Pileus Git - ~andy/linux/blob - fs/btrfs/transaction.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/slab.h>
  21 #include <linux/sched.h>
  22 #include <linux/writeback.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/blkdev.h>
  25 #include <linux/uuid.h>
  26 #include "ctree.h"
  27 #include "disk-io.h"
  28 #include "transaction.h"
  29 #include "locking.h"
  30 #include "tree-log.h"
  31 #include "inode-map.h"
  32 #include "volumes.h"
  33 #include "dev-replace.h"
  34
  35 #define BTRFS_ROOT_TRANS_TAG 0
  36
  37 static unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {
  38         [TRANS_STATE_RUNNING]           = 0U,
  39         [TRANS_STATE_BLOCKED]           = (__TRANS_USERSPACE |
  40                                            __TRANS_START),
  41         [TRANS_STATE_COMMIT_START]      = (__TRANS_USERSPACE |
  42                                            __TRANS_START |
  43                                            __TRANS_ATTACH),
  44         [TRANS_STATE_COMMIT_DOING]      = (__TRANS_USERSPACE |
  45                                            __TRANS_START |
  46                                            __TRANS_ATTACH |
  47                                            __TRANS_JOIN),
  48         [TRANS_STATE_UNBLOCKED]         = (__TRANS_USERSPACE |
  49                                            __TRANS_START |
  50                                            __TRANS_ATTACH |
  51                                            __TRANS_JOIN |
  52                                            __TRANS_JOIN_NOLOCK),
  53         [TRANS_STATE_COMPLETED]         = (__TRANS_USERSPACE |
  54                                            __TRANS_START |
  55                                            __TRANS_ATTACH |
  56                                            __TRANS_JOIN |
  57                                            __TRANS_JOIN_NOLOCK),
  58 };
  59
  60 void btrfs_put_transaction(struct btrfs_transaction *transaction)
  61 {
  62         WARN_ON(atomic_read(&transaction->use_count) == 0);
  63         if (atomic_dec_and_test(&transaction->use_count)) {
  64                 BUG_ON(!list_empty(&transaction->list));
  65                 WARN_ON(!RB_EMPTY_ROOT(&transaction->delayed_refs.root));
  66                 WARN_ON(!RB_EMPTY_ROOT(&transaction->delayed_refs.href_root));
  67                 while (!list_empty(&transaction->pending_chunks)) {
  68                         struct extent_map *em;
  69
  70                         em = list_first_entry(&transaction->pending_chunks,
  71                                               struct extent_map, list);
  72                         list_del_init(&em->list);
  73                         free_extent_map(em);
  74                 }
  75                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  76         }
  77 }
  78
  79 static noinline void switch_commit_root(struct btrfs_root *root)
  80 {
  81         free_extent_buffer(root->commit_root);
  82         root->commit_root = btrfs_root_node(root);
  83 }
  84
  85 static inline void extwriter_counter_inc(struct btrfs_transaction *trans,
  86                                          unsigned int type)
  87 {
  88         if (type & TRANS_EXTWRITERS)
  89                 atomic_inc(&trans->num_extwriters);
  90 }
  91
  92 static inline void extwriter_counter_dec(struct btrfs_transaction *trans,
  93                                          unsigned int type)
  94 {
  95         if (type & TRANS_EXTWRITERS)
  96                 atomic_dec(&trans->num_extwriters);
  97 }
  98
  99 static inline void extwriter_counter_init(struct btrfs_transaction *trans,
 100                                           unsigned int type)
 101 {
 102         atomic_set(&trans->num_extwriters, ((type & TRANS_EXTWRITERS) ? 1 : 0));
 103 }
 104
 105 static inline int extwriter_counter_read(struct btrfs_transaction *trans)
 106 {
 107         return atomic_read(&trans->num_extwriters);
 108 }
 109
 110 /*
 111  * either allocate a new transaction or hop into the existing one
 112  */
 113 static noinline int join_transaction(struct btrfs_root *root, unsigned int type)
 114 {
 115         struct btrfs_transaction *cur_trans;
 116         struct btrfs_fs_info *fs_info = root->fs_info;
 117
 118         spin_lock(&fs_info->trans_lock);
 119 loop:
 120         /* The file system has been taken offline. No new transactions. */
 121         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 122                 spin_unlock(&fs_info->trans_lock);
 123                 return -EROFS;
 124         }
 125
 126         cur_trans = fs_info->running_transaction;
 127         if (cur_trans) {
 128                 if (cur_trans->aborted) {
 129                         spin_unlock(&fs_info->trans_lock);
 130                         return cur_trans->aborted;
 131                 }
 132                 if (btrfs_blocked_trans_types[cur_trans->state] & type) {
 133                         spin_unlock(&fs_info->trans_lock);
 134                         return -EBUSY;
 135                 }
 136                 atomic_inc(&cur_trans->use_count);
 137                 atomic_inc(&cur_trans->num_writers);
 138                 extwriter_counter_inc(cur_trans, type);
 139                 spin_unlock(&fs_info->trans_lock);
 140                 return 0;
 141         }
 142         spin_unlock(&fs_info->trans_lock);
 143
 144         /*
 145          * If we are ATTACH, we just want to catch the current transaction,
 146          * and commit it. If there is no transaction, just return ENOENT.
 147          */
 148         if (type == TRANS_ATTACH)
 149                 return -ENOENT;
 150
 151         /*
 152          * JOIN_NOLOCK only happens during the transaction commit, so
 153          * it is impossible that ->running_transaction is NULL
 154          */
 155         BUG_ON(type == TRANS_JOIN_NOLOCK);
 156
 157         cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
 158         if (!cur_trans)
 159                 return -ENOMEM;
 160
 161         spin_lock(&fs_info->trans_lock);
 162         if (fs_info->running_transaction) {
 163                 /*
 164                  * someone started a transaction after we unlocked.  Make sure
 165                  * to redo the checks above
 166                  */
 167                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 168                 goto loop;
 169         } else if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 170                 spin_unlock(&fs_info->trans_lock);
 171                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 172                 return -EROFS;
 173         }
 174
 175         atomic_set(&cur_trans->num_writers, 1);
 176         extwriter_counter_init(cur_trans, type);
 177         init_waitqueue_head(&cur_trans->writer_wait);
 178         init_waitqueue_head(&cur_trans->commit_wait);
 179         cur_trans->state = TRANS_STATE_RUNNING;
 180         /*
 181          * One for this trans handle, one so it will live on until we
 182          * commit the transaction.
 183          */
 184         atomic_set(&cur_trans->use_count, 2);
 185         cur_trans->start_time = get_seconds();
 186
 187         cur_trans->delayed_refs.root = RB_ROOT;
 188         cur_trans->delayed_refs.href_root = RB_ROOT;
 189         cur_trans->delayed_refs.num_entries = 0;
 190         cur_trans->delayed_refs.num_heads_ready = 0;
 191         cur_trans->delayed_refs.num_heads = 0;
 192         cur_trans->delayed_refs.flushing = 0;
 193         cur_trans->delayed_refs.run_delayed_start = 0;
 194
 195         /*
 196          * although the tree mod log is per file system and not per transaction,
 197          * the log must never go across transaction boundaries.
 198          */
 199         smp_mb();
 200         if (!list_empty(&fs_info->tree_mod_seq_list))
 201                 WARN(1, KERN_ERR "btrfs: tree_mod_seq_list not empty when "
 202                         "creating a fresh transaction\n");
 203         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log))
 204                 WARN(1, KERN_ERR "btrfs: tree_mod_log rb tree not empty when "
 205                         "creating a fresh transaction\n");
 206         atomic64_set(&fs_info->tree_mod_seq, 0);
 207
 208         spin_lock_init(&cur_trans->delayed_refs.lock);
 209         atomic_set(&cur_trans->delayed_refs.procs_running_refs, 0);
 210         atomic_set(&cur_trans->delayed_refs.ref_seq, 0);
 211         init_waitqueue_head(&cur_trans->delayed_refs.wait);
 212
 213         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 214         INIT_LIST_HEAD(&cur_trans->ordered_operations);
 215         INIT_LIST_HEAD(&cur_trans->pending_chunks);
 216         list_add_tail(&cur_trans->list, &fs_info->trans_list);
 217         extent_io_tree_init(&cur_trans->dirty_pages,
 218                              fs_info->btree_inode->i_mapping);
 219         fs_info->generation++;
 220         cur_trans->transid = fs_info->generation;
 221         fs_info->running_transaction = cur_trans;
 222         cur_trans->aborted = 0;
 223         spin_unlock(&fs_info->trans_lock);
 224
 225         return 0;
 226 }
 227
 228 /*
 229  * this does all the record keeping required to make sure that a reference
 230  * counted root is properly recorded in a given transaction.  This is required
 231  * to make sure the old root from before we joined the transaction is deleted
 232  * when the transaction commits
 233  */
 234 static int record_root_in_trans(struct btrfs_trans_handle *trans,
 235                                struct btrfs_root *root)
 236 {
 237         if (root->ref_cows && root->last_trans < trans->transid) {
 238                 WARN_ON(root == root->fs_info->extent_root);
 239                 WARN_ON(root->commit_root != root->node);
 240
 241                 /*
 242                  * see below for in_trans_setup usage rules
 243                  * we have the reloc mutex held now, so there
 244                  * is only one writer in this function
 245                  */
 246                 root->in_trans_setup = 1;
 247
 248                 /* make sure readers find in_trans_setup before
 249                  * they find our root->last_trans update
 250                  */
 251                 smp_wmb();
 252
 253                 spin_lock(&root->fs_info->fs_roots_radix_lock);
 254                 if (root->last_trans == trans->transid) {
 255                         spin_unlock(&root->fs_info->fs_roots_radix_lock);
 256                         return 0;
 257                 }
 258                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 259                            (unsigned long)root->root_key.objectid,
 260                            BTRFS_ROOT_TRANS_TAG);
 261                 spin_unlock(&root->fs_info->fs_roots_radix_lock);
 262                 root->last_trans = trans->transid;
 263
 264                 /* this is pretty tricky.  We don't want to
 265                  * take the relocation lock in btrfs_record_root_in_trans
 266                  * unless we're really doing the first setup for this root in
 267                  * this transaction.
