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 <linux/uuid.h>
  26 #include "ctree.h"
  27 #include "disk-io.h"
  28 #include "transaction.h"
  29 #include "locking.h"
  30 #include "tree-log.h"
  31 #include "inode-map.h"
  32 #include "volumes.h"
  33 #include "dev-replace.h"
  34
  35 #define BTRFS_ROOT_TRANS_TAG 0
  36
  37 static unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {
  38         [TRANS_STATE_RUNNING]           = 0U,
  39         [TRANS_STATE_BLOCKED]           = (__TRANS_USERSPACE |
  40                                            __TRANS_START),
  41         [TRANS_STATE_COMMIT_START]      = (__TRANS_USERSPACE |
  42                                            __TRANS_START |
  43                                            __TRANS_ATTACH),
  44         [TRANS_STATE_COMMIT_DOING]      = (__TRANS_USERSPACE |
  45                                            __TRANS_START |
  46                                            __TRANS_ATTACH |
  47                                            __TRANS_JOIN),
  48         [TRANS_STATE_UNBLOCKED]         = (__TRANS_USERSPACE |
  49                                            __TRANS_START |
  50                                            __TRANS_ATTACH |
  51                                            __TRANS_JOIN |
  52                                            __TRANS_JOIN_NOLOCK),
  53         [TRANS_STATE_COMPLETED]         = (__TRANS_USERSPACE |
  54                                            __TRANS_START |
  55                                            __TRANS_ATTACH |
  56                                            __TRANS_JOIN |
  57                                            __TRANS_JOIN_NOLOCK),
  58 };
  59
  60 static void put_transaction(struct btrfs_transaction *transaction)
  61 {
  62         WARN_ON(atomic_read(&transaction->use_count) == 0);
  63         if (atomic_dec_and_test(&transaction->use_count)) {
  64                 BUG_ON(!list_empty(&transaction->list));
  65                 WARN_ON(transaction->delayed_refs.root.rb_node);
  66                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  67         }
  68 }
  69
  70 static noinline void switch_commit_root(struct btrfs_root *root)
  71 {
  72         free_extent_buffer(root->commit_root);
  73         root->commit_root = btrfs_root_node(root);
  74 }
  75
  76 static inline void extwriter_counter_inc(struct btrfs_transaction *trans,
  77                                          unsigned int type)
  78 {
  79         if (type & TRANS_EXTWRITERS)
  80                 atomic_inc(&trans->num_extwriters);
  81 }
  82
  83 static inline void extwriter_counter_dec(struct btrfs_transaction *trans,
  84                                          unsigned int type)
  85 {
  86         if (type & TRANS_EXTWRITERS)
  87                 atomic_dec(&trans->num_extwriters);
  88 }
  89
  90 static inline void extwriter_counter_init(struct btrfs_transaction *trans,
  91                                           unsigned int type)
  92 {
  93         atomic_set(&trans->num_extwriters, ((type & TRANS_EXTWRITERS) ? 1 : 0));
  94 }
  95
  96 static inline int extwriter_counter_read(struct btrfs_transaction *trans)
  97 {
  98         return atomic_read(&trans->num_extwriters);
  99 }
 100
 101 /*
 102  * either allocate a new transaction or hop into the existing one
 103  */
 104 static noinline int join_transaction(struct btrfs_root *root, unsigned int type)
 105 {
 106         struct btrfs_transaction *cur_trans;
 107         struct btrfs_fs_info *fs_info = root->fs_info;
 108
 109         spin_lock(&fs_info->trans_lock);
 110 loop:
 111         /* The file system has been taken offline. No new transactions. */
 112         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 113                 spin_unlock(&fs_info->trans_lock);
 114                 return -EROFS;
 115         }
 116
 117         cur_trans = fs_info->running_transaction;
 118         if (cur_trans) {
 119                 if (cur_trans->aborted) {
 120                         spin_unlock(&fs_info->trans_lock);
 121                         return cur_trans->aborted;
 122                 }
 123                 if (btrfs_blocked_trans_types[cur_trans->state] & type) {
 124                         spin_unlock(&fs_info->trans_lock);
 125                         return -EBUSY;
 126                 }
 127                 atomic_inc(&cur_trans->use_count);
 128                 atomic_inc(&cur_trans->num_writers);
 129                 extwriter_counter_inc(cur_trans, type);
 130                 spin_unlock(&fs_info->trans_lock);
 131                 return 0;
 132         }
 133         spin_unlock(&fs_info->trans_lock);
 134
 135         /*
 136          * If we are ATTACH, we just want to catch the current transaction,
 137          * and commit it. If there is no transaction, just return ENOENT.
 138          */
 139         if (type == TRANS_ATTACH)
 140                 return -ENOENT;
 141
 142         /*
 143          * JOIN_NOLOCK only happens during the transaction commit, so
 144          * it is impossible that ->running_transaction is NULL
 145          */
 146         BUG_ON(type == TRANS_JOIN_NOLOCK);
 147
 148         cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
 149         if (!cur_trans)
 150                 return -ENOMEM;
 151
 152         spin_lock(&fs_info->trans_lock);
 153         if (fs_info->running_transaction) {
 154                 /*
 155                  * someone started a transaction after we unlocked.  Make sure
 156                  * to redo the checks above
 157                  */
 158                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 159                 goto loop;
 160         } else if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 161                 spin_unlock(&fs_info->trans_lock);
 162                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 163                 return -EROFS;
 164         }
 165
 166         atomic_set(&cur_trans->num_writers, 1);
 167         extwriter_counter_init(cur_trans, type);
 168         init_waitqueue_head(&cur_trans->writer_wait);
 169         init_waitqueue_head(&cur_trans->commit_wait);
 170         cur_trans->state = TRANS_STATE_RUNNING;
 171         /*
 172          * One for this trans handle, one so it will live on until we
 173          * commit the transaction.
 174          */
 175         atomic_set(&cur_trans->use_count, 2);
 176         cur_trans->start_time = get_seconds();
 177
 178         cur_trans->delayed_refs.root = RB_ROOT;
 179         cur_trans->delayed_refs.num_entries = 0;
 180         cur_trans->delayed_refs.num_heads_ready = 0;
 181         cur_trans->delayed_refs.num_heads = 0;
 182         cur_trans->delayed_refs.flushing = 0;
 183         cur_trans->delayed_refs.run_delayed_start = 0;
 184
 185         /*
 186          * although the tree mod log is per file system and not per transaction,
 187          * the log must never go across transaction boundaries.
 188          */
 189         smp_mb();
 190         if (!list_empty(&fs_info->tree_mod_seq_list))
 191                 WARN(1, KERN_ERR "btrfs: tree_mod_seq_list not empty when "
 192                         "creating a fresh transaction\n");
 193         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log))
 194                 WARN(1, KERN_ERR "btrfs: tree_mod_log rb tree not empty when "
 195                         "creating a fresh transaction\n");
 196         atomic64_set(&fs_info->tree_mod_seq, 0);
 197
 198         spin_lock_init(&cur_trans->delayed_refs.lock);
 199         atomic_set(&cur_trans->delayed_refs.procs_running_refs, 0);
 200         atomic_set(&cur_trans->delayed_refs.ref_seq, 0);
 201         init_waitqueue_head(&cur_trans->delayed_refs.wait);
 202
 203         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 204         INIT_LIST_HEAD(&cur_trans->ordered_operations);
 205         list_add_tail(&cur_trans->list, &fs_info->trans_list);
 206         extent_io_tree_init(&cur_trans->dirty_pages,
 207                              fs_info->btree_inode->i_mapping);
 208         fs_info->generation++;
 209         cur_trans->transid = fs_info->generation;
 210         fs_info->running_transaction = cur_trans;
 211         cur_trans->aborted = 0;
 212         spin_unlock(&fs_info->trans_lock);
 213
 214         return 0;
 215 }
 216
 217 /*
 218  * this does all the record keeping required to make sure that a reference
 219  * counted root is properly recorded in a given transaction.  This is required
 220  * to make sure the old root from before we joined the transaction is deleted
 221  * when the transaction commits
 222  */
 223 static int record_root_in_trans(struct btrfs_trans_handle *trans,
 224                                struct btrfs_root *root)
 225 {
 226         if (root->ref_cows && root->last_trans < trans->transid) {
 227                 WARN_ON(root == root->fs_info->extent_root);
 228                 WARN_ON(root->commit_root != root->node);
 229
 230                 /*
 231                  * see below for in_trans_setup usage rules
 232                  * we have the reloc mutex held now, so there
 233                  * is only one writer in this function
 234                  */
 235                 root->in_trans_setup = 1;
 236
 237                 /* make sure readers find in_trans_setup before
 238                  * they find our root->last_trans update
 239                  */
 240                 smp_wmb();
 241
 242                 spin_lock(&root->fs_info->fs_roots_radix_lock);
 243                 if (root->last_trans == trans->transid) {
 244                         spin_unlock(&root->fs_info->fs_roots_radix_lock);
 245                         return 0;
 246                 }
 247                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 248                            (unsigned long)root->root_key.objectid,
 249                            BTRFS_ROOT_TRANS_TAG);
 250                 spin_unlock(&root->fs_info->fs_roots_radix_lock);
 251                 root->last_trans = trans->transid;
 252
 253                 /* this is pretty tricky.  We don't want to
 254                  * take the relocation lock in btrfs_record_root_in_trans
 255                  * unless we're really doing the first setup for this root in
 256                  * this transaction.
