973         }
 974
 975         list_for_each_entry(gh2, &gl->gl_holders, gh_list) {
 976                 if (unlikely(gh2->gh_owner_pid == gh->gh_owner_pid &&
 977                     (gh->gh_gl->gl_ops->go_type != LM_TYPE_FLOCK)))
 978                         goto trap_recursive;
 979                 if (try_futile &&
 980                     !(gh2->gh_flags & (LM_FLAG_TRY | LM_FLAG_TRY_1CB))) {
 981 fail:
 982                         gh->gh_error = GLR_TRYFAILED;
 983                         gfs2_holder_wake(gh);
 984                         return;
 985                 }
 986                 if (test_bit(HIF_HOLDER, &gh2->gh_iflags))
 987                         continue;
 988                 if (unlikely((gh->gh_flags & LM_FLAG_PRIORITY) && !insert_pt))
 989                         insert_pt = &gh2->gh_list;
 990         }
 991         set_bit(GLF_QUEUED, &gl->gl_flags);
 992         trace_gfs2_glock_queue(gh, 1);
 993         gfs2_glstats_inc(gl, GFS2_LKS_QCOUNT);
 994         gfs2_sbstats_inc(gl, GFS2_LKS_QCOUNT);
 995         if (likely(insert_pt == NULL)) {
 996                 list_add_tail(&gh->gh_list, &gl->gl_holders);
 997                 if (unlikely(gh->gh_flags & LM_FLAG_PRIORITY))
 998                         goto do_cancel;
 999                 return;
1000         }
1001         list_add_tail(&gh->gh_list, insert_pt);
1002 do_cancel:
1003         gh = list_entry(gl->gl_holders.next, struct gfs2_holder, gh_list);
1004         if (!(gh->gh_flags & LM_FLAG_PRIORITY)) {
1005                 spin_unlock(&gl->gl_spin);
1006                 if (sdp->sd_lockstruct.ls_ops->lm_cancel)
1007                         sdp->sd_lockstruct.ls_ops->lm_cancel(gl);
1008                 spin_lock(&gl->gl_spin);
1009         }
1010         return;
1011
1012 trap_recursive:
1013         printk(KERN_ERR "original: %pSR\n", (void *)gh2->gh_ip);
1014         printk(KERN_ERR "pid: %d\n", pid_nr(gh2->gh_owner_pid));
1015         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1016                gh2->gh_gl->gl_name.ln_type, gh2->gh_state);
1017         printk(KERN_ERR "new: %pSR\n", (void *)gh->gh_ip);
1018         printk(KERN_ERR "pid: %d\n", pid_nr(gh->gh_owner_pid));
1019         printk(KERN_ERR "lock type: %d req lock state : %d\n",
1020                gh->gh_gl->gl_name.ln_type, gh->gh_state);
1021         gfs2_dump_glock(NULL, gl);
1022         BUG();
1023 }
1024
1025 /**
1026  * gfs2_glock_nq - enqueue a struct gfs2_holder onto a glock (acquire a glock)
1027  * @gh: the holder structure
1028  *
1029  * if (gh->gh_flags & GL_ASYNC), this never returns an error
1030  *
1031  * Returns: 0, GLR_TRYFAILED, or errno on failure
1032  */
1033
1034 int gfs2_glock_nq(struct gfs2_holder *gh)
1035 {
1036         struct gfs2_glock *gl = gh->gh_gl;
1037         struct gfs2_sbd *sdp = gl->gl_sbd;
1038         int error = 0;
1039
1040         if (unlikely(test_bit(SDF_SHUTDOWN, &sdp->sd_flags)))
1041                 return -EIO;
1042
1043         if (test_bit(GLF_LRU, &gl->gl_flags))
1044                 gfs2_glock_remove_from_lru(gl);
1045
1046         spin_lock(&gl->gl_spin);
1047         add_to_queue(gh);
1048         if ((LM_FLAG_NOEXP & gh->gh_flags) &&
1049             test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1050                 set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1051         run_queue(gl, 1);
1052         spin_unlock(&gl->gl_spin);
1053
1054         if (!(gh->gh_flags & GL_ASYNC))
1055                 error = gfs2_glock_wait(gh);
1056
1057         return error;
1058 }
1059
1060 /**
1061  * gfs2_glock_poll - poll to see if an async request has been completed
1062  * @gh: the holder
1063  *
1064  * Returns: 1 if the request is ready to be gfs2_glock_wait()ed on
1065  */
1066
1067 int gfs2_glock_poll(struct gfs2_holder *gh)
1068 {
1069         return test_bit(HIF_WAIT, &gh->gh_iflags) ? 0 : 1;
1070 }
1071
1072 /**
1073  * gfs2_glock_dq - dequeue a struct gfs2_holder from a glock (release a glock)
1074  * @gh: the glock holder
1075  *
1076  */
1077
1078 void gfs2_glock_dq(struct gfs2_holder *gh)
1079 {
1080         struct gfs2_glock *gl = gh->gh_gl;
1081         const struct gfs2_glock_operations *glops = gl->gl_ops;
1082         unsigned delay = 0;
1083         int fast_path = 0;
1084
1085         spin_lock(&gl->gl_spin);
1086         if (gh->gh_flags & GL_NOCACHE)
1087                 handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1088
1089         list_del_init(&gh->gh_list);
1090         if (find_first_holder(gl) == NULL) {
1091                 if (glops->go_unlock) {
1092                         GLOCK_BUG_ON(gl, test_and_set_bit(GLF_LOCK, &gl->gl_flags));
1093                         spin_unlock(&gl->gl_spin);
1094                         glops->go_unlock(gh);
1095                         spin_lock(&gl->gl_spin);
1096                         clear_bit(GLF_LOCK, &gl->gl_flags);
1097                 }
1098                 if (list_empty(&gl->gl_holders) &&
1099                     !test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1100                     !test_bit(GLF_DEMOTE, &gl->gl_flags))
1101                         fast_path = 1;
1102         }
1103         if (!test_bit(GLF_LFLUSH, &gl->gl_flags) && demote_ok(gl))
1104                 gfs2_glock_add_to_lru(gl);
1105
1106         trace_gfs2_glock_queue(gh, 0);
1107         spin_unlock(&gl->gl_spin);
1108         if (likely(fast_path))
1109                 return;
1110
