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
  32 #define BTRFS_ROOT_TRANS_TAG 0
  33
  34 static noinline void put_transaction(struct btrfs_transaction *transaction)
  35 {
  36         WARN_ON(atomic_read(&transaction->use_count) == 0);
  37         if (atomic_dec_and_test(&transaction->use_count)) {
  38                 memset(transaction, 0, sizeof(*transaction));
  39                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  40         }
  41 }
  42
  43 static noinline void switch_commit_root(struct btrfs_root *root)
  44 {
  45         free_extent_buffer(root->commit_root);
  46         root->commit_root = btrfs_root_node(root);
  47 }
  48
  49 /*
  50  * either allocate a new transaction or hop into the existing one
  51  */
  52 static noinline int join_transaction(struct btrfs_root *root)
  53 {
  54         struct btrfs_transaction *cur_trans;
  55         cur_trans = root->fs_info->running_transaction;
  56         if (!cur_trans) {
  57                 cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
  58                                              GFP_NOFS);
  59                 if (!cur_trans)
  60                         return -ENOMEM;
  61                 root->fs_info->generation++;
  62                 atomic_set(&cur_trans->num_writers, 1);
  63                 cur_trans->num_joined = 0;
  64                 cur_trans->transid = root->fs_info->generation;
  65                 init_waitqueue_head(&cur_trans->writer_wait);
  66                 init_waitqueue_head(&cur_trans->commit_wait);
  67                 cur_trans->in_commit = 0;
  68                 cur_trans->blocked = 0;
  69                 atomic_set(&cur_trans->use_count, 1);
  70                 cur_trans->commit_done = 0;
  71                 cur_trans->start_time = get_seconds();
  72
  73                 cur_trans->delayed_refs.root = RB_ROOT;
  74                 cur_trans->delayed_refs.num_entries = 0;
  75                 cur_trans->delayed_refs.num_heads_ready = 0;
  76                 cur_trans->delayed_refs.num_heads = 0;
  77                 cur_trans->delayed_refs.flushing = 0;
  78                 cur_trans->delayed_refs.run_delayed_start = 0;
  79                 spin_lock_init(&cur_trans->delayed_refs.lock);
  80
  81                 INIT_LIST_HEAD(&cur_trans->pending_snapshots);
  82                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
  83                 extent_io_tree_init(&cur_trans->dirty_pages,
  84                                      root->fs_info->btree_inode->i_mapping);
  85                 spin_lock(&root->fs_info->new_trans_lock);
  86                 root->fs_info->running_transaction = cur_trans;
  87                 spin_unlock(&root->fs_info->new_trans_lock);
  88         } else {
  89                 atomic_inc(&cur_trans->num_writers);
  90                 cur_trans->num_joined++;
  91         }
  92
  93         return 0;
  94 }
  95
  96 /*
  97  * this does all the record keeping required to make sure that a reference
  98  * counted root is properly recorded in a given transaction.  This is required
  99  * to make sure the old root from before we joined the transaction is deleted
 100  * when the transaction commits
 101  */
 102 static noinline int record_root_in_trans(struct btrfs_trans_handle *trans,
 103                                          struct btrfs_root *root)
 104 {
 105         if (root->ref_cows && root->last_trans < trans->transid) {
 106                 WARN_ON(root == root->fs_info->extent_root);
 107                 WARN_ON(root->commit_root != root->node);
 108
 109                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 110                            (unsigned long)root->root_key.objectid,
 111                            BTRFS_ROOT_TRANS_TAG);
 112                 root->last_trans = trans->transid;
 113                 btrfs_init_reloc_root(trans, root);
 114         }
 115         return 0;
 116 }
 117
 118 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 119                                struct btrfs_root *root)
 120 {
 121         if (!root->ref_cows)
 122                 return 0;
 123
 124         mutex_lock(&root->fs_info->trans_mutex);
 125         if (root->last_trans == trans->transid) {
 126                 mutex_unlock(&root->fs_info->trans_mutex);
 127                 return 0;
 128         }
 129
 130         record_root_in_trans(trans, root);
 131         mutex_unlock(&root->fs_info->trans_mutex);
 132         return 0;
 133 }
 134
 135 /* wait for commit against the current transaction to become unblocked
 136  * when this is done, it is safe to start a new transaction, but the current
 137  * transaction might not be fully on disk.
