fs/btrfs/transaction.c

   1 // SPDX-License-Identifier: GPL-2.0
   2 /*
   3  * Copyright (C) 2007 Oracle.  All rights reserved.
   4  */
   5
   6 #include <linux/fs.h>
   7 #include <linux/slab.h>
   8 #include <linux/sched.h>
   9 #include <linux/writeback.h>
  10 #include <linux/pagemap.h>
  11 #include <linux/blkdev.h>
  12 #include <linux/uuid.h>
  13 #include "misc.h"
  14 #include "ctree.h"
  15 #include "disk-io.h"
  16 #include "transaction.h"
  17 #include "locking.h"
  18 #include "tree-log.h"
  19 #include "inode-map.h"
  20 #include "volumes.h"
  21 #include "dev-replace.h"
  22 #include "qgroup.h"
  23 #include "block-group.h"
  24 #include "space-info.h"
  25
  26 #define BTRFS_ROOT_TRANS_TAG 0
  27
  28 /*
  29  * Transaction states and transitions
  30  *
  31  * No running transaction (fs tree blocks are not modified)
  32  * |
  33  * | To next stage:
  34  * |  Call start_transaction() variants. Except btrfs_join_transaction_nostart().
  35  * V
  36  * Transaction N [[TRANS_STATE_RUNNING]]
  37  * |
  38  * | New trans handles can be attached to transaction N by calling all
  39  * | start_transaction() variants.
  40  * |
  41  * | To next stage:
  42  * |  Call btrfs_commit_transaction() on any trans handle attached to
  43  * |  transaction N
  44  * V
  45  * Transaction N [[TRANS_STATE_COMMIT_START]]
  46  * |
  47  * | Will wait for previous running transaction to completely finish if there
  48  * | is one
  49  * |
  50  * | Then one of the following happes:
  51  * | - Wait for all other trans handle holders to release.
  52  * |   The btrfs_commit_transaction() caller will do the commit work.
  53  * | - Wait for current transaction to be committed by others.
  54  * |   Other btrfs_commit_transaction() caller will do the commit work.
  55  * |
  56  * | At this stage, only btrfs_join_transaction*() variants can attach
  57  * | to this running transaction.
  58  * | All other variants will wait for current one to finish and attach to
  59  * | transaction N+1.
  60  * |
  61  * | To next stage:
  62  * |  Caller is chosen to commit transaction N, and all other trans handle
  63  * |  haven been released.
  64  * V
  65  * Transaction N [[TRANS_STATE_COMMIT_DOING]]
  66  * |
  67  * | The heavy lifting transaction work is started.
  68  * | From running delayed refs (modifying extent tree) to creating pending
  69  * | snapshots, running qgroups.
  70  * | In short, modify supporting trees to reflect modifications of subvolume
  71  * | trees.
  72  * |
  73  * | At this stage, all start_transaction() calls will wait for this
  74  * | transaction to finish and attach to transaction N+1.
  75  * |
  76  * | To next stage:
  77  * |  Until all supporting trees are updated.
  78  * V
  79  * Transaction N [[TRANS_STATE_UNBLOCKED]]
  80  * |                                                Transaction N+1
  81  * | All needed trees are modified, thus we only    [[TRANS_STATE_RUNNING]]
  82  * | need to write them back to disk and update     |
  83  * | super blocks.                                  |
  84  * |                                                |
  85  * | At this stage, new transaction is allowed to   |
  86  * | start.                                         |
  87  * | All new start_transaction() calls will be      |
  88  * | attached to transid N+1.                       |
  89  * |                                                |
  90  * | To next stage:                                 |
  91  * |  Until all tree blocks are super blocks are    |
  92  * |  written to block devices                      |
  93  * V                                                |
  94  * Transaction N [[TRANS_STATE_COMPLETED]]          V
  95  *   All tree blocks and super blocks are written.  Transaction N+1
  96  *   This transaction is finished and all its       [[TRANS_STATE_COMMIT_START]]
  97  *   data structures will be cleaned up.            | Life goes on
  98  */
  99 static const unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {
 100         [TRANS_STATE_RUNNING]           = 0U,
 101         [TRANS_STATE_COMMIT_START]      = (__TRANS_START | __TRANS_ATTACH),
 102         [TRANS_STATE_COMMIT_DOING]      = (__TRANS_START |
 103                                            __TRANS_ATTACH |
 104                                            __TRANS_JOIN |
 105                                            __TRANS_JOIN_NOSTART),
 106         [TRANS_STATE_UNBLOCKED]         = (__TRANS_START |
 107                                            __TRANS_ATTACH |
 108                                            __TRANS_JOIN |
 109                                            __TRANS_JOIN_NOLOCK |
 110                                            __TRANS_JOIN_NOSTART),
 111         [TRANS_STATE_COMPLETED]         = (__TRANS_START |
 112                                            __TRANS_ATTACH |
 113                                            __TRANS_JOIN |
 114                                            __TRANS_JOIN_NOLOCK |
 115                                            __TRANS_JOIN_NOSTART),
 116 };
 117
 118 void btrfs_put_transaction(struct btrfs_transaction *transaction)
 119 {
 120         WARN_ON(refcount_read(&transaction->use_count) == 0);
 121         if (refcount_dec_and_test(&transaction->use_count)) {
 122                 BUG_ON(!list_empty(&transaction->list));
 123                 WARN_ON(!RB_EMPTY_ROOT(
 124                                 &transaction->delayed_refs.href_root.rb_root));
 125                 WARN_ON(!RB_EMPTY_ROOT(
 126                                 &transaction->delayed_refs.dirty_extent_root));
 127                 if (transaction->delayed_refs.pending_csums)
 128                         btrfs_err(transaction->fs_info,
 129                                   "pending csums is %llu",
 130                                   transaction->delayed_refs.pending_csums);
 131                 /*
 132                  * If any block groups are found in ->deleted_bgs then it's
 133                  * because the transaction was aborted and a commit did not
 134                  * happen (things failed before writing the new superblock
 135                  * and calling btrfs_finish_extent_commit()), so we can not
 136                  * discard the physical locations of the block groups.
 137                  */
 138                 while (!list_empty(&transaction->deleted_bgs)) {
 139                         struct btrfs_block_group *cache;
 140
 141                         cache = list_first_entry(&transaction->deleted_bgs,
 142                                                  struct btrfs_block_group,
 143                                                  bg_list);
 144                         list_del_init(&cache->bg_list);
 145                         btrfs_unfreeze_block_group(cache);
 146                         btrfs_put_block_group(cache);
 147                 }
 148                 WARN_ON(!list_empty(&transaction->dev_update_list));
 149                 kfree(transaction);
 150         }
 151 }
 152
 153 static noinline void switch_commit_roots(struct btrfs_trans_handle *trans)
 154 {
 155         struct btrfs_transaction *cur_trans = trans->transaction;
 156         struct btrfs_fs_info *fs_info = trans->fs_info;
 157         struct btrfs_root *root, *tmp;
 158         struct btrfs_caching_control *caching_ctl, *next;
 159
 160         down_write(&fs_info->commit_root_sem);
 161         list_for_each_entry_safe(root, tmp, &cur_trans->switch_commits,
 162                                  dirty_list) {
 163                 list_del_init(&root->dirty_list);
 164                 free_extent_buffer(root->commit_root);
 165                 root->commit_root = btrfs_root_node(root);
 166                 if (is_fstree(root->root_key.objectid))
 167                         btrfs_unpin_free_ino(root);
 168                 extent_io_tree_release(&root->dirty_log_pages);
 169                 btrfs_qgroup_clean_swapped_blocks(root);
 170         }
 171
 172         /* We can free old roots now. */
 173         spin_lock(&cur_trans->dropped_roots_lock);
 174         while (!list_empty(&cur_trans->dropped_roots)) {
 175                 root = list_first_entry(&cur_trans->dropped_roots,
 176                                         struct btrfs_root, root_list);
 177                 list_del_init(&root->root_list);
 178                 spin_unlock(&cur_trans->dropped_roots_lock);
 179                 btrfs_free_log(trans, root);
 180                 btrfs_drop_and_free_fs_root(fs_info, root);
 181                 spin_lock(&cur_trans->dropped_roots_lock);
 182         }
 183         spin_unlock(&cur_trans->dropped_roots_lock);
 184
 185         /*
 186          * We have to update the last_byte_to_unpin under the commit_root_sem,
 187          * at the same time we swap out the commit roots.
 188          *
 189          * This is because we must have a real view of the last spot the caching
 190          * kthreads were while caching.  Consider the following views of the
 191          * extent tree for a block group
 192          *
 193          * commit root
 194          * +----+----+----+----+----+----+----+
 195          * |\\\\|    |\\\\|\\\\|    |\\\\|\\\\|
 196          * +----+----+----+----+----+----+----+
 197          * 0    1    2    3    4    5    6    7
 198          *
 199          * new commit root
 200          * +----+----+----+----+----+----+----+
 201          * |    |    |    |\\\\|    |    |\\\\|
 202          * +----+----+----+----+----+----+----+
 203          * 0    1    2    3    4    5    6    7
 204          *
 205          * If the cache_ctl->progress was at 3, then we are only allowed to
 206          * unpin [0,1) and [2,3], because the caching thread has already
 207          * processed those extents.  We are not allowed to unpin [5,6), because
 208          * the caching thread will re-start it's search from 3, and thus find
 209          * the hole from [4,6) to add to the free space cache.
 210          */
 211         list_for_each_entry_safe(caching_ctl, next,
 212                                  &fs_info->caching_block_groups, list) {
 213                 struct btrfs_block_group *cache = caching_ctl->block_group;
 214
 215                 if (btrfs_block_group_done(cache)) {
 216                         cache->last_byte_to_unpin = (u64)-1;
 217                         list_del_init(&caching_ctl->list);
 218                         btrfs_put_caching_control(caching_ctl);
 219                 } else {
 220                         cache->last_byte_to_unpin = caching_ctl->progress;
 221                 }
 222         }
 223         up_write(&fs_info->commit_root_sem);
 224 }
 225
 226 static inline void extwriter_counter_inc(struct btrfs_transaction *trans,
 227                                          unsigned int type)
 228 {
 229         if (type & TRANS_EXTWRITERS)
 230                 atomic_inc(&trans->num_extwriters);
 231 }
 232
 233 static inline void extwriter_counter_dec(struct btrfs_transaction *trans,
 234                                          unsigned int type)
 235 {
 236         if (type & TRANS_EXTWRITERS)
 237                 atomic_dec(&trans->num_extwriters);
 238 }
 239
 240 static inline void extwriter_counter_init(struct btrfs_transaction *trans,
 241                                           unsigned int type)
 242 {
 243         atomic_set(&trans->num_extwriters, ((type & TRANS_EXTWRITERS) ? 1 : 0));
 244 }
 245
 246 static inline int extwriter_counter_read(struct btrfs_transaction *trans)
 247 {
 248         return atomic_read(&trans->num_extwriters);
 249 }
 250
 251 /*
 252  * To be called after all the new block groups attached to the transaction
 253  * handle have been created (btrfs_create_pending_block_groups()).
 254  */
 255 void btrfs_trans_release_chunk_metadata(struct btrfs_trans_handle *trans)
 256 {
 257         struct btrfs_fs_info *fs_info = trans->fs_info;
 258
 259         if (!trans->chunk_bytes_reserved)
 260                 return;
 261
 262         WARN_ON_ONCE(!list_empty(&trans->new_bgs));
 263
 264         btrfs_block_rsv_release(fs_info, &fs_info->chunk_block_rsv,
 265                                 trans->chunk_bytes_reserved, NULL);
 266         trans->chunk_bytes_reserved = 0;
 267 }
 268
 269 /*
 270  * either allocate a new transaction or hop into the existing one
 271  */
 272 static noinline int join_transaction(struct btrfs_fs_info *fs_info,
 273                                      unsigned int type)
 274 {
 275         struct btrfs_transaction *cur_trans;
 276
 277         spin_lock(&fs_info->trans_lock);
 278 loop:
 279         /* The file system has been taken offline. No new transactions. */
 280         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 281                 spin_unlock(&fs_info->trans_lock);
 282                 return -EROFS;
 283         }
 284
 285         cur_trans = fs_info->running_transaction;
 286         if (cur_trans) {
 287                 if (TRANS_ABORTED(cur_trans)) {
 288                         spin_unlock(&fs_info->trans_lock);
 289                         return cur_trans->aborted;
 290                 }
 291                 if (btrfs_blocked_trans_types[cur_trans->state] & type) {
 292                         spin_unlock(&fs_info->trans_lock);
 293                         return -EBUSY;
 294                 }
 295                 refcount_inc(&cur_trans->use_count);
 296                 atomic_inc(&cur_trans->num_writers);
 297                 extwriter_counter_inc(cur_trans, type);
 298                 spin_unlock(&fs_info->trans_lock);
 299                 return 0;
 300         }
 301         spin_unlock(&fs_info->trans_lock);
 302
 303         /*
 304          * If we are ATTACH or TRANS_JOIN_NOSTART, we just want to catch the
 305          * current transaction, and commit it. If there is no transaction, just
 306          * return ENOENT.