 268                  *
 269                  * Normally we'd use root->last_trans as a flag to decide
 270                  * if we want to take the expensive mutex.
 271                  *
 272                  * But, we have to set root->last_trans before we
 273                  * init the relocation root, otherwise, we trip over warnings
 274                  * in ctree.c.  The solution used here is to flag ourselves
 275                  * with root->in_trans_setup.  When this is 1, we're still
 276                  * fixing up the reloc trees and everyone must wait.
 277                  *
 278                  * When this is zero, they can trust root->last_trans and fly
 279                  * through btrfs_record_root_in_trans without having to take the
 280                  * lock.  smp_wmb() makes sure that all the writes above are
 281                  * done before we pop in the zero below
 282                  */
 283                 btrfs_init_reloc_root(trans, root);
 284                 smp_wmb();
 285                 root->in_trans_setup = 0;
 286         }
 287         return 0;
 288 }
 289
 290
 291 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 292                                struct btrfs_root *root)
 293 {
 294         if (!root->ref_cows)
 295                 return 0;
 296
 297         /*
 298          * see record_root_in_trans for comments about in_trans_setup usage
 299          * and barriers
 300          */
 301         smp_rmb();
 302         if (root->last_trans == trans->transid &&
 303             !root->in_trans_setup)
 304                 return 0;
 305
 306         mutex_lock(&root->fs_info->reloc_mutex);
 307         record_root_in_trans(trans, root);
 308         mutex_unlock(&root->fs_info->reloc_mutex);
 309
 310         return 0;
 311 }
 312
 313 static inline int is_transaction_blocked(struct btrfs_transaction *trans)
 314 {
 315         return (trans->state >= TRANS_STATE_BLOCKED &&
 316                 trans->state < TRANS_STATE_UNBLOCKED &&
 317                 !trans->aborted);
 318 }
 319
 320 /* wait for commit against the current transaction to become unblocked
 321  * when this is done, it is safe to start a new transaction, but the current
 322  * transaction might not be fully on disk.
 323  */
 324 static void wait_current_trans(struct btrfs_root *root)
 325 {
 326         struct btrfs_transaction *cur_trans;
 327
 328         spin_lock(&root->fs_info->trans_lock);
 329         cur_trans = root->fs_info->running_transaction;
 330         if (cur_trans && is_transaction_blocked(cur_trans)) {
 331                 atomic_inc(&cur_trans->use_count);
 332                 spin_unlock(&root->fs_info->trans_lock);
 333
 334                 wait_event(root->fs_info->transaction_wait,
 335                            cur_trans->state >= TRANS_STATE_UNBLOCKED ||
 336                            cur_trans->aborted);
 337                 btrfs_put_transaction(cur_trans);
 338         } else {
 339                 spin_unlock(&root->fs_info->trans_lock);
 340         }
 341 }
 342
 343 static int may_wait_transaction(struct btrfs_root *root, int type)
 344 {
 345         if (root->fs_info->log_root_recovering)
 346                 return 0;
 347
 348         if (type == TRANS_USERSPACE)
 349                 return 1;
 350
 351         if (type == TRANS_START &&
 352             !atomic_read(&root->fs_info->open_ioctl_trans))
 353                 return 1;
 354
 355         return 0;
 356 }
 357
 358 static inline bool need_reserve_reloc_root(struct btrfs_root *root)
 359 {
 360         if (!root->fs_info->reloc_ctl ||
 361             !root->ref_cows ||
 362             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 363             root->reloc_root)
 364                 return false;
 365
 366         return true;
 367 }
 368
 369 static struct btrfs_trans_handle *
 370 start_transaction(struct btrfs_root *root, u64 num_items, unsigned int type,
 371                   enum btrfs_reserve_flush_enum flush)
 372 {
 373         struct btrfs_trans_handle *h;
 374         struct btrfs_transaction *cur_trans;
 375         u64 num_bytes = 0;
 376         u64 qgroup_reserved = 0;
 377         bool reloc_reserved = false;
 378         int ret;
 379
 380         if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state))
 381                 return ERR_PTR(-EROFS);
 382
 383         if (current->journal_info) {
 384                 WARN_ON(type & TRANS_EXTWRITERS);
 385                 h = current->journal_info;
 386                 h->use_count++;
 387                 WARN_ON(h->use_count > 2);
 388                 h->orig_rsv = h->block_rsv;
 389                 h->block_rsv = NULL;
 390                 goto got_it;
 391         }
 392
 393         /*
 394          * Do the reservation before we join the transaction so we can do all
 395          * the appropriate flushing if need be.
 396          */
 397         if (num_items > 0 && root != root->fs_info->chunk_root) {
 398                 if (root->fs_info->quota_enabled &&
 399                     is_fstree(root->root_key.objectid)) {
 400                         qgroup_reserved = num_items * root->leafsize;
 401                         ret = btrfs_qgroup_reserve(root, qgroup_reserved);
 402                         if (ret)
 403                                 return ERR_PTR(ret);
 404                 }
 405
 406                 num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
 407                 /*
 408                  * Do the reservation for the relocation root creation
 409                  */
 410                 if (unlikely(need_reserve_reloc_root(root))) {
 411                         num_bytes += root->nodesize;
 412                         reloc_reserved = true;
 413                 }
 414
 415                 ret = btrfs_block_rsv_add(root,
 416                                           &root->fs_info->trans_block_rsv,
 417                                           num_bytes, flush);
 418                 if (ret)
 419                         goto reserve_fail;
 420         }
 421 again:
 422         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 423         if (!h) {
 424                 ret = -ENOMEM;
 425                 goto alloc_fail;
 426         }
 427
 428         /*
 429          * If we are JOIN_NOLOCK we're already committing a transaction and
 430          * waiting on this guy, so we don't need to do the sb_start_intwrite
 431          * because we're already holding a ref.  We need this because we could
 432          * have raced in and did an fsync() on a file which can kick a commit
 433          * and then we deadlock with somebody doing a freeze.
 434          *
 435          * If we are ATTACH, it means we just want to catch the current
 436          * transaction and commit it, so we needn't do sb_start_intwrite().
