fs/btrfs/transaction.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/slab.h>
  21 #include <linux/sched.h>
  22 #include <linux/writeback.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/blkdev.h>
  25 #include "ctree.h"
  26 #include "disk-io.h"
  27 #include "transaction.h"
  28 #include "locking.h"
  29 #include "tree-log.h"
  30 #include "inode-map.h"
  31 #include "volumes.h"
  32
  33 #define BTRFS_ROOT_TRANS_TAG 0
  34
  35 void put_transaction(struct btrfs_transaction *transaction)
  36 {
  37         WARN_ON(atomic_read(&transaction->use_count) == 0);
  38         if (atomic_dec_and_test(&transaction->use_count)) {
  39                 BUG_ON(!list_empty(&transaction->list));
  40                 WARN_ON(transaction->delayed_refs.root.rb_node);
  41                 memset(transaction, 0, sizeof(*transaction));
  42                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  43         }
  44 }
  45
  46 static noinline void switch_commit_root(struct btrfs_root *root)
  47 {
  48         free_extent_buffer(root->commit_root);
  49         root->commit_root = btrfs_root_node(root);
  50 }
  51
  52 /*
  53  * either allocate a new transaction or hop into the existing one
  54  */
  55 static noinline int join_transaction(struct btrfs_root *root, int nofail)
  56 {
  57         struct btrfs_transaction *cur_trans;
  58         struct btrfs_fs_info *fs_info = root->fs_info;
  59
  60         spin_lock(&fs_info->trans_lock);
  61 loop:
  62         /* The file system has been taken offline. No new transactions. */
  63         if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
  64                 spin_unlock(&fs_info->trans_lock);
  65                 return -EROFS;
  66         }
  67
  68         if (fs_info->trans_no_join) {
  69                 if (!nofail) {
  70                         spin_unlock(&fs_info->trans_lock);
  71                         return -EBUSY;
  72                 }
  73         }
  74
  75         cur_trans = fs_info->running_transaction;
  76         if (cur_trans) {
  77                 if (cur_trans->aborted) {
  78                         spin_unlock(&fs_info->trans_lock);
  79                         return cur_trans->aborted;
  80                 }
  81                 atomic_inc(&cur_trans->use_count);
  82                 atomic_inc(&cur_trans->num_writers);
  83                 cur_trans->num_joined++;
  84                 spin_unlock(&fs_info->trans_lock);
  85                 return 0;
  86         }
  87         spin_unlock(&fs_info->trans_lock);
  88
  89         cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
  90         if (!cur_trans)
  91                 return -ENOMEM;
  92
  93         spin_lock(&fs_info->trans_lock);
  94         if (fs_info->running_transaction) {
  95                 /*
  96                  * someone started a transaction after we unlocked.  Make sure
  97                  * to redo the trans_no_join checks above
  98                  */
  99                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 100                 cur_trans = fs_info->running_transaction;
 101                 goto loop;
 102         } else if (fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 103                 spin_unlock(&fs_info->trans_lock);
 104                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 105                 return -EROFS;
 106         }
 107
 108         atomic_set(&cur_trans->num_writers, 1);
 109         cur_trans->num_joined = 0;
 110         init_waitqueue_head(&cur_trans->writer_wait);
 111         init_waitqueue_head(&cur_trans->commit_wait);
 112         cur_trans->in_commit = 0;
 113         cur_trans->blocked = 0;
 114         /*
 115          * One for this trans handle, one so it will live on until we
 116          * commit the transaction.
 117          */
 118         atomic_set(&cur_trans->use_count, 2);
 119         cur_trans->commit_done = 0;
 120         cur_trans->start_time = get_seconds();
 121
 122         cur_trans->delayed_refs.root = RB_ROOT;
 123         cur_trans->delayed_refs.num_entries = 0;
 124         cur_trans->delayed_refs.num_heads_ready = 0;
 125         cur_trans->delayed_refs.num_heads = 0;
 126         cur_trans->delayed_refs.flushing = 0;
 127         cur_trans->delayed_refs.run_delayed_start = 0;
 128
 129         /*
 130          * although the tree mod log is per file system and not per transaction,
 131          * the log must never go across transaction boundaries.
 132          */
 133         smp_mb();
 134         if (!list_empty(&fs_info->tree_mod_seq_list)) {
 135                 printk(KERN_ERR "btrfs: tree_mod_seq_list not empty when "
 136                         "creating a fresh transaction\n");
 137                 WARN_ON(1);
 138         }
 139         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log)) {
 140                 printk(KERN_ERR "btrfs: tree_mod_log rb tree not empty when "
 141                         "creating a fresh transaction\n");
 142                 WARN_ON(1);
 143         }
 144         atomic_set(&fs_info->tree_mod_seq, 0);
 145
 146         spin_lock_init(&cur_trans->commit_lock);
 147         spin_lock_init(&cur_trans->delayed_refs.lock);
 148
 149         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 150         list_add_tail(&cur_trans->list, &fs_info->trans_list);
 151         extent_io_tree_init(&cur_trans->dirty_pages,
 152                              fs_info->btree_inode->i_mapping);
 153         fs_info->generation++;
 154         cur_trans->transid = fs_info->generation;
 155         fs_info->running_transaction = cur_trans;
 156         cur_trans->aborted = 0;
 157         spin_unlock(&fs_info->trans_lock);
 158
 159         return 0;
 160 }
 161
 162 /*
 163  * this does all the record keeping required to make sure that a reference
 164  * counted root is properly recorded in a given transaction.  This is required
 165  * to make sure the old root from before we joined the transaction is deleted
 166  * when the transaction commits
 167  */
 168 static int record_root_in_trans(struct btrfs_trans_handle *trans,
 169                                struct btrfs_root *root)
 170 {
 171         if (root->ref_cows && root->last_trans < trans->transid) {
 172                 WARN_ON(root == root->fs_info->extent_root);
 173                 WARN_ON(root->commit_root != root->node);
 174
 175                 /*
 176                  * see below for in_trans_setup usage rules
 177                  * we have the reloc mutex held now, so there
 178                  * is only one writer in this function
 179                  */
 180                 root->in_trans_setup = 1;
 181
 182                 /* make sure readers find in_trans_setup before
 183                  * they find our root->last_trans update
 184                  */
 185                 smp_wmb();
 186
 187                 spin_lock(&root->fs_info->fs_roots_radix_lock);
 188                 if (root->last_trans == trans->transid) {
 189                         spin_unlock(&root->fs_info->fs_roots_radix_lock);
 190                         return 0;
 191                 }
 192                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 193                            (unsigned long)root->root_key.objectid,
 194                            BTRFS_ROOT_TRANS_TAG);
 195                 spin_unlock(&root->fs_info->fs_roots_radix_lock);
 196                 root->last_trans = trans->transid;
 197
 198                 /* this is pretty tricky.  We don't want to
 199                  * take the relocation lock in btrfs_record_root_in_trans
 200                  * unless we're really doing the first setup for this root in
 201                  * this transaction.