 307          */
 308         if (type == TRANS_ATTACH || type == TRANS_JOIN_NOSTART)
 309                 return -ENOENT;
 310
 311         /*
 312          * JOIN_NOLOCK only happens during the transaction commit, so
 313          * it is impossible that ->running_transaction is NULL
 314          */
 315         BUG_ON(type == TRANS_JOIN_NOLOCK);
 316
 317         cur_trans = kmalloc(sizeof(*cur_trans), GFP_NOFS);
 318         if (!cur_trans)
 319                 return -ENOMEM;
 320
 321         spin_lock(&fs_info->trans_lock);
 322         if (fs_info->running_transaction) {
 323                 /*
 324                  * someone started a transaction after we unlocked.  Make sure
 325                  * to redo the checks above
 326                  */
 327                 kfree(cur_trans);
 328                 goto loop;
 329         } else if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 330                 spin_unlock(&fs_info->trans_lock);
 331                 kfree(cur_trans);
 332                 return -EROFS;
 333         }
 334
 335         cur_trans->fs_info = fs_info;
 336         atomic_set(&cur_trans->pending_ordered, 0);
 337         init_waitqueue_head(&cur_trans->pending_wait);
 338         atomic_set(&cur_trans->num_writers, 1);
 339         extwriter_counter_init(cur_trans, type);
 340         init_waitqueue_head(&cur_trans->writer_wait);
 341         init_waitqueue_head(&cur_trans->commit_wait);
 342         cur_trans->state = TRANS_STATE_RUNNING;
 343         /*
 344          * One for this trans handle, one so it will live on until we
 345          * commit the transaction.
 346          */
 347         refcount_set(&cur_trans->use_count, 2);
 348         cur_trans->flags = 0;
 349         cur_trans->start_time = ktime_get_seconds();
 350
 351         memset(&cur_trans->delayed_refs, 0, sizeof(cur_trans->delayed_refs));
 352
 353         cur_trans->delayed_refs.href_root = RB_ROOT_CACHED;
 354         cur_trans->delayed_refs.dirty_extent_root = RB_ROOT;
 355         atomic_set(&cur_trans->delayed_refs.num_entries, 0);
 356
 357         /*
 358          * although the tree mod log is per file system and not per transaction,
 359          * the log must never go across transaction boundaries.
 360          */
 361         smp_mb();
 362         if (!list_empty(&fs_info->tree_mod_seq_list))
 363                 WARN(1, KERN_ERR "BTRFS: tree_mod_seq_list not empty when creating a fresh transaction\n");
 364         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log))
 365                 WARN(1, KERN_ERR "BTRFS: tree_mod_log rb tree not empty when creating a fresh transaction\n");
 366         atomic64_set(&fs_info->tree_mod_seq, 0);
 367
 368         spin_lock_init(&cur_trans->delayed_refs.lock);
 369
 370         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 371         INIT_LIST_HEAD(&cur_trans->dev_update_list);
 372         INIT_LIST_HEAD(&cur_trans->switch_commits);
 373         INIT_LIST_HEAD(&cur_trans->dirty_bgs);
 374         INIT_LIST_HEAD(&cur_trans->io_bgs);
 375         INIT_LIST_HEAD(&cur_trans->dropped_roots);
 376         mutex_init(&cur_trans->cache_write_mutex);
 377         spin_lock_init(&cur_trans->dirty_bgs_lock);
 378         INIT_LIST_HEAD(&cur_trans->deleted_bgs);
 379         spin_lock_init(&cur_trans->dropped_roots_lock);
 380         list_add_tail(&cur_trans->list, &fs_info->trans_list);
 381         extent_io_tree_init(fs_info, &cur_trans->dirty_pages,
 382                         IO_TREE_TRANS_DIRTY_PAGES, fs_info->btree_inode);
 383         extent_io_tree_init(fs_info, &cur_trans->pinned_extents,
 384                         IO_TREE_FS_PINNED_EXTENTS, NULL);
 385         fs_info->generation++;
 386         cur_trans->transid = fs_info->generation;
 387         fs_info->running_transaction = cur_trans;
 388         cur_trans->aborted = 0;
 389         spin_unlock(&fs_info->trans_lock);
 390
 391         return 0;
 392 }
 393
 394 /*
 395  * This does all the record keeping required to make sure that a shareable root
 396  * is properly recorded in a given transaction.  This is required to make sure
 397  * the old root from before we joined the transaction is deleted when the
 398  * transaction commits.
 399  */
 400 static int record_root_in_trans(struct btrfs_trans_handle *trans,
 401                                struct btrfs_root *root,
 402                                int force)
 403 {
 404         struct btrfs_fs_info *fs_info = root->fs_info;
 405
 406         if ((test_bit(BTRFS_ROOT_SHAREABLE, &root->state) &&
 407             root->last_trans < trans->transid) || force) {
 408                 WARN_ON(root == fs_info->extent_root);
 409                 WARN_ON(!force && root->commit_root != root->node);
 410
 411                 /*
 412                  * see below for IN_TRANS_SETUP usage rules
 413                  * we have the reloc mutex held now, so there
 414                  * is only one writer in this function
 415                  */
 416                 set_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
 417
 418                 /* make sure readers find IN_TRANS_SETUP before
 419                  * they find our root->last_trans update
 420                  */
 421                 smp_wmb();
 422
 423                 spin_lock(&fs_info->fs_roots_radix_lock);
 424                 if (root->last_trans == trans->transid && !force) {
 425                         spin_unlock(&fs_info->fs_roots_radix_lock);
 426                         return 0;
 427                 }
 428                 radix_tree_tag_set(&fs_info->fs_roots_radix,
 429                                    (unsigned long)root->root_key.objectid,
 430                                    BTRFS_ROOT_TRANS_TAG);
 431                 spin_unlock(&fs_info->fs_roots_radix_lock);
 432                 root->last_trans = trans->transid;
 433
 434                 /* this is pretty tricky.  We don't want to
 435                  * take the relocation lock in btrfs_record_root_in_trans
 436                  * unless we're really doing the first setup for this root in
 437                  * this transaction.
 438                  *
 439                  * Normally we'd use root->last_trans as a flag to decide
 440                  * if we want to take the expensive mutex.
 441                  *
 442                  * But, we have to set root->last_trans before we
 443                  * init the relocation root, otherwise, we trip over warnings
 444                  * in ctree.c.  The solution used here is to flag ourselves
 445                  * with root IN_TRANS_SETUP.  When this is 1, we're still
 446                  * fixing up the reloc trees and everyone must wait.
 447                  *
 448                  * When this is zero, they can trust root->last_trans and fly
 449                  * through btrfs_record_root_in_trans without having to take the
 450                  * lock.  smp_wmb() makes sure that all the writes above are
 451                  * done before we pop in the zero below
 452                  */
 453                 btrfs_init_reloc_root(trans, root);
 454                 smp_mb__before_atomic();
 455                 clear_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
 456         }
 457         return 0;
 458 }
 459
 460
 461 void btrfs_add_dropped_root(struct btrfs_trans_handle *trans,
 462                             struct btrfs_root *root)
 463 {
 464         struct btrfs_fs_info *fs_info = root->fs_info;
 465         struct btrfs_transaction *cur_trans = trans->transaction;
 466
 467         /* Add ourselves to the transaction dropped list */
 468         spin_lock(&cur_trans->dropped_roots_lock);
 469         list_add_tail(&root->root_list, &cur_trans->dropped_roots);
 470         spin_unlock(&cur_trans->dropped_roots_lock);
 471
 472         /* Make sure we don't try to update the root at commit time */
 473         spin_lock(&fs_info->fs_roots_radix_lock);
 474         radix_tree_tag_clear(&fs_info->fs_roots_radix,
 475                              (unsigned long)root->root_key.objectid,
 476                              BTRFS_ROOT_TRANS_TAG);
 477         spin_unlock(&fs_info->fs_roots_radix_lock);
 478 }
 479
 480 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 481                                struct btrfs_root *root)
 482 {
 483         struct btrfs_fs_info *fs_info = root->fs_info;
 484
 485         if (!test_bit(BTRFS_ROOT_SHAREABLE, &root->state))
 486                 return 0;
 487
 488         /*
 489          * see record_root_in_trans for comments about IN_TRANS_SETUP usage
 490          * and barriers
 491          */
 492         smp_rmb();
 493         if (root->last_trans == trans->transid &&
 494             !test_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state))
 495                 return 0;
 496
 497         mutex_lock(&fs_info->reloc_mutex);
 498         record_root_in_trans(trans, root, 0);
 499         mutex_unlock(&fs_info->reloc_mutex);
 500
 501         return 0;
 502 }
 503
 504 static inline int is_transaction_blocked(struct btrfs_transaction *trans)
 505 {
 506         return (trans->state >= TRANS_STATE_COMMIT_START &&
 507                 trans->state < TRANS_STATE_UNBLOCKED &&
 508                 !TRANS_ABORTED(trans));
 509 }
 510
 511 /* wait for commit against the current transaction to become unblocked
 512  * when this is done, it is safe to start a new transaction, but the current
 513  * transaction might not be fully on disk.
 514  */
 515 static void wait_current_trans(struct btrfs_fs_info *fs_info)
 516 {
 517         struct btrfs_transaction *cur_trans;
 518
 519         spin_lock(&fs_info->trans_lock);
 520         cur_trans = fs_info->running_transaction;
 521         if (cur_trans && is_transaction_blocked(cur_trans)) {
 522                 refcount_inc(&cur_trans->use_count);
 523                 spin_unlock(&fs_info->trans_lock);
 524
 525                 wait_event(fs_info->transaction_wait,
 526                            cur_trans->state >= TRANS_STATE_UNBLOCKED ||
 527                            TRANS_ABORTED(cur_trans));
 528                 btrfs_put_transaction(cur_trans);
 529         } else {
 530                 spin_unlock(&fs_info->trans_lock);
 531         }
 532 }
 533
 534 static int may_wait_transaction(struct btrfs_fs_info *fs_info, int type)
 535 {
 536         if (test_bit(BTRFS_FS_LOG_RECOVERING, &fs_info->flags))
 537                 return 0;
 538
 539         if (type == TRANS_START)
 540                 return 1;
 541
 542         return 0;
 543 }
 544
 545 static inline bool need_reserve_reloc_root(struct btrfs_root *root)
 546 {
 547         struct btrfs_fs_info *fs_info = root->fs_info;
 548
 549         if (!fs_info->reloc_ctl ||
 550             !test_bit(BTRFS_ROOT_SHAREABLE, &root->state) ||
 551             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 552             root->reloc_root)
 553                 return false;
 554
 555         return true;
 556 }
 557
 558 static struct btrfs_trans_handle *
 559 start_transaction(struct btrfs_root *root, unsigned int num_items,
 560                   unsigned int type, enum btrfs_reserve_flush_enum flush,
 561                   bool enforce_qgroups)
 562 {
 563         struct btrfs_fs_info *fs_info = root->fs_info;
 564         struct btrfs_block_rsv *delayed_refs_rsv = &fs_info->delayed_refs_rsv;
 565         struct btrfs_trans_handle *h;
 566         struct btrfs_transaction *cur_trans;
 567         u64 num_bytes = 0;
 568         u64 qgroup_reserved = 0;
 569         bool reloc_reserved = false;
 570         bool do_chunk_alloc = false;
 571         int ret;
 572
 573         /* Send isn't supposed to start transactions. */
 574         ASSERT(current->journal_info != BTRFS_SEND_TRANS_STUB);
 575
 576         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state))
 577                 return ERR_PTR(-EROFS);
 578
 579         if (current->journal_info) {
 580                 WARN_ON(type & TRANS_EXTWRITERS);
 581                 h = current->journal_info;
 582                 refcount_inc(&h->use_count);
 583                 WARN_ON(refcount_read(&h->use_count) > 2);
 584                 h->orig_rsv = h->block_rsv;
 585                 h->block_rsv = NULL;
 586                 goto got_it;
 587         }
 588
 589         /*
 590          * Do the reservation before we join the transaction so we can do all
 591          * the appropriate flushing if need be.