 138  */
 139 static void wait_current_trans(struct btrfs_root *root)
 140 {
 141         struct btrfs_transaction *cur_trans;
 142
 143         cur_trans = root->fs_info->running_transaction;
 144         if (cur_trans && cur_trans->blocked) {
 145                 DEFINE_WAIT(wait);
 146                 atomic_inc(&cur_trans->use_count);
 147                 while (1) {
 148                         prepare_to_wait(&root->fs_info->transaction_wait, &wait,
 149                                         TASK_UNINTERRUPTIBLE);
 150                         if (!cur_trans->blocked)
 151                                 break;
 152                         mutex_unlock(&root->fs_info->trans_mutex);
 153                         schedule();
 154                         mutex_lock(&root->fs_info->trans_mutex);
 155                 }
 156                 finish_wait(&root->fs_info->transaction_wait, &wait);
 157                 put_transaction(cur_trans);
 158         }
 159 }
 160
 161 enum btrfs_trans_type {
 162         TRANS_START,
 163         TRANS_JOIN,
 164         TRANS_USERSPACE,
 165         TRANS_JOIN_NOLOCK,
 166 };
 167
 168 static int may_wait_transaction(struct btrfs_root *root, int type)
 169 {
 170         if (!root->fs_info->log_root_recovering &&
 171             ((type == TRANS_START && !root->fs_info->open_ioctl_trans) ||
 172              type == TRANS_USERSPACE))
 173                 return 1;
 174         return 0;
 175 }
 176
 177 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 178                                                     u64 num_items, int type)
 179 {
 180         struct btrfs_trans_handle *h;
 181         struct btrfs_transaction *cur_trans;
 182         int retries = 0;
 183         int ret;
 184
 185         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
 186                 return ERR_PTR(-EROFS);
 187 again:
 188         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 189         if (!h)
 190                 return ERR_PTR(-ENOMEM);
 191
 192         if (type != TRANS_JOIN_NOLOCK)
 193                 mutex_lock(&root->fs_info->trans_mutex);
 194         if (may_wait_transaction(root, type))
 195                 wait_current_trans(root);
 196
 197         ret = join_transaction(root);
 198         if (ret < 0) {
 199                 kmem_cache_free(btrfs_trans_handle_cachep, h);
 200                 if (type != TRANS_JOIN_NOLOCK)
 201                         mutex_unlock(&root->fs_info->trans_mutex);
 202                 return ERR_PTR(ret);
 203         }
 204
 205         cur_trans = root->fs_info->running_transaction;
 206         atomic_inc(&cur_trans->use_count);
 207         if (type != TRANS_JOIN_NOLOCK)
 208                 mutex_unlock(&root->fs_info->trans_mutex);
 209
 210         h->transid = cur_trans->transid;
 211         h->transaction = cur_trans;
 212         h->blocks_used = 0;
 213         h->block_group = 0;
 214         h->bytes_reserved = 0;
 215         h->delayed_ref_updates = 0;
 216         h->block_rsv = NULL;
 217
 218         smp_mb();
 219         if (cur_trans->blocked && may_wait_transaction(root, type)) {
 220                 btrfs_commit_transaction(h, root);
 221                 goto again;
 222         }
 223
 224         if (num_items > 0) {
 225                 ret = btrfs_trans_reserve_metadata(h, root, num_items);
 226                 if (ret == -EAGAIN && !retries) {
 227                         retries++;
 228                         btrfs_commit_transaction(h, root);
 229                         goto again;
 230                 } else if (ret == -EAGAIN) {
 231                         /*
 232                          * We have already retried and got EAGAIN, so really we
 233                          * don't have space, so set ret to -ENOSPC.
 234                          */
 235                         ret = -ENOSPC;
 236                 }
 237
 238                 if (ret < 0) {
 239                         btrfs_end_transaction(h, root);
 240                         return ERR_PTR(ret);
 241                 }
 242         }
 243
 244         if (type != TRANS_JOIN_NOLOCK)
 245                 mutex_lock(&root->fs_info->trans_mutex);
 246         record_root_in_trans(h, root);
 247         if (type != TRANS_JOIN_NOLOCK)
 248                 mutex_unlock(&root->fs_info->trans_mutex);
 249
 250         if (!current->journal_info && type != TRANS_USERSPACE)
 251                 current->journal_info = h;
 252         return h;
 253 }
 254
 255 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 256                                                    int num_items)
 257 {
 258         return start_transaction(root, num_items, TRANS_START);
 259 }
 260 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
 261                                                    int num_blocks)
 262 {
 263         return start_transaction(root, 0, TRANS_JOIN);
 264 }
 265
 266 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root,
 267                                                           int num_blocks)
 268 {
 269         return start_transaction(root, 0, TRANS_JOIN_NOLOCK);
 270 }
 271
 272 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
 273                                                          int num_blocks)
 274 {
 275         return start_transaction(r, 0, TRANS_USERSPACE);
 276 }
 277
 278 /* wait for a transaction commit to be fully complete */
 279 static noinline int wait_for_commit(struct btrfs_root *root,
 280                                     struct btrfs_transaction *commit)
 281 {
 282         DEFINE_WAIT(wait);
 283         mutex_lock(&root->fs_info->trans_mutex);
 284         while (!commit->commit_done) {
 285                 prepare_to_wait(&commit->commit_wait, &wait,
 286                                 TASK_UNINTERRUPTIBLE);
 287                 if (commit->commit_done)
 288                         break;
 289                 mutex_unlock(&root->fs_info->trans_mutex);
 290                 schedule();
 291                 mutex_lock(&root->fs_info->trans_mutex);
 292         }
 293         mutex_unlock(&root->fs_info->trans_mutex);
 294         finish_wait(&commit->commit_wait, &wait);
 295         return 0;
 296 }
 297
 298 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 299 {
 300         struct btrfs_transaction *cur_trans = NULL, *t;
 301         int ret;
 302
 303         mutex_lock(&root->fs_info->trans_mutex);
 304
 305         ret = 0;
 306         if (transid) {
 307                 if (transid <= root->fs_info->last_trans_committed)
 308                         goto out_unlock;
 309
 310                 /* find specified transaction */
 311                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 312                         if (t->transid == transid) {
 313                                 cur_trans = t;
 314                                 break;
 315                         }
 316                         if (t->transid > transid)
 317                                 break;
 318                 }
 319                 ret = -EINVAL;
