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 void clear_btree_io_tree(struct extent_io_tree *tree)
  80 {
  81         spin_lock(&tree->lock);
  82         while (!RB_EMPTY_ROOT(&tree->state)) {
  83                 struct rb_node *node;
  84                 struct extent_state *state;
  85
  86                 node = rb_first(&tree->state);
  87                 state = rb_entry(node, struct extent_state, rb_node);
  88                 rb_erase(&state->rb_node, &tree->state);
  89                 RB_CLEAR_NODE(&state->rb_node);
  90                 /*
  91                  * btree io trees aren't supposed to have tasks waiting for
  92                  * changes in the flags of extent states ever.
  93                  */
  94                 ASSERT(!waitqueue_active(&state->wq));
  95                 free_extent_state(state);
  96                 if (need_resched()) {
  97                         spin_unlock(&tree->lock);
  98                         cond_resched();
  99                         spin_lock(&tree->lock);
 100                 }
 101         }
 102         spin_unlock(&tree->lock);
 103 }
 104
 105 static noinline void switch_commit_roots(struct btrfs_transaction *trans,
 106                                          struct btrfs_fs_info *fs_info)
 107 {
 108         struct btrfs_root *root, *tmp;
 109
 110         down_write(&fs_info->commit_root_sem);
 111         list_for_each_entry_safe(root, tmp, &trans->switch_commits,
 112                                  dirty_list) {
 113                 list_del_init(&root->dirty_list);
 114                 free_extent_buffer(root->commit_root);
 115                 root->commit_root = btrfs_root_node(root);
 116                 if (is_fstree(root->objectid))
 117                         btrfs_unpin_free_ino(root);
 118                 clear_btree_io_tree(&root->dirty_log_pages);
 119         }
 120         up_write(&fs_info->commit_root_sem);
 121 }
 122
 123 static inline void extwriter_counter_inc(struct btrfs_transaction *trans,
 124                                          unsigned int type)
 125 {
 126         if (type & TRANS_EXTWRITERS)
 127                 atomic_inc(&trans->num_extwriters);
 128 }
 129
 130 static inline void extwriter_counter_dec(struct btrfs_transaction *trans,
 131                                          unsigned int type)
 132 {
 133         if (type & TRANS_EXTWRITERS)
 134                 atomic_dec(&trans->num_extwriters);
 135 }
 136
 137 static inline void extwriter_counter_init(struct btrfs_transaction *trans,
 138                                           unsigned int type)
 139 {
 140         atomic_set(&trans->num_extwriters, ((type & TRANS_EXTWRITERS) ? 1 : 0));
 141 }
 142
 143 static inline int extwriter_counter_read(struct btrfs_transaction *trans)
 144 {
 145         return atomic_read(&trans->num_extwriters);
 146 }
 147
 148 /*
 149  * either allocate a new transaction or hop into the existing one
 150  */
 151 static noinline int join_transaction(struct btrfs_root *root, unsigned int type)
 152 {
 153         struct btrfs_transaction *cur_trans;
 154         struct btrfs_fs_info *fs_info = root->fs_info;
 155
 156         spin_lock(&fs_info->trans_lock);
 157 loop:
 158         /* The file system has been taken offline. No new transactions. */
 159         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 160                 spin_unlock(&fs_info->trans_lock);
 161                 return -EROFS;
 162         }
 163
 164         cur_trans = fs_info->running_transaction;
 165         if (cur_trans) {
 166                 if (cur_trans->aborted) {
 167                         spin_unlock(&fs_info->trans_lock);
 168                         return cur_trans->aborted;
 169                 }
 170                 if (btrfs_blocked_trans_types[cur_trans->state] & type) {
 171                         spin_unlock(&fs_info->trans_lock);
 172                         return -EBUSY;
 173                 }
 174                 atomic_inc(&cur_trans->use_count);
 175                 atomic_inc(&cur_trans->num_writers);
 176                 extwriter_counter_inc(cur_trans, type);
 177                 spin_unlock(&fs_info->trans_lock);
 178                 return 0;
 179         }
 180         spin_unlock(&fs_info->trans_lock);
 181
 182         /*
 183          * If we are ATTACH, we just want to catch the current transaction,
 184          * and commit it. If there is no transaction, just return ENOENT.
 185          */
 186         if (type == TRANS_ATTACH)
 187                 return -ENOENT;
 188
 189         /*
 190          * JOIN_NOLOCK only happens during the transaction commit, so
 191          * it is impossible that ->running_transaction is NULL
 192          */
 193         BUG_ON(type == TRANS_JOIN_NOLOCK);
 194
 195         cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
 196         if (!cur_trans)
 197                 return -ENOMEM;
 198
 199         spin_lock(&fs_info->trans_lock);
 200         if (fs_info->running_transaction) {
 201                 /*
 202                  * someone started a transaction after we unlocked.  Make sure
 203                  * to redo the checks above
 204                  */
 205                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 206                 goto loop;
 207         } else if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 208                 spin_unlock(&fs_info->trans_lock);
 209                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 210                 return -EROFS;
 211         }
 212
 213         atomic_set(&cur_trans->num_writers, 1);
 214         extwriter_counter_init(cur_trans, type);
 215         init_waitqueue_head(&cur_trans->writer_wait);
 216         init_waitqueue_head(&cur_trans->commit_wait);
 217         cur_trans->state = TRANS_STATE_RUNNING;
 218         /*
 219          * One for this trans handle, one so it will live on until we
 220          * commit the transaction.
 221          */
 222         atomic_set(&cur_trans->use_count, 2);
 223         cur_trans->start_time = get_seconds();
 224
 225         cur_trans->delayed_refs.href_root = RB_ROOT;
 226         atomic_set(&cur_trans->delayed_refs.num_entries, 0);
 227         cur_trans->delayed_refs.num_heads_ready = 0;
 228         cur_trans->delayed_refs.num_heads = 0;
 229         cur_trans->delayed_refs.flushing = 0;
 230         cur_trans->delayed_refs.run_delayed_start = 0;
 231
 232         /*
 233          * although the tree mod log is per file system and not per transaction,
 234          * the log must never go across transaction boundaries.
 235          */
 236         smp_mb();
 237         if (!list_empty(&fs_info->tree_mod_seq_list))
 238                 WARN(1, KERN_ERR "BTRFS: tree_mod_seq_list not empty when "
 239                         "creating a fresh transaction\n");
 240         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log))
 241                 WARN(1, KERN_ERR "BTRFS: tree_mod_log rb tree not empty when "
 242                         "creating a fresh transaction\n");
 243         atomic64_set(&fs_info->tree_mod_seq, 0);
 244
 245         spin_lock_init(&cur_trans->delayed_refs.lock);
 246
 247         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 248         INIT_LIST_HEAD(&cur_trans->pending_chunks);
 249         INIT_LIST_HEAD(&cur_trans->switch_commits);
 250         INIT_LIST_HEAD(&cur_trans->pending_ordered);
 251         INIT_LIST_HEAD(&cur_trans->dirty_bgs);
 252         spin_lock_init(&cur_trans->dirty_bgs_lock);
 253         list_add_tail(&cur_trans->list, &fs_info->trans_list);
 254         extent_io_tree_init(&cur_trans->dirty_pages,
 255                              fs_info->btree_inode->i_mapping);
 256         fs_info->generation++;
 257         cur_trans->transid = fs_info->generation;
 258         fs_info->running_transaction = cur_trans;
 259         cur_trans->aborted = 0;
 260         spin_unlock(&fs_info->trans_lock);
 261
 262         return 0;
 263 }
 264
 265 /*
 266  * this does all the record keeping required to make sure that a reference
 267  * counted root is properly recorded in a given transaction.  This is required
 268  * to make sure the old root from before we joined the transaction is deleted
 269  * when the transaction commits
 270  */
 271 static int record_root_in_trans(struct btrfs_trans_handle *trans,
 272                                struct btrfs_root *root)
 273 {
 274         if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
 275             root->last_trans < trans->transid) {
 276                 WARN_ON(root == root->fs_info->extent_root);
 277                 WARN_ON(root->commit_root != root->node);
 278
 279                 /*
 280                  * see below for IN_TRANS_SETUP usage rules
 281                  * we have the reloc mutex held now, so there
 282                  * is only one writer in this function
 283                  */
 284                 set_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
 285
 286                 /* make sure readers find IN_TRANS_SETUP before
 287                  * they find our root->last_trans update
 288                  */
 289                 smp_wmb();
 290
 291                 spin_lock(&root->fs_info->fs_roots_radix_lock);
 292                 if (root->last_trans == trans->transid) {
 293                         spin_unlock(&root->fs_info->fs_roots_radix_lock);
 294                         return 0;
 295                 }
 296                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 297                            (unsigned long)root->root_key.objectid,
 298                            BTRFS_ROOT_TRANS_TAG);
 299                 spin_unlock(&root->fs_info->fs_roots_radix_lock);
 300                 root->last_trans = trans->transid;
 301
 302                 /* this is pretty tricky.  We don't want to
 303                  * take the relocation lock in btrfs_record_root_in_trans
 304                  * unless we're really doing the first setup for this root in
 305                  * this transaction.
 306                  *
 307                  * Normally we'd use root->last_trans as a flag to decide
 308                  * if we want to take the expensive mutex.
 309                  *
 310                  * But, we have to set root->last_trans before we
 311                  * init the relocation root, otherwise, we trip over warnings
 312                  * in ctree.c.  The solution used here is to flag ourselves
 313                  * with root IN_TRANS_SETUP.  When this is 1, we're still
 314                  * fixing up the reloc trees and everyone must wait.