 257                  *
 258                  * Normally we'd use root->last_trans as a flag to decide
 259                  * if we want to take the expensive mutex.
 260                  *
 261                  * But, we have to set root->last_trans before we
 262                  * init the relocation root, otherwise, we trip over warnings
 263                  * in ctree.c.  The solution used here is to flag ourselves
 264                  * with root->in_trans_setup.  When this is 1, we're still
 265                  * fixing up the reloc trees and everyone must wait.
 266                  *
 267                  * When this is zero, they can trust root->last_trans and fly
 268                  * through btrfs_record_root_in_trans without having to take the
 269                  * lock.  smp_wmb() makes sure that all the writes above are
 270                  * done before we pop in the zero below
 271                  */
 272                 btrfs_init_reloc_root(trans, root);
 273                 smp_wmb();
 274                 root->in_trans_setup = 0;
 275         }
 276         return 0;
 277 }
 278
 279
 280 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 281                                struct btrfs_root *root)
 282 {
 283         if (!root->ref_cows)
 284                 return 0;
 285
 286         /*
 287          * see record_root_in_trans for comments about in_trans_setup usage
 288          * and barriers
 289          */
 290         smp_rmb();
 291         if (root->last_trans == trans->transid &&
 292             !root->in_trans_setup)
 293                 return 0;
 294
 295         mutex_lock(&root->fs_info->reloc_mutex);
 296         record_root_in_trans(trans, root);
 297         mutex_unlock(&root->fs_info->reloc_mutex);
 298
 299         return 0;
 300 }
 301
 302 static inline int is_transaction_blocked(struct btrfs_transaction *trans)
 303 {
 304         return (trans->state >= TRANS_STATE_BLOCKED &&
 305                 trans->state < TRANS_STATE_UNBLOCKED &&
 306                 !trans->aborted);
 307 }
 308
 309 /* wait for commit against the current transaction to become unblocked
 310  * when this is done, it is safe to start a new transaction, but the current
 311  * transaction might not be fully on disk.
 312  */
 313 static void wait_current_trans(struct btrfs_root *root)
 314 {
 315         struct btrfs_transaction *cur_trans;
 316
 317         spin_lock(&root->fs_info->trans_lock);
 318         cur_trans = root->fs_info->running_transaction;
 319         if (cur_trans && is_transaction_blocked(cur_trans)) {
 320                 atomic_inc(&cur_trans->use_count);
 321                 spin_unlock(&root->fs_info->trans_lock);
 322
 323                 wait_event(root->fs_info->transaction_wait,
 324                            cur_trans->state >= TRANS_STATE_UNBLOCKED ||
 325                            cur_trans->aborted);
 326                 put_transaction(cur_trans);
 327         } else {
 328                 spin_unlock(&root->fs_info->trans_lock);
 329         }
 330 }
 331
 332 static int may_wait_transaction(struct btrfs_root *root, int type)
 333 {
 334         if (root->fs_info->log_root_recovering)
 335                 return 0;
 336
 337         if (type == TRANS_USERSPACE)
 338                 return 1;
 339
 340         if (type == TRANS_START &&
 341             !atomic_read(&root->fs_info->open_ioctl_trans))
 342                 return 1;
 343
 344         return 0;
 345 }
 346
 347 static struct btrfs_trans_handle *
 348 start_transaction(struct btrfs_root *root, u64 num_items, unsigned int type,
 349                   enum btrfs_reserve_flush_enum flush)
 350 {
 351         struct btrfs_trans_handle *h;
 352         struct btrfs_transaction *cur_trans;
 353         u64 num_bytes = 0;
 354         int ret;
 355         u64 qgroup_reserved = 0;
 356
 357         if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state))
 358                 return ERR_PTR(-EROFS);
 359
 360         if (current->journal_info) {
 361                 WARN_ON(type & TRANS_EXTWRITERS);
 362                 h = current->journal_info;
 363                 h->use_count++;
 364                 WARN_ON(h->use_count > 2);
 365                 h->orig_rsv = h->block_rsv;
 366                 h->block_rsv = NULL;
 367                 goto got_it;
 368         }
 369
 370         /*
 371          * Do the reservation before we join the transaction so we can do all
 372          * the appropriate flushing if need be.
 373          */
 374         if (num_items > 0 && root != root->fs_info->chunk_root) {
 375                 if (root->fs_info->quota_enabled &&
 376                     is_fstree(root->root_key.objectid)) {
 377                         qgroup_reserved = num_items * root->leafsize;
 378                         ret = btrfs_qgroup_reserve(root, qgroup_reserved);
 379                         if (ret)
 380                                 return ERR_PTR(ret);
 381                 }
 382
 383                 num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
 384                 ret = btrfs_block_rsv_add(root,
 385                                           &root->fs_info->trans_block_rsv,
 386                                           num_bytes, flush);
 387                 if (ret)
 388                         goto reserve_fail;
 389         }
 390 again:
 391         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 392         if (!h) {
 393                 ret = -ENOMEM;
 394                 goto alloc_fail;
 395         }
 396
 397         /*
 398          * If we are JOIN_NOLOCK we're already committing a transaction and
 399          * waiting on this guy, so we don't need to do the sb_start_intwrite
 400          * because we're already holding a ref.  We need this because we could
 401          * have raced in and did an fsync() on a file which can kick a commit
 402          * and then we deadlock with somebody doing a freeze.
 403          *
 404          * If we are ATTACH, it means we just want to catch the current
 405          * transaction and commit it, so we needn't do sb_start_intwrite().
 406          */
 407         if (type & __TRANS_FREEZABLE)
 408                 sb_start_intwrite(root->fs_info->sb);
 409
 410         if (may_wait_transaction(root, type))
 411                 wait_current_trans(root);
 412
 413         do {
 414                 ret = join_transaction(root, type);
 415                 if (ret == -EBUSY) {
 416                         wait_current_trans(root);
 417                         if (unlikely(type == TRANS_ATTACH))
 418                                 ret = -ENOENT;
 419                 }
 420         } while (ret == -EBUSY);
 421
 422         if (ret < 0) {
 423                 /* We must get the transaction if we are JOIN_NOLOCK. */
 424                 BUG_ON(type == TRANS_JOIN_NOLOCK);
 425                 goto join_fail;
 426         }
 427
 428         cur_trans = root->fs_info->running_transaction;
 429
 430         h->transid = cur_trans->transid;
 431         h->transaction = cur_trans;
 432         h->blocks_used = 0;
 433         h->bytes_reserved = 0;
 434         h->root = root;
 435         h->delayed_ref_updates = 0;
 436         h->use_count = 1;
 437         h->adding_csums = 0;
 438         h->block_rsv = NULL;
 439         h->orig_rsv = NULL;
 440         h->aborted = 0;
 441         h->qgroup_reserved = 0;
 442         h->delayed_ref_elem.seq = 0;
 443         h->type = type;
 444         h->allocating_chunk = false;
 445         INIT_LIST_HEAD(&h->qgroup_ref_list);
 446         INIT_LIST_HEAD(&h->new_bgs);
 447
 448         smp_mb();
 449         if (cur_trans->state >= TRANS_STATE_BLOCKED &&
 450             may_wait_transaction(root, type)) {
 451                 btrfs_commit_transaction(h, root);
 452                 goto again;
 453         }
 454
 455         if (num_bytes) {
 456                 trace_btrfs_space_reservation(root->fs_info, "transaction",
 457                                               h->transid, num_bytes, 1);
 458                 h->block_rsv = &root->fs_info->trans_block_rsv;
 459                 h->bytes_reserved = num_bytes;
 460         }
 461         h->qgroup_reserved = qgroup_reserved;
 462
 463 got_it:
 464         btrfs_record_root_in_trans(h, root);
 465
 466         if (!current->journal_info && type != TRANS_USERSPACE)
 467                 current->journal_info = h;
 468         return h;
 469
 470 join_fail:
 471         if (type & __TRANS_FREEZABLE)
 472                 sb_end_intwrite(root->fs_info->sb);
 473         kmem_cache_free(btrfs_trans_handle_cachep, h);
 474 alloc_fail:
 475         if (num_bytes)
 476                 btrfs_block_rsv_release(root, &root->fs_info->trans_block_rsv,
 477                                         num_bytes);
 478 reserve_fail:
 479         if (qgroup_reserved)
 480                 btrfs_qgroup_free(root, qgroup_reserved);
 481         return ERR_PTR(ret);
 482 }
 483
 484 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 485                                                    int num_items)
 486 {
 487         return start_transaction(root, num_items, TRANS_START,
 488                                  BTRFS_RESERVE_FLUSH_ALL);
 489 }
 490
 491 struct btrfs_trans_handle *btrfs_start_transaction_lflush(
 492                                         struct btrfs_root *root, int num_items)
 493 {
 494         return start_transaction(root, num_items, TRANS_START,
 495                                  BTRFS_RESERVE_FLUSH_LIMIT);
 496 }
 497
 498 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 499 {
 500         return start_transaction(root, 0, TRANS_JOIN, 0);
 501 }
 502
 503 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
 504 {
 505         return start_transaction(root, 0, TRANS_JOIN_NOLOCK, 0);
 506 }
 507
 508 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 509 {
 510         return start_transaction(root, 0, TRANS_USERSPACE, 0);
 511 }
 512
 513 /*
 514  * btrfs_attach_transaction() - catch the running transaction
 515  *
 516  * It is used when we want to commit the current the transaction, but
 517  * don't want to start a new one.