 320                 if (!cur_trans)
 321                         goto out_unlock;  /* bad transid */
 322         } else {
 323                 /* find newest transaction that is committing | committed */
 324                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 325                                             list) {
 326                         if (t->in_commit) {
 327                                 if (t->commit_done)
 328                                         goto out_unlock;
 329                                 cur_trans = t;
 330                                 break;
 331                         }
 332                 }
 333                 if (!cur_trans)
 334                         goto out_unlock;  /* nothing committing|committed */
 335         }
 336
 337         atomic_inc(&cur_trans->use_count);
 338         mutex_unlock(&root->fs_info->trans_mutex);
 339
 340         wait_for_commit(root, cur_trans);
 341
 342         mutex_lock(&root->fs_info->trans_mutex);
 343         put_transaction(cur_trans);
 344         ret = 0;
 345 out_unlock:
 346         mutex_unlock(&root->fs_info->trans_mutex);
 347         return ret;
 348 }
 349
 350 void btrfs_throttle(struct btrfs_root *root)
 351 {
 352         mutex_lock(&root->fs_info->trans_mutex);
 353         if (!root->fs_info->open_ioctl_trans)
 354                 wait_current_trans(root);
 355         mutex_unlock(&root->fs_info->trans_mutex);
 356 }
 357
 358 static int should_end_transaction(struct btrfs_trans_handle *trans,
 359                                   struct btrfs_root *root)
 360 {
 361         int ret;
 362         ret = btrfs_block_rsv_check(trans, root,
 363                                     &root->fs_info->global_block_rsv, 0, 5);
 364         return ret ? 1 : 0;
 365 }
 366
 367 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 368                                  struct btrfs_root *root)
 369 {
 370         struct btrfs_transaction *cur_trans = trans->transaction;
 371         int updates;
 372
 373         if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
 374                 return 1;
 375
 376         updates = trans->delayed_ref_updates;
 377         trans->delayed_ref_updates = 0;
 378         if (updates)
 379                 btrfs_run_delayed_refs(trans, root, updates);
 380
 381         return should_end_transaction(trans, root);
 382 }
 383
 384 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 385                           struct btrfs_root *root, int throttle, int lock)
 386 {
 387         struct btrfs_transaction *cur_trans = trans->transaction;
 388         struct btrfs_fs_info *info = root->fs_info;
 389         int count = 0;
 390
 391         while (count < 4) {
 392                 unsigned long cur = trans->delayed_ref_updates;
 393                 trans->delayed_ref_updates = 0;
 394                 if (cur &&
 395                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 396                         trans->delayed_ref_updates = 0;
 397
 398                         /*
 399                          * do a full flush if the transaction is trying
 400                          * to close
 401                          */
 402                         if (trans->transaction->delayed_refs.flushing)
 403                                 cur = 0;
 404                         btrfs_run_delayed_refs(trans, root, cur);
 405                 } else {
 406                         break;
 407                 }
 408                 count++;
 409         }
 410
 411         btrfs_trans_release_metadata(trans, root);
 412
 413         if (lock && !root->fs_info->open_ioctl_trans &&
 414             should_end_transaction(trans, root))
 415                 trans->transaction->blocked = 1;
 416
 417         if (lock && cur_trans->blocked && !cur_trans->in_commit) {
 418                 if (throttle)
 419                         return btrfs_commit_transaction(trans, root);
 420                 else
 421                         wake_up_process(info->transaction_kthread);
 422         }
 423
 424         WARN_ON(cur_trans != info->running_transaction);
 425         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 426         atomic_dec(&cur_trans->num_writers);
 427
 428         smp_mb();
 429         if (waitqueue_active(&cur_trans->writer_wait))
 430                 wake_up(&cur_trans->writer_wait);
 431         put_transaction(cur_trans);
 432
 433         if (current->journal_info == trans)
 434                 current->journal_info = NULL;
 435         memset(trans, 0, sizeof(*trans));
 436         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 437
 438         if (throttle)
 439                 btrfs_run_delayed_iputs(root);
 440
 441         return 0;
 442 }
 443
 444 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 445                           struct btrfs_root *root)
 446 {
 447         int ret;
 448
 449         ret = __btrfs_end_transaction(trans, root, 0, 1);
 450         if (ret)
 451                 return ret;
 452         return 0;
 453 }
 454
 455 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 456                                    struct btrfs_root *root)
 457 {
 458         int ret;
 459
 460         ret = __btrfs_end_transaction(trans, root, 1, 1);
 461         if (ret)
 462                 return ret;
 463         return 0;
 464 }
 465
 466 int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
 467                                  struct btrfs_root *root)
 468 {
 469         int ret;
 470
 471         ret = __btrfs_end_transaction(trans, root, 0, 0);
 472         if (ret)
 473                 return ret;
 474         return 0;
 475 }
 476
 477 int btrfs_end_transaction_dmeta(struct btrfs_trans_handle *trans,
 478                                 struct btrfs_root *root)
 479 {
 480         return __btrfs_end_transaction(trans, root, 1, 1);
 481 }
 482
 483 /*
 484  * when btree blocks are allocated, they have some corresponding bits set for
 485  * them in one of two extent_io trees.  This is used to make sure all of
 486  * those extents are sent to disk but does not wait on them
 487  */
 488 int btrfs_write_marked_extents(struct btrfs_root *root,
 489                                struct extent_io_tree *dirty_pages, int mark)
 490 {
 491         int ret;
 492         int err = 0;
 493         int werr = 0;
 494         struct page *page;
 495         struct inode *btree_inode = root->fs_info->btree_inode;
 496         u64 start = 0;
 497         u64 end;
 498         unsigned long index;
 499
 500         while (1) {
 501                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 502                                             mark);
 503                 if (ret)
 504                         break;
 505                 while (start <= end) {
 506                         cond_resched();
 507
 508                         index = start >> PAGE_CACHE_SHIFT;
 509                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 510                         page = find_get_page(btree_inode->i_mapping, index);