 315                  *
 316                  * When this is zero, they can trust root->last_trans and fly
 317                  * through btrfs_record_root_in_trans without having to take the
 318                  * lock.  smp_wmb() makes sure that all the writes above are
 319                  * done before we pop in the zero below
 320                  */
 321                 btrfs_init_reloc_root(trans, root);
 322                 smp_mb__before_atomic();
 323                 clear_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
 324         }
 325         return 0;
 326 }
 327
 328
 329 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 330                                struct btrfs_root *root)
 331 {
 332         if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 333                 return 0;
 334
 335         /*
 336          * see record_root_in_trans for comments about IN_TRANS_SETUP usage
 337          * and barriers
 338          */
 339         smp_rmb();
 340         if (root->last_trans == trans->transid &&
 341             !test_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state))
 342                 return 0;
 343
 344         mutex_lock(&root->fs_info->reloc_mutex);
 345         record_root_in_trans(trans, root);
 346         mutex_unlock(&root->fs_info->reloc_mutex);
 347
 348         return 0;
 349 }
 350
 351 static inline int is_transaction_blocked(struct btrfs_transaction *trans)
 352 {
 353         return (trans->state >= TRANS_STATE_BLOCKED &&
 354                 trans->state < TRANS_STATE_UNBLOCKED &&
 355                 !trans->aborted);
 356 }
 357
 358 /* wait for commit against the current transaction to become unblocked
 359  * when this is done, it is safe to start a new transaction, but the current
 360  * transaction might not be fully on disk.
 361  */
 362 static void wait_current_trans(struct btrfs_root *root)
 363 {
 364         struct btrfs_transaction *cur_trans;
 365
 366         spin_lock(&root->fs_info->trans_lock);
 367         cur_trans = root->fs_info->running_transaction;
 368         if (cur_trans && is_transaction_blocked(cur_trans)) {
 369                 atomic_inc(&cur_trans->use_count);
 370                 spin_unlock(&root->fs_info->trans_lock);
 371
 372                 wait_event(root->fs_info->transaction_wait,
 373                            cur_trans->state >= TRANS_STATE_UNBLOCKED ||
 374                            cur_trans->aborted);
 375                 btrfs_put_transaction(cur_trans);
 376         } else {
 377                 spin_unlock(&root->fs_info->trans_lock);
 378         }
 379 }
 380
 381 static int may_wait_transaction(struct btrfs_root *root, int type)
 382 {
 383         if (root->fs_info->log_root_recovering)
 384                 return 0;
 385
 386         if (type == TRANS_USERSPACE)
 387                 return 1;
 388
 389         if (type == TRANS_START &&
 390             !atomic_read(&root->fs_info->open_ioctl_trans))
 391                 return 1;
 392
 393         return 0;
 394 }
 395
 396 static inline bool need_reserve_reloc_root(struct btrfs_root *root)
 397 {
 398         if (!root->fs_info->reloc_ctl ||
 399             !test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
 400             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 401             root->reloc_root)
 402                 return false;
 403
 404         return true;
 405 }
 406
 407 static struct btrfs_trans_handle *
 408 start_transaction(struct btrfs_root *root, u64 num_items, unsigned int type,
 409                   enum btrfs_reserve_flush_enum flush)
 410 {
 411         struct btrfs_trans_handle *h;
 412         struct btrfs_transaction *cur_trans;
 413         u64 num_bytes = 0;
 414         u64 qgroup_reserved = 0;
 415         bool reloc_reserved = false;
 416         int ret;
 417
 418         /* Send isn't supposed to start transactions. */
 419         ASSERT(current->journal_info != BTRFS_SEND_TRANS_STUB);
 420
 421         if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state))
 422                 return ERR_PTR(-EROFS);
 423
 424         if (current->journal_info) {
 425                 WARN_ON(type & TRANS_EXTWRITERS);
 426                 h = current->journal_info;
 427                 h->use_count++;
 428                 WARN_ON(h->use_count > 2);
 429                 h->orig_rsv = h->block_rsv;
 430                 h->block_rsv = NULL;
 431                 goto got_it;
 432         }
 433
 434         /*
 435          * Do the reservation before we join the transaction so we can do all
 436          * the appropriate flushing if need be.
 437          */
 438         if (num_items > 0 && root != root->fs_info->chunk_root) {
 439                 if (root->fs_info->quota_enabled &&
 440                     is_fstree(root->root_key.objectid)) {
 441                         qgroup_reserved = num_items * root->nodesize;
 442                         ret = btrfs_qgroup_reserve(root, qgroup_reserved);
 443                         if (ret)
 444                                 return ERR_PTR(ret);
 445                 }
 446
 447                 num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
 448                 /*
 449                  * Do the reservation for the relocation root creation
 450                  */
 451                 if (need_reserve_reloc_root(root)) {
 452                         num_bytes += root->nodesize;
 453                         reloc_reserved = true;
 454                 }
 455
 456                 ret = btrfs_block_rsv_add(root,
 457                                           &root->fs_info->trans_block_rsv,
 458                                           num_bytes, flush);
 459                 if (ret)
 460                         goto reserve_fail;
 461         }
 462 again:
 463         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 464         if (!h) {
 465                 ret = -ENOMEM;
 466                 goto alloc_fail;
 467         }
 468
 469         /*
 470          * If we are JOIN_NOLOCK we're already committing a transaction and
 471          * waiting on this guy, so we don't need to do the sb_start_intwrite
 472          * because we're already holding a ref.  We need this because we could
 473          * have raced in and did an fsync() on a file which can kick a commit
 474          * and then we deadlock with somebody doing a freeze.
 475          *
 476          * If we are ATTACH, it means we just want to catch the current
 477          * transaction and commit it, so we needn't do sb_start_intwrite().
 478          */
 479         if (type & __TRANS_FREEZABLE)
 480                 sb_start_intwrite(root->fs_info->sb);
 481
 482         if (may_wait_transaction(root, type))
 483                 wait_current_trans(root);
 484
 485         do {
 486                 ret = join_transaction(root, type);
 487                 if (ret == -EBUSY) {
 488                         wait_current_trans(root);
 489                         if (unlikely(type == TRANS_ATTACH))
 490                                 ret = -ENOENT;
 491                 }
 492         } while (ret == -EBUSY);
 493
 494         if (ret < 0) {
 495                 /* We must get the transaction if we are JOIN_NOLOCK. */
 496                 BUG_ON(type == TRANS_JOIN_NOLOCK);
 497                 goto join_fail;
 498         }
 499
 500         cur_trans = root->fs_info->running_transaction;
 501
 502         h->transid = cur_trans->transid;
 503         h->transaction = cur_trans;
 504         h->blocks_used = 0;
 505         h->bytes_reserved = 0;
 506         h->root = root;
 507         h->delayed_ref_updates = 0;
 508         h->use_count = 1;
 509         h->adding_csums = 0;
 510         h->block_rsv = NULL;
 511         h->orig_rsv = NULL;
 512         h->aborted = 0;
 513         h->qgroup_reserved = 0;
 514         h->delayed_ref_elem.seq = 0;
 515         h->type = type;
 516         h->allocating_chunk = false;
 517         h->reloc_reserved = false;
 518         h->sync = false;
 519         INIT_LIST_HEAD(&h->qgroup_ref_list);
 520         INIT_LIST_HEAD(&h->new_bgs);
 521         INIT_LIST_HEAD(&h->ordered);
 522
 523         smp_mb();
 524         if (cur_trans->state >= TRANS_STATE_BLOCKED &&
 525             may_wait_transaction(root, type)) {
 526                 current->journal_info = h;
 527                 btrfs_commit_transaction(h, root);
 528                 goto again;
 529         }
 530
 531         if (num_bytes) {
 532                 trace_btrfs_space_reservation(root->fs_info, "transaction",
 533                                               h->transid, num_bytes, 1);
 534                 h->block_rsv = &root->fs_info->trans_block_rsv;
 535                 h->bytes_reserved = num_bytes;
 536                 h->reloc_reserved = reloc_reserved;
 537         }
 538         h->qgroup_reserved = qgroup_reserved;
 539
 540 got_it:
 541         btrfs_record_root_in_trans(h, root);
 542
 543         if (!current->journal_info && type != TRANS_USERSPACE)
 544                 current->journal_info = h;
 545         return h;
 546
 547 join_fail:
 548         if (type & __TRANS_FREEZABLE)
 549                 sb_end_intwrite(root->fs_info->sb);
 550         kmem_cache_free(btrfs_trans_handle_cachep, h);
 551 alloc_fail:
 552         if (num_bytes)
 553                 btrfs_block_rsv_release(root, &root->fs_info->trans_block_rsv,
 554                                         num_bytes);
 555 reserve_fail:
 556         if (qgroup_reserved)
 557                 btrfs_qgroup_free(root, qgroup_reserved);
 558         return ERR_PTR(ret);
 559 }
 560
 561 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 562                                                    int num_items)
 563 {
 564         return start_transaction(root, num_items, TRANS_START,
 565                                  BTRFS_RESERVE_FLUSH_ALL);
 566 }
 567
 568 struct btrfs_trans_handle *btrfs_start_transaction_lflush(
 569                                         struct btrfs_root *root, int num_items)
 570 {
 571         return start_transaction(root, num_items, TRANS_START,
 572                                  BTRFS_RESERVE_FLUSH_LIMIT);
 573 }
 574
 575 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 576 {
 577         return start_transaction(root, 0, TRANS_JOIN, 0);
 578 }
 579
 580 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
 581 {
 582         return start_transaction(root, 0, TRANS_JOIN_NOLOCK, 0);
 583 }
 584
 585 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 586 {
 587         return start_transaction(root, 0, TRANS_USERSPACE, 0);
 588 }
 589
 590 /*
 591  * btrfs_attach_transaction() - catch the running transaction
 592  *
 593  * It is used when we want to commit the current the transaction, but
 594  * don't want to start a new one.
