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
  31 #define BTRFS_ROOT_TRANS_TAG 0
  32
  33 static noinline void put_transaction(struct btrfs_transaction *transaction)
  34 {
  35         WARN_ON(transaction->use_count == 0);
  36         transaction->use_count--;
  37         if (transaction->use_count == 0) {
  38                 list_del_init(&transaction->list);
  39                 memset(transaction, 0, sizeof(*transaction));
  40                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  41         }
  42 }
  43
  44 static noinline void switch_commit_root(struct btrfs_root *root)
  45 {
  46         free_extent_buffer(root->commit_root);
  47         root->commit_root = btrfs_root_node(root);
  48 }
  49
  50 /*
  51  * either allocate a new transaction or hop into the existing one
  52  */
  53 static noinline int join_transaction(struct btrfs_root *root)
  54 {
  55         struct btrfs_transaction *cur_trans;
  56         cur_trans = root->fs_info->running_transaction;
  57         if (!cur_trans) {
  58                 cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
  59                                              GFP_NOFS);
  60                 BUG_ON(!cur_trans);
  61                 root->fs_info->generation++;
  62                 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                 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                                      GFP_NOFS);
  86                 spin_lock(&root->fs_info->new_trans_lock);
  87                 root->fs_info->running_transaction = cur_trans;
  88                 spin_unlock(&root->fs_info->new_trans_lock);
  89         } else {
  90                 cur_trans->num_writers++;
  91                 cur_trans->num_joined++;
  92         }
  93
  94         return 0;
  95 }
  96
  97 /*
  98  * this does all the record keeping required to make sure that a reference
  99  * counted root is properly recorded in a given transaction.  This is required
 100  * to make sure the old root from before we joined the transaction is deleted
 101  * when the transaction commits
 102  */
 103 static noinline int record_root_in_trans(struct btrfs_trans_handle *trans,
 104                                          struct btrfs_root *root)
 105 {
 106         if (root->ref_cows && root->last_trans < trans->transid) {
 107                 WARN_ON(root == root->fs_info->extent_root);
 108                 WARN_ON(root->commit_root != root->node);
 109
 110                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 111                            (unsigned long)root->root_key.objectid,
 112                            BTRFS_ROOT_TRANS_TAG);
 113                 root->last_trans = trans->transid;
 114                 btrfs_init_reloc_root(trans, root);
 115         }
 116         return 0;
 117 }
 118
 119 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 120                                struct btrfs_root *root)
 121 {
 122         if (!root->ref_cows)
 123                 return 0;
 124
 125         mutex_lock(&root->fs_info->trans_mutex);
 126         if (root->last_trans == trans->transid) {
 127                 mutex_unlock(&root->fs_info->trans_mutex);
 128                 return 0;
 129         }
 130
 131         record_root_in_trans(trans, root);
 132         mutex_unlock(&root->fs_info->trans_mutex);
 133         return 0;
 134 }
 135
 136 /* wait for commit against the current transaction to become unblocked
 137  * when this is done, it is safe to start a new transaction, but the current
 138  * transaction might not be fully on disk.
 139  */
 140 static void wait_current_trans(struct btrfs_root *root)
 141 {
 142         struct btrfs_transaction *cur_trans;
 143
 144         cur_trans = root->fs_info->running_transaction;
 145         if (cur_trans && cur_trans->blocked) {
 146                 DEFINE_WAIT(wait);
 147                 cur_trans->use_count++;
 148                 while (1) {
 149                         prepare_to_wait(&root->fs_info->transaction_wait, &wait,
 150                                         TASK_UNINTERRUPTIBLE);
 151                         if (!cur_trans->blocked)
 152                                 break;
 153                         mutex_unlock(&root->fs_info->trans_mutex);
 154                         schedule();
 155                         mutex_lock(&root->fs_info->trans_mutex);
 156                 }
 157                 finish_wait(&root->fs_info->transaction_wait, &wait);
 158                 put_transaction(cur_trans);
 159         }
 160 }
 161
 162 enum btrfs_trans_type {
 163         TRANS_START,
 164         TRANS_JOIN,
 165         TRANS_USERSPACE,
 166         TRANS_JOIN_NOLOCK,
 167 };
 168
 169 static int may_wait_transaction(struct btrfs_root *root, int type)
 170 {
 171         if (!root->fs_info->log_root_recovering &&
 172             ((type == TRANS_START && !root->fs_info->open_ioctl_trans) ||
 173              type == TRANS_USERSPACE))
 174                 return 1;
 175         return 0;
 176 }
 177
 178 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 179                                                     u64 num_items, int type)
 180 {
 181         struct btrfs_trans_handle *h;
 182         struct btrfs_transaction *cur_trans;
 183         int ret;
 184 again:
 185         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 186         if (!h)
 187                 return ERR_PTR(-ENOMEM);
 188
 189         if (type != TRANS_JOIN_NOLOCK)
 190                 mutex_lock(&root->fs_info->trans_mutex);
 191         if (may_wait_transaction(root, type))
 192                 wait_current_trans(root);
 193
 194         ret = join_transaction(root);
 195         BUG_ON(ret);
 196
 197         cur_trans = root->fs_info->running_transaction;
 198         cur_trans->use_count++;
 199         if (type != TRANS_JOIN_NOLOCK)
 200                 mutex_unlock(&root->fs_info->trans_mutex);
 201
 202         h->transid = cur_trans->transid;
 203         h->transaction = cur_trans;
 204         h->blocks_used = 0;
 205         h->block_group = 0;
 206         h->bytes_reserved = 0;
 207         h->delayed_ref_updates = 0;
 208         h->block_rsv = NULL;
 209
 210         smp_mb();
 211         if (cur_trans->blocked && may_wait_transaction(root, type)) {
 212                 btrfs_commit_transaction(h, root);
 213                 goto again;
 214         }
 215
 216         if (num_items > 0) {
 217                 ret = btrfs_trans_reserve_metadata(h, root, num_items);
 218                 if (ret == -EAGAIN) {
 219                         btrfs_commit_transaction(h, root);
 220                         goto again;
 221                 }
 222                 if (ret < 0) {
 223                         btrfs_end_transaction(h, root);
 224                         return ERR_PTR(ret);
 225                 }
 226         }
 227
 228         if (type != TRANS_JOIN_NOLOCK)