 511                         if (!page)
 512                                 continue;
 513
 514                         btree_lock_page_hook(page);
 515                         if (!page->mapping) {
 516                                 unlock_page(page);
 517                                 page_cache_release(page);
 518                                 continue;
 519                         }
 520
 521                         if (PageWriteback(page)) {
 522                                 if (PageDirty(page))
 523                                         wait_on_page_writeback(page);
 524                                 else {
 525                                         unlock_page(page);
 526                                         page_cache_release(page);
 527                                         continue;
 528                                 }
 529                         }
 530                         err = write_one_page(page, 0);
 531                         if (err)
 532                                 werr = err;
 533                         page_cache_release(page);
 534                 }
 535         }
 536         if (err)
 537                 werr = err;
 538         return werr;
 539 }
 540
 541 /*
 542  * when btree blocks are allocated, they have some corresponding bits set for
 543  * them in one of two extent_io trees.  This is used to make sure all of
 544  * those extents are on disk for transaction or log commit.  We wait
 545  * on all the pages and clear them from the dirty pages state tree
 546  */
 547 int btrfs_wait_marked_extents(struct btrfs_root *root,
 548                               struct extent_io_tree *dirty_pages, int mark)
 549 {
 550         int ret;
 551         int err = 0;
 552         int werr = 0;
 553         struct page *page;
 554         struct inode *btree_inode = root->fs_info->btree_inode;
 555         u64 start = 0;
 556         u64 end;
 557         unsigned long index;
 558
 559         while (1) {
 560                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 561                                             mark);
 562                 if (ret)
 563                         break;
 564
 565                 clear_extent_bits(dirty_pages, start, end, mark, GFP_NOFS);
 566                 while (start <= end) {
 567                         index = start >> PAGE_CACHE_SHIFT;
 568                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 569                         page = find_get_page(btree_inode->i_mapping, index);
 570                         if (!page)
 571                                 continue;
 572                         if (PageDirty(page)) {
 573                                 btree_lock_page_hook(page);
 574                                 wait_on_page_writeback(page);
 575                                 err = write_one_page(page, 0);
 576                                 if (err)
 577                                         werr = err;
 578                         }
 579                         wait_on_page_writeback(page);
 580                         page_cache_release(page);
 581                         cond_resched();
 582                 }
 583         }
 584         if (err)
 585                 werr = err;
 586         return werr;
 587 }
 588
 589 /*
 590  * when btree blocks are allocated, they have some corresponding bits set for
 591  * them in one of two extent_io trees.  This is used to make sure all of
 592  * those extents are on disk for transaction or log commit
 593  */
 594 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 595                                 struct extent_io_tree *dirty_pages, int mark)
 596 {
 597         int ret;
 598         int ret2;
 599
 600         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 601         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 602         return ret || ret2;
 603 }
 604
 605 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 606                                      struct btrfs_root *root)
 607 {
 608         if (!trans || !trans->transaction) {
 609                 struct inode *btree_inode;
 610                 btree_inode = root->fs_info->btree_inode;
 611                 return filemap_write_and_wait(btree_inode->i_mapping);
 612         }
 613         return btrfs_write_and_wait_marked_extents(root,
 614                                            &trans->transaction->dirty_pages,
 615                                            EXTENT_DIRTY);
 616 }
 617
 618 /*
 619  * this is used to update the root pointer in the tree of tree roots.
 620  *
 621  * But, in the case of the extent allocation tree, updating the root
 622  * pointer may allocate blocks which may change the root of the extent
 623  * allocation tree.
 624  *
 625  * So, this loops and repeats and makes sure the cowonly root didn't
 626  * change while the root pointer was being updated in the metadata.
 627  */
 628 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 629                                struct btrfs_root *root)
 630 {
 631         int ret;
 632         u64 old_root_bytenr;
 633         u64 old_root_used;
 634         struct btrfs_root *tree_root = root->fs_info->tree_root;
 635
 636         old_root_used = btrfs_root_used(&root->root_item);
 637         btrfs_write_dirty_block_groups(trans, root);
 638
 639         while (1) {
 640                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 641                 if (old_root_bytenr == root->node->start &&
 642                     old_root_used == btrfs_root_used(&root->root_item))
 643                         break;
 644
 645                 btrfs_set_root_node(&root->root_item, root->node);
 646                 ret = btrfs_update_root(trans, tree_root,
 647                                         &root->root_key,
 648                                         &root->root_item);
 649                 BUG_ON(ret);
 650
 651                 old_root_used = btrfs_root_used(&root->root_item);
 652                 ret = btrfs_write_dirty_block_groups(trans, root);
 653                 BUG_ON(ret);
 654         }
 655
 656         if (root != root->fs_info->extent_root)
 657                 switch_commit_root(root);
 658
 659         return 0;
 660 }
 661
 662 /*
 663  * update all the cowonly tree roots on disk
 664  */
 665 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 666                                          struct btrfs_root *root)
 667 {
 668         struct btrfs_fs_info *fs_info = root->fs_info;
 669         struct list_head *next;
 670         struct extent_buffer *eb;
 671         int ret;
 672
 673         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 674         BUG_ON(ret);
 675
 676         eb = btrfs_lock_root_node(fs_info->tree_root);
 677         btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
 678         btrfs_tree_unlock(eb);
 679         free_extent_buffer(eb);
 680
 681         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 682         BUG_ON(ret);
 683