1111         gfs2_glock_hold(gl);
1112         if (test_bit(GLF_PENDING_DEMOTE, &gl->gl_flags) &&
1113             !test_bit(GLF_DEMOTE, &gl->gl_flags) &&
1114             gl->gl_name.ln_type == LM_TYPE_INODE)
1115                 delay = gl->gl_hold_time;
1116         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1117                 gfs2_glock_put(gl);
1118 }
1119
1120 void gfs2_glock_dq_wait(struct gfs2_holder *gh)
1121 {
1122         struct gfs2_glock *gl = gh->gh_gl;
1123         gfs2_glock_dq(gh);
1124         might_sleep();
1125         wait_on_bit(&gl->gl_flags, GLF_DEMOTE, gfs2_glock_demote_wait, TASK_UNINTERRUPTIBLE);
1126 }
1127
1128 /**
1129  * gfs2_glock_dq_uninit - dequeue a holder from a glock and initialize it
1130  * @gh: the holder structure
1131  *
1132  */
1133
1134 void gfs2_glock_dq_uninit(struct gfs2_holder *gh)
1135 {
1136         gfs2_glock_dq(gh);
1137         gfs2_holder_uninit(gh);
1138 }
1139
1140 /**
1141  * gfs2_glock_nq_num - acquire a glock based on lock number
1142  * @sdp: the filesystem
1143  * @number: the lock number
1144  * @glops: the glock operations for the type of glock
1145  * @state: the state to acquire the glock in
1146  * @flags: modifier flags for the acquisition
1147  * @gh: the struct gfs2_holder
1148  *
1149  * Returns: errno
1150  */
1151
1152 int gfs2_glock_nq_num(struct gfs2_sbd *sdp, u64 number,
1153                       const struct gfs2_glock_operations *glops,
1154                       unsigned int state, int flags, struct gfs2_holder *gh)
1155 {
1156         struct gfs2_glock *gl;
1157         int error;
1158
1159         error = gfs2_glock_get(sdp, number, glops, CREATE, &gl);
1160         if (!error) {
1161                 error = gfs2_glock_nq_init(gl, state, flags, gh);
1162                 gfs2_glock_put(gl);
1163         }
1164
1165         return error;
1166 }
1167
1168 /**
1169  * glock_compare - Compare two struct gfs2_glock structures for sorting
1170  * @arg_a: the first structure
1171  * @arg_b: the second structure
1172  *
1173  */
1174
1175 static int glock_compare(const void *arg_a, const void *arg_b)
1176 {
1177         const struct gfs2_holder *gh_a = *(const struct gfs2_holder **)arg_a;
1178         const struct gfs2_holder *gh_b = *(const struct gfs2_holder **)arg_b;
1179         const struct lm_lockname *a = &gh_a->gh_gl->gl_name;
1180         const struct lm_lockname *b = &gh_b->gh_gl->gl_name;
1181
1182         if (a->ln_number > b->ln_number)
1183                 return 1;
1184         if (a->ln_number < b->ln_number)
1185                 return -1;
1186         BUG_ON(gh_a->gh_gl->gl_ops->go_type == gh_b->gh_gl->gl_ops->go_type);
1187         return 0;
1188 }
1189
1190 /**
1191  * nq_m_sync - synchonously acquire more than one glock in deadlock free order
1192  * @num_gh: the number of structures
1193  * @ghs: an array of struct gfs2_holder structures
1194  *
1195  * Returns: 0 on success (all glocks acquired),
1196  *          errno on failure (no glocks acquired)
1197  */
1198
1199 static int nq_m_sync(unsigned int num_gh, struct gfs2_holder *ghs,
1200                      struct gfs2_holder **p)
1201 {
1202         unsigned int x;
1203         int error = 0;
1204
1205         for (x = 0; x < num_gh; x++)
1206                 p[x] = &ghs[x];
1207
1208         sort(p, num_gh, sizeof(struct gfs2_holder *), glock_compare, NULL);
1209
1210         for (x = 0; x < num_gh; x++) {
1211                 p[x]->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1212
1213                 error = gfs2_glock_nq(p[x]);
1214                 if (error) {
1215                         while (x--)
1216                                 gfs2_glock_dq(p[x]);
1217                         break;
1218                 }
1219         }
1220
1221         return error;
1222 }
1223
1224 /**
1225  * gfs2_glock_nq_m - acquire multiple glocks
1226  * @num_gh: the number of structures
1227  * @ghs: an array of struct gfs2_holder structures
1228  *
1229  *
1230  * Returns: 0 on success (all glocks acquired),
1231  *          errno on failure (no glocks acquired)
1232  */
1233
1234 int gfs2_glock_nq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1235 {
1236         struct gfs2_holder *tmp[4];
1237         struct gfs2_holder **pph = tmp;
1238         int error = 0;
1239
1240         switch(num_gh) {
1241         case 0:
1242                 return 0;
1243         case 1:
1244                 ghs->gh_flags &= ~(LM_FLAG_TRY | GL_ASYNC);
1245                 return gfs2_glock_nq(ghs);
1246         default:
1247                 if (num_gh <= 4)
1248                         break;
1249                 pph = kmalloc(num_gh * sizeof(struct gfs2_holder *), GFP_NOFS);
1250                 if (!pph)
1251                         return -ENOMEM;
1252         }
1253
1254         error = nq_m_sync(num_gh, ghs, pph);
1255
1256         if (pph != tmp)
1257                 kfree(pph);
1258
1259         return error;
1260 }
1261
1262 /**
1263  * gfs2_glock_dq_m - release multiple glocks
1264  * @num_gh: the number of structures
1265  * @ghs: an array of struct gfs2_holder structures
1266  *
1267  */
1268
1269 void gfs2_glock_dq_m(unsigned int num_gh, struct gfs2_holder *ghs)
1270 {
1271         while (num_gh--)
1272                 gfs2_glock_dq(&ghs[num_gh]);
1273 }
1274
1275 void gfs2_glock_cb(struct gfs2_glock *gl, unsigned int state)
1276 {
1277         unsigned long delay = 0;
1278         unsigned long holdtime;
