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