 518  *
 519  * Note: If this function return -ENOENT, it just means there is no
 520  * running transaction. But it is possible that the inactive transaction
 521  * is still in the memory, not fully on disk. If you hope there is no
 522  * inactive transaction in the fs when -ENOENT is returned, you should
 523  * invoke
 524  *     btrfs_attach_transaction_barrier()
 525  */
 526 struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
 527 {
 528         return start_transaction(root, 0, TRANS_ATTACH, 0);
 529 }
 530
 531 /*
 532  * btrfs_attach_transaction_barrier() - catch the running transaction
 533  *
 534  * It is similar to the above function, the differentia is this one
 535  * will wait for all the inactive transactions until they fully
 536  * complete.
 537  */
 538 struct btrfs_trans_handle *
 539 btrfs_attach_transaction_barrier(struct btrfs_root *root)
 540 {
 541         struct btrfs_trans_handle *trans;
 542
 543         trans = start_transaction(root, 0, TRANS_ATTACH, 0);
 544         if (IS_ERR(trans) && PTR_ERR(trans) == -ENOENT)
 545                 btrfs_wait_for_commit(root, 0);
 546
 547         return trans;
 548 }
 549
 550 /* wait for a transaction commit to be fully complete */
 551 static noinline void wait_for_commit(struct btrfs_root *root,
 552                                     struct btrfs_transaction *commit)
 553 {
 554         wait_event(commit->commit_wait, commit->state == TRANS_STATE_COMPLETED);
 555 }
 556
 557 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 558 {
 559         struct btrfs_transaction *cur_trans = NULL, *t;
 560         int ret = 0;
 561
 562         if (transid) {
 563                 if (transid <= root->fs_info->last_trans_committed)
 564                         goto out;
 565
 566                 ret = -EINVAL;
 567                 /* find specified transaction */
 568                 spin_lock(&root->fs_info->trans_lock);
 569                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 570                         if (t->transid == transid) {
 571                                 cur_trans = t;
 572                                 atomic_inc(&cur_trans->use_count);
 573                                 ret = 0;
 574                                 break;
 575                         }
 576                         if (t->transid > transid) {
 577                                 ret = 0;
 578                                 break;
 579                         }
 580                 }
 581                 spin_unlock(&root->fs_info->trans_lock);
 582                 /* The specified transaction doesn't exist */
 583                 if (!cur_trans)
 584                         goto out;
 585         } else {
 586                 /* find newest transaction that is committing | committed */
 587                 spin_lock(&root->fs_info->trans_lock);
 588                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 589                                             list) {
 590                         if (t->state >= TRANS_STATE_COMMIT_START) {
 591                                 if (t->state == TRANS_STATE_COMPLETED)
 592                                         break;
 593                                 cur_trans = t;
 594                                 atomic_inc(&cur_trans->use_count);
 595                                 break;
 596                         }
 597                 }
 598                 spin_unlock(&root->fs_info->trans_lock);
 599                 if (!cur_trans)
 600                         goto out;  /* nothing committing|committed */
 601         }
 602
 603         wait_for_commit(root, cur_trans);
 604         put_transaction(cur_trans);
 605 out:
 606         return ret;
 607 }
 608
 609 void btrfs_throttle(struct btrfs_root *root)
 610 {
 611         if (!atomic_read(&root->fs_info->open_ioctl_trans))
 612                 wait_current_trans(root);
 613 }
 614
 615 static int should_end_transaction(struct btrfs_trans_handle *trans,
 616                                   struct btrfs_root *root)
 617 {
 618         if (root->fs_info->global_block_rsv.space_info->full &&
 619             btrfs_should_throttle_delayed_refs(trans, root))
 620                 return 1;
 621
 622         return !!btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
 623 }
 624
 625 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 626                                  struct btrfs_root *root)
 627 {
 628         struct btrfs_transaction *cur_trans = trans->transaction;
 629         int updates;
 630         int err;
 631
 632         smp_mb();
 633         if (cur_trans->state >= TRANS_STATE_BLOCKED ||
 634             cur_trans->delayed_refs.flushing)
 635                 return 1;
 636
 637         updates = trans->delayed_ref_updates;
 638         trans->delayed_ref_updates = 0;
 639         if (updates) {
 640                 err = btrfs_run_delayed_refs(trans, root, updates);
 641                 if (err) /* Error code will also eval true */
 642                         return err;
 643         }
 644
 645         return should_end_transaction(trans, root);
 646 }
 647
 648 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 649                           struct btrfs_root *root, int throttle)
 650 {
 651         struct btrfs_transaction *cur_trans = trans->transaction;
 652         struct btrfs_fs_info *info = root->fs_info;
 653         unsigned long cur = trans->delayed_ref_updates;
 654         int lock = (trans->type != TRANS_JOIN_NOLOCK);
 655         int err = 0;
 656
 657         if (--trans->use_count) {
 658                 trans->block_rsv = trans->orig_rsv;
 659                 return 0;
 660         }
 661
 662         /*
 663          * do the qgroup accounting as early as possible
 664          */
 665         err = btrfs_delayed_refs_qgroup_accounting(trans, info);
 666
 667         btrfs_trans_release_metadata(trans, root);
 668         trans->block_rsv = NULL;
 669
 670         if (trans->qgroup_reserved) {
 671                 /*
 672                  * the same root has to be passed here between start_transaction
 673                  * and end_transaction. Subvolume quota depends on this.
 674                  */
 675                 btrfs_qgroup_free(trans->root, trans->qgroup_reserved);
 676                 trans->qgroup_reserved = 0;
 677         }
 678
 679         if (!list_empty(&trans->new_bgs))
 680                 btrfs_create_pending_block_groups(trans, root);
 681
 682         trans->delayed_ref_updates = 0;
 683         if (btrfs_should_throttle_delayed_refs(trans, root)) {
 684                 cur = max_t(unsigned long, cur, 1);
 685                 trans->delayed_ref_updates = 0;
 686                 btrfs_run_delayed_refs(trans, root, cur);
 687         }
 688
 689         btrfs_trans_release_metadata(trans, root);
 690         trans->block_rsv = NULL;
 691
 692         if (!list_empty(&trans->new_bgs))
 693                 btrfs_create_pending_block_groups(trans, root);
 694
 695         if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
 696             should_end_transaction(trans, root) &&
 697             ACCESS_ONCE(cur_trans->state) == TRANS_STATE_RUNNING) {
 698                 spin_lock(&info->trans_lock);
 699                 if (cur_trans->state == TRANS_STATE_RUNNING)
 700                         cur_trans->state = TRANS_STATE_BLOCKED;
 701                 spin_unlock(&info->trans_lock);
 702         }
 703
 704         if (lock && ACCESS_ONCE(cur_trans->state) == TRANS_STATE_BLOCKED) {
 705                 if (throttle) {
 706                         /*
 707                          * We may race with somebody else here so end up having
 708                          * to call end_transaction on ourselves again, so inc
 709                          * our use_count.