 595  *
 596  * Note: If this function return -ENOENT, it just means there is no
 597  * running transaction. But it is possible that the inactive transaction
 598  * is still in the memory, not fully on disk. If you hope there is no
 599  * inactive transaction in the fs when -ENOENT is returned, you should
 600  * invoke
 601  *     btrfs_attach_transaction_barrier()
 602  */
 603 struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
 604 {
 605         return start_transaction(root, 0, TRANS_ATTACH, 0);
 606 }
 607
 608 /*
 609  * btrfs_attach_transaction_barrier() - catch the running transaction
 610  *
 611  * It is similar to the above function, the differentia is this one
 612  * will wait for all the inactive transactions until they fully
 613  * complete.
 614  */
 615 struct btrfs_trans_handle *
 616 btrfs_attach_transaction_barrier(struct btrfs_root *root)
 617 {
 618         struct btrfs_trans_handle *trans;
 619
 620         trans = start_transaction(root, 0, TRANS_ATTACH, 0);
 621         if (IS_ERR(trans) && PTR_ERR(trans) == -ENOENT)
 622                 btrfs_wait_for_commit(root, 0);
 623
 624         return trans;
 625 }
 626
 627 /* wait for a transaction commit to be fully complete */
 628 static noinline void wait_for_commit(struct btrfs_root *root,
 629                                     struct btrfs_transaction *commit)
 630 {
 631         wait_event(commit->commit_wait, commit->state == TRANS_STATE_COMPLETED);
 632 }
 633
 634 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 635 {
 636         struct btrfs_transaction *cur_trans = NULL, *t;
 637         int ret = 0;
 638
 639         if (transid) {
 640                 if (transid <= root->fs_info->last_trans_committed)
 641                         goto out;
 642
 643                 /* find specified transaction */
 644                 spin_lock(&root->fs_info->trans_lock);
 645                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 646                         if (t->transid == transid) {
 647                                 cur_trans = t;
 648                                 atomic_inc(&cur_trans->use_count);
 649                                 ret = 0;
 650                                 break;
 651                         }
 652                         if (t->transid > transid) {
 653                                 ret = 0;
 654                                 break;
 655                         }
 656                 }
 657                 spin_unlock(&root->fs_info->trans_lock);
 658
 659                 /*
 660                  * The specified transaction doesn't exist, or we
 661                  * raced with btrfs_commit_transaction
 662                  */
 663                 if (!cur_trans) {
 664                         if (transid > root->fs_info->last_trans_committed)
 665                                 ret = -EINVAL;
 666                         goto out;
 667                 }
 668         } else {
 669                 /* find newest transaction that is committing | committed */
 670                 spin_lock(&root->fs_info->trans_lock);
 671                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 672                                             list) {
 673                         if (t->state >= TRANS_STATE_COMMIT_START) {
 674                                 if (t->state == TRANS_STATE_COMPLETED)
 675                                         break;
 676                                 cur_trans = t;
 677                                 atomic_inc(&cur_trans->use_count);
 678                                 break;
 679                         }
 680                 }
 681                 spin_unlock(&root->fs_info->trans_lock);
 682                 if (!cur_trans)
 683                         goto out;  /* nothing committing|committed */
 684         }
 685
 686         wait_for_commit(root, cur_trans);
 687         btrfs_put_transaction(cur_trans);
 688 out:
 689         return ret;
 690 }
 691
 692 void btrfs_throttle(struct btrfs_root *root)
 693 {
 694         if (!atomic_read(&root->fs_info->open_ioctl_trans))
 695                 wait_current_trans(root);
 696 }
 697
 698 static int should_end_transaction(struct btrfs_trans_handle *trans,
 699                                   struct btrfs_root *root)
 700 {
 701         if (root->fs_info->global_block_rsv.space_info->full &&
 702             btrfs_check_space_for_delayed_refs(trans, root))
 703                 return 1;
 704
 705         return !!btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
 706 }
 707
 708 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 709                                  struct btrfs_root *root)
 710 {
 711         struct btrfs_transaction *cur_trans = trans->transaction;
 712         int updates;
 713         int err;
 714
 715         smp_mb();
 716         if (cur_trans->state >= TRANS_STATE_BLOCKED ||
 717             cur_trans->delayed_refs.flushing)
 718                 return 1;
 719
 720         updates = trans->delayed_ref_updates;
 721         trans->delayed_ref_updates = 0;
 722         if (updates) {
 723                 err = btrfs_run_delayed_refs(trans, root, updates);
 724                 if (err) /* Error code will also eval true */
 725                         return err;
 726         }
 727
 728         return should_end_transaction(trans, root);
 729 }
 730
 731 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 732                           struct btrfs_root *root, int throttle)
 733 {
 734         struct btrfs_transaction *cur_trans = trans->transaction;
 735         struct btrfs_fs_info *info = root->fs_info;
 736         unsigned long cur = trans->delayed_ref_updates;
 737         int lock = (trans->type != TRANS_JOIN_NOLOCK);
 738         int err = 0;
 739         int must_run_delayed_refs = 0;
 740
 741         if (trans->use_count > 1) {
 742                 trans->use_count--;
 743                 trans->block_rsv = trans->orig_rsv;
 744                 return 0;
 745         }
 746
 747         btrfs_trans_release_metadata(trans, root);
 748         trans->block_rsv = NULL;
 749
 750         if (!list_empty(&trans->new_bgs))
 751                 btrfs_create_pending_block_groups(trans, root);
 752
 753         if (!list_empty(&trans->ordered)) {
 754                 spin_lock(&info->trans_lock);
 755                 list_splice(&trans->ordered, &cur_trans->pending_ordered);
 756                 spin_unlock(&info->trans_lock);
 757         }
 758
 759         trans->delayed_ref_updates = 0;
 760         if (!trans->sync) {
 761                 must_run_delayed_refs =
 762                         btrfs_should_throttle_delayed_refs(trans, root);
 763                 cur = max_t(unsigned long, cur, 32);
 764
 765                 /*
 766                  * don't make the caller wait if they are from a NOLOCK
 767                  * or ATTACH transaction, it will deadlock with commit
 768                  */
 769                 if (must_run_delayed_refs == 1 &&
 770                     (trans->type & (__TRANS_JOIN_NOLOCK | __TRANS_ATTACH)))
 771                         must_run_delayed_refs = 2;
 772         }
 773
 774         if (trans->qgroup_reserved) {
 775                 /*
 776                  * the same root has to be passed here between start_transaction
 777                  * and end_transaction. Subvolume quota depends on this.
 778                  */
 779                 btrfs_qgroup_free(trans->root, trans->qgroup_reserved);
 780                 trans->qgroup_reserved = 0;
 781         }
 782
 783         btrfs_trans_release_metadata(trans, root);
 784         trans->block_rsv = NULL;
 785
 786         if (!list_empty(&trans->new_bgs))
 787                 btrfs_create_pending_block_groups(trans, root);
 788
 789         if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
 790             should_end_transaction(trans, root) &&
 791             ACCESS_ONCE(cur_trans->state) == TRANS_STATE_RUNNING) {
 792                 spin_lock(&info->trans_lock);
 793                 if (cur_trans->state == TRANS_STATE_RUNNING)
 794                         cur_trans->state = TRANS_STATE_BLOCKED;
 795                 spin_unlock(&info->trans_lock);
 796         }
 797
 798         if (lock && ACCESS_ONCE(cur_trans->state) == TRANS_STATE_BLOCKED) {
 799                 if (throttle)
 800                         return btrfs_commit_transaction(trans, root);
 801                 else
 802                         wake_up_process(info->transaction_kthread);
 803         }
 804
 805         if (trans->type & __TRANS_FREEZABLE)
 806                 sb_end_intwrite(root->fs_info->sb);
 807
 808         WARN_ON(cur_trans != info->running_transaction);
 809         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 810         atomic_dec(&cur_trans->num_writers);
 811         extwriter_counter_dec(cur_trans, trans->type);
 812
 813         smp_mb();
 814         if (waitqueue_active(&cur_trans->writer_wait))
 815                 wake_up(&cur_trans->writer_wait);
 816         btrfs_put_transaction(cur_trans);
 817
 818         if (current->journal_info == trans)
 819                 current->journal_info = NULL;
 820
 821         if (throttle)
 822                 btrfs_run_delayed_iputs(root);
 823
 824         if (trans->aborted ||
 825             test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) {
 826                 wake_up_process(info->transaction_kthread);
 827                 err = -EIO;
 828         }
 829         assert_qgroups_uptodate(trans);
 830
 831         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 832         if (must_run_delayed_refs) {
 833                 btrfs_async_run_delayed_refs(root, cur,
 834                                              must_run_delayed_refs == 1);
 835         }
 836         return err;
 837 }
 838
 839 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 840                           struct btrfs_root *root)
 841 {
 842         return __btrfs_end_transaction(trans, root, 0);
 843 }
 844
 845 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 846                                    struct btrfs_root *root)
 847 {
 848         return __btrfs_end_transaction(trans, root, 1);
 849 }
 850
 851 /*
 852  * when btree blocks are allocated, they have some corresponding bits set for
 853  * them in one of two extent_io trees.  This is used to make sure all of
 854  * those extents are sent to disk but does not wait on them
 855  */
 856 int btrfs_write_marked_extents(struct btrfs_root *root,
 857                                struct extent_io_tree *dirty_pages, int mark)
 858 {
 859         int err = 0;
 860         int werr = 0;
 861         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 862         struct extent_state *cached_state = NULL;
 863         u64 start = 0;
 864         u64 end;
 865
 866         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 867                                       mark, &cached_state)) {
 868                 bool wait_writeback = false;
 869
 870                 err = convert_extent_bit(dirty_pages, start, end,
 871                                          EXTENT_NEED_WAIT,
 872                                          mark, &cached_state, GFP_NOFS);
 873                 /*
 874                  * convert_extent_bit can return -ENOMEM, which is most of the
 875                  * time a temporary error. So when it happens, ignore the error
 876                  * and wait for writeback of this range to finish - because we
 877                  * failed to set the bit EXTENT_NEED_WAIT for the range, a call
 878                  * to btrfs_wait_marked_extents() would not know that writeback
 879                  * for this range started and therefore wouldn't wait for it to
 880                  * finish - we don't want to commit a superblock that points to
 881                  * btree nodes/leafs for which writeback hasn't finished yet
 882                  * (and without errors).