1279         unsigned long now = jiffies;
1280
1281         gfs2_glock_hold(gl);
1282         holdtime = gl->gl_tchange + gl->gl_hold_time;
1283         if (test_bit(GLF_QUEUED, &gl->gl_flags) &&
1284             gl->gl_name.ln_type == LM_TYPE_INODE) {
1285                 if (time_before(now, holdtime))
1286                         delay = holdtime - now;
1287                 if (test_bit(GLF_REPLY_PENDING, &gl->gl_flags))
1288                         delay = gl->gl_hold_time;
1289         }
1290
1291         spin_lock(&gl->gl_spin);
1292         handle_callback(gl, state, delay, true);
1293         spin_unlock(&gl->gl_spin);
1294         if (queue_delayed_work(glock_workqueue, &gl->gl_work, delay) == 0)
1295                 gfs2_glock_put(gl);
1296 }
1297
1298 /**
1299  * gfs2_should_freeze - Figure out if glock should be frozen
1300  * @gl: The glock in question
1301  *
1302  * Glocks are not frozen if (a) the result of the dlm operation is
1303  * an error, (b) the locking operation was an unlock operation or
1304  * (c) if there is a "noexp" flagged request anywhere in the queue
1305  *
1306  * Returns: 1 if freezing should occur, 0 otherwise
1307  */
1308
1309 static int gfs2_should_freeze(const struct gfs2_glock *gl)
1310 {
1311         const struct gfs2_holder *gh;
1312
1313         if (gl->gl_reply & ~LM_OUT_ST_MASK)
1314                 return 0;
1315         if (gl->gl_target == LM_ST_UNLOCKED)
1316                 return 0;
1317
1318         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1319                 if (test_bit(HIF_HOLDER, &gh->gh_iflags))
1320                         continue;
1321                 if (LM_FLAG_NOEXP & gh->gh_flags)
1322                         return 0;
1323         }
1324
1325         return 1;
1326 }
1327
1328 /**
1329  * gfs2_glock_complete - Callback used by locking
1330  * @gl: Pointer to the glock
1331  * @ret: The return value from the dlm
1332  *
1333  * The gl_reply field is under the gl_spin lock so that it is ok
1334  * to use a bitfield shared with other glock state fields.
1335  */
1336
1337 void gfs2_glock_complete(struct gfs2_glock *gl, int ret)
1338 {
1339         struct lm_lockstruct *ls = &gl->gl_sbd->sd_lockstruct;
1340
1341         spin_lock(&gl->gl_spin);
1342         gl->gl_reply = ret;
1343
1344         if (unlikely(test_bit(DFL_BLOCK_LOCKS, &ls->ls_recover_flags))) {
1345                 if (gfs2_should_freeze(gl)) {
1346                         set_bit(GLF_FROZEN, &gl->gl_flags);
1347                         spin_unlock(&gl->gl_spin);
1348                         return;
1349                 }
1350         }
1351
1352         gl->gl_lockref.count++;
1353         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1354         spin_unlock(&gl->gl_spin);
1355
1356         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1357                 gfs2_glock_put(gl);
1358 }
1359
1360 static int glock_cmp(void *priv, struct list_head *a, struct list_head *b)
1361 {
1362         struct gfs2_glock *gla, *glb;
1363
1364         gla = list_entry(a, struct gfs2_glock, gl_lru);
1365         glb = list_entry(b, struct gfs2_glock, gl_lru);
1366
1367         if (gla->gl_name.ln_number > glb->gl_name.ln_number)
1368                 return 1;
1369         if (gla->gl_name.ln_number < glb->gl_name.ln_number)
1370                 return -1;
1371
1372         return 0;
1373 }
1374
1375 /**
1376  * gfs2_dispose_glock_lru - Demote a list of glocks
1377  * @list: The list to dispose of
1378  *
1379  * Disposing of glocks may involve disk accesses, so that here we sort
1380  * the glocks by number (i.e. disk location of the inodes) so that if
1381  * there are any such accesses, they'll be sent in order (mostly).
1382  *
1383  * Must be called under the lru_lock, but may drop and retake this
1384  * lock. While the lru_lock is dropped, entries may vanish from the
1385  * list, but no new entries will appear on the list (since it is
1386  * private)
1387  */
1388
1389 static void gfs2_dispose_glock_lru(struct list_head *list)
1390 __releases(&lru_lock)
1391 __acquires(&lru_lock)
1392 {
1393         struct gfs2_glock *gl;
1394
1395         list_sort(NULL, list, glock_cmp);
1396
1397         while(!list_empty(list)) {
1398                 gl = list_entry(list->next, struct gfs2_glock, gl_lru);
1399                 list_del_init(&gl->gl_lru);
1400                 if (!spin_trylock(&gl->gl_spin)) {
1401                         list_add(&gl->gl_lru, &lru_list);
1402                         atomic_inc(&lru_count);
1403                         continue;
1404                 }
1405                 clear_bit(GLF_LRU, &gl->gl_flags);
1406                 spin_unlock(&lru_lock);
1407                 gl->gl_lockref.count++;
1408                 if (demote_ok(gl))
1409                         handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1410                 WARN_ON(!test_and_clear_bit(GLF_LOCK, &gl->gl_flags));
1411                 if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1412                         gl->gl_lockref.count--;
1413                 spin_unlock(&gl->gl_spin);
1414                 spin_lock(&lru_lock);
1415         }
1416 }
1417
1418 /**
1419  * gfs2_scan_glock_lru - Scan the LRU looking for locks to demote
1420  * @nr: The number of entries to scan
1421  *
1422  * This function selects the entries on the LRU which are able to
1423  * be demoted, and then kicks off the process by calling
1424  * gfs2_dispose_glock_lru() above.