 710                          */
 711                         trans->use_count++;
 712                         return btrfs_commit_transaction(trans, root);
 713                 } else {
 714                         wake_up_process(info->transaction_kthread);
 715                 }
 716         }
 717
 718         if (trans->type & __TRANS_FREEZABLE)
 719                 sb_end_intwrite(root->fs_info->sb);
 720
 721         WARN_ON(cur_trans != info->running_transaction);
 722         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 723         atomic_dec(&cur_trans->num_writers);
 724         extwriter_counter_dec(cur_trans, trans->type);
 725
 726         smp_mb();
 727         if (waitqueue_active(&cur_trans->writer_wait))
 728                 wake_up(&cur_trans->writer_wait);
 729         put_transaction(cur_trans);
 730
 731         if (current->journal_info == trans)
 732                 current->journal_info = NULL;
 733
 734         if (throttle)
 735                 btrfs_run_delayed_iputs(root);
 736
 737         if (trans->aborted ||
 738             test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state))
 739                 err = -EIO;
 740         assert_qgroups_uptodate(trans);
 741
 742         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 743         return err;
 744 }
 745
 746 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 747                           struct btrfs_root *root)
 748 {
 749         return __btrfs_end_transaction(trans, root, 0);
 750 }
 751
 752 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 753                                    struct btrfs_root *root)
 754 {
 755         return __btrfs_end_transaction(trans, root, 1);
 756 }
 757
 758 int btrfs_end_transaction_dmeta(struct btrfs_trans_handle *trans,
 759                                 struct btrfs_root *root)
 760 {
 761         return __btrfs_end_transaction(trans, root, 1);
 762 }
 763
 764 /*
 765  * when btree blocks are allocated, they have some corresponding bits set for
 766  * them in one of two extent_io trees.  This is used to make sure all of
 767  * those extents are sent to disk but does not wait on them
 768  */
 769 int btrfs_write_marked_extents(struct btrfs_root *root,
 770                                struct extent_io_tree *dirty_pages, int mark)
 771 {
 772         int err = 0;
 773         int werr = 0;
 774         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 775         struct extent_state *cached_state = NULL;
 776         u64 start = 0;
 777         u64 end;
 778
 779         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 780                                       mark, &cached_state)) {
 781                 convert_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT,
 782                                    mark, &cached_state, GFP_NOFS);
 783                 cached_state = NULL;
 784                 err = filemap_fdatawrite_range(mapping, start, end);
 785                 if (err)
 786                         werr = err;
 787                 cond_resched();
 788                 start = end + 1;
 789         }
 790         if (err)
 791                 werr = err;
 792         return werr;
 793 }
 794
 795 /*
 796  * when btree blocks are allocated, they have some corresponding bits set for
 797  * them in one of two extent_io trees.  This is used to make sure all of
 798  * those extents are on disk for transaction or log commit.  We wait
 799  * on all the pages and clear them from the dirty pages state tree
 800  */
 801 int btrfs_wait_marked_extents(struct btrfs_root *root,
 802                               struct extent_io_tree *dirty_pages, int mark)
 803 {
 804         int err = 0;
 805         int werr = 0;
 806         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 807         struct extent_state *cached_state = NULL;
 808         u64 start = 0;
 809         u64 end;
 810
 811         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 812                                       EXTENT_NEED_WAIT, &cached_state)) {
 813                 clear_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT,
 814                                  0, 0, &cached_state, GFP_NOFS);
 815                 err = filemap_fdatawait_range(mapping, start, end);
 816                 if (err)
 817                         werr = err;
 818                 cond_resched();
 819                 start = end + 1;
 820         }
 821         if (err)
 822                 werr = err;
 823         return werr;
 824 }
 825
 826 /*
 827  * when btree blocks are allocated, they have some corresponding bits set for
 828  * them in one of two extent_io trees.  This is used to make sure all of
 829  * those extents are on disk for transaction or log commit
 830  */
 831 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 832                                 struct extent_io_tree *dirty_pages, int mark)
 833 {
 834         int ret;
 835         int ret2;
 836         struct blk_plug plug;
 837
 838         blk_start_plug(&plug);
 839         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 840         blk_finish_plug(&plug);
 841         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 842
 843         if (ret)
 844                 return ret;
 845         if (ret2)
 846                 return ret2;
 847         return 0;
 848 }
 849
 850 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 851                                      struct btrfs_root *root)
 852 {
 853         if (!trans || !trans->transaction) {
 854                 struct inode *btree_inode;
 855                 btree_inode = root->fs_info->btree_inode;
 856                 return filemap_write_and_wait(btree_inode->i_mapping);
 857         }
 858         return btrfs_write_and_wait_marked_extents(root,
 859                                            &trans->transaction->dirty_pages,
 860                                            EXTENT_DIRTY);
 861 }
 862
 863 /*
 864  * this is used to update the root pointer in the tree of tree roots.
 865  *
 866  * But, in the case of the extent allocation tree, updating the root
 867  * pointer may allocate blocks which may change the root of the extent
 868  * allocation tree.
 869  *
 870  * So, this loops and repeats and makes sure the cowonly root didn't
 871  * change while the root pointer was being updated in the metadata.
 872  */
 873 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 874                                struct btrfs_root *root)
 875 {
 876         int ret;
 877         u64 old_root_bytenr;
 878         u64 old_root_used;
 879         struct btrfs_root *tree_root = root->fs_info->tree_root;
 880
 881         old_root_used = btrfs_root_used(&root->root_item);
 882         btrfs_write_dirty_block_groups(trans, root);
 883
 884         while (1) {
 885                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 886                 if (old_root_bytenr == root->node->start &&
 887                     old_root_used == btrfs_root_used(&root->root_item))
 888                         break;
 889
 890                 btrfs_set_root_node(&root->root_item, root->node);
 891                 ret = btrfs_update_root(trans, tree_root,
 892                                         &root->root_key,
 893                                         &root->root_item);
 894                 if (ret)
 895                         return ret;
 896
 897                 old_root_used = btrfs_root_used(&root->root_item);
 898                 ret = btrfs_write_dirty_block_groups(trans, root);
 899                 if (ret)
 900                         return ret;
 901         }
 902
 903         if (root != root->fs_info->extent_root)
 904                 switch_commit_root(root);
 905
 906         return 0;
 907 }
 908
 909 /*
 910  * update all the cowonly tree roots on disk
 911  *
 912  * The error handling in this function may not be obvious. Any of the
 913  * failures will cause the file system to go offline. We still need
 914  * to clean up the delayed refs.
