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 #include "qgroup.h"
  35
  36 #define BTRFS_ROOT_TRANS_TAG 0
  37
  38 static unsigned int btrfs_blocked_trans_types[TRANS_STATE_MAX] = {
  39         [TRANS_STATE_RUNNING]           = 0U,
  40         [TRANS_STATE_BLOCKED]           = (__TRANS_USERSPACE |
  41                                            __TRANS_START),
  42         [TRANS_STATE_COMMIT_START]      = (__TRANS_USERSPACE |
  43                                            __TRANS_START |
  44                                            __TRANS_ATTACH),
  45         [TRANS_STATE_COMMIT_DOING]      = (__TRANS_USERSPACE |
  46                                            __TRANS_START |
  47                                            __TRANS_ATTACH |
  48                                            __TRANS_JOIN),
  49         [TRANS_STATE_UNBLOCKED]         = (__TRANS_USERSPACE |
  50                                            __TRANS_START |
  51                                            __TRANS_ATTACH |
  52                                            __TRANS_JOIN |
  53                                            __TRANS_JOIN_NOLOCK),
  54         [TRANS_STATE_COMPLETED]         = (__TRANS_USERSPACE |
  55                                            __TRANS_START |
  56                                            __TRANS_ATTACH |
  57                                            __TRANS_JOIN |
  58                                            __TRANS_JOIN_NOLOCK),
  59 };
  60
  61 void btrfs_put_transaction(struct btrfs_transaction *transaction)
  62 {
  63         WARN_ON(atomic_read(&transaction->use_count) == 0);
  64         if (atomic_dec_and_test(&transaction->use_count)) {
  65                 BUG_ON(!list_empty(&transaction->list));
  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_roots(struct btrfs_transaction *trans,
  80                                          struct btrfs_fs_info *fs_info)
  81 {
  82         struct btrfs_root *root, *tmp;
  83
  84         down_write(&fs_info->commit_root_sem);
  85         list_for_each_entry_safe(root, tmp, &trans->switch_commits,
  86                                  dirty_list) {
  87                 list_del_init(&root->dirty_list);
  88                 free_extent_buffer(root->commit_root);
  89                 root->commit_root = btrfs_root_node(root);
  90                 if (is_fstree(root->objectid))
  91                         btrfs_unpin_free_ino(root);
  92         }
  93         up_write(&fs_info->commit_root_sem);
  94 }
  95
  96 static inline void extwriter_counter_inc(struct btrfs_transaction *trans,
  97                                          unsigned int type)
  98 {
  99         if (type & TRANS_EXTWRITERS)
 100                 atomic_inc(&trans->num_extwriters);
 101 }
 102
 103 static inline void extwriter_counter_dec(struct btrfs_transaction *trans,
 104                                          unsigned int type)
 105 {
 106         if (type & TRANS_EXTWRITERS)
 107                 atomic_dec(&trans->num_extwriters);
 108 }
 109
 110 static inline void extwriter_counter_init(struct btrfs_transaction *trans,
 111                                           unsigned int type)
 112 {
 113         atomic_set(&trans->num_extwriters, ((type & TRANS_EXTWRITERS) ? 1 : 0));
 114 }
 115
 116 static inline int extwriter_counter_read(struct btrfs_transaction *trans)
 117 {
 118         return atomic_read(&trans->num_extwriters);
 119 }
 120
 121 /*
 122  * either allocate a new transaction or hop into the existing one
 123  */
 124 static noinline int join_transaction(struct btrfs_root *root, unsigned int type)
 125 {
 126         struct btrfs_transaction *cur_trans;
 127         struct btrfs_fs_info *fs_info = root->fs_info;
 128
 129         spin_lock(&fs_info->trans_lock);
 130 loop:
 131         /* The file system has been taken offline. No new transactions. */
 132         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 133                 spin_unlock(&fs_info->trans_lock);
 134                 return -EROFS;
 135         }
 136
 137         cur_trans = fs_info->running_transaction;
 138         if (cur_trans) {
 139                 if (cur_trans->aborted) {
 140                         spin_unlock(&fs_info->trans_lock);
 141                         return cur_trans->aborted;
 142                 }
 143                 if (btrfs_blocked_trans_types[cur_trans->state] & type) {
 144                         spin_unlock(&fs_info->trans_lock);
 145                         return -EBUSY;
 146                 }
 147                 atomic_inc(&cur_trans->use_count);
 148                 atomic_inc(&cur_trans->num_writers);
 149                 extwriter_counter_inc(cur_trans, type);
 150                 spin_unlock(&fs_info->trans_lock);
 151                 return 0;
 152         }
 153         spin_unlock(&fs_info->trans_lock);
 154
 155         /*
 156          * If we are ATTACH, we just want to catch the current transaction,
 157          * and commit it. If there is no transaction, just return ENOENT.
 158          */
 159         if (type == TRANS_ATTACH)
 160                 return -ENOENT;
 161
 162         /*
 163          * JOIN_NOLOCK only happens during the transaction commit, so
 164          * it is impossible that ->running_transaction is NULL
 165          */
 166         BUG_ON(type == TRANS_JOIN_NOLOCK);
 167
 168         cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
 169         if (!cur_trans)
 170                 return -ENOMEM;
 171
 172         spin_lock(&fs_info->trans_lock);
 173         if (fs_info->running_transaction) {
 174                 /*
 175                  * someone started a transaction after we unlocked.  Make sure
 176                  * to redo the checks above
 177                  */
 178                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 179                 goto loop;
 180         } else if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 181                 spin_unlock(&fs_info->trans_lock);
 182                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 183                 return -EROFS;
 184         }
 185
 186         atomic_set(&cur_trans->num_writers, 1);
 187         extwriter_counter_init(cur_trans, type);
 188         init_waitqueue_head(&cur_trans->writer_wait);
 189         init_waitqueue_head(&cur_trans->commit_wait);
 190         cur_trans->state = TRANS_STATE_RUNNING;
 191         /*
 192          * One for this trans handle, one so it will live on until we
 193          * commit the transaction.
 194          */
 195         atomic_set(&cur_trans->use_count, 2);
 196         cur_trans->start_time = get_seconds();
 197
 198         cur_trans->delayed_refs.href_root = RB_ROOT;
 199         atomic_set(&cur_trans->delayed_refs.num_entries, 0);
 200         cur_trans->delayed_refs.num_heads_ready = 0;
 201         cur_trans->delayed_refs.num_heads = 0;
 202         cur_trans->delayed_refs.flushing = 0;
 203         cur_trans->delayed_refs.run_delayed_start = 0;
 204
 205         /*
 206          * although the tree mod log is per file system and not per transaction,
 207          * the log must never go across transaction boundaries.
 208          */
 209         smp_mb();
 210         if (!list_empty(&fs_info->tree_mod_seq_list))
 211                 WARN(1, KERN_ERR "BTRFS: tree_mod_seq_list not empty when "
 212                         "creating a fresh transaction\n");
 213         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log))
 214                 WARN(1, KERN_ERR "BTRFS: tree_mod_log rb tree not empty when "
 215                         "creating a fresh transaction\n");
 216         atomic64_set(&fs_info->tree_mod_seq, 0);
 217
 218         spin_lock_init(&cur_trans->delayed_refs.lock);
 219
 220         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 221         INIT_LIST_HEAD(&cur_trans->ordered_operations);
 222         INIT_LIST_HEAD(&cur_trans->pending_chunks);
 223         INIT_LIST_HEAD(&cur_trans->switch_commits);
 224         list_add_tail(&cur_trans->list, &fs_info->trans_list);
 225         extent_io_tree_init(&cur_trans->dirty_pages,
 226                              fs_info->btree_inode->i_mapping);
 227         fs_info->generation++;
 228         cur_trans->transid = fs_info->generation;
 229         fs_info->running_transaction = cur_trans;
 230         cur_trans->aborted = 0;
 231         spin_unlock(&fs_info->trans_lock);
 232
 233         return 0;
 234 }
 235
 236 /*
 237  * this does all the record keeping required to make sure that a reference
 238  * counted root is properly recorded in a given transaction.  This is required
 239  * to make sure the old root from before we joined the transaction is deleted
 240  * when the transaction commits
 241  */
 242 static int record_root_in_trans(struct btrfs_trans_handle *trans,
 243                                struct btrfs_root *root)
 244 {
 245         if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
 246             root->last_trans < trans->transid) {
 247                 WARN_ON(root == root->fs_info->extent_root);
 248                 WARN_ON(root->commit_root != root->node);
 249
 250                 /*
 251                  * see below for IN_TRANS_SETUP usage rules
 252                  * we have the reloc mutex held now, so there
 253                  * is only one writer in this function
 254                  */
 255                 set_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
 256
 257                 /* make sure readers find IN_TRANS_SETUP before
 258                  * they find our root->last_trans update
 259                  */
 260                 smp_wmb();
 261
 262                 spin_lock(&root->fs_info->fs_roots_radix_lock);
 263                 if (root->last_trans == trans->transid) {
 264                         spin_unlock(&root->fs_info->fs_roots_radix_lock);
 265                         return 0;
 266                 }
 267                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 268                            (unsigned long)root->root_key.objectid,
 269                            BTRFS_ROOT_TRANS_TAG);
 270                 spin_unlock(&root->fs_info->fs_roots_radix_lock);
 271                 root->last_trans = trans->transid;
 272
 273                 /* this is pretty tricky.  We don't want to
 274                  * take the relocation lock in btrfs_record_root_in_trans
 275                  * unless we're really doing the first setup for this root in
 276                  * this transaction.
