kernel/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                         printk(KERN_ERR "pending csums is %llu\n",
  69                                transaction->delayed_refs.pending_csums);
  70                 while (!list_empty(&transaction->pending_chunks)) {
  71                         struct extent_map *em;
  72
  73                         em = list_first_entry(&transaction->pending_chunks,
  74                                               struct extent_map, list);
  75                         list_del_init(&em->list);
  76                         free_extent_map(em);
  77                 }
  78                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  79         }
  80 }
  81
  82 static void clear_btree_io_tree(struct extent_io_tree *tree)
  83 {
  84         spin_lock(&tree->lock);
  85         /*
  86          * Do a single barrier for the waitqueue_active check here, the state
  87          * of the waitqueue should not change once clear_btree_io_tree is
  88          * called.
  89          */
  90         smp_mb();
  91         while (!RB_EMPTY_ROOT(&tree->state)) {
  92                 struct rb_node *node;
  93                 struct extent_state *state;
  94
  95                 node = rb_first(&tree->state);
  96                 state = rb_entry(node, struct extent_state, rb_node);
  97                 rb_erase(&state->rb_node, &tree->state);
  98                 RB_CLEAR_NODE(&state->rb_node);
  99                 /*
 100                  * btree io trees aren't supposed to have tasks waiting for
 101                  * changes in the flags of extent states ever.
 102                  */
 103                 ASSERT(!waitqueue_active(&state->wq));
 104                 free_extent_state(state);
 105
 106                 cond_resched_lock(&tree->lock);
 107         }
 108         spin_unlock(&tree->lock);
 109 }
 110
 111 static noinline void switch_commit_roots(struct btrfs_transaction *trans,
 112                                          struct btrfs_fs_info *fs_info)
 113 {
 114         struct btrfs_root *root, *tmp;
 115
 116         down_write(&fs_info->commit_root_sem);
 117         list_for_each_entry_safe(root, tmp, &trans->switch_commits,
 118                                  dirty_list) {
 119                 list_del_init(&root->dirty_list);
 120                 free_extent_buffer(root->commit_root);
 121                 root->commit_root = btrfs_root_node(root);
 122                 if (is_fstree(root->objectid))
 123                         btrfs_unpin_free_ino(root);
 124                 clear_btree_io_tree(&root->dirty_log_pages);
 125         }
 126
 127         /* We can free old roots now. */
 128         spin_lock(&trans->dropped_roots_lock);
 129         while (!list_empty(&trans->dropped_roots)) {
 130                 root = list_first_entry(&trans->dropped_roots,
 131                                         struct btrfs_root, root_list);
 132                 list_del_init(&root->root_list);
 133                 spin_unlock(&trans->dropped_roots_lock);
 134                 btrfs_drop_and_free_fs_root(fs_info, root);
 135                 spin_lock(&trans->dropped_roots_lock);
 136         }
 137         spin_unlock(&trans->dropped_roots_lock);
 138         up_write(&fs_info->commit_root_sem);
 139 }
 140
 141 static inline void extwriter_counter_inc(struct btrfs_transaction *trans,
 142                                          unsigned int type)
 143 {
 144         if (type & TRANS_EXTWRITERS)
 145                 atomic_inc(&trans->num_extwriters);
 146 }
 147
 148 static inline void extwriter_counter_dec(struct btrfs_transaction *trans,
 149                                          unsigned int type)
 150 {
 151         if (type & TRANS_EXTWRITERS)
 152                 atomic_dec(&trans->num_extwriters);
 153 }
 154
 155 static inline void extwriter_counter_init(struct btrfs_transaction *trans,
 156                                           unsigned int type)
 157 {
 158         atomic_set(&trans->num_extwriters, ((type & TRANS_EXTWRITERS) ? 1 : 0));
 159 }
 160
 161 static inline int extwriter_counter_read(struct btrfs_transaction *trans)
 162 {
 163         return atomic_read(&trans->num_extwriters);
 164 }
 165
 166 /*
 167  * either allocate a new transaction or hop into the existing one
 168  */
 169 static noinline int join_transaction(struct btrfs_root *root, unsigned int type)
 170 {
 171         struct btrfs_transaction *cur_trans;
 172         struct btrfs_fs_info *fs_info = root->fs_info;
 173
 174         spin_lock(&fs_info->trans_lock);
 175 loop:
 176         /* The file system has been taken offline. No new transactions. */
 177         if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 178                 spin_unlock(&fs_info->trans_lock);
 179                 return -EROFS;
 180         }
 181
 182         cur_trans = fs_info->running_transaction;
 183         if (cur_trans) {
 184                 if (cur_trans->aborted) {
 185                         spin_unlock(&fs_info->trans_lock);
 186                         return cur_trans->aborted;
 187                 }
 188                 if (btrfs_blocked_trans_types[cur_trans->state] & type) {
 189                         spin_unlock(&fs_info->trans_lock);
 190                         return -EBUSY;
 191                 }
 192                 atomic_inc(&cur_trans->use_count);
 193                 atomic_inc(&cur_trans->num_writers);
 194                 extwriter_counter_inc(cur_trans, type);
 195                 spin_unlock(&fs_info->trans_lock);
 196                 return 0;
 197         }
 198         spin_unlock(&fs_info->trans_lock);
 199
 200         /*
 201          * If we are ATTACH, we just want to catch the current transaction,
 202          * and commit it. If there is no transaction, just return ENOENT.
 203          */
 204         if (type == TRANS_ATTACH)
 205                 return -ENOENT;
 206
 207         /*
 208          * JOIN_NOLOCK only happens during the transaction commit, so
 209          * it is impossible that ->running_transaction is NULL
 210          */
 211         BUG_ON(type == TRANS_JOIN_NOLOCK);
 212
 213         cur_trans = kmem_cache_alloc(btrfs_transaction_cachep, GFP_NOFS);
 214         if (!cur_trans)
 215                 return -ENOMEM;
 216
 217         spin_lock(&fs_info->trans_lock);
 218         if (fs_info->running_transaction) {
 219                 /*
 220                  * someone started a transaction after we unlocked.  Make sure
 221                  * to redo the checks above
 222                  */
 223                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 224                 goto loop;
 225         } else if (test_bit(BTRFS_FS_STATE_ERROR, &fs_info->fs_state)) {
 226                 spin_unlock(&fs_info->trans_lock);
 227                 kmem_cache_free(btrfs_transaction_cachep, cur_trans);
 228                 return -EROFS;
 229         }
 230
 231         atomic_set(&cur_trans->num_writers, 1);
 232         extwriter_counter_init(cur_trans, type);
 233         init_waitqueue_head(&cur_trans->writer_wait);
 234         init_waitqueue_head(&cur_trans->commit_wait);
 235         init_waitqueue_head(&cur_trans->pending_wait);
 236         cur_trans->state = TRANS_STATE_RUNNING;
 237         /*
 238          * One for this trans handle, one so it will live on until we
 239          * commit the transaction.
 240          */
 241         atomic_set(&cur_trans->use_count, 2);
 242         atomic_set(&cur_trans->pending_ordered, 0);
 243         cur_trans->flags = 0;
 244         cur_trans->start_time = get_seconds();
 245
 246         memset(&cur_trans->delayed_refs, 0, sizeof(cur_trans->delayed_refs));
 247
 248         cur_trans->delayed_refs.href_root = RB_ROOT;
 249         cur_trans->delayed_refs.dirty_extent_root = RB_ROOT;
 250         atomic_set(&cur_trans->delayed_refs.num_entries, 0);
 251
 252         /*
 253          * although the tree mod log is per file system and not per transaction,
 254          * the log must never go across transaction boundaries.
 255          */
 256         smp_mb();
 257         if (!list_empty(&fs_info->tree_mod_seq_list))
 258                 WARN(1, KERN_ERR "BTRFS: tree_mod_seq_list not empty when "
 259                         "creating a fresh transaction\n");
 260         if (!RB_EMPTY_ROOT(&fs_info->tree_mod_log))
 261                 WARN(1, KERN_ERR "BTRFS: tree_mod_log rb tree not empty when "
 262                         "creating a fresh transaction\n");
 263         atomic64_set(&fs_info->tree_mod_seq, 0);
 264
 265         spin_lock_init(&cur_trans->delayed_refs.lock);
 266
 267         INIT_LIST_HEAD(&cur_trans->pending_snapshots);
 268         INIT_LIST_HEAD(&cur_trans->pending_chunks);
 269         INIT_LIST_HEAD(&cur_trans->switch_commits);
 270         INIT_LIST_HEAD(&cur_trans->dirty_bgs);
 271         INIT_LIST_HEAD(&cur_trans->io_bgs);
 272         INIT_LIST_HEAD(&cur_trans->dropped_roots);
 273         mutex_init(&cur_trans->cache_write_mutex);
 274         cur_trans->num_dirty_bgs = 0;
 275         spin_lock_init(&cur_trans->dirty_bgs_lock);
 276         INIT_LIST_HEAD(&cur_trans->deleted_bgs);
 277         spin_lock_init(&cur_trans->dropped_roots_lock);
 278         list_add_tail(&cur_trans->list, &fs_info->trans_list);
 279         extent_io_tree_init(&cur_trans->dirty_pages,
 280                              fs_info->btree_inode->i_mapping);
 281         fs_info->generation++;
 282         cur_trans->transid = fs_info->generation;
 283         fs_info->running_transaction = cur_trans;
 284         cur_trans->aborted = 0;
 285         spin_unlock(&fs_info->trans_lock);
 286
 287         return 0;
 288 }
 289
 290 /*
 291  * this does all the record keeping required to make sure that a reference
 292  * counted root is properly recorded in a given transaction.  This is required
 293  * to make sure the old root from before we joined the transaction is deleted
 294  * when the transaction commits
 295  */
 296 static int record_root_in_trans(struct btrfs_trans_handle *trans,
 297                                struct btrfs_root *root)
 298 {
 299         if (test_bit(BTRFS_ROOT_REF_COWS, &root->state) &&
 300             root->last_trans < trans->transid) {
 301                 WARN_ON(root == root->fs_info->extent_root);
 302                 WARN_ON(root->commit_root != root->node);
 303
 304                 /*
 305                  * see below for IN_TRANS_SETUP usage rules
 306                  * we have the reloc mutex held now, so there
 307                  * is only one writer in this function
 308                  */
 309                 set_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
 310
 311                 /* make sure readers find IN_TRANS_SETUP before
 312                  * they find our root->last_trans update
 313                  */
 314                 smp_wmb();
 315
 316                 spin_lock(&root->fs_info->fs_roots_radix_lock);
 317                 if (root->last_trans == trans->transid) {
 318                         spin_unlock(&root->fs_info->fs_roots_radix_lock);
 319                         return 0;
 320                 }
 321                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 322                            (unsigned long)root->root_key.objectid,
 323                            BTRFS_ROOT_TRANS_TAG);
 324                 spin_unlock(&root->fs_info->fs_roots_radix_lock);
 325                 root->last_trans = trans->transid;
 326
 327                 /* this is pretty tricky.  We don't want to
 328                  * take the relocation lock in btrfs_record_root_in_trans
 329                  * unless we're really doing the first setup for this root in
 330                  * this transaction.