 437          */
 438         if (type & __TRANS_FREEZABLE)
 439                 sb_start_intwrite(root->fs_info->sb);
 440
 441         if (may_wait_transaction(root, type))
 442                 wait_current_trans(root);
 443
 444         do {
 445                 ret = join_transaction(root, type);
 446                 if (ret == -EBUSY) {
 447                         wait_current_trans(root);
 448                         if (unlikely(type == TRANS_ATTACH))
 449                                 ret = -ENOENT;
 450                 }
 451         } while (ret == -EBUSY);
 452
 453         if (ret < 0) {
 454                 /* We must get the transaction if we are JOIN_NOLOCK. */
 455                 BUG_ON(type == TRANS_JOIN_NOLOCK);
 456                 goto join_fail;
 457         }
 458
 459         cur_trans = root->fs_info->running_transaction;
 460
 461         h->transid = cur_trans->transid;
 462         h->transaction = cur_trans;
 463         h->blocks_used = 0;
 464         h->bytes_reserved = 0;
 465         h->root = root;
 466         h->delayed_ref_updates = 0;
 467         h->use_count = 1;
 468         h->adding_csums = 0;
 469         h->block_rsv = NULL;
 470         h->orig_rsv = NULL;
 471         h->aborted = 0;
 472         h->qgroup_reserved = 0;
 473         h->delayed_ref_elem.seq = 0;
 474         h->type = type;
 475         h->allocating_chunk = false;
 476         h->reloc_reserved = false;
 477         INIT_LIST_HEAD(&h->qgroup_ref_list);
 478         INIT_LIST_HEAD(&h->new_bgs);
 479
 480         smp_mb();
 481         if (cur_trans->state >= TRANS_STATE_BLOCKED &&
 482             may_wait_transaction(root, type)) {
 483                 btrfs_commit_transaction(h, root);
 484                 goto again;
 485         }
 486
 487         if (num_bytes) {
 488                 trace_btrfs_space_reservation(root->fs_info, "transaction",
 489                                               h->transid, num_bytes, 1);
 490                 h->block_rsv = &root->fs_info->trans_block_rsv;
 491                 h->bytes_reserved = num_bytes;
 492                 h->reloc_reserved = reloc_reserved;
 493         }
 494         h->qgroup_reserved = qgroup_reserved;
 495
 496 got_it:
 497         btrfs_record_root_in_trans(h, root);
 498
 499         if (!current->journal_info && type != TRANS_USERSPACE)
 500                 current->journal_info = h;
 501         return h;
 502
 503 join_fail:
 504         if (type & __TRANS_FREEZABLE)
 505                 sb_end_intwrite(root->fs_info->sb);
 506         kmem_cache_free(btrfs_trans_handle_cachep, h);
 507 alloc_fail:
 508         if (num_bytes)
 509                 btrfs_block_rsv_release(root, &root->fs_info->trans_block_rsv,
 510                                         num_bytes);
 511 reserve_fail:
 512         if (qgroup_reserved)
 513                 btrfs_qgroup_free(root, qgroup_reserved);
 514         return ERR_PTR(ret);
 515 }
 516
 517 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 518                                                    int num_items)
 519 {
 520         return start_transaction(root, num_items, TRANS_START,
 521                                  BTRFS_RESERVE_FLUSH_ALL);
 522 }
 523
 524 struct btrfs_trans_handle *btrfs_start_transaction_lflush(
 525                                         struct btrfs_root *root, int num_items)
 526 {
 527         return start_transaction(root, num_items, TRANS_START,
 528                                  BTRFS_RESERVE_FLUSH_LIMIT);
 529 }
 530
 531 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 532 {
 533         return start_transaction(root, 0, TRANS_JOIN, 0);
 534 }
 535
 536 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
 537 {
 538         return start_transaction(root, 0, TRANS_JOIN_NOLOCK, 0);
 539 }
 540
 541 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 542 {
 543         return start_transaction(root, 0, TRANS_USERSPACE, 0);
 544 }
 545
 546 /*
 547  * btrfs_attach_transaction() - catch the running transaction
 548  *
 549  * It is used when we want to commit the current the transaction, but
 550  * don't want to start a new one.
 551  *
 552  * Note: If this function return -ENOENT, it just means there is no
 553  * running transaction. But it is possible that the inactive transaction
 554  * is still in the memory, not fully on disk. If you hope there is no
 555  * inactive transaction in the fs when -ENOENT is returned, you should
 556  * invoke
 557  *     btrfs_attach_transaction_barrier()
 558  */
 559 struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
 560 {
 561         return start_transaction(root, 0, TRANS_ATTACH, 0);
 562 }
 563
 564 /*
 565  * btrfs_attach_transaction_barrier() - catch the running transaction
 566  *
 567  * It is similar to the above function, the differentia is this one
 568  * will wait for all the inactive transactions until they fully
 569  * complete.
 570  */
 571 struct btrfs_trans_handle *
 572 btrfs_attach_transaction_barrier(struct btrfs_root *root)
 573 {
 574         struct btrfs_trans_handle *trans;
 575
 576         trans = start_transaction(root, 0, TRANS_ATTACH, 0);
 577         if (IS_ERR(trans) && PTR_ERR(trans) == -ENOENT)
 578                 btrfs_wait_for_commit(root, 0);
 579
 580         return trans;
 581 }
 582
 583 /* wait for a transaction commit to be fully complete */
 584 static noinline void wait_for_commit(struct btrfs_root *root,
 585                                     struct btrfs_transaction *commit)
 586 {
 587         wait_event(commit->commit_wait, commit->state == TRANS_STATE_COMPLETED);
 588 }
 589
 590 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 591 {
 592         struct btrfs_transaction *cur_trans = NULL, *t;
 593         int ret = 0;
 594
 595         if (transid) {
 596                 if (transid <= root->fs_info->last_trans_committed)
 597                         goto out;
 598
 599                 ret = -EINVAL;
 600                 /* find specified transaction */
 601                 spin_lock(&root->fs_info->trans_lock);
 602                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 603                         if (t->transid == transid) {
 604                                 cur_trans = t;
 605                                 atomic_inc(&cur_trans->use_count);
 606                                 ret = 0;
 607                                 break;
 608                         }
 609                         if (t->transid > transid) {
 610                                 ret = 0;
 611                                 break;
 612                         }
 613                 }
 614                 spin_unlock(&root->fs_info->trans_lock);
 615                 /* The specified transaction doesn't exist */
 616                 if (!cur_trans)
 617                         goto out;
 618         } else {
 619                 /* find newest transaction that is committing | committed */
 620                 spin_lock(&root->fs_info->trans_lock);
 621                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 622                                             list) {
 623                         if (t->state >= TRANS_STATE_COMMIT_START) {
 624                                 if (t->state == TRANS_STATE_COMPLETED)
 625                                         break;
 626                                 cur_trans = t;
 627                                 atomic_inc(&cur_trans->use_count);
 628                                 break;
 629                         }
 630                 }
 631                 spin_unlock(&root->fs_info->trans_lock);
 632                 if (!cur_trans)
 633                         goto out;  /* nothing committing|committed */
 634         }
 635
 636         wait_for_commit(root, cur_trans);
 637         btrfs_put_transaction(cur_trans);
 638 out:
 639         return ret;
 640 }
 641
 642 void btrfs_throttle(struct btrfs_root *root)
 643 {
 644         if (!atomic_read(&root->fs_info->open_ioctl_trans))
 645                 wait_current_trans(root);
 646 }
 647
 648 static int should_end_transaction(struct btrfs_trans_handle *trans,
 649                                   struct btrfs_root *root)
 650 {
 651         if (root->fs_info->global_block_rsv.space_info->full &&
 652             btrfs_should_throttle_delayed_refs(trans, root))
 653                 return 1;
 654
 655         return !!btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
 656 }
 657
 658 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 659                                  struct btrfs_root *root)
 660 {
 661         struct btrfs_transaction *cur_trans = trans->transaction;
 662         int updates;
 663         int err;
 664
 665         smp_mb();
 666         if (cur_trans->state >= TRANS_STATE_BLOCKED ||
 667             cur_trans->delayed_refs.flushing)
 668                 return 1;
 669
 670         updates = trans->delayed_ref_updates;
 671         trans->delayed_ref_updates = 0;
 672         if (updates) {
 673                 err = btrfs_run_delayed_refs(trans, root, updates);
 674                 if (err) /* Error code will also eval true */
 675                         return err;
 676         }
 677
 678         return should_end_transaction(trans, root);
 679 }
 680
 681 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 682                           struct btrfs_root *root, int throttle)
 683 {
 684         struct btrfs_transaction *cur_trans = trans->transaction;
 685         struct btrfs_fs_info *info = root->fs_info;
 686         unsigned long cur = trans->delayed_ref_updates;
 687         int lock = (trans->type != TRANS_JOIN_NOLOCK);
 688         int err = 0;
 689
 690         if (--trans->use_count) {
 691                 trans->block_rsv = trans->orig_rsv;
 692                 return 0;
 693         }
 694
 695         /*
 696          * do the qgroup accounting as early as possible
 697          */
 698         err = btrfs_delayed_refs_qgroup_accounting(trans, info);
 699
 700         btrfs_trans_release_metadata(trans, root);
 701         trans->block_rsv = NULL;
 702
 703         if (trans->qgroup_reserved) {
 704                 /*
 705                  * the same root has to be passed here between start_transaction
 706                  * and end_transaction. Subvolume quota depends on this.
 707                  */
 708                 btrfs_qgroup_free(trans->root, trans->qgroup_reserved);
 709                 trans->qgroup_reserved = 0;
 710         }
 711
 712         if (!list_empty(&trans->new_bgs))
 713                 btrfs_create_pending_block_groups(trans, root);
 714
 715         trans->delayed_ref_updates = 0;
 716         if (btrfs_should_throttle_delayed_refs(trans, root)) {
 717                 cur = max_t(unsigned long, cur, 1);
 718                 trans->delayed_ref_updates = 0;
 719                 btrfs_run_delayed_refs(trans, root, cur);
 720         }
 721
 722         btrfs_trans_release_metadata(trans, root);
 723         trans->block_rsv = NULL;
 724
 725         if (!list_empty(&trans->new_bgs))
 726                 btrfs_create_pending_block_groups(trans, root);
 727
 728         if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
 729             should_end_transaction(trans, root) &&
 730             ACCESS_ONCE(cur_trans->state) == TRANS_STATE_RUNNING) {
 731                 spin_lock(&info->trans_lock);
 732                 if (cur_trans->state == TRANS_STATE_RUNNING)
 733                         cur_trans->state = TRANS_STATE_BLOCKED;
 734                 spin_unlock(&info->trans_lock);
 735         }
 736
 737         if (lock && ACCESS_ONCE(cur_trans->state) == TRANS_STATE_BLOCKED) {
 738                 if (throttle) {
 739                         /*
 740                          * We may race with somebody else here so end up having
 741                          * to call end_transaction on ourselves again, so inc
 742                          * our use_count.