 229                 mutex_lock(&root->fs_info->trans_mutex);
 230         record_root_in_trans(h, root);
 231         if (type != TRANS_JOIN_NOLOCK)
 232                 mutex_unlock(&root->fs_info->trans_mutex);
 233
 234         if (!current->journal_info && type != TRANS_USERSPACE)
 235                 current->journal_info = h;
 236         return h;
 237 }
 238
 239 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 240                                                    int num_items)
 241 {
 242         return start_transaction(root, num_items, TRANS_START);
 243 }
 244 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
 245                                                    int num_blocks)
 246 {
 247         return start_transaction(root, 0, TRANS_JOIN);
 248 }
 249
 250 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root,
 251                                                           int num_blocks)
 252 {
 253         return start_transaction(root, 0, TRANS_JOIN_NOLOCK);
 254 }
 255
 256 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
 257                                                          int num_blocks)
 258 {
 259         return start_transaction(r, 0, TRANS_USERSPACE);
 260 }
 261
 262 /* wait for a transaction commit to be fully complete */
 263 static noinline int wait_for_commit(struct btrfs_root *root,
 264                                     struct btrfs_transaction *commit)
 265 {
 266         DEFINE_WAIT(wait);
 267         mutex_lock(&root->fs_info->trans_mutex);
 268         while (!commit->commit_done) {
 269                 prepare_to_wait(&commit->commit_wait, &wait,
 270                                 TASK_UNINTERRUPTIBLE);
 271                 if (commit->commit_done)
 272                         break;
 273                 mutex_unlock(&root->fs_info->trans_mutex);
 274                 schedule();
 275                 mutex_lock(&root->fs_info->trans_mutex);
 276         }
 277         mutex_unlock(&root->fs_info->trans_mutex);
 278         finish_wait(&commit->commit_wait, &wait);
 279         return 0;
 280 }
 281
 282 #if 0
 283 /*
 284  * rate limit against the drop_snapshot code.  This helps to slow down new
 285  * operations if the drop_snapshot code isn't able to keep up.
 286  */
 287 static void throttle_on_drops(struct btrfs_root *root)
 288 {
 289         struct btrfs_fs_info *info = root->fs_info;
 290         int harder_count = 0;
 291
 292 harder:
 293         if (atomic_read(&info->throttles)) {
 294                 DEFINE_WAIT(wait);
 295                 int thr;
 296                 thr = atomic_read(&info->throttle_gen);
 297
 298                 do {
 299                         prepare_to_wait(&info->transaction_throttle,
 300                                         &wait, TASK_UNINTERRUPTIBLE);
 301                         if (!atomic_read(&info->throttles)) {
 302                                 finish_wait(&info->transaction_throttle, &wait);
 303                                 break;
 304                         }
 305                         schedule();
 306                         finish_wait(&info->transaction_throttle, &wait);
 307                 } while (thr == atomic_read(&info->throttle_gen));
 308                 harder_count++;
 309
 310                 if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
 311                     harder_count < 2)
 312                         goto harder;
 313
 314                 if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
 315                     harder_count < 10)
 316                         goto harder;
 317
 318                 if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
 319                     harder_count < 20)
 320                         goto harder;
 321         }
 322 }
 323 #endif
 324
 325 void btrfs_throttle(struct btrfs_root *root)
 326 {
 327         mutex_lock(&root->fs_info->trans_mutex);
 328         if (!root->fs_info->open_ioctl_trans)
 329                 wait_current_trans(root);
 330         mutex_unlock(&root->fs_info->trans_mutex);
 331 }
 332
 333 static int should_end_transaction(struct btrfs_trans_handle *trans,
 334                                   struct btrfs_root *root)
 335 {
 336         int ret;
 337         ret = btrfs_block_rsv_check(trans, root,
 338                                     &root->fs_info->global_block_rsv, 0, 5);
 339         return ret ? 1 : 0;
 340 }
 341
 342 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 343                                  struct btrfs_root *root)
 344 {
 345         struct btrfs_transaction *cur_trans = trans->transaction;
 346         int updates;
 347
 348         if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
 349                 return 1;
 350
 351         updates = trans->delayed_ref_updates;
 352         trans->delayed_ref_updates = 0;
 353         if (updates)
 354                 btrfs_run_delayed_refs(trans, root, updates);
 355
 356         return should_end_transaction(trans, root);
 357 }
 358
 359 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 360                           struct btrfs_root *root, int throttle, int lock)
 361 {
 362         struct btrfs_transaction *cur_trans = trans->transaction;
 363         struct btrfs_fs_info *info = root->fs_info;
 364         int count = 0;
 365
 366         while (count < 4) {
 367                 unsigned long cur = trans->delayed_ref_updates;
 368                 trans->delayed_ref_updates = 0;
 369                 if (cur &&
 370                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 371                         trans->delayed_ref_updates = 0;
 372
 373                         /*
 374                          * do a full flush if the transaction is trying
 375                          * to close
 376                          */
 377                         if (trans->transaction->delayed_refs.flushing)
 378                                 cur = 0;
 379                         btrfs_run_delayed_refs(trans, root, cur);
 380                 } else {
 381                         break;
 382                 }
 383                 count++;
 384         }
 385
 386         btrfs_trans_release_metadata(trans, root);
 387
 388         if (lock && !root->fs_info->open_ioctl_trans &&
 389             should_end_transaction(trans, root))
 390                 trans->transaction->blocked = 1;
 391
 392         if (lock && cur_trans->blocked && !cur_trans->in_commit) {
 393                 if (throttle)
 394                         return btrfs_commit_transaction(trans, root);
 395                 else
 396                         wake_up_process(info->transaction_kthread);
 397         }
 398
 399         if (lock)
 400                 mutex_lock(&info->trans_mutex);
 401         WARN_ON(cur_trans != info->running_transaction);
 402         WARN_ON(cur_trans->num_writers < 1);
 403         cur_trans->num_writers--;
 404
 405         smp_mb();