 331                  *
 332                  * Normally we'd use root->last_trans as a flag to decide
 333                  * if we want to take the expensive mutex.
 334                  *
 335                  * But, we have to set root->last_trans before we
 336                  * init the relocation root, otherwise, we trip over warnings
 337                  * in ctree.c.  The solution used here is to flag ourselves
 338                  * with root IN_TRANS_SETUP.  When this is 1, we're still
 339                  * fixing up the reloc trees and everyone must wait.
 340                  *
 341                  * When this is zero, they can trust root->last_trans and fly
 342                  * through btrfs_record_root_in_trans without having to take the
 343                  * lock.  smp_wmb() makes sure that all the writes above are
 344                  * done before we pop in the zero below
 345                  */
 346                 btrfs_init_reloc_root(trans, root);
 347                 smp_mb__before_atomic();
 348                 clear_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state);
 349         }
 350         return 0;
 351 }
 352
 353
 354 void btrfs_add_dropped_root(struct btrfs_trans_handle *trans,
 355                             struct btrfs_root *root)
 356 {
 357         struct btrfs_transaction *cur_trans = trans->transaction;
 358
 359         /* Add ourselves to the transaction dropped list */
 360         spin_lock(&cur_trans->dropped_roots_lock);
 361         list_add_tail(&root->root_list, &cur_trans->dropped_roots);
 362         spin_unlock(&cur_trans->dropped_roots_lock);
 363
 364         /* Make sure we don't try to update the root at commit time */
 365         spin_lock(&root->fs_info->fs_roots_radix_lock);
 366         radix_tree_tag_clear(&root->fs_info->fs_roots_radix,
 367                              (unsigned long)root->root_key.objectid,
 368                              BTRFS_ROOT_TRANS_TAG);
 369         spin_unlock(&root->fs_info->fs_roots_radix_lock);
 370 }
 371
 372 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 373                                struct btrfs_root *root)
 374 {
 375         if (!test_bit(BTRFS_ROOT_REF_COWS, &root->state))
 376                 return 0;
 377
 378         /*
 379          * see record_root_in_trans for comments about IN_TRANS_SETUP usage
 380          * and barriers
 381          */
 382         smp_rmb();
 383         if (root->last_trans == trans->transid &&
 384             !test_bit(BTRFS_ROOT_IN_TRANS_SETUP, &root->state))
 385                 return 0;
 386
 387         mutex_lock(&root->fs_info->reloc_mutex);
 388         record_root_in_trans(trans, root);
 389         mutex_unlock(&root->fs_info->reloc_mutex);
 390
 391         return 0;
 392 }
 393
 394 static inline int is_transaction_blocked(struct btrfs_transaction *trans)
 395 {
 396         return (trans->state >= TRANS_STATE_BLOCKED &&
 397                 trans->state < TRANS_STATE_UNBLOCKED &&
 398                 !trans->aborted);
 399 }
 400
 401 /* wait for commit against the current transaction to become unblocked
 402  * when this is done, it is safe to start a new transaction, but the current
 403  * transaction might not be fully on disk.
 404  */
 405 static void wait_current_trans(struct btrfs_root *root)
 406 {
 407         struct btrfs_transaction *cur_trans;
 408
 409         spin_lock(&root->fs_info->trans_lock);
 410         cur_trans = root->fs_info->running_transaction;
 411         if (cur_trans && is_transaction_blocked(cur_trans)) {
 412                 atomic_inc(&cur_trans->use_count);
 413                 spin_unlock(&root->fs_info->trans_lock);
 414
 415                 wait_event(root->fs_info->transaction_wait,
 416                            cur_trans->state >= TRANS_STATE_UNBLOCKED ||
 417                            cur_trans->aborted);
 418                 btrfs_put_transaction(cur_trans);
 419         } else {
 420                 spin_unlock(&root->fs_info->trans_lock);
 421         }
 422 }
 423
 424 static int may_wait_transaction(struct btrfs_root *root, int type)
 425 {
 426         if (root->fs_info->log_root_recovering)
 427                 return 0;
 428
 429         if (type == TRANS_USERSPACE)
 430                 return 1;
 431
 432         if (type == TRANS_START &&
 433             !atomic_read(&root->fs_info->open_ioctl_trans))
 434                 return 1;
 435
 436         return 0;
 437 }
 438
 439 static inline bool need_reserve_reloc_root(struct btrfs_root *root)
 440 {
 441         if (!root->fs_info->reloc_ctl ||
 442             !test_bit(BTRFS_ROOT_REF_COWS, &root->state) ||
 443             root->root_key.objectid == BTRFS_TREE_RELOC_OBJECTID ||
 444             root->reloc_root)
 445                 return false;
 446
 447         return true;
 448 }
 449
 450 static struct btrfs_trans_handle *
 451 start_transaction(struct btrfs_root *root, unsigned int num_items,
 452                   unsigned int type, enum btrfs_reserve_flush_enum flush)
 453 {
 454         struct btrfs_trans_handle *h;
 455         struct btrfs_transaction *cur_trans;
 456         u64 num_bytes = 0;
 457         u64 qgroup_reserved = 0;
 458         bool reloc_reserved = false;
 459         int ret;
 460
 461         /* Send isn't supposed to start transactions. */
 462         ASSERT(current->journal_info != BTRFS_SEND_TRANS_STUB);
 463
 464         if (test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state))
 465                 return ERR_PTR(-EROFS);
 466
 467         if (current->journal_info) {
 468                 WARN_ON(type & TRANS_EXTWRITERS);
 469                 h = current->journal_info;
 470                 h->use_count++;
 471                 WARN_ON(h->use_count > 2);
 472                 h->orig_rsv = h->block_rsv;
 473                 h->block_rsv = NULL;
 474                 goto got_it;
 475         }
 476
 477         /*
 478          * Do the reservation before we join the transaction so we can do all
 479          * the appropriate flushing if need be.
 480          */
 481         if (num_items > 0 && root != root->fs_info->chunk_root) {
 482                 qgroup_reserved = num_items * root->nodesize;
 483                 ret = btrfs_qgroup_reserve_meta(root, qgroup_reserved);
 484                 if (ret)
 485                         return ERR_PTR(ret);
 486
 487                 num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
 488                 /*
 489                  * Do the reservation for the relocation root creation
 490                  */
 491                 if (need_reserve_reloc_root(root)) {
 492                         num_bytes += root->nodesize;
 493                         reloc_reserved = true;
 494                 }
 495
 496                 ret = btrfs_block_rsv_add(root,
 497                                           &root->fs_info->trans_block_rsv,
 498                                           num_bytes, flush);
 499                 if (ret)
 500                         goto reserve_fail;
 501         }
 502 again:
 503         h = kmem_cache_zalloc(btrfs_trans_handle_cachep, GFP_NOFS);
 504         if (!h) {
 505                 ret = -ENOMEM;
 506                 goto alloc_fail;
 507         }
 508
 509         /*
 510          * If we are JOIN_NOLOCK we're already committing a transaction and
 511          * waiting on this guy, so we don't need to do the sb_start_intwrite
 512          * because we're already holding a ref.  We need this because we could
 513          * have raced in and did an fsync() on a file which can kick a commit
 514          * and then we deadlock with somebody doing a freeze.
 515          *
 516          * If we are ATTACH, it means we just want to catch the current
 517          * transaction and commit it, so we needn't do sb_start_intwrite().