 743                          */
 744                         trans->use_count++;
 745                         return btrfs_commit_transaction(trans, root);
 746                 } else {
 747                         wake_up_process(info->transaction_kthread);
 748                 }
 749         }
 750
 751         if (trans->type & __TRANS_FREEZABLE)
 752                 sb_end_intwrite(root->fs_info->sb);
 753
 754         WARN_ON(cur_trans != info->running_transaction);
 755         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 756         atomic_dec(&cur_trans->num_writers);
 757         extwriter_counter_dec(cur_trans, trans->type);
 758
 759         smp_mb();
 760         if (waitqueue_active(&cur_trans->writer_wait))
 761                 wake_up(&cur_trans->writer_wait);
 762         btrfs_put_transaction(cur_trans);
 763
 764         if (current->journal_info == trans)
 765                 current->journal_info = NULL;
 766
 767         if (throttle)
 768                 btrfs_run_delayed_iputs(root);
 769
 770         if (trans->aborted ||
 771             test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) {
 772                 wake_up_process(info->transaction_kthread);
 773                 err = -EIO;
 774         }
 775         assert_qgroups_uptodate(trans);
 776
 777         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 778         return err;
 779 }
 780
 781 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 782                           struct btrfs_root *root)
 783 {
 784         return __btrfs_end_transaction(trans, root, 0);
 785 }
 786
 787 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 788                                    struct btrfs_root *root)
 789 {
 790         return __btrfs_end_transaction(trans, root, 1);
 791 }
 792
 793 int btrfs_end_transaction_dmeta(struct btrfs_trans_handle *trans,
 794                                 struct btrfs_root *root)
 795 {
 796         return __btrfs_end_transaction(trans, root, 1);
 797 }
 798
 799 /*
 800  * when btree blocks are allocated, they have some corresponding bits set for
 801  * them in one of two extent_io trees.  This is used to make sure all of
 802  * those extents are sent to disk but does not wait on them
 803  */
 804 int btrfs_write_marked_extents(struct btrfs_root *root,
 805                                struct extent_io_tree *dirty_pages, int mark)
 806 {
 807         int err = 0;
 808         int werr = 0;
 809         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 810         struct extent_state *cached_state = NULL;
 811         u64 start = 0;
 812         u64 end;
 813
 814         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 815                                       mark, &cached_state)) {
 816                 convert_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT,
 817                                    mark, &cached_state, GFP_NOFS);
 818                 cached_state = NULL;
 819                 err = filemap_fdatawrite_range(mapping, start, end);
 820                 if (err)
 821                         werr = err;
 822                 cond_resched();
 823                 start = end + 1;
 824         }
 825         if (err)
 826                 werr = err;
 827         return werr;
 828 }
 829
 830 /*
 831  * when btree blocks are allocated, they have some corresponding bits set for
 832  * them in one of two extent_io trees.  This is used to make sure all of
 833  * those extents are on disk for transaction or log commit.  We wait
 834  * on all the pages and clear them from the dirty pages state tree
 835  */
 836 int btrfs_wait_marked_extents(struct btrfs_root *root,
 837                               struct extent_io_tree *dirty_pages, int mark)
 838 {
 839         int err = 0;
 840         int werr = 0;
 841         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 842         struct extent_state *cached_state = NULL;
 843         u64 start = 0;
 844         u64 end;
 845
 846         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 847                                       EXTENT_NEED_WAIT, &cached_state)) {
 848                 clear_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT,
 849                                  0, 0, &cached_state, GFP_NOFS);
 850                 err = filemap_fdatawait_range(mapping, start, end);
 851                 if (err)
 852                         werr = err;
 853                 cond_resched();
 854                 start = end + 1;
 855         }
 856         if (err)
 857                 werr = err;
 858         return werr;
 859 }
 860
 861 /*
 862  * when btree blocks are allocated, they have some corresponding bits set for
 863  * them in one of two extent_io trees.  This is used to make sure all of
 864  * those extents are on disk for transaction or log commit
 865  */
 866 static int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 867                                 struct extent_io_tree *dirty_pages, int mark)
 868 {
 869         int ret;
 870         int ret2;
 871         struct blk_plug plug;
 872
 873         blk_start_plug(&plug);
 874         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 875         blk_finish_plug(&plug);
 876         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 877
 878         if (ret)
 879                 return ret;
 880         if (ret2)
 881                 return ret2;
 882         return 0;
 883 }
 884
 885 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 886                                      struct btrfs_root *root)
 887 {
 888         if (!trans || !trans->transaction) {
 889                 struct inode *btree_inode;
 890                 btree_inode = root->fs_info->btree_inode;
 891                 return filemap_write_and_wait(btree_inode->i_mapping);
 892         }
 893         return btrfs_write_and_wait_marked_extents(root,
 894                                            &trans->transaction->dirty_pages,
 895                                            EXTENT_DIRTY);
 896 }
 897
 898 /*
 899  * this is used to update the root pointer in the tree of tree roots.
 900  *
 901  * But, in the case of the extent allocation tree, updating the root
 902  * pointer may allocate blocks which may change the root of the extent
 903  * allocation tree.
 904  *
 905  * So, this loops and repeats and makes sure the cowonly root didn't
 906  * change while the root pointer was being updated in the metadata.
 907  */
 908 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 909                                struct btrfs_root *root)
 910 {
 911         int ret;
 912         u64 old_root_bytenr;
 913         u64 old_root_used;
 914         struct btrfs_root *tree_root = root->fs_info->tree_root;
 915
 916         old_root_used = btrfs_root_used(&root->root_item);
 917         btrfs_write_dirty_block_groups(trans, root);
 918
 919         while (1) {
 920                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 921                 if (old_root_bytenr == root->node->start &&
 922                     old_root_used == btrfs_root_used(&root->root_item))
 923                         break;
 924
 925                 btrfs_set_root_node(&root->root_item, root->node);
 926                 ret = btrfs_update_root(trans, tree_root,
 927                                         &root->root_key,
 928                                         &root->root_item);
 929                 if (ret)
 930                         return ret;
 931
 932                 old_root_used = btrfs_root_used(&root->root_item);
 933                 ret = btrfs_write_dirty_block_groups(trans, root);
 934                 if (ret)
 935                         return ret;
 936         }
 937
 938         if (root != root->fs_info->extent_root)
 939                 switch_commit_root(root);
 940
 941         return 0;
 942 }
 943
 944 /*
 945  * update all the cowonly tree roots on disk
 946  *
 947  * The error handling in this function may not be obvious. Any of the
 948  * failures will cause the file system to go offline. We still need
 949  * to clean up the delayed refs.