 915  */
 916 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 917                                          struct btrfs_root *root)
 918 {
 919         struct btrfs_fs_info *fs_info = root->fs_info;
 920         struct list_head *next;
 921         struct extent_buffer *eb;
 922         int ret;
 923
 924         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 925         if (ret)
 926                 return ret;
 927
 928         eb = btrfs_lock_root_node(fs_info->tree_root);
 929         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
 930                               0, &eb);
 931         btrfs_tree_unlock(eb);
 932         free_extent_buffer(eb);
 933
 934         if (ret)
 935                 return ret;
 936
 937         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 938         if (ret)
 939                 return ret;
 940
 941         ret = btrfs_run_dev_stats(trans, root->fs_info);
 942         WARN_ON(ret);
 943         ret = btrfs_run_dev_replace(trans, root->fs_info);
 944         WARN_ON(ret);
 945
 946         ret = btrfs_run_qgroups(trans, root->fs_info);
 947         BUG_ON(ret);
 948
 949         /* run_qgroups might have added some more refs */
 950         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 951         BUG_ON(ret);
 952
 953         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 954                 next = fs_info->dirty_cowonly_roots.next;
 955                 list_del_init(next);
 956                 root = list_entry(next, struct btrfs_root, dirty_list);
 957
 958                 ret = update_cowonly_root(trans, root);
 959                 if (ret)
 960                         return ret;
 961         }
 962
 963         down_write(&fs_info->extent_commit_sem);
 964         switch_commit_root(fs_info->extent_root);
 965         up_write(&fs_info->extent_commit_sem);
 966
 967         btrfs_after_dev_replace_commit(fs_info);
 968
 969         return 0;
 970 }
 971
 972 /*
 973  * dead roots are old snapshots that need to be deleted.  This allocates
 974  * a dirty root struct and adds it into the list of dead roots that need to
 975  * be deleted
 976  */
 977 int btrfs_add_dead_root(struct btrfs_root *root)
 978 {
 979         spin_lock(&root->fs_info->trans_lock);
 980         list_add_tail(&root->root_list, &root->fs_info->dead_roots);
 981         spin_unlock(&root->fs_info->trans_lock);
 982         return 0;
 983 }
 984
 985 /*
 986  * update all the cowonly tree roots on disk
 987  */
 988 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 989                                     struct btrfs_root *root)
 990 {
 991         struct btrfs_root *gang[8];
 992         struct btrfs_fs_info *fs_info = root->fs_info;
 993         int i;
 994         int ret;
 995         int err = 0;
 996
 997         spin_lock(&fs_info->fs_roots_radix_lock);
 998         while (1) {
 999                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
1000                                                  (void **)gang, 0,
1001                                                  ARRAY_SIZE(gang),
1002                                                  BTRFS_ROOT_TRANS_TAG);
1003                 if (ret == 0)
1004                         break;
1005                 for (i = 0; i < ret; i++) {
1006                         root = gang[i];
1007                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
1008                                         (unsigned long)root->root_key.objectid,
1009                                         BTRFS_ROOT_TRANS_TAG);
1010                         spin_unlock(&fs_info->fs_roots_radix_lock);
1011
1012                         btrfs_free_log(trans, root);
1013                         btrfs_update_reloc_root(trans, root);
1014                         btrfs_orphan_commit_root(trans, root);
1015
1016                         btrfs_save_ino_cache(root, trans);
1017
1018                         /* see comments in should_cow_block() */
1019                         root->force_cow = 0;
1020                         smp_wmb();
1021
1022                         if (root->commit_root != root->node) {
1023                                 mutex_lock(&root->fs_commit_mutex);
1024                                 switch_commit_root(root);
1025                                 btrfs_unpin_free_ino(root);
1026                                 mutex_unlock(&root->fs_commit_mutex);
1027
1028                                 btrfs_set_root_node(&root->root_item,
1029                                                     root->node);
1030                         }
1031
1032                         err = btrfs_update_root(trans, fs_info->tree_root,
1033                                                 &root->root_key,
1034                                                 &root->root_item);
1035                         spin_lock(&fs_info->fs_roots_radix_lock);
1036                         if (err)
1037                                 break;
1038                 }
1039         }
1040         spin_unlock(&fs_info->fs_roots_radix_lock);
1041         return err;
1042 }
1043
1044 /*
1045  * defrag a given btree.
1046  * Every leaf in the btree is read and defragged.
1047  */
1048 int btrfs_defrag_root(struct btrfs_root *root)
1049 {
1050         struct btrfs_fs_info *info = root->fs_info;
1051         struct btrfs_trans_handle *trans;
1052         int ret;
1053
1054         if (xchg(&root->defrag_running, 1))
1055                 return 0;
1056
1057         while (1) {
1058                 trans = btrfs_start_transaction(root, 0);
1059                 if (IS_ERR(trans))
1060                         return PTR_ERR(trans);
1061
1062                 ret = btrfs_defrag_leaves(trans, root);
1063
1064                 btrfs_end_transaction(trans, root);
1065                 btrfs_btree_balance_dirty(info->tree_root);
1066                 cond_resched();
1067
1068                 if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
1069                         break;
1070
1071                 if (btrfs_defrag_cancelled(root->fs_info)) {
1072                         printk(KERN_DEBUG "btrfs: defrag_root cancelled\n");
1073                         ret = -EAGAIN;
1074                         break;
1075                 }
1076         }
1077         root->defrag_running = 0;
1078         return ret;
1079 }
1080
1081 /*
1082  * new snapshots need to be created at a very specific time in the
1083  * transaction commit.  This does the actual creation.
1084  *
1085  * Note:
1086  * If the error which may affect the commitment of the current transaction
1087  * happens, we should return the error number. If the error which just affect
1088  * the creation of the pending snapshots, just return 0.
1089  */
1090 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
1091                                    struct btrfs_fs_info *fs_info,
1092                                    struct btrfs_pending_snapshot *pending)
1093 {
1094         struct btrfs_key key;
1095         struct btrfs_root_item *new_root_item;
1096         struct btrfs_root *tree_root = fs_info->tree_root;
1097         struct btrfs_root *root = pending->root;
1098         struct btrfs_root *parent_root;
1099         struct btrfs_block_rsv *rsv;
1100         struct inode *parent_inode;
1101         struct btrfs_path *path;
1102         struct btrfs_dir_item *dir_item;
1103         struct dentry *dentry;
1104         struct extent_buffer *tmp;
1105         struct extent_buffer *old;
1106         struct timespec cur_time = CURRENT_TIME;
1107         int ret = 0;
1108         u64 to_reserve = 0;
1109         u64 index = 0;
1110         u64 objectid;
1111         u64 root_flags;
1112         uuid_le new_uuid;
1113
1114         path = btrfs_alloc_path();
1115         if (!path) {
1116                 pending->error = -ENOMEM;
1117                 return 0;
1118         }
1119
1120         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
1121         if (!new_root_item) {
1122                 pending->error = -ENOMEM;
1123                 goto root_item_alloc_fail;
1124         }
1125
1126         pending->error = btrfs_find_free_objectid(tree_root, &objectid);
1127         if (pending->error)
1128                 goto no_free_objectid;
1129
1130         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
1131
1132         if (to_reserve > 0) {
1133                 pending->error = btrfs_block_rsv_add(root,
1134                                                      &pending->block_rsv,
1135                                                      to_reserve,
1136                                                      BTRFS_RESERVE_NO_FLUSH);
1137                 if (pending->error)
1138                         goto no_free_objectid;
1139         }
1140
1141         pending->error = btrfs_qgroup_inherit(trans, fs_info,
1142                                               root->root_key.objectid,
1143                                               objectid, pending->inherit);
1144         if (pending->error)
1145                 goto no_free_objectid;
1146
1147         key.objectid = objectid;
1148         key.offset = (u64)-1;
1149         key.type = BTRFS_ROOT_ITEM_KEY;
1150
1151         rsv = trans->block_rsv;
1152         trans->block_rsv = &pending->block_rsv;
1153         trans->bytes_reserved = trans->block_rsv->reserved;
1154
1155         dentry = pending->dentry;
1156         parent_inode = pending->dir;
1157         parent_root = BTRFS_I(parent_inode)->root;
1158         record_root_in_trans(trans, parent_root);
1159
1160         /*
1161          * insert the directory item
1162          */
1163         ret = btrfs_set_inode_index(parent_inode, &index);
1164         BUG_ON(ret); /* -ENOMEM */
1165
1166         /* check if there is a file/dir which has the same name. */
1167         dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1168                                          btrfs_ino(parent_inode),
1169                                          dentry->d_name.name,
1170                                          dentry->d_name.len, 0);
1171         if (dir_item != NULL && !IS_ERR(dir_item)) {
1172                 pending->error = -EEXIST;
1173                 goto dir_item_existed;
1174         } else if (IS_ERR(dir_item)) {
1175                 ret = PTR_ERR(dir_item);
1176                 btrfs_abort_transaction(trans, root, ret);
1177                 goto fail;
1178         }
1179         btrfs_release_path(path);
1180
1181         /*
1182          * pull in the delayed directory update
1183          * and the delayed inode item
1184          * otherwise we corrupt the FS during
1185          * snapshot
1186          */
1187         ret = btrfs_run_delayed_items(trans, root);
1188         if (ret) {      /* Transaction aborted */