 518          */
 519         if (type & __TRANS_FREEZABLE)
 520                 sb_start_intwrite(root->fs_info->sb);
 521
 522         if (may_wait_transaction(root, type))
 523                 wait_current_trans(root);
 524
 525         do {
 526                 ret = join_transaction(root, type);
 527                 if (ret == -EBUSY) {
 528                         wait_current_trans(root);
 529                         if (unlikely(type == TRANS_ATTACH))
 530                                 ret = -ENOENT;
 531                 }
 532         } while (ret == -EBUSY);
 533
 534         if (ret < 0) {
 535                 /* We must get the transaction if we are JOIN_NOLOCK. */
 536                 BUG_ON(type == TRANS_JOIN_NOLOCK);
 537                 goto join_fail;
 538         }
 539
 540         cur_trans = root->fs_info->running_transaction;
 541
 542         h->transid = cur_trans->transid;
 543         h->transaction = cur_trans;
 544         h->root = root;
 545         h->use_count = 1;
 546
 547         h->type = type;
 548         h->can_flush_pending_bgs = true;
 549         INIT_LIST_HEAD(&h->qgroup_ref_list);
 550         INIT_LIST_HEAD(&h->new_bgs);
 551
 552         smp_mb();
 553         if (cur_trans->state >= TRANS_STATE_BLOCKED &&
 554             may_wait_transaction(root, type)) {
 555                 current->journal_info = h;
 556                 btrfs_commit_transaction(h, root);
 557                 goto again;
 558         }
 559
 560         if (num_bytes) {
 561                 trace_btrfs_space_reservation(root->fs_info, "transaction",
 562                                               h->transid, num_bytes, 1);
 563                 h->block_rsv = &root->fs_info->trans_block_rsv;
 564                 h->bytes_reserved = num_bytes;
 565                 h->reloc_reserved = reloc_reserved;
 566         }
 567
 568 got_it:
 569         btrfs_record_root_in_trans(h, root);
 570
 571         if (!current->journal_info && type != TRANS_USERSPACE)
 572                 current->journal_info = h;
 573         return h;
 574
 575 join_fail:
 576         if (type & __TRANS_FREEZABLE)
 577                 sb_end_intwrite(root->fs_info->sb);
 578         kmem_cache_free(btrfs_trans_handle_cachep, h);
 579 alloc_fail:
 580         if (num_bytes)
 581                 btrfs_block_rsv_release(root, &root->fs_info->trans_block_rsv,
 582                                         num_bytes);
 583 reserve_fail:
 584         btrfs_qgroup_free_meta(root, qgroup_reserved);
 585         return ERR_PTR(ret);
 586 }
 587
 588 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 589                                                    unsigned int num_items)
 590 {
 591         return start_transaction(root, num_items, TRANS_START,
 592                                  BTRFS_RESERVE_FLUSH_ALL);
 593 }
 594 struct btrfs_trans_handle *btrfs_start_transaction_fallback_global_rsv(
 595                                         struct btrfs_root *root,
 596                                         unsigned int num_items,
 597                                         int min_factor)
 598 {
 599         struct btrfs_trans_handle *trans;
 600         u64 num_bytes;
 601         int ret;
 602
 603         trans = btrfs_start_transaction(root, num_items);
 604         if (!IS_ERR(trans) || PTR_ERR(trans) != -ENOSPC)
 605                 return trans;
 606
 607         trans = btrfs_start_transaction(root, 0);
 608         if (IS_ERR(trans))
 609                 return trans;
 610
 611         num_bytes = btrfs_calc_trans_metadata_size(root, num_items);
 612         ret = btrfs_cond_migrate_bytes(root->fs_info,
 613                                        &root->fs_info->trans_block_rsv,
 614                                        num_bytes,
 615                                        min_factor);
 616         if (ret) {
 617                 btrfs_end_transaction(trans, root);
 618                 return ERR_PTR(ret);
 619         }
 620
 621         trans->block_rsv = &root->fs_info->trans_block_rsv;
 622         trans->bytes_reserved = num_bytes;
 623
 624         return trans;
 625 }
 626
 627 struct btrfs_trans_handle *btrfs_start_transaction_lflush(
 628                                         struct btrfs_root *root,
 629                                         unsigned int num_items)
 630 {
 631         return start_transaction(root, num_items, TRANS_START,
 632                                  BTRFS_RESERVE_FLUSH_LIMIT);
 633 }
 634
 635 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 636 {
 637         return start_transaction(root, 0, TRANS_JOIN, 0);
 638 }
 639
 640 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
 641 {
 642         return start_transaction(root, 0, TRANS_JOIN_NOLOCK, 0);
 643 }
 644
 645 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 646 {
 647         return start_transaction(root, 0, TRANS_USERSPACE, 0);
 648 }
 649
 650 /*
 651  * btrfs_attach_transaction() - catch the running transaction
 652  *
 653  * It is used when we want to commit the current the transaction, but
 654  * don't want to start a new one.
 655  *
 656  * Note: If this function return -ENOENT, it just means there is no
 657  * running transaction. But it is possible that the inactive transaction
 658  * is still in the memory, not fully on disk. If you hope there is no
 659  * inactive transaction in the fs when -ENOENT is returned, you should
 660  * invoke
 661  *     btrfs_attach_transaction_barrier()
 662  */
 663 struct btrfs_trans_handle *btrfs_attach_transaction(struct btrfs_root *root)
 664 {
 665         return start_transaction(root, 0, TRANS_ATTACH, 0);
 666 }
 667
 668 /*
 669  * btrfs_attach_transaction_barrier() - catch the running transaction
 670  *
 671  * It is similar to the above function, the differentia is this one
 672  * will wait for all the inactive transactions until they fully
 673  * complete.
 674  */
 675 struct btrfs_trans_handle *
 676 btrfs_attach_transaction_barrier(struct btrfs_root *root)
 677 {
 678         struct btrfs_trans_handle *trans;
 679
 680         trans = start_transaction(root, 0, TRANS_ATTACH, 0);
 681         if (IS_ERR(trans) && PTR_ERR(trans) == -ENOENT)
 682                 btrfs_wait_for_commit(root, 0);
 683
 684         return trans;
 685 }
 686
 687 /* wait for a transaction commit to be fully complete */
 688 static noinline void wait_for_commit(struct btrfs_root *root,
 689                                     struct btrfs_transaction *commit)
 690 {
 691         wait_event(commit->commit_wait, commit->state == TRANS_STATE_COMPLETED);
 692 }
 693
 694 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 695 {
 696         struct btrfs_transaction *cur_trans = NULL, *t;
 697         int ret = 0;
 698
 699         if (transid) {
 700                 if (transid <= root->fs_info->last_trans_committed)
 701                         goto out;
 702
 703                 /* find specified transaction */
 704                 spin_lock(&root->fs_info->trans_lock);
 705                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 706                         if (t->transid == transid) {
 707                                 cur_trans = t;
 708                                 atomic_inc(&cur_trans->use_count);
 709                                 ret = 0;
 710                                 break;
 711                         }
 712                         if (t->transid > transid) {
 713                                 ret = 0;
 714                                 break;
 715                         }
 716                 }
 717                 spin_unlock(&root->fs_info->trans_lock);
 718
 719                 /*
 720                  * The specified transaction doesn't exist, or we
 721                  * raced with btrfs_commit_transaction
 722                  */
 723                 if (!cur_trans) {
 724                         if (transid > root->fs_info->last_trans_committed)
 725                                 ret = -EINVAL;
 726                         goto out;
 727                 }
 728         } else {
 729                 /* find newest transaction that is committing | committed */
 730                 spin_lock(&root->fs_info->trans_lock);
 731                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 732                                             list) {
 733                         if (t->state >= TRANS_STATE_COMMIT_START) {
 734                                 if (t->state == TRANS_STATE_COMPLETED)
 735                                         break;
 736                                 cur_trans = t;
 737                                 atomic_inc(&cur_trans->use_count);
 738                                 break;
 739                         }
 740                 }
 741                 spin_unlock(&root->fs_info->trans_lock);
 742                 if (!cur_trans)
 743                         goto out;  /* nothing committing|committed */
 744         }
 745
 746         wait_for_commit(root, cur_trans);
 747         btrfs_put_transaction(cur_trans);
 748 out:
 749         return ret;
 750 }
 751
 752 void btrfs_throttle(struct btrfs_root *root)
 753 {
 754         if (!atomic_read(&root->fs_info->open_ioctl_trans))
 755                 wait_current_trans(root);
 756 }
 757
 758 static int should_end_transaction(struct btrfs_trans_handle *trans,
 759                                   struct btrfs_root *root)
 760 {
 761         if (root->fs_info->global_block_rsv.space_info->full &&
 762             btrfs_check_space_for_delayed_refs(trans, root))
 763                 return 1;
 764
 765         return !!btrfs_block_rsv_check(root, &root->fs_info->global_block_rsv, 5);
 766 }
 767
 768 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 769                                  struct btrfs_root *root)
 770 {
 771         struct btrfs_transaction *cur_trans = trans->transaction;
 772         int updates;
 773         int err;
 774
 775         smp_mb();
 776         if (cur_trans->state >= TRANS_STATE_BLOCKED ||
 777             cur_trans->delayed_refs.flushing)
 778                 return 1;
 779
 780         updates = trans->delayed_ref_updates;
 781         trans->delayed_ref_updates = 0;
 782         if (updates) {
 783                 err = btrfs_run_delayed_refs(trans, root, updates * 2);
 784                 if (err) /* Error code will also eval true */
 785                         return err;
 786         }
 787
 788         return should_end_transaction(trans, root);
 789 }
 790
 791 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 792                           struct btrfs_root *root, int throttle)
 793 {
 794         struct btrfs_transaction *cur_trans = trans->transaction;
 795         struct btrfs_fs_info *info = root->fs_info;
 796         unsigned long cur = trans->delayed_ref_updates;
 797         int lock = (trans->type != TRANS_JOIN_NOLOCK);
 798         int err = 0;
 799         int must_run_delayed_refs = 0;
 800
 801         if (trans->use_count > 1) {
 802                 trans->use_count--;
 803                 trans->block_rsv = trans->orig_rsv;
 804                 return 0;
 805         }
 806
 807         btrfs_trans_release_metadata(trans, root);
 808         trans->block_rsv = NULL;
 809
 810         if (!list_empty(&trans->new_bgs))
 811                 btrfs_create_pending_block_groups(trans, root);
 812
 813         trans->delayed_ref_updates = 0;
 814         if (!trans->sync) {
 815                 must_run_delayed_refs =
 816                         btrfs_should_throttle_delayed_refs(trans, root);
 817                 cur = max_t(unsigned long, cur, 32);
 818
 819                 /*
 820                  * don't make the caller wait if they are from a NOLOCK
 821                  * or ATTACH transaction, it will deadlock with commit
 822                  */
 823                 if (must_run_delayed_refs == 1 &&
 824                     (trans->type & (__TRANS_JOIN_NOLOCK | __TRANS_ATTACH)))
 825                         must_run_delayed_refs = 2;
 826         }
 827
 828         btrfs_trans_release_metadata(trans, root);
 829         trans->block_rsv = NULL;
 830
 831         if (!list_empty(&trans->new_bgs))
 832                 btrfs_create_pending_block_groups(trans, root);
 833
 834         btrfs_trans_release_chunk_metadata(trans);
 835
 836         if (lock && !atomic_read(&root->fs_info->open_ioctl_trans) &&
 837             should_end_transaction(trans, root) &&
 838             ACCESS_ONCE(cur_trans->state) == TRANS_STATE_RUNNING) {
 839                 spin_lock(&info->trans_lock);
 840                 if (cur_trans->state == TRANS_STATE_RUNNING)
 841                         cur_trans->state = TRANS_STATE_BLOCKED;
 842                 spin_unlock(&info->trans_lock);
 843         }
 844
 845         if (lock && ACCESS_ONCE(cur_trans->state) == TRANS_STATE_BLOCKED) {
 846                 if (throttle)
 847                         return btrfs_commit_transaction(trans, root);
 848                 else
 849                         wake_up_process(info->transaction_kthread);
 850         }
 851
 852         if (trans->type & __TRANS_FREEZABLE)
 853                 sb_end_intwrite(root->fs_info->sb);
 854
 855         WARN_ON(cur_trans != info->running_transaction);
 856         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 857         atomic_dec(&cur_trans->num_writers);
 858         extwriter_counter_dec(cur_trans, trans->type);
 859
 860         /*
 861          * Make sure counter is updated before we wake up waiters.