 406         if (waitqueue_active(&cur_trans->writer_wait))
 407                 wake_up(&cur_trans->writer_wait);
 408         put_transaction(cur_trans);
 409         if (lock)
 410                 mutex_unlock(&info->trans_mutex);
 411
 412         if (current->journal_info == trans)
 413                 current->journal_info = NULL;
 414         memset(trans, 0, sizeof(*trans));
 415         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 416
 417         if (throttle)
 418                 btrfs_run_delayed_iputs(root);
 419
 420         return 0;
 421 }
 422
 423 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 424                           struct btrfs_root *root)
 425 {
 426         return __btrfs_end_transaction(trans, root, 0, 1);
 427 }
 428
 429 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 430                                    struct btrfs_root *root)
 431 {
 432         return __btrfs_end_transaction(trans, root, 1, 1);
 433 }
 434
 435 int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
 436                                  struct btrfs_root *root)
 437 {
 438         return __btrfs_end_transaction(trans, root, 0, 0);
 439 }
 440
 441 /*
 442  * when btree blocks are allocated, they have some corresponding bits set for
 443  * them in one of two extent_io trees.  This is used to make sure all of
 444  * those extents are sent to disk but does not wait on them
 445  */
 446 int btrfs_write_marked_extents(struct btrfs_root *root,
 447                                struct extent_io_tree *dirty_pages, int mark)
 448 {
 449         int ret;
 450         int err = 0;
 451         int werr = 0;
 452         struct page *page;
 453         struct inode *btree_inode = root->fs_info->btree_inode;
 454         u64 start = 0;
 455         u64 end;
 456         unsigned long index;
 457
 458         while (1) {
 459                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 460                                             mark);
 461                 if (ret)
 462                         break;
 463                 while (start <= end) {
 464                         cond_resched();
 465
 466                         index = start >> PAGE_CACHE_SHIFT;
 467                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 468                         page = find_get_page(btree_inode->i_mapping, index);
 469                         if (!page)
 470                                 continue;
 471
 472                         btree_lock_page_hook(page);
 473                         if (!page->mapping) {
 474                                 unlock_page(page);
 475                                 page_cache_release(page);
 476                                 continue;
 477                         }
 478
 479                         if (PageWriteback(page)) {
 480                                 if (PageDirty(page))
 481                                         wait_on_page_writeback(page);
 482                                 else {
 483                                         unlock_page(page);
 484                                         page_cache_release(page);
 485                                         continue;
 486                                 }
 487                         }
 488                         err = write_one_page(page, 0);
 489                         if (err)
 490                                 werr = err;
 491                         page_cache_release(page);
 492                 }
 493         }
 494         if (err)
 495                 werr = err;
 496         return werr;
 497 }
 498
 499 /*
 500  * when btree blocks are allocated, they have some corresponding bits set for
 501  * them in one of two extent_io trees.  This is used to make sure all of
 502  * those extents are on disk for transaction or log commit.  We wait
 503  * on all the pages and clear them from the dirty pages state tree
 504  */
 505 int btrfs_wait_marked_extents(struct btrfs_root *root,
 506                               struct extent_io_tree *dirty_pages, int mark)
 507 {
 508         int ret;
 509         int err = 0;
 510         int werr = 0;
 511         struct page *page;
 512         struct inode *btree_inode = root->fs_info->btree_inode;
 513         u64 start = 0;
 514         u64 end;
 515         unsigned long index;
 516
 517         while (1) {
 518                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 519                                             mark);
 520                 if (ret)
 521                         break;
 522
 523                 clear_extent_bits(dirty_pages, start, end, mark, GFP_NOFS);
 524                 while (start <= end) {
 525                         index = start >> PAGE_CACHE_SHIFT;
 526                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 527                         page = find_get_page(btree_inode->i_mapping, index);
 528                         if (!page)
 529                                 continue;
 530                         if (PageDirty(page)) {
 531                                 btree_lock_page_hook(page);
 532                                 wait_on_page_writeback(page);
 533                                 err = write_one_page(page, 0);
 534                                 if (err)
 535                                         werr = err;
 536                         }
 537                         wait_on_page_writeback(page);
 538                         page_cache_release(page);
 539                         cond_resched();
 540                 }
 541         }
 542         if (err)
 543                 werr = err;
 544         return werr;
 545 }
 546
 547 /*
 548  * when btree blocks are allocated, they have some corresponding bits set for
 549  * them in one of two extent_io trees.  This is used to make sure all of
 550  * those extents are on disk for transaction or log commit
 551  */
 552 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 553                                 struct extent_io_tree *dirty_pages, int mark)
 554 {
 555         int ret;
 556         int ret2;
 557
 558         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 559         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 560         return ret || ret2;
 561 }
 562
 563 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 564                                      struct btrfs_root *root)
 565 {
 566         if (!trans || !trans->transaction) {
 567                 struct inode *btree_inode;
 568                 btree_inode = root->fs_info->btree_inode;
 569                 return filemap_write_and_wait(btree_inode->i_mapping);
 570         }
 571         return btrfs_write_and_wait_marked_extents(root,
 572                                            &trans->transaction->dirty_pages,
 573                                            EXTENT_DIRTY);
 574 }
 575
 576 /*
 577  * this is used to update the root pointer in the tree of tree roots.