 277                  *
 278                  * Normally we'd use root->last_trans as a flag to decide
 279                  * if we want to take the expensive mutex.
 280                  *
 281                  * But, we have to set root->last_trans before we
 282                  * init the relocation root, otherwise, we trip over warnings
 283                  * in ctree.c.  The solution used here is to flag ourselves
 284                  * with root IN_TRANS_SETUP.  When this is 1, we're still
 285                  * fixing up the reloc trees and everyone must wait.
 286                  *
 287                  * When this is zero, they can trust root->last_trans and fly
 288                  * through btrfs_record_root_in_trans without having to take the
 289                  * lock.  smp_wmb() makes sure that all the writes above are
 290                  * done before we pop in the zero below
 291                  */
 292                 btrfs_init_reloc_root(trans, root);
 293                 smp_mb__before_atomic();
 294                 clear_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
 295         }
 296         return 0;
 297 }
 298
 299
 300 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 301                                struct btrfs_root *root)
 302 {
 303         if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 304                 return 0;
 305
 306         /*
 307          * see record_root_in_trans for comments about IN_TRANS_SETUP usage
 308          * and barriers
 309          */
 310         smp_rmb();
 311         if (root->last_trans == trans->transid &&
 312             !test_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state))
 313                 return 0;
 314
 315         mutex_lock(&root->fs_info->reloc_mutex);
 316         record_root_in_trans(trans, root);
 317         mutex_unlock(&root->fs_info->reloc_mutex);
 318
 319         return 0;
 320 }
 321
 322 static inline int is_transaction_blocked(struct btrfs_transaction *trans)
 323 {
 324         return (trans->state >= TRANS_STATE_BLOCKED &&
 325                 trans->state < TRANS_STATE_UNBLOCKED &&
 326                 !trans->aborted);
 327 }
 328
 329 /* wait for commit against the current transaction to become unblocked
 330  * when this is done, it is safe to start a new transaction, but the current
 331  * transaction might not be fully on disk.
 332  */
 333 static void wait_current_trans(struct btrfs_root *root)
 334 {
 335         struct btrfs_transaction *cur_trans;
 336
 337         spin_lock(&root->fs_info->trans_lock);
 338         cur_trans = root->fs_info->running_transaction;
 339         if (cur_trans && is_transaction_blocked(cur_trans)) {
 340                 atomic_inc(&cur_trans->use_count);
 341                 spin_unlock(&root->fs_info->trans_lock);
 342
 343                 wait_event(root->fs_info->transaction_wait,
 344                            cur_trans->state >= TRANS_STATE_UNBLOCKED ||
 345                            cur_trans->aborted);
 346                 btrfs_put_transaction(cur_trans);
 347         } else {
 348                 spin_unlock(&root->fs_info->trans_lock);
 349         }
 350 }
 351
 352 static int may_wait_transaction(struct btrfs_root *root, int type)
 353 {
 354         if (root->fs_info->log_root_recovering)
 355                 return 0;
 356
 357         if (type == TRANS_USERSPACE)
 358                 return 1;
 359
 360         if (type == TRANS_START &&
 361             !atomic_read(&root->fs_info->open_ioctl_trans))
 362                 return 1;
 363
 364         return 0;
 365 }
 366
 367 static inline bool need_reserve_reloc_root(struct btrfs_root *root)
 368 {
 369         if (!root->fs_info->reloc_ctl ||
 370             !test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
 371             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 372             root->reloc_root)
 373                 return false;
 374
 375         return true;
 376 }
 377
 378 static struct btrfs_trans_handle *
 379 start_transaction(struct btrfs_root *root, u64 num_items, unsigned int type,
 380                   enum btrfs_reserve_flush_enum flush)
 381 {
 382         struct btrfs_trans_handle *h;
 383         struct btrfs_transaction *cur_trans;
 384         u64 num_bytes = 0;
 385         u64 qgroup_reserved = 0;
 386         bool reloc_reserved = false;
 387         int ret;
 388
 389         /* Send isn't supposed to start transactions. */
 390         ASSERT(current->journal_info != (void *)BTRFS_SEND_TRANS_STUB);
 391
 392         if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state))
 393                 return ERR_PTR(-EROFS);
 394
 395         if (current->journal_info) {
 396                 WARN_ON(type & TRANS_EXTWRITERS);
 397                 h = current->journal_info;
 398                 h->use_count++;
 399                 WARN_ON(h->use_count > 2);
 400                 h->orig_rsv = h->block_rsv;
 401                 h->block_rsv = NULL;
 402                 goto got_it;
 403         }
 404
 405         /*
 406          * Do the reservation before we join the transaction so we can do all
 407          * the appropriate flushing if need be.
 408          */
 409         if (num_items > 0 && root != root->fs_info->chunk_root) {
 410                 if (root->fs_info->quota_enabled &&
 411                     is_fstree(root->root_key.objectid)) {
 412                         qgroup_reserved = num_items * root->leafsize;
 413                         ret = btrfs_qgroup_reserve(root, qgroup_reserved);
 414                         if (ret)
 415                                 return ERR_PTR(ret);
 416                 }
 417
 418                 num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
 419                 /*
 420                  * Do the reservation for the relocation root creation
 421                  */
 422                 if (unlikely(need_reserve_reloc_root(root))) {
 423                         num_bytes += root->nodesize;
 424                         reloc_reserved = true;
 425                 }
 426
 427                 ret = btrfs_block_rsv_add(root,
 428                                           &root->fs_info->trans_block_rsv,
 429                                           num_bytes, flush);
 430                 if (ret)
 431                         goto reserve_fail;
 432         }
 433 again:
 434         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 435         if (!h) {
 436                 ret = -ENOMEM;
 437                 goto alloc_fail;
 438         }
 439
 440         /*
 441          * If we are JOIN_NOLOCK we're already committing a transaction and
 442          * waiting on this guy, so we don't need to do the sb_start_intwrite
 443          * because we're already holding a ref.  We need this because we could
 444          * have raced in and did an fsync() on a file which can kick a commit
 445          * and then we deadlock with somebody doing a freeze.
 446          *
 447          * If we are ATTACH, it means we just want to catch the current
 448          * transaction and commit it, so we needn't do sb_start_intwrite().