 862          */
 863         smp_mb();
 864         if (waitqueue_active(&cur_trans->writer_wait))
 865                 wake_up(&cur_trans->writer_wait);
 866         btrfs_put_transaction(cur_trans);
 867
 868         if (current->journal_info == trans)
 869                 current->journal_info = NULL;
 870
 871         if (throttle)
 872                 btrfs_run_delayed_iputs(root);
 873
 874         if (trans->aborted ||
 875             test_bit(BTRFS_FS_STATE_ERROR, &root->fs_info->fs_state)) {
 876                 wake_up_process(info->transaction_kthread);
 877                 err = -EIO;
 878         }
 879         assert_qgroups_uptodate(trans);
 880
 881         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 882         if (must_run_delayed_refs) {
 883                 btrfs_async_run_delayed_refs(root, cur,
 884                                              must_run_delayed_refs == 1);
 885         }
 886         return err;
 887 }
 888
 889 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 890                           struct btrfs_root *root)
 891 {
 892         return __btrfs_end_transaction(trans, root, 0);
 893 }
 894
 895 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 896                                    struct btrfs_root *root)
 897 {
 898         return __btrfs_end_transaction(trans, root, 1);
 899 }
 900
 901 /*
 902  * when btree blocks are allocated, they have some corresponding bits set for
 903  * them in one of two extent_io trees.  This is used to make sure all of
 904  * those extents are sent to disk but does not wait on them
 905  */
 906 int btrfs_write_marked_extents(struct btrfs_root *root,
 907                                struct extent_io_tree *dirty_pages, int mark)
 908 {
 909         int err = 0;
 910         int werr = 0;
 911         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 912         struct extent_state *cached_state = NULL;
 913         u64 start = 0;
 914         u64 end;
 915
 916         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 917                                       mark, &cached_state)) {
 918                 bool wait_writeback = false;
 919
 920                 err = convert_extent_bit(dirty_pages, start, end,
 921                                          EXTENT_NEED_WAIT,
 922                                          mark, &cached_state, GFP_NOFS);
 923                 /*
 924                  * convert_extent_bit can return -ENOMEM, which is most of the
 925                  * time a temporary error. So when it happens, ignore the error
 926                  * and wait for writeback of this range to finish - because we
 927                  * failed to set the bit EXTENT_NEED_WAIT for the range, a call
 928                  * to btrfs_wait_marked_extents() would not know that writeback
 929                  * for this range started and therefore wouldn't wait for it to
 930                  * finish - we don't want to commit a superblock that points to
 931                  * btree nodes/leafs for which writeback hasn't finished yet
 932                  * (and without errors).
 933                  * We cleanup any entries left in the io tree when committing
 934                  * the transaction (through clear_btree_io_tree()).
 935                  */
 936                 if (err == -ENOMEM) {
 937                         err = 0;
 938                         wait_writeback = true;
 939                 }
 940                 if (!err)
 941                         err = filemap_fdatawrite_range(mapping, start, end);
 942                 if (err)
 943                         werr = err;
 944                 else if (wait_writeback)
 945                         werr = filemap_fdatawait_range(mapping, start, end);
 946                 free_extent_state(cached_state);
 947                 cached_state = NULL;
 948                 cond_resched();
 949                 start = end + 1;
 950         }
 951         return werr;
 952 }
 953
 954 /*
 955  * when btree blocks are allocated, they have some corresponding bits set for
 956  * them in one of two extent_io trees.  This is used to make sure all of
 957  * those extents are on disk for transaction or log commit.  We wait
 958  * on all the pages and clear them from the dirty pages state tree
 959  */
 960 int btrfs_wait_marked_extents(struct btrfs_root *root,
 961                               struct extent_io_tree *dirty_pages, int mark)
 962 {
 963         int err = 0;
 964         int werr = 0;
 965         struct address_space *mapping = root->fs_info->btree_inode->i_mapping;
 966         struct extent_state *cached_state = NULL;
 967         u64 start = 0;
 968         u64 end;
 969         struct btrfs_inode *btree_ino = BTRFS_I(root->fs_info->btree_inode);
 970         bool errors = false;
 971
 972         while (!find_first_extent_bit(dirty_pages, start, &start, &end,
 973                                       EXTENT_NEED_WAIT, &cached_state)) {
 974                 /*
 975                  * Ignore -ENOMEM errors returned by clear_extent_bit().
 976                  * When committing the transaction, we'll remove any entries
 977                  * left in the io tree. For a log commit, we don't remove them
 978                  * after committing the log because the tree can be accessed
 979                  * concurrently - we do it only at transaction commit time when
 980                  * it's safe to do it (through clear_btree_io_tree()).
 981                  */
 982                 err = clear_extent_bit(dirty_pages, start, end,
 983                                        EXTENT_NEED_WAIT,
 984                                        0, 0, &cached_state, GFP_NOFS);
 985                 if (err == -ENOMEM)
 986                         err = 0;
 987                 if (!err)
 988                         err = filemap_fdatawait_range(mapping, start, end);
 989                 if (err)
 990                         werr = err;
 991                 free_extent_state(cached_state);
 992                 cached_state = NULL;
 993                 cond_resched();
 994                 start = end + 1;
 995         }
 996         if (err)
 997                 werr = err;
 998
 999         if (root->root_key.objectid == BTRFS_TREE_LOG_OBJECTID) {
1000                 if ((mark & EXTENT_DIRTY) &&
1001                     test_and_clear_bit(BTRFS_INODE_BTREE_LOG1_ERR,
1002                                        &btree_ino->runtime_flags))
1003                         errors = true;
1004
1005                 if ((mark & EXTENT_NEW) &&
1006                     test_and_clear_bit(BTRFS_INODE_BTREE_LOG2_ERR,
1007                                        &btree_ino->runtime_flags))
1008                         errors = true;
1009         } else {
1010                 if (test_and_clear_bit(BTRFS_INODE_BTREE_ERR,
1011                                        &btree_ino->runtime_flags))
1012                         errors = true;
1013         }
1014
1015         if (errors && !werr)
1016                 werr = -EIO;
1017
1018         return werr;
1019 }
1020
1021 /*
1022  * when btree blocks are allocated, they have some corresponding bits set for
1023  * them in one of two extent_io trees.  This is used to make sure all of
1024  * those extents are on disk for transaction or log commit
1025  */
1026 static int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
1027                                 struct extent_io_tree *dirty_pages, int mark)
1028 {
1029         int ret;
1030         int ret2;
1031         struct blk_plug plug;
1032
1033         blk_start_plug(&plug);
1034         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
1035         blk_finish_plug(&plug);
1036         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
1037
1038         if (ret)
1039                 return ret;
1040         if (ret2)
1041                 return ret2;
1042         return 0;
1043 }
1044
1045 static int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
1046                                      struct btrfs_root *root)
1047 {
1048         int ret;
1049
1050         ret = btrfs_write_and_wait_marked_extents(root,
1051                                            &trans->transaction->dirty_pages,
1052                                            EXTENT_DIRTY);
1053         clear_btree_io_tree(&trans->transaction->dirty_pages);
1054
1055         return ret;
1056 }
1057
1058 /*
1059  * this is used to update the root pointer in the tree of tree roots.