 202                  *
 203                  * Normally we'd use root->last_trans as a flag to decide
 204                  * if we want to take the expensive mutex.
 205                  *
 206                  * But, we have to set root->last_trans before we
 207                  * init the relocation root, otherwise, we trip over warnings
 208                  * in ctree.c.  The solution used here is to flag ourselves
 209                  * with root->in_trans_setup.  When this is 1, we're still
 210                  * fixing up the reloc trees and everyone must wait.
 211                  *
 212                  * When this is zero, they can trust root->last_trans and fly
 213                  * through btrfs_record_root_in_trans without having to take the
 214                  * lock.  smp_wmb() makes sure that all the writes above are
 215                  * done before we pop in the zero below
 216                  */
 217                 btrfs_init_reloc_root(trans, root);
 218                 smp_wmb();
 219                 root->in_trans_setup = 0;
 220         }
 221         return 0;
 222 }
 223
 224
 225 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 226                                struct btrfs_root *root)
 227 {
 228         if (!root->ref_cows)
 229                 return 0;
 230
 231         /*
 232          * see record_root_in_trans for comments about in_trans_setup usage
 233          * and barriers
 234          */
 235         smp_rmb();
 236         if (root->last_trans == trans->transid &&
 237             !root->in_trans_setup)
 238                 return 0;
 239
 240         mutex_lock(&root->fs_info->reloc_mutex);
 241         record_root_in_trans(trans, root);
 242         mutex_unlock(&root->fs_info->reloc_mutex);
 243
 244         return 0;
 245 }
 246
 247 /* wait for commit against the current transaction to become unblocked
 248  * when this is done, it is safe to start a new transaction, but the current
 249  * transaction might not be fully on disk.
 250  */
 251 static void wait_current_trans(struct btrfs_root *root)
 252 {
 253         struct btrfs_transaction *cur_trans;
 254
 255         spin_lock(&root->fs_info->trans_lock);
 256         cur_trans = root->fs_info->running_transaction;
 257         if (cur_trans && cur_trans->blocked) {
 258                 atomic_inc(&cur_trans->use_count);
 259                 spin_unlock(&root->fs_info->trans_lock);
 260
 261                 wait_event(root->fs_info->transaction_wait,
 262                            !cur_trans->blocked);
 263                 put_transaction(cur_trans);
 264         } else {
 265                 spin_unlock(&root->fs_info->trans_lock);
 266         }
 267 }
 268
 269 enum btrfs_trans_type {
 270         TRANS_START,
 271         TRANS_JOIN,
 272         TRANS_USERSPACE,
 273         TRANS_JOIN_NOLOCK,
 274 };
 275
 276 static int may_wait_transaction(struct btrfs_root *root, int type)
 277 {
 278         if (root->fs_info->log_root_recovering)
 279                 return 0;
 280
 281         if (type == TRANS_USERSPACE)
 282                 return 1;
 283
 284         if (type == TRANS_START &&
 285             !atomic_read(&root->fs_info->open_ioctl_trans))
 286                 return 1;
 287
 288         return 0;
 289 }
 290
 291 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 292                                                     u64 num_items, int type)
 293 {
 294         struct btrfs_trans_handle *h;
 295         struct btrfs_transaction *cur_trans;
 296         u64 num_bytes = 0;
 297         int ret;
 298         u64 qgroup_reserved = 0;
 299
 300         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
 301                 return ERR_PTR(-EROFS);
 302
 303         if (current->journal_info) {
 304                 WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK);
 305                 h = current->journal_info;
 306                 h->use_count++;
 307                 h->orig_rsv = h->block_rsv;
 308                 h->block_rsv = NULL;
 309                 goto got_it;
 310         }
 311
 312         /*
 313          * Do the reservation before we join the transaction so we can do all
 314          * the appropriate flushing if need be.
 315          */
 316         if (num_items > 0 && root != root->fs_info->chunk_root) {
 317                 if (root->fs_info->quota_enabled &&
 318                     is_fstree(root->root_key.objectid)) {
 319                         qgroup_reserved = num_items * root->leafsize;
 320                         ret = btrfs_qgroup_reserve(root, qgroup_reserved);
 321                         if (ret)
 322                                 return ERR_PTR(ret);
 323                 }
 324
 325                 num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
 326                 ret = btrfs_block_rsv_add(root,
 327                                           &root->fs_info->trans_block_rsv,
 328                                           num_bytes);
 329                 if (ret)
 330                         return ERR_PTR(ret);
 331         }
 332 again:
 333         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 334         if (!h)
 335                 return ERR_PTR(-ENOMEM);
 336
 337         if (may_wait_transaction(root, type))
 338                 wait_current_trans(root);
 339
 340         do {
 341                 ret = join_transaction(root, type == TRANS_JOIN_NOLOCK);
 342                 if (ret == -EBUSY)
 343                         wait_current_trans(root);
 344         } while (ret == -EBUSY);
 345
 346         if (ret < 0) {
 347                 kmem_cache_free(btrfs_trans_handle_cachep, h);
 348                 return ERR_PTR(ret);
 349         }
 350
 351         cur_trans = root->fs_info->running_transaction;
 352
 353         h->transid = cur_trans->transid;
 354         h->transaction = cur_trans;
 355         h->blocks_used = 0;
 356         h->bytes_reserved = 0;
 357         h->root = root;
 358         h->delayed_ref_updates = 0;
 359         h->use_count = 1;
 360         h->adding_csums = 0;
 361         h->block_rsv = NULL;
 362         h->orig_rsv = NULL;
 363         h->aborted = 0;
 364         h->qgroup_reserved = qgroup_reserved;
 365         h->delayed_ref_elem.seq = 0;
 366         INIT_LIST_HEAD(&h->qgroup_ref_list);
 367
 368         smp_mb();
 369         if (cur_trans->blocked && may_wait_transaction(root, type)) {
 370                 btrfs_commit_transaction(h, root);
 371                 goto again;
 372         }
 373
 374         if (num_bytes) {
 375                 trace_btrfs_space_reservation(root->fs_info, "transaction",
 376                                               h->transid, num_bytes, 1);
 377                 h->block_rsv = &root->fs_info->trans_block_rsv;
 378                 h->bytes_reserved = num_bytes;