1425  */
1426
1427 static long gfs2_scan_glock_lru(int nr)
1428 {
1429         struct gfs2_glock *gl;
1430         LIST_HEAD(skipped);
1431         LIST_HEAD(dispose);
1432         long freed = 0;
1433
1434         spin_lock(&lru_lock);
1435         while ((nr-- >= 0) && !list_empty(&lru_list)) {
1436                 gl = list_entry(lru_list.next, struct gfs2_glock, gl_lru);
1437
1438                 /* Test for being demotable */
1439                 if (!test_and_set_bit(GLF_LOCK, &gl->gl_flags)) {
1440                         list_move(&gl->gl_lru, &dispose);
1441                         atomic_dec(&lru_count);
1442                         freed++;
1443                         continue;
1444                 }
1445
1446                 list_move(&gl->gl_lru, &skipped);
1447         }
1448         list_splice(&skipped, &lru_list);
1449         if (!list_empty(&dispose))
1450                 gfs2_dispose_glock_lru(&dispose);
1451         spin_unlock(&lru_lock);
1452
1453         return freed;
1454 }
1455
1456 static unsigned long gfs2_glock_shrink_scan(struct shrinker *shrink,
1457                                             struct shrink_control *sc)
1458 {
1459         if (!(sc->gfp_mask & __GFP_FS))
1460                 return SHRINK_STOP;
1461         return gfs2_scan_glock_lru(sc->nr_to_scan);
1462 }
1463
1464 static unsigned long gfs2_glock_shrink_count(struct shrinker *shrink,
1465                                              struct shrink_control *sc)
1466 {
1467         return vfs_pressure_ratio(atomic_read(&lru_count));
1468 }
1469
1470 static struct shrinker glock_shrinker = {
1471         .seeks = DEFAULT_SEEKS,
1472         .count_objects = gfs2_glock_shrink_count,
1473         .scan_objects = gfs2_glock_shrink_scan,
1474 };
1475
1476 /**
1477  * examine_bucket - Call a function for glock in a hash bucket
1478  * @examiner: the function
1479  * @sdp: the filesystem
1480  * @bucket: the bucket
1481  *
1482  */
1483
1484 static void examine_bucket(glock_examiner examiner, const struct gfs2_sbd *sdp,
1485                           unsigned int hash)
1486 {
1487         struct gfs2_glock *gl;
1488         struct hlist_bl_head *head = &gl_hash_table[hash];
1489         struct hlist_bl_node *pos;
1490
1491         rcu_read_lock();
1492         hlist_bl_for_each_entry_rcu(gl, pos, head, gl_list) {
1493                 if ((gl->gl_sbd == sdp) && lockref_get_not_dead(&gl->gl_lockref))
1494                         examiner(gl);
1495         }
1496         rcu_read_unlock();
1497         cond_resched();
1498 }
1499
1500 static void glock_hash_walk(glock_examiner examiner, const struct gfs2_sbd *sdp)
1501 {
1502         unsigned x;
1503
1504         for (x = 0; x < GFS2_GL_HASH_SIZE; x++)
1505                 examine_bucket(examiner, sdp, x);
1506 }
1507
1508
1509 /**
1510  * thaw_glock - thaw out a glock which has an unprocessed reply waiting
1511  * @gl: The glock to thaw
1512  *
1513  */
1514
1515 static void thaw_glock(struct gfs2_glock *gl)
1516 {
1517         if (!test_and_clear_bit(GLF_FROZEN, &gl->gl_flags))
1518                 goto out;
1519         set_bit(GLF_REPLY_PENDING, &gl->gl_flags);
1520         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0) {
1521 out:
1522                 gfs2_glock_put(gl);
1523         }
1524 }
1525
1526 /**
1527  * clear_glock - look at a glock and see if we can free it from glock cache
1528  * @gl: the glock to look at
1529  *
1530  */
1531
1532 static void clear_glock(struct gfs2_glock *gl)
1533 {
1534         gfs2_glock_remove_from_lru(gl);
1535
1536         spin_lock(&gl->gl_spin);
1537         if (gl->gl_state != LM_ST_UNLOCKED)
1538                 handle_callback(gl, LM_ST_UNLOCKED, 0, false);
1539         spin_unlock(&gl->gl_spin);
1540         if (queue_delayed_work(glock_workqueue, &gl->gl_work, 0) == 0)
1541                 gfs2_glock_put(gl);
1542 }
1543
1544 /**
1545  * gfs2_glock_thaw - Thaw any frozen glocks
1546  * @sdp: The super block
1547  *
1548  */
1549
1550 void gfs2_glock_thaw(struct gfs2_sbd *sdp)
1551 {
1552         glock_hash_walk(thaw_glock, sdp);
1553 }
1554
1555 static int dump_glock(struct seq_file *seq, struct gfs2_glock *gl)
1556 {
1557         int ret;
1558         spin_lock(&gl->gl_spin);
1559         ret = gfs2_dump_glock(seq, gl);
1560         spin_unlock(&gl->gl_spin);
1561         return ret;
1562 }
1563
1564 static void dump_glock_func(struct gfs2_glock *gl)
1565 {
1566         dump_glock(NULL, gl);
1567 }
1568
1569 /**
1570  * gfs2_gl_hash_clear - Empty out the glock hash table
1571  * @sdp: the filesystem
1572  * @wait: wait until it's all gone
1573  *
1574  * Called when unmounting the filesystem.