 449          */
 450         if (type & __TRANS_FREEZABLE)
 451                 sb_start_intwrite(root->fs_info->sb);
 452
 453         if (may_wait_transaction(root, type))
 454                 wait_current_trans(root);
 455
 456         do {
 457                 ret = join_transaction(root, type);
 458                 if (ret == -EBUSY) {
 459                         wait_current_trans(root);
 460                         if (unlikely(type == TRANS_ATTACH))
 461                                 ret = -ENOENT;
 462                 }
 463         } while (ret == -EBUSY);
 464
 465         if (ret < 0) {
 466                 /* We must get the transaction if we are JOIN_NOLOCK. */
 467                 BUG_ON(type == TRANS_JOIN_NOLOCK);
 468                 goto join_fail;
 469         }
 470
 471         cur_trans = root->fs_info->running_transaction;
 472
 473         h->transid = cur_trans->transid;
 474         h->transaction = cur_trans;
 475         h->blocks_used = 0;
 476         h->bytes_reserved = 0;
 477         h->root = root;
 478         h->delayed_ref_updates = 0;
 479         h->use_count = 1;
 480         h->adding_csums = 0;
 481         h->block_rsv = NULL;
 482         h->orig_rsv = NULL;
 483         h->aborted = 0;
 484         h->qgroup_reserved = 0;
 485         h->delayed_ref_elem.seq = 0;
 486         h->type = type;
 487         h->allocating_chunk = false;
 488         h->reloc_reserved = false;
 489         h->sync = false;
 490         INIT_LIST_HEAD(&h->qgroup_ref_list);
 491         INIT_LIST_HEAD(&h->new_bgs);
 492
 493         smp_mb();
 494         if (cur_trans->state >= TRANS_STATE_BLOCKED &&
 495             may_wait_transaction(root, type)) {
 496                 current->journal_info = h;
 497                 btrfs_commit_transaction(h, root);
 498                 goto again;
 499         }
 500
 501         if (num_bytes) {
 502                 trace_btrfs_space_reservation(root->fs_info, "transaction",
 503                                               h->transid, num_bytes, 1);
 504                 h->block_rsv = &root->fs_info->trans_block_rsv;
 505                 h->bytes_reserved = num_bytes;
 506                 h->reloc_reserved = reloc_reserved;
 507         }
 508         h->qgroup_reserved = qgroup_reserved;
 509
 510 got_it:
 511         btrfs_record_root_in_trans(h, root);
 512
 513         if (!current->journal_info && type != TRANS_USERSPACE)
 514                 current->journal_info = h;
 515         return h;
 516
 517 join_fail:
 518         if (type & __TRANS_FREEZABLE)
 519                 sb_end_intwrite(root->fs_info->sb);
 520         kmem_cache_free(btrfs_trans_handle_cachep, h);
 521 alloc_fail:
 522         if (num_bytes)
 523                 btrfs_block_rsv_release(root, &root->fs_info->trans_block_rsv,
 524                                         num_bytes);
 525 reserve_fail:
 526         if (qgroup_reserved)
 527                 btrfs_qgroup_free(root, qgroup_reserved);
 528         return ERR_PTR(ret);
 529 }
 530
 531 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 532                                                    int num_items)
 533 {
 534         return start_transaction(root, num_items, TRANS_START,
 535                                  BTRFS_RESERVE_FLUSH_ALL);
 536 }
 537
 538 struct btrfs_trans_handle *btrfs_start_transaction_lflush(
 539                                         struct btrfs_root *root, int num_items)
 540 {
 541         return start_transaction(root, num_items, TRANS_START,
 542                                  BTRFS_RESERVE_FLUSH_LIMIT);
 543 }
 544
 545 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 546 {
 547         return start_transaction(root, 0, TRANS_JOIN, 0);
 548 }
 549
 550 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
 551 {
 552         return start_transaction(root, 0, TRANS_JOIN_NOLOCK, 0);
 553 }
 554
 555 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 556 {
 557         return start_transaction(root, 0, TRANS_USERSPACE, 0);
 558 }
 559
 560 /*
 561  * btrfs_attach_transaction() - catch the running transaction
 562  *
 563  * It is used when we want to commit the current the transaction, but
 564  * don't want to start a new one.
 565  *
 566  * Note: If this function return -ENOENT, it just means there is no
 567  * running transaction. But it is possible that the inactive transaction
 568  * is still in the memory, not fully on disk. If you hope there is no
 569  * inactive transaction in the fs when -ENOENT is returned, you should
 570  * invoke
 571  *     btrfs_attach_transaction_barrier()
 572  */
 573 struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
 574 {
 575         return start_transaction(root, 0, TRANS_ATTACH, 0);
 576 }
 577
 578 /*
 579  * btrfs_attach_transaction_barrier() - catch the running transaction
 580  *
 581  * It is similar to the above function, the differentia is this one
 582  * will wait for all the inactive transactions until they fully
 583  * complete.
 584  */
 585 struct btrfs_trans_handle *
 586 btrfs_attach_transaction_barrier(struct btrfs_root *root)
 587 {
 588         struct btrfs_trans_handle *trans;
 589
 590         trans = start_transaction(root, 0, TRANS_ATTACH, 0);
 591         if (IS_ERR(trans) && PTR_ERR(trans) == -ENOENT)
 592                 btrfs_wait_for_commit(root, 0);
 593
 594         return trans;
 595 }
 596
 597 /* wait for a transaction commit to be fully complete */
 598 static noinline void wait_for_commit(struct btrfs_root *root,
 599                                     struct btrfs_transaction *commit)
 600 {
 601         wait_event(commit->commit_wait, commit->state == TRANS_STATE_COMPLETED);
 602 }
 603
 604 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 605 {
 606         struct btrfs_transaction *cur_trans = NULL, *t;
 607         int ret = 0;
 608
 609         if (transid) {
 610                 if (transid <= root->fs_info->last_trans_committed)
 611                         goto out;
 612
 613                 ret = -EINVAL;
 614                 /* find specified transaction */
 615                 spin_lock(&root->fs_info->trans_lock);
 616                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 617                         if (t->transid == transid) {
 618                                 cur_trans = t;
 619                                 atomic_inc(&cur_trans->use_count);
 620                                 ret = 0;
 621                                 break;
 622                         }
 623                         if (t->transid > transid) {
 624                                 ret = 0;
 625                                 break;
 626                         }
 627                 }
 628                 spin_unlock(&root->fs_info->trans_lock);
 629                 /* The specified transaction doesn't exist */
 630                 if (!cur_trans)
 631                         goto out;
 632         } else {
 633                 /* find newest transaction that is committing | committed */
 634                 spin_lock(&root->fs_info->trans_lock);
 635                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 636                                             list) {
 637                         if (t->state >= TRANS_STATE_COMMIT_START) {
 638                                 if (t->state == TRANS_STATE_COMPLETED)
 639                                         break;
 640                                 cur_trans = t;
 641                                 atomic_inc(&cur_trans->use_count);
 642                                 break;
 643                         }
 644                 }
 645                 spin_unlock(&root->fs_info->trans_lock);
 646                 if (!cur_trans)
 647                         goto out;  /* nothing committing|committed */
 648         }
 649
 650         wait_for_commit(root, cur_trans);
 651         btrfs_put_transaction(cur_trans);
 652 out:
 653         return ret;
 654 }
 655
 656 void btrfs_throttle(struct btrfs_root *root)
 657 {
 658         if (!atomic_read(&root->fs_info->open_ioctl_trans))
 659                 wait_current_trans(root);
 660 }
 661
 662 static int should_end_transaction(struct btrfs_trans_handle *trans,
 663                                   struct btrfs_root *root)
 664 {
 665         if (root->fs_info->global_block_rsv.space_info->full &&
 666             btrfs_check_space_for_delayed_refs(trans, root))
 667                 return 1;
 668
 669         return !!btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
 670 }
 671
 672 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 673                                  struct btrfs_root *root)
 674 {
 675         struct btrfs_transaction *cur_trans = trans->transaction;
 676         int updates;
 677         int err;
 678
 679         smp_mb();
 680         if (cur_trans->state >= TRANS_STATE_BLOCKED ||
 681             cur_trans->delayed_refs.flushing)
 682                 return 1;
 683
 684         updates = trans->delayed_ref_updates;
 685         trans->delayed_ref_updates = 0;
 686         if (updates) {
 687                 err = btrfs_run_delayed_refs(trans, root, updates);
 688                 if (err) /* Error code will also eval true */
 689                         return err;
 690         }
 691
 692         return should_end_transaction(trans, root);
 693 }
 694
 695 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 696                           struct btrfs_root *root, int throttle)
 697 {
 698         struct btrfs_transaction *cur_trans = trans->transaction;
 699         struct btrfs_fs_info *info = root->fs_info;
 700         unsigned long cur = trans->delayed_ref_updates;
 701         int lock = (trans->type != TRANS_JOIN_NOLOCK);
 702         int err = 0;
 703         int must_run_delayed_refs = 0;
 704
 705         if (trans->use_count > 1) {
 706                 trans->use_count--;
 707                 trans->block_rsv = trans->orig_rsv;
 708                 return 0;
 709         }
 710
 711         btrfs_trans_release_metadata(trans, root);
 712         trans->block_rsv = NULL;
 713
 714         if (!list_empty(&trans->new_bgs))
 715                 btrfs_create_pending_block_groups(trans, root);
 716
 717         trans->delayed_ref_updates = 0;
 718         if (!trans->sync) {
 719                 must_run_delayed_refs =
 720                         btrfs_should_throttle_delayed_refs(trans, root);
 721                 cur = max_t(unsigned long, cur, 32);
 722
 723                 /*
 724                  * don't make the caller wait if they are from a NOLOCK
 725                  * or ATTACH transaction, it will deadlock with commit
 726                  */
 727                 if (must_run_delayed_refs == 1 &&
 728                     (trans->type & (__TRANS_JOIN_NOLOCK | __TRANS_ATTACH)))
 729                         must_run_delayed_refs = 2;
 730         }
 731
 732         if (trans->qgroup_reserved) {
 733                 /*
 734                  * the same root has to be passed here between start_transaction
 735                  * and end_transaction. Subvolume quota depends on this.