 578  *
 579  * But, in the case of the extent allocation tree, updating the root
 580  * pointer may allocate blocks which may change the root of the extent
 581  * allocation tree.
 582  *
 583  * So, this loops and repeats and makes sure the cowonly root didn't
 584  * change while the root pointer was being updated in the metadata.
 585  */
 586 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 587                                struct btrfs_root *root)
 588 {
 589         int ret;
 590         u64 old_root_bytenr;
 591         u64 old_root_used;
 592         struct btrfs_root *tree_root = root->fs_info->tree_root;
 593
 594         old_root_used = btrfs_root_used(&root->root_item);
 595         btrfs_write_dirty_block_groups(trans, root);
 596
 597         while (1) {
 598                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 599                 if (old_root_bytenr == root->node->start &&
 600                     old_root_used == btrfs_root_used(&root->root_item))
 601                         break;
 602
 603                 btrfs_set_root_node(&root->root_item, root->node);
 604                 ret = btrfs_update_root(trans, tree_root,
 605                                         &root->root_key,
 606                                         &root->root_item);
 607                 BUG_ON(ret);
 608
 609                 old_root_used = btrfs_root_used(&root->root_item);
 610                 ret = btrfs_write_dirty_block_groups(trans, root);
 611                 BUG_ON(ret);
 612         }
 613
 614         if (root != root->fs_info->extent_root)
 615                 switch_commit_root(root);
 616
 617         return 0;
 618 }
 619
 620 /*
 621  * update all the cowonly tree roots on disk
 622  */
 623 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 624                                          struct btrfs_root *root)
 625 {
 626         struct btrfs_fs_info *fs_info = root->fs_info;
 627         struct list_head *next;
 628         struct extent_buffer *eb;
 629         int ret;
 630
 631         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 632         BUG_ON(ret);
 633
 634         eb = btrfs_lock_root_node(fs_info->tree_root);
 635         btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
 636         btrfs_tree_unlock(eb);
 637         free_extent_buffer(eb);
 638
 639         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 640         BUG_ON(ret);
 641
 642         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 643                 next = fs_info->dirty_cowonly_roots.next;
 644                 list_del_init(next);
 645                 root = list_entry(next, struct btrfs_root, dirty_list);
 646
 647                 update_cowonly_root(trans, root);
 648         }
 649
 650         down_write(&fs_info->extent_commit_sem);
 651         switch_commit_root(fs_info->extent_root);
 652         up_write(&fs_info->extent_commit_sem);
 653
 654         return 0;
 655 }
 656
 657 /*
 658  * dead roots are old snapshots that need to be deleted.  This allocates
 659  * a dirty root struct and adds it into the list of dead roots that need to
 660  * be deleted
 661  */
 662 int btrfs_add_dead_root(struct btrfs_root *root)
 663 {
 664         mutex_lock(&root->fs_info->trans_mutex);
 665         list_add(&root->root_list, &root->fs_info->dead_roots);
 666         mutex_unlock(&root->fs_info->trans_mutex);
 667         return 0;
 668 }
 669
 670 /*
 671  * update all the cowonly tree roots on disk
 672  */
 673 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 674                                     struct btrfs_root *root)
 675 {
 676         struct btrfs_root *gang[8];
 677         struct btrfs_fs_info *fs_info = root->fs_info;
 678         int i;
 679         int ret;
 680         int err = 0;
 681
 682         while (1) {
 683                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
 684                                                  (void **)gang, 0,
 685                                                  ARRAY_SIZE(gang),
 686                                                  BTRFS_ROOT_TRANS_TAG);
 687                 if (ret == 0)
 688                         break;
 689                 for (i = 0; i < ret; i++) {
 690                         root = gang[i];
 691                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
 692                                         (unsigned long)root->root_key.objectid,
 693                                         BTRFS_ROOT_TRANS_TAG);
 694
 695                         btrfs_free_log(trans, root);
 696                         btrfs_update_reloc_root(trans, root);
 697                         btrfs_orphan_commit_root(trans, root);
 698
 699                         if (root->commit_root != root->node) {
 700                                 switch_commit_root(root);
 701                                 btrfs_set_root_node(&root->root_item,
 702                                                     root->node);
 703                         }
 704
 705                         err = btrfs_update_root(trans, fs_info->tree_root,
 706                                                 &root->root_key,
 707                                                 &root->root_item);
 708                         if (err)
 709                                 break;
 710                 }
 711         }
 712         return err;
 713 }
 714
 715 /*
 716  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
 717  * otherwise every leaf in the btree is read and defragged.