1575  */
1576
1577 void gfs2_gl_hash_clear(struct gfs2_sbd *sdp)
1578 {
1579         set_bit(SDF_SKIP_DLM_UNLOCK, &sdp->sd_flags);
1580         flush_workqueue(glock_workqueue);
1581         glock_hash_walk(clear_glock, sdp);
1582         flush_workqueue(glock_workqueue);
1583         wait_event(sdp->sd_glock_wait, atomic_read(&sdp->sd_glock_disposal) == 0);
1584         glock_hash_walk(dump_glock_func, sdp);
1585 }
1586
1587 void gfs2_glock_finish_truncate(struct gfs2_inode *ip)
1588 {
1589         struct gfs2_glock *gl = ip->i_gl;
1590         int ret;
1591
1592         ret = gfs2_truncatei_resume(ip);
1593         gfs2_assert_withdraw(gl->gl_sbd, ret == 0);
1594
1595         spin_lock(&gl->gl_spin);
1596         clear_bit(GLF_LOCK, &gl->gl_flags);
1597         run_queue(gl, 1);
1598         spin_unlock(&gl->gl_spin);
1599 }
1600
1601 static const char *state2str(unsigned state)
1602 {
1603         switch(state) {
1604         case LM_ST_UNLOCKED:
1605                 return "UN";
1606         case LM_ST_SHARED:
1607                 return "SH";
1608         case LM_ST_DEFERRED:
1609                 return "DF";
1610         case LM_ST_EXCLUSIVE:
1611                 return "EX";
1612         }
1613         return "??";
1614 }
1615
1616 static const char *hflags2str(char *buf, unsigned flags, unsigned long iflags)
1617 {
1618         char *p = buf;
1619         if (flags & LM_FLAG_TRY)
1620                 *p++ = 't';
1621         if (flags & LM_FLAG_TRY_1CB)
1622                 *p++ = 'T';
1623         if (flags & LM_FLAG_NOEXP)
1624                 *p++ = 'e';
1625         if (flags & LM_FLAG_ANY)
1626                 *p++ = 'A';
1627         if (flags & LM_FLAG_PRIORITY)
1628                 *p++ = 'p';
1629         if (flags & GL_ASYNC)
1630                 *p++ = 'a';
1631         if (flags & GL_EXACT)
1632                 *p++ = 'E';
1633         if (flags & GL_NOCACHE)
1634                 *p++ = 'c';
1635         if (test_bit(HIF_HOLDER, &iflags))
1636                 *p++ = 'H';
1637         if (test_bit(HIF_WAIT, &iflags))
1638                 *p++ = 'W';
1639         if (test_bit(HIF_FIRST, &iflags))
1640                 *p++ = 'F';
1641         *p = 0;
1642         return buf;
1643 }
1644
1645 /**
1646  * dump_holder - print information about a glock holder
1647  * @seq: the seq_file struct
1648  * @gh: the glock holder
1649  *
1650  * Returns: 0 on success, -ENOBUFS when we run out of space
1651  */
1652
1653 static int dump_holder(struct seq_file *seq, const struct gfs2_holder *gh)
1654 {
1655         struct task_struct *gh_owner = NULL;
1656         char flags_buf[32];
1657
1658         if (gh->gh_owner_pid)
1659                 gh_owner = pid_task(gh->gh_owner_pid, PIDTYPE_PID);
1660         gfs2_print_dbg(seq, " H: s:%s f:%s e:%d p:%ld [%s] %pS\n",
1661                        state2str(gh->gh_state),
1662                        hflags2str(flags_buf, gh->gh_flags, gh->gh_iflags),
1663                        gh->gh_error,
1664                        gh->gh_owner_pid ? (long)pid_nr(gh->gh_owner_pid) : -1,
1665                        gh_owner ? gh_owner->comm : "(ended)",
1666                        (void *)gh->gh_ip);
1667         return 0;
1668 }
1669
1670 static const char *gflags2str(char *buf, const struct gfs2_glock *gl)
1671 {
1672         const unsigned long *gflags = &gl->gl_flags;
1673         char *p = buf;
1674
1675         if (test_bit(GLF_LOCK, gflags))
1676                 *p++ = 'l';
1677         if (test_bit(GLF_DEMOTE, gflags))
1678                 *p++ = 'D';
1679         if (test_bit(GLF_PENDING_DEMOTE, gflags))
1680                 *p++ = 'd';
1681         if (test_bit(GLF_DEMOTE_IN_PROGRESS, gflags))
1682                 *p++ = 'p';
1683         if (test_bit(GLF_DIRTY, gflags))
1684                 *p++ = 'y';
1685         if (test_bit(GLF_LFLUSH, gflags))
1686                 *p++ = 'f';
1687         if (test_bit(GLF_INVALIDATE_IN_PROGRESS, gflags))
1688                 *p++ = 'i';
1689         if (test_bit(GLF_REPLY_PENDING, gflags))
1690                 *p++ = 'r';
1691         if (test_bit(GLF_INITIAL, gflags))
1692                 *p++ = 'I';
1693         if (test_bit(GLF_FROZEN, gflags))
1694                 *p++ = 'F';
1695         if (test_bit(GLF_QUEUED, gflags))
1696                 *p++ = 'q';
1697         if (test_bit(GLF_LRU, gflags))
1698                 *p++ = 'L';
1699         if (gl->gl_object)
1700                 *p++ = 'o';
1701         if (test_bit(GLF_BLOCKING, gflags))
1702                 *p++ = 'b';
1703         *p = 0;
1704         return buf;
1705 }
1706
1707 /**
1708  * gfs2_dump_glock - print information about a glock
1709  * @seq: The seq_file struct
1710  * @gl: the glock
1711  *
1712  * The file format is as follows:
1713  * One line per object, capital letters are used to indicate objects
1714  * G = glock, I = Inode, R = rgrp, H = holder. Glocks are not indented,
1715  * other objects are indented by a single space and follow the glock to
1716  * which they are related. Fields are indicated by lower case letters
1717  * followed by a colon and the field value, except for strings which are in
1718  * [] so that its possible to see if they are composed of spaces for
1719  * example. The field's are n = number (id of the object), f = flags,
1720  * t = type, s = state, r = refcount, e = error, p = pid.