 736                  */
 737                 btrfs_qgroup_free(trans->root, trans->qgroup_reserved);
 738                 trans->qgroup_reserved = 0;
 739         }
 740
 741         btrfs_trans_release_metadata(trans, root);
 742         trans->block_rsv = NULL;
 743
 744         if (!list_empty(&trans->new_bgs))
 745                 btrfs_create_pending_block_groups(trans, root);
 746
 747         if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
 748             should_end_transaction(trans, root) &&
 749             ACCESS_ONCE(cur_trans->state) == TRANS_STATE_RUNNING) {
 750                 spin_lock(&info->trans_lock);
 751                 if (cur_trans->state == TRANS_STATE_RUNNING)
 752                         cur_trans->state = TRANS_STATE_BLOCKED;
 753                 spin_unlock(&info->trans_lock);
 754         }
 755
 756         if (lock && ACCESS_ONCE(cur_trans->state) == TRANS_STATE_BLOCKED) {
 757                 if (throttle)
 758                         return btrfs_commit_transaction(trans, root);
 759                 else
 760                         wake_up_process(info->transaction_kthread);
 761         }
 762
 763         if (trans->type & __TRANS_FREEZABLE)
 764                 sb_end_intwrite(root->fs_info->sb);
 765
 766         WARN_ON(cur_trans != info->running_transaction);
 767         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 768         atomic_dec(&cur_trans->num_writers);
 769         extwriter_counter_dec(cur_trans, trans->type);
 770
 771         smp_mb();
 772         if (waitqueue_active(&cur_trans->writer_wait))
 773                 wake_up(&cur_trans->writer_wait);
 774         btrfs_put_transaction(cur_trans);
 775
 776         if (current->journal_info == trans)
 777                 current->journal_info = NULL;
 778
 779         if (throttle)
 780                 btrfs_run_delayed_iputs(root);
 781
 782         if (trans->aborted ||
 783             test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) {
 784                 wake_up_process(info->transaction_kthread);
 785                 err = -EIO;
 786         }
 787         assert_qgroups_uptodate(trans);
 788
 789         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 790         if (must_run_delayed_refs) {
 791                 btrfs_async_run_delayed_refs(root, cur,
 792                                              must_run_delayed_refs == 1);
 793         }
 794         return err;
 795 }
 796
 797 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 798                           struct btrfs_root *root)
 799 {
 800         return __btrfs_end_transaction(trans, root, 0);
 801 }
 802
 803 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 804                                    struct btrfs_root *root)
 805 {
 806         return __btrfs_end_transaction(trans, root, 1);
 807 }
 808
 809 /*
 810  * when btree blocks are allocated, they have some corresponding bits set for
 811  * them in one of two extent_io trees.  This is used to make sure all of
 812  * those extents are sent to disk but does not wait on them
 813  */
 814 int btrfs_write_marked_extents(struct btrfs_root *root,
 815                                struct extent_io_tree *dirty_pages, int mark)
 816 {
 817         int err = 0;
 818         int werr = 0;
 819         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 820         struct extent_state *cached_state = NULL;
 821         u64 start = 0;
 822         u64 end;
 823
 824         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 825                                       mark, &cached_state)) {
 826                 convert_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT,
 827                                    mark, &cached_state, GFP_NOFS);
 828                 cached_state = NULL;
 829                 err = filemap_fdatawrite_range(mapping, start, end);
 830                 if (err)
 831                         werr = err;
 832                 cond_resched();
 833                 start = end + 1;
 834         }
 835         if (err)
 836                 werr = err;
 837         return werr;
 838 }
 839
 840 /*
 841  * when btree blocks are allocated, they have some corresponding bits set for
 842  * them in one of two extent_io trees.  This is used to make sure all of
 843  * those extents are on disk for transaction or log commit.  We wait
 844  * on all the pages and clear them from the dirty pages state tree
 845  */
 846 int btrfs_wait_marked_extents(struct btrfs_root *root,
 847                               struct extent_io_tree *dirty_pages, int mark)
 848 {
 849         int err = 0;
 850         int werr = 0;
 851         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 852         struct extent_state *cached_state = NULL;
 853         u64 start = 0;
 854         u64 end;
 855
 856         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 857                                       EXTENT_NEED_WAIT, &cached_state)) {
 858                 clear_extent_bit(dirty_pages, start, end, EXTENT_NEED_WAIT,
 859                                  0, 0, &cached_state, GFP_NOFS);
 860                 err = filemap_fdatawait_range(mapping, start, end);
 861                 if (err)
 862                         werr = err;
 863                 cond_resched();
 864                 start = end + 1;
 865         }
 866         if (err)
 867                 werr = err;
 868         return werr;
 869 }
 870
 871 /*
 872  * when btree blocks are allocated, they have some corresponding bits set for
 873  * them in one of two extent_io trees.  This is used to make sure all of
 874  * those extents are on disk for transaction or log commit
 875  */
 876 static int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 877                                 struct extent_io_tree *dirty_pages, int mark)
 878 {
 879         int ret;
 880         int ret2;
 881         struct blk_plug plug;
 882
 883         blk_start_plug(&plug);
 884         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 885         blk_finish_plug(&plug);
 886         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 887
 888         if (ret)
 889                 return ret;
 890         if (ret2)
 891                 return ret2;
 892         return 0;
 893 }
 894
 895 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 896                                      struct btrfs_root *root)
 897 {
 898         if (!trans || !trans->transaction) {
 899                 struct inode *btree_inode;
 900                 btree_inode = root->fs_info->btree_inode;
 901                 return filemap_write_and_wait(btree_inode->i_mapping);
 902         }
 903         return btrfs_write_and_wait_marked_extents(root,
 904                                            &trans->transaction->dirty_pages,
 905                                            EXTENT_DIRTY);
 906 }
 907
 908 /*
 909  * this is used to update the root pointer in the tree of tree roots.
 910  *
 911  * But, in the case of the extent allocation tree, updating the root
 912  * pointer may allocate blocks which may change the root of the extent
 913  * allocation tree.
 914  *
 915  * So, this loops and repeats and makes sure the cowonly root didn't
 916  * change while the root pointer was being updated in the metadata.
 917  */
 918 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 919                                struct btrfs_root *root)
 920 {
 921         int ret;
 922         u64 old_root_bytenr;
 923         u64 old_root_used;
 924         struct btrfs_root *tree_root = root->fs_info->tree_root;
 925
 926         old_root_used = btrfs_root_used(&root->root_item);
 927         btrfs_write_dirty_block_groups(trans, root);
 928
 929         while (1) {
 930                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 931                 if (old_root_bytenr == root->node->start &&
 932                     old_root_used == btrfs_root_used(&root->root_item))
 933                         break;
 934
 935                 btrfs_set_root_node(&root->root_item, root->node);
 936                 ret = btrfs_update_root(trans, tree_root,
 937                                         &root->root_key,
 938                                         &root->root_item);
 939                 if (ret)
 940                         return ret;
 941
 942                 old_root_used = btrfs_root_used(&root->root_item);
 943                 ret = btrfs_write_dirty_block_groups(trans, root);
 944                 if (ret)
 945                         return ret;
 946         }
 947
 948         return 0;
 949 }
 950
 951 /*
 952  * update all the cowonly tree roots on disk
 953  *
 954  * The error handling in this function may not be obvious. Any of the
 955  * failures will cause the file system to go offline. We still need
 956  * to clean up the delayed refs.