 684         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 685                 next = fs_info->dirty_cowonly_roots.next;
 686                 list_del_init(next);
 687                 root = list_entry(next, struct btrfs_root, dirty_list);
 688
 689                 update_cowonly_root(trans, root);
 690         }
 691
 692         down_write(&fs_info->extent_commit_sem);
 693         switch_commit_root(fs_info->extent_root);
 694         up_write(&fs_info->extent_commit_sem);
 695
 696         return 0;
 697 }
 698
 699 /*
 700  * dead roots are old snapshots that need to be deleted.  This allocates
 701  * a dirty root struct and adds it into the list of dead roots that need to
 702  * be deleted
 703  */
 704 int btrfs_add_dead_root(struct btrfs_root *root)
 705 {
 706         mutex_lock(&root->fs_info->trans_mutex);
 707         list_add(&root->root_list, &root->fs_info->dead_roots);
 708         mutex_unlock(&root->fs_info->trans_mutex);
 709         return 0;
 710 }
 711
 712 /*
 713  * update all the cowonly tree roots on disk
 714  */
 715 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 716                                     struct btrfs_root *root)
 717 {
 718         struct btrfs_root *gang[8];
 719         struct btrfs_fs_info *fs_info = root->fs_info;
 720         int i;
 721         int ret;
 722         int err = 0;
 723
 724         while (1) {
 725                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
 726                                                  (void **)gang, 0,
 727                                                  ARRAY_SIZE(gang),
 728                                                  BTRFS_ROOT_TRANS_TAG);
 729                 if (ret == 0)
 730                         break;
 731                 for (i = 0; i < ret; i++) {
 732                         root = gang[i];
 733                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
 734                                         (unsigned long)root->root_key.objectid,
 735                                         BTRFS_ROOT_TRANS_TAG);
 736
 737                         btrfs_free_log(trans, root);
 738                         btrfs_update_reloc_root(trans, root);
 739                         btrfs_orphan_commit_root(trans, root);
 740
 741                         btrfs_save_ino_cache(root, trans);
 742
 743                         if (root->commit_root != root->node) {
 744                                 mutex_lock(&root->fs_commit_mutex);
 745                                 switch_commit_root(root);
 746                                 btrfs_unpin_free_ino(root);
 747                                 mutex_unlock(&root->fs_commit_mutex);
 748
 749                                 btrfs_set_root_node(&root->root_item,
 750                                                     root->node);
 751                         }
 752
 753                         err = btrfs_update_root(trans, fs_info->tree_root,
 754                                                 &root->root_key,
 755                                                 &root->root_item);
 756                         if (err)
 757                                 break;
 758                 }
 759         }
 760         return err;
 761 }
 762
 763 /*
 764  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
 765  * otherwise every leaf in the btree is read and defragged.
 766  */
 767 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 768 {
 769         struct btrfs_fs_info *info = root->fs_info;
 770         struct btrfs_trans_handle *trans;
 771         int ret;
 772         unsigned long nr;
 773
 774         if (xchg(&root->defrag_running, 1))
 775                 return 0;
 776
 777         while (1) {
 778                 trans = btrfs_start_transaction(root, 0);
 779                 if (IS_ERR(trans))
 780                         return PTR_ERR(trans);
 781
 782                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 783
 784                 nr = trans->blocks_used;
 785                 btrfs_end_transaction(trans, root);
 786                 btrfs_btree_balance_dirty(info->tree_root, nr);
 787                 cond_resched();
 788
 789                 if (root->fs_info->closing || ret != -EAGAIN)
 790                         break;
 791         }
 792         root->defrag_running = 0;
 793         return ret;
 794 }
 795
 796 /*
 797  * new snapshots need to be created at a very specific time in the
 798  * transaction commit.  This does the actual creation
 799  */
 800 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 801                                    struct btrfs_fs_info *fs_info,
 802                                    struct btrfs_pending_snapshot *pending)
 803 {
 804         struct btrfs_key key;
 805         struct btrfs_root_item *new_root_item;
 806         struct btrfs_root *tree_root = fs_info->tree_root;
 807         struct btrfs_root *root = pending->root;
 808         struct btrfs_root *parent_root;
 809         struct inode *parent_inode;
 810         struct dentry *parent;
 811         struct dentry *dentry;
 812         struct extent_buffer *tmp;
 813         struct extent_buffer *old;
 814         int ret;
 815         u64 to_reserve = 0;
 816         u64 index = 0;
 817         u64 objectid;
 818         u64 root_flags;
 819
 820         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 821         if (!new_root_item) {
 822                 pending->error = -ENOMEM;
 823                 goto fail;
 824         }
 825
 826         ret = btrfs_find_free_objectid(tree_root, &objectid);
 827         if (ret) {
 828                 pending->error = ret;
 829                 goto fail;
 830         }
 831
 832         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
 833         btrfs_orphan_pre_snapshot(trans, pending, &to_reserve);
 834
 835         if (to_reserve > 0) {
 836                 ret = btrfs_block_rsv_add(trans, root, &pending->block_rsv,
 837                                           to_reserve);
 838                 if (ret) {
 839                         pending->error = ret;
 840                         goto fail;
 841                 }
 842         }
 843
 844         key.objectid = objectid;
 845         key.offset = (u64)-1;
 846         key.type = BTRFS_ROOT_ITEM_KEY;
 847
 848         trans->block_rsv = &pending->block_rsv;
 849
 850         dentry = pending->dentry;
 851         parent = dget_parent(dentry);
 852         parent_inode = parent->d_inode;
 853         parent_root = BTRFS_I(parent_inode)->root;
 854         record_root_in_trans(trans, parent_root);
 855
 856         /*
 857          * insert the directory item
 858          */
 859         ret = btrfs_set_inode_index(parent_inode, &index);
 860         BUG_ON(ret);
 861         ret = btrfs_insert_dir_item(trans, parent_root,
 862                                 dentry->d_name.name, dentry->d_name.len,
 863                                 parent_inode, &key,
 864                                 BTRFS_FT_DIR, index);
 865         BUG_ON(ret);
 866
 867         btrfs_i_size_write(parent_inode, parent_inode->i_size +