1721  *
1722  * Returns: 0 on success, -ENOBUFS when we run out of space
1723  */
1724
1725 int gfs2_dump_glock(struct seq_file *seq, const struct gfs2_glock *gl)
1726 {
1727         const struct gfs2_glock_operations *glops = gl->gl_ops;
1728         unsigned long long dtime;
1729         const struct gfs2_holder *gh;
1730         char gflags_buf[32];
1731         int error = 0;
1732
1733         dtime = jiffies - gl->gl_demote_time;
1734         dtime *= 1000000/HZ; /* demote time in uSec */
1735         if (!test_bit(GLF_DEMOTE, &gl->gl_flags))
1736                 dtime = 0;
1737         gfs2_print_dbg(seq, "G:  s:%s n:%u/%llx f:%s t:%s d:%s/%llu a:%d v:%d r:%d m:%ld\n",
1738                   state2str(gl->gl_state),
1739                   gl->gl_name.ln_type,
1740                   (unsigned long long)gl->gl_name.ln_number,
1741                   gflags2str(gflags_buf, gl),
1742                   state2str(gl->gl_target),
1743                   state2str(gl->gl_demote_state), dtime,
1744                   atomic_read(&gl->gl_ail_count),
1745                   atomic_read(&gl->gl_revokes),
1746                   (int)gl->gl_lockref.count, gl->gl_hold_time);
1747
1748         list_for_each_entry(gh, &gl->gl_holders, gh_list) {
1749                 error = dump_holder(seq, gh);
1750                 if (error)
1751                         goto out;
1752         }
1753         if (gl->gl_state != LM_ST_UNLOCKED && glops->go_dump)
1754                 error = glops->go_dump(seq, gl);
1755 out:
1756         return error;
1757 }
1758
1759 static int gfs2_glstats_seq_show(struct seq_file *seq, void *iter_ptr)
1760 {
1761         struct gfs2_glock *gl = iter_ptr;
1762
1763         seq_printf(seq, "G: n:%u/%llx rtt:%lld/%lld rttb:%lld/%lld irt:%lld/%lld dcnt: %lld qcnt: %lld\n",
1764                    gl->gl_name.ln_type,
1765                    (unsigned long long)gl->gl_name.ln_number,
1766                    (long long)gl->gl_stats.stats[GFS2_LKS_SRTT],
1767                    (long long)gl->gl_stats.stats[GFS2_LKS_SRTTVAR],
1768                    (long long)gl->gl_stats.stats[GFS2_LKS_SRTTB],
1769                    (long long)gl->gl_stats.stats[GFS2_LKS_SRTTVARB],
1770                    (long long)gl->gl_stats.stats[GFS2_LKS_SIRT],
1771                    (long long)gl->gl_stats.stats[GFS2_LKS_SIRTVAR],
1772                    (long long)gl->gl_stats.stats[GFS2_LKS_DCOUNT],
1773                    (long long)gl->gl_stats.stats[GFS2_LKS_QCOUNT]);
1774         return 0;
1775 }
1776
1777 static const char *gfs2_gltype[] = {
1778         "type",
1779         "reserved",
1780         "nondisk",
1781         "inode",
1782         "rgrp",
1783         "meta",
1784         "iopen",
1785         "flock",
1786         "plock",
1787         "quota",
1788         "journal",
1789 };
1790
1791 static const char *gfs2_stype[] = {
1792         [GFS2_LKS_SRTT]         = "srtt",
1793         [GFS2_LKS_SRTTVAR]      = "srttvar",
1794         [GFS2_LKS_SRTTB]        = "srttb",
1795         [GFS2_LKS_SRTTVARB]     = "srttvarb",
1796         [GFS2_LKS_SIRT]         = "sirt",
1797         [GFS2_LKS_SIRTVAR]      = "sirtvar",
1798         [GFS2_LKS_DCOUNT]       = "dlm",
1799         [GFS2_LKS_QCOUNT]       = "queue",
1800 };
1801
1802 #define GFS2_NR_SBSTATS (ARRAY_SIZE(gfs2_gltype) * ARRAY_SIZE(gfs2_stype))
1803
1804 static int gfs2_sbstats_seq_show(struct seq_file *seq, void *iter_ptr)
1805 {
1806         struct gfs2_glock_iter *gi = seq->private;
1807         struct gfs2_sbd *sdp = gi->sdp;
1808         unsigned index = gi->hash >> 3;
1809         unsigned subindex = gi->hash & 0x07;
1810         s64 value;
1811         int i;
1812
1813         if (index == 0 && subindex != 0)
1814                 return 0;
1815
1816         seq_printf(seq, "%-10s %8s:", gfs2_gltype[index],
1817                    (index == 0) ? "cpu": gfs2_stype[subindex]);
1818
1819         for_each_possible_cpu(i) {
1820                 const struct gfs2_pcpu_lkstats *lkstats = per_cpu_ptr(sdp->sd_lkstats, i);
1821                 if (index == 0) {
1822                         value = i;
1823                 } else {
1824                         value = lkstats->lkstats[index - 1].stats[subindex];
1825                 }
1826                 seq_printf(seq, " %15lld", (long long)value);
1827         }
1828         seq_putc(seq, '\n');
1829         return 0;
1830 }
1831
1832 int __init gfs2_glock_init(void)
1833 {
1834         unsigned i;
1835         for(i = 0; i < GFS2_GL_HASH_SIZE; i++) {
1836                 INIT_HLIST_BL_HEAD(&gl_hash_table[i]);
1837         }
1838
1839         glock_workqueue = alloc_workqueue("glock_workqueue", WQ_MEM_RECLAIM |
1840                                           WQ_HIGHPRI | WQ_FREEZABLE, 0);
1841         if (!glock_workqueue)
1842                 return -ENOMEM;
1843         gfs2_delete_workqueue = alloc_workqueue("delete_workqueue",
1844                                                 WQ_MEM_RECLAIM | WQ_FREEZABLE,
1845                                                 0);
1846         if (!gfs2_delete_workqueue) {
1847                 destroy_workqueue(glock_workqueue);
1848                 return -ENOMEM;
1849         }
1850