1060  *
1061  * But, in the case of the extent allocation tree, updating the root
1062  * pointer may allocate blocks which may change the root of the extent
1063  * allocation tree.
1064  *
1065  * So, this loops and repeats and makes sure the cowonly root didn't
1066  * change while the root pointer was being updated in the metadata.
1067  */
1068 static int update_cowonly_root(struct btrfs_trans_handle *trans,
1069                                struct btrfs_root *root)
1070 {
1071         int ret;
1072         u64 old_root_bytenr;
1073         u64 old_root_used;
1074         struct btrfs_root *tree_root = root->fs_info->tree_root;
1075
1076         old_root_used = btrfs_root_used(&root->root_item);
1077
1078         while (1) {
1079                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
1080                 if (old_root_bytenr == root->node->start &&
1081                     old_root_used == btrfs_root_used(&root->root_item))
1082                         break;
1083
1084                 btrfs_set_root_node(&root->root_item, root->node);
1085                 ret = btrfs_update_root(trans, tree_root,
1086                                         &root->root_key,
1087                                         &root->root_item);
1088                 if (ret)
1089                         return ret;
1090
1091                 old_root_used = btrfs_root_used(&root->root_item);
1092         }
1093
1094         return 0;
1095 }
1096
1097 /*
1098  * update all the cowonly tree roots on disk
1099  *
1100  * The error handling in this function may not be obvious. Any of the
1101  * failures will cause the file system to go offline. We still need
1102  * to clean up the delayed refs.
1103  */
1104 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
1105                                          struct btrfs_root *root)
1106 {
1107         struct btrfs_fs_info *fs_info = root->fs_info;
1108         struct list_head *dirty_bgs = &trans->transaction->dirty_bgs;
1109         struct list_head *io_bgs = &trans->transaction->io_bgs;
1110         struct list_head *next;
1111         struct extent_buffer *eb;
1112         int ret;
1113
1114         eb = btrfs_lock_root_node(fs_info->tree_root);
1115         ret = btrfs_cow_block(trans, fs_info->tree_root, eb, NULL,
1116                               0, &eb);
1117         btrfs_tree_unlock(eb);
1118         free_extent_buffer(eb);
1119
1120         if (ret)
1121                 return ret;
1122
1123         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1124         if (ret)
1125                 return ret;
1126
1127         ret = btrfs_run_dev_stats(trans, root->fs_info);
1128         if (ret)
1129                 return ret;
1130         ret = btrfs_run_dev_replace(trans, root->fs_info);
1131         if (ret)
1132                 return ret;
1133         ret = btrfs_run_qgroups(trans, root->fs_info);
1134         if (ret)
1135                 return ret;
1136
1137         ret = btrfs_setup_space_cache(trans, root);
1138         if (ret)
1139                 return ret;
1140
1141         /* run_qgroups might have added some more refs */
1142         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1143         if (ret)
1144                 return ret;
1145 again:
1146         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
1147                 next = fs_info->dirty_cowonly_roots.next;
1148                 list_del_init(next);
1149                 root = list_entry(next, struct btrfs_root, dirty_list);
1150                 clear_bit(BTRFS_ROOT_DIRTY, &root->state);
1151
1152                 if (root != fs_info->extent_root)
1153                         list_add_tail(&root->dirty_list,
1154                                       &trans->transaction->switch_commits);
1155                 ret = update_cowonly_root(trans, root);
1156                 if (ret)
1157                         return ret;
1158                 ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1159                 if (ret)
1160                         return ret;
1161         }
1162
1163         while (!list_empty(dirty_bgs) || !list_empty(io_bgs)) {
1164                 ret = btrfs_write_dirty_block_groups(trans, root);
1165                 if (ret)
1166                         return ret;
1167                 ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1168                 if (ret)
1169                         return ret;
1170         }
1171
1172         if (!list_empty(&fs_info->dirty_cowonly_roots))
1173                 goto again;
1174
1175         list_add_tail(&fs_info->extent_root->dirty_list,
1176                       &trans->transaction->switch_commits);
1177         btrfs_after_dev_replace_commit(fs_info);
1178
1179         return 0;
1180 }
1181
1182 /*
1183  * dead roots are old snapshots that need to be deleted.  This allocates
1184  * a dirty root struct and adds it into the list of dead roots that need to
1185  * be deleted
1186  */
1187 void btrfs_add_dead_root(struct btrfs_root *root)
1188 {
1189         spin_lock(&root->fs_info->trans_lock);
1190         if (list_empty(&root->root_list))
1191                 list_add_tail(&root->root_list, &root->fs_info->dead_roots);
1192         spin_unlock(&root->fs_info->trans_lock);
1193 }
1194
1195 /*
1196  * update all the cowonly tree roots on disk
1197  */
1198 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
1199                                     struct btrfs_root *root)
1200 {
1201         struct btrfs_root *gang[8];
1202         struct btrfs_fs_info *fs_info = root->fs_info;
1203         int i;
1204         int ret;
1205         int err = 0;
1206
1207         spin_lock(&fs_info->fs_roots_radix_lock);
1208         while (1) {
1209                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
1210                                                  (void **)gang, 0,
1211                                                  ARRAY_SIZE(gang),
1212                                                  BTRFS_ROOT_TRANS_TAG);
1213                 if (ret == 0)
1214                         break;
1215                 for (i = 0; i < ret; i++) {
1216                         root = gang[i];
1217                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
1218                                         (unsigned long)root->root_key.objectid,
1219                                         BTRFS_ROOT_TRANS_TAG);
1220                         spin_unlock(&fs_info->fs_roots_radix_lock);
1221
1222                         btrfs_free_log(trans, root);
1223                         btrfs_update_reloc_root(trans, root);
1224                         btrfs_orphan_commit_root(trans, root);
1225
1226                         btrfs_save_ino_cache(root, trans);
1227
1228                         /* see comments in should_cow_block() */
1229                         clear_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1230                         smp_mb__after_atomic();
1231
1232                         if (root->commit_root != root->node) {
1233                                 list_add_tail(&root->dirty_list,
1234                                         &trans->transaction->switch_commits);
1235                                 btrfs_set_root_node(&root->root_item,
1236                                                     root->node);
1237                         }
1238
1239                         err = btrfs_update_root(trans, fs_info->tree_root,
1240                                                 &root->root_key,
1241                                                 &root->root_item);
1242                         spin_lock(&fs_info->fs_roots_radix_lock);
1243                         if (err)
1244                                 break;
1245                         btrfs_qgroup_free_meta_all(root);
1246                 }
1247         }
1248         spin_unlock(&fs_info->fs_roots_radix_lock);
1249         return err;
1250 }
1251
1252 /*
1253  * defrag a given btree.
1254  * Every leaf in the btree is read and defragged.
1255  */
1256 int btrfs_defrag_root(struct btrfs_root *root)
1257 {
1258         struct btrfs_fs_info *info = root->fs_info;
1259         struct btrfs_trans_handle *trans;
1260         int ret;
1261
1262         if (test_and_set_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state))
1263                 return 0;
1264
1265         while (1) {
1266                 trans = btrfs_start_transaction(root, 0);
1267                 if (IS_ERR(trans))
1268                         return PTR_ERR(trans);
1269
1270                 ret = btrfs_defrag_leaves(trans, root);
1271
1272                 btrfs_end_transaction(trans, root);
1273                 btrfs_btree_balance_dirty(info->tree_root);
1274                 cond_resched();
1275
1276                 if (btrfs_fs_closing(root->fs_info) || ret != -EAGAIN)
1277                         break;
1278
1279                 if (btrfs_defrag_cancelled(root->fs_info)) {
1280                         pr_debug("BTRFS: defrag_root cancelled\n");
1281                         ret = -EAGAIN;
1282                         break;
1283                 }
1284         }
1285         clear_bit(BTRFS_ROOT_DEFRAG_RUNNING, &root->state);
1286         return ret;
1287 }
1288
1289 /*
1290  * new snapshots need to be created at a very specific time in the
1291  * transaction commit.  This does the actual creation.
1292  *
1293  * Note:
1294  * If the error which may affect the commitment of the current transaction
1295  * happens, we should return the error number. If the error which just affect
1296  * the creation of the pending snapshots, just return 0.
1297  */
1298 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
1299                                    struct btrfs_fs_info *fs_info,
1300                                    struct btrfs_pending_snapshot *pending)
1301 {
1302         struct btrfs_key key;
1303         struct btrfs_root_item *new_root_item;
1304         struct btrfs_root *tree_root = fs_info->tree_root;
1305         struct btrfs_root *root = pending->root;
1306         struct btrfs_root *parent_root;
1307         struct btrfs_block_rsv *rsv;
1308         struct inode *parent_inode;
1309         struct btrfs_path *path;
1310         struct btrfs_dir_item *dir_item;
1311         struct dentry *dentry;
1312         struct extent_buffer *tmp;
1313         struct extent_buffer *old;
1314         struct timespec cur_time = CURRENT_TIME;
1315         int ret = 0;
1316         u64 to_reserve = 0;
1317         u64 index = 0;
1318         u64 objectid;
1319         u64 root_flags;
1320         uuid_le new_uuid;
1321
1322         path = btrfs_alloc_path();
1323         if (!path) {
1324                 pending->error = -ENOMEM;
1325                 return 0;
1326         }
1327
1328         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
1329         if (!new_root_item) {
1330                 pending->error = -ENOMEM;
1331                 goto root_item_alloc_fail;
1332         }
1333
1334         pending->error = btrfs_find_free_objectid(tree_root, &objectid);
1335         if (pending->error)
1336                 goto no_free_objectid;
1337
1338         /*
1339          * Make qgroup to skip current new snapshot's qgroupid, as it is
1340          * accounted by later btrfs_qgroup_inherit().