 868                                          dentry->d_name.len * 2);
 869         ret = btrfs_update_inode(trans, parent_root, parent_inode);
 870         BUG_ON(ret);
 871
 872         record_root_in_trans(trans, root);
 873         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
 874         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
 875         btrfs_check_and_init_root_item(new_root_item);
 876
 877         root_flags = btrfs_root_flags(new_root_item);
 878         if (pending->readonly)
 879                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
 880         else
 881                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
 882         btrfs_set_root_flags(new_root_item, root_flags);
 883
 884         old = btrfs_lock_root_node(root);
 885         btrfs_cow_block(trans, root, old, NULL, 0, &old);
 886         btrfs_set_lock_blocking(old);
 887
 888         btrfs_copy_root(trans, root, old, &tmp, objectid);
 889         btrfs_tree_unlock(old);
 890         free_extent_buffer(old);
 891
 892         btrfs_set_root_node(new_root_item, tmp);
 893         /* record when the snapshot was created in key.offset */
 894         key.offset = trans->transid;
 895         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
 896         btrfs_tree_unlock(tmp);
 897         free_extent_buffer(tmp);
 898         BUG_ON(ret);
 899
 900         /*
 901          * insert root back/forward references
 902          */
 903         ret = btrfs_add_root_ref(trans, tree_root, objectid,
 904                                  parent_root->root_key.objectid,
 905                                  btrfs_ino(parent_inode), index,
 906                                  dentry->d_name.name, dentry->d_name.len);
 907         BUG_ON(ret);
 908         dput(parent);
 909
 910         key.offset = (u64)-1;
 911         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
 912         BUG_ON(IS_ERR(pending->snap));
 913
 914         btrfs_reloc_post_snapshot(trans, pending);
 915         btrfs_orphan_post_snapshot(trans, pending);
 916 fail:
 917         kfree(new_root_item);
 918         btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
 919         return 0;
 920 }
 921
 922 /*
 923  * create all the snapshots we've scheduled for creation
 924  */
 925 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
 926                                              struct btrfs_fs_info *fs_info)
 927 {
 928         struct btrfs_pending_snapshot *pending;
 929         struct list_head *head = &trans->transaction->pending_snapshots;
 930         int ret;
 931
 932         list_for_each_entry(pending, head, list) {
 933                 /*
 934                  * We must deal with the delayed items before creating
 935                  * snapshots, or we will create a snapthot with inconsistent
 936                  * information.
 937                 */
 938                 ret = btrfs_run_delayed_items(trans, fs_info->fs_root);
 939                 BUG_ON(ret);
 940
 941                 ret = create_pending_snapshot(trans, fs_info, pending);
 942                 BUG_ON(ret);
 943         }
 944         return 0;
 945 }
 946
 947 static void update_super_roots(struct btrfs_root *root)
 948 {
 949         struct btrfs_root_item *root_item;
 950         struct btrfs_super_block *super;
 951
 952         super = &root->fs_info->super_copy;
 953
 954         root_item = &root->fs_info->chunk_root->root_item;
 955         super->chunk_root = root_item->bytenr;
 956         super->chunk_root_generation = root_item->generation;
 957         super->chunk_root_level = root_item->level;
 958
 959         root_item = &root->fs_info->tree_root->root_item;
 960         super->root = root_item->bytenr;
 961         super->generation = root_item->generation;
 962         super->root_level = root_item->level;
 963         if (super->cache_generation != 0 || btrfs_test_opt(root, SPACE_CACHE))
 964                 super->cache_generation = root_item->generation;
 965 }
 966
 967 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
 968 {
 969         int ret = 0;
 970         spin_lock(&info->new_trans_lock);
 971         if (info->running_transaction)
 972                 ret = info->running_transaction->in_commit;
 973         spin_unlock(&info->new_trans_lock);
 974         return ret;
 975 }
 976
 977 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
 978 {
 979         int ret = 0;
 980         spin_lock(&info->new_trans_lock);
 981         if (info->running_transaction)
 982                 ret = info->running_transaction->blocked;
 983         spin_unlock(&info->new_trans_lock);
 984         return ret;
 985 }
 986
 987 /*
 988  * wait for the current transaction commit to start and block subsequent
 989  * transaction joins
 990  */
 991 static void wait_current_trans_commit_start(struct btrfs_root *root,
 992                                             struct btrfs_transaction *trans)
 993 {
 994         DEFINE_WAIT(wait);
 995
 996         if (trans->in_commit)
 997                 return;
 998
 999         while (1) {
1000                 prepare_to_wait(&root->fs_info->transaction_blocked_wait, &wait,
1001                                 TASK_UNINTERRUPTIBLE);
1002                 if (trans->in_commit) {
1003                         finish_wait(&root->fs_info->transaction_blocked_wait,
1004                                     &wait);
1005                         break;
1006                 }
1007                 mutex_unlock(&root->fs_info->trans_mutex);
1008                 schedule();
1009                 mutex_lock(&root->fs_info->trans_mutex);
1010                 finish_wait(&root->fs_info->transaction_blocked_wait, &wait);
1011         }
1012 }
1013
1014 /*
1015  * wait for the current transaction to start and then become unblocked.
1016  * caller holds ref.
1017  */
1018 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1019                                          struct btrfs_transaction *trans)
1020 {
1021         DEFINE_WAIT(wait);
1022
1023         if (trans->commit_done || (trans->in_commit && !trans->blocked))
1024                 return;
1025
1026         while (1) {
1027                 prepare_to_wait(&root->fs_info->transaction_wait, &wait,
1028                                 TASK_UNINTERRUPTIBLE);
1029                 if (trans->commit_done ||
1030                     (trans->in_commit && !trans->blocked)) {
1031                         finish_wait(&root->fs_info->transaction_wait,
1032                                     &wait);
1033                         break;
1034                 }
1035                 mutex_unlock(&root->fs_info->trans_mutex);
1036                 schedule();
1037                 mutex_lock(&root->fs_info->trans_mutex);
1038                 finish_wait(&root->fs_info->transaction_wait,
1039                             &wait);
1040         }
1041 }
1042
1043 /*
1044  * commit transactions asynchronously. once btrfs_commit_transaction_async
1045  * returns, any subsequent transaction will not be allowed to join.