1851         register_shrinker(&glock_shrinker);
1852
1853         return 0;
1854 }
1855
1856 void gfs2_glock_exit(void)
1857 {
1858         unregister_shrinker(&glock_shrinker);
1859         destroy_workqueue(glock_workqueue);
1860         destroy_workqueue(gfs2_delete_workqueue);
1861 }
1862
1863 static inline struct gfs2_glock *glock_hash_chain(unsigned hash)
1864 {
1865         return hlist_bl_entry(hlist_bl_first_rcu(&gl_hash_table[hash]),
1866                               struct gfs2_glock, gl_list);
1867 }
1868
1869 static inline struct gfs2_glock *glock_hash_next(struct gfs2_glock *gl)
1870 {
1871         return hlist_bl_entry(rcu_dereference(gl->gl_list.next),
1872                               struct gfs2_glock, gl_list);
1873 }
1874
1875 static int gfs2_glock_iter_next(struct gfs2_glock_iter *gi)
1876 {
1877         struct gfs2_glock *gl;
1878
1879         do {
1880                 gl = gi->gl;
1881                 if (gl) {
1882                         gi->gl = glock_hash_next(gl);
1883                         gi->nhash++;
1884                 } else {
1885                         if (gi->hash >= GFS2_GL_HASH_SIZE) {
1886                                 rcu_read_unlock();
1887                                 return 1;
1888                         }
1889                         gi->gl = glock_hash_chain(gi->hash);
1890                         gi->nhash = 0;
1891                 }
1892                 while (gi->gl == NULL) {
1893                         gi->hash++;
1894                         if (gi->hash >= GFS2_GL_HASH_SIZE) {
1895                                 rcu_read_unlock();
1896                                 return 1;
1897                         }
1898                         gi->gl = glock_hash_chain(gi->hash);
1899                         gi->nhash = 0;
1900                 }
1901         /* Skip entries for other sb and dead entries */
1902         } while (gi->sdp != gi->gl->gl_sbd ||
1903                  __lockref_is_dead(&gi->gl->gl_lockref));
1904
1905         return 0;
1906 }
1907
1908 static void *gfs2_glock_seq_start(struct seq_file *seq, loff_t *pos)
1909 {
1910         struct gfs2_glock_iter *gi = seq->private;
1911         loff_t n = *pos;
1912
1913         if (gi->last_pos <= *pos)
1914                 n = gi->nhash + (*pos - gi->last_pos);
1915         else
1916                 gi->hash = 0;
1917
1918         gi->nhash = 0;
1919         rcu_read_lock();
1920
1921         do {
1922                 if (gfs2_glock_iter_next(gi))
1923                         return NULL;
1924         } while (n--);
1925
1926         gi->last_pos = *pos;
1927         return gi->gl;
1928 }
1929
1930 static void *gfs2_glock_seq_next(struct seq_file *seq, void *iter_ptr,
1931                                  loff_t *pos)
1932 {
1933         struct gfs2_glock_iter *gi = seq->private;
1934
1935         (*pos)++;
1936         gi->last_pos = *pos;
1937         if (gfs2_glock_iter_next(gi))
1938                 return NULL;
1939
1940         return gi->gl;
1941 }
1942
1943 static void gfs2_glock_seq_stop(struct seq_file *seq, void *iter_ptr)
1944 {
1945         struct gfs2_glock_iter *gi = seq->private;
1946
1947         if (gi->gl)
1948                 rcu_read_unlock();
1949         gi->gl = NULL;
1950 }
1951
1952 static int gfs2_glock_seq_show(struct seq_file *seq, void *iter_ptr)
1953 {
1954         return dump_glock(seq, iter_ptr);
1955 }
1956
1957 static void *gfs2_sbstats_seq_start(struct seq_file *seq, loff_t *pos)
1958 {
1959         struct gfs2_glock_iter *gi = seq->private;
1960
1961         gi->hash = *pos;
1962         if (*pos >= GFS2_NR_SBSTATS)
1963                 return NULL;
1964         preempt_disable();
1965         return SEQ_START_TOKEN;
1966 }
1967
1968 static void *gfs2_sbstats_seq_next(struct seq_file *seq, void *iter_ptr,
1969                                    loff_t *pos)
1970 {
1971         struct gfs2_glock_iter *gi = seq->private;
1972         (*pos)++;
1973         gi->hash++;
1974         if (gi->hash >= GFS2_NR_SBSTATS) {
1975                 preempt_enable();
1976                 return NULL;
1977         }
1978         return SEQ_START_TOKEN;
1979 }
1980
1981 static void gfs2_sbstats_seq_stop(struct seq_file *seq, void *iter_ptr)
1982 {
1983         preempt_enable();
1984 }
1985
1986 static const struct seq_operations gfs2_glock_seq_ops = {
1987         .start = gfs2_glock_seq_start,
1988         .next  = gfs2_glock_seq_next,
1989         .stop  = gfs2_glock_seq_stop,
1990         .show  = gfs2_glock_seq_show,
1991 };
1992
1993 static const struct seq_operations gfs2_glstats_seq_ops = {
1994         .start = gfs2_glock_seq_start,
1995         .next  = gfs2_glock_seq_next,
1996         .stop  = gfs2_glock_seq_stop,
1997         .show  = gfs2_glstats_seq_show,
1998 };
1999
2000 static const struct seq_operations gfs2_sbstats_seq_ops = {
2001         .start = gfs2_sbstats_seq_start,
2002         .next  = gfs2_sbstats_seq_next,
2003         .stop  = gfs2_sbstats_seq_stop,
2004         .show  = gfs2_sbstats_seq_show,
2005 };
2006
2007 #define GFS2_SEQ_GOODSIZE min(PAGE_SIZE << PAGE_ALLOC_COSTLY_ORDER, 65536UL)
2008
2009 static int gfs2_glocks_open(struct inode *inode, struct file *file)
2010 {