1189                 btrfs_abort_transaction(trans, root, ret);
1190                 goto fail;
1191         }
1192
1193         record_root_in_trans(trans, root);
1194         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1195         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1196         btrfs_check_and_init_root_item(new_root_item);
1197
1198         root_flags = btrfs_root_flags(new_root_item);
1199         if (pending->readonly)
1200                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1201         else
1202                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1203         btrfs_set_root_flags(new_root_item, root_flags);
1204
1205         btrfs_set_root_generation_v2(new_root_item,
1206                         trans->transid);
1207         uuid_le_gen(&new_uuid);
1208         memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
1209         memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1210                         BTRFS_UUID_SIZE);
1211         if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
1212                 memset(new_root_item->received_uuid, 0,
1213                        sizeof(new_root_item->received_uuid));
1214                 memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1215                 memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1216                 btrfs_set_root_stransid(new_root_item, 0);
1217                 btrfs_set_root_rtransid(new_root_item, 0);
1218         }
1219         new_root_item->otime.sec = cpu_to_le64(cur_time.tv_sec);
1220         new_root_item->otime.nsec = cpu_to_le32(cur_time.tv_nsec);
1221         btrfs_set_root_otransid(new_root_item, trans->transid);
1222
1223         old = btrfs_lock_root_node(root);
1224         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1225         if (ret) {
1226                 btrfs_tree_unlock(old);
1227                 free_extent_buffer(old);
1228                 btrfs_abort_transaction(trans, root, ret);
1229                 goto fail;
1230         }
1231
1232         btrfs_set_lock_blocking(old);
1233
1234         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1235         /* clean up in any case */
1236         btrfs_tree_unlock(old);
1237         free_extent_buffer(old);
1238         if (ret) {
1239                 btrfs_abort_transaction(trans, root, ret);
1240                 goto fail;
1241         }
1242
1243         /* see comments in should_cow_block() */
1244         root->force_cow = 1;
1245         smp_wmb();
1246
1247         btrfs_set_root_node(new_root_item, tmp);
1248         /* record when the snapshot was created in key.offset */
1249         key.offset = trans->transid;
1250         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1251         btrfs_tree_unlock(tmp);
1252         free_extent_buffer(tmp);
1253         if (ret) {
1254                 btrfs_abort_transaction(trans, root, ret);
1255                 goto fail;
1256         }
1257
1258         /*
1259          * insert root back/forward references
1260          */
1261         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1262                                  parent_root->root_key.objectid,
1263                                  btrfs_ino(parent_inode), index,
1264                                  dentry->d_name.name, dentry->d_name.len);
1265         if (ret) {
1266                 btrfs_abort_transaction(trans, root, ret);
1267                 goto fail;
1268         }
1269
1270         key.offset = (u64)-1;
1271         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1272         if (IS_ERR(pending->snap)) {
1273                 ret = PTR_ERR(pending->snap);
1274                 btrfs_abort_transaction(trans, root, ret);
1275                 goto fail;
1276         }
1277
1278         ret = btrfs_reloc_post_snapshot(trans, pending);
1279         if (ret) {
1280                 btrfs_abort_transaction(trans, root, ret);
1281                 goto fail;
1282         }
1283
1284         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1285         if (ret) {
1286                 btrfs_abort_transaction(trans, root, ret);
1287                 goto fail;
1288         }
1289
1290         ret = btrfs_insert_dir_item(trans, parent_root,
1291                                     dentry->d_name.name, dentry->d_name.len,
1292                                     parent_inode, &key,
1293                                     BTRFS_FT_DIR, index);
1294         /* We have check then name at the beginning, so it is impossible. */
1295         BUG_ON(ret == -EEXIST || ret == -EOVERFLOW);
1296         if (ret) {
1297                 btrfs_abort_transaction(trans, root, ret);
1298                 goto fail;
1299         }
1300
1301         btrfs_i_size_write(parent_inode, parent_inode->i_size +
1302                                          dentry->d_name.len * 2);
1303         parent_inode->i_mtime = parent_inode->i_ctime = CURRENT_TIME;
1304         ret = btrfs_update_inode_fallback(trans, parent_root, parent_inode);
1305         if (ret)
1306                 btrfs_abort_transaction(trans, root, ret);
1307 fail:
1308         pending->error = ret;
1309 dir_item_existed:
1310         trans->block_rsv = rsv;
1311         trans->bytes_reserved = 0;
1312 no_free_objectid:
1313         kfree(new_root_item);
1314 root_item_alloc_fail:
1315         btrfs_free_path(path);
1316         return ret;
1317 }
1318
1319 /*
1320  * create all the snapshots we've scheduled for creation
1321  */
1322 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1323                                              struct btrfs_fs_info *fs_info)
1324 {
1325         struct btrfs_pending_snapshot *pending, *next;
1326         struct list_head *head = &trans->transaction->pending_snapshots;
1327         int ret = 0;
1328
1329         list_for_each_entry_safe(pending, next, head, list) {
1330                 list_del(&pending->list);
1331                 ret = create_pending_snapshot(trans, fs_info, pending);
1332                 if (ret)
1333                         break;
1334         }
1335         return ret;
1336 }
1337
1338 static void update_super_roots(struct btrfs_root *root)
1339 {
1340         struct btrfs_root_item *root_item;
1341         struct btrfs_super_block *super;
1342
1343         super = root->fs_info->super_copy;
1344
1345         root_item = &root->fs_info->chunk_root->root_item;
1346         super->chunk_root = root_item->bytenr;
1347         super->chunk_root_generation = root_item->generation;
1348         super->chunk_root_level = root_item->level;
1349
1350         root_item = &root->fs_info->tree_root->root_item;
1351         super->root = root_item->bytenr;
1352         super->generation = root_item->generation;
1353         super->root_level = root_item->level;
1354         if (btrfs_test_opt(root, SPACE_CACHE))
1355                 super->cache_generation = root_item->generation;
1356 }
1357
1358 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1359 {
1360         struct btrfs_transaction *trans;
1361         int ret = 0;
1362
1363         spin_lock(&info->trans_lock);
1364         trans = info->running_transaction;
1365         if (trans)
1366                 ret = (trans->state >= TRANS_STATE_COMMIT_START);
1367         spin_unlock(&info->trans_lock);
1368         return ret;
1369 }
1370
1371 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1372 {
1373         struct btrfs_transaction *trans;
1374         int ret = 0;
1375
1376         spin_lock(&info->trans_lock);
1377         trans = info->running_transaction;
1378         if (trans)
1379                 ret = is_transaction_blocked(trans);
1380         spin_unlock(&info->trans_lock);
1381         return ret;
1382 }
1383
1384 /*
1385  * wait for the current transaction commit to start and block subsequent
1386  * transaction joins
1387  */
1388 static void wait_current_trans_commit_start(struct btrfs_root *root,
1389                                             struct btrfs_transaction *trans)
1390 {
1391         wait_event(root->fs_info->transaction_blocked_wait,
1392                    trans->state >= TRANS_STATE_COMMIT_START ||
1393                    trans->aborted);
1394 }
1395
1396 /*
1397  * wait for the current transaction to start and then become unblocked.
1398  * caller holds ref.
1399  */
1400 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1401                                          struct btrfs_transaction *trans)
1402 {
1403         wait_event(root->fs_info->transaction_wait,
1404                    trans->state >= TRANS_STATE_UNBLOCKED ||
1405                    trans->aborted);
1406 }
1407
1408 /*
1409  * commit transactions asynchronously. once btrfs_commit_transaction_async
1410  * returns, any subsequent transaction will not be allowed to join.
1411  */
1412 struct btrfs_async_commit {
1413         struct btrfs_trans_handle *newtrans;
1414         struct btrfs_root *root;
1415         struct work_struct work;
1416 };
1417
1418 static void do_async_commit(struct work_struct *work)
1419 {
1420         struct btrfs_async_commit *ac =
1421                 container_of(work, struct btrfs_async_commit, work);
1422
1423         /*
1424          * We've got freeze protection passed with the transaction.
1425          * Tell lockdep about it.
1426          */
1427         if (ac->newtrans->type < TRANS_JOIN_NOLOCK)
1428                 rwsem_acquire_read(
1429                      &ac->root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1430                      0, 1, _THIS_IP_);
1431
1432         current->journal_info = ac->newtrans;
1433
1434         btrfs_commit_transaction(ac->newtrans, ac->root);
1435         kfree(ac);
1436 }
1437
1438 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1439                                    struct btrfs_root *root,
1440                                    int wait_for_unblock)
1441 {
1442         struct btrfs_async_commit *ac;
1443         struct btrfs_transaction *cur_trans;
1444
1445         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1446         if (!ac)
1447                 return -ENOMEM;
1448
1449         INIT_WORK(&ac->work, do_async_commit);
1450         ac->root = root;
1451         ac->newtrans = btrfs_join_transaction(root);
1452         if (IS_ERR(ac->newtrans)) {
1453                 int err = PTR_ERR(ac->newtrans);
1454                 kfree(ac);
1455                 return err;
1456         }
1457
1458         /* take transaction reference */
1459         cur_trans = trans->transaction;
1460         atomic_inc(&cur_trans->use_count);
1461
1462         btrfs_end_transaction(trans, root);
1463
1464         /*
1465          * Tell lockdep we've released the freeze rwsem, since the
1466          * async commit thread will be the one to unlock it.