1046  */
1047 struct btrfs_async_commit {
1048         struct btrfs_trans_handle *newtrans;
1049         struct btrfs_root *root;
1050         struct delayed_work work;
1051 };
1052
1053 static void do_async_commit(struct work_struct *work)
1054 {
1055         struct btrfs_async_commit *ac =
1056                 container_of(work, struct btrfs_async_commit, work.work);
1057
1058         btrfs_commit_transaction(ac->newtrans, ac->root);
1059         kfree(ac);
1060 }
1061
1062 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1063                                    struct btrfs_root *root,
1064                                    int wait_for_unblock)
1065 {
1066         struct btrfs_async_commit *ac;
1067         struct btrfs_transaction *cur_trans;
1068
1069         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1070         if (!ac)
1071                 return -ENOMEM;
1072
1073         INIT_DELAYED_WORK(&ac->work, do_async_commit);
1074         ac->root = root;
1075         ac->newtrans = btrfs_join_transaction(root, 0);
1076         if (IS_ERR(ac->newtrans)) {
1077                 int err = PTR_ERR(ac->newtrans);
1078                 kfree(ac);
1079                 return err;
1080         }
1081
1082         /* take transaction reference */
1083         mutex_lock(&root->fs_info->trans_mutex);
1084         cur_trans = trans->transaction;
1085         atomic_inc(&cur_trans->use_count);
1086         mutex_unlock(&root->fs_info->trans_mutex);
1087
1088         btrfs_end_transaction(trans, root);
1089         schedule_delayed_work(&ac->work, 0);
1090
1091         /* wait for transaction to start and unblock */
1092         mutex_lock(&root->fs_info->trans_mutex);
1093         if (wait_for_unblock)
1094                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1095         else
1096                 wait_current_trans_commit_start(root, cur_trans);
1097         put_transaction(cur_trans);
1098         mutex_unlock(&root->fs_info->trans_mutex);
1099
1100         return 0;
1101 }
1102
1103 /*
1104  * btrfs_transaction state sequence:
1105  *    in_commit = 0, blocked = 0  (initial)
1106  *    in_commit = 1, blocked = 1
1107  *    blocked = 0
1108  *    commit_done = 1
1109  */
1110 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1111                              struct btrfs_root *root)
1112 {
1113         unsigned long joined = 0;
1114         struct btrfs_transaction *cur_trans;
1115         struct btrfs_transaction *prev_trans = NULL;
1116         DEFINE_WAIT(wait);
1117         int ret;
1118         int should_grow = 0;
1119         unsigned long now = get_seconds();
1120         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1121
1122         btrfs_run_ordered_operations(root, 0);
1123
1124         /* make a pass through all the delayed refs we have so far
1125          * any runnings procs may add more while we are here
1126          */
1127         ret = btrfs_run_delayed_refs(trans, root, 0);
1128         BUG_ON(ret);
1129
1130         btrfs_trans_release_metadata(trans, root);
1131
1132         cur_trans = trans->transaction;
1133         /*
1134          * set the flushing flag so procs in this transaction have to
1135          * start sending their work down.
1136          */
1137         cur_trans->delayed_refs.flushing = 1;
1138
1139         ret = btrfs_run_delayed_refs(trans, root, 0);
1140         BUG_ON(ret);
1141
1142         mutex_lock(&root->fs_info->trans_mutex);
1143         if (cur_trans->in_commit) {
1144                 atomic_inc(&cur_trans->use_count);
1145                 mutex_unlock(&root->fs_info->trans_mutex);
1146                 btrfs_end_transaction(trans, root);
1147
1148                 ret = wait_for_commit(root, cur_trans);
1149                 BUG_ON(ret);
1150
1151                 mutex_lock(&root->fs_info->trans_mutex);
1152                 put_transaction(cur_trans);
1153                 mutex_unlock(&root->fs_info->trans_mutex);
1154
1155                 return 0;
1156         }
1157
1158         trans->transaction->in_commit = 1;
1159         trans->transaction->blocked = 1;
1160         wake_up(&root->fs_info->transaction_blocked_wait);
1161
1162         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1163                 prev_trans = list_entry(cur_trans->list.prev,
1164                                         struct btrfs_transaction, list);
1165                 if (!prev_trans->commit_done) {
1166                         atomic_inc(&prev_trans->use_count);
1167                         mutex_unlock(&root->fs_info->trans_mutex);
1168
1169                         wait_for_commit(root, prev_trans);
1170
1171                         mutex_lock(&root->fs_info->trans_mutex);
1172                         put_transaction(prev_trans);
1173                 }
1174         }
1175
1176         if (now < cur_trans->start_time || now - cur_trans->start_time < 1)
1177                 should_grow = 1;
1178
1179         do {
1180                 int snap_pending = 0;
1181                 joined = cur_trans->num_joined;
1182                 if (!list_empty(&trans->transaction->pending_snapshots))
1183                         snap_pending = 1;
1184
1185                 WARN_ON(cur_trans != trans->transaction);
1186                 mutex_unlock(&root->fs_info->trans_mutex);
1187
1188                 if (flush_on_commit || snap_pending) {
1189                         btrfs_start_delalloc_inodes(root, 1);
1190                         ret = btrfs_wait_ordered_extents(root, 0, 1);
1191                         BUG_ON(ret);
1192                 }
1193
1194                 ret = btrfs_run_delayed_items(trans, root);
1195                 BUG_ON(ret);
1196
1197                 /*
1198                  * rename don't use btrfs_join_transaction, so, once we
1199                  * set the transaction to blocked above, we aren't going
1200                  * to get any new ordered operations.  We can safely run
1201                  * it here and no for sure that nothing new will be added
1202                  * to the list
1203                  */
1204                 btrfs_run_ordered_operations(root, 1);
1205
1206                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1207                                 TASK_UNINTERRUPTIBLE);
1208
1209                 smp_mb();
1210                 if (atomic_read(&cur_trans->num_writers) > 1)
1211                         schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1212                 else if (should_grow)
1213                         schedule_timeout(1);
1214
1215                 mutex_lock(&root->fs_info->trans_mutex);
1216                 finish_wait(&cur_trans->writer_wait, &wait);
1217         } while (atomic_read(&cur_trans->num_writers) > 1 ||
1218                  (should_grow && cur_trans->num_joined != joined));
1219
1220         ret = create_pending_snapshots(trans, root->fs_info);
1221         BUG_ON(ret);
1222
1223         ret = btrfs_run_delayed_items(trans, root);
1224         BUG_ON(ret);
1225
1226         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1227         BUG_ON(ret);
1228
1229         WARN_ON(cur_trans != trans->transaction);
1230
1231         btrfs_scrub_pause(root);
1232         /* btrfs_commit_tree_roots is responsible for getting the
1233          * various roots consistent with each other.  Every pointer
1234          * in the tree of tree roots has to point to the most up to date
1235          * root for every subvolume and other tree.  So, we have to keep
1236          * the tree logging code from jumping in and changing any
1237          * of the trees.