 957  */
 958 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 959                                          struct btrfs_root *root)
 960 {
 961         struct btrfs_fs_info *fs_info = root->fs_info;
 962         struct list_head *next;
 963         struct extent_buffer *eb;
 964         int ret;
 965
 966         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 967         if (ret)
 968                 return ret;
 969
 970         eb = btrfs_lock_root_node(fs_info->tree_root);
 971         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
 972                               0, &eb);
 973         btrfs_tree_unlock(eb);
 974         free_extent_buffer(eb);
 975
 976         if (ret)
 977                 return ret;
 978
 979         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 980         if (ret)
 981                 return ret;
 982
 983         ret = btrfs_run_dev_stats(trans, root->fs_info);
 984         if (ret)
 985                 return ret;
 986         ret = btrfs_run_dev_replace(trans, root->fs_info);
 987         if (ret)
 988                 return ret;
 989         ret = btrfs_run_qgroups(trans, root->fs_info);
 990         if (ret)
 991                 return ret;
 992
 993         /* run_qgroups might have added some more refs */
 994         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 995         if (ret)
 996                 return ret;
 997
 998         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 999                 next = fs_info->dirty_cowonly_roots.next;
1000                 list_del_init(next);
1001                 root = list_entry(next, struct btrfs_root, dirty_list);
1002
1003                 if (root != fs_info->extent_root)
1004                         list_add_tail(&root->dirty_list,
1005                                       &trans->transaction->switch_commits);
1006                 ret = update_cowonly_root(trans, root);
1007                 if (ret)
1008                         return ret;
1009         }
1010
1011         list_add_tail(&fs_info->extent_root->dirty_list,
1012                       &trans->transaction->switch_commits);
1013         btrfs_after_dev_replace_commit(fs_info);
1014
1015         return 0;
1016 }
1017
1018 /*
1019  * dead roots are old snapshots that need to be deleted.  This allocates
1020  * a dirty root struct and adds it into the list of dead roots that need to
1021  * be deleted
1022  */
1023 void btrfs_add_dead_root(struct btrfs_root *root)
1024 {
1025         spin_lock(&root->fs_info->trans_lock);
1026         if (list_empty(&root->root_list))
1027                 list_add_tail(&root->root_list, &root->fs_info->dead_roots);
1028         spin_unlock(&root->fs_info->trans_lock);
1029 }
1030
1031 /*
1032  * update all the cowonly tree roots on disk
1033  */
1034 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
1035                                     struct btrfs_root *root)
1036 {
1037         struct btrfs_root *gang[8];
1038         struct btrfs_fs_info *fs_info = root->fs_info;
1039         int i;
1040         int ret;
1041         int err = 0;
1042
1043         spin_lock(&fs_info->fs_roots_radix_lock);
1044         while (1) {
1045                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
1046                                                  (void **)gang, 0,
1047                                                  ARRAY_SIZE(gang),
1048                                                  BTRFS_ROOT_TRANS_TAG);
1049                 if (ret == 0)
1050                         break;
1051                 for (i = 0; i < ret; i++) {
1052                         root = gang[i];
1053                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
1054                                         (unsigned long)root->root_key.objectid,
1055                                         BTRFS_ROOT_TRANS_TAG);
1056                         spin_unlock(&fs_info->fs_roots_radix_lock);
1057
1058                         btrfs_free_log(trans, root);
1059                         btrfs_update_reloc_root(trans, root);
1060                         btrfs_orphan_commit_root(trans, root);
1061
1062                         btrfs_save_ino_cache(root, trans);
1063
1064                         /* see comments in should_cow_block() */
1065                         clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1066                         smp_mb__after_atomic();
1067
1068                         if (root->commit_root != root->node) {
1069                                 list_add_tail(&root->dirty_list,
1070                                         &trans->transaction->switch_commits);
1071                                 btrfs_set_root_node(&root->root_item,
1072                                                     root->node);
1073                         }
1074
1075                         err = btrfs_update_root(trans, fs_info->tree_root,
1076                                                 &root->root_key,
1077                                                 &root->root_item);
1078                         spin_lock(&fs_info->fs_roots_radix_lock);
1079                         if (err)
1080                                 break;
1081                 }
1082         }
1083         spin_unlock(&fs_info->fs_roots_radix_lock);
1084         return err;
1085 }
1086
1087 /*
1088  * defrag a given btree.
1089  * Every leaf in the btree is read and defragged.
1090  */
1091 int btrfs_defrag_root(struct btrfs_root *root)
1092 {
1093         struct btrfs_fs_info *info = root->fs_info;
1094         struct btrfs_trans_handle *trans;
1095         int ret;
1096
1097         if (test_and_set_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state))
1098                 return 0;
1099
1100         while (1) {
1101                 trans = btrfs_start_transaction(root, 0);
1102                 if (IS_ERR(trans))
1103                         return PTR_ERR(trans);
1104
1105                 ret = btrfs_defrag_leaves(trans, root);
1106
1107                 btrfs_end_transaction(trans, root);
1108                 btrfs_btree_balance_dirty(info->tree_root);
1109                 cond_resched();
1110
1111                 if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
1112                         break;
1113
1114                 if (btrfs_defrag_cancelled(root->fs_info)) {
1115                         pr_debug("BTRFS: defrag_root cancelled\n");
1116                         ret = -EAGAIN;
1117                         break;
1118                 }
1119         }
1120         clear_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state);
1121         return ret;
1122 }
1123
1124 /*
1125  * new snapshots need to be created at a very specific time in the
1126  * transaction commit.  This does the actual creation.
1127  *
1128  * Note:
1129  * If the error which may affect the commitment of the current transaction
1130  * happens, we should return the error number. If the error which just affect
1131  * the creation of the pending snapshots, just return 0.
1132  */
1133 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
1134                                    struct btrfs_fs_info *fs_info,
1135                                    struct btrfs_pending_snapshot *pending)
1136 {
1137         struct btrfs_key key;
1138         struct btrfs_root_item *new_root_item;
1139         struct btrfs_root *tree_root = fs_info->tree_root;
1140         struct btrfs_root *root = pending->root;
1141         struct btrfs_root *parent_root;
1142         struct btrfs_block_rsv *rsv;
1143         struct inode *parent_inode;
1144         struct btrfs_path *path;
1145         struct btrfs_dir_item *dir_item;
1146         struct dentry *dentry;
1147         struct extent_buffer *tmp;
1148         struct extent_buffer *old;
1149         struct timespec cur_time = CURRENT_TIME;
1150         int ret = 0;
1151         u64 to_reserve = 0;
1152         u64 index = 0;
1153         u64 objectid;
1154         u64 root_flags;
1155         uuid_le new_uuid;
1156
1157         path = btrfs_alloc_path();
1158         if (!path) {
1159                 pending->error = -ENOMEM;
1160                 return 0;
1161         }
1162
1163         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
1164         if (!new_root_item) {
1165                 pending->error = -ENOMEM;
1166                 goto root_item_alloc_fail;
1167         }
1168
1169         pending->error = btrfs_find_free_objectid(tree_root, &objectid);
1170         if (pending->error)
1171                 goto no_free_objectid;
1172
1173         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
1174
1175         if (to_reserve > 0) {
1176                 pending->error = btrfs_block_rsv_add(root,
1177                                                      &pending->block_rsv,
1178                                                      to_reserve,
1179                                                      BTRFS_RESERVE_NO_FLUSH);
1180                 if (pending->error)
1181                         goto no_free_objectid;
1182         }
1183
1184         key.objectid = objectid;
1185         key.offset = (u64)-1;
1186         key.type = BTRFS_ROOT_ITEM_KEY;
1187
1188         rsv = trans->block_rsv;
1189         trans->block_rsv = &pending->block_rsv;
1190         trans->bytes_reserved = trans->block_rsv->reserved;
1191
1192         dentry = pending->dentry;
1193         parent_inode = pending->dir;
1194         parent_root = BTRFS_I(parent_inode)->root;
1195         record_root_in_trans(trans, parent_root);
1196
1197         /*
1198          * insert the directory item
1199          */
1200         ret = btrfs_set_inode_index(parent_inode, &index);
1201         BUG_ON(ret); /* -ENOMEM */
1202
1203         /* check if there is a file/dir which has the same name. */
1204         dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1205                                          btrfs_ino(parent_inode),
1206                                          dentry->d_name.name,
1207                                          dentry->d_name.len, 0);
1208         if (dir_item != NULL && !IS_ERR(dir_item)) {
1209                 pending->error = -EEXIST;
1210                 goto dir_item_existed;
1211         } else if (IS_ERR(dir_item)) {
1212                 ret = PTR_ERR(dir_item);
1213                 btrfs_abort_transaction(trans, root, ret);
1214                 goto fail;
1215         }
1216         btrfs_release_path(path);
1217
1218         /*
1219          * pull in the delayed directory update
1220          * and the delayed inode item
1221          * otherwise we corrupt the FS during
1222          * snapshot
1223          */
1224         ret = btrfs_run_delayed_items(trans, root);
1225         if (ret) {      /* Transaction aborted */
1226                 btrfs_abort_transaction(trans, root, ret);
1227                 goto fail;
1228         }
1229
1230         record_root_in_trans(trans, root);
1231         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1232         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1233         btrfs_check_and_init_root_item(new_root_item);
1234
1235         root_flags = btrfs_root_flags(new_root_item);
1236         if (pending->readonly)
1237                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1238         else
1239                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1240         btrfs_set_root_flags(new_root_item, root_flags);
1241
1242         btrfs_set_root_generation_v2(new_root_item,
1243                         trans->transid);
1244         uuid_le_gen(&new_uuid);
1245         memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
1246         memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1247                         BTRFS_UUID_SIZE);
1248         if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
1249                 memset(new_root_item->received_uuid, 0,
1250                        sizeof(new_root_item->received_uuid));
1251                 memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1252                 memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1253                 btrfs_set_root_stransid(new_root_item, 0);
1254                 btrfs_set_root_rtransid(new_root_item, 0);
1255         }
1256         btrfs_set_stack_timespec_sec(&new_root_item->otime, cur_time.tv_sec);
1257         btrfs_set_stack_timespec_nsec(&new_root_item->otime, cur_time.tv_nsec);
1258         btrfs_set_root_otransid(new_root_item, trans->transid);
1259
1260         old = btrfs_lock_root_node(root);
1261         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1262         if (ret) {
1263                 btrfs_tree_unlock(old);
1264                 free_extent_buffer(old);
1265                 btrfs_abort_transaction(trans, root, ret);
1266                 goto fail;
1267         }
1268
1269         btrfs_set_lock_blocking(old);
1270
1271         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1272         /* clean up in any case */
1273         btrfs_tree_unlock(old);
1274         free_extent_buffer(old);
1275         if (ret) {
1276                 btrfs_abort_transaction(trans, root, ret);
1277                 goto fail;
1278         }
1279
1280         /*
1281          * We need to flush delayed refs in order to make sure all of our quota
1282          * operations have been done before we call btrfs_qgroup_inherit.