 883                  * We cleanup any entries left in the io tree when committing
 884                  * the transaction (through clear_btree_io_tree()).
 885                  */
 886                 if (err == -ENOMEM) {
 887                         err = 0;
 888                         wait_writeback = true;
 889                 }
 890                 if (!err)
 891                         err = filemap_fdatawrite_range(mapping, start, end);
 892                 if (err)
 893                         werr = err;
 894                 else if (wait_writeback)
 895                         werr = filemap_fdatawait_range(mapping, start, end);
 896                 free_extent_state(cached_state);
 897                 cached_state = NULL;
 898                 cond_resched();
 899                 start = end + 1;
 900         }
 901         return werr;
 902 }
 903
 904 /*
 905  * when btree blocks are allocated, they have some corresponding bits set for
 906  * them in one of two extent_io trees.  This is used to make sure all of
 907  * those extents are on disk for transaction or log commit.  We wait
 908  * on all the pages and clear them from the dirty pages state tree
 909  */
 910 int btrfs_wait_marked_extents(struct btrfs_root *root,
 911                               struct extent_io_tree *dirty_pages, int mark)
 912 {
 913         int err = 0;
 914         int werr = 0;
 915         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 916         struct extent_state *cached_state = NULL;
 917         u64 start = 0;
 918         u64 end;
 919         struct btrfs_inode *btree_ino = BTRFS_I(root->fs_info->btree_inode);
 920         bool errors = false;
 921
 922         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 923                                       EXTENT_NEED_WAIT, &cached_state)) {
 924                 /*
 925                  * Ignore -ENOMEM errors returned by clear_extent_bit().
 926                  * When committing the transaction, we'll remove any entries
 927                  * left in the io tree. For a log commit, we don't remove them
 928                  * after committing the log because the tree can be accessed
 929                  * concurrently - we do it only at transaction commit time when
 930                  * it's safe to do it (through clear_btree_io_tree()).
 931                  */
 932                 err = clear_extent_bit(dirty_pages, start, end,
 933                                        EXTENT_NEED_WAIT,
 934                                        0, 0, &cached_state, GFP_NOFS);
 935                 if (err == -ENOMEM)
 936                         err = 0;
 937                 if (!err)
 938                         err = filemap_fdatawait_range(mapping, start, end);
 939                 if (err)
 940                         werr = err;
 941                 free_extent_state(cached_state);
 942                 cached_state = NULL;
 943                 cond_resched();
 944                 start = end + 1;
 945         }
 946         if (err)
 947                 werr = err;
 948
 949         if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID) {
 950                 if ((mark & EXTENT_DIRTY) &&
 951                     test_and_clear_bit(BTRFS_INODE_BTREE_LOG1_ERR,
 952                                        &btree_ino->runtime_flags))
 953                         errors = true;
 954
 955                 if ((mark & EXTENT_NEW) &&
 956                     test_and_clear_bit(BTRFS_INODE_BTREE_LOG2_ERR,
 957                                        &btree_ino->runtime_flags))
 958                         errors = true;
 959         } else {
 960                 if (test_and_clear_bit(BTRFS_INODE_BTREE_ERR,
 961                                        &btree_ino->runtime_flags))
 962                         errors = true;
 963         }
 964
 965         if (errors && !werr)
 966                 werr = -EIO;
 967
 968         return werr;
 969 }
 970
 971 /*
 972  * when btree blocks are allocated, they have some corresponding bits set for
 973  * them in one of two extent_io trees.  This is used to make sure all of
 974  * those extents are on disk for transaction or log commit
 975  */
 976 static int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 977                                 struct extent_io_tree *dirty_pages, int mark)
 978 {
 979         int ret;
 980         int ret2;
 981         struct blk_plug plug;
 982
 983         blk_start_plug(&plug);
 984         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 985         blk_finish_plug(&plug);
 986         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 987
 988         if (ret)
 989                 return ret;
 990         if (ret2)
 991                 return ret2;
 992         return 0;
 993 }
 994
 995 static int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 996                                      struct btrfs_root *root)
 997 {
 998         int ret;
 999
1000         ret = btrfs_write_and_wait_marked_extents(root,
1001                                            &trans->transaction->dirty_pages,
1002                                            EXTENT_DIRTY);
1003         clear_btree_io_tree(&trans->transaction->dirty_pages);
1004
1005         return ret;
1006 }
1007
1008 /*
1009  * this is used to update the root pointer in the tree of tree roots.
1010  *
1011  * But, in the case of the extent allocation tree, updating the root
1012  * pointer may allocate blocks which may change the root of the extent
1013  * allocation tree.
1014  *
1015  * So, this loops and repeats and makes sure the cowonly root didn't
1016  * change while the root pointer was being updated in the metadata.
1017  */
1018 static int update_cowonly_root(struct btrfs_trans_handle *trans,
1019                                struct btrfs_root *root)
1020 {
1021         int ret;
1022         u64 old_root_bytenr;
1023         u64 old_root_used;
1024         struct btrfs_root *tree_root = root->fs_info->tree_root;
1025         bool extent_root = (root->objectid == BTRFS_EXTENT_TREE_OBJECTID);
1026
1027         old_root_used = btrfs_root_used(&root->root_item);
1028         btrfs_write_dirty_block_groups(trans, root);
1029
1030         while (1) {
1031                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
1032                 if (old_root_bytenr == root->node->start &&
1033                     old_root_used == btrfs_root_used(&root->root_item) &&
1034                     (!extent_root ||
1035                      list_empty(&trans->transaction->dirty_bgs)))
1036                         break;
1037
1038                 btrfs_set_root_node(&root->root_item, root->node);
1039                 ret = btrfs_update_root(trans, tree_root,
1040                                         &root->root_key,
1041                                         &root->root_item);
1042                 if (ret)
1043                         return ret;
1044
1045                 old_root_used = btrfs_root_used(&root->root_item);
1046                 if (extent_root) {
1047                         ret = btrfs_write_dirty_block_groups(trans, root);
1048                         if (ret)
1049                                 return ret;
1050                 }
1051                 ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1052                 if (ret)
1053                         return ret;
1054                 ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1055                 if (ret)
1056                         return ret;
1057         }
1058
1059         return 0;
1060 }
1061
1062 /*
1063  * update all the cowonly tree roots on disk
1064  *
1065  * The error handling in this function may not be obvious. Any of the
1066  * failures will cause the file system to go offline. We still need
1067  * to clean up the delayed refs.