 950  */
 951 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 952                                          struct btrfs_root *root)
 953 {
 954         struct btrfs_fs_info *fs_info = root->fs_info;
 955         struct list_head *next;
 956         struct extent_buffer *eb;
 957         int ret;
 958
 959         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 960         if (ret)
 961                 return ret;
 962
 963         eb = btrfs_lock_root_node(fs_info->tree_root);
 964         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
 965                               0, &eb);
 966         btrfs_tree_unlock(eb);
 967         free_extent_buffer(eb);
 968
 969         if (ret)
 970                 return ret;
 971
 972         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 973         if (ret)
 974                 return ret;
 975
 976         ret = btrfs_run_dev_stats(trans, root->fs_info);
 977         if (ret)
 978                 return ret;
 979         ret = btrfs_run_dev_replace(trans, root->fs_info);
 980         if (ret)
 981                 return ret;
 982         ret = btrfs_run_qgroups(trans, root->fs_info);
 983         if (ret)
 984                 return ret;
 985
 986         /* run_qgroups might have added some more refs */
 987         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 988         if (ret)
 989                 return ret;
 990
 991         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 992                 next = fs_info->dirty_cowonly_roots.next;
 993                 list_del_init(next);
 994                 root = list_entry(next, struct btrfs_root, dirty_list);
 995
 996                 ret = update_cowonly_root(trans, root);
 997                 if (ret)
 998                         return ret;
 999         }
1000
1001         down_write(&fs_info->extent_commit_sem);
1002         switch_commit_root(fs_info->extent_root);
1003         up_write(&fs_info->extent_commit_sem);
1004
1005         btrfs_after_dev_replace_commit(fs_info);
1006
1007         return 0;
1008 }
1009
1010 /*
1011  * dead roots are old snapshots that need to be deleted.  This allocates
1012  * a dirty root struct and adds it into the list of dead roots that need to
1013  * be deleted
1014  */
1015 void btrfs_add_dead_root(struct btrfs_root *root)
1016 {
1017         spin_lock(&root->fs_info->trans_lock);
1018         if (list_empty(&root->root_list))
1019                 list_add_tail(&root->root_list, &root->fs_info->dead_roots);
1020         spin_unlock(&root->fs_info->trans_lock);
1021 }
1022
1023 /*
1024  * update all the cowonly tree roots on disk
1025  */
1026 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
1027                                     struct btrfs_root *root)
1028 {
1029         struct btrfs_root *gang[8];
1030         struct btrfs_fs_info *fs_info = root->fs_info;
1031         int i;
1032         int ret;
1033         int err = 0;
1034
1035         spin_lock(&fs_info->fs_roots_radix_lock);
1036         while (1) {
1037                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
1038                                                  (void **)gang, 0,
1039                                                  ARRAY_SIZE(gang),
1040                                                  BTRFS_ROOT_TRANS_TAG);
1041                 if (ret == 0)
1042                         break;
1043                 for (i = 0; i < ret; i++) {
1044                         root = gang[i];
1045                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
1046                                         (unsigned long)root->root_key.objectid,
1047                                         BTRFS_ROOT_TRANS_TAG);
1048                         spin_unlock(&fs_info->fs_roots_radix_lock);
1049
1050                         btrfs_free_log(trans, root);
1051                         btrfs_update_reloc_root(trans, root);
1052                         btrfs_orphan_commit_root(trans, root);
1053
1054                         btrfs_save_ino_cache(root, trans);
1055
1056                         /* see comments in should_cow_block() */
1057                         root->force_cow = 0;
1058                         smp_wmb();
1059
1060                         if (root->commit_root != root->node) {
1061                                 mutex_lock(&root->fs_commit_mutex);
1062                                 switch_commit_root(root);
1063                                 btrfs_unpin_free_ino(root);
1064                                 mutex_unlock(&root->fs_commit_mutex);
1065
1066                                 btrfs_set_root_node(&root->root_item,
1067                                                     root->node);
1068                         }
1069
1070                         err = btrfs_update_root(trans, fs_info->tree_root,
1071                                                 &root->root_key,
1072                                                 &root->root_item);
1073                         spin_lock(&fs_info->fs_roots_radix_lock);
1074                         if (err)
1075                                 break;
1076                 }
1077         }
1078         spin_unlock(&fs_info->fs_roots_radix_lock);
1079         return err;
1080 }
1081
1082 /*
1083  * defrag a given btree.
1084  * Every leaf in the btree is read and defragged.
1085  */
1086 int btrfs_defrag_root(struct btrfs_root *root)
1087 {
1088         struct btrfs_fs_info *info = root->fs_info;
1089         struct btrfs_trans_handle *trans;
1090         int ret;
1091
1092         if (xchg(&root->defrag_running, 1))
1093                 return 0;
1094
1095         while (1) {
1096                 trans = btrfs_start_transaction(root, 0);
1097                 if (IS_ERR(trans))
1098                         return PTR_ERR(trans);
1099
1100                 ret = btrfs_defrag_leaves(trans, root);
1101
1102                 btrfs_end_transaction(trans, root);
1103                 btrfs_btree_balance_dirty(info->tree_root);
1104                 cond_resched();
1105
1106                 if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
1107                         break;
1108
1109                 if (btrfs_defrag_cancelled(root->fs_info)) {
1110                         printk(KERN_DEBUG "btrfs: defrag_root cancelled\n");
1111                         ret = -EAGAIN;
1112                         break;
1113                 }
1114         }
1115         root->defrag_running = 0;
1116         return ret;
1117 }
1118
1119 /*
1120  * new snapshots need to be created at a very specific time in the
1121  * transaction commit.  This does the actual creation.
1122  *
1123  * Note:
1124  * If the error which may affect the commitment of the current transaction
1125  * happens, we should return the error number. If the error which just affect
1126  * the creation of the pending snapshots, just return 0.
1127  */
1128 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
1129                                    struct btrfs_fs_info *fs_info,
1130                                    struct btrfs_pending_snapshot *pending)
1131 {
1132         struct btrfs_key key;
1133         struct btrfs_root_item *new_root_item;
1134         struct btrfs_root *tree_root = fs_info->tree_root;
1135         struct btrfs_root *root = pending->root;
1136         struct btrfs_root *parent_root;
1137         struct btrfs_block_rsv *rsv;
1138         struct inode *parent_inode;
1139         struct btrfs_path *path;
1140         struct btrfs_dir_item *dir_item;
1141         struct dentry *dentry;
1142         struct extent_buffer *tmp;
1143         struct extent_buffer *old;
1144         struct timespec cur_time = CURRENT_TIME;
1145         int ret = 0;
1146         u64 to_reserve = 0;
1147         u64 index = 0;
1148         u64 objectid;
1149         u64 root_flags;
1150         uuid_le new_uuid;
1151
1152         path = btrfs_alloc_path();
1153         if (!path) {
1154                 pending->error = -ENOMEM;
1155                 return 0;
1156         }
1157
1158         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
1159         if (!new_root_item) {
1160                 pending->error = -ENOMEM;
1161                 goto root_item_alloc_fail;
1162         }
1163
1164         pending->error = btrfs_find_free_objectid(tree_root, &objectid);
1165         if (pending->error)
1166                 goto no_free_objectid;
1167
1168         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
1169
1170         if (to_reserve > 0) {
1171                 pending->error = btrfs_block_rsv_add(root,
1172                                                      &pending->block_rsv,
1173                                                      to_reserve,
1174                                                      BTRFS_RESERVE_NO_FLUSH);
1175                 if (pending->error)
1176                         goto no_free_objectid;
1177         }
1178
1179         pending->error = btrfs_qgroup_inherit(trans, fs_info,
1180                                               root->root_key.objectid,
1181                                               objectid, pending->inherit);
1182         if (pending->error)
1183                 goto no_free_objectid;
1184
1185         key.objectid = objectid;
1186         key.offset = (u64)-1;
1187         key.type = BTRFS_ROOT_ITEM_KEY;
1188
1189         rsv = trans->block_rsv;
1190         trans->block_rsv = &pending->block_rsv;
1191         trans->bytes_reserved = trans->block_rsv->reserved;
1192
1193         dentry = pending->dentry;
1194         parent_inode = pending->dir;
1195         parent_root = BTRFS_I(parent_inode)->root;
1196         record_root_in_trans(trans, parent_root);
1197
1198         /*
1199          * insert the directory item
1200          */
1201         ret = btrfs_set_inode_index(parent_inode, &index);
1202         BUG_ON(ret); /* -ENOMEM */
1203
1204         /* check if there is a file/dir which has the same name. */
1205         dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1206                                          btrfs_ino(parent_inode),
1207                                          dentry->d_name.name,
1208                                          dentry->d_name.len, 0);
1209         if (dir_item != NULL && !IS_ERR(dir_item)) {
1210                 pending->error = -EEXIST;
1211                 goto dir_item_existed;
1212         } else if (IS_ERR(dir_item)) {
1213                 ret = PTR_ERR(dir_item);
1214                 btrfs_abort_transaction(trans, root, ret);
1215                 goto fail;
1216         }
1217         btrfs_release_path(path);
1218
1219         /*
1220          * pull in the delayed directory update
1221          * and the delayed inode item
1222          * otherwise we corrupt the FS during
1223          * snapshot
1224          */
1225         ret = btrfs_run_delayed_items(trans, root);
1226         if (ret) {      /* Transaction aborted */
1227                 btrfs_abort_transaction(trans, root, ret);
1228                 goto fail;
1229         }
1230
1231         record_root_in_trans(trans, root);
1232         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1233         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1234         btrfs_check_and_init_root_item(new_root_item);
1235
1236         root_flags = btrfs_root_flags(new_root_item);
1237         if (pending->readonly)