1341          */
1342         btrfs_set_skip_qgroup(trans, objectid);
1343
1344         btrfs_reloc_pre_snapshot(pending, &to_reserve);
1345
1346         if (to_reserve > 0) {
1347                 pending->error = btrfs_block_rsv_add(root,
1348                                                      &pending->block_rsv,
1349                                                      to_reserve,
1350                                                      BTRFS_RESERVE_NO_FLUSH);
1351                 if (pending->error)
1352                         goto clear_skip_qgroup;
1353         }
1354
1355         key.objectid = objectid;
1356         key.offset = (u64)-1;
1357         key.type = BTRFS_ROOT_ITEM_KEY;
1358
1359         rsv = trans->block_rsv;
1360         trans->block_rsv = &pending->block_rsv;
1361         trans->bytes_reserved = trans->block_rsv->reserved;
1362
1363         dentry = pending->dentry;
1364         parent_inode = pending->dir;
1365         parent_root = BTRFS_I(parent_inode)->root;
1366         record_root_in_trans(trans, parent_root);
1367
1368         /*
1369          * insert the directory item
1370          */
1371         ret = btrfs_set_inode_index(parent_inode, &index);
1372         BUG_ON(ret); /* -ENOMEM */
1373
1374         /* check if there is a file/dir which has the same name. */
1375         dir_item = btrfs_lookup_dir_item(NULL, parent_root, path,
1376                                          btrfs_ino(parent_inode),
1377                                          dentry->d_name.name,
1378                                          dentry->d_name.len, 0);
1379         if (dir_item != NULL && !IS_ERR(dir_item)) {
1380                 pending->error = -EEXIST;
1381                 goto dir_item_existed;
1382         } else if (IS_ERR(dir_item)) {
1383                 ret = PTR_ERR(dir_item);
1384                 btrfs_abort_transaction(trans, root, ret);
1385                 goto fail;
1386         }
1387         btrfs_release_path(path);
1388
1389         /*
1390          * pull in the delayed directory update
1391          * and the delayed inode item
1392          * otherwise we corrupt the FS during
1393          * snapshot
1394          */
1395         ret = btrfs_run_delayed_items(trans, root);
1396         if (ret) {      /* Transaction aborted */
1397                 btrfs_abort_transaction(trans, root, ret);
1398                 goto fail;
1399         }
1400
1401         record_root_in_trans(trans, root);
1402         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
1403         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
1404         btrfs_check_and_init_root_item(new_root_item);
1405
1406         root_flags = btrfs_root_flags(new_root_item);
1407         if (pending->readonly)
1408                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1409         else
1410                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1411         btrfs_set_root_flags(new_root_item, root_flags);
1412
1413         btrfs_set_root_generation_v2(new_root_item,
1414                         trans->transid);
1415         uuid_le_gen(&new_uuid);
1416         memcpy(new_root_item->uuid, new_uuid.b, BTRFS_UUID_SIZE);
1417         memcpy(new_root_item->parent_uuid, root->root_item.uuid,
1418                         BTRFS_UUID_SIZE);
1419         if (!(root_flags & BTRFS_ROOT_SUBVOL_RDONLY)) {
1420                 memset(new_root_item->received_uuid, 0,
1421                        sizeof(new_root_item->received_uuid));
1422                 memset(&new_root_item->stime, 0, sizeof(new_root_item->stime));
1423                 memset(&new_root_item->rtime, 0, sizeof(new_root_item->rtime));
1424                 btrfs_set_root_stransid(new_root_item, 0);
1425                 btrfs_set_root_rtransid(new_root_item, 0);
1426         }
1427         btrfs_set_stack_timespec_sec(&new_root_item->otime, cur_time.tv_sec);
1428         btrfs_set_stack_timespec_nsec(&new_root_item->otime, cur_time.tv_nsec);
1429         btrfs_set_root_otransid(new_root_item, trans->transid);
1430
1431         old = btrfs_lock_root_node(root);
1432         ret = btrfs_cow_block(trans, root, old, NULL, 0, &old);
1433         if (ret) {
1434                 btrfs_tree_unlock(old);
1435                 free_extent_buffer(old);
1436                 btrfs_abort_transaction(trans, root, ret);
1437                 goto fail;
1438         }
1439
1440         btrfs_set_lock_blocking(old);
1441
1442         ret = btrfs_copy_root(trans, root, old, &tmp, objectid);
1443         /* clean up in any case */
1444         btrfs_tree_unlock(old);
1445         free_extent_buffer(old);
1446         if (ret) {
1447                 btrfs_abort_transaction(trans, root, ret);
1448                 goto fail;
1449         }
1450         /* see comments in should_cow_block() */
1451         set_bit(BTRFS_ROOT_FORCE_COW, &root->state);
1452         smp_wmb();
1453
1454         btrfs_set_root_node(new_root_item, tmp);
1455         /* record when the snapshot was created in key.offset */
1456         key.offset = trans->transid;
1457         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1458         btrfs_tree_unlock(tmp);
1459         free_extent_buffer(tmp);
1460         if (ret) {
1461                 btrfs_abort_transaction(trans, root, ret);
1462                 goto fail;
1463         }
1464
1465         /*
1466          * insert root back/forward references
1467          */
1468         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1469                                  parent_root->root_key.objectid,
1470                                  btrfs_ino(parent_inode), index,
1471                                  dentry->d_name.name, dentry->d_name.len);
1472         if (ret) {
1473                 btrfs_abort_transaction(trans, root, ret);
1474                 goto fail;
1475         }
1476
1477         key.offset = (u64)-1;
1478         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1479         if (IS_ERR(pending->snap)) {
1480                 ret = PTR_ERR(pending->snap);
1481                 btrfs_abort_transaction(trans, root, ret);
1482                 goto fail;
1483         }
1484
1485         ret = btrfs_reloc_post_snapshot(trans, pending);
1486         if (ret) {
1487                 btrfs_abort_transaction(trans, root, ret);
1488                 goto fail;
1489         }
1490
1491         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1492         if (ret) {
1493                 btrfs_abort_transaction(trans, root, ret);
1494                 goto fail;
1495         }
1496
1497         ret = btrfs_insert_dir_item(trans, parent_root,
1498                                     dentry->d_name.name, dentry->d_name.len,
1499                                     parent_inode, &key,
1500                                     BTRFS_FT_DIR, index);
1501         /* We have check then name at the beginning, so it is impossible. */
1502         BUG_ON(ret == -EEXIST || ret == -EOVERFLOW);
1503         if (ret) {
1504                 btrfs_abort_transaction(trans, root, ret);
1505                 goto fail;
1506         }
1507
1508         btrfs_i_size_write(parent_inode, parent_inode->i_size +
1509                                          dentry->d_name.len * 2);
1510         parent_inode->i_mtime = parent_inode->i_ctime = CURRENT_TIME;
1511         ret = btrfs_update_inode_fallback(trans, parent_root, parent_inode);
1512         if (ret) {
1513                 btrfs_abort_transaction(trans, root, ret);
1514                 goto fail;
1515         }
1516         ret = btrfs_uuid_tree_add(trans, fs_info->uuid_root, new_uuid.b,
1517                                   BTRFS_UUID_KEY_SUBVOL, objectid);
1518         if (ret) {
1519                 btrfs_abort_transaction(trans, root, ret);
1520                 goto fail;
1521         }
1522         if (!btrfs_is_empty_uuid(new_root_item->received_uuid)) {
1523                 ret = btrfs_uuid_tree_add(trans, fs_info->uuid_root,
1524                                           new_root_item->received_uuid,
1525                                           BTRFS_UUID_KEY_RECEIVED_SUBVOL,
1526                                           objectid);
1527                 if (ret && ret != -EEXIST) {
1528                         btrfs_abort_transaction(trans, root, ret);
1529                         goto fail;
1530                 }
1531         }
1532
1533         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1534         if (ret) {
1535                 btrfs_abort_transaction(trans, root, ret);
1536                 goto fail;
1537         }
1538
1539         /*
1540          * account qgroup counters before qgroup_inherit()
1541          */
1542         ret = btrfs_qgroup_prepare_account_extents(trans, fs_info);
1543         if (ret)
1544                 goto fail;
1545         ret = btrfs_qgroup_account_extents(trans, fs_info);
1546         if (ret)
1547                 goto fail;
1548         ret = btrfs_qgroup_inherit(trans, fs_info,
1549                                    root->root_key.objectid,
1550                                    objectid, pending->inherit);
1551         if (ret) {
1552                 btrfs_abort_transaction(trans, root, ret);
1553                 goto fail;
1554         }
1555
1556 fail:
1557         pending->error = ret;
1558 dir_item_existed:
1559         trans->block_rsv = rsv;
1560         trans->bytes_reserved = 0;
1561 clear_skip_qgroup:
1562         btrfs_clear_skip_qgroup(trans);
1563 no_free_objectid:
1564         kfree(new_root_item);
1565 root_item_alloc_fail:
1566         btrfs_free_path(path);
1567         return ret;
1568 }
1569
1570 /*
1571  * create all the snapshots we've scheduled for creation
1572  */
1573 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1574                                              struct btrfs_fs_info *fs_info)
1575 {
1576         struct btrfs_pending_snapshot *pending, *next;
1577         struct list_head *head = &trans->transaction->pending_snapshots;
1578         int ret = 0;
1579
1580         list_for_each_entry_safe(pending, next, head, list) {
1581                 list_del(&pending->list);
1582                 ret = create_pending_snapshot(trans, fs_info, pending);
1583                 if (ret)
1584                         break;
1585         }
1586         return ret;
1587 }
1588
1589 static void update_super_roots(struct btrfs_root *root)
1590 {
1591         struct btrfs_root_item *root_item;
1592         struct btrfs_super_block *super;
1593
1594         super = root->fs_info->super_copy;
1595
1596         root_item = &root->fs_info->chunk_root->root_item;
1597         super->chunk_root = root_item->bytenr;
1598         super->chunk_root_generation = root_item->generation;
1599         super->chunk_root_level = root_item->level;
1600
1601         root_item = &root->fs_info->tree_root->root_item;
1602         super->root = root_item->bytenr;
1603         super->generation = root_item->generation;
1604         super->root_level = root_item->level;
1605         if (btrfs_test_opt(root, SPACE_CACHE))
1606                 super->cache_generation = root_item->generation;
1607         if (root->fs_info->update_uuid_tree_gen)
1608                 super->uuid_tree_generation = root_item->generation;
1609 }
1610
1611 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1612 {
1613         struct btrfs_transaction *trans;
1614         int ret = 0;
1615
1616         spin_lock(&info->trans_lock);
1617         trans = info->running_transaction;
1618         if (trans)
1619                 ret = (trans->state >= TRANS_STATE_COMMIT_START);
1620         spin_unlock(&info->trans_lock);
1621         return ret;
1622 }
1623
1624 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1625 {
1626         struct btrfs_transaction *trans;
1627         int ret = 0;
1628
1629         spin_lock(&info->trans_lock);
1630         trans = info->running_transaction;
1631         if (trans)
1632                 ret = is_transaction_blocked(trans);
1633         spin_unlock(&info->trans_lock);
1634         return ret;
1635 }
1636
1637 /*
1638  * wait for the current transaction commit to start and block subsequent
1639  * transaction joins
1640  */
1641 static void wait_current_trans_commit_start(struct btrfs_root *root,
1642                                             struct btrfs_transaction *trans)
1643 {
1644         wait_event(root->fs_info->transaction_blocked_wait,
1645                    trans->state >= TRANS_STATE_COMMIT_START ||
1646                    trans->aborted);
1647 }
1648
1649 /*
1650  * wait for the current transaction to start and then become unblocked.
