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