 718  */
 719 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 720 {
 721         struct btrfs_fs_info *info = root->fs_info;
 722         struct btrfs_trans_handle *trans;
 723         int ret;
 724         unsigned long nr;
 725
 726         if (xchg(&root->defrag_running, 1))
 727                 return 0;
 728
 729         while (1) {
 730                 trans = btrfs_start_transaction(root, 0);
 731                 if (IS_ERR(trans))
 732                         return PTR_ERR(trans);
 733
 734                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 735
 736                 nr = trans->blocks_used;
 737                 btrfs_end_transaction(trans, root);
 738                 btrfs_btree_balance_dirty(info->tree_root, nr);
 739                 cond_resched();
 740
 741                 if (root->fs_info->closing || ret != -EAGAIN)
 742                         break;
 743         }
 744         root->defrag_running = 0;
 745         return ret;
 746 }
 747
 748 #if 0
 749 /*
 750  * when dropping snapshots, we generate a ton of delayed refs, and it makes
 751  * sense not to join the transaction while it is trying to flush the current
 752  * queue of delayed refs out.
 753  *
 754  * This is used by the drop snapshot code only
 755  */
 756 static noinline int wait_transaction_pre_flush(struct btrfs_fs_info *info)
 757 {
 758         DEFINE_WAIT(wait);
 759
 760         mutex_lock(&info->trans_mutex);
 761         while (info->running_transaction &&
 762                info->running_transaction->delayed_refs.flushing) {
 763                 prepare_to_wait(&info->transaction_wait, &wait,
 764                                 TASK_UNINTERRUPTIBLE);
 765                 mutex_unlock(&info->trans_mutex);
 766
 767                 schedule();
 768
 769                 mutex_lock(&info->trans_mutex);
 770                 finish_wait(&info->transaction_wait, &wait);
 771         }
 772         mutex_unlock(&info->trans_mutex);
 773         return 0;
 774 }
 775
 776 /*
 777  * Given a list of roots that need to be deleted, call btrfs_drop_snapshot on
 778  * all of them
 779  */
 780 int btrfs_drop_dead_root(struct btrfs_root *root)
 781 {
 782         struct btrfs_trans_handle *trans;
 783         struct btrfs_root *tree_root = root->fs_info->tree_root;
 784         unsigned long nr;
 785         int ret;
 786
 787         while (1) {
 788                 /*
 789                  * we don't want to jump in and create a bunch of
 790                  * delayed refs if the transaction is starting to close
 791                  */
 792                 wait_transaction_pre_flush(tree_root->fs_info);
 793                 trans = btrfs_start_transaction(tree_root, 1);
 794
 795                 /*
 796                  * we've joined a transaction, make sure it isn't
 797                  * closing right now
 798                  */
 799                 if (trans->transaction->delayed_refs.flushing) {
 800                         btrfs_end_transaction(trans, tree_root);
 801                         continue;
 802                 }
 803
 804                 ret = btrfs_drop_snapshot(trans, root);
 805                 if (ret != -EAGAIN)
 806                         break;
 807
 808                 ret = btrfs_update_root(trans, tree_root,
 809                                         &root->root_key,
 810                                         &root->root_item);
 811                 if (ret)
 812                         break;
 813
 814                 nr = trans->blocks_used;
 815                 ret = btrfs_end_transaction(trans, tree_root);
 816                 BUG_ON(ret);
 817
 818                 btrfs_btree_balance_dirty(tree_root, nr);
 819                 cond_resched();
 820         }
 821         BUG_ON(ret);
 822
 823         ret = btrfs_del_root(trans, tree_root, &root->root_key);
 824         BUG_ON(ret);
 825
 826         nr = trans->blocks_used;
 827         ret = btrfs_end_transaction(trans, tree_root);
 828         BUG_ON(ret);
 829
 830         free_extent_buffer(root->node);
 831         free_extent_buffer(root->commit_root);
 832         kfree(root);
 833
 834         btrfs_btree_balance_dirty(tree_root, nr);
 835         return ret;
 836 }
 837 #endif
 838
 839 /*
 840  * new snapshots need to be created at a very specific time in the
 841  * transaction commit.  This does the actual creation
 842  */
 843 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 844                                    struct btrfs_fs_info *fs_info,
 845                                    struct btrfs_pending_snapshot *pending)
 846 {
 847         struct btrfs_key key;
 848         struct btrfs_root_item *new_root_item;
 849         struct btrfs_root *tree_root = fs_info->tree_root;
 850         struct btrfs_root *root = pending->root;
 851         struct btrfs_root *parent_root;
 852         struct inode *parent_inode;
 853         struct dentry *dentry;
 854         struct extent_buffer *tmp;
 855         struct extent_buffer *old;
 856         int ret;
 857         u64 to_reserve = 0;
 858         u64 index = 0;
 859         u64 objectid;
 860
 861         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 862         if (!new_root_item) {
 863                 pending->error = -ENOMEM;
 864                 goto fail;
 865         }
 866
 867         ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
 868         if (ret) {
 869                 pending->error = ret;
 870                 goto fail;
 871         }
 872
 873         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
 874         btrfs_orphan_pre_snapshot(trans, pending, &to_reserve);
 875
 876         if (to_reserve > 0) {
 877                 ret = btrfs_block_rsv_add(trans, root, &pending->block_rsv,
 878                                           to_reserve);
 879                 if (ret) {
 880                         pending->error = ret;
 881                         goto fail;
 882                 }
 883         }
 884