1467          */
1468         if (trans->type < TRANS_JOIN_NOLOCK)
1469                 rwsem_release(
1470                         &root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1471                         1, _THIS_IP_);
1472
1473         schedule_work(&ac->work);
1474
1475         /* wait for transaction to start and unblock */
1476         if (wait_for_unblock)
1477                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1478         else
1479                 wait_current_trans_commit_start(root, cur_trans);
1480
1481         if (current->journal_info == trans)
1482                 current->journal_info = NULL;
1483
1484         put_transaction(cur_trans);
1485         return 0;
1486 }
1487
1488
1489 static void cleanup_transaction(struct btrfs_trans_handle *trans,
1490                                 struct btrfs_root *root, int err)
1491 {
1492         struct btrfs_transaction *cur_trans = trans->transaction;
1493         DEFINE_WAIT(wait);
1494
1495         WARN_ON(trans->use_count > 1);
1496
1497         btrfs_abort_transaction(trans, root, err);
1498
1499         spin_lock(&root->fs_info->trans_lock);
1500
1501         /*
1502          * If the transaction is removed from the list, it means this
1503          * transaction has been committed successfully, so it is impossible
1504          * to call the cleanup function.
1505          */
1506         BUG_ON(list_empty(&cur_trans->list));
1507
1508         list_del_init(&cur_trans->list);
1509         if (cur_trans == root->fs_info->running_transaction) {
1510                 cur_trans->state = TRANS_STATE_COMMIT_DOING;
1511                 spin_unlock(&root->fs_info->trans_lock);
1512                 wait_event(cur_trans->writer_wait,
1513                            atomic_read(&cur_trans->num_writers) == 1);
1514
1515                 spin_lock(&root->fs_info->trans_lock);
1516         }
1517         spin_unlock(&root->fs_info->trans_lock);
1518
1519         btrfs_cleanup_one_transaction(trans->transaction, root);
1520
1521         spin_lock(&root->fs_info->trans_lock);
1522         if (cur_trans == root->fs_info->running_transaction)
1523                 root->fs_info->running_transaction = NULL;
1524         spin_unlock(&root->fs_info->trans_lock);
1525
1526         put_transaction(cur_trans);
1527         put_transaction(cur_trans);
1528
1529         trace_btrfs_transaction_commit(root);
1530
1531         btrfs_scrub_continue(root);
1532
1533         if (current->journal_info == trans)
1534                 current->journal_info = NULL;
1535
1536         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1537 }
1538
1539 static int btrfs_flush_all_pending_stuffs(struct btrfs_trans_handle *trans,
1540                                           struct btrfs_root *root)
1541 {
1542         int ret;
1543
1544         ret = btrfs_run_delayed_items(trans, root);
1545         if (ret)
1546                 return ret;
1547
1548         /*
1549          * running the delayed items may have added new refs. account
1550          * them now so that they hinder processing of more delayed refs
1551          * as little as possible.
1552          */
1553         btrfs_delayed_refs_qgroup_accounting(trans, root->fs_info);
1554
1555         /*
1556          * rename don't use btrfs_join_transaction, so, once we
1557          * set the transaction to blocked above, we aren't going
1558          * to get any new ordered operations.  We can safely run
1559          * it here and no for sure that nothing new will be added
1560          * to the list
1561          */
1562         ret = btrfs_run_ordered_operations(trans, root, 1);
1563
1564         return ret;
1565 }
1566
1567 static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)
1568 {
1569         if (btrfs_test_opt(fs_info->tree_root, FLUSHONCOMMIT))
1570                 return btrfs_start_all_delalloc_inodes(fs_info, 1);
1571         return 0;
1572 }
1573
1574 static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
1575 {
1576         if (btrfs_test_opt(fs_info->tree_root, FLUSHONCOMMIT))
1577                 btrfs_wait_all_ordered_extents(fs_info, 1);
1578 }
1579
1580 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1581                              struct btrfs_root *root)
1582 {
1583         struct btrfs_transaction *cur_trans = trans->transaction;
1584         struct btrfs_transaction *prev_trans = NULL;
1585         int ret;
1586
1587         ret = btrfs_run_ordered_operations(trans, root, 0);
1588         if (ret) {
1589                 btrfs_abort_transaction(trans, root, ret);
1590                 btrfs_end_transaction(trans, root);
1591                 return ret;
1592         }
1593
1594         /* Stop the commit early if ->aborted is set */
1595         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1596                 ret = cur_trans->aborted;
1597                 btrfs_end_transaction(trans, root);
1598                 return ret;
1599         }
1600
1601         /* make a pass through all the delayed refs we have so far
1602          * any runnings procs may add more while we are here
1603          */
1604         ret = btrfs_run_delayed_refs(trans, root, 0);
1605         if (ret) {
1606                 btrfs_end_transaction(trans, root);
1607                 return ret;
1608         }
1609
1610         btrfs_trans_release_metadata(trans, root);
1611         trans->block_rsv = NULL;
1612         if (trans->qgroup_reserved) {
1613                 btrfs_qgroup_free(root, trans->qgroup_reserved);
1614                 trans->qgroup_reserved = 0;
1615         }
1616
1617         cur_trans = trans->transaction;
1618
1619         /*
1620          * set the flushing flag so procs in this transaction have to
1621          * start sending their work down.
1622          */
1623         cur_trans->delayed_refs.flushing = 1;
1624         smp_wmb();
1625
1626         if (!list_empty(&trans->new_bgs))
1627                 btrfs_create_pending_block_groups(trans, root);
1628
1629         ret = btrfs_run_delayed_refs(trans, root, 0);
1630         if (ret) {
1631                 btrfs_end_transaction(trans, root);
1632                 return ret;
1633         }
1634
1635         spin_lock(&root->fs_info->trans_lock);
1636         if (cur_trans->state >= TRANS_STATE_COMMIT_START) {
1637                 spin_unlock(&root->fs_info->trans_lock);
1638                 atomic_inc(&cur_trans->use_count);
1639                 ret = btrfs_end_transaction(trans, root);
1640
1641                 wait_for_commit(root, cur_trans);
1642
1643                 put_transaction(cur_trans);
1644
1645                 return ret;
1646         }
1647
1648         cur_trans->state = TRANS_STATE_COMMIT_START;
1649         wake_up(&root->fs_info->transaction_blocked_wait);
1650
1651         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1652                 prev_trans = list_entry(cur_trans->list.prev,
1653                                         struct btrfs_transaction, list);
1654                 if (prev_trans->state != TRANS_STATE_COMPLETED) {
1655                         atomic_inc(&prev_trans->use_count);
1656                         spin_unlock(&root->fs_info->trans_lock);
1657
1658                         wait_for_commit(root, prev_trans);
1659
1660                         put_transaction(prev_trans);
1661                 } else {
1662                         spin_unlock(&root->fs_info->trans_lock);
1663                 }
1664         } else {
1665                 spin_unlock(&root->fs_info->trans_lock);
1666         }
1667
1668         extwriter_counter_dec(cur_trans, trans->type);
1669
1670         ret = btrfs_start_delalloc_flush(root->fs_info);
1671         if (ret)
1672                 goto cleanup_transaction;
1673
1674         ret = btrfs_flush_all_pending_stuffs(trans, root);
1675         if (ret)
1676                 goto cleanup_transaction;
1677
1678         wait_event(cur_trans->writer_wait,
1679                    extwriter_counter_read(cur_trans) == 0);
1680
1681         /* some pending stuffs might be added after the previous flush. */
1682         ret = btrfs_flush_all_pending_stuffs(trans, root);
1683         if (ret)
1684                 goto cleanup_transaction;
1685
1686         btrfs_wait_delalloc_flush(root->fs_info);
1687         /*
1688          * Ok now we need to make sure to block out any other joins while we
1689          * commit the transaction.  We could have started a join before setting
1690          * COMMIT_DOING so make sure to wait for num_writers to == 1 again.
1691          */
1692         spin_lock(&root->fs_info->trans_lock);
1693         cur_trans->state = TRANS_STATE_COMMIT_DOING;
1694         spin_unlock(&root->fs_info->trans_lock);
1695         wait_event(cur_trans->writer_wait,
1696                    atomic_read(&cur_trans->num_writers) == 1);
1697
1698         /* ->aborted might be set after the previous check, so check it */
1699         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1700                 ret = cur_trans->aborted;
1701                 goto cleanup_transaction;
1702         }
1703         /*
1704          * the reloc mutex makes sure that we stop
1705          * the balancing code from coming in and moving
1706          * extents around in the middle of the commit
1707          */
1708         mutex_lock(&root->fs_info->reloc_mutex);
1709
1710         /*
1711          * We needn't worry about the delayed items because we will
1712          * deal with them in create_pending_snapshot(), which is the
1713          * core function of the snapshot creation.