 379         }
 380
 381 got_it:
 382         btrfs_record_root_in_trans(h, root);
 383
 384         if (!current->journal_info && type != TRANS_USERSPACE)
 385                 current->journal_info = h;
 386         return h;
 387 }
 388
 389 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 390                                                    int num_items)
 391 {
 392         return start_transaction(root, num_items, TRANS_START);
 393 }
 394 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 395 {
 396         return start_transaction(root, 0, TRANS_JOIN);
 397 }
 398
 399 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
 400 {
 401         return start_transaction(root, 0, TRANS_JOIN_NOLOCK);
 402 }
 403
 404 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 405 {
 406         return start_transaction(root, 0, TRANS_USERSPACE);
 407 }
 408
 409 /* wait for a transaction commit to be fully complete */
 410 static noinline void wait_for_commit(struct btrfs_root *root,
 411                                     struct btrfs_transaction *commit)
 412 {
 413         wait_event(commit->commit_wait, commit->commit_done);
 414 }
 415
 416 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 417 {
 418         struct btrfs_transaction *cur_trans = NULL, *t;
 419         int ret;
 420
 421         ret = 0;
 422         if (transid) {
 423                 if (transid <= root->fs_info->last_trans_committed)
 424                         goto out;
 425
 426                 /* find specified transaction */
 427                 spin_lock(&root->fs_info->trans_lock);
 428                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 429                         if (t->transid == transid) {
 430                                 cur_trans = t;
 431                                 atomic_inc(&cur_trans->use_count);
 432                                 break;
 433                         }
 434                         if (t->transid > transid)
 435                                 break;
 436                 }
 437                 spin_unlock(&root->fs_info->trans_lock);
 438                 ret = -EINVAL;
 439                 if (!cur_trans)
 440                         goto out;  /* bad transid */
 441         } else {
 442                 /* find newest transaction that is committing | committed */
 443                 spin_lock(&root->fs_info->trans_lock);
 444                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 445                                             list) {
 446                         if (t->in_commit) {
 447                                 if (t->commit_done)
 448                                         break;
 449                                 cur_trans = t;
 450                                 atomic_inc(&cur_trans->use_count);
 451                                 break;
 452                         }
 453                 }
 454                 spin_unlock(&root->fs_info->trans_lock);
 455                 if (!cur_trans)
 456                         goto out;  /* nothing committing|committed */
 457         }
 458
 459         wait_for_commit(root, cur_trans);
 460
 461         put_transaction(cur_trans);
 462         ret = 0;
 463 out:
 464         return ret;
 465 }
 466
 467 void btrfs_throttle(struct btrfs_root *root)
 468 {
 469         if (!atomic_read(&root->fs_info->open_ioctl_trans))
 470                 wait_current_trans(root);
 471 }
 472
 473 static int should_end_transaction(struct btrfs_trans_handle *trans,
 474                                   struct btrfs_root *root)
 475 {
 476         int ret;
 477
 478         ret = btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
 479         return ret ? 1 : 0;
 480 }
 481
 482 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 483                                  struct btrfs_root *root)
 484 {
 485         struct btrfs_transaction *cur_trans = trans->transaction;
 486         int updates;
 487         int err;
 488
 489         smp_mb();
 490         if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
 491                 return 1;
 492
 493         updates = trans->delayed_ref_updates;
 494         trans->delayed_ref_updates = 0;
 495         if (updates) {
 496                 err = btrfs_run_delayed_refs(trans, root, updates);
 497                 if (err) /* Error code will also eval true */
 498                         return err;
 499         }
 500
 501         return should_end_transaction(trans, root);
 502 }
 503
 504 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 505                           struct btrfs_root *root, int throttle, int lock)
 506 {
 507         struct btrfs_transaction *cur_trans = trans->transaction;
 508         struct btrfs_fs_info *info = root->fs_info;
 509         int count = 0;
 510         int err = 0;
 511
 512         if (--trans->use_count) {
 513                 trans->block_rsv = trans->orig_rsv;
 514                 return 0;
 515         }
 516
 517         /*
 518          * do the qgroup accounting as early as possible
 519          */
 520         err = btrfs_delayed_refs_qgroup_accounting(trans, info);
 521
 522         btrfs_trans_release_metadata(trans, root);
 523         trans->block_rsv = NULL;
 524         /*
 525          * the same root has to be passed to start_transaction and
 526          * end_transaction. Subvolume quota depends on this.
 527          */
 528         WARN_ON(trans->root != root);
 529
 530         if (trans->qgroup_reserved) {
 531                 btrfs_qgroup_free(root, trans->qgroup_reserved);
 532                 trans->qgroup_reserved = 0;
 533         }
 534
 535         while (count < 2) {
 536                 unsigned long cur = trans->delayed_ref_updates;
 537                 trans->delayed_ref_updates = 0;
 538                 if (cur &&
 539                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 540                         trans->delayed_ref_updates = 0;
 541                         btrfs_run_delayed_refs(trans, root, cur);
 542                 } else {
 543                         break;
 544                 }
 545                 count++;
 546         }
 547         btrfs_trans_release_metadata(trans, root);
 548         trans->block_rsv = NULL;
 549
 550         if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
 551             should_end_transaction(trans, root)) {
 552                 trans->transaction->blocked = 1;
 553                 smp_wmb();
 554         }
 555
 556         if (lock && cur_trans->blocked && !cur_trans->in_commit) {
 557                 if (throttle) {
 558                         /*
 559                          * We may race with somebody else here so end up having
 560                          * to call end_transaction on ourselves again, so inc
 561                          * our use_count.