1238                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1239         else
1240                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1241         btrfs_set_root_flags(new_root_item, root_flags);
1242
1243         btrfs_set_root_generation_v2(new_root_item,
1244                         trans->transid);
1245         uuid_le_gen(&new_uuid);
1246         memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
1247         memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1248                         BTRFS_UUID_SIZE);
1249         if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
1250                 memset(new_root_item->received_uuid, 0,
1251                        sizeof(new_root_item->received_uuid));
1252                 memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1253                 memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1254                 btrfs_set_root_stransid(new_root_item, 0);
1255                 btrfs_set_root_rtransid(new_root_item, 0);
1256         }
1257         btrfs_set_stack_timespec_sec(&new_root_item->otime, cur_time.tv_sec);
1258         btrfs_set_stack_timespec_nsec(&new_root_item->otime, cur_time.tv_nsec);
1259         btrfs_set_root_otransid(new_root_item, trans->transid);
1260
1261         old = btrfs_lock_root_node(root);
1262         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1263         if (ret) {
1264                 btrfs_tree_unlock(old);
1265                 free_extent_buffer(old);
1266                 btrfs_abort_transaction(trans, root, ret);
1267                 goto fail;
1268         }
1269
1270         btrfs_set_lock_blocking(old);
1271
1272         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1273         /* clean up in any case */
1274         btrfs_tree_unlock(old);
1275         free_extent_buffer(old);
1276         if (ret) {
1277                 btrfs_abort_transaction(trans, root, ret);
1278                 goto fail;
1279         }
1280
1281         /* see comments in should_cow_block() */
1282         root->force_cow = 1;
1283         smp_wmb();
1284
1285         btrfs_set_root_node(new_root_item, tmp);
1286         /* record when the snapshot was created in key.offset */
1287         key.offset = trans->transid;
1288         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1289         btrfs_tree_unlock(tmp);
1290         free_extent_buffer(tmp);
1291         if (ret) {
1292                 btrfs_abort_transaction(trans, root, ret);
1293                 goto fail;
1294         }
1295
1296         /*
1297          * insert root back/forward references
1298          */
1299         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1300                                  parent_root->root_key.objectid,
1301                                  btrfs_ino(parent_inode), index,
1302                                  dentry->d_name.name, dentry->d_name.len);
1303         if (ret) {
1304                 btrfs_abort_transaction(trans, root, ret);
1305                 goto fail;
1306         }
1307
1308         key.offset = (u64)-1;
1309         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1310         if (IS_ERR(pending->snap)) {
1311                 ret = PTR_ERR(pending->snap);
1312                 btrfs_abort_transaction(trans, root, ret);
1313                 goto fail;
1314         }
1315
1316         ret = btrfs_reloc_post_snapshot(trans, pending);
1317         if (ret) {
1318                 btrfs_abort_transaction(trans, root, ret);
1319                 goto fail;
1320         }
1321
1322         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1323         if (ret) {
1324                 btrfs_abort_transaction(trans, root, ret);
1325                 goto fail;
1326         }
1327
1328         ret = btrfs_insert_dir_item(trans, parent_root,
1329                                     dentry->d_name.name, dentry->d_name.len,
1330                                     parent_inode, &key,
1331                                     BTRFS_FT_DIR, index);
1332         /* We have check then name at the beginning, so it is impossible. */
1333         BUG_ON(ret == -EEXIST || ret == -EOVERFLOW);
1334         if (ret) {
1335                 btrfs_abort_transaction(trans, root, ret);
1336                 goto fail;
1337         }
1338
1339         btrfs_i_size_write(parent_inode, parent_inode->i_size +
1340                                          dentry->d_name.len * 2);
1341         parent_inode->i_mtime = parent_inode->i_ctime = CURRENT_TIME;
1342         ret = btrfs_update_inode_fallback(trans, parent_root, parent_inode);
1343         if (ret) {
1344                 btrfs_abort_transaction(trans, root, ret);
1345                 goto fail;
1346         }
1347         ret = btrfs_uuid_tree_add(trans, fs_info->uuid_root, new_uuid.b,
1348                                   BTRFS_UUID_KEY_SUBVOL, objectid);
1349         if (ret) {
1350                 btrfs_abort_transaction(trans, root, ret);
1351                 goto fail;
1352         }
1353         if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
1354                 ret = btrfs_uuid_tree_add(trans, fs_info->uuid_root,
1355                                           new_root_item->received_uuid,
1356                                           BTRFS_UUID_KEY_RECEIVED_SUBVOL,
1357                                           objectid);
1358                 if (ret && ret != -EEXIST) {
1359                         btrfs_abort_transaction(trans, root, ret);
1360                         goto fail;
1361                 }
1362         }
1363 fail:
1364         pending->error = ret;
1365 dir_item_existed:
1366         trans->block_rsv = rsv;
1367         trans->bytes_reserved = 0;
1368 no_free_objectid:
1369         kfree(new_root_item);
1370 root_item_alloc_fail:
1371         btrfs_free_path(path);
1372         return ret;
1373 }
1374
1375 /*
1376  * create all the snapshots we've scheduled for creation
1377  */
1378 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1379                                              struct btrfs_fs_info *fs_info)
1380 {
1381         struct btrfs_pending_snapshot *pending, *next;
1382         struct list_head *head = &trans->transaction->pending_snapshots;
1383         int ret = 0;
1384
1385         list_for_each_entry_safe(pending, next, head, list) {
1386                 list_del(&pending->list);
1387                 ret = create_pending_snapshot(trans, fs_info, pending);
1388                 if (ret)
1389                         break;
1390         }
1391         return ret;
1392 }
1393
1394 static void update_super_roots(struct btrfs_root *root)
1395 {
1396         struct btrfs_root_item *root_item;
1397         struct btrfs_super_block *super;
1398
1399         super = root->fs_info->super_copy;
1400
1401         root_item = &root->fs_info->chunk_root->root_item;
1402         super->chunk_root = root_item->bytenr;
1403         super->chunk_root_generation = root_item->generation;
1404         super->chunk_root_level = root_item->level;
1405
1406         root_item = &root->fs_info->tree_root->root_item;
1407         super->root = root_item->bytenr;
1408         super->generation = root_item->generation;
1409         super->root_level = root_item->level;
1410         if (btrfs_test_opt(root, SPACE_CACHE))
1411                 super->cache_generation = root_item->generation;
1412         if (root->fs_info->update_uuid_tree_gen)
1413                 super->uuid_tree_generation = root_item->generation;
1414 }
1415
1416 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1417 {
1418         struct btrfs_transaction *trans;
1419         int ret = 0;
1420
1421         spin_lock(&info->trans_lock);
1422         trans = info->running_transaction;
1423         if (trans)
1424                 ret = (trans->state >= TRANS_STATE_COMMIT_START);
1425         spin_unlock(&info->trans_lock);
1426         return ret;
1427 }
1428
1429 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1430 {
1431         struct btrfs_transaction *trans;
1432         int ret = 0;
1433
1434         spin_lock(&info->trans_lock);
1435         trans = info->running_transaction;
1436         if (trans)
1437                 ret = is_transaction_blocked(trans);
1438         spin_unlock(&info->trans_lock);
1439         return ret;
1440 }
1441
1442 /*
1443  * wait for the current transaction commit to start and block subsequent
1444  * transaction joins
1445  */
1446 static void wait_current_trans_commit_start(struct btrfs_root *root,
1447                                             struct btrfs_transaction *trans)
1448 {
1449         wait_event(root->fs_info->transaction_blocked_wait,
1450                    trans->state >= TRANS_STATE_COMMIT_START ||
1451                    trans->aborted);
1452 }
1453
1454 /*
1455  * wait for the current transaction to start and then become unblocked.
1456  * caller holds ref.
1457  */
1458 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1459                                          struct btrfs_transaction *trans)
1460 {
1461         wait_event(root->fs_info->transaction_wait,
1462                    trans->state >= TRANS_STATE_UNBLOCKED ||
1463                    trans->aborted);
1464 }
1465
1466 /*
1467  * commit transactions asynchronously. once btrfs_commit_transaction_async
1468  * returns, any subsequent transaction will not be allowed to join.
1469  */
1470 struct btrfs_async_commit {
1471         struct btrfs_trans_handle *newtrans;
1472         struct btrfs_root *root;
1473         struct work_struct work;
1474 };
1475
1476 static void do_async_commit(struct work_struct *work)
1477 {
1478         struct btrfs_async_commit *ac =
1479                 container_of(work, struct btrfs_async_commit, work);
1480
1481         /*
1482          * We've got freeze protection passed with the transaction.
1483          * Tell lockdep about it.
1484          */
1485         if (ac->newtrans->type & __TRANS_FREEZABLE)
1486                 rwsem_acquire_read(
1487                      &ac->root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1488                      0, 1, _THIS_IP_);
1489
1490         current->journal_info = ac->newtrans;
1491
1492         btrfs_commit_transaction(ac->newtrans, ac->root);
1493         kfree(ac);
1494 }
1495
1496 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1497                                    struct btrfs_root *root,
1498                                    int wait_for_unblock)
1499 {
1500         struct btrfs_async_commit *ac;
1501         struct btrfs_transaction *cur_trans;
1502
1503         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1504         if (!ac)
1505                 return -ENOMEM;
1506
1507         INIT_WORK(&ac->work, do_async_commit);
1508         ac->root = root;
1509         ac->newtrans = btrfs_join_transaction(root);
1510         if (IS_ERR(ac->newtrans)) {
1511                 int err = PTR_ERR(ac->newtrans);
1512                 kfree(ac);
1513                 return err;
1514         }
1515
1516         /* take transaction reference */
1517         cur_trans = trans->transaction;
1518         atomic_inc(&cur_trans->use_count);
1519
1520         btrfs_end_transaction(trans, root);
1521
1522         /*
1523          * Tell lockdep we've released the freeze rwsem, since the
1524          * async commit thread will be the one to unlock it.