 592          */
 593         if (num_items && root != fs_info->chunk_root) {
 594                 struct btrfs_block_rsv *rsv = &fs_info->trans_block_rsv;
 595                 u64 delayed_refs_bytes = 0;
 596
 597                 qgroup_reserved = num_items * fs_info->nodesize;
 598                 ret = btrfs_qgroup_reserve_meta_pertrans(root, qgroup_reserved,
 599                                 enforce_qgroups);
 600                 if (ret)
 601                         return ERR_PTR(ret);
 602
 603                 /*
 604                  * We want to reserve all the bytes we may need all at once, so
 605                  * we only do 1 enospc flushing cycle per transaction start.  We
 606                  * accomplish this by simply assuming we'll do 2 x num_items
 607                  * worth of delayed refs updates in this trans handle, and
 608                  * refill that amount for whatever is missing in the reserve.
 609                  */
 610                 num_bytes = btrfs_calc_insert_metadata_size(fs_info, num_items);
 611                 if (flush == BTRFS_RESERVE_FLUSH_ALL &&
 612                     delayed_refs_rsv->full == 0) {
 613                         delayed_refs_bytes = num_bytes;
 614                         num_bytes <<= 1;
 615                 }
 616
 617                 /*
 618                  * Do the reservation for the relocation root creation
 619                  */
 620                 if (need_reserve_reloc_root(root)) {
 621                         num_bytes += fs_info->nodesize;
 622                         reloc_reserved = true;
 623                 }
 624
 625                 ret = btrfs_block_rsv_add(root, rsv, num_bytes, flush);
 626                 if (ret)
 627                         goto reserve_fail;
 628                 if (delayed_refs_bytes) {
 629                         btrfs_migrate_to_delayed_refs_rsv(fs_info, rsv,
 630                                                           delayed_refs_bytes);
 631                         num_bytes -= delayed_refs_bytes;
 632                 }
 633
 634                 if (rsv->space_info->force_alloc)
 635                         do_chunk_alloc = true;
 636         } else if (num_items == 0 && flush == BTRFS_RESERVE_FLUSH_ALL &&
 637                    !delayed_refs_rsv->full) {
 638                 /*
 639                  * Some people call with btrfs_start_transaction(root, 0)
 640                  * because they can be throttled, but have some other mechanism
 641                  * for reserving space.  We still want these guys to refill the
 642                  * delayed block_rsv so just add 1 items worth of reservation
 643                  * here.
 644                  */
 645                 ret = btrfs_delayed_refs_rsv_refill(fs_info, flush);
 646                 if (ret)
 647                         goto reserve_fail;
 648         }
 649 again:
 650         h = kmem_cache_zalloc(btrfs_trans_handle_cachep, GFP_NOFS);
 651         if (!h) {
 652                 ret = -ENOMEM;
 653                 goto alloc_fail;
 654         }
 655
 656         /*
 657          * If we are JOIN_NOLOCK we're already committing a transaction and
 658          * waiting on this guy, so we don't need to do the sb_start_intwrite
 659          * because we're already holding a ref.  We need this because we could
 660          * have raced in and did an fsync() on a file which can kick a commit
 661          * and then we deadlock with somebody doing a freeze.
 662          *
 663          * If we are ATTACH, it means we just want to catch the current
 664          * transaction and commit it, so we needn't do sb_start_intwrite().
 665          */
 666         if (type & __TRANS_FREEZABLE)
 667                 sb_start_intwrite(fs_info->sb);
 668
 669         if (may_wait_transaction(fs_info, type))
 670                 wait_current_trans(fs_info);
 671
 672         do {
 673                 ret = join_transaction(fs_info, type);
 674                 if (ret == -EBUSY) {
 675                         wait_current_trans(fs_info);
 676                         if (unlikely(type == TRANS_ATTACH ||
 677                                      type == TRANS_JOIN_NOSTART))
 678                                 ret = -ENOENT;
 679                 }
 680         } while (ret == -EBUSY);
 681
 682         if (ret < 0)
 683                 goto join_fail;
 684
 685         cur_trans = fs_info->running_transaction;
 686
 687         h->transid = cur_trans->transid;
 688         h->transaction = cur_trans;
 689         h->root = root;
 690         refcount_set(&h->use_count, 1);
 691         h->fs_info = root->fs_info;
 692
 693         h->type = type;
 694         h->can_flush_pending_bgs = true;
 695         INIT_LIST_HEAD(&h->new_bgs);
 696
 697         smp_mb();
 698         if (cur_trans->state >= TRANS_STATE_COMMIT_START &&
 699             may_wait_transaction(fs_info, type)) {
 700                 current->journal_info = h;
 701                 btrfs_commit_transaction(h);
 702                 goto again;
 703         }
 704
 705         if (num_bytes) {
 706                 trace_btrfs_space_reservation(fs_info, "transaction",
 707                                               h->transid, num_bytes, 1);
 708                 h->block_rsv = &fs_info->trans_block_rsv;
 709                 h->bytes_reserved = num_bytes;
 710                 h->reloc_reserved = reloc_reserved;
 711         }
 712
 713 got_it:
 714         if (!current->journal_info)
 715                 current->journal_info = h;
 716
 717         /*
 718          * If the space_info is marked ALLOC_FORCE then we'll get upgraded to
 719          * ALLOC_FORCE the first run through, and then we won't allocate for
 720          * anybody else who races in later.  We don't care about the return
 721          * value here.
 722          */
 723         if (do_chunk_alloc && num_bytes) {
 724                 u64 flags = h->block_rsv->space_info->flags;
 725
 726                 btrfs_chunk_alloc(h, btrfs_get_alloc_profile(fs_info, flags),
 727                                   CHUNK_ALLOC_NO_FORCE);
 728         }
 729
 730         /*
 731          * btrfs_record_root_in_trans() needs to alloc new extents, and may
 732          * call btrfs_join_transaction() while we're also starting a
 733          * transaction.
 734          *
 735          * Thus it need to be called after current->journal_info initialized,
 736          * or we can deadlock.
 737          */
 738         btrfs_record_root_in_trans(h, root);
 739
 740         return h;
 741
 742 join_fail:
 743         if (type & __TRANS_FREEZABLE)
 744                 sb_end_intwrite(fs_info->sb);
 745         kmem_cache_free(btrfs_trans_handle_cachep, h);
 746 alloc_fail:
 747         if (num_bytes)
 748                 btrfs_block_rsv_release(fs_info, &fs_info->trans_block_rsv,
 749                                         num_bytes, NULL);
 750 reserve_fail:
 751         btrfs_qgroup_free_meta_pertrans(root, qgroup_reserved);
 752         return ERR_PTR(ret);
 753 }
 754
 755 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 756                                                    unsigned int num_items)
 757 {
 758         return start_transaction(root, num_items, TRANS_START,
 759                                  BTRFS_RESERVE_FLUSH_ALL, true);
 760 }
 761
 762 struct btrfs_trans_handle *btrfs_start_transaction_fallback_global_rsv(
 763                                         struct btrfs_root *root,
 764                                         unsigned int num_items)
 765 {
 766         return start_transaction(root, num_items, TRANS_START,
 767                                  BTRFS_RESERVE_FLUSH_ALL_STEAL, false);
 768 }
 769
 770 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 771 {
 772         return start_transaction(root, 0, TRANS_JOIN, BTRFS_RESERVE_NO_FLUSH,
 773                                  true);
 774 }
 775
 776 struct btrfs_trans_handle *btrfs_join_transaction_spacecache(struct btrfs_root *root)
 777 {
 778         return start_transaction(root, 0, TRANS_JOIN_NOLOCK,
 779                                  BTRFS_RESERVE_NO_FLUSH, true);
 780 }
 781
 782 /*
 783  * Similar to regular join but it never starts a transaction when none is
 784  * running or after waiting for the current one to finish.
 785  */
 786 struct btrfs_trans_handle *btrfs_join_transaction_nostart(struct btrfs_root *root)
 787 {
 788         return start_transaction(root, 0, TRANS_JOIN_NOSTART,
 789                                  BTRFS_RESERVE_NO_FLUSH, true);
 790 }
 791
 792 /*
 793  * btrfs_attach_transaction() - catch the running transaction
 794  *
 795  * It is used when we want to commit the current the transaction, but
 796  * don't want to start a new one.
 797  *
 798  * Note: If this function return -ENOENT, it just means there is no
 799  * running transaction. But it is possible that the inactive transaction
 800  * is still in the memory, not fully on disk. If you hope there is no
 801  * inactive transaction in the fs when -ENOENT is returned, you should
 802  * invoke
 803  *     btrfs_attach_transaction_barrier()
 804  */
 805 struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
 806 {
 807         return start_transaction(root, 0, TRANS_ATTACH,
 808                                  BTRFS_RESERVE_NO_FLUSH, true);
 809 }
 810
 811 /*
 812  * btrfs_attach_transaction_barrier() - catch the running transaction
 813  *
 814  * It is similar to the above function, the difference is this one
 815  * will wait for all the inactive transactions until they fully
 816  * complete.