 885         key.objectid = objectid;
 886         key.offset = (u64)-1;
 887         key.type = BTRFS_ROOT_ITEM_KEY;
 888
 889         trans->block_rsv = &pending->block_rsv;
 890
 891         dentry = pending->dentry;
 892         parent_inode = dentry->d_parent->d_inode;
 893         parent_root = BTRFS_I(parent_inode)->root;
 894         record_root_in_trans(trans, parent_root);
 895
 896         /*
 897          * insert the directory item
 898          */
 899         ret = btrfs_set_inode_index(parent_inode, &index);
 900         BUG_ON(ret);
 901         ret = btrfs_insert_dir_item(trans, parent_root,
 902                                 dentry->d_name.name, dentry->d_name.len,
 903                                 parent_inode->i_ino, &key,
 904                                 BTRFS_FT_DIR, index);
 905         BUG_ON(ret);
 906
 907         btrfs_i_size_write(parent_inode, parent_inode->i_size +
 908                                          dentry->d_name.len * 2);
 909         ret = btrfs_update_inode(trans, parent_root, parent_inode);
 910         BUG_ON(ret);
 911
 912         record_root_in_trans(trans, root);
 913         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
 914         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
 915
 916         old = btrfs_lock_root_node(root);
 917         btrfs_cow_block(trans, root, old, NULL, 0, &old);
 918         btrfs_set_lock_blocking(old);
 919
 920         btrfs_copy_root(trans, root, old, &tmp, objectid);
 921         btrfs_tree_unlock(old);
 922         free_extent_buffer(old);
 923
 924         btrfs_set_root_node(new_root_item, tmp);
 925         /* record when the snapshot was created in key.offset */
 926         key.offset = trans->transid;
 927         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
 928         btrfs_tree_unlock(tmp);
 929         free_extent_buffer(tmp);
 930         BUG_ON(ret);
 931
 932         /*
 933          * insert root back/forward references
 934          */
 935         ret = btrfs_add_root_ref(trans, tree_root, objectid,
 936                                  parent_root->root_key.objectid,
 937                                  parent_inode->i_ino, index,
 938                                  dentry->d_name.name, dentry->d_name.len);
 939         BUG_ON(ret);
 940
 941         key.offset = (u64)-1;
 942         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
 943         BUG_ON(IS_ERR(pending->snap));
 944
 945         btrfs_reloc_post_snapshot(trans, pending);
 946         btrfs_orphan_post_snapshot(trans, pending);
 947 fail:
 948         kfree(new_root_item);
 949         btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
 950         return 0;
 951 }
 952
 953 /*
 954  * create all the snapshots we've scheduled for creation
 955  */
 956 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
 957                                              struct btrfs_fs_info *fs_info)
 958 {
 959         struct btrfs_pending_snapshot *pending;
 960         struct list_head *head = &trans->transaction->pending_snapshots;
 961         int ret;
 962
 963         list_for_each_entry(pending, head, list) {
 964                 ret = create_pending_snapshot(trans, fs_info, pending);
 965                 BUG_ON(ret);
 966         }
 967         return 0;
 968 }
 969
 970 static void update_super_roots(struct btrfs_root *root)
 971 {
 972         struct btrfs_root_item *root_item;
 973         struct btrfs_super_block *super;
 974
 975         super = &root->fs_info->super_copy;
 976
 977         root_item = &root->fs_info->chunk_root->root_item;
 978         super->chunk_root = root_item->bytenr;
 979         super->chunk_root_generation = root_item->generation;
 980         super->chunk_root_level = root_item->level;
 981
 982         root_item = &root->fs_info->tree_root->root_item;
 983         super->root = root_item->bytenr;
 984         super->generation = root_item->generation;
 985         super->root_level = root_item->level;
 986         if (super->cache_generation != 0 || btrfs_test_opt(root, SPACE_CACHE))
 987                 super->cache_generation = root_item->generation;
 988 }
 989
 990 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
 991 {
 992         int ret = 0;
 993         spin_lock(&info->new_trans_lock);
 994         if (info->running_transaction)
 995                 ret = info->running_transaction->in_commit;
 996         spin_unlock(&info->new_trans_lock);
 997         return ret;
 998 }
 999
1000 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1001 {
1002         int ret = 0;
1003         spin_lock(&info->new_trans_lock);
1004         if (info->running_transaction)
1005                 ret = info->running_transaction->blocked;
1006         spin_unlock(&info->new_trans_lock);
1007         return ret;
1008 }
1009
1010 /*
1011  * wait for the current transaction commit to start and block subsequent
1012  * transaction joins
1013  */
1014 static void wait_current_trans_commit_start(struct btrfs_root *root,
1015                                             struct btrfs_transaction *trans)
1016 {
1017         DEFINE_WAIT(wait);
1018
1019         if (trans->in_commit)
1020                 return;
1021
1022         while (1) {
1023                 prepare_to_wait(&root->fs_info->transaction_blocked_wait, &wait,
1024                                 TASK_UNINTERRUPTIBLE);
1025                 if (trans->in_commit) {
1026                         finish_wait(&root->fs_info->transaction_blocked_wait,
1027                                     &wait);
1028                         break;
1029                 }
1030                 mutex_unlock(&root->fs_info->trans_mutex);
1031                 schedule();
1032                 mutex_lock(&root->fs_info->trans_mutex);
1033                 finish_wait(&root->fs_info->transaction_blocked_wait, &wait);
1034         }
1035 }
1036
1037 /*
1038  * wait for the current transaction to start and then become unblocked.
1039  * caller holds ref.