 562                          */
 563                         trans->use_count++;
 564                         return btrfs_commit_transaction(trans, root);
 565                 } else {
 566                         wake_up_process(info->transaction_kthread);
 567                 }
 568         }
 569
 570         WARN_ON(cur_trans != info->running_transaction);
 571         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 572         atomic_dec(&cur_trans->num_writers);
 573
 574         smp_mb();
 575         if (waitqueue_active(&cur_trans->writer_wait))
 576                 wake_up(&cur_trans->writer_wait);
 577         put_transaction(cur_trans);
 578
 579         if (current->journal_info == trans)
 580                 current->journal_info = NULL;
 581
 582         if (throttle)
 583                 btrfs_run_delayed_iputs(root);
 584
 585         if (trans->aborted ||
 586             root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR) {
 587                 err = -EIO;
 588         }
 589         assert_qgroups_uptodate(trans);
 590
 591         memset(trans, 0, sizeof(*trans));
 592         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 593         return err;
 594 }
 595
 596 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 597                           struct btrfs_root *root)
 598 {
 599         int ret;
 600
 601         ret = __btrfs_end_transaction(trans, root, 0, 1);
 602         if (ret)
 603                 return ret;
 604         return 0;
 605 }
 606
 607 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 608                                    struct btrfs_root *root)
 609 {
 610         int ret;
 611
 612         ret = __btrfs_end_transaction(trans, root, 1, 1);
 613         if (ret)
 614                 return ret;
 615         return 0;
 616 }
 617
 618 int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
 619                                  struct btrfs_root *root)
 620 {
 621         int ret;
 622
 623         ret = __btrfs_end_transaction(trans, root, 0, 0);
 624         if (ret)
 625                 return ret;
 626         return 0;
 627 }
 628
 629 int btrfs_end_transaction_dmeta(struct btrfs_trans_handle *trans,
 630                                 struct btrfs_root *root)
 631 {
 632         return __btrfs_end_transaction(trans, root, 1, 1);
 633 }
 634
 635 /*
 636  * when btree blocks are allocated, they have some corresponding bits set for
 637  * them in one of two extent_io trees.  This is used to make sure all of
 638  * those extents are sent to disk but does not wait on them
 639  */
 640 int btrfs_write_marked_extents(struct btrfs_root *root,
 641                                struct extent_io_tree *dirty_pages, int mark)
 642 {
 643         int err = 0;
 644         int werr = 0;
 645         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 646         u64 start = 0;
 647         u64 end;
 648
 649         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 650                                       mark)) {
 651                 convert_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT, mark,
 652                                    GFP_NOFS);
 653                 err = filemap_fdatawrite_range(mapping, start, end);
 654                 if (err)
 655                         werr = err;
 656                 cond_resched();
 657                 start = end + 1;
 658         }
 659         if (err)
 660                 werr = err;
 661         return werr;
 662 }
 663
 664 /*
 665  * when btree blocks are allocated, they have some corresponding bits set for
 666  * them in one of two extent_io trees.  This is used to make sure all of
 667  * those extents are on disk for transaction or log commit.  We wait
 668  * on all the pages and clear them from the dirty pages state tree
 669  */
 670 int btrfs_wait_marked_extents(struct btrfs_root *root,
 671                               struct extent_io_tree *dirty_pages, int mark)
 672 {
 673         int err = 0;
 674         int werr = 0;
 675         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 676         u64 start = 0;
 677         u64 end;
 678
 679         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 680                                       EXTENT_NEED_WAIT)) {
 681                 clear_extent_bits(dirty_pages, start, end, EXTENT_NEED_WAIT, GFP_NOFS);
 682                 err = filemap_fdatawait_range(mapping, start, end);
 683                 if (err)
 684                         werr = err;
 685                 cond_resched();
 686                 start = end + 1;
 687         }
 688         if (err)
 689                 werr = err;
 690         return werr;
 691 }
 692
 693 /*
 694  * when btree blocks are allocated, they have some corresponding bits set for
 695  * them in one of two extent_io trees.  This is used to make sure all of
 696  * those extents are on disk for transaction or log commit
 697  */
 698 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 699                                 struct extent_io_tree *dirty_pages, int mark)
 700 {
 701         int ret;
 702         int ret2;
 703
 704         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 705         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 706
 707         if (ret)
 708                 return ret;
 709         if (ret2)
 710                 return ret2;
 711         return 0;
 712 }
 713
 714 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 715                                      struct btrfs_root *root)
 716 {
 717         if (!trans || !trans->transaction) {
 718                 struct inode *btree_inode;
 719                 btree_inode = root->fs_info->btree_inode;
 720                 return filemap_write_and_wait(btree_inode->i_mapping);
 721         }
 722         return btrfs_write_and_wait_marked_extents(root,
 723                                            &trans->transaction->dirty_pages,
 724                                            EXTENT_DIRTY);
 725 }
 726
 727 /*
 728  * this is used to update the root pointer in the tree of tree roots.
 729  *
 730  * But, in the case of the extent allocation tree, updating the root
 731  * pointer may allocate blocks which may change the root of the extent
 732  * allocation tree.
 733  *
 734  * So, this loops and repeats and makes sure the cowonly root didn't
 735  * change while the root pointer was being updated in the metadata.
 736  */
 737 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 738                                struct btrfs_root *root)
 739 {
 740         int ret;
 741         u64 old_root_bytenr;
 742         u64 old_root_used;
 743         struct btrfs_root *tree_root = root->fs_info->tree_root;
 744
 745         old_root_used = btrfs_root_used(&root->root_item);
 746         btrfs_write_dirty_block_groups(trans, root);
 747
 748         while (1) {
 749                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 750                 if (old_root_bytenr == root->node->start &&
 751                     old_root_used == btrfs_root_used(&root->root_item))
 752                         break;
 753
 754                 btrfs_set_root_node(&root->root_item, root->node);
 755                 ret = btrfs_update_root(trans, tree_root,
 756                                         &root->root_key,
 757                                         &root->root_item);
 758                 if (ret)
 759                         return ret;
 760
 761                 old_root_used = btrfs_root_used(&root->root_item);
 762                 ret = btrfs_write_dirty_block_groups(trans, root);
 763                 if (ret)
 764                         return ret;
 765         }
 766
 767         if (root != root->fs_info->extent_root)
 768                 switch_commit_root(root);
 769
 770         return 0;
 771 }
 772
 773 /*
 774  * update all the cowonly tree roots on disk
 775  *
 776  * The error handling in this function may not be obvious. Any of the
 777  * failures will cause the file system to go offline. We still need
 778  * to clean up the delayed refs.