1714          */
1715         ret = create_pending_snapshots(trans, root->fs_info);
1716         if (ret) {
1717                 mutex_unlock(&root->fs_info->reloc_mutex);
1718                 goto cleanup_transaction;
1719         }
1720
1721         /*
1722          * We insert the dir indexes of the snapshots and update the inode
1723          * of the snapshots' parents after the snapshot creation, so there
1724          * are some delayed items which are not dealt with. Now deal with
1725          * them.
1726          *
1727          * We needn't worry that this operation will corrupt the snapshots,
1728          * because all the tree which are snapshoted will be forced to COW
1729          * the nodes and leaves.
1730          */
1731         ret = btrfs_run_delayed_items(trans, root);
1732         if (ret) {
1733                 mutex_unlock(&root->fs_info->reloc_mutex);
1734                 goto cleanup_transaction;
1735         }
1736
1737         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1738         if (ret) {
1739                 mutex_unlock(&root->fs_info->reloc_mutex);
1740                 goto cleanup_transaction;
1741         }
1742
1743         /*
1744          * make sure none of the code above managed to slip in a
1745          * delayed item
1746          */
1747         btrfs_assert_delayed_root_empty(root);
1748
1749         WARN_ON(cur_trans != trans->transaction);
1750
1751         btrfs_scrub_pause(root);
1752         /* btrfs_commit_tree_roots is responsible for getting the
1753          * various roots consistent with each other.  Every pointer
1754          * in the tree of tree roots has to point to the most up to date
1755          * root for every subvolume and other tree.  So, we have to keep
1756          * the tree logging code from jumping in and changing any
1757          * of the trees.
1758          *
1759          * At this point in the commit, there can't be any tree-log
1760          * writers, but a little lower down we drop the trans mutex
1761          * and let new people in.  By holding the tree_log_mutex
1762          * from now until after the super is written, we avoid races
1763          * with the tree-log code.
1764          */
1765         mutex_lock(&root->fs_info->tree_log_mutex);
1766
1767         ret = commit_fs_roots(trans, root);
1768         if (ret) {
1769                 mutex_unlock(&root->fs_info->tree_log_mutex);
1770                 mutex_unlock(&root->fs_info->reloc_mutex);
1771                 goto cleanup_transaction;
1772         }
1773
1774         /* commit_fs_roots gets rid of all the tree log roots, it is now
1775          * safe to free the root of tree log roots
1776          */
1777         btrfs_free_log_root_tree(trans, root->fs_info);
1778
1779         ret = commit_cowonly_roots(trans, root);
1780         if (ret) {
1781                 mutex_unlock(&root->fs_info->tree_log_mutex);
1782                 mutex_unlock(&root->fs_info->reloc_mutex);
1783                 goto cleanup_transaction;
1784         }
1785
1786         /*
1787          * The tasks which save the space cache and inode cache may also
1788          * update ->aborted, check it.
1789          */
1790         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1791                 ret = cur_trans->aborted;
1792                 mutex_unlock(&root->fs_info->tree_log_mutex);
1793                 mutex_unlock(&root->fs_info->reloc_mutex);
1794                 goto cleanup_transaction;
1795         }
1796
1797         btrfs_prepare_extent_commit(trans, root);
1798
1799         cur_trans = root->fs_info->running_transaction;
1800
1801         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1802                             root->fs_info->tree_root->node);
1803         switch_commit_root(root->fs_info->tree_root);
1804
1805         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1806                             root->fs_info->chunk_root->node);
1807         switch_commit_root(root->fs_info->chunk_root);
1808
1809         assert_qgroups_uptodate(trans);
1810         update_super_roots(root);
1811
1812         if (!root->fs_info->log_root_recovering) {
1813                 btrfs_set_super_log_root(root->fs_info->super_copy, 0);
1814                 btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
1815         }
1816
1817         memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
1818                sizeof(*root->fs_info->super_copy));
1819
1820         spin_lock(&root->fs_info->trans_lock);
1821         cur_trans->state = TRANS_STATE_UNBLOCKED;
1822         root->fs_info->running_transaction = NULL;
1823         spin_unlock(&root->fs_info->trans_lock);
1824         mutex_unlock(&root->fs_info->reloc_mutex);
1825
1826         wake_up(&root->fs_info->transaction_wait);
1827
1828         ret = btrfs_write_and_wait_transaction(trans, root);
1829         if (ret) {
1830                 btrfs_error(root->fs_info, ret,
1831                             "Error while writing out transaction");
1832                 mutex_unlock(&root->fs_info->tree_log_mutex);
1833                 goto cleanup_transaction;
1834         }
1835
1836         ret = write_ctree_super(trans, root, 0);
1837         if (ret) {
1838                 mutex_unlock(&root->fs_info->tree_log_mutex);
1839                 goto cleanup_transaction;
1840         }
1841
1842         /*
1843          * the super is written, we can safely allow the tree-loggers
1844          * to go about their business
1845          */
1846         mutex_unlock(&root->fs_info->tree_log_mutex);
1847
1848         btrfs_finish_extent_commit(trans, root);
1849
1850         root->fs_info->last_trans_committed = cur_trans->transid;
1851         /*
1852          * We needn't acquire the lock here because there is no other task
1853          * which can change it.
1854          */
1855         cur_trans->state = TRANS_STATE_COMPLETED;
1856         wake_up(&cur_trans->commit_wait);
1857
1858         spin_lock(&root->fs_info->trans_lock);
1859         list_del_init(&cur_trans->list);
1860         spin_unlock(&root->fs_info->trans_lock);
1861
1862         put_transaction(cur_trans);
1863         put_transaction(cur_trans);
1864
1865         if (trans->type & __TRANS_FREEZABLE)
1866                 sb_end_intwrite(root->fs_info->sb);
1867
1868         trace_btrfs_transaction_commit(root);
1869
1870         btrfs_scrub_continue(root);
1871
1872         if (current->journal_info == trans)
1873                 current->journal_info = NULL;
1874
1875         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1876
1877         if (current != root->fs_info->transaction_kthread)
1878                 btrfs_run_delayed_iputs(root);
1879
1880         return ret;
1881
1882 cleanup_transaction:
1883         btrfs_trans_release_metadata(trans, root);
1884         trans->block_rsv = NULL;
1885         if (trans->qgroup_reserved) {
1886                 btrfs_qgroup_free(root, trans->qgroup_reserved);
1887                 trans->qgroup_reserved = 0;
1888         }
1889         btrfs_warn(root->fs_info, "Skipping commit of aborted transaction.");
1890         if (current->journal_info == trans)
1891                 current->journal_info = NULL;
1892         cleanup_transaction(trans, root, ret);
1893
1894         return ret;
1895 }
1896
1897 /*
1898  * return < 0 if error
1899  * 0 if there are no more dead_roots at the time of call
1900  * 1 there are more to be processed, call me again
1901  *
1902  * The return value indicates there are certainly more snapshots to delete, but
1903  * if there comes a new one during processing, it may return 0. We don't mind,
1904  * because btrfs_commit_super will poke cleaner thread and it will process it a
1905  * few seconds later.
1906  */
1907 int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root)
1908 {
1909         int ret;
1910         struct btrfs_fs_info *fs_info = root->fs_info;
1911
1912         spin_lock(&fs_info->trans_lock);
1913         if (list_empty(&fs_info->dead_roots)) {
1914                 spin_unlock(&fs_info->trans_lock);
1915                 return 0;
1916         }
1917         root = list_first_entry(&fs_info->dead_roots,
1918                         struct btrfs_root, root_list);
1919         list_del(&root->root_list);
1920         spin_unlock(&fs_info->trans_lock);
1921
1922         pr_debug("btrfs: cleaner removing %llu\n",
1923                         (unsigned long long)root->objectid);
1924
1925         btrfs_kill_all_delayed_nodes(root);
1926
1927         if (btrfs_header_backref_rev(root->node) <
1928                         BTRFS_MIXED_BACKREF_REV)
1929                 ret = btrfs_drop_snapshot(root, NULL, 0, 0);
1930         else
1931                 ret = btrfs_drop_snapshot(root, NULL, 1, 0);
1932         /*
1933          * If we encounter a transaction abort during snapshot cleaning, we
1934          * don't want to crash here
1935          */
1936         BUG_ON(ret < 0 && ret != -EAGAIN && ret != -EROFS);
1937         return 1;
1938 }