1040  */
1041 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1042                                          struct btrfs_transaction *trans)
1043 {
1044         DEFINE_WAIT(wait);
1045
1046         if (trans->commit_done || (trans->in_commit && !trans->blocked))
1047                 return;
1048
1049         while (1) {
1050                 prepare_to_wait(&root->fs_info->transaction_wait, &wait,
1051                                 TASK_UNINTERRUPTIBLE);
1052                 if (trans->commit_done ||
1053                     (trans->in_commit && !trans->blocked)) {
1054                         finish_wait(&root->fs_info->transaction_wait,
1055                                     &wait);
1056                         break;
1057                 }
1058                 mutex_unlock(&root->fs_info->trans_mutex);
1059                 schedule();
1060                 mutex_lock(&root->fs_info->trans_mutex);
1061                 finish_wait(&root->fs_info->transaction_wait,
1062                             &wait);
1063         }
1064 }
1065
1066 /*
1067  * commit transactions asynchronously. once btrfs_commit_transaction_async
1068  * returns, any subsequent transaction will not be allowed to join.
1069  */
1070 struct btrfs_async_commit {
1071         struct btrfs_trans_handle *newtrans;
1072         struct btrfs_root *root;
1073         struct delayed_work work;
1074 };
1075
1076 static void do_async_commit(struct work_struct *work)
1077 {
1078         struct btrfs_async_commit *ac =
1079                 container_of(work, struct btrfs_async_commit, work.work);
1080
1081         btrfs_commit_transaction(ac->newtrans, ac->root);
1082         kfree(ac);
1083 }
1084
1085 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1086                                    struct btrfs_root *root,
1087                                    int wait_for_unblock)
1088 {
1089         struct btrfs_async_commit *ac;
1090         struct btrfs_transaction *cur_trans;
1091
1092         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1093         BUG_ON(!ac);
1094
1095         INIT_DELAYED_WORK(&ac->work, do_async_commit);
1096         ac->root = root;
1097         ac->newtrans = btrfs_join_transaction(root, 0);
1098
1099         /* take transaction reference */
1100         mutex_lock(&root->fs_info->trans_mutex);
1101         cur_trans = trans->transaction;
1102         cur_trans->use_count++;
1103         mutex_unlock(&root->fs_info->trans_mutex);
1104
1105         btrfs_end_transaction(trans, root);
1106         schedule_delayed_work(&ac->work, 0);
1107
1108         /* wait for transaction to start and unblock */
1109         mutex_lock(&root->fs_info->trans_mutex);
1110         if (wait_for_unblock)
1111                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1112         else
1113                 wait_current_trans_commit_start(root, cur_trans);
1114         put_transaction(cur_trans);
1115         mutex_unlock(&root->fs_info->trans_mutex);
1116
1117         return 0;
1118 }
1119
1120 /*
1121  * btrfs_transaction state sequence:
1122  *    in_commit = 0, blocked = 0  (initial)
1123  *    in_commit = 1, blocked = 1
1124  *    blocked = 0
1125  *    commit_done = 1
1126  */
1127 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1128                              struct btrfs_root *root)
1129 {
1130         unsigned long joined = 0;
1131         struct btrfs_transaction *cur_trans;
1132         struct btrfs_transaction *prev_trans = NULL;
1133         DEFINE_WAIT(wait);
1134         int ret;
1135         int should_grow = 0;
1136         unsigned long now = get_seconds();
1137         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1138
1139         btrfs_run_ordered_operations(root, 0);
1140
1141         /* make a pass through all the delayed refs we have so far
1142          * any runnings procs may add more while we are here
1143          */
1144         ret = btrfs_run_delayed_refs(trans, root, 0);
1145         BUG_ON(ret);
1146
1147         btrfs_trans_release_metadata(trans, root);
1148
1149         cur_trans = trans->transaction;
1150         /*
1151          * set the flushing flag so procs in this transaction have to
1152          * start sending their work down.
1153          */
1154         cur_trans->delayed_refs.flushing = 1;
1155
1156         ret = btrfs_run_delayed_refs(trans, root, 0);
1157         BUG_ON(ret);
1158
1159         mutex_lock(&root->fs_info->trans_mutex);
1160         if (cur_trans->in_commit) {
1161                 cur_trans->use_count++;
1162                 mutex_unlock(&root->fs_info->trans_mutex);
1163                 btrfs_end_transaction(trans, root);
1164
1165                 ret = wait_for_commit(root, cur_trans);
1166                 BUG_ON(ret);
1167
1168                 mutex_lock(&root->fs_info->trans_mutex);
1169                 put_transaction(cur_trans);
1170                 mutex_unlock(&root->fs_info->trans_mutex);
1171
1172                 return 0;
1173         }
1174
1175         trans->transaction->in_commit = 1;
1176         trans->transaction->blocked = 1;
1177         wake_up(&root->fs_info->transaction_blocked_wait);
1178
1179         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1180                 prev_trans = list_entry(cur_trans->list.prev,
1181                                         struct btrfs_transaction, list);
1182                 if (!prev_trans->commit_done) {
1183                         prev_trans->use_count++;
1184                         mutex_unlock(&root->fs_info->trans_mutex);
1185
1186                         wait_for_commit(root, prev_trans);
1187
1188                         mutex_lock(&root->fs_info->trans_mutex);
1189                         put_transaction(prev_trans);
1190                 }
1191         }
1192
1193         if (now < cur_trans->start_time || now - cur_trans->start_time < 1)
1194                 should_grow = 1;
1195
1196         do {
1197                 int snap_pending = 0;
1198                 joined = cur_trans->num_joined;
1199                 if (!list_empty(&trans->transaction->pending_snapshots))
1200                         snap_pending = 1;
1201
1202                 WARN_ON(cur_trans != trans->transaction);
1203                 mutex_unlock(&root->fs_info->trans_mutex);
1204
1205                 if (flush_on_commit || snap_pending) {
1206                         btrfs_start_delalloc_inodes(root, 1);
1207                         ret = btrfs_wait_ordered_extents(root, 0, 1);
1208                         BUG_ON(ret);
1209                 }
1210
1211                 /*
1212                  * rename don't use btrfs_join_transaction, so, once we
1213                  * set the transaction to blocked above, we aren't going
1214                  * to get any new ordered operations.  We can safely run
1215                  * it here and no for sure that nothing new will be added
1216                  * to the list
1217                  */
1218                 btrfs_run_ordered_operations(root, 1);
1219
1220                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1221                                 TASK_UNINTERRUPTIBLE);
1222
1223                 smp_mb();
1224                 if (cur_trans->num_writers > 1)
1225                         schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1226                 else if (should_grow)
1227                         schedule_timeout(1);
1228
1229                 mutex_lock(&root->fs_info->trans_mutex);
1230                 finish_wait(&cur_trans->writer_wait, &wait);
1231         } while (cur_trans->num_writers > 1 ||
1232                  (should_grow && cur_trans->num_joined != joined));
1233
1234         ret = create_pending_snapshots(trans, root->fs_info);
1235         BUG_ON(ret);
1236
1237         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1238         BUG_ON(ret);
1239
1240         WARN_ON(cur_trans != trans->transaction);
1241
1242         /* btrfs_commit_tree_roots is responsible for getting the
1243          * various roots consistent with each other.  Every pointer
1244          * in the tree of tree roots has to point to the most up to date
1245          * root for every subvolume and other tree.  So, we have to keep
1246          * the tree logging code from jumping in and changing any
1247          * of the trees.