1525          */
1526         if (ac->newtrans->type & __TRANS_FREEZABLE)
1527                 rwsem_release(
1528                         &root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1529                         1, _THIS_IP_);
1530
1531         schedule_work(&ac->work);
1532
1533         /* wait for transaction to start and unblock */
1534         if (wait_for_unblock)
1535                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1536         else
1537                 wait_current_trans_commit_start(root, cur_trans);
1538
1539         if (current->journal_info == trans)
1540                 current->journal_info = NULL;
1541
1542         btrfs_put_transaction(cur_trans);
1543         return 0;
1544 }
1545
1546
1547 static void cleanup_transaction(struct btrfs_trans_handle *trans,
1548                                 struct btrfs_root *root, int err)
1549 {
1550         struct btrfs_transaction *cur_trans = trans->transaction;
1551         DEFINE_WAIT(wait);
1552
1553         WARN_ON(trans->use_count > 1);
1554
1555         btrfs_abort_transaction(trans, root, err);
1556
1557         spin_lock(&root->fs_info->trans_lock);
1558
1559         /*
1560          * If the transaction is removed from the list, it means this
1561          * transaction has been committed successfully, so it is impossible
1562          * to call the cleanup function.
1563          */
1564         BUG_ON(list_empty(&cur_trans->list));
1565
1566         list_del_init(&cur_trans->list);
1567         if (cur_trans == root->fs_info->running_transaction) {
1568                 cur_trans->state = TRANS_STATE_COMMIT_DOING;
1569                 spin_unlock(&root->fs_info->trans_lock);
1570                 wait_event(cur_trans->writer_wait,
1571                            atomic_read(&cur_trans->num_writers) == 1);
1572
1573                 spin_lock(&root->fs_info->trans_lock);
1574         }
1575         spin_unlock(&root->fs_info->trans_lock);
1576
1577         btrfs_cleanup_one_transaction(trans->transaction, root);
1578
1579         spin_lock(&root->fs_info->trans_lock);
1580         if (cur_trans == root->fs_info->running_transaction)
1581                 root->fs_info->running_transaction = NULL;
1582         spin_unlock(&root->fs_info->trans_lock);
1583
1584         if (trans->type & __TRANS_FREEZABLE)
1585                 sb_end_intwrite(root->fs_info->sb);
1586         btrfs_put_transaction(cur_trans);
1587         btrfs_put_transaction(cur_trans);
1588
1589         trace_btrfs_transaction_commit(root);
1590
1591         btrfs_scrub_continue(root);
1592
1593         if (current->journal_info == trans)
1594                 current->journal_info = NULL;
1595
1596         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1597 }
1598
1599 static int btrfs_flush_all_pending_stuffs(struct btrfs_trans_handle *trans,
1600                                           struct btrfs_root *root)
1601 {
1602         int ret;
1603
1604         ret = btrfs_run_delayed_items(trans, root);
1605         /*
1606          * running the delayed items may have added new refs. account
1607          * them now so that they hinder processing of more delayed refs
1608          * as little as possible.
1609          */
1610         if (ret) {
1611                 btrfs_delayed_refs_qgroup_accounting(trans, root->fs_info);
1612                 return ret;
1613         }
1614
1615         ret = btrfs_delayed_refs_qgroup_accounting(trans, root->fs_info);
1616         if (ret)
1617                 return ret;
1618
1619         /*
1620          * rename don't use btrfs_join_transaction, so, once we
1621          * set the transaction to blocked above, we aren't going
1622          * to get any new ordered operations.  We can safely run
1623          * it here and no for sure that nothing new will be added
1624          * to the list
1625          */
1626         ret = btrfs_run_ordered_operations(trans, root, 1);
1627
1628         return ret;
1629 }
1630
1631 static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)
1632 {
1633         if (btrfs_test_opt(fs_info->tree_root, FLUSHONCOMMIT))
1634                 return btrfs_start_delalloc_roots(fs_info, 1);
1635         return 0;
1636 }
1637
1638 static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
1639 {
1640         if (btrfs_test_opt(fs_info->tree_root, FLUSHONCOMMIT))
1641                 btrfs_wait_ordered_roots(fs_info, -1);
1642 }
1643
1644 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1645                              struct btrfs_root *root)
1646 {
1647         struct btrfs_transaction *cur_trans = trans->transaction;
1648         struct btrfs_transaction *prev_trans = NULL;
1649         int ret;
1650
1651         ret = btrfs_run_ordered_operations(trans, root, 0);
1652         if (ret) {
1653                 btrfs_abort_transaction(trans, root, ret);
1654                 btrfs_end_transaction(trans, root);
1655                 return ret;
1656         }
1657
1658         /* Stop the commit early if ->aborted is set */
1659         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1660                 ret = cur_trans->aborted;
1661                 btrfs_end_transaction(trans, root);
1662                 return ret;
1663         }
1664
1665         /* make a pass through all the delayed refs we have so far
1666          * any runnings procs may add more while we are here
1667          */
1668         ret = btrfs_run_delayed_refs(trans, root, 0);
1669         if (ret) {
1670                 btrfs_end_transaction(trans, root);
1671                 return ret;
1672         }
1673
1674         btrfs_trans_release_metadata(trans, root);
1675         trans->block_rsv = NULL;
1676         if (trans->qgroup_reserved) {
1677                 btrfs_qgroup_free(root, trans->qgroup_reserved);
1678                 trans->qgroup_reserved = 0;
1679         }
1680
1681         cur_trans = trans->transaction;
1682
1683         /*
1684          * set the flushing flag so procs in this transaction have to
1685          * start sending their work down.
1686          */
1687         cur_trans->delayed_refs.flushing = 1;
1688         smp_wmb();
1689
1690         if (!list_empty(&trans->new_bgs))
1691                 btrfs_create_pending_block_groups(trans, root);
1692
1693         ret = btrfs_run_delayed_refs(trans, root, 0);
1694         if (ret) {
1695                 btrfs_end_transaction(trans, root);
1696                 return ret;
1697         }
1698
1699         spin_lock(&root->fs_info->trans_lock);
1700         if (cur_trans->state >= TRANS_STATE_COMMIT_START) {
1701                 spin_unlock(&root->fs_info->trans_lock);
1702                 atomic_inc(&cur_trans->use_count);
1703                 ret = btrfs_end_transaction(trans, root);
1704
1705                 wait_for_commit(root, cur_trans);
1706
1707                 btrfs_put_transaction(cur_trans);
1708
1709                 return ret;
1710         }
1711
1712         cur_trans->state = TRANS_STATE_COMMIT_START;
1713         wake_up(&root->fs_info->transaction_blocked_wait);
1714
1715         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1716                 prev_trans = list_entry(cur_trans->list.prev,
1717                                         struct btrfs_transaction, list);
1718                 if (prev_trans->state != TRANS_STATE_COMPLETED) {
1719                         atomic_inc(&prev_trans->use_count);
1720                         spin_unlock(&root->fs_info->trans_lock);
1721
1722                         wait_for_commit(root, prev_trans);
1723
1724                         btrfs_put_transaction(prev_trans);
1725                 } else {
1726                         spin_unlock(&root->fs_info->trans_lock);
1727                 }
1728         } else {
1729                 spin_unlock(&root->fs_info->trans_lock);
1730         }
1731
1732         extwriter_counter_dec(cur_trans, trans->type);
1733
1734         ret = btrfs_start_delalloc_flush(root->fs_info);
1735         if (ret)
1736                 goto cleanup_transaction;
1737
1738         ret = btrfs_flush_all_pending_stuffs(trans, root);
1739         if (ret)
1740                 goto cleanup_transaction;
1741
1742         wait_event(cur_trans->writer_wait,
1743                    extwriter_counter_read(cur_trans) == 0);
1744
1745         /* some pending stuffs might be added after the previous flush. */
1746         ret = btrfs_flush_all_pending_stuffs(trans, root);
1747         if (ret)
1748                 goto cleanup_transaction;
1749
1750         btrfs_wait_delalloc_flush(root->fs_info);
1751
1752         btrfs_scrub_pause(root);
1753         /*
1754          * Ok now we need to make sure to block out any other joins while we
1755          * commit the transaction.  We could have started a join before setting
1756          * COMMIT_DOING so make sure to wait for num_writers to == 1 again.