1651  * caller holds ref.
1652  */
1653 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1654                                          struct btrfs_transaction *trans)
1655 {
1656         wait_event(root->fs_info->transaction_wait,
1657                    trans->state >= TRANS_STATE_UNBLOCKED ||
1658                    trans->aborted);
1659 }
1660
1661 /*
1662  * commit transactions asynchronously. once btrfs_commit_transaction_async
1663  * returns, any subsequent transaction will not be allowed to join.
1664  */
1665 struct btrfs_async_commit {
1666         struct btrfs_trans_handle *newtrans;
1667         struct btrfs_root *root;
1668         struct work_struct work;
1669 };
1670
1671 static void do_async_commit(struct work_struct *work)
1672 {
1673         struct btrfs_async_commit *ac =
1674                 container_of(work, struct btrfs_async_commit, work);
1675
1676         /*
1677          * We've got freeze protection passed with the transaction.
1678          * Tell lockdep about it.
1679          */
1680         if (ac->newtrans->type & __TRANS_FREEZABLE)
1681                 __sb_writers_acquired(ac->root->fs_info->sb, SB_FREEZE_FS);
1682
1683         current->journal_info = ac->newtrans;
1684
1685         btrfs_commit_transaction(ac->newtrans, ac->root);
1686         kfree(ac);
1687 }
1688
1689 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1690                                    struct btrfs_root *root,
1691                                    int wait_for_unblock)
1692 {
1693         struct btrfs_async_commit *ac;
1694         struct btrfs_transaction *cur_trans;
1695
1696         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1697         if (!ac)
1698                 return -ENOMEM;
1699
1700         INIT_WORK(&ac->work, do_async_commit);
1701         ac->root = root;
1702         ac->newtrans = btrfs_join_transaction(root);
1703         if (IS_ERR(ac->newtrans)) {
1704                 int err = PTR_ERR(ac->newtrans);
1705                 kfree(ac);
1706                 return err;
1707         }
1708
1709         /* take transaction reference */
1710         cur_trans = trans->transaction;
1711         atomic_inc(&cur_trans->use_count);
1712
1713         btrfs_end_transaction(trans, root);
1714
1715         /*
1716          * Tell lockdep we've released the freeze rwsem, since the
1717          * async commit thread will be the one to unlock it.
1718          */
1719         if (ac->newtrans->type & __TRANS_FREEZABLE)
1720                 __sb_writers_release(root->fs_info->sb, SB_FREEZE_FS);
1721
1722         schedule_work(&ac->work);
1723
1724         /* wait for transaction to start and unblock */
1725         if (wait_for_unblock)
1726                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1727         else
1728                 wait_current_trans_commit_start(root, cur_trans);
1729
1730         if (current->journal_info == trans)
1731                 current->journal_info = NULL;
1732
1733         btrfs_put_transaction(cur_trans);
1734         return 0;
1735 }
1736
1737
1738 static void cleanup_transaction(struct btrfs_trans_handle *trans,
1739                                 struct btrfs_root *root, int err)
1740 {
1741         struct btrfs_transaction *cur_trans = trans->transaction;
1742         DEFINE_WAIT(wait);
1743
1744         WARN_ON(trans->use_count > 1);
1745
1746         btrfs_abort_transaction(trans, root, err);
1747
1748         spin_lock(&root->fs_info->trans_lock);
1749
1750         /*
1751          * If the transaction is removed from the list, it means this
1752          * transaction has been committed successfully, so it is impossible
1753          * to call the cleanup function.
1754          */
1755         BUG_ON(list_empty(&cur_trans->list));
1756
1757         list_del_init(&cur_trans->list);
1758         if (cur_trans == root->fs_info->running_transaction) {
1759                 cur_trans->state = TRANS_STATE_COMMIT_DOING;
1760                 spin_unlock(&root->fs_info->trans_lock);
1761                 wait_event(cur_trans->writer_wait,
1762                            atomic_read(&cur_trans->num_writers) == 1);
1763
1764                 spin_lock(&root->fs_info->trans_lock);
1765         }
1766         spin_unlock(&root->fs_info->trans_lock);
1767
1768         btrfs_cleanup_one_transaction(trans->transaction, root);
1769
1770         spin_lock(&root->fs_info->trans_lock);
1771         if (cur_trans == root->fs_info->running_transaction)
1772                 root->fs_info->running_transaction = NULL;
1773         spin_unlock(&root->fs_info->trans_lock);
1774
1775         if (trans->type & __TRANS_FREEZABLE)
1776                 sb_end_intwrite(root->fs_info->sb);
1777         btrfs_put_transaction(cur_trans);
1778         btrfs_put_transaction(cur_trans);
1779
1780         trace_btrfs_transaction_commit(root);
1781
1782         if (current->journal_info == trans)
1783                 current->journal_info = NULL;
1784         btrfs_scrub_cancel(root->fs_info);
1785
1786         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1787 }
1788
1789 static inline int btrfs_start_delalloc_flush(struct btrfs_fs_info *fs_info)
1790 {
1791         if (btrfs_test_opt(fs_info->tree_root, FLUSHONCOMMIT))
1792                 return btrfs_start_delalloc_roots(fs_info, 1, -1);
1793         return 0;
1794 }
1795
1796 static inline void btrfs_wait_delalloc_flush(struct btrfs_fs_info *fs_info)
1797 {
1798         if (btrfs_test_opt(fs_info->tree_root, FLUSHONCOMMIT))
1799                 btrfs_wait_ordered_roots(fs_info, -1);
1800 }
1801
1802 static inline void
1803 btrfs_wait_pending_ordered(struct btrfs_transaction *cur_trans)
1804 {
1805         wait_event(cur_trans->pending_wait,
1806                    atomic_read(&cur_trans->pending_ordered) == 0);
1807 }
1808
1809 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1810                              struct btrfs_root *root)
1811 {
1812         struct btrfs_transaction *cur_trans = trans->transaction;
1813         struct btrfs_transaction *prev_trans = NULL;
1814         struct btrfs_inode *btree_ino = BTRFS_I(root->fs_info->btree_inode);
1815         int ret;
1816
1817         /* Stop the commit early if ->aborted is set */
1818         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1819                 ret = cur_trans->aborted;
1820                 btrfs_end_transaction(trans, root);
1821                 return ret;
1822         }
1823
1824         /* make a pass through all the delayed refs we have so far
1825          * any runnings procs may add more while we are here
1826          */
1827         ret = btrfs_run_delayed_refs(trans, root, 0);
1828         if (ret) {
1829                 btrfs_end_transaction(trans, root);
1830                 return ret;
1831         }
1832
1833         btrfs_trans_release_metadata(trans, root);
1834         trans->block_rsv = NULL;
1835
1836         cur_trans = trans->transaction;
1837
1838         /*
1839          * set the flushing flag so procs in this transaction have to
1840          * start sending their work down.