1068  */
1069 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
1070                                          struct btrfs_root *root)
1071 {
1072         struct btrfs_fs_info *fs_info = root->fs_info;
1073         struct list_head *next;
1074         struct extent_buffer *eb;
1075         int ret;
1076
1077         eb = btrfs_lock_root_node(fs_info->tree_root);
1078         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
1079                               0, &eb);
1080         btrfs_tree_unlock(eb);
1081         free_extent_buffer(eb);
1082
1083         if (ret)
1084                 return ret;
1085
1086         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1087         if (ret)
1088                 return ret;
1089
1090         ret = btrfs_run_dev_stats(trans, root->fs_info);
1091         if (ret)
1092                 return ret;
1093         ret = btrfs_run_dev_replace(trans, root->fs_info);
1094         if (ret)
1095                 return ret;
1096         ret = btrfs_run_qgroups(trans, root->fs_info);
1097         if (ret)
1098                 return ret;
1099
1100         /* run_qgroups might have added some more refs */
1101         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1102         if (ret)
1103                 return ret;
1104
1105         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
1106                 next = fs_info->dirty_cowonly_roots.next;
1107                 list_del_init(next);
1108                 root = list_entry(next, struct btrfs_root, dirty_list);
1109                 clear_bit(BTRFS_ROOT_DIRTY, &root->state);
1110
1111                 if (root != fs_info->extent_root)
1112                         list_add_tail(&root->dirty_list,
1113                                       &trans->transaction->switch_commits);
1114                 ret = update_cowonly_root(trans, root);
1115                 if (ret)
1116                         return ret;
1117         }
1118
1119         list_add_tail(&fs_info->extent_root->dirty_list,
1120                       &trans->transaction->switch_commits);
1121         btrfs_after_dev_replace_commit(fs_info);
1122
1123         return 0;
1124 }
1125
1126 /*
1127  * dead roots are old snapshots that need to be deleted.  This allocates
1128  * a dirty root struct and adds it into the list of dead roots that need to
1129  * be deleted
1130  */
1131 void btrfs_add_dead_root(struct btrfs_root *root)
1132 {
1133         spin_lock(&root->fs_info->trans_lock);
1134         if (list_empty(&root->root_list))
1135                 list_add_tail(&root->root_list, &root->fs_info->dead_roots);
1136         spin_unlock(&root->fs_info->trans_lock);
1137 }
1138
1139 /*
1140  * update all the cowonly tree roots on disk
1141  */
1142 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
1143                                     struct btrfs_root *root)
1144 {
1145         struct btrfs_root *gang[8];
1146         struct btrfs_fs_info *fs_info = root->fs_info;
1147         int i;
1148         int ret;
1149         int err = 0;
1150
1151         spin_lock(&fs_info->fs_roots_radix_lock);
1152         while (1) {
1153                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
1154                                                  (void **)gang, 0,
1155                                                  ARRAY_SIZE(gang),
1156                                                  BTRFS_ROOT_TRANS_TAG);
1157                 if (ret == 0)
1158                         break;
1159                 for (i = 0; i < ret; i++) {
1160                         root = gang[i];
1161                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
1162                                         (unsigned long)root->root_key.objectid,
1163                                         BTRFS_ROOT_TRANS_TAG);
1164                         spin_unlock(&fs_info->fs_roots_radix_lock);
1165
1166                         btrfs_free_log(trans, root);
1167                         btrfs_update_reloc_root(trans, root);
1168                         btrfs_orphan_commit_root(trans, root);
1169
1170                         btrfs_save_ino_cache(root, trans);
1171
1172                         /* see comments in should_cow_block() */
1173                         clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1174                         smp_mb__after_atomic();
1175
1176                         if (root->commit_root != root->node) {
1177                                 list_add_tail(&root->dirty_list,
1178                                         &trans->transaction->switch_commits);
1179                                 btrfs_set_root_node(&root->root_item,
1180                                                     root->node);
1181                         }
1182
1183                         err = btrfs_update_root(trans, fs_info->tree_root,
1184                                                 &root->root_key,
1185                                                 &root->root_item);
1186                         spin_lock(&fs_info->fs_roots_radix_lock);
1187                         if (err)
1188                                 break;
1189                 }
1190         }
1191         spin_unlock(&fs_info->fs_roots_radix_lock);
1192         return err;
1193 }
1194
1195 /*
1196  * defrag a given btree.
1197  * Every leaf in the btree is read and defragged.
1198  */
1199 int btrfs_defrag_root(struct btrfs_root *root)
1200 {
1201         struct btrfs_fs_info *info = root->fs_info;
1202         struct btrfs_trans_handle *trans;
1203         int ret;
1204
1205         if (test_and_set_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state))
1206                 return 0;
1207
1208         while (1) {
1209                 trans = btrfs_start_transaction(root, 0);
1210                 if (IS_ERR(trans))
1211                         return PTR_ERR(trans);
1212
1213                 ret = btrfs_defrag_leaves(trans, root);
1214
1215                 btrfs_end_transaction(trans, root);
1216                 btrfs_btree_balance_dirty(info->tree_root);
1217                 cond_resched();
1218
1219                 if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
1220                         break;
1221
1222                 if (btrfs_defrag_cancelled(root->fs_info)) {
1223                         pr_debug("BTRFS: defrag_root cancelled\n");
1224                         ret = -EAGAIN;
1225                         break;
1226                 }
1227         }
1228         clear_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state);
1229         return ret;
1230 }
1231
1232 /*
1233  * new snapshots need to be created at a very specific time in the
1234  * transaction commit.  This does the actual creation.
1235  *
1236  * Note:
1237  * If the error which may affect the commitment of the current transaction
1238  * happens, we should return the error number. If the error which just affect
1239  * the creation of the pending snapshots, just return 0.
1240  */
1241 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
1242                                    struct btrfs_fs_info *fs_info,
1243                                    struct btrfs_pending_snapshot *pending)
1244 {
1245         struct btrfs_key key;
1246         struct btrfs_root_item *new_root_item;
1247         struct btrfs_root *tree_root = fs_info->tree_root;
1248         struct btrfs_root *root = pending->root;
1249         struct btrfs_root *parent_root;
1250         struct btrfs_block_rsv *rsv;
1251         struct inode *parent_inode;
1252         struct btrfs_path *path;
1253         struct btrfs_dir_item *dir_item;
1254         struct dentry *dentry;
1255         struct extent_buffer *tmp;
1256         struct extent_buffer *old;
1257         struct timespec cur_time = CURRENT_TIME;
1258         int ret = 0;
1259         u64 to_reserve = 0;
1260         u64 index = 0;
1261         u64 objectid;
1262         u64 root_flags;
1263         uuid_le new_uuid;
1264
1265         path = btrfs_alloc_path();
1266         if (!path) {
1267                 pending->error = -ENOMEM;
1268                 return 0;
1269         }
1270
1271         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
1272         if (!new_root_item) {
1273                 pending->error = -ENOMEM;
1274                 goto root_item_alloc_fail;
1275         }
1276
1277         pending->error = btrfs_find_free_objectid(tree_root, &objectid);
1278         if (pending->error)
1279                 goto no_free_objectid;
1280
1281         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
1282
1283         if (to_reserve > 0) {
1284                 pending->error = btrfs_block_rsv_add(root,
1285                                                      &pending->block_rsv,
1286                                                      to_reserve,
1287                                                      BTRFS_RESERVE_NO_FLUSH);
1288                 if (pending->error)
1289                         goto no_free_objectid;
1290         }
1291
1292         key.objectid = objectid;
1293         key.offset = (u64)-1;
1294         key.type = BTRFS_ROOT_ITEM_KEY;
1295
1296         rsv = trans->block_rsv;
1297         trans->block_rsv = &pending->block_rsv;
1298         trans->bytes_reserved = trans->block_rsv->reserved;
1299
1300         dentry = pending->dentry;
1301         parent_inode = pending->dir;
1302         parent_root = BTRFS_I(parent_inode)->root;
1303         record_root_in_trans(trans, parent_root);
1304
1305         /*
1306          * insert the directory item
1307          */
1308         ret = btrfs_set_inode_index(parent_inode, &index);
1309         BUG_ON(ret); /* -ENOMEM */
1310
1311         /* check if there is a file/dir which has the same name. */
1312         dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1313                                          btrfs_ino(parent_inode),
1314                                          dentry->d_name.name,
1315                                          dentry->d_name.len, 0);
1316         if (dir_item != NULL && !IS_ERR(dir_item)) {
1317                 pending->error = -EEXIST;
1318                 goto dir_item_existed;
1319         } else if (IS_ERR(dir_item)) {
1320                 ret = PTR_ERR(dir_item);
1321                 btrfs_abort_transaction(trans, root, ret);
1322                 goto fail;
1323         }
1324         btrfs_release_path(path);
1325
1326         /*
1327          * pull in the delayed directory update
1328          * and the delayed inode item
1329          * otherwise we corrupt the FS during
1330          * snapshot
1331          */
1332         ret = btrfs_run_delayed_items(trans, root);
1333         if (ret) {      /* Transaction aborted */
1334                 btrfs_abort_transaction(trans, root, ret);
1335                 goto fail;
1336         }
1337
1338         record_root_in_trans(trans, root);
1339         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1340         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1341         btrfs_check_and_init_root_item(new_root_item);
1342
1343         root_flags = btrfs_root_flags(new_root_item);
1344         if (pending->readonly)
1345                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1346         else
1347                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1348         btrfs_set_root_flags(new_root_item, root_flags);
1349
1350         btrfs_set_root_generation_v2(new_root_item,
1351                         trans->transid);
1352         uuid_le_gen(&new_uuid);
1353         memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
1354         memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1355                         BTRFS_UUID_SIZE);
1356         if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
1357                 memset(new_root_item->received_uuid, 0,
1358                        sizeof(new_root_item->received_uuid));
1359                 memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1360                 memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1361                 btrfs_set_root_stransid(new_root_item, 0);
1362                 btrfs_set_root_rtransid(new_root_item, 0);
1363         }
1364         btrfs_set_stack_timespec_sec(&new_root_item->otime, cur_time.tv_sec);
1365         btrfs_set_stack_timespec_nsec(&new_root_item->otime, cur_time.tv_nsec);
1366         btrfs_set_root_otransid(new_root_item, trans->transid);
1367
1368         old = btrfs_lock_root_node(root);
1369         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1370         if (ret) {
1371                 btrfs_tree_unlock(old);
1372                 free_extent_buffer(old);
1373                 btrfs_abort_transaction(trans, root, ret);
1374                 goto fail;
1375         }
1376
1377         btrfs_set_lock_blocking(old);
1378
1379         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1380         /* clean up in any case */
1381         btrfs_tree_unlock(old);
1382         free_extent_buffer(old);
1383         if (ret) {
1384                 btrfs_abort_transaction(trans, root, ret);
1385                 goto fail;
1386         }
1387
1388         /*
1389          * We need to flush delayed refs in order to make sure all of our quota
1390          * operations have been done before we call btrfs_qgroup_inherit.