2011         int ret = seq_open_private(file, &gfs2_glock_seq_ops,
2012                                    sizeof(struct gfs2_glock_iter));
2013         if (ret == 0) {
2014                 struct seq_file *seq = file->private_data;
2015                 struct gfs2_glock_iter *gi = seq->private;
2016                 gi->sdp = inode->i_private;
2017                 seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
2018                 if (seq->buf)
2019                         seq->size = GFS2_SEQ_GOODSIZE;
2020         }
2021         return ret;
2022 }
2023
2024 static int gfs2_glstats_open(struct inode *inode, struct file *file)
2025 {
2026         int ret = seq_open_private(file, &gfs2_glstats_seq_ops,
2027                                    sizeof(struct gfs2_glock_iter));
2028         if (ret == 0) {
2029                 struct seq_file *seq = file->private_data;
2030                 struct gfs2_glock_iter *gi = seq->private;
2031                 gi->sdp = inode->i_private;
2032                 seq->buf = kmalloc(GFS2_SEQ_GOODSIZE, GFP_KERNEL | __GFP_NOWARN);
2033                 if (seq->buf)
2034                         seq->size = GFS2_SEQ_GOODSIZE;
2035         }
2036         return ret;
2037 }
2038
2039 static int gfs2_sbstats_open(struct inode *inode, struct file *file)
2040 {
2041         int ret = seq_open_private(file, &gfs2_sbstats_seq_ops,
2042                                    sizeof(struct gfs2_glock_iter));
2043         if (ret == 0) {
2044                 struct seq_file *seq = file->private_data;
2045                 struct gfs2_glock_iter *gi = seq->private;
2046                 gi->sdp = inode->i_private;
2047         }
2048         return ret;
2049 }
2050
2051 static const struct file_operations gfs2_glocks_fops = {
2052         .owner   = THIS_MODULE,
2053         .open    = gfs2_glocks_open,
2054         .read    = seq_read,
2055         .llseek  = seq_lseek,
2056         .release = seq_release_private,
2057 };
2058
2059 static const struct file_operations gfs2_glstats_fops = {
2060         .owner   = THIS_MODULE,
2061         .open    = gfs2_glstats_open,
2062         .read    = seq_read,
2063         .llseek  = seq_lseek,
2064         .release = seq_release_private,
2065 };
2066
2067 static const struct file_operations gfs2_sbstats_fops = {
2068         .owner   = THIS_MODULE,
2069         .open    = gfs2_sbstats_open,
2070         .read    = seq_read,
2071         .llseek  = seq_lseek,
2072         .release = seq_release_private,
2073 };
2074
2075 int gfs2_create_debugfs_file(struct gfs2_sbd *sdp)
2076 {
2077         sdp->debugfs_dir = debugfs_create_dir(sdp->sd_table_name, gfs2_root);
2078         if (!sdp->debugfs_dir)
2079                 return -ENOMEM;
2080         sdp->debugfs_dentry_glocks = debugfs_create_file("glocks",
2081                                                          S_IFREG | S_IRUGO,
2082                                                          sdp->debugfs_dir, sdp,
2083                                                          &gfs2_glocks_fops);
2084         if (!sdp->debugfs_dentry_glocks)
2085                 goto fail;
2086
2087         sdp->debugfs_dentry_glstats = debugfs_create_file("glstats",
2088                                                         S_IFREG | S_IRUGO,
2089                                                         sdp->debugfs_dir, sdp,
2090                                                         &gfs2_glstats_fops);
2091         if (!sdp->debugfs_dentry_glstats)
2092                 goto fail;
2093
2094         sdp->debugfs_dentry_sbstats = debugfs_create_file("sbstats",
2095                                                         S_IFREG | S_IRUGO,
2096                                                         sdp->debugfs_dir, sdp,
2097                                                         &gfs2_sbstats_fops);
2098         if (!sdp->debugfs_dentry_sbstats)
2099                 goto fail;
2100
2101         return 0;
2102 fail:
2103         gfs2_delete_debugfs_file(sdp);
2104         return -ENOMEM;
2105 }
2106
2107 void gfs2_delete_debugfs_file(struct gfs2_sbd *sdp)
2108 {
2109         if (sdp->debugfs_dir) {
2110                 if (sdp->debugfs_dentry_glocks) {
2111                         debugfs_remove(sdp->debugfs_dentry_glocks);
2112                         sdp->debugfs_dentry_glocks = NULL;
2113                 }
2114                 if (sdp->debugfs_dentry_glstats) {
2115                         debugfs_remove(sdp->debugfs_dentry_glstats);
2116                         sdp->debugfs_dentry_glstats = NULL;
2117                 }
2118                 if (sdp->debugfs_dentry_sbstats) {
2119                         debugfs_remove(sdp->debugfs_dentry_sbstats);
2120                         sdp->debugfs_dentry_sbstats = NULL;
2121                 }
2122                 debugfs_remove(sdp->debugfs_dir);
2123                 sdp->debugfs_dir = NULL;
2124         }
2125 }
2126
2127 int gfs2_register_debugfs(void)
2128 {
2129         gfs2_root = debugfs_create_dir("gfs2", NULL);
2130         return gfs2_root ? 0 : -ENOMEM;
2131 }
2132
2133 void gfs2_unregister_debugfs(void)
2134 {
2135         debugfs_remove(gfs2_root);
2136         gfs2_root = NULL;
2137 }