1248          *
1249          * At this point in the commit, there can't be any tree-log
1250          * writers, but a little lower down we drop the trans mutex
1251          * and let new people in.  By holding the tree_log_mutex
1252          * from now until after the super is written, we avoid races
1253          * with the tree-log code.
1254          */
1255         mutex_lock(&root->fs_info->tree_log_mutex);
1256
1257         ret = commit_fs_roots(trans, root);
1258         BUG_ON(ret);
1259
1260         /* commit_fs_roots gets rid of all the tree log roots, it is now
1261          * safe to free the root of tree log roots
1262          */
1263         btrfs_free_log_root_tree(trans, root->fs_info);
1264
1265         ret = commit_cowonly_roots(trans, root);
1266         BUG_ON(ret);
1267
1268         btrfs_prepare_extent_commit(trans, root);
1269
1270         cur_trans = root->fs_info->running_transaction;
1271         spin_lock(&root->fs_info->new_trans_lock);
1272         root->fs_info->running_transaction = NULL;
1273         spin_unlock(&root->fs_info->new_trans_lock);
1274
1275         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1276                             root->fs_info->tree_root->node);
1277         switch_commit_root(root->fs_info->tree_root);
1278
1279         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1280                             root->fs_info->chunk_root->node);
1281         switch_commit_root(root->fs_info->chunk_root);
1282
1283         update_super_roots(root);
1284
1285         if (!root->fs_info->log_root_recovering) {
1286                 btrfs_set_super_log_root(&root->fs_info->super_copy, 0);
1287                 btrfs_set_super_log_root_level(&root->fs_info->super_copy, 0);
1288         }
1289
1290         memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
1291                sizeof(root->fs_info->super_copy));
1292
1293         trans->transaction->blocked = 0;
1294
1295         wake_up(&root->fs_info->transaction_wait);
1296
1297         mutex_unlock(&root->fs_info->trans_mutex);
1298         ret = btrfs_write_and_wait_transaction(trans, root);
1299         BUG_ON(ret);
1300         write_ctree_super(trans, root, 0);
1301
1302         /*
1303          * the super is written, we can safely allow the tree-loggers
1304          * to go about their business
1305          */
1306         mutex_unlock(&root->fs_info->tree_log_mutex);
1307
1308         btrfs_finish_extent_commit(trans, root);
1309
1310         mutex_lock(&root->fs_info->trans_mutex);
1311
1312         cur_trans->commit_done = 1;
1313
1314         root->fs_info->last_trans_committed = cur_trans->transid;
1315
1316         wake_up(&cur_trans->commit_wait);
1317
1318         put_transaction(cur_trans);
1319         put_transaction(cur_trans);
1320
1321         mutex_unlock(&root->fs_info->trans_mutex);
1322
1323         if (current->journal_info == trans)
1324                 current->journal_info = NULL;
1325
1326         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1327
1328         if (current != root->fs_info->transaction_kthread)
1329                 btrfs_run_delayed_iputs(root);
1330
1331         return ret;
1332 }
1333
1334 /*
1335  * interface function to delete all the snapshots we have scheduled for deletion
1336  */
1337 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1338 {
1339         LIST_HEAD(list);
1340         struct btrfs_fs_info *fs_info = root->fs_info;
1341
1342         mutex_lock(&fs_info->trans_mutex);
1343         list_splice_init(&fs_info->dead_roots, &list);
1344         mutex_unlock(&fs_info->trans_mutex);
1345
1346         while (!list_empty(&list)) {
1347                 root = list_entry(list.next, struct btrfs_root, root_list);
1348                 list_del(&root->root_list);
1349
1350                 if (btrfs_header_backref_rev(root->node) <
1351                     BTRFS_MIXED_BACKREF_REV)
1352                         btrfs_drop_snapshot(root, NULL, 0);
1353                 else
1354                         btrfs_drop_snapshot(root, NULL, 1);
1355         }
1356         return 0;
1357 }