1391          */
1392         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1393         if (ret) {
1394                 btrfs_abort_transaction(trans, root, ret);
1395                 goto fail;
1396         }
1397
1398         ret = btrfs_qgroup_inherit(trans, fs_info,
1399                                    root->root_key.objectid,
1400                                    objectid, pending->inherit);
1401         if (ret) {
1402                 btrfs_abort_transaction(trans, root, ret);
1403                 goto fail;
1404         }
1405
1406         /* see comments in should_cow_block() */
1407         set_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1408         smp_wmb();
1409
1410         btrfs_set_root_node(new_root_item, tmp);
1411         /* record when the snapshot was created in key.offset */
1412         key.offset = trans->transid;
1413         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1414         btrfs_tree_unlock(tmp);
1415         free_extent_buffer(tmp);
1416         if (ret) {
1417                 btrfs_abort_transaction(trans, root, ret);
1418                 goto fail;
1419         }
1420
1421         /*
1422          * insert root back/forward references
1423          */
1424         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1425                                  parent_root->root_key.objectid,
1426                                  btrfs_ino(parent_inode), index,
1427                                  dentry->d_name.name, dentry->d_name.len);
1428         if (ret) {
1429                 btrfs_abort_transaction(trans, root, ret);
1430                 goto fail;
1431         }
1432
1433         key.offset = (u64)-1;
1434         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1435         if (IS_ERR(pending->snap)) {
1436                 ret = PTR_ERR(pending->snap);
1437                 btrfs_abort_transaction(trans, root, ret);
1438                 goto fail;
1439         }
1440
1441         ret = btrfs_reloc_post_snapshot(trans, pending);
1442         if (ret) {
1443                 btrfs_abort_transaction(trans, root, ret);
1444                 goto fail;
1445         }
1446
1447         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1448         if (ret) {
1449                 btrfs_abort_transaction(trans, root, ret);
1450                 goto fail;
1451         }
1452
1453         ret = btrfs_insert_dir_item(trans, parent_root,
1454                                     dentry->d_name.name, dentry->d_name.len,
1455                                     parent_inode, &key,
1456                                     BTRFS_FT_DIR, index);
1457         /* We have check then name at the beginning, so it is impossible. */
1458         BUG_ON(ret == -EEXIST || ret == -EOVERFLOW);
1459         if (ret) {
1460                 btrfs_abort_transaction(trans, root, ret);
1461                 goto fail;
1462         }
1463
1464         btrfs_i_size_write(parent_inode, parent_inode->i_size +
1465                                          dentry->d_name.len * 2);
1466         parent_inode->i_mtime = parent_inode->i_ctime = CURRENT_TIME;
1467         ret = btrfs_update_inode_fallback(trans, parent_root, parent_inode);
1468         if (ret) {
1469                 btrfs_abort_transaction(trans, root, ret);
1470                 goto fail;
1471         }
1472         ret = btrfs_uuid_tree_add(trans, fs_info->uuid_root, new_uuid.b,
1473                                   BTRFS_UUID_KEY_SUBVOL, objectid);
1474         if (ret) {
1475                 btrfs_abort_transaction(trans, root, ret);
1476                 goto fail;
1477         }
1478         if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
1479                 ret = btrfs_uuid_tree_add(trans, fs_info->uuid_root,
1480                                           new_root_item->received_uuid,
1481                                           BTRFS_UUID_KEY_RECEIVED_SUBVOL,
1482                                           objectid);
1483                 if (ret && ret != -EEXIST) {
1484                         btrfs_abort_transaction(trans, root, ret);
1485                         goto fail;
1486                 }
1487         }
1488 fail:
1489         pending->error = ret;
1490 dir_item_existed:
1491         trans->block_rsv = rsv;
1492         trans->bytes_reserved = 0;
1493 no_free_objectid:
1494         kfree(new_root_item);
1495 root_item_alloc_fail:
1496         btrfs_free_path(path);
1497         return ret;
1498 }
1499
1500 /*
1501  * create all the snapshots we've scheduled for creation
1502  */
1503 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1504                                              struct btrfs_fs_info *fs_info)
1505 {
1506         struct btrfs_pending_snapshot *pending, *next;
1507         struct list_head *head = &trans->transaction->pending_snapshots;
1508         int ret = 0;
1509
1510         list_for_each_entry_safe(pending, next, head, list) {
1511                 list_del(&pending->list);
1512                 ret = create_pending_snapshot(trans, fs_info, pending);
1513                 if (ret)
1514                         break;
1515         }
1516         return ret;
1517 }
1518
1519 static void update_super_roots(struct btrfs_root *root)
1520 {
1521         struct btrfs_root_item *root_item;
1522         struct btrfs_super_block *super;
1523
1524         super = root->fs_info->super_copy;
1525
1526         root_item = &root->fs_info->chunk_root->root_item;
1527         super->chunk_root = root_item->bytenr;
1528         super->chunk_root_generation = root_item->generation;
1529         super->chunk_root_level = root_item->level;
1530
1531         root_item = &root->fs_info->tree_root->root_item;
1532         super->root = root_item->bytenr;
1533         super->generation = root_item->generation;
1534         super->root_level = root_item->level;
1535         if (btrfs_test_opt(root, SPACE_CACHE))
1536                 super->cache_generation = root_item->generation;
1537         if (root->fs_info->update_uuid_tree_gen)
1538                 super->uuid_tree_generation = root_item->generation;
1539 }
1540
1541 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1542 {
1543         struct btrfs_transaction *trans;
1544         int ret = 0;
1545
1546         spin_lock(&info->trans_lock);
1547         trans = info->running_transaction;
1548         if (trans)
1549                 ret = (trans->state >= TRANS_STATE_COMMIT_START);
1550         spin_unlock(&info->trans_lock);
1551         return ret;
1552 }
1553
1554 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1555 {
1556         struct btrfs_transaction *trans;
1557         int ret = 0;
1558
1559         spin_lock(&info->trans_lock);
1560         trans = info->running_transaction;
1561         if (trans)
1562                 ret = is_transaction_blocked(trans);
1563         spin_unlock(&info->trans_lock);
1564         return ret;
1565 }
1566
1567 /*
1568  * wait for the current transaction commit to start and block subsequent
1569  * transaction joins
1570  */
1571 static void wait_current_trans_commit_start(struct btrfs_root *root,
1572                                             struct btrfs_transaction *trans)
1573 {
1574         wait_event(root->fs_info->transaction_blocked_wait,
1575                    trans->state >= TRANS_STATE_COMMIT_START ||
1576                    trans->aborted);
1577 }
1578
1579 /*
1580  * wait for the current transaction to start and then become unblocked.
1581  * caller holds ref.
1582  */
1583 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1584                                          struct btrfs_transaction *trans)
1585 {
1586         wait_event(root->fs_info->transaction_wait,
1587                    trans->state >= TRANS_STATE_UNBLOCKED ||
1588                    trans->aborted);
1589 }
1590
1591 /*
1592  * commit transactions asynchronously. once btrfs_commit_transaction_async
1593  * returns, any subsequent transaction will not be allowed to join.
1594  */
1595 struct btrfs_async_commit {
1596         struct btrfs_trans_handle *newtrans;
1597         struct btrfs_root *root;
1598         struct work_struct work;
1599 };
1600
1601 static void do_async_commit(struct work_struct *work)
1602 {
1603         struct btrfs_async_commit *ac =
1604                 container_of(work, struct btrfs_async_commit, work);
1605
1606         /*
1607          * We've got freeze protection passed with the transaction.
1608          * Tell lockdep about it.
1609          */
1610         if (ac->newtrans->type & __TRANS_FREEZABLE)
1611                 rwsem_acquire_read(
1612                      &ac->root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1613                      0, 1, _THIS_IP_);
1614
1615         current->journal_info = ac->newtrans;
1616
1617         btrfs_commit_transaction(ac->newtrans, ac->root);
1618         kfree(ac);
1619 }
1620
1621 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1622                                    struct btrfs_root *root,
1623                                    int wait_for_unblock)
1624 {
1625         struct btrfs_async_commit *ac;
1626         struct btrfs_transaction *cur_trans;
1627
1628         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1629         if (!ac)
1630                 return -ENOMEM;
1631
1632         INIT_WORK(&ac->work, do_async_commit);
1633         ac->root = root;
1634         ac->newtrans = btrfs_join_transaction(root);
1635         if (IS_ERR(ac->newtrans)) {
1636                 int err = PTR_ERR(ac->newtrans);
1637                 kfree(ac);
1638                 return err;
1639         }
1640
1641         /* take transaction reference */
1642         cur_trans = trans->transaction;
1643         atomic_inc(&cur_trans->use_count);
1644
1645         btrfs_end_transaction(trans, root);
1646
1647         /*
1648          * Tell lockdep we've released the freeze rwsem, since the
1649          * async commit thread will be the one to unlock it.