 779  */
 780 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 781                                          struct btrfs_root *root)
 782 {
 783         struct btrfs_fs_info *fs_info = root->fs_info;
 784         struct list_head *next;
 785         struct extent_buffer *eb;
 786         int ret;
 787
 788         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 789         if (ret)
 790                 return ret;
 791
 792         eb = btrfs_lock_root_node(fs_info->tree_root);
 793         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
 794                               0, &eb);
 795         btrfs_tree_unlock(eb);
 796         free_extent_buffer(eb);
 797
 798         if (ret)
 799                 return ret;
 800
 801         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 802         if (ret)
 803                 return ret;
 804
 805         ret = btrfs_run_dev_stats(trans, root->fs_info);
 806         BUG_ON(ret);
 807
 808         ret = btrfs_run_qgroups(trans, root->fs_info);
 809         BUG_ON(ret);
 810
 811         /* run_qgroups might have added some more refs */
 812         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 813         BUG_ON(ret);
 814
 815         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 816                 next = fs_info->dirty_cowonly_roots.next;
 817                 list_del_init(next);
 818                 root = list_entry(next, struct btrfs_root, dirty_list);
 819
 820                 ret = update_cowonly_root(trans, root);
 821                 if (ret)
 822                         return ret;
 823         }
 824
 825         down_write(&fs_info->extent_commit_sem);
 826         switch_commit_root(fs_info->extent_root);
 827         up_write(&fs_info->extent_commit_sem);
 828
 829         return 0;
 830 }
 831
 832 /*
 833  * dead roots are old snapshots that need to be deleted.  This allocates
 834  * a dirty root struct and adds it into the list of dead roots that need to
 835  * be deleted
 836  */
 837 int btrfs_add_dead_root(struct btrfs_root *root)
 838 {
 839         spin_lock(&root->fs_info->trans_lock);
 840         list_add(&root->root_list, &root->fs_info->dead_roots);
 841         spin_unlock(&root->fs_info->trans_lock);
 842         return 0;
 843 }
 844
 845 /*
 846  * update all the cowonly tree roots on disk
 847  */
 848 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 849                                     struct btrfs_root *root)
 850 {
 851         struct btrfs_root *gang[8];
 852         struct btrfs_fs_info *fs_info = root->fs_info;
 853         int i;
 854         int ret;
 855         int err = 0;
 856
 857         spin_lock(&fs_info->fs_roots_radix_lock);
 858         while (1) {
 859                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
 860                                                  (void **)gang, 0,
 861                                                  ARRAY_SIZE(gang),
 862                                                  BTRFS_ROOT_TRANS_TAG);
 863                 if (ret == 0)
 864                         break;
 865                 for (i = 0; i < ret; i++) {
 866                         root = gang[i];
 867                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
 868                                         (unsigned long)root->root_key.objectid,
 869                                         BTRFS_ROOT_TRANS_TAG);
 870                         spin_unlock(&fs_info->fs_roots_radix_lock);
 871
 872                         btrfs_free_log(trans, root);
 873                         btrfs_update_reloc_root(trans, root);
 874                         btrfs_orphan_commit_root(trans, root);
 875
 876                         btrfs_save_ino_cache(root, trans);
 877
 878                         /* see comments in should_cow_block() */
 879                         root->force_cow = 0;
 880                         smp_wmb();
 881
 882                         if (root->commit_root != root->node) {
 883                                 mutex_lock(&root->fs_commit_mutex);
 884                                 switch_commit_root(root);
 885                                 btrfs_unpin_free_ino(root);
 886                                 mutex_unlock(&root->fs_commit_mutex);
 887
 888                                 btrfs_set_root_node(&root->root_item,
 889                                                     root->node);
 890                         }
 891
 892                         err = btrfs_update_root(trans, fs_info->tree_root,
 893                                                 &root->root_key,
 894                                                 &root->root_item);
 895                         spin_lock(&fs_info->fs_roots_radix_lock);
 896                         if (err)
 897                                 break;
 898                 }
 899         }
 900         spin_unlock(&fs_info->fs_roots_radix_lock);
 901         return err;
 902 }
 903
 904 /*
 905  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
 906  * otherwise every leaf in the btree is read and defragged.
 907  */
 908 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 909 {
 910         struct btrfs_fs_info *info = root->fs_info;
 911         struct btrfs_trans_handle *trans;
 912         int ret;
 913         unsigned long nr;
 914
 915         if (xchg(&root->defrag_running, 1))
 916                 return 0;
 917
 918         while (1) {
 919                 trans = btrfs_start_transaction(root, 0);
 920                 if (IS_ERR(trans))
 921                         return PTR_ERR(trans);
 922
 923                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 924
 925                 nr = trans->blocks_used;
 926                 btrfs_end_transaction(trans, root);
 927                 btrfs_btree_balance_dirty(info->tree_root, nr);
 928                 cond_resched();
 929
 930                 if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
 931                         break;
 932         }
 933         root->defrag_running = 0;
 934         return ret;
 935 }
 936
 937 /*
 938  * new snapshots need to be created at a very specific time in the
 939  * transaction commit.  This does the actual creation
 940  */
 941 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 942                                    struct btrfs_fs_info *fs_info,
 943                                    struct btrfs_pending_snapshot *pending)
 944 {
 945         struct btrfs_key key;
 946         struct btrfs_root_item *new_root_item;
 947         struct btrfs_root *tree_root = fs_info->tree_root;
 948         struct btrfs_root *root = pending->root;
 949         struct btrfs_root *parent_root;
 950         struct btrfs_block_rsv *rsv;
 951         struct inode *parent_inode;
 952         struct dentry *parent;
 953         struct dentry *dentry;
 954         struct extent_buffer *tmp;
 955         struct extent_buffer *old;
 956         int ret;
 957         u64 to_reserve = 0;
 958         u64 index = 0;
 959         u64 objectid;
 960         u64 root_flags;
 961
 962         rsv = trans->block_rsv;
 963
 964         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 965         if (!new_root_item) {
 966                 ret = pending->error = -ENOMEM;
 967                 goto fail;
 968         }
 969
 970         ret = btrfs_find_free_objectid(tree_root, &objectid);
 971         if (ret) {
 972                 pending->error = ret;
 973                 goto fail;
 974         }
 975
 976         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
 977
 978         if (to_reserve > 0) {
 979                 ret = btrfs_block_rsv_add_noflush(root, &pending->block_rsv,
 980                                                   to_reserve);
 981                 if (ret) {
 982                         pending->error = ret;
 983                         goto fail;