1757          */
1758         spin_lock(&root->fs_info->trans_lock);
1759         cur_trans->state = TRANS_STATE_COMMIT_DOING;
1760         spin_unlock(&root->fs_info->trans_lock);
1761         wait_event(cur_trans->writer_wait,
1762                    atomic_read(&cur_trans->num_writers) == 1);
1763
1764         /* ->aborted might be set after the previous check, so check it */
1765         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1766                 ret = cur_trans->aborted;
1767                 goto cleanup_transaction;
1768         }
1769         /*
1770          * the reloc mutex makes sure that we stop
1771          * the balancing code from coming in and moving
1772          * extents around in the middle of the commit
1773          */
1774         mutex_lock(&root->fs_info->reloc_mutex);
1775
1776         /*
1777          * We needn't worry about the delayed items because we will
1778          * deal with them in create_pending_snapshot(), which is the
1779          * core function of the snapshot creation.
1780          */
1781         ret = create_pending_snapshots(trans, root->fs_info);
1782         if (ret) {
1783                 mutex_unlock(&root->fs_info->reloc_mutex);
1784                 goto cleanup_transaction;
1785         }
1786
1787         /*
1788          * We insert the dir indexes of the snapshots and update the inode
1789          * of the snapshots' parents after the snapshot creation, so there
1790          * are some delayed items which are not dealt with. Now deal with
1791          * them.
1792          *
1793          * We needn't worry that this operation will corrupt the snapshots,
1794          * because all the tree which are snapshoted will be forced to COW
1795          * the nodes and leaves.
1796          */
1797         ret = btrfs_run_delayed_items(trans, root);
1798         if (ret) {
1799                 mutex_unlock(&root->fs_info->reloc_mutex);
1800                 goto cleanup_transaction;
1801         }
1802
1803         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1804         if (ret) {
1805                 mutex_unlock(&root->fs_info->reloc_mutex);
1806                 goto cleanup_transaction;
1807         }
1808
1809         /*
1810          * make sure none of the code above managed to slip in a
1811          * delayed item
1812          */
1813         btrfs_assert_delayed_root_empty(root);
1814
1815         WARN_ON(cur_trans != trans->transaction);
1816
1817         /* btrfs_commit_tree_roots is responsible for getting the
1818          * various roots consistent with each other.  Every pointer
1819          * in the tree of tree roots has to point to the most up to date
1820          * root for every subvolume and other tree.  So, we have to keep
1821          * the tree logging code from jumping in and changing any
1822          * of the trees.
1823          *
1824          * At this point in the commit, there can't be any tree-log
1825          * writers, but a little lower down we drop the trans mutex
1826          * and let new people in.  By holding the tree_log_mutex
1827          * from now until after the super is written, we avoid races
1828          * with the tree-log code.
1829          */
1830         mutex_lock(&root->fs_info->tree_log_mutex);
1831
1832         ret = commit_fs_roots(trans, root);
1833         if (ret) {
1834                 mutex_unlock(&root->fs_info->tree_log_mutex);
1835                 mutex_unlock(&root->fs_info->reloc_mutex);
1836                 goto cleanup_transaction;
1837         }
1838
1839         /* commit_fs_roots gets rid of all the tree log roots, it is now
1840          * safe to free the root of tree log roots
1841          */
1842         btrfs_free_log_root_tree(trans, root->fs_info);
1843
1844         ret = commit_cowonly_roots(trans, root);
1845         if (ret) {
1846                 mutex_unlock(&root->fs_info->tree_log_mutex);
1847                 mutex_unlock(&root->fs_info->reloc_mutex);
1848                 goto cleanup_transaction;
1849         }
1850
1851         /*
1852          * The tasks which save the space cache and inode cache may also
1853          * update ->aborted, check it.
1854          */
1855         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1856                 ret = cur_trans->aborted;
1857                 mutex_unlock(&root->fs_info->tree_log_mutex);
1858                 mutex_unlock(&root->fs_info->reloc_mutex);
1859                 goto cleanup_transaction;
1860         }
1861
1862         btrfs_prepare_extent_commit(trans, root);
1863
1864         cur_trans = root->fs_info->running_transaction;
1865
1866         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1867                             root->fs_info->tree_root->node);
1868         switch_commit_root(root->fs_info->tree_root);
1869
1870         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1871                             root->fs_info->chunk_root->node);
1872         switch_commit_root(root->fs_info->chunk_root);
1873
1874         assert_qgroups_uptodate(trans);
1875         update_super_roots(root);
1876
1877         btrfs_set_super_log_root(root->fs_info->super_copy, 0);
1878         btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
1879         memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
1880                sizeof(*root->fs_info->super_copy));
1881
1882         spin_lock(&root->fs_info->trans_lock);
1883         cur_trans->state = TRANS_STATE_UNBLOCKED;
1884         root->fs_info->running_transaction = NULL;
1885         spin_unlock(&root->fs_info->trans_lock);
1886         mutex_unlock(&root->fs_info->reloc_mutex);
1887
1888         wake_up(&root->fs_info->transaction_wait);
1889
1890         ret = btrfs_write_and_wait_transaction(trans, root);
1891         if (ret) {
1892                 btrfs_error(root->fs_info, ret,
1893                             "Error while writing out transaction");
1894                 mutex_unlock(&root->fs_info->tree_log_mutex);
1895                 goto cleanup_transaction;
1896         }
1897
1898         ret = write_ctree_super(trans, root, 0);
1899         if (ret) {
1900                 mutex_unlock(&root->fs_info->tree_log_mutex);
1901                 goto cleanup_transaction;
1902         }
1903
1904         /*
1905          * the super is written, we can safely allow the tree-loggers
1906          * to go about their business
1907          */
1908         mutex_unlock(&root->fs_info->tree_log_mutex);
1909
1910         btrfs_finish_extent_commit(trans, root);
1911
1912         root->fs_info->last_trans_committed = cur_trans->transid;
1913         /*
1914          * We needn't acquire the lock here because there is no other task
1915          * which can change it.
1916          */
1917         cur_trans->state = TRANS_STATE_COMPLETED;
1918         wake_up(&cur_trans->commit_wait);
1919
1920         spin_lock(&root->fs_info->trans_lock);
1921         list_del_init(&cur_trans->list);
1922         spin_unlock(&root->fs_info->trans_lock);
1923
1924         btrfs_put_transaction(cur_trans);
1925         btrfs_put_transaction(cur_trans);
1926
1927         if (trans->type & __TRANS_FREEZABLE)
1928                 sb_end_intwrite(root->fs_info->sb);
1929
1930         trace_btrfs_transaction_commit(root);
1931
1932         btrfs_scrub_continue(root);
1933
1934         if (current->journal_info == trans)
1935                 current->journal_info = NULL;
1936
1937         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1938
1939         if (current != root->fs_info->transaction_kthread)
1940                 btrfs_run_delayed_iputs(root);
1941
1942         return ret;
1943
1944 cleanup_transaction:
1945         btrfs_trans_release_metadata(trans, root);
1946         trans->block_rsv = NULL;
1947         if (trans->qgroup_reserved) {
1948                 btrfs_qgroup_free(root, trans->qgroup_reserved);
1949                 trans->qgroup_reserved = 0;
1950         }
1951         btrfs_warn(root->fs_info, "Skipping commit of aborted transaction.");
1952         if (current->journal_info == trans)
1953                 current->journal_info = NULL;
1954         cleanup_transaction(trans, root, ret);
1955
1956         return ret;
1957 }
1958
1959 /*
1960  * return < 0 if error
1961  * 0 if there are no more dead_roots at the time of call
1962  * 1 there are more to be processed, call me again
1963  *
1964  * The return value indicates there are certainly more snapshots to delete, but
1965  * if there comes a new one during processing, it may return 0. We don't mind,
1966  * because btrfs_commit_super will poke cleaner thread and it will process it a
1967  * few seconds later.
1968  */
1969 int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root)
1970 {
1971         int ret;
1972         struct btrfs_fs_info *fs_info = root->fs_info;
1973
1974         spin_lock(&fs_info->trans_lock);
1975         if (list_empty(&fs_info->dead_roots)) {
1976                 spin_unlock(&fs_info->trans_lock);
1977                 return 0;
1978         }
1979         root = list_first_entry(&fs_info->dead_roots,
1980                         struct btrfs_root, root_list);
1981         list_del_init(&root->root_list);
1982         spin_unlock(&fs_info->trans_lock);
1983
1984         pr_debug("btrfs: cleaner removing %llu\n", root->objectid);
1985
1986         btrfs_kill_all_delayed_nodes(root);
1987
1988         if (btrfs_header_backref_rev(root->node) <
1989                         BTRFS_MIXED_BACKREF_REV)
1990                 ret = btrfs_drop_snapshot(root, NULL, 0, 0);
1991         else
1992                 ret = btrfs_drop_snapshot(root, NULL, 1, 0);
1993         /*
1994          * If we encounter a transaction abort during snapshot cleaning, we
1995          * don't want to crash here
1996          */
1997         return (ret < 0) ? 0 : 1;
1998 }