1650          */
1651         if (ac->newtrans->type & __TRANS_FREEZABLE)
1652                 rwsem_release(
1653                         &root->fs_info->sb->s_writers.lock_map[SB_FREEZE_FS-1],
1654                         1, _THIS_IP_);
1655
1656         schedule_work(&ac->work);
1657
1658         /* wait for transaction to start and unblock */
1659         if (wait_for_unblock)
1660                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1661         else
1662                 wait_current_trans_commit_start(root, cur_trans);
1663
1664         if (current->journal_info == trans)
1665                 current->journal_info = NULL;
1666
1667         btrfs_put_transaction(cur_trans);
1668         return 0;
1669 }
1670
1671
1672 static void cleanup_transaction(struct btrfs_trans_handle *trans,
1673                                 struct btrfs_root *root, int err)
1674 {
1675         struct btrfs_transaction *cur_trans = trans->transaction;
1676         DEFINE_WAIT(wait);
1677
1678         WARN_ON(trans->use_count > 1);
1679
1680         btrfs_abort_transaction(trans, root, err);
1681
1682         spin_lock(&root->fs_info->trans_lock);
1683
1684         /*
1685          * If the transaction is removed from the list, it means this
1686          * transaction has been committed successfully, so it is impossible
1687          * to call the cleanup function.
1688          */
1689         BUG_ON(list_empty(&cur_trans->list));
1690
1691         list_del_init(&cur_trans->list);
1692         if (cur_trans == root->fs_info->running_transaction) {
1693                 cur_trans->state = TRANS_STATE_COMMIT_DOING;
1694                 spin_unlock(&root->fs_info->trans_lock);
1695                 wait_event(cur_trans->writer_wait,
1696                            atomic_read(&cur_trans->num_writers) == 1);
1697
1698                 spin_lock(&root->fs_info->trans_lock);
1699         }
1700         spin_unlock(&root->fs_info->trans_lock);
1701
1702         btrfs_cleanup_one_transaction(trans->transaction, root);
1703
1704         spin_lock(&root->fs_info->trans_lock);
1705         if (cur_trans == root->fs_info->running_transaction)
1706                 root->fs_info->running_transaction = NULL;
1707         spin_unlock(&root->fs_info->trans_lock);
1708
1709         if (trans->type & __TRANS_FREEZABLE)
1710                 sb_end_intwrite(root->fs_info->sb);
1711         btrfs_put_transaction(cur_trans);
1712         btrfs_put_transaction(cur_trans);
1713
1714         trace_btrfs_transaction_commit(root);
1715
1716         if (current->journal_info == trans)
1717                 current->journal_info = NULL;
1718         btrfs_scrub_cancel(root->fs_info);
1719
1720         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1721 }
1722
1723 static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)
1724 {
1725         if (btrfs_test_opt(fs_info->tree_root, FLUSHONCOMMIT))
1726                 return btrfs_start_delalloc_roots(fs_info, 1, -1);
1727         return 0;
1728 }
1729
1730 static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
1731 {
1732         if (btrfs_test_opt(fs_info->tree_root, FLUSHONCOMMIT))
1733                 btrfs_wait_ordered_roots(fs_info, -1);
1734 }
1735
1736 static inline void
1737 btrfs_wait_pending_ordered(struct btrfs_transaction *cur_trans,
1738                            struct btrfs_fs_info *fs_info)
1739 {
1740         struct btrfs_ordered_extent *ordered;
1741
1742         spin_lock(&fs_info->trans_lock);
1743         while (!list_empty(&cur_trans->pending_ordered)) {
1744                 ordered = list_first_entry(&cur_trans->pending_ordered,
1745                                            struct btrfs_ordered_extent,
1746                                            trans_list);
1747                 list_del_init(&ordered->trans_list);
1748                 spin_unlock(&fs_info->trans_lock);
1749
1750                 wait_event(ordered->wait, test_bit(BTRFS_ORDERED_COMPLETE,
1751                                                    &ordered->flags));
1752                 btrfs_put_ordered_extent(ordered);
1753                 spin_lock(&fs_info->trans_lock);
1754         }
1755         spin_unlock(&fs_info->trans_lock);
1756 }
1757
1758 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1759                              struct btrfs_root *root)
1760 {
1761         struct btrfs_transaction *cur_trans = trans->transaction;
1762         struct btrfs_transaction *prev_trans = NULL;
1763         struct btrfs_inode *btree_ino = BTRFS_I(root->fs_info->btree_inode);
1764         int ret;
1765
1766         /* Stop the commit early if ->aborted is set */
1767         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1768                 ret = cur_trans->aborted;
1769                 btrfs_end_transaction(trans, root);
1770                 return ret;
1771         }
1772
1773         /* make a pass through all the delayed refs we have so far
1774          * any runnings procs may add more while we are here
1775          */
1776         ret = btrfs_run_delayed_refs(trans, root, 0);
1777         if (ret) {
1778                 btrfs_end_transaction(trans, root);
1779                 return ret;
1780         }
1781
1782         btrfs_trans_release_metadata(trans, root);
1783         trans->block_rsv = NULL;
1784         if (trans->qgroup_reserved) {
1785                 btrfs_qgroup_free(root, trans->qgroup_reserved);
1786                 trans->qgroup_reserved = 0;
1787         }
1788
1789         cur_trans = trans->transaction;
1790
1791         /*
1792          * set the flushing flag so procs in this transaction have to
1793          * start sending their work down.
1794          */
1795         cur_trans->delayed_refs.flushing = 1;
1796         smp_wmb();
1797
1798         if (!list_empty(&trans->new_bgs))
1799                 btrfs_create_pending_block_groups(trans, root);
1800
1801         ret = btrfs_run_delayed_refs(trans, root, 0);
1802         if (ret) {
1803                 btrfs_end_transaction(trans, root);
1804                 return ret;
1805         }
1806
1807         spin_lock(&root->fs_info->trans_lock);
1808         list_splice(&trans->ordered, &cur_trans->pending_ordered);
1809         if (cur_trans->state >= TRANS_STATE_COMMIT_START) {
1810                 spin_unlock(&root->fs_info->trans_lock);
1811                 atomic_inc(&cur_trans->use_count);
1812                 ret = btrfs_end_transaction(trans, root);
1813
1814                 wait_for_commit(root, cur_trans);
1815
1816                 btrfs_put_transaction(cur_trans);
1817
1818                 return ret;
1819         }
1820
1821         cur_trans->state = TRANS_STATE_COMMIT_START;
1822         wake_up(&root->fs_info->transaction_blocked_wait);
1823
1824         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1825                 prev_trans = list_entry(cur_trans->list.prev,
1826                                         struct btrfs_transaction, list);
1827                 if (prev_trans->state != TRANS_STATE_COMPLETED) {
1828                         atomic_inc(&prev_trans->use_count);
1829                         spin_unlock(&root->fs_info->trans_lock);
1830
1831                         wait_for_commit(root, prev_trans);
1832
1833                         btrfs_put_transaction(prev_trans);
1834                 } else {
1835                         spin_unlock(&root->fs_info->trans_lock);
1836                 }
1837         } else {
1838                 spin_unlock(&root->fs_info->trans_lock);
1839         }
1840
1841         extwriter_counter_dec(cur_trans, trans->type);
1842
1843         ret = btrfs_start_delalloc_flush(root->fs_info);
1844         if (ret)
1845                 goto cleanup_transaction;
1846
1847         ret = btrfs_run_delayed_items(trans, root);
1848         if (ret)
1849                 goto cleanup_transaction;
1850
1851         wait_event(cur_trans->writer_wait,
1852                    extwriter_counter_read(cur_trans) == 0);
1853
1854         /* some pending stuffs might be added after the previous flush. */
1855         ret = btrfs_run_delayed_items(trans, root);
1856         if (ret)
1857                 goto cleanup_transaction;
1858
1859         btrfs_wait_delalloc_flush(root->fs_info);
1860
1861         btrfs_wait_pending_ordered(cur_trans, root->fs_info);
1862
1863         btrfs_scrub_pause(root);
1864         /*
1865          * Ok now we need to make sure to block out any other joins while we
1866          * commit the transaction.  We could have started a join before setting
1867          * COMMIT_DOING so make sure to wait for num_writers to == 1 again.
1868          */
1869         spin_lock(&root->fs_info->trans_lock);
1870         cur_trans->state = TRANS_STATE_COMMIT_DOING;
1871         spin_unlock(&root->fs_info->trans_lock);
1872         wait_event(cur_trans->writer_wait,
1873                    atomic_read(&cur_trans->num_writers) == 1);
1874
1875         /* ->aborted might be set after the previous check, so check it */
1876         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1877                 ret = cur_trans->aborted;
1878                 goto scrub_continue;
1879         }
1880         /*
1881          * the reloc mutex makes sure that we stop
1882          * the balancing code from coming in and moving
1883          * extents around in the middle of the commit
1884          */
1885         mutex_lock(&root->fs_info->reloc_mutex);
1886
1887         /*
1888          * We needn't worry about the delayed items because we will
1889          * deal with them in create_pending_snapshot(), which is the
1890          * core function of the snapshot creation.
1891          */
1892         ret = create_pending_snapshots(trans, root->fs_info);
1893         if (ret) {
1894                 mutex_unlock(&root->fs_info->reloc_mutex);
1895                 goto scrub_continue;
1896         }
1897
1898         /*
1899          * We insert the dir indexes of the snapshots and update the inode
1900          * of the snapshots' parents after the snapshot creation, so there
1901          * are some delayed items which are not dealt with. Now deal with
1902          * them.
1903          *
1904          * We needn't worry that this operation will corrupt the snapshots,
1905          * because all the tree which are snapshoted will be forced to COW
1906          * the nodes and leaves.