1283          */
1284         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1285         if (ret) {
1286                 btrfs_abort_transaction(trans, root, ret);
1287                 goto fail;
1288         }
1289
1290         ret = btrfs_qgroup_inherit(trans, fs_info,
1291                                    root->root_key.objectid,
1292                                    objectid, pending->inherit);
1293         if (ret) {
1294                 btrfs_abort_transaction(trans, root, ret);
1295                 goto fail;
1296         }
1297
1298         /* see comments in should_cow_block() */
1299         set_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1300         smp_wmb();
1301
1302         btrfs_set_root_node(new_root_item, tmp);
1303         /* record when the snapshot was created in key.offset */
1304         key.offset = trans->transid;
1305         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1306         btrfs_tree_unlock(tmp);
1307         free_extent_buffer(tmp);
1308         if (ret) {
1309                 btrfs_abort_transaction(trans, root, ret);
1310                 goto fail;
1311         }
1312
1313         /*
1314          * insert root back/forward references
1315          */
1316         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1317                                  parent_root->root_key.objectid,
1318                                  btrfs_ino(parent_inode), index,
1319                                  dentry->d_name.name, dentry->d_name.len);
1320         if (ret) {
1321                 btrfs_abort_transaction(trans, root, ret);
1322                 goto fail;
1323         }
1324
1325         key.offset = (u64)-1;
1326         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1327         if (IS_ERR(pending->snap)) {
1328                 ret = PTR_ERR(pending->snap);
1329                 btrfs_abort_transaction(trans, root, ret);
1330                 goto fail;
1331         }
1332
1333         ret = btrfs_reloc_post_snapshot(trans, pending);
1334         if (ret) {
1335                 btrfs_abort_transaction(trans, root, ret);
1336                 goto fail;
1337         }
1338
1339         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1340         if (ret) {
1341                 btrfs_abort_transaction(trans, root, ret);
1342                 goto fail;
1343         }
1344
1345         ret = btrfs_insert_dir_item(trans, parent_root,
1346                                     dentry->d_name.name, dentry->d_name.len,
1347                                     parent_inode, &key,
1348                                     BTRFS_FT_DIR, index);
1349         /* We have check then name at the beginning, so it is impossible. */
1350         BUG_ON(ret == -EEXIST || ret == -EOVERFLOW);
1351         if (ret) {
1352                 btrfs_abort_transaction(trans, root, ret);
1353                 goto fail;
1354         }
1355
1356         btrfs_i_size_write(parent_inode, parent_inode->i_size +
1357                                          dentry->d_name.len * 2);
1358         parent_inode->i_mtime = parent_inode->i_ctime = CURRENT_TIME;
1359         ret = btrfs_update_inode_fallback(trans, parent_root, parent_inode);
1360         if (ret) {
1361                 btrfs_abort_transaction(trans, root, ret);
1362                 goto fail;
1363         }
1364         ret = btrfs_uuid_tree_add(trans, fs_info->uuid_root, new_uuid.b,
1365                                   BTRFS_UUID_KEY_SUBVOL, objectid);
1366         if (ret) {
1367                 btrfs_abort_transaction(trans, root, ret);
1368                 goto fail;
1369         }
1370         if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
1371                 ret = btrfs_uuid_tree_add(trans, fs_info->uuid_root,
1372                                           new_root_item->received_uuid,
1373                                           BTRFS_UUID_KEY_RECEIVED_SUBVOL,
1374                                           objectid);
1375                 if (ret && ret != -EEXIST) {
1376                         btrfs_abort_transaction(trans, root, ret);
1377                         goto fail;
1378                 }
1379         }
1380 fail:
1381         pending->error = ret;
1382 dir_item_existed:
1383         trans->block_rsv = rsv;
1384         trans->bytes_reserved = 0;
1385 no_free_objectid:
1386         kfree(new_root_item);
1387 root_item_alloc_fail:
1388         btrfs_free_path(path);
1389         return ret;
1390 }
1391
1392 /*
1393  * create all the snapshots we've scheduled for creation
1394  */
1395 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1396                                              struct btrfs_fs_info *fs_info)
1397 {
1398         struct btrfs_pending_snapshot *pending, *next;
1399         struct list_head *head = &trans->transaction->pending_snapshots;
1400         int ret = 0;
1401
1402         list_for_each_entry_safe(pending, next, head, list) {
1403                 list_del(&pending->list);
1404                 ret = create_pending_snapshot(trans, fs_info, pending);
1405                 if (ret)
1406                         break;
1407         }
1408         return ret;
1409 }
1410
1411 static void update_super_roots(struct btrfs_root *root)
1412 {
1413         struct btrfs_root_item *root_item;
1414         struct btrfs_super_block *super;
1415
1416         super = root->fs_info->super_copy;
1417
1418         root_item = &root->fs_info->chunk_root->root_item;
1419         super->chunk_root = root_item->bytenr;
1420         super->chunk_root_generation = root_item->generation;
1421         super->chunk_root_level = root_item->level;
1422
1423         root_item = &root->fs_info->tree_root->root_item;
1424         super->root = root_item->bytenr;
1425         super->generation = root_item->generation;
1426         super->root_level = root_item->level;
1427         if (btrfs_test_opt(root, SPACE_CACHE))
1428                 super->cache_generation = root_item->generation;
1429         if (root->fs_info->update_uuid_tree_gen)
1430                 super->uuid_tree_generation = root_item->generation;
1431 }
1432
1433 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1434 {
1435         struct btrfs_transaction *trans;
1436         int ret = 0;
1437
1438         spin_lock(&info->trans_lock);
1439         trans = info->running_transaction;
1440         if (trans)
1441                 ret = (trans->state >= TRANS_STATE_COMMIT_START);
1442         spin_unlock(&info->trans_lock);
1443         return ret;
1444 }
1445
1446 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1447 {
1448         struct btrfs_transaction *trans;
1449         int ret = 0;
1450
1451         spin_lock(&info->trans_lock);
1452         trans = info->running_transaction;
1453         if (trans)
1454                 ret = is_transaction_blocked(trans);
1455         spin_unlock(&info->trans_lock);
1456         return ret;
1457 }
1458
1459 /*
1460  * wait for the current transaction commit to start and block subsequent
1461  * transaction joins
1462  */
1463 static void wait_current_trans_commit_start(struct btrfs_root *root,
1464                                             struct btrfs_transaction *trans)
1465 {
1466         wait_event(root->fs_info->transaction_blocked_wait,
1467                    trans->state >= TRANS_STATE_COMMIT_START ||
1468                    trans->aborted);
1469 }
1470
1471 /*
1472  * wait for the current transaction to start and then become unblocked.
1473  * caller holds ref.
1474  */
1475 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1476                                          struct btrfs_transaction *trans)
1477 {
1478         wait_event(root->fs_info->transaction_wait,
1479                    trans->state >= TRANS_STATE_UNBLOCKED ||
1480                    trans->aborted);
1481 }
1482
1483 /*
1484  * commit transactions asynchronously. once btrfs_commit_transaction_async
1485  * returns, any subsequent transaction will not be allowed to join.
1486  */
1487 struct btrfs_async_commit {
1488         struct btrfs_trans_handle *newtrans;
1489         struct btrfs_root *root;
1490         struct work_struct work;
1491 };
1492
1493 static void do_async_commit(struct work_struct *work)
1494 {
1495         struct btrfs_async_commit *ac =
1496                 container_of(work, struct btrfs_async_commit, work);
1497
1498         /*
1499          * We've got freeze protection passed with the transaction.
1500          * Tell lockdep about it.
1501          */
1502         if (ac->newtrans->type & __TRANS_FREEZABLE)
1503                 rwsem_acquire_read(
1504                      &ac->root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1505                      0, 1, _THIS_IP_);
1506
1507         current->journal_info = ac->newtrans;
1508
1509         btrfs_commit_transaction(ac->newtrans, ac->root);
1510         kfree(ac);
1511 }
1512
1513 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1514                                    struct btrfs_root *root,
1515                                    int wait_for_unblock)
1516 {
1517         struct btrfs_async_commit *ac;
1518         struct btrfs_transaction *cur_trans;
1519
1520         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1521         if (!ac)
1522                 return -ENOMEM;
1523
1524         INIT_WORK(&ac->work, do_async_commit);
1525         ac->root = root;
1526         ac->newtrans = btrfs_join_transaction(root);
1527         if (IS_ERR(ac->newtrans)) {
1528                 int err = PTR_ERR(ac->newtrans);
1529                 kfree(ac);
1530                 return err;
1531         }
1532
1533         /* take transaction reference */
1534         cur_trans = trans->transaction;
1535         atomic_inc(&cur_trans->use_count);
1536
1537         btrfs_end_transaction(trans, root);
1538
1539         /*
1540          * Tell lockdep we've released the freeze rwsem, since the
1541          * async commit thread will be the one to unlock it.