 817  */
 818 struct btrfs_trans_handle *
 819 btrfs_attach_transaction_barrier(struct btrfs_root *root)
 820 {
 821         struct btrfs_trans_handle *trans;
 822
 823         trans = start_transaction(root, 0, TRANS_ATTACH,
 824                                   BTRFS_RESERVE_NO_FLUSH, true);
 825         if (trans == ERR_PTR(-ENOENT)) {
 826                 int ret;
 827
 828                 ret = btrfs_wait_for_commit(root->fs_info, 0);
 829                 if (ret)
 830                         return ERR_PTR(ret);
 831         }
 832
 833         return trans;
 834 }
 835
 836 /* wait for a transaction commit to be fully complete */
 837 static noinline void wait_for_commit(struct btrfs_transaction *commit)
 838 {
 839         wait_event(commit->commit_wait, commit->state == TRANS_STATE_COMPLETED);
 840 }
 841
 842 int btrfs_wait_for_commit(struct btrfs_fs_info *fs_info, u64 transid)
 843 {
 844         struct btrfs_transaction *cur_trans = NULL, *t;
 845         int ret = 0;
 846
 847         if (transid) {
 848                 if (transid <= fs_info->last_trans_committed)
 849                         goto out;
 850
 851                 /* find specified transaction */
 852                 spin_lock(&fs_info->trans_lock);
 853                 list_for_each_entry(t, &fs_info->trans_list, list) {
 854                         if (t->transid == transid) {
 855                                 cur_trans = t;
 856                                 refcount_inc(&cur_trans->use_count);
 857                                 ret = 0;
 858                                 break;
 859                         }
 860                         if (t->transid > transid) {
 861                                 ret = 0;
 862                                 break;
 863                         }
 864                 }
 865                 spin_unlock(&fs_info->trans_lock);
 866
 867                 /*
 868                  * The specified transaction doesn't exist, or we
 869                  * raced with btrfs_commit_transaction
 870                  */
 871                 if (!cur_trans) {
 872                         if (transid > fs_info->last_trans_committed)
 873                                 ret = -EINVAL;
 874                         goto out;
 875                 }
 876         } else {
 877                 /* find newest transaction that is committing | committed */
 878                 spin_lock(&fs_info->trans_lock);
 879                 list_for_each_entry_reverse(t, &fs_info->trans_list,
 880                                             list) {
 881                         if (t->state >= TRANS_STATE_COMMIT_START) {
 882                                 if (t->state == TRANS_STATE_COMPLETED)
 883                                         break;
 884                                 cur_trans = t;
 885                                 refcount_inc(&cur_trans->use_count);
 886                                 break;
 887                         }
 888                 }
 889                 spin_unlock(&fs_info->trans_lock);
 890                 if (!cur_trans)
 891                         goto out;  /* nothing committing|committed */
 892         }
 893
 894         wait_for_commit(cur_trans);
 895         ret = cur_trans->aborted;
 896         btrfs_put_transaction(cur_trans);
 897 out:
 898         return ret;
 899 }
 900
 901 void btrfs_throttle(struct btrfs_fs_info *fs_info)
 902 {
 903         wait_current_trans(fs_info);
 904 }
 905
 906 static int should_end_transaction(struct btrfs_trans_handle *trans)
 907 {
 908         struct btrfs_fs_info *fs_info = trans->fs_info;
 909
 910         if (btrfs_check_space_for_delayed_refs(fs_info))
 911                 return 1;
 912
 913         return !!btrfs_block_rsv_check(&fs_info->global_block_rsv, 5);
 914 }
 915
 916 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans)
 917 {
 918         struct btrfs_transaction *cur_trans = trans->transaction;
 919
 920         smp_mb();
 921         if (cur_trans->state >= TRANS_STATE_COMMIT_START ||
 922             cur_trans->delayed_refs.flushing)
 923                 return 1;
 924
 925         return should_end_transaction(trans);
 926 }
 927
 928 static void btrfs_trans_release_metadata(struct btrfs_trans_handle *trans)
 929
 930 {
 931         struct btrfs_fs_info *fs_info = trans->fs_info;
 932
 933         if (!trans->block_rsv) {
 934                 ASSERT(!trans->bytes_reserved);
 935                 return;
 936         }
 937
 938         if (!trans->bytes_reserved)
 939                 return;
 940
 941         ASSERT(trans->block_rsv == &fs_info->trans_block_rsv);
 942         trace_btrfs_space_reservation(fs_info, "transaction",
 943                                       trans->transid, trans->bytes_reserved, 0);
 944         btrfs_block_rsv_release(fs_info, trans->block_rsv,
 945                                 trans->bytes_reserved, NULL);
 946         trans->bytes_reserved = 0;
 947 }
 948
 949 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 950                                    int throttle)
 951 {
 952         struct btrfs_fs_info *info = trans->fs_info;
 953         struct btrfs_transaction *cur_trans = trans->transaction;
 954         int err = 0;
 955
 956         if (refcount_read(&trans->use_count) > 1) {
 957                 refcount_dec(&trans->use_count);
 958                 trans->block_rsv = trans->orig_rsv;
 959                 return 0;
 960         }
 961
 962         btrfs_trans_release_metadata(trans);
 963         trans->block_rsv = NULL;
 964
 965         btrfs_create_pending_block_groups(trans);
 966
 967         btrfs_trans_release_chunk_metadata(trans);
 968
 969         if (trans->type & __TRANS_FREEZABLE)
 970                 sb_end_intwrite(info->sb);
 971
 972         WARN_ON(cur_trans != info->running_transaction);
 973         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 974         atomic_dec(&cur_trans->num_writers);
 975         extwriter_counter_dec(cur_trans, trans->type);
 976
 977         cond_wake_up(&cur_trans->writer_wait);
 978         btrfs_put_transaction(cur_trans);
 979
 980         if (current->journal_info == trans)
 981                 current->journal_info = NULL;
 982
 983         if (throttle)
 984                 btrfs_run_delayed_iputs(info);
 985
 986         if (TRANS_ABORTED(trans) ||
 987             test_bit(BTRFS_FS_STATE_ERROR, &info->fs_state)) {
 988                 wake_up_process(info->transaction_kthread);
 989                 if (TRANS_ABORTED(trans))
 990                         err = trans->aborted;
 991                 else
 992                         err = -EROFS;
 993         }
 994
 995         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 996         return err;
 997 }
 998
 999 int btrfs_end_transaction(struct btrfs_trans_handle *trans)
1000 {
1001         return __btrfs_end_transaction(trans, 0);
1002 }
1003
1004 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans)
1005 {
1006         return __btrfs_end_transaction(trans, 1);
1007 }
1008
1009 /*
1010  * when btree blocks are allocated, they have some corresponding bits set for
1011  * them in one of two extent_io trees.  This is used to make sure all of
1012  * those extents are sent to disk but does not wait on them
1013  */
1014 int btrfs_write_marked_extents(struct btrfs_fs_info *fs_info,
1015                                struct extent_io_tree *dirty_pages, int mark)
1016 {
1017         int err = 0;
1018         int werr = 0;
1019         struct address_space *mapping = fs_info->btree_inode->i_mapping;
1020         struct extent_state *cached_state = NULL;
1021         u64 start = 0;
1022         u64 end;
1023
1024         atomic_inc(&BTRFS_I(fs_info->btree_inode)->sync_writers);
1025         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
1026                                       mark, &cached_state)) {
1027                 bool wait_writeback = false;
1028
1029                 err = convert_extent_bit(dirty_pages, start, end,
1030                                          EXTENT_NEED_WAIT,
1031                                          mark, &cached_state);
1032                 /*
1033                  * convert_extent_bit can return -ENOMEM, which is most of the
1034                  * time a temporary error. So when it happens, ignore the error
1035                  * and wait for writeback of this range to finish - because we
1036                  * failed to set the bit EXTENT_NEED_WAIT for the range, a call
1037                  * to __btrfs_wait_marked_extents() would not know that
1038                  * writeback for this range started and therefore wouldn't
1039                  * wait for it to finish - we don't want to commit a
1040                  * superblock that points to btree nodes/leafs for which
1041                  * writeback hasn't finished yet (and without errors).
1042                  * We cleanup any entries left in the io tree when committing
1043                  * the transaction (through extent_io_tree_release()).
1044                  */
1045                 if (err == -ENOMEM) {
1046                         err = 0;
1047                         wait_writeback = true;
1048                 }
1049                 if (!err)
1050                         err = filemap_fdatawrite_range(mapping, start, end);
1051                 if (err)
1052                         werr = err;
1053                 else if (wait_writeback)
1054                         werr = filemap_fdatawait_range(mapping, start, end);
1055                 free_extent_state(cached_state);
1056                 cached_state = NULL;
1057                 cond_resched();
1058                 start = end + 1;
1059         }
1060         atomic_dec(&BTRFS_I(fs_info->btree_inode)->sync_writers);
1061         return werr;
1062 }
1063
1064 /*
1065  * when btree blocks are allocated, they have some corresponding bits set for
1066  * them in one of two extent_io trees.  This is used to make sure all of
1067  * those extents are on disk for transaction or log commit.  We wait
1068  * on all the pages and clear them from the dirty pages state tree
1069  */
1070 static int __btrfs_wait_marked_extents(struct btrfs_fs_info *fs_info,
1071                                        struct extent_io_tree *dirty_pages)
1072 {
1073         int err = 0;
1074         int werr = 0;
1075         struct address_space *mapping = fs_info->btree_inode->i_mapping;
1076         struct extent_state *cached_state = NULL;
1077         u64 start = 0;
1078         u64 end;
1079
1080         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
1081                                       EXTENT_NEED_WAIT, &cached_state)) {
1082                 /*
1083                  * Ignore -ENOMEM errors returned by clear_extent_bit().
1084                  * When committing the transaction, we'll remove any entries
1085                  * left in the io tree. For a log commit, we don't remove them
1086                  * after committing the log because the tree can be accessed
1087                  * concurrently - we do it only at transaction commit time when
1088                  * it's safe to do it (through extent_io_tree_release()).
1089                  */
1090                 err = clear_extent_bit(dirty_pages, start, end,
1091                                        EXTENT_NEED_WAIT, 0, 0, &cached_state);
1092                 if (err == -ENOMEM)
1093                         err = 0;
1094                 if (!err)
1095                         err = filemap_fdatawait_range(mapping, start, end);
1096                 if (err)
1097                         werr = err;
1098                 free_extent_state(cached_state);
1099                 cached_state = NULL;
1100                 cond_resched();
1101                 start = end + 1;
1102         }
1103         if (err)
1104                 werr = err;
1105         return werr;
1106 }
1107
1108 static int btrfs_wait_extents(struct btrfs_fs_info *fs_info,
1109                        struct extent_io_tree *dirty_pages)
1110 {
1111         bool errors = false;
1112         int err;
1113
1114         err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
1115         if (test_and_clear_bit(BTRFS_FS_BTREE_ERR, &fs_info->flags))
1116                 errors = true;
1117
1118         if (errors && !err)
1119                 err = -EIO;
1120         return err;
1121 }
1122
1123 int btrfs_wait_tree_log_extents(struct btrfs_root *log_root, int mark)
1124 {
1125         struct btrfs_fs_info *fs_info = log_root->fs_info;
1126         struct extent_io_tree *dirty_pages = &log_root->dirty_log_pages;
1127         bool errors = false;
1128         int err;
1129
1130         ASSERT(log_root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID);
1131
1132         err = __btrfs_wait_marked_extents(fs_info, dirty_pages);
1133         if ((mark & EXTENT_DIRTY) &&
1134             test_and_clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags))
1135                 errors = true;
1136
1137         if ((mark & EXTENT_NEW) &&
1138             test_and_clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags))
1139                 errors = true;
1140
1141         if (errors && !err)
1142                 err = -EIO;
1143         return err;
1144 }
1145
1146 /*
1147  * When btree blocks are allocated the corresponding extents are marked dirty.
1148  * This function ensures such extents are persisted on disk for transaction or
1149  * log commit.
1150  *
1151  * @trans: transaction whose dirty pages we'd like to write
1152  */
1153 static int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans)
1154 {
1155         int ret;
1156         int ret2;
1157         struct extent_io_tree *dirty_pages = &trans->transaction->dirty_pages;
1158         struct btrfs_fs_info *fs_info = trans->fs_info;
1159         struct blk_plug plug;
1160
1161         blk_start_plug(&plug);
1162         ret = btrfs_write_marked_extents(fs_info, dirty_pages, EXTENT_DIRTY);
1163         blk_finish_plug(&plug);
1164         ret2 = btrfs_wait_extents(fs_info, dirty_pages);
1165
1166         extent_io_tree_release(&trans->transaction->dirty_pages);
1167
1168         if (ret)
1169                 return ret;
1170         else if (ret2)
1171                 return ret2;
1172         else
1173                 return 0;
1174 }
1175
1176 /*
1177  * this is used to update the root pointer in the tree of tree roots.
1178  *
1179  * But, in the case of the extent allocation tree, updating the root
1180  * pointer may allocate blocks which may change the root of the extent
1181  * allocation tree.
1182  *
1183  * So, this loops and repeats and makes sure the cowonly root didn't
1184  * change while the root pointer was being updated in the metadata.
1185  */
1186 static int update_cowonly_root(struct btrfs_trans_handle *trans,
1187                                struct btrfs_root *root)
1188 {
1189         int ret;
1190         u64 old_root_bytenr;
1191         u64 old_root_used;
1192         struct btrfs_fs_info *fs_info = root->fs_info;
1193         struct btrfs_root *tree_root = fs_info->tree_root;
1194
1195         old_root_used = btrfs_root_used(&root->root_item);
1196
1197         while (1) {
1198                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
1199                 if (old_root_bytenr == root->node->start &&
1200                     old_root_used == btrfs_root_used(&root->root_item))
1201                         break;
1202
1203                 btrfs_set_root_node(&root->root_item, root->node);
1204                 ret = btrfs_update_root(trans, tree_root,
1205                                         &root->root_key,
1206                                         &root->root_item);
1207                 if (ret)
1208                         return ret;
1209
1210                 old_root_used = btrfs_root_used(&root->root_item);
1211         }
1212
1213         return 0;
1214 }
1215
1216 /*
1217  * update all the cowonly tree roots on disk
1218  *
1219  * The error handling in this function may not be obvious. Any of the
1220  * failures will cause the file system to go offline. We still need
1221  * to clean up the delayed refs.