1907          */
1908         ret = btrfs_run_delayed_items(trans, root);
1909         if (ret) {
1910                 mutex_unlock(&root->fs_info->reloc_mutex);
1911                 goto scrub_continue;
1912         }
1913
1914         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1915         if (ret) {
1916                 mutex_unlock(&root->fs_info->reloc_mutex);
1917                 goto scrub_continue;
1918         }
1919
1920         /*
1921          * make sure none of the code above managed to slip in a
1922          * delayed item
1923          */
1924         btrfs_assert_delayed_root_empty(root);
1925
1926         WARN_ON(cur_trans != trans->transaction);
1927
1928         /* btrfs_commit_tree_roots is responsible for getting the
1929          * various roots consistent with each other.  Every pointer
1930          * in the tree of tree roots has to point to the most up to date
1931          * root for every subvolume and other tree.  So, we have to keep
1932          * the tree logging code from jumping in and changing any
1933          * of the trees.
1934          *
1935          * At this point in the commit, there can't be any tree-log
1936          * writers, but a little lower down we drop the trans mutex
1937          * and let new people in.  By holding the tree_log_mutex
1938          * from now until after the super is written, we avoid races
1939          * with the tree-log code.
1940          */
1941         mutex_lock(&root->fs_info->tree_log_mutex);
1942
1943         ret = commit_fs_roots(trans, root);
1944         if (ret) {
1945                 mutex_unlock(&root->fs_info->tree_log_mutex);
1946                 mutex_unlock(&root->fs_info->reloc_mutex);
1947                 goto scrub_continue;
1948         }
1949
1950         /*
1951          * Since the transaction is done, we can apply the pending changes
1952          * before the next transaction.
1953          */
1954         btrfs_apply_pending_changes(root->fs_info);
1955
1956         /* commit_fs_roots gets rid of all the tree log roots, it is now
1957          * safe to free the root of tree log roots
1958          */
1959         btrfs_free_log_root_tree(trans, root->fs_info);
1960
1961         ret = commit_cowonly_roots(trans, root);
1962         if (ret) {
1963                 mutex_unlock(&root->fs_info->tree_log_mutex);
1964                 mutex_unlock(&root->fs_info->reloc_mutex);
1965                 goto scrub_continue;
1966         }
1967
1968         /*
1969          * The tasks which save the space cache and inode cache may also
1970          * update ->aborted, check it.
1971          */
1972         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1973                 ret = cur_trans->aborted;
1974                 mutex_unlock(&root->fs_info->tree_log_mutex);
1975                 mutex_unlock(&root->fs_info->reloc_mutex);
1976                 goto scrub_continue;
1977         }
1978
1979         btrfs_prepare_extent_commit(trans, root);
1980
1981         cur_trans = root->fs_info->running_transaction;
1982
1983         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1984                             root->fs_info->tree_root->node);
1985         list_add_tail(&root->fs_info->tree_root->dirty_list,
1986                       &cur_trans->switch_commits);
1987
1988         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1989                             root->fs_info->chunk_root->node);
1990         list_add_tail(&root->fs_info->chunk_root->dirty_list,
1991                       &cur_trans->switch_commits);
1992
1993         switch_commit_roots(cur_trans, root->fs_info);
1994
1995         assert_qgroups_uptodate(trans);
1996         ASSERT(list_empty(&cur_trans->dirty_bgs));
1997         update_super_roots(root);
1998
1999         btrfs_set_super_log_root(root->fs_info->super_copy, 0);
2000         btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
2001         memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
2002                sizeof(*root->fs_info->super_copy));
2003
2004         btrfs_update_commit_device_size(root->fs_info);
2005         btrfs_update_commit_device_bytes_used(root, cur_trans);
2006
2007         clear_bit(BTRFS_INODE_BTREE_LOG1_ERR, &btree_ino->runtime_flags);
2008         clear_bit(BTRFS_INODE_BTREE_LOG2_ERR, &btree_ino->runtime_flags);
2009
2010         spin_lock(&root->fs_info->trans_lock);
2011         cur_trans->state = TRANS_STATE_UNBLOCKED;
2012         root->fs_info->running_transaction = NULL;
2013         spin_unlock(&root->fs_info->trans_lock);
2014         mutex_unlock(&root->fs_info->reloc_mutex);
2015
2016         wake_up(&root->fs_info->transaction_wait);
2017
2018         ret = btrfs_write_and_wait_transaction(trans, root);
2019         if (ret) {
2020                 btrfs_error(root->fs_info, ret,
2021                             "Error while writing out transaction");
2022                 mutex_unlock(&root->fs_info->tree_log_mutex);
2023                 goto scrub_continue;
2024         }
2025
2026         ret = write_ctree_super(trans, root, 0);
2027         if (ret) {
2028                 mutex_unlock(&root->fs_info->tree_log_mutex);
2029                 goto scrub_continue;
2030         }
2031
2032         /*
2033          * the super is written, we can safely allow the tree-loggers
2034          * to go about their business
2035          */
2036         mutex_unlock(&root->fs_info->tree_log_mutex);
2037
2038         btrfs_finish_extent_commit(trans, root);
2039
2040         root->fs_info->last_trans_committed = cur_trans->transid;
2041         /*
2042          * We needn't acquire the lock here because there is no other task
2043          * which can change it.
2044          */
2045         cur_trans->state = TRANS_STATE_COMPLETED;
2046         wake_up(&cur_trans->commit_wait);
2047
2048         spin_lock(&root->fs_info->trans_lock);
2049         list_del_init(&cur_trans->list);
2050         spin_unlock(&root->fs_info->trans_lock);
2051
2052         btrfs_put_transaction(cur_trans);
2053         btrfs_put_transaction(cur_trans);
2054
2055         if (trans->type & __TRANS_FREEZABLE)
2056                 sb_end_intwrite(root->fs_info->sb);
2057
2058         trace_btrfs_transaction_commit(root);
2059
2060         btrfs_scrub_continue(root);
2061
2062         if (current->journal_info == trans)
2063                 current->journal_info = NULL;
2064
2065         kmem_cache_free(btrfs_trans_handle_cachep, trans);
2066
2067         if (current != root->fs_info->transaction_kthread)
2068                 btrfs_run_delayed_iputs(root);
2069
2070         return ret;
2071
2072 scrub_continue:
2073         btrfs_scrub_continue(root);
2074 cleanup_transaction:
2075         btrfs_trans_release_metadata(trans, root);
2076         trans->block_rsv = NULL;
2077         if (trans->qgroup_reserved) {
2078                 btrfs_qgroup_free(root, trans->qgroup_reserved);
2079                 trans->qgroup_reserved = 0;
2080         }
2081         btrfs_warn(root->fs_info, "Skipping commit of aborted transaction.");
2082         if (current->journal_info == trans)
2083                 current->journal_info = NULL;
2084         cleanup_transaction(trans, root, ret);
2085
2086         return ret;
2087 }
2088
2089 /*
2090  * return < 0 if error
2091  * 0 if there are no more dead_roots at the time of call
2092  * 1 there are more to be processed, call me again
2093  *
2094  * The return value indicates there are certainly more snapshots to delete, but
2095  * if there comes a new one during processing, it may return 0. We don't mind,
2096  * because btrfs_commit_super will poke cleaner thread and it will process it a
2097  * few seconds later.
2098  */
2099 int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root)
2100 {
2101         int ret;
2102         struct btrfs_fs_info *fs_info = root->fs_info;
2103
2104         spin_lock(&fs_info->trans_lock);
2105         if (list_empty(&fs_info->dead_roots)) {
2106                 spin_unlock(&fs_info->trans_lock);
2107                 return 0;
2108         }
2109         root = list_first_entry(&fs_info->dead_roots,
2110                         struct btrfs_root, root_list);
2111         list_del_init(&root->root_list);
2112         spin_unlock(&fs_info->trans_lock);
2113
2114         pr_debug("BTRFS: cleaner removing %llu\n", root->objectid);
2115
2116         btrfs_kill_all_delayed_nodes(root);
2117
2118         if (btrfs_header_backref_rev(root->node) <
2119                         BTRFS_MIXED_BACKREF_REV)
2120                 ret = btrfs_drop_snapshot(root, NULL, 0, 0);
2121         else
2122                 ret = btrfs_drop_snapshot(root, NULL, 1, 0);
2123
2124         return (ret < 0) ? 0 : 1;
2125 }
2126
2127 void btrfs_apply_pending_changes(struct btrfs_fs_info *fs_info)
2128 {
2129         unsigned long prev;
2130         unsigned long bit;
2131
2132         prev = cmpxchg(&fs_info->pending_changes, 0, 0);
2133         if (!prev)
2134                 return;
2135
2136         bit = 1 << BTRFS_PENDING_SET_INODE_MAP_CACHE;
2137         if (prev & bit)
2138                 btrfs_set_opt(fs_info->mount_opt, INODE_MAP_CACHE);
2139         prev &= ~bit;
2140
2141         bit = 1 << BTRFS_PENDING_CLEAR_INODE_MAP_CACHE;
2142         if (prev & bit)
2143                 btrfs_clear_opt(fs_info->mount_opt, INODE_MAP_CACHE);
2144         prev &= ~bit;
2145
2146         bit = 1 << BTRFS_PENDING_COMMIT;
2147         if (prev & bit)
2148                 btrfs_debug(fs_info, "pending commit done");
2149         prev &= ~bit;
2150
2151         if (prev)
2152                 btrfs_warn(fs_info,
2153                         "unknown pending changes left 0x%lx, ignoring", prev);
2154 }