1542          */
1543         if (ac->newtrans->type & __TRANS_FREEZABLE)
1544                 rwsem_release(
1545                         &root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1546                         1, _THIS_IP_);
1547
1548         schedule_work(&ac->work);
1549
1550         /* wait for transaction to start and unblock */
1551         if (wait_for_unblock)
1552                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1553         else
1554                 wait_current_trans_commit_start(root, cur_trans);
1555
1556         if (current->journal_info == trans)
1557                 current->journal_info = NULL;
1558
1559         btrfs_put_transaction(cur_trans);
1560         return 0;
1561 }
1562
1563
1564 static void cleanup_transaction(struct btrfs_trans_handle *trans,
1565                                 struct btrfs_root *root, int err)
1566 {
1567         struct btrfs_transaction *cur_trans = trans->transaction;
1568         DEFINE_WAIT(wait);
1569
1570         WARN_ON(trans->use_count > 1);
1571
1572         btrfs_abort_transaction(trans, root, err);
1573
1574         spin_lock(&root->fs_info->trans_lock);
1575
1576         /*
1577          * If the transaction is removed from the list, it means this
1578          * transaction has been committed successfully, so it is impossible
1579          * to call the cleanup function.
1580          */
1581         BUG_ON(list_empty(&cur_trans->list));
1582
1583         list_del_init(&cur_trans->list);
1584         if (cur_trans == root->fs_info->running_transaction) {
1585                 cur_trans->state = TRANS_STATE_COMMIT_DOING;
1586                 spin_unlock(&root->fs_info->trans_lock);
1587                 wait_event(cur_trans->writer_wait,
1588                            atomic_read(&cur_trans->num_writers) == 1);
1589
1590                 spin_lock(&root->fs_info->trans_lock);
1591         }
1592         spin_unlock(&root->fs_info->trans_lock);
1593
1594         btrfs_cleanup_one_transaction(trans->transaction, root);
1595
1596         spin_lock(&root->fs_info->trans_lock);
1597         if (cur_trans == root->fs_info->running_transaction)
1598                 root->fs_info->running_transaction = NULL;
1599         spin_unlock(&root->fs_info->trans_lock);
1600
1601         if (trans->type & __TRANS_FREEZABLE)
1602                 sb_end_intwrite(root->fs_info->sb);
1603         btrfs_put_transaction(cur_trans);
1604         btrfs_put_transaction(cur_trans);
1605
1606         trace_btrfs_transaction_commit(root);
1607
1608         if (current->journal_info == trans)
1609                 current->journal_info = NULL;
1610         btrfs_scrub_cancel(root->fs_info);
1611
1612         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1613 }
1614
1615 static int btrfs_flush_all_pending_stuffs(struct btrfs_trans_handle *trans,
1616                                           struct btrfs_root *root)
1617 {
1618         int ret;
1619
1620         ret = btrfs_run_delayed_items(trans, root);
1621         if (ret)
1622                 return ret;
1623
1624         /*
1625          * rename don't use btrfs_join_transaction, so, once we
1626          * set the transaction to blocked above, we aren't going
1627          * to get any new ordered operations.  We can safely run
1628          * it here and no for sure that nothing new will be added
1629          * to the list
1630          */
1631         ret = btrfs_run_ordered_operations(trans, root, 1);
1632
1633         return ret;
1634 }
1635
1636 static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)
1637 {
1638         if (btrfs_test_opt(fs_info->tree_root, FLUSHONCOMMIT))
1639                 return btrfs_start_delalloc_roots(fs_info, 1, -1);
1640         return 0;
1641 }
1642
1643 static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
1644 {
1645         if (btrfs_test_opt(fs_info->tree_root, FLUSHONCOMMIT))
1646                 btrfs_wait_ordered_roots(fs_info, -1);
1647 }
1648
1649 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1650                              struct btrfs_root *root)
1651 {
1652         struct btrfs_transaction *cur_trans = trans->transaction;
1653         struct btrfs_transaction *prev_trans = NULL;
1654         int ret;
1655
1656         ret = btrfs_run_ordered_operations(trans, root, 0);
1657         if (ret) {
1658                 btrfs_abort_transaction(trans, root, ret);
1659                 btrfs_end_transaction(trans, root);
1660                 return ret;
1661         }
1662
1663         /* Stop the commit early if ->aborted is set */
1664         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1665                 ret = cur_trans->aborted;
1666                 btrfs_end_transaction(trans, root);
1667                 return ret;
1668         }
1669
1670         /* make a pass through all the delayed refs we have so far
1671          * any runnings procs may add more while we are here
1672          */
1673         ret = btrfs_run_delayed_refs(trans, root, 0);
1674         if (ret) {
1675                 btrfs_end_transaction(trans, root);
1676                 return ret;
1677         }
1678
1679         btrfs_trans_release_metadata(trans, root);
1680         trans->block_rsv = NULL;
1681         if (trans->qgroup_reserved) {
1682                 btrfs_qgroup_free(root, trans->qgroup_reserved);
1683                 trans->qgroup_reserved = 0;
1684         }
1685
1686         cur_trans = trans->transaction;
1687
1688         /*
1689          * set the flushing flag so procs in this transaction have to
1690          * start sending their work down.
1691          */
1692         cur_trans->delayed_refs.flushing = 1;
1693         smp_wmb();
1694
1695         if (!list_empty(&trans->new_bgs))
1696                 btrfs_create_pending_block_groups(trans, root);
1697
1698         ret = btrfs_run_delayed_refs(trans, root, 0);
1699         if (ret) {
1700                 btrfs_end_transaction(trans, root);
1701                 return ret;
1702         }
1703
1704         spin_lock(&root->fs_info->trans_lock);
1705         if (cur_trans->state >= TRANS_STATE_COMMIT_START) {
1706                 spin_unlock(&root->fs_info->trans_lock);
1707                 atomic_inc(&cur_trans->use_count);
1708                 ret = btrfs_end_transaction(trans, root);
1709
1710                 wait_for_commit(root, cur_trans);
1711
1712                 btrfs_put_transaction(cur_trans);
1713
1714                 return ret;
1715         }
1716
1717         cur_trans->state = TRANS_STATE_COMMIT_START;
1718         wake_up(&root->fs_info->transaction_blocked_wait);
1719
1720         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1721                 prev_trans = list_entry(cur_trans->list.prev,
1722                                         struct btrfs_transaction, list);
1723                 if (prev_trans->state != TRANS_STATE_COMPLETED) {
1724                         atomic_inc(&prev_trans->use_count);
1725                         spin_unlock(&root->fs_info->trans_lock);
1726
1727                         wait_for_commit(root, prev_trans);
1728
1729                         btrfs_put_transaction(prev_trans);
1730                 } else {
1731                         spin_unlock(&root->fs_info->trans_lock);
1732                 }
1733         } else {
1734                 spin_unlock(&root->fs_info->trans_lock);
1735         }
1736
1737         extwriter_counter_dec(cur_trans, trans->type);
1738
1739         ret = btrfs_start_delalloc_flush(root->fs_info);
1740         if (ret)
1741                 goto cleanup_transaction;
1742
1743         ret = btrfs_flush_all_pending_stuffs(trans, root);
1744         if (ret)
1745                 goto cleanup_transaction;
1746
1747         wait_event(cur_trans->writer_wait,
1748                    extwriter_counter_read(cur_trans) == 0);
1749
1750         /* some pending stuffs might be added after the previous flush. */
1751         ret = btrfs_flush_all_pending_stuffs(trans, root);
1752         if (ret)
1753                 goto cleanup_transaction;
1754
1755         btrfs_wait_delalloc_flush(root->fs_info);
1756
1757         btrfs_scrub_pause(root);
1758         /*
1759          * Ok now we need to make sure to block out any other joins while we
1760          * commit the transaction.  We could have started a join before setting
1761          * COMMIT_DOING so make sure to wait for num_writers to == 1 again.
1762          */
1763         spin_lock(&root->fs_info->trans_lock);
1764         cur_trans->state = TRANS_STATE_COMMIT_DOING;
1765         spin_unlock(&root->fs_info->trans_lock);
1766         wait_event(cur_trans->writer_wait,
1767                    atomic_read(&cur_trans->num_writers) == 1);
1768
1769         /* ->aborted might be set after the previous check, so check it */
1770         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1771                 ret = cur_trans->aborted;
1772                 goto scrub_continue;
1773         }
1774         /*
1775          * the reloc mutex makes sure that we stop
1776          * the balancing code from coming in and moving
1777          * extents around in the middle of the commit
1778          */
1779         mutex_lock(&root->fs_info->reloc_mutex);
1780
1781         /*
1782          * We needn't worry about the delayed items because we will
1783          * deal with them in create_pending_snapshot(), which is the
1784          * core function of the snapshot creation.