1222  */
1223 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans)
1224 {
1225         struct btrfs_fs_info *fs_info = trans->fs_info;
1226         struct list_head *dirty_bgs = &trans->transaction->dirty_bgs;
1227         struct list_head *io_bgs = &trans->transaction->io_bgs;
1228         struct list_head *next;
1229         struct extent_buffer *eb;
1230         int ret;
1231
1232         eb = btrfs_lock_root_node(fs_info->tree_root);
1233         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
1234                               0, &eb, BTRFS_NESTING_COW);
1235         btrfs_tree_unlock(eb);
1236         free_extent_buffer(eb);
1237
1238         if (ret)
1239                 return ret;
1240
1241         ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
1242         if (ret)
1243                 return ret;
1244
1245         ret = btrfs_run_dev_stats(trans);
1246         if (ret)
1247                 return ret;
1248         ret = btrfs_run_dev_replace(trans);
1249         if (ret)
1250                 return ret;
1251         ret = btrfs_run_qgroups(trans);
1252         if (ret)
1253                 return ret;
1254
1255         ret = btrfs_setup_space_cache(trans);
1256         if (ret)
1257                 return ret;
1258
1259         /* run_qgroups might have added some more refs */
1260         ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
1261         if (ret)
1262                 return ret;
1263 again:
1264         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
1265                 struct btrfs_root *root;
1266                 next = fs_info->dirty_cowonly_roots.next;
1267                 list_del_init(next);
1268                 root = list_entry(next, struct btrfs_root, dirty_list);
1269                 clear_bit(BTRFS_ROOT_DIRTY, &root->state);
1270
1271                 if (root != fs_info->extent_root)
1272                         list_add_tail(&root->dirty_list,
1273                                       &trans->transaction->switch_commits);
1274                 ret = update_cowonly_root(trans, root);
1275                 if (ret)
1276                         return ret;
1277                 ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
1278                 if (ret)
1279                         return ret;
1280         }
1281
1282         while (!list_empty(dirty_bgs) || !list_empty(io_bgs)) {
1283                 ret = btrfs_write_dirty_block_groups(trans);
1284                 if (ret)
1285                         return ret;
1286                 ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
1287                 if (ret)
1288                         return ret;
1289         }
1290
1291         if (!list_empty(&fs_info->dirty_cowonly_roots))
1292                 goto again;
1293
1294         list_add_tail(&fs_info->extent_root->dirty_list,
1295                       &trans->transaction->switch_commits);
1296
1297         /* Update dev-replace pointer once everything is committed */
1298         fs_info->dev_replace.committed_cursor_left =
1299                 fs_info->dev_replace.cursor_left_last_write_of_item;
1300
1301         return 0;
1302 }
1303
1304 /*
1305  * dead roots are old snapshots that need to be deleted.  This allocates
1306  * a dirty root struct and adds it into the list of dead roots that need to
1307  * be deleted
1308  */
1309 void btrfs_add_dead_root(struct btrfs_root *root)
1310 {
1311         struct btrfs_fs_info *fs_info = root->fs_info;
1312
1313         spin_lock(&fs_info->trans_lock);
1314         if (list_empty(&root->root_list)) {
1315                 btrfs_grab_root(root);
1316                 list_add_tail(&root->root_list, &fs_info->dead_roots);
1317         }
1318         spin_unlock(&fs_info->trans_lock);
1319 }
1320
1321 /*
1322  * update all the cowonly tree roots on disk
1323  */
1324 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans)
1325 {
1326         struct btrfs_fs_info *fs_info = trans->fs_info;
1327         struct btrfs_root *gang[8];
1328         int i;
1329         int ret;
1330
1331         spin_lock(&fs_info->fs_roots_radix_lock);
1332         while (1) {
1333                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
1334                                                  (void **)gang, 0,
1335                                                  ARRAY_SIZE(gang),
1336                                                  BTRFS_ROOT_TRANS_TAG);
1337                 if (ret == 0)
1338                         break;
1339                 for (i = 0; i < ret; i++) {
1340                         struct btrfs_root *root = gang[i];
1341                         int ret2;
1342
1343                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
1344                                         (unsigned long)root->root_key.objectid,
1345                                         BTRFS_ROOT_TRANS_TAG);
1346                         btrfs_qgroup_free_meta_all_pertrans(root);
1347                         spin_unlock(&fs_info->fs_roots_radix_lock);
1348
1349                         btrfs_free_log(trans, root);
1350                         btrfs_update_reloc_root(trans, root);
1351
1352                         btrfs_save_ino_cache(root, trans);
1353
1354                         /* see comments in should_cow_block() */
1355                         clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1356                         smp_mb__after_atomic();
1357
1358                         if (root->commit_root != root->node) {
1359                                 list_add_tail(&root->dirty_list,
1360                                         &trans->transaction->switch_commits);
1361                                 btrfs_set_root_node(&root->root_item,
1362                                                     root->node);
1363                         }
1364
1365                         ret2 = btrfs_update_root(trans, fs_info->tree_root,
1366                                                 &root->root_key,
1367                                                 &root->root_item);
1368                         if (ret2)
1369                                 return ret2;
1370                         spin_lock(&fs_info->fs_roots_radix_lock);
1371                 }
1372         }
1373         spin_unlock(&fs_info->fs_roots_radix_lock);
1374         return 0;
1375 }
1376
1377 /*
1378  * defrag a given btree.
1379  * Every leaf in the btree is read and defragged.
1380  */
1381 int btrfs_defrag_root(struct btrfs_root *root)
1382 {
1383         struct btrfs_fs_info *info = root->fs_info;
1384         struct btrfs_trans_handle *trans;
1385         int ret;
1386
1387         if (test_and_set_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state))
1388                 return 0;
1389
1390         while (1) {
1391                 trans = btrfs_start_transaction(root, 0);
1392                 if (IS_ERR(trans)) {
1393                         ret = PTR_ERR(trans);
1394                         break;
1395                 }
1396
1397                 ret = btrfs_defrag_leaves(trans, root);
1398
1399                 btrfs_end_transaction(trans);
1400                 btrfs_btree_balance_dirty(info);
1401                 cond_resched();
1402
1403                 if (btrfs_fs_closing(info) || ret != -EAGAIN)
1404                         break;
1405
1406                 if (btrfs_defrag_cancelled(info)) {
1407                         btrfs_debug(info, "defrag_root cancelled");
1408                         ret = -EAGAIN;
1409                         break;
1410                 }
1411         }
1412         clear_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state);
1413         return ret;
1414 }
1415
1416 /*
1417  * Do all special snapshot related qgroup dirty hack.
1418  *
1419  * Will do all needed qgroup inherit and dirty hack like switch commit
1420  * roots inside one transaction and write all btree into disk, to make
1421  * qgroup works.
1422  */
1423 static int qgroup_account_snapshot(struct btrfs_trans_handle *trans,
1424                                    struct btrfs_root *src,
1425                                    struct btrfs_root *parent,
1426                                    struct btrfs_qgroup_inherit *inherit,
1427                                    u64 dst_objectid)
1428 {
1429         struct btrfs_fs_info *fs_info = src->fs_info;
1430         int ret;
1431
1432         /*
1433          * Save some performance in the case that qgroups are not
1434          * enabled. If this check races with the ioctl, rescan will
1435          * kick in anyway.
1436          */
1437         if (!test_bit(BTRFS_FS_QUOTA_ENABLED, &fs_info->flags))
1438                 return 0;
1439
1440         /*
1441          * Ensure dirty @src will be committed.  Or, after coming
1442          * commit_fs_roots() and switch_commit_roots(), any dirty but not
1443          * recorded root will never be updated again, causing an outdated root
1444          * item.
1445          */
1446         record_root_in_trans(trans, src, 1);
1447
1448         /*
1449          * We are going to commit transaction, see btrfs_commit_transaction()
1450          * comment for reason locking tree_log_mutex
1451          */
1452         mutex_lock(&fs_info->tree_log_mutex);
1453
1454         ret = commit_fs_roots(trans);
1455         if (ret)
1456                 goto out;
1457         ret = btrfs_qgroup_account_extents(trans);
1458         if (ret < 0)
1459                 goto out;
1460
1461         /* Now qgroup are all updated, we can inherit it to new qgroups */
1462         ret = btrfs_qgroup_inherit(trans, src->root_key.objectid, dst_objectid,
1463                                    inherit);
1464         if (ret < 0)
1465                 goto out;
1466
1467         /*
1468          * Now we do a simplified commit transaction, which will:
1469          * 1) commit all subvolume and extent tree
1470          *    To ensure all subvolume and extent tree have a valid
1471          *    commit_root to accounting later insert_dir_item()
1472          * 2) write all btree blocks onto disk
1473          *    This is to make sure later btree modification will be cowed
1474          *    Or commit_root can be populated and cause wrong qgroup numbers
1475          * In this simplified commit, we don't really care about other trees
1476          * like chunk and root tree, as they won't affect qgroup.
1477          * And we don't write super to avoid half committed status.
1478          */
1479         ret = commit_cowonly_roots(trans);
1480         if (ret)
1481                 goto out;
1482         switch_commit_roots(trans);
1483         ret = btrfs_write_and_wait_transaction(trans);
1484         if (ret)
1485                 btrfs_handle_fs_error(fs_info, ret,
1486                         "Error while writing out transaction for qgroup");
1487
1488 out:
1489         mutex_unlock(&fs_info->tree_log_mutex);
1490
1491         /*
1492          * Force parent root to be updated, as we recorded it before so its
1493          * last_trans == cur_transid.
1494          * Or it won't be committed again onto disk after later
1495          * insert_dir_item()
1496          */
1497         if (!ret)
1498                 record_root_in_trans(trans, parent, 1);
1499         return ret;
1500 }
1501
1502 /*
1503  * new snapshots need to be created at a very specific time in the
1504  * transaction commit.  This does the actual creation.
1505  *
1506  * Note:
1507  * If the error which may affect the commitment of the current transaction
1508  * happens, we should return the error number. If the error which just affect
1509  * the creation of the pending snapshots, just return 0.
1510  */
1511 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
1512                                    struct btrfs_pending_snapshot *pending)
1513 {
1514
1515         struct btrfs_fs_info *fs_info = trans->fs_info;
1516         struct btrfs_key key;
1517         struct btrfs_root_item *new_root_item;
1518         struct btrfs_root *tree_root = fs_info->tree_root;
1519         struct btrfs_root *root = pending->root;
1520         struct btrfs_root *parent_root;
1521         struct btrfs_block_rsv *rsv;
1522         struct inode *parent_inode;
1523         struct btrfs_path *path;
1524         struct btrfs_dir_item *dir_item;
1525         struct dentry *dentry;
1526         struct extent_buffer *tmp;
1527         struct extent_buffer *old;
1528         struct timespec64 cur_time;
1529         int ret = 0;
1530         u64 to_reserve = 0;
1531         u64 index = 0;
1532         u64 objectid;
1533         u64 root_flags;
1534
1535         ASSERT(pending->path);
1536         path = pending->path;
1537
1538         ASSERT(pending->root_item);
1539         new_root_item = pending->root_item;
1540
1541         pending->error = btrfs_find_free_objectid(tree_root, &objectid);
1542         if (pending->error)
1543                 goto no_free_objectid;
1544
1545         /*
1546          * Make qgroup to skip current new snapshot's qgroupid, as it is
1547          * accounted by later btrfs_qgroup_inherit().