 984                 }
 985         }
 986
 987         ret = btrfs_qgroup_inherit(trans, fs_info, root->root_key.objectid,
 988                                    objectid, pending->inherit);
 989         kfree(pending->inherit);
 990         if (ret) {
 991                 pending->error = ret;
 992                 goto fail;
 993         }
 994
 995         key.objectid = objectid;
 996         key.offset = (u64)-1;
 997         key.type = BTRFS_ROOT_ITEM_KEY;
 998
 999         trans->block_rsv = &pending->block_rsv;
1000
1001         dentry = pending->dentry;
1002         parent = dget_parent(dentry);
1003         parent_inode = parent->d_inode;
1004         parent_root = BTRFS_I(parent_inode)->root;
1005         record_root_in_trans(trans, parent_root);
1006
1007         /*
1008          * insert the directory item
1009          */
1010         ret = btrfs_set_inode_index(parent_inode, &index);
1011         BUG_ON(ret); /* -ENOMEM */
1012         ret = btrfs_insert_dir_item(trans, parent_root,
1013                                 dentry->d_name.name, dentry->d_name.len,
1014                                 parent_inode, &key,
1015                                 BTRFS_FT_DIR, index);
1016         if (ret == -EEXIST) {
1017                 pending->error = -EEXIST;
1018                 dput(parent);
1019                 goto fail;
1020         } else if (ret) {
1021                 goto abort_trans_dput;
1022         }
1023
1024         btrfs_i_size_write(parent_inode, parent_inode->i_size +
1025                                          dentry->d_name.len * 2);
1026         ret = btrfs_update_inode(trans, parent_root, parent_inode);
1027         if (ret)
1028                 goto abort_trans_dput;
1029
1030         /*
1031          * pull in the delayed directory update
1032          * and the delayed inode item
1033          * otherwise we corrupt the FS during
1034          * snapshot
1035          */
1036         ret = btrfs_run_delayed_items(trans, root);
1037         if (ret) { /* Transaction aborted */
1038                 dput(parent);
1039                 goto fail;
1040         }
1041
1042         record_root_in_trans(trans, root);
1043         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1044         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1045         btrfs_check_and_init_root_item(new_root_item);
1046
1047         root_flags = btrfs_root_flags(new_root_item);
1048         if (pending->readonly)
1049                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1050         else
1051                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1052         btrfs_set_root_flags(new_root_item, root_flags);
1053
1054         old = btrfs_lock_root_node(root);
1055         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1056         if (ret) {
1057                 btrfs_tree_unlock(old);
1058                 free_extent_buffer(old);
1059                 goto abort_trans_dput;
1060         }
1061
1062         btrfs_set_lock_blocking(old);
1063
1064         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1065         /* clean up in any case */
1066         btrfs_tree_unlock(old);
1067         free_extent_buffer(old);
1068         if (ret)
1069                 goto abort_trans_dput;
1070
1071         /* see comments in should_cow_block() */
1072         root->force_cow = 1;
1073         smp_wmb();
1074
1075         btrfs_set_root_node(new_root_item, tmp);
1076         /* record when the snapshot was created in key.offset */
1077         key.offset = trans->transid;
1078         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1079         btrfs_tree_unlock(tmp);
1080         free_extent_buffer(tmp);
1081         if (ret)
1082                 goto abort_trans_dput;
1083
1084         /*
1085          * insert root back/forward references
1086          */
1087         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1088                                  parent_root->root_key.objectid,
1089                                  btrfs_ino(parent_inode), index,
1090                                  dentry->d_name.name, dentry->d_name.len);
1091         dput(parent);
1092         if (ret)
1093                 goto fail;
1094
1095         key.offset = (u64)-1;
1096         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1097         if (IS_ERR(pending->snap)) {
1098                 ret = PTR_ERR(pending->snap);
1099                 goto abort_trans;
1100         }
1101
1102         ret = btrfs_reloc_post_snapshot(trans, pending);
1103         if (ret)
1104                 goto abort_trans;
1105         ret = 0;
1106 fail:
1107         kfree(new_root_item);
1108         trans->block_rsv = rsv;
1109         btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
1110         return ret;
1111
1112 abort_trans_dput:
1113         dput(parent);
1114 abort_trans:
1115         btrfs_abort_transaction(trans, root, ret);
1116         goto fail;
1117 }
1118
1119 /*
1120  * create all the snapshots we've scheduled for creation
1121  */
1122 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1123                                              struct btrfs_fs_info *fs_info)
1124 {
1125         struct btrfs_pending_snapshot *pending;
1126         struct list_head *head = &trans->transaction->pending_snapshots;
1127
1128         list_for_each_entry(pending, head, list)
1129                 create_pending_snapshot(trans, fs_info, pending);
1130         return 0;
1131 }
1132
1133 static void update_super_roots(struct btrfs_root *root)
1134 {
1135         struct btrfs_root_item *root_item;
1136         struct btrfs_super_block *super;
1137
1138         super = root->fs_info->super_copy;
1139
1140         root_item = &root->fs_info->chunk_root->root_item;
1141         super->chunk_root = root_item->bytenr;
1142         super->chunk_root_generation = root_item->generation;
1143         super->chunk_root_level = root_item->level;
1144
1145         root_item = &root->fs_info->tree_root->root_item;
1146         super->root = root_item->bytenr;
1147         super->generation = root_item->generation;
1148         super->root_level = root_item->level;
1149         if (btrfs_test_opt(root, SPACE_CACHE))
1150                 super->cache_generation = root_item->generation;
1151 }
1152
1153 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1154 {
1155         int ret = 0;
1156         spin_lock(&info->trans_lock);
1157         if (info->running_transaction)
1158                 ret = info->running_transaction->in_commit;
1159         spin_unlock(&info->trans_lock);
1160         return ret;
1161 }
1162
1163 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1164 {
1165         int ret = 0;
1166         spin_lock(&info->trans_lock);
1167         if (info->running_transaction)
1168                 ret = info->running_transaction->blocked;
1169         spin_unlock(&info->trans_lock);
1170         return ret;
1171 }
1172
1173 /*
1174  * wait for the current transaction commit to start and block subsequent
1175  * transaction joins
1176  */
1177 static void wait_current_trans_commit_start(struct btrfs_root *root,
1178                                             struct btrfs_transaction *trans)
1179 {
1180         wait_event(root->fs_info->transaction_blocked_wait, trans->in_commit);
1181 }
1182
1183 /*
1184  * wait for the current transaction to start and then become unblocked.
1185  * caller holds ref.
1186  */
1187 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1188                                          struct btrfs_transaction *trans)
1189 {
1190         wait_event(root->fs_info->transaction_wait,
1191                    trans->commit_done || (trans->in_commit && !trans->blocked));
1192 }
1193
1194 /*
1195  * commit transactions asynchronously. once btrfs_commit_transaction_async
1196  * returns, any subsequent transaction will not be allowed to join.