1785          */
1786         ret = create_pending_snapshots(trans, root->fs_info);
1787         if (ret) {
1788                 mutex_unlock(&root->fs_info->reloc_mutex);
1789                 goto scrub_continue;
1790         }
1791
1792         /*
1793          * We insert the dir indexes of the snapshots and update the inode
1794          * of the snapshots' parents after the snapshot creation, so there
1795          * are some delayed items which are not dealt with. Now deal with
1796          * them.
1797          *
1798          * We needn't worry that this operation will corrupt the snapshots,
1799          * because all the tree which are snapshoted will be forced to COW
1800          * the nodes and leaves.
1801          */
1802         ret = btrfs_run_delayed_items(trans, root);
1803         if (ret) {
1804                 mutex_unlock(&root->fs_info->reloc_mutex);
1805                 goto scrub_continue;
1806         }
1807
1808         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1809         if (ret) {
1810                 mutex_unlock(&root->fs_info->reloc_mutex);
1811                 goto scrub_continue;
1812         }
1813
1814         /*
1815          * make sure none of the code above managed to slip in a
1816          * delayed item
1817          */
1818         btrfs_assert_delayed_root_empty(root);
1819
1820         WARN_ON(cur_trans != trans->transaction);
1821
1822         /* btrfs_commit_tree_roots is responsible for getting the
1823          * various roots consistent with each other.  Every pointer
1824          * in the tree of tree roots has to point to the most up to date
1825          * root for every subvolume and other tree.  So, we have to keep
1826          * the tree logging code from jumping in and changing any
1827          * of the trees.
1828          *
1829          * At this point in the commit, there can't be any tree-log
1830          * writers, but a little lower down we drop the trans mutex
1831          * and let new people in.  By holding the tree_log_mutex
1832          * from now until after the super is written, we avoid races
1833          * with the tree-log code.
1834          */
1835         mutex_lock(&root->fs_info->tree_log_mutex);
1836
1837         ret = commit_fs_roots(trans, root);
1838         if (ret) {
1839                 mutex_unlock(&root->fs_info->tree_log_mutex);
1840                 mutex_unlock(&root->fs_info->reloc_mutex);
1841                 goto scrub_continue;
1842         }
1843
1844         /*
1845          * Since the transaction is done, we should set the inode map cache flag
1846          * before any other comming transaction.
1847          */
1848         if (btrfs_test_opt(root, CHANGE_INODE_CACHE))
1849                 btrfs_set_opt(root->fs_info->mount_opt, INODE_MAP_CACHE);
1850         else
1851                 btrfs_clear_opt(root->fs_info->mount_opt, INODE_MAP_CACHE);
1852
1853         /* commit_fs_roots gets rid of all the tree log roots, it is now
1854          * safe to free the root of tree log roots
1855          */
1856         btrfs_free_log_root_tree(trans, root->fs_info);
1857
1858         ret = commit_cowonly_roots(trans, root);
1859         if (ret) {
1860                 mutex_unlock(&root->fs_info->tree_log_mutex);
1861                 mutex_unlock(&root->fs_info->reloc_mutex);
1862                 goto scrub_continue;
1863         }
1864
1865         /*
1866          * The tasks which save the space cache and inode cache may also
1867          * update ->aborted, check it.
1868          */
1869         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1870                 ret = cur_trans->aborted;
1871                 mutex_unlock(&root->fs_info->tree_log_mutex);
1872                 mutex_unlock(&root->fs_info->reloc_mutex);
1873                 goto scrub_continue;
1874         }
1875
1876         btrfs_prepare_extent_commit(trans, root);
1877
1878         cur_trans = root->fs_info->running_transaction;
1879
1880         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1881                             root->fs_info->tree_root->node);
1882         list_add_tail(&root->fs_info->tree_root->dirty_list,
1883                       &cur_trans->switch_commits);
1884
1885         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1886                             root->fs_info->chunk_root->node);
1887         list_add_tail(&root->fs_info->chunk_root->dirty_list,
1888                       &cur_trans->switch_commits);
1889
1890         switch_commit_roots(cur_trans, root->fs_info);
1891
1892         assert_qgroups_uptodate(trans);
1893         update_super_roots(root);
1894
1895         btrfs_set_super_log_root(root->fs_info->super_copy, 0);
1896         btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
1897         memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
1898                sizeof(*root->fs_info->super_copy));
1899
1900         spin_lock(&root->fs_info->trans_lock);
1901         cur_trans->state = TRANS_STATE_UNBLOCKED;
1902         root->fs_info->running_transaction = NULL;
1903         spin_unlock(&root->fs_info->trans_lock);
1904         mutex_unlock(&root->fs_info->reloc_mutex);
1905
1906         wake_up(&root->fs_info->transaction_wait);
1907
1908         ret = btrfs_write_and_wait_transaction(trans, root);
1909         if (ret) {
1910                 btrfs_error(root->fs_info, ret,
1911                             "Error while writing out transaction");
1912                 mutex_unlock(&root->fs_info->tree_log_mutex);
1913                 goto scrub_continue;
1914         }
1915
1916         ret = write_ctree_super(trans, root, 0);
1917         if (ret) {
1918                 mutex_unlock(&root->fs_info->tree_log_mutex);
1919                 goto scrub_continue;
1920         }
1921
1922         /*
1923          * the super is written, we can safely allow the tree-loggers
1924          * to go about their business
1925          */
1926         mutex_unlock(&root->fs_info->tree_log_mutex);
1927
1928         btrfs_finish_extent_commit(trans, root);
1929
1930         root->fs_info->last_trans_committed = cur_trans->transid;
1931         /*
1932          * We needn't acquire the lock here because there is no other task
1933          * which can change it.
1934          */
1935         cur_trans->state = TRANS_STATE_COMPLETED;
1936         wake_up(&cur_trans->commit_wait);
1937
1938         spin_lock(&root->fs_info->trans_lock);
1939         list_del_init(&cur_trans->list);
1940         spin_unlock(&root->fs_info->trans_lock);
1941
1942         btrfs_put_transaction(cur_trans);
1943         btrfs_put_transaction(cur_trans);
1944
1945         if (trans->type & __TRANS_FREEZABLE)
1946                 sb_end_intwrite(root->fs_info->sb);
1947
1948         trace_btrfs_transaction_commit(root);
1949
1950         btrfs_scrub_continue(root);
1951
1952         if (current->journal_info == trans)
1953                 current->journal_info = NULL;
1954
1955         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1956
1957         if (current != root->fs_info->transaction_kthread)
1958                 btrfs_run_delayed_iputs(root);
1959
1960         return ret;
1961
1962 scrub_continue:
1963         btrfs_scrub_continue(root);
1964 cleanup_transaction:
1965         btrfs_trans_release_metadata(trans, root);
1966         trans->block_rsv = NULL;
1967         if (trans->qgroup_reserved) {
1968                 btrfs_qgroup_free(root, trans->qgroup_reserved);
1969                 trans->qgroup_reserved = 0;
1970         }
1971         btrfs_warn(root->fs_info, "Skipping commit of aborted transaction.");
1972         if (current->journal_info == trans)
1973                 current->journal_info = NULL;
1974         cleanup_transaction(trans, root, ret);
1975
1976         return ret;
1977 }
1978
1979 /*
1980  * return < 0 if error
1981  * 0 if there are no more dead_roots at the time of call
1982  * 1 there are more to be processed, call me again
1983  *
1984  * The return value indicates there are certainly more snapshots to delete, but
1985  * if there comes a new one during processing, it may return 0. We don't mind,
1986  * because btrfs_commit_super will poke cleaner thread and it will process it a
1987  * few seconds later.
1988  */
1989 int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root)
1990 {
1991         int ret;
1992         struct btrfs_fs_info *fs_info = root->fs_info;
1993
1994         spin_lock(&fs_info->trans_lock);
1995         if (list_empty(&fs_info->dead_roots)) {
1996                 spin_unlock(&fs_info->trans_lock);
1997                 return 0;
1998         }
1999         root = list_first_entry(&fs_info->dead_roots,
2000                         struct btrfs_root, root_list);
2001         list_del_init(&root->root_list);
2002         spin_unlock(&fs_info->trans_lock);
2003
2004         pr_debug("BTRFS: cleaner removing %llu\n", root->objectid);
2005
2006         btrfs_kill_all_delayed_nodes(root);
2007
2008         if (btrfs_header_backref_rev(root->node) <
2009                         BTRFS_MIXED_BACKREF_REV)
2010                 ret = btrfs_drop_snapshot(root, NULL, 0, 0);
2011         else
2012                 ret = btrfs_drop_snapshot(root, NULL, 1, 0);
2013         /*
2014          * If we encounter a transaction abort during snapshot cleaning, we
2015          * don't want to crash here
2016          */
2017         return (ret < 0) ? 0 : 1;
2018 }