1548          */
1549         btrfs_set_skip_qgroup(trans, objectid);
1550
1551         btrfs_reloc_pre_snapshot(pending, &to_reserve);
1552
1553         if (to_reserve > 0) {
1554                 pending->error = btrfs_block_rsv_add(root,
1555                                                      &pending->block_rsv,
1556                                                      to_reserve,
1557                                                      BTRFS_RESERVE_NO_FLUSH);
1558                 if (pending->error)
1559                         goto clear_skip_qgroup;
1560         }
1561
1562         key.objectid = objectid;
1563         key.offset = (u64)-1;
1564         key.type = BTRFS_ROOT_ITEM_KEY;
1565
1566         rsv = trans->block_rsv;
1567         trans->block_rsv = &pending->block_rsv;
1568         trans->bytes_reserved = trans->block_rsv->reserved;
1569         trace_btrfs_space_reservation(fs_info, "transaction",
1570                                       trans->transid,
1571                                       trans->bytes_reserved, 1);
1572         dentry = pending->dentry;
1573         parent_inode = pending->dir;
1574         parent_root = BTRFS_I(parent_inode)->root;
1575         record_root_in_trans(trans, parent_root, 0);
1576
1577         cur_time = current_time(parent_inode);
1578
1579         /*
1580          * insert the directory item
1581          */
1582         ret = btrfs_set_inode_index(BTRFS_I(parent_inode), &index);
1583         BUG_ON(ret); /* -ENOMEM */
1584
1585         /* check if there is a file/dir which has the same name. */
1586         dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1587                                          btrfs_ino(BTRFS_I(parent_inode)),
1588                                          dentry->d_name.name,
1589                                          dentry->d_name.len, 0);
1590         if (dir_item != NULL && !IS_ERR(dir_item)) {
1591                 pending->error = -EEXIST;
1592                 goto dir_item_existed;
1593         } else if (IS_ERR(dir_item)) {
1594                 ret = PTR_ERR(dir_item);
1595                 btrfs_abort_transaction(trans, ret);
1596                 goto fail;
1597         }
1598         btrfs_release_path(path);
1599
1600         /*
1601          * pull in the delayed directory update
1602          * and the delayed inode item
1603          * otherwise we corrupt the FS during
1604          * snapshot
1605          */
1606         ret = btrfs_run_delayed_items(trans);
1607         if (ret) {      /* Transaction aborted */
1608                 btrfs_abort_transaction(trans, ret);
1609                 goto fail;
1610         }
1611
1612         record_root_in_trans(trans, root, 0);
1613         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1614         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1615         btrfs_check_and_init_root_item(new_root_item);
1616
1617         root_flags = btrfs_root_flags(new_root_item);
1618         if (pending->readonly)
1619                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1620         else
1621                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1622         btrfs_set_root_flags(new_root_item, root_flags);
1623
1624         btrfs_set_root_generation_v2(new_root_item,
1625                         trans->transid);
1626         generate_random_guid(new_root_item->uuid);
1627         memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1628                         BTRFS_UUID_SIZE);
1629         if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
1630                 memset(new_root_item->received_uuid, 0,
1631                        sizeof(new_root_item->received_uuid));
1632                 memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1633                 memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1634                 btrfs_set_root_stransid(new_root_item, 0);
1635                 btrfs_set_root_rtransid(new_root_item, 0);
1636         }
1637         btrfs_set_stack_timespec_sec(&new_root_item->otime, cur_time.tv_sec);
1638         btrfs_set_stack_timespec_nsec(&new_root_item->otime, cur_time.tv_nsec);
1639         btrfs_set_root_otransid(new_root_item, trans->transid);
1640
1641         old = btrfs_lock_root_node(root);
1642         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old,
1643                               BTRFS_NESTING_COW);
1644         if (ret) {
1645                 btrfs_tree_unlock(old);
1646                 free_extent_buffer(old);
1647                 btrfs_abort_transaction(trans, ret);
1648                 goto fail;
1649         }
1650
1651         btrfs_set_lock_blocking_write(old);
1652
1653         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1654         /* clean up in any case */
1655         btrfs_tree_unlock(old);
1656         free_extent_buffer(old);
1657         if (ret) {
1658                 btrfs_abort_transaction(trans, ret);
1659                 goto fail;
1660         }
1661         /* see comments in should_cow_block() */
1662         set_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1663         smp_wmb();
1664
1665         btrfs_set_root_node(new_root_item, tmp);
1666         /* record when the snapshot was created in key.offset */
1667         key.offset = trans->transid;
1668         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1669         btrfs_tree_unlock(tmp);
1670         free_extent_buffer(tmp);
1671         if (ret) {
1672                 btrfs_abort_transaction(trans, ret);
1673                 goto fail;
1674         }
1675
1676         /*
1677          * insert root back/forward references
1678          */
1679         ret = btrfs_add_root_ref(trans, objectid,
1680                                  parent_root->root_key.objectid,
1681                                  btrfs_ino(BTRFS_I(parent_inode)), index,
1682                                  dentry->d_name.name, dentry->d_name.len);
1683         if (ret) {
1684                 btrfs_abort_transaction(trans, ret);
1685                 goto fail;
1686         }
1687
1688         key.offset = (u64)-1;
1689         pending->snap = btrfs_get_new_fs_root(fs_info, objectid, pending->anon_dev);
1690         if (IS_ERR(pending->snap)) {
1691                 ret = PTR_ERR(pending->snap);
1692                 pending->snap = NULL;
1693                 btrfs_abort_transaction(trans, ret);
1694                 goto fail;
1695         }
1696
1697         ret = btrfs_reloc_post_snapshot(trans, pending);
1698         if (ret) {
1699                 btrfs_abort_transaction(trans, ret);
1700                 goto fail;
1701         }
1702
1703         ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
1704         if (ret) {
1705                 btrfs_abort_transaction(trans, ret);
1706                 goto fail;
1707         }
1708
1709         /*
1710          * Do special qgroup accounting for snapshot, as we do some qgroup
1711          * snapshot hack to do fast snapshot.
1712          * To co-operate with that hack, we do hack again.
1713          * Or snapshot will be greatly slowed down by a subtree qgroup rescan
1714          */
1715         ret = qgroup_account_snapshot(trans, root, parent_root,
1716                                       pending->inherit, objectid);
1717         if (ret < 0)
1718                 goto fail;
1719
1720         ret = btrfs_insert_dir_item(trans, dentry->d_name.name,
1721                                     dentry->d_name.len, BTRFS_I(parent_inode),
1722                                     &key, BTRFS_FT_DIR, index);
1723         /* We have check then name at the beginning, so it is impossible. */
1724         BUG_ON(ret == -EEXIST || ret == -EOVERFLOW);
1725         if (ret) {
1726                 btrfs_abort_transaction(trans, ret);
1727                 goto fail;
1728         }
1729
1730         btrfs_i_size_write(BTRFS_I(parent_inode), parent_inode->i_size +
1731                                          dentry->d_name.len * 2);
1732         parent_inode->i_mtime = parent_inode->i_ctime =
1733                 current_time(parent_inode);
1734         ret = btrfs_update_inode_fallback(trans, parent_root, parent_inode);
1735         if (ret) {
1736                 btrfs_abort_transaction(trans, ret);
1737                 goto fail;
1738         }
1739         ret = btrfs_uuid_tree_add(trans, new_root_item->uuid,
1740                                   BTRFS_UUID_KEY_SUBVOL,
1741                                   objectid);
1742         if (ret) {
1743                 btrfs_abort_transaction(trans, ret);
1744                 goto fail;
1745         }
1746         if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
1747                 ret = btrfs_uuid_tree_add(trans, new_root_item->received_uuid,
1748                                           BTRFS_UUID_KEY_RECEIVED_SUBVOL,
1749                                           objectid);
1750                 if (ret && ret != -EEXIST) {
1751                         btrfs_abort_transaction(trans, ret);
1752                         goto fail;
1753                 }
1754         }
1755
1756         ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
1757         if (ret) {
1758                 btrfs_abort_transaction(trans, ret);
1759                 goto fail;
1760         }
1761
1762 fail:
1763         pending->error = ret;
1764 dir_item_existed:
1765         trans->block_rsv = rsv;
1766         trans->bytes_reserved = 0;
1767 clear_skip_qgroup:
1768         btrfs_clear_skip_qgroup(trans);
1769 no_free_objectid:
1770         kfree(new_root_item);
1771         pending->root_item = NULL;
1772         btrfs_free_path(path);
1773         pending->path = NULL;
1774
1775         return ret;
1776 }
1777
1778 /*
1779  * create all the snapshots we've scheduled for creation
1780  */
1781 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans)
1782 {
1783         struct btrfs_pending_snapshot *pending, *next;
1784         struct list_head *head = &trans->transaction->pending_snapshots;
1785         int ret = 0;
1786
1787         list_for_each_entry_safe(pending, next, head, list) {
1788                 list_del(&pending->list);
1789                 ret = create_pending_snapshot(trans, pending);
1790                 if (ret)
1791                         break;
1792         }
1793         return ret;
1794 }
1795
1796 static void update_super_roots(struct btrfs_fs_info *fs_info)
1797 {
1798         struct btrfs_root_item *root_item;
1799         struct btrfs_super_block *super;
1800
1801         super = fs_info->super_copy;
1802
1803         root_item = &fs_info->chunk_root->root_item;
1804         super->chunk_root = root_item->bytenr;
1805         super->chunk_root_generation = root_item->generation;
1806         super->chunk_root_level = root_item->level;
1807
1808         root_item = &fs_info->tree_root->root_item;
1809         super->root = root_item->bytenr;
1810         super->generation = root_item->generation;
1811         super->root_level = root_item->level;
1812         if (btrfs_test_opt(fs_info, SPACE_CACHE))
1813                 super->cache_generation = root_item->generation;
1814         if (test_bit(BTRFS_FS_UPDATE_UUID_TREE_GEN, &fs_info->flags))
1815                 super->uuid_tree_generation = root_item->generation;
1816 }
1817
1818 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1819 {
1820         struct btrfs_transaction *trans;
1821         int ret = 0;
1822
1823         spin_lock(&info->trans_lock);
1824         trans = info->running_transaction;
1825         if (trans)
1826                 ret = (trans->state >= TRANS_STATE_COMMIT_START);
1827         spin_unlock(&info->trans_lock);
1828         return ret;
1829 }
1830
1831 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1832 {
1833         struct btrfs_transaction *trans;
1834         int ret = 0;
1835
1836         spin_lock(&info->trans_lock);
1837         trans = info->running_transaction;
1838         if (trans)
1839                 ret = is_transaction_blocked(trans);
1840         spin_unlock(&info->trans_lock);
1841         return ret;
1842 }
1843
1844 /*
1845  * wait for the current transaction commit to start and block subsequent
1846  * transaction joins
1847  */
1848 static void wait_current_trans_commit_start(struct btrfs_fs_info *fs_info,
1849                                             struct btrfs_transaction *trans)
1850 {
1851         wait_event(fs_info->transaction_blocked_wait,
1852                    trans->state >= TRANS_STATE_COMMIT_START ||
1853                    TRANS_ABORTED(trans));
1854 }
1855
1856 /*
1857  * wait for the current transaction to start and then become unblocked.
1858  * caller holds ref.
1859  */
1860 static void wait_current_trans_commit_start_and_unblock(
1861                                         struct btrfs_fs_info *fs_info,
1862                                         struct btrfs_transaction *trans)
1863 {
1864         wait_event(fs_info->transaction_wait,
1865                    trans->state >= TRANS_STATE_UNBLOCKED ||
1866                    TRANS_ABORTED(trans));
1867 }
1868
1869 /*
1870  * commit transactions asynchronously. once btrfs_commit_transaction_async
1871  * returns, any subsequent transaction will not be allowed to join.
1872  */
1873 struct btrfs_async_commit {
1874         struct btrfs_trans_handle *newtrans;
1875         struct work_struct work;
1876 };
1877
1878 static void do_async_commit(struct work_struct *work)
1879 {
1880         struct btrfs_async_commit *ac =
1881                 container_of(work, struct btrfs_async_commit, work);
1882
1883         /*
1884          * We've got freeze protection passed with the transaction.
1885          * Tell lockdep about it.
1886          */
1887         if (ac->newtrans->type & __TRANS_FREEZABLE)
1888                 __sb_writers_acquired(ac->newtrans->fs_info->sb, SB_FREEZE_FS);
1889
1890         current->journal_info = ac->newtrans;
1891
1892         btrfs_commit_transaction(ac->newtrans);
1893         kfree(ac);
1894 }
1895
1896 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1897                                    int wait_for_unblock)
1898 {
1899         struct btrfs_fs_info *fs_info = trans->fs_info;
1900         struct btrfs_async_commit *ac;
1901         struct btrfs_transaction *cur_trans;
1902
1903         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1904         if (!ac)
1905                 return -ENOMEM;
1906
1907         INIT_WORK(&ac->work, do_async_commit);
1908         ac->newtrans = btrfs_join_transaction(trans->root);
1909         if (IS_ERR(ac->newtrans)) {
1910                 int err = PTR_ERR(ac->newtrans);
1911                 kfree(ac);
1912                 return err;
1913         }
1914
1915         /* take transaction reference */
1916         cur_trans = trans->transaction;
1917         refcount_inc(&cur_trans->use_count);
1918
1919         btrfs_end_transaction(trans);
1920
1921         /*
1922          * Tell lockdep we've released the freeze rwsem, since the
1923          * async commit thread will be the one to unlock it.