1197  */
1198 struct btrfs_async_commit {
1199         struct btrfs_trans_handle *newtrans;
1200         struct btrfs_root *root;
1201         struct delayed_work work;
1202 };
1203
1204 static void do_async_commit(struct work_struct *work)
1205 {
1206         struct btrfs_async_commit *ac =
1207                 container_of(work, struct btrfs_async_commit, work.work);
1208
1209         btrfs_commit_transaction(ac->newtrans, ac->root);
1210         kfree(ac);
1211 }
1212
1213 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1214                                    struct btrfs_root *root,
1215                                    int wait_for_unblock)
1216 {
1217         struct btrfs_async_commit *ac;
1218         struct btrfs_transaction *cur_trans;
1219
1220         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1221         if (!ac)
1222                 return -ENOMEM;
1223
1224         INIT_DELAYED_WORK(&ac->work, do_async_commit);
1225         ac->root = root;
1226         ac->newtrans = btrfs_join_transaction(root);
1227         if (IS_ERR(ac->newtrans)) {
1228                 int err = PTR_ERR(ac->newtrans);
1229                 kfree(ac);
1230                 return err;
1231         }
1232
1233         /* take transaction reference */
1234         cur_trans = trans->transaction;
1235         atomic_inc(&cur_trans->use_count);
1236
1237         btrfs_end_transaction(trans, root);
1238         schedule_delayed_work(&ac->work, 0);
1239
1240         /* wait for transaction to start and unblock */
1241         if (wait_for_unblock)
1242                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1243         else
1244                 wait_current_trans_commit_start(root, cur_trans);
1245
1246         if (current->journal_info == trans)
1247                 current->journal_info = NULL;
1248
1249         put_transaction(cur_trans);
1250         return 0;
1251 }
1252
1253
1254 static void cleanup_transaction(struct btrfs_trans_handle *trans,
1255                                 struct btrfs_root *root, int err)
1256 {
1257         struct btrfs_transaction *cur_trans = trans->transaction;
1258
1259         WARN_ON(trans->use_count > 1);
1260
1261         btrfs_abort_transaction(trans, root, err);
1262
1263         spin_lock(&root->fs_info->trans_lock);
1264         list_del_init(&cur_trans->list);
1265         if (cur_trans == root->fs_info->running_transaction) {
1266                 root->fs_info->running_transaction = NULL;
1267                 root->fs_info->trans_no_join = 0;
1268         }
1269         spin_unlock(&root->fs_info->trans_lock);
1270
1271         btrfs_cleanup_one_transaction(trans->transaction, root);
1272
1273         put_transaction(cur_trans);
1274         put_transaction(cur_trans);
1275
1276         trace_btrfs_transaction_commit(root);
1277
1278         btrfs_scrub_continue(root);
1279
1280         if (current->journal_info == trans)
1281                 current->journal_info = NULL;
1282
1283         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1284 }
1285
1286 /*
1287  * btrfs_transaction state sequence:
1288  *    in_commit = 0, blocked = 0  (initial)
1289  *    in_commit = 1, blocked = 1
1290  *    blocked = 0
1291  *    commit_done = 1
1292  */
1293 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1294                              struct btrfs_root *root)
1295 {
1296         unsigned long joined = 0;
1297         struct btrfs_transaction *cur_trans = trans->transaction;
1298         struct btrfs_transaction *prev_trans = NULL;
1299         DEFINE_WAIT(wait);
1300         int ret = -EIO;
1301         int should_grow = 0;
1302         unsigned long now = get_seconds();
1303         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1304
1305         btrfs_run_ordered_operations(root, 0);
1306
1307         if (cur_trans->aborted)
1308                 goto cleanup_transaction;
1309
1310         /* make a pass through all the delayed refs we have so far
1311          * any runnings procs may add more while we are here
1312          */
1313         ret = btrfs_run_delayed_refs(trans, root, 0);
1314         if (ret)
1315                 goto cleanup_transaction;
1316
1317         btrfs_trans_release_metadata(trans, root);
1318         trans->block_rsv = NULL;
1319
1320         cur_trans = trans->transaction;
1321
1322         /*
1323          * set the flushing flag so procs in this transaction have to
1324          * start sending their work down.
1325          */
1326         cur_trans->delayed_refs.flushing = 1;
1327
1328         ret = btrfs_run_delayed_refs(trans, root, 0);
1329         if (ret)
1330                 goto cleanup_transaction;
1331
1332         spin_lock(&cur_trans->commit_lock);
1333         if (cur_trans->in_commit) {
1334                 spin_unlock(&cur_trans->commit_lock);
1335                 atomic_inc(&cur_trans->use_count);
1336                 ret = btrfs_end_transaction(trans, root);
1337
1338                 wait_for_commit(root, cur_trans);
1339
1340                 put_transaction(cur_trans);
1341
1342                 return ret;
1343         }
1344
1345         trans->transaction->in_commit = 1;
1346         trans->transaction->blocked = 1;
1347         spin_unlock(&cur_trans->commit_lock);
1348         wake_up(&root->fs_info->transaction_blocked_wait);
1349
1350         spin_lock(&root->fs_info->trans_lock);
1351         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1352                 prev_trans = list_entry(cur_trans->list.prev,
1353                                         struct btrfs_transaction, list);
1354                 if (!prev_trans->commit_done) {
1355                         atomic_inc(&prev_trans->use_count);
1356                         spin_unlock(&root->fs_info->trans_lock);
1357
1358                         wait_for_commit(root, prev_trans);
1359
1360                         put_transaction(prev_trans);
1361                 } else {
1362                         spin_unlock(&root->fs_info->trans_lock);
1363                 }
1364         } else {
1365                 spin_unlock(&root->fs_info->trans_lock);
1366         }
1367
1368         if (!btrfs_test_opt(root, SSD) &&
1369             (now < cur_trans->start_time || now - cur_trans->start_time < 1))
1370                 should_grow = 1;
1371
1372         do {
1373                 int snap_pending = 0;
1374
1375                 joined = cur_trans->num_joined;
1376                 if (!list_empty(&trans->transaction->pending_snapshots))
1377                         snap_pending = 1;
1378
1379                 WARN_ON(cur_trans != trans->transaction);
1380
1381                 if (flush_on_commit || snap_pending) {
1382                         btrfs_start_delalloc_inodes(root, 1);
1383                         btrfs_wait_ordered_extents(root, 0, 1);
1384                 }
1385
1386                 ret = btrfs_run_delayed_items(trans, root);
1387                 if (ret)
1388                         goto cleanup_transaction;
1389
1390                 /*
1391                  * running the delayed items may have added new refs. account
1392                  * them now so that they hinder processing of more delayed refs
1393                  * as little as possible.
1394                  */
1395                 btrfs_delayed_refs_qgroup_accounting(trans, root->fs_info);
1396
1397                 /*
1398                  * rename don't use btrfs_join_transaction, so, once we
1399                  * set the transaction to blocked above, we aren't going
1400                  * to get any new ordered operations.  We can safely run
1401                  * it here and no for sure that nothing new will be added
1402                  * to the list
1403                  */
1404                 btrfs_run_ordered_operations(root, 1);
1405
1406                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1407                                 TASK_UNINTERRUPTIBLE);
1408
1409                 if (atomic_read(&cur_trans->num_writers) > 1)
1410                         schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1411                 else if (should_grow)
1412                         schedule_timeout(1);
1413
1414                 finish_wait(&cur_trans->writer_wait, &wait);
1415         } while (atomic_read(&cur_trans->num_writers) > 1 ||
1416                  (should_grow && cur_trans->num_joined != joined));
1417
1418         /*
1419          * Ok now we need to make sure to block out any other joins while we
1420          * commit the transaction.  We could have started a join before setting
1421          * no_join so make sure to wait for num_writers to == 1 again.
