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