1238          *
1239          * At this point in the commit, there can't be any tree-log
1240          * writers, but a little lower down we drop the trans mutex
1241          * and let new people in.  By holding the tree_log_mutex
1242          * from now until after the super is written, we avoid races
1243          * with the tree-log code.
1244          */
1245         mutex_lock(&root->fs_info->tree_log_mutex);
1246
1247         ret = commit_fs_roots(trans, root);
1248         BUG_ON(ret);
1249
1250         /* commit_fs_roots gets rid of all the tree log roots, it is now
1251          * safe to free the root of tree log roots
1252          */
1253         btrfs_free_log_root_tree(trans, root->fs_info);
1254
1255         ret = commit_cowonly_roots(trans, root);
1256         BUG_ON(ret);
1257
1258         btrfs_prepare_extent_commit(trans, root);
1259
1260         cur_trans = root->fs_info->running_transaction;
1261         spin_lock(&root->fs_info->new_trans_lock);
1262         root->fs_info->running_transaction = NULL;
1263         spin_unlock(&root->fs_info->new_trans_lock);
1264
1265         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1266                             root->fs_info->tree_root->node);
1267         switch_commit_root(root->fs_info->tree_root);
1268
1269         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1270                             root->fs_info->chunk_root->node);
1271         switch_commit_root(root->fs_info->chunk_root);
1272
1273         update_super_roots(root);
1274
1275         if (!root->fs_info->log_root_recovering) {
1276                 btrfs_set_super_log_root(&root->fs_info->super_copy, 0);
1277                 btrfs_set_super_log_root_level(&root->fs_info->super_copy, 0);
1278         }
1279
1280         memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
1281                sizeof(root->fs_info->super_copy));
1282
1283         trans->transaction->blocked = 0;
1284
1285         wake_up(&root->fs_info->transaction_wait);
1286
1287         mutex_unlock(&root->fs_info->trans_mutex);
1288         ret = btrfs_write_and_wait_transaction(trans, root);
1289         BUG_ON(ret);
1290         write_ctree_super(trans, root, 0);
1291
1292         /*
1293          * the super is written, we can safely allow the tree-loggers
1294          * to go about their business
1295          */
1296         mutex_unlock(&root->fs_info->tree_log_mutex);
1297
1298         btrfs_finish_extent_commit(trans, root);
1299
1300         mutex_lock(&root->fs_info->trans_mutex);
1301
1302         cur_trans->commit_done = 1;
1303
1304         root->fs_info->last_trans_committed = cur_trans->transid;
1305
1306         wake_up(&cur_trans->commit_wait);
1307
1308         list_del_init(&cur_trans->list);
1309         put_transaction(cur_trans);
1310         put_transaction(cur_trans);
1311
1312         trace_btrfs_transaction_commit(root);
1313
1314         mutex_unlock(&root->fs_info->trans_mutex);
1315
1316         btrfs_scrub_continue(root);
1317
1318         if (current->journal_info == trans)
1319                 current->journal_info = NULL;
1320
1321         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1322
1323         if (current != root->fs_info->transaction_kthread)
1324                 btrfs_run_delayed_iputs(root);
1325
1326         return ret;
1327 }
1328
1329 /*
1330  * interface function to delete all the snapshots we have scheduled for deletion
1331  */
1332 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1333 {
1334         LIST_HEAD(list);
1335         struct btrfs_fs_info *fs_info = root->fs_info;
1336
1337         mutex_lock(&fs_info->trans_mutex);
1338         list_splice_init(&fs_info->dead_roots, &list);
1339         mutex_unlock(&fs_info->trans_mutex);
1340
1341         while (!list_empty(&list)) {
1342                 root = list_entry(list.next, struct btrfs_root, root_list);
1343                 list_del(&root->root_list);
1344
1345                 btrfs_kill_all_delayed_nodes(root);
1346
1347                 if (btrfs_header_backref_rev(root->node) <
1348                     BTRFS_MIXED_BACKREF_REV)
1349                         btrfs_drop_snapshot(root, NULL, 0);
1350                 else
1351                         btrfs_drop_snapshot(root, NULL, 1);
1352         }
1353         return 0;
1354 }