1422          */
1423         spin_lock(&root->fs_info->trans_lock);
1424         root->fs_info->trans_no_join = 1;
1425         spin_unlock(&root->fs_info->trans_lock);
1426         wait_event(cur_trans->writer_wait,
1427                    atomic_read(&cur_trans->num_writers) == 1);
1428
1429         /*
1430          * the reloc mutex makes sure that we stop
1431          * the balancing code from coming in and moving
1432          * extents around in the middle of the commit
1433          */
1434         mutex_lock(&root->fs_info->reloc_mutex);
1435
1436         ret = btrfs_run_delayed_items(trans, root);
1437         if (ret) {
1438                 mutex_unlock(&root->fs_info->reloc_mutex);
1439                 goto cleanup_transaction;
1440         }
1441
1442         ret = create_pending_snapshots(trans, root->fs_info);
1443         if (ret) {
1444                 mutex_unlock(&root->fs_info->reloc_mutex);
1445                 goto cleanup_transaction;
1446         }
1447
1448         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1449         if (ret) {
1450                 mutex_unlock(&root->fs_info->reloc_mutex);
1451                 goto cleanup_transaction;
1452         }
1453
1454         /*
1455          * make sure none of the code above managed to slip in a
1456          * delayed item
1457          */
1458         btrfs_assert_delayed_root_empty(root);
1459
1460         WARN_ON(cur_trans != trans->transaction);
1461
1462         btrfs_scrub_pause(root);
1463         /* btrfs_commit_tree_roots is responsible for getting the
1464          * various roots consistent with each other.  Every pointer
1465          * in the tree of tree roots has to point to the most up to date
1466          * root for every subvolume and other tree.  So, we have to keep
1467          * the tree logging code from jumping in and changing any
1468          * of the trees.
1469          *
1470          * At this point in the commit, there can't be any tree-log
1471          * writers, but a little lower down we drop the trans mutex
1472          * and let new people in.  By holding the tree_log_mutex
1473          * from now until after the super is written, we avoid races
1474          * with the tree-log code.
1475          */
1476         mutex_lock(&root->fs_info->tree_log_mutex);
1477
1478         ret = commit_fs_roots(trans, root);
1479         if (ret) {
1480                 mutex_unlock(&root->fs_info->tree_log_mutex);
1481                 mutex_unlock(&root->fs_info->reloc_mutex);
1482                 goto cleanup_transaction;
1483         }
1484
1485         /* commit_fs_roots gets rid of all the tree log roots, it is now
1486          * safe to free the root of tree log roots
1487          */
1488         btrfs_free_log_root_tree(trans, root->fs_info);
1489
1490         ret = commit_cowonly_roots(trans, root);
1491         if (ret) {
1492                 mutex_unlock(&root->fs_info->tree_log_mutex);
1493                 mutex_unlock(&root->fs_info->reloc_mutex);
1494                 goto cleanup_transaction;
1495         }
1496
1497         btrfs_prepare_extent_commit(trans, root);
1498
1499         cur_trans = root->fs_info->running_transaction;
1500
1501         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1502                             root->fs_info->tree_root->node);
1503         switch_commit_root(root->fs_info->tree_root);
1504
1505         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1506                             root->fs_info->chunk_root->node);
1507         switch_commit_root(root->fs_info->chunk_root);
1508
1509         assert_qgroups_uptodate(trans);
1510         update_super_roots(root);
1511
1512         if (!root->fs_info->log_root_recovering) {
1513                 btrfs_set_super_log_root(root->fs_info->super_copy, 0);
1514                 btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
1515         }
1516
1517         memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
1518                sizeof(*root->fs_info->super_copy));
1519
1520         trans->transaction->blocked = 0;
1521         spin_lock(&root->fs_info->trans_lock);
1522         root->fs_info->running_transaction = NULL;
1523         root->fs_info->trans_no_join = 0;
1524         spin_unlock(&root->fs_info->trans_lock);
1525         mutex_unlock(&root->fs_info->reloc_mutex);
1526
1527         wake_up(&root->fs_info->transaction_wait);
1528
1529         ret = btrfs_write_and_wait_transaction(trans, root);
1530         if (ret) {
1531                 btrfs_error(root->fs_info, ret,
1532                             "Error while writing out transaction.");
1533                 mutex_unlock(&root->fs_info->tree_log_mutex);
1534                 goto cleanup_transaction;
1535         }
1536
1537         ret = write_ctree_super(trans, root, 0);
1538         if (ret) {
1539                 mutex_unlock(&root->fs_info->tree_log_mutex);
1540                 goto cleanup_transaction;
1541         }
1542
1543         /*
1544          * the super is written, we can safely allow the tree-loggers
1545          * to go about their business
1546          */
1547         mutex_unlock(&root->fs_info->tree_log_mutex);
1548
1549         btrfs_finish_extent_commit(trans, root);
1550
1551         cur_trans->commit_done = 1;
1552
1553         root->fs_info->last_trans_committed = cur_trans->transid;
1554
1555         wake_up(&cur_trans->commit_wait);
1556
1557         spin_lock(&root->fs_info->trans_lock);
1558         list_del_init(&cur_trans->list);
1559         spin_unlock(&root->fs_info->trans_lock);
1560
1561         put_transaction(cur_trans);
1562         put_transaction(cur_trans);
1563
1564         trace_btrfs_transaction_commit(root);
1565
1566         btrfs_scrub_continue(root);
1567
1568         if (current->journal_info == trans)
1569                 current->journal_info = NULL;
1570
1571         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1572
1573         if (current != root->fs_info->transaction_kthread)
1574                 btrfs_run_delayed_iputs(root);
1575
1576         return ret;
1577
1578 cleanup_transaction:
1579         btrfs_trans_release_metadata(trans, root);
1580         trans->block_rsv = NULL;
1581         btrfs_printk(root->fs_info, "Skipping commit of aborted transaction.\n");
1582 //      WARN_ON(1);
1583         if (current->journal_info == trans)
1584                 current->journal_info = NULL;
1585         cleanup_transaction(trans, root, ret);
1586
1587         return ret;
1588 }
1589
1590 /*
1591  * interface function to delete all the snapshots we have scheduled for deletion
1592  */
1593 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1594 {
1595         LIST_HEAD(list);
1596         struct btrfs_fs_info *fs_info = root->fs_info;
1597
1598         spin_lock(&fs_info->trans_lock);
1599         list_splice_init(&fs_info->dead_roots, &list);
1600         spin_unlock(&fs_info->trans_lock);
1601
1602         while (!list_empty(&list)) {
1603                 int ret;
1604
1605                 root = list_entry(list.next, struct btrfs_root, root_list);
1606                 list_del(&root->root_list);
1607
1608                 btrfs_kill_all_delayed_nodes(root);
1609
1610                 if (btrfs_header_backref_rev(root->node) <
1611                     BTRFS_MIXED_BACKREF_REV)
1612                         ret = btrfs_drop_snapshot(root, NULL, 0, 0);
1613                 else
1614                         ret =btrfs_drop_snapshot(root, NULL, 1, 0);
1615                 BUG_ON(ret < 0);
1616         }
1617         return 0;
1618 }