1924          */
1925         if (ac->newtrans->type & __TRANS_FREEZABLE)
1926                 __sb_writers_release(fs_info->sb, SB_FREEZE_FS);
1927
1928         schedule_work(&ac->work);
1929
1930         /* wait for transaction to start and unblock */
1931         if (wait_for_unblock)
1932                 wait_current_trans_commit_start_and_unblock(fs_info, cur_trans);
1933         else
1934                 wait_current_trans_commit_start(fs_info, cur_trans);
1935
1936         if (current->journal_info == trans)
1937                 current->journal_info = NULL;
1938
1939         btrfs_put_transaction(cur_trans);
1940         return 0;
1941 }
1942
1943
1944 static void cleanup_transaction(struct btrfs_trans_handle *trans, int err)
1945 {
1946         struct btrfs_fs_info *fs_info = trans->fs_info;
1947         struct btrfs_transaction *cur_trans = trans->transaction;
1948
1949         WARN_ON(refcount_read(&trans->use_count) > 1);
1950
1951         btrfs_abort_transaction(trans, err);
1952
1953         spin_lock(&fs_info->trans_lock);
1954
1955         /*
1956          * If the transaction is removed from the list, it means this
1957          * transaction has been committed successfully, so it is impossible
1958          * to call the cleanup function.
1959          */
1960         BUG_ON(list_empty(&cur_trans->list));
1961
1962         if (cur_trans == fs_info->running_transaction) {
1963                 cur_trans->state = TRANS_STATE_COMMIT_DOING;
1964                 spin_unlock(&fs_info->trans_lock);
1965                 wait_event(cur_trans->writer_wait,
1966                            atomic_read(&cur_trans->num_writers) == 1);
1967
1968                 spin_lock(&fs_info->trans_lock);
1969         }
1970
1971         /*
1972          * Now that we know no one else is still using the transaction we can
1973          * remove the transaction from the list of transactions. This avoids
1974          * the transaction kthread from cleaning up the transaction while some
1975          * other task is still using it, which could result in a use-after-free
1976          * on things like log trees, as it forces the transaction kthread to
1977          * wait for this transaction to be cleaned up by us.
1978          */
1979         list_del_init(&cur_trans->list);
1980
1981         spin_unlock(&fs_info->trans_lock);
1982
1983         btrfs_cleanup_one_transaction(trans->transaction, fs_info);
1984
1985         spin_lock(&fs_info->trans_lock);
1986         if (cur_trans == fs_info->running_transaction)
1987                 fs_info->running_transaction = NULL;
1988         spin_unlock(&fs_info->trans_lock);
1989
1990         if (trans->type & __TRANS_FREEZABLE)
1991                 sb_end_intwrite(fs_info->sb);
1992         btrfs_put_transaction(cur_trans);
1993         btrfs_put_transaction(cur_trans);
1994
1995         trace_btrfs_transaction_commit(trans->root);
1996
1997         if (current->journal_info == trans)
1998                 current->journal_info = NULL;
1999         btrfs_scrub_cancel(fs_info);
2000
2001         kmem_cache_free(btrfs_trans_handle_cachep, trans);
2002 }
2003
2004 /*
2005  * Release reserved delayed ref space of all pending block groups of the
2006  * transaction and remove them from the list
2007  */
2008 static void btrfs_cleanup_pending_block_groups(struct btrfs_trans_handle *trans)
2009 {
2010        struct btrfs_fs_info *fs_info = trans->fs_info;
2011        struct btrfs_block_group *block_group, *tmp;
2012
2013        list_for_each_entry_safe(block_group, tmp, &trans->new_bgs, bg_list) {
2014                btrfs_delayed_refs_rsv_release(fs_info, 1);
2015                list_del_init(&block_group->bg_list);
2016        }
2017 }
2018
2019 static inline int btrfs_start_delalloc_flush(struct btrfs_trans_handle *trans)
2020 {
2021         struct btrfs_fs_info *fs_info = trans->fs_info;
2022
2023         /*
2024          * We use writeback_inodes_sb here because if we used
2025          * btrfs_start_delalloc_roots we would deadlock with fs freeze.
2026          * Currently are holding the fs freeze lock, if we do an async flush
2027          * we'll do btrfs_join_transaction() and deadlock because we need to
2028          * wait for the fs freeze lock.  Using the direct flushing we benefit
2029          * from already being in a transaction and our join_transaction doesn't
2030          * have to re-take the fs freeze lock.
2031          */
2032         if (btrfs_test_opt(fs_info, FLUSHONCOMMIT)) {
2033                 writeback_inodes_sb(fs_info->sb, WB_REASON_SYNC);
2034         } else {
2035                 struct btrfs_pending_snapshot *pending;
2036                 struct list_head *head = &trans->transaction->pending_snapshots;
2037
2038                 /*
2039                  * Flush dellaloc for any root that is going to be snapshotted.
2040                  * This is done to avoid a corrupted version of files, in the
2041                  * snapshots, that had both buffered and direct IO writes (even
2042                  * if they were done sequentially) due to an unordered update of
2043                  * the inode's size on disk.
2044                  */
2045                 list_for_each_entry(pending, head, list) {
2046                         int ret;
2047
2048                         ret = btrfs_start_delalloc_snapshot(pending->root);
2049                         if (ret)
2050                                 return ret;
2051                 }
2052         }
2053         return 0;
2054 }
2055
2056 static inline void btrfs_wait_delalloc_flush(struct btrfs_trans_handle *trans)
2057 {
2058         struct btrfs_fs_info *fs_info = trans->fs_info;
2059
2060         if (btrfs_test_opt(fs_info, FLUSHONCOMMIT)) {
2061                 btrfs_wait_ordered_roots(fs_info, U64_MAX, 0, (u64)-1);
2062         } else {
2063                 struct btrfs_pending_snapshot *pending;
2064                 struct list_head *head = &trans->transaction->pending_snapshots;
2065
2066                 /*
2067                  * Wait for any dellaloc that we started previously for the roots
2068                  * that are going to be snapshotted. This is to avoid a corrupted
2069                  * version of files in the snapshots that had both buffered and
2070                  * direct IO writes (even if they were done sequentially).
2071                  */
2072                 list_for_each_entry(pending, head, list)
2073                         btrfs_wait_ordered_extents(pending->root,
2074                                                    U64_MAX, 0, U64_MAX);
2075         }
2076 }
2077
2078 int btrfs_commit_transaction(struct btrfs_trans_handle *trans)
2079 {
2080         struct btrfs_fs_info *fs_info = trans->fs_info;
2081         struct btrfs_transaction *cur_trans = trans->transaction;
2082         struct btrfs_transaction *prev_trans = NULL;
2083         int ret;
2084
2085         ASSERT(refcount_read(&trans->use_count) == 1);
2086
2087         /*
2088          * Some places just start a transaction to commit it.  We need to make
2089          * sure that if this commit fails that the abort code actually marks the
2090          * transaction as failed, so set trans->dirty to make the abort code do
2091          * the right thing.
2092          */
2093         trans->dirty = true;
2094
2095         /* Stop the commit early if ->aborted is set */
2096         if (TRANS_ABORTED(cur_trans)) {
2097                 ret = cur_trans->aborted;
2098                 btrfs_end_transaction(trans);
2099                 return ret;
2100         }
2101
2102         btrfs_trans_release_metadata(trans);
2103         trans->block_rsv = NULL;
2104
2105         /* make a pass through all the delayed refs we have so far
2106          * any runnings procs may add more while we are here
2107          */
2108         ret = btrfs_run_delayed_refs(trans, 0);
2109         if (ret) {
2110                 btrfs_end_transaction(trans);
2111                 return ret;
2112         }
2113
2114         cur_trans = trans->transaction;
2115
2116         /*
2117          * set the flushing flag so procs in this transaction have to
2118          * start sending their work down.
2119          */
2120         cur_trans->delayed_refs.flushing = 1;
2121         smp_wmb();
2122
2123         btrfs_create_pending_block_groups(trans);
2124
2125         ret = btrfs_run_delayed_refs(trans, 0);
2126         if (ret) {
2127                 btrfs_end_transaction(trans);
2128                 return ret;
2129         }
2130
2131         if (!test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &cur_trans->flags)) {
2132                 int run_it = 0;
2133
2134                 /* this mutex is also taken before trying to set
2135                  * block groups readonly.  We need to make sure
2136                  * that nobody has set a block group readonly
2137                  * after a extents from that block group have been
2138                  * allocated for cache files.  btrfs_set_block_group_ro
2139                  * will wait for the transaction to commit if it
2140                  * finds BTRFS_TRANS_DIRTY_BG_RUN set.
2141                  *
2142                  * The BTRFS_TRANS_DIRTY_BG_RUN flag is also used to make sure
2143                  * only one process starts all the block group IO.  It wouldn't
2144                  * hurt to have more than one go through, but there's no
2145                  * real advantage to it either.
2146                  */
2147                 mutex_lock(&fs_info->ro_block_group_mutex);
2148                 if (!test_and_set_bit(BTRFS_TRANS_DIRTY_BG_RUN,
2149                                       &cur_trans->flags))
2150                         run_it = 1;
2151                 mutex_unlock(&fs_info->ro_block_group_mutex);
2152
2153                 if (run_it) {
2154                         ret = btrfs_start_dirty_block_groups(trans);
2155                         if (ret) {
2156                                 btrfs_end_transaction(trans);
2157                                 return ret;
2158                         }
2159                 }
2160         }
2161
2162         spin_lock(&fs_info->trans_lock);
2163         if (cur_trans->state >= TRANS_STATE_COMMIT_START) {
2164                 spin_unlock(&fs_info->trans_lock);
2165                 refcount_inc(&cur_trans->use_count);
2166                 ret = btrfs_end_transaction(trans);
2167
2168                 wait_for_commit(cur_trans);
2169
2170                 if (TRANS_ABORTED(cur_trans))
2171                         ret = cur_trans->aborted;
2172
2173                 btrfs_put_transaction(cur_trans);
2174
2175                 return ret;
2176         }
2177
2178         cur_trans->state = TRANS_STATE_COMMIT_START;
2179         wake_up(&fs_info->transaction_blocked_wait);
2180
2181         if (cur_trans->list.prev != &fs_info->trans_list) {
2182                 prev_trans = list_entry(cur_trans->list.prev,
2183                                         struct btrfs_transaction, list);
2184                 if (prev_trans->state != TRANS_STATE_COMPLETED) {
2185                         refcount_inc(&prev_trans->use_count);
2186                         spin_unlock(&fs_info->trans_lock);
2187
2188                         wait_for_commit(prev_trans);
2189                         ret = READ_ONCE(prev_trans->aborted);
2190
2191                         btrfs_put_transaction(prev_trans);
2192                         if (ret)
2193                                 goto cleanup_transaction;
2194                 } else {
2195                         spin_unlock(&fs_info->trans_lock);
2196                 }
2197         } else {
2198                 spin_unlock(&fs_info->trans_lock);
2199                 /*
2200                  * The previous transaction was aborted and was already removed
2201                  * from the list of transactions at fs_info->trans_list. So we
2202                  * abort to prevent writing a new superblock that reflects a
2203                  * corrupt state (pointing to trees with unwritten nodes/leafs).
2204                  */
2205                 if (test_bit(BTRFS_FS_STATE_TRANS_ABORTED, &fs_info->fs_state)) {
2206                         ret = -EROFS;
2207                         goto cleanup_transaction;
2208                 }
2209         }
2210
2211         extwriter_counter_dec(cur_trans, trans->type);
2212
2213         ret = btrfs_start_delalloc_flush(trans);
2214         if (ret)
2215                 goto cleanup_transaction;
2216
2217         ret = btrfs_run_delayed_items(trans);
2218         if (ret)
2219                 goto cleanup_transaction;
2220
2221         wait_event(cur_trans->writer_wait,
2222                    extwriter_counter_read(cur_trans) == 0);
2223
2224         /* some pending stuffs might be added after the previous flush. */
2225         ret = btrfs_run_delayed_items(trans);
2226         if (ret)
2227                 goto cleanup_transaction;
2228
2229         btrfs_wait_delalloc_flush(trans);
2230
2231         /*
2232          * Wait for all ordered extents started by a fast fsync that joined this
2233          * transaction. Otherwise if this transaction commits before the ordered
2234          * extents complete we lose logged data after a power failure.
2235          */
2236         wait_event(cur_trans->pending_wait,
2237                    atomic_read(&cur_trans->pending_ordered) == 0);
2238
2239         btrfs_scrub_pause(fs_info);
2240         /*
2241          * Ok now we need to make sure to block out any other joins while we
2242          * commit the transaction.  We could have started a join before setting
2243          * COMMIT_DOING so make sure to wait for num_writers to == 1 again.
2244          */
2245         spin_lock(&fs_info->trans_lock);
2246         cur_trans->state = TRANS_STATE_COMMIT_DOING;
2247         spin_unlock(&fs_info->trans_lock);
2248         wait_event(cur_trans->writer_wait,
2249                    atomic_read(&cur_trans->num_writers) == 1);
2250
2251         if (TRANS_ABORTED(cur_trans)) {
2252                 ret = cur_trans->aborted;
2253                 goto scrub_continue;
2254         }
2255         /*
2256          * the reloc mutex makes sure that we stop
2257          * the balancing code from coming in and moving
2258          * extents around in the middle of the commit
2259          */
2260         mutex_lock(&fs_info->reloc_mutex);
2261
2262         /*
2263          * We needn't worry about the delayed items because we will
2264          * deal with them in create_pending_snapshot(), which is the
2265          * core function of the snapshot creation.
2266          */
2267         ret = create_pending_snapshots(trans);
2268         if (ret)
2269                 goto unlock_reloc;
2270
2271         /*
2272          * We insert the dir indexes of the snapshots and update the inode
2273          * of the snapshots' parents after the snapshot creation, so there
2274          * are some delayed items which are not dealt with. Now deal with
2275          * them.
2276          *
2277          * We needn't worry that this operation will corrupt the snapshots,
2278          * because all the tree which are snapshoted will be forced to COW
2279          * the nodes and leaves.
2280          */
2281         ret = btrfs_run_delayed_items(trans);
2282         if (ret)
2283                 goto unlock_reloc;
2284
2285         ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
2286         if (ret)
2287                 goto unlock_reloc;
2288
2289         /*
2290          * make sure none of the code above managed to slip in a
2291          * delayed item
2292          */
2293         btrfs_assert_delayed_root_empty(fs_info);
2294
2295         WARN_ON(cur_trans != trans->transaction);
2296
2297         /* btrfs_commit_tree_roots is responsible for getting the
2298          * various roots consistent with each other.  Every pointer
2299          * in the tree of tree roots has to point to the most up to date
2300          * root for every subvolume and other tree.  So, we have to keep
2301          * the tree logging code from jumping in and changing any
2302          * of the trees.
2303          *
2304          * At this point in the commit, there can't be any tree-log
2305          * writers, but a little lower down we drop the trans mutex
2306          * and let new people in.  By holding the tree_log_mutex
2307          * from now until after the super is written, we avoid races
2308          * with the tree-log code.
2309          */
2310         mutex_lock(&fs_info->tree_log_mutex);
2311
2312         ret = commit_fs_roots(trans);
2313         if (ret)
2314                 goto unlock_tree_log;
2315
2316         /*
2317          * Since the transaction is done, we can apply the pending changes
2318          * before the next transaction.
2319          */
2320         btrfs_apply_pending_changes(fs_info);
2321
2322         /* commit_fs_roots gets rid of all the tree log roots, it is now
2323          * safe to free the root of tree log roots
2324          */
2325         btrfs_free_log_root_tree(trans, fs_info);
2326
2327         /*
2328          * commit_fs_roots() can call btrfs_save_ino_cache(), which generates
2329          * new delayed refs. Must handle them or qgroup can be wrong.
2330          */
2331         ret = btrfs_run_delayed_refs(trans, (unsigned long)-1);
2332         if (ret)
2333                 goto unlock_tree_log;
2334
2335         /*
2336          * Since fs roots are all committed, we can get a quite accurate
2337          * new_roots. So let's do quota accounting.
2338          */
2339         ret = btrfs_qgroup_account_extents(trans);
2340         if (ret < 0)
2341                 goto unlock_tree_log;
2342
2343         ret = commit_cowonly_roots(trans);
2344         if (ret)
2345                 goto unlock_tree_log;
2346
2347         /*
2348          * The tasks which save the space cache and inode cache may also
2349          * update ->aborted, check it.
2350          */
2351         if (TRANS_ABORTED(cur_trans)) {
2352                 ret = cur_trans->aborted;
2353                 goto unlock_tree_log;
2354         }
2355
2356         cur_trans = fs_info->running_transaction;
2357
2358         btrfs_set_root_node(&fs_info->tree_root->root_item,
2359                             fs_info->tree_root->node);
2360         list_add_tail(&fs_info->tree_root->dirty_list,
2361                       &cur_trans->switch_commits);
2362
2363         btrfs_set_root_node(&fs_info->chunk_root->root_item,
2364                             fs_info->chunk_root->node);
2365         list_add_tail(&fs_info->chunk_root->dirty_list,
2366                       &cur_trans->switch_commits);
2367
2368         switch_commit_roots(trans);
2369
2370         ASSERT(list_empty(&cur_trans->dirty_bgs));
2371         ASSERT(list_empty(&cur_trans->io_bgs));
2372         update_super_roots(fs_info);
2373
2374         btrfs_set_super_log_root(fs_info->super_copy, 0);
2375         btrfs_set_super_log_root_level(fs_info->super_copy, 0);
2376         memcpy(fs_info->super_for_commit, fs_info->super_copy,
2377                sizeof(*fs_info->super_copy));
2378
2379         btrfs_commit_device_sizes(cur_trans);
2380
2381         clear_bit(BTRFS_FS_LOG1_ERR, &fs_info->flags);
2382         clear_bit(BTRFS_FS_LOG2_ERR, &fs_info->flags);
2383
2384         btrfs_trans_release_chunk_metadata(trans);
2385
2386         spin_lock(&fs_info->trans_lock);
2387         cur_trans->state = TRANS_STATE_UNBLOCKED;
2388         fs_info->running_transaction = NULL;
2389         spin_unlock(&fs_info->trans_lock);
2390         mutex_unlock(&fs_info->reloc_mutex);
2391
2392         wake_up(&fs_info->transaction_wait);
2393
2394         ret = btrfs_write_and_wait_transaction(trans);
2395         if (ret) {
2396                 btrfs_handle_fs_error(fs_info, ret,
2397                                       "Error while writing out transaction");
2398                 /*
2399                  * reloc_mutex has been unlocked, tree_log_mutex is still held
2400                  * but we can't jump to unlock_tree_log causing double unlock
2401                  */
2402                 mutex_unlock(&fs_info->tree_log_mutex);
2403                 goto scrub_continue;
2404         }
2405
2406         ret = write_all_supers(fs_info, 0);
2407         /*
2408          * the super is written, we can safely allow the tree-loggers
2409          * to go about their business
2410          */
2411         mutex_unlock(&fs_info->tree_log_mutex);
2412         if (ret)
2413                 goto scrub_continue;
2414
2415         btrfs_finish_extent_commit(trans);
2416
2417         if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &cur_trans->flags))
2418                 btrfs_clear_space_info_full(fs_info);
2419
2420         fs_info->last_trans_committed = cur_trans->transid;
2421         /*
2422          * We needn't acquire the lock here because there is no other task
2423          * which can change it.
2424          */
2425         cur_trans->state = TRANS_STATE_COMPLETED;
2426         wake_up(&cur_trans->commit_wait);
2427
2428         spin_lock(&fs_info->trans_lock);
2429         list_del_init(&cur_trans->list);
2430         spin_unlock(&fs_info->trans_lock);
2431
2432         btrfs_put_transaction(cur_trans);
2433         btrfs_put_transaction(cur_trans);
2434
2435         if (trans->type & __TRANS_FREEZABLE)
2436                 sb_end_intwrite(fs_info->sb);
2437
2438         trace_btrfs_transaction_commit(trans->root);
2439
2440         btrfs_scrub_continue(fs_info);
2441
2442         if (current->journal_info == trans)
2443                 current->journal_info = NULL;
2444
2445         kmem_cache_free(btrfs_trans_handle_cachep, trans);
2446
2447         return ret;
2448
2449 unlock_tree_log:
2450         mutex_unlock(&fs_info->tree_log_mutex);
2451 unlock_reloc:
2452         mutex_unlock(&fs_info->reloc_mutex);
2453 scrub_continue:
2454         btrfs_scrub_continue(fs_info);
2455 cleanup_transaction:
2456         btrfs_trans_release_metadata(trans);
2457         btrfs_cleanup_pending_block_groups(trans);
2458         btrfs_trans_release_chunk_metadata(trans);
2459         trans->block_rsv = NULL;
2460         btrfs_warn(fs_info, "Skipping commit of aborted transaction.");
2461         if (current->journal_info == trans)
2462                 current->journal_info = NULL;
2463         cleanup_transaction(trans, ret);
2464
2465         return ret;
2466 }
2467
2468 /*
2469  * return < 0 if error
2470  * 0 if there are no more dead_roots at the time of call
2471  * 1 there are more to be processed, call me again
2472  *
2473  * The return value indicates there are certainly more snapshots to delete, but
2474  * if there comes a new one during processing, it may return 0. We don't mind,
2475  * because btrfs_commit_super will poke cleaner thread and it will process it a
2476  * few seconds later.
2477  */
2478 int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root)
2479 {
2480         int ret;
2481         struct btrfs_fs_info *fs_info = root->fs_info;
2482
2483         spin_lock(&fs_info->trans_lock);
2484         if (list_empty(&fs_info->dead_roots)) {
2485                 spin_unlock(&fs_info->trans_lock);
2486                 return 0;
2487         }
2488         root = list_first_entry(&fs_info->dead_roots,
2489                         struct btrfs_root, root_list);
2490         list_del_init(&root->root_list);
2491         spin_unlock(&fs_info->trans_lock);
2492
2493         btrfs_debug(fs_info, "cleaner removing %llu", root->root_key.objectid);
2494
2495         btrfs_kill_all_delayed_nodes(root);
2496         if (root->ino_cache_inode) {
2497                 iput(root->ino_cache_inode);
2498                 root->ino_cache_inode = NULL;
2499         }
2500
2501         if (btrfs_header_backref_rev(root->node) <
2502                         BTRFS_MIXED_BACKREF_REV)
2503                 ret = btrfs_drop_snapshot(root, 0, 0);
2504         else
2505                 ret = btrfs_drop_snapshot(root, 1, 0);
2506
2507         btrfs_put_root(root);
2508         return (ret < 0) ? 0 : 1;
2509 }
2510
2511 void btrfs_apply_pending_changes(struct btrfs_fs_info *fs_info)
2512 {
2513         unsigned long prev;
2514         unsigned long bit;
2515
2516         prev = xchg(&fs_info->pending_changes, 0);
2517         if (!prev)
2518                 return;
2519
2520         bit = 1 << BTRFS_PENDING_SET_INODE_MAP_CACHE;
2521         if (prev & bit)
2522                 btrfs_set_opt(fs_info->mount_opt, INODE_MAP_CACHE);
2523         prev &= ~bit;
2524
2525         bit = 1 << BTRFS_PENDING_CLEAR_INODE_MAP_CACHE;
2526         if (prev & bit)
2527                 btrfs_clear_opt(fs_info->mount_opt, INODE_MAP_CACHE);
2528         prev &= ~bit;
2529
2530         bit = 1 << BTRFS_PENDING_COMMIT;
2531         if (prev & bit)
2532                 btrfs_debug(fs_info, "pending commit done");
2533         prev &= ~bit;
2534
2535         if (prev)
2536                 btrfs_warn(fs_info,
2537                         "unknown pending changes left 0x%lx, ignoring", prev);
2538 }