1841          */
1842         cur_trans->delayed_refs.flushing = 1;
1843         smp_wmb();
1844
1845         if (!list_empty(&trans->new_bgs))
1846                 btrfs_create_pending_block_groups(trans, root);
1847
1848         ret = btrfs_run_delayed_refs(trans, root, 0);
1849         if (ret) {
1850                 btrfs_end_transaction(trans, root);
1851                 return ret;
1852         }
1853
1854         if (!test_bit(BTRFS_TRANS_DIRTY_BG_RUN, &cur_trans->flags)) {
1855                 int run_it = 0;
1856
1857                 /* this mutex is also taken before trying to set
1858                  * block groups readonly.  We need to make sure
1859                  * that nobody has set a block group readonly
1860                  * after a extents from that block group have been
1861                  * allocated for cache files.  btrfs_set_block_group_ro
1862                  * will wait for the transaction to commit if it
1863                  * finds BTRFS_TRANS_DIRTY_BG_RUN set.
1864                  *
1865                  * The BTRFS_TRANS_DIRTY_BG_RUN flag is also used to make sure
1866                  * only one process starts all the block group IO.  It wouldn't
1867                  * hurt to have more than one go through, but there's no
1868                  * real advantage to it either.
1869                  */
1870                 mutex_lock(&root->fs_info->ro_block_group_mutex);
1871                 if (!test_and_set_bit(BTRFS_TRANS_DIRTY_BG_RUN,
1872                                       &cur_trans->flags))
1873                         run_it = 1;
1874                 mutex_unlock(&root->fs_info->ro_block_group_mutex);
1875
1876                 if (run_it)
1877                         ret = btrfs_start_dirty_block_groups(trans, root);
1878         }
1879         if (ret) {
1880                 btrfs_end_transaction(trans, root);
1881                 return ret;
1882         }
1883
1884         spin_lock(&root->fs_info->trans_lock);
1885         if (cur_trans->state >= TRANS_STATE_COMMIT_START) {
1886                 spin_unlock(&root->fs_info->trans_lock);
1887                 atomic_inc(&cur_trans->use_count);
1888                 ret = btrfs_end_transaction(trans, root);
1889
1890                 wait_for_commit(root, cur_trans);
1891
1892                 if (unlikely(cur_trans->aborted))
1893                         ret = cur_trans->aborted;
1894
1895                 btrfs_put_transaction(cur_trans);
1896
1897                 return ret;
1898         }
1899
1900         cur_trans->state = TRANS_STATE_COMMIT_START;
1901         wake_up(&root->fs_info->transaction_blocked_wait);
1902
1903         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1904                 prev_trans = list_entry(cur_trans->list.prev,
1905                                         struct btrfs_transaction, list);
1906                 if (prev_trans->state != TRANS_STATE_COMPLETED) {
1907                         atomic_inc(&prev_trans->use_count);
1908                         spin_unlock(&root->fs_info->trans_lock);
1909
1910                         wait_for_commit(root, prev_trans);
1911                         ret = prev_trans->aborted;
1912
1913                         btrfs_put_transaction(prev_trans);
1914                         if (ret)
1915                                 goto cleanup_transaction;
1916                 } else {
1917                         spin_unlock(&root->fs_info->trans_lock);
1918                 }
1919         } else {
1920                 spin_unlock(&root->fs_info->trans_lock);
1921         }
1922
1923         extwriter_counter_dec(cur_trans, trans->type);
1924
1925         ret = btrfs_start_delalloc_flush(root->fs_info);
1926         if (ret)
1927                 goto cleanup_transaction;
1928
1929         ret = btrfs_run_delayed_items(trans, root);
1930         if (ret)
1931                 goto cleanup_transaction;
1932
1933         wait_event(cur_trans->writer_wait,
1934                    extwriter_counter_read(cur_trans) == 0);
1935
1936         /* some pending stuffs might be added after the previous flush. */
1937         ret = btrfs_run_delayed_items(trans, root);
1938         if (ret)
1939                 goto cleanup_transaction;
1940
1941         btrfs_wait_delalloc_flush(root->fs_info);
1942
1943         btrfs_wait_pending_ordered(cur_trans);
1944
1945         btrfs_scrub_pause(root);
1946         /*
1947          * Ok now we need to make sure to block out any other joins while we
1948          * commit the transaction.  We could have started a join before setting
1949          * COMMIT_DOING so make sure to wait for num_writers to == 1 again.
1950          */
1951         spin_lock(&root->fs_info->trans_lock);
1952         cur_trans->state = TRANS_STATE_COMMIT_DOING;
1953         spin_unlock(&root->fs_info->trans_lock);
1954         wait_event(cur_trans->writer_wait,
1955                    atomic_read(&cur_trans->num_writers) == 1);
1956
1957         /* ->aborted might be set after the previous check, so check it */
1958         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
1959                 ret = cur_trans->aborted;
1960                 goto scrub_continue;
1961         }
1962         /*
1963          * the reloc mutex makes sure that we stop
1964          * the balancing code from coming in and moving
1965          * extents around in the middle of the commit
1966          */
1967         mutex_lock(&root->fs_info->reloc_mutex);
1968
1969         /*
1970          * We needn't worry about the delayed items because we will
1971          * deal with them in create_pending_snapshot(), which is the
1972          * core function of the snapshot creation.
1973          */
1974         ret = create_pending_snapshots(trans, root->fs_info);
1975         if (ret) {
1976                 mutex_unlock(&root->fs_info->reloc_mutex);
1977                 goto scrub_continue;
1978         }
1979
1980         /*
1981          * We insert the dir indexes of the snapshots and update the inode
1982          * of the snapshots' parents after the snapshot creation, so there
1983          * are some delayed items which are not dealt with. Now deal with
1984          * them.
1985          *
1986          * We needn't worry that this operation will corrupt the snapshots,
1987          * because all the tree which are snapshoted will be forced to COW
1988          * the nodes and leaves.
1989          */
1990         ret = btrfs_run_delayed_items(trans, root);
1991         if (ret) {
1992                 mutex_unlock(&root->fs_info->reloc_mutex);
1993                 goto scrub_continue;
1994         }
1995
1996         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1997         if (ret) {
1998                 mutex_unlock(&root->fs_info->reloc_mutex);
1999                 goto scrub_continue;
2000         }
2001
2002         /* Reocrd old roots for later qgroup accounting */
2003         ret = btrfs_qgroup_prepare_account_extents(trans, root->fs_info);
2004         if (ret) {
2005                 mutex_unlock(&root->fs_info->reloc_mutex);
2006                 goto scrub_continue;
2007         }
2008
2009         /*
2010          * make sure none of the code above managed to slip in a
2011          * delayed item
2012          */
2013         btrfs_assert_delayed_root_empty(root);
2014
2015         WARN_ON(cur_trans != trans->transaction);
2016
2017         /* btrfs_commit_tree_roots is responsible for getting the
2018          * various roots consistent with each other.  Every pointer
2019          * in the tree of tree roots has to point to the most up to date
2020          * root for every subvolume and other tree.  So, we have to keep
2021          * the tree logging code from jumping in and changing any
2022          * of the trees.
2023          *
2024          * At this point in the commit, there can't be any tree-log
2025          * writers, but a little lower down we drop the trans mutex
2026          * and let new people in.  By holding the tree_log_mutex
2027          * from now until after the super is written, we avoid races
2028          * with the tree-log code.
2029          */
2030         mutex_lock(&root->fs_info->tree_log_mutex);
2031
2032         ret = commit_fs_roots(trans, root);
2033         if (ret) {
2034                 mutex_unlock(&root->fs_info->tree_log_mutex);
2035                 mutex_unlock(&root->fs_info->reloc_mutex);
2036                 goto scrub_continue;
2037         }
2038
2039         /*
2040          * Since the transaction is done, we can apply the pending changes
2041          * before the next transaction.
2042          */
2043         btrfs_apply_pending_changes(root->fs_info);
2044
2045         /* commit_fs_roots gets rid of all the tree log roots, it is now
2046          * safe to free the root of tree log roots
2047          */
2048         btrfs_free_log_root_tree(trans, root->fs_info);
2049
2050         /*
2051          * Since fs roots are all committed, we can get a quite accurate
2052          * new_roots. So let's do quota accounting.
2053          */
2054         ret = btrfs_qgroup_account_extents(trans, root->fs_info);
2055         if (ret < 0) {
2056                 mutex_unlock(&root->fs_info->tree_log_mutex);
2057                 mutex_unlock(&root->fs_info->reloc_mutex);
2058                 goto scrub_continue;
2059         }
2060
2061         ret = commit_cowonly_roots(trans, root);
2062         if (ret) {
2063                 mutex_unlock(&root->fs_info->tree_log_mutex);
2064                 mutex_unlock(&root->fs_info->reloc_mutex);
2065                 goto scrub_continue;
2066         }
2067
2068         /*
2069          * The tasks which save the space cache and inode cache may also
2070          * update ->aborted, check it.
2071          */
2072         if (unlikely(ACCESS_ONCE(cur_trans->aborted))) {
2073                 ret = cur_trans->aborted;
2074                 mutex_unlock(&root->fs_info->tree_log_mutex);
2075                 mutex_unlock(&root->fs_info->reloc_mutex);
2076                 goto scrub_continue;
2077         }
2078
2079         btrfs_prepare_extent_commit(trans, root);
2080
2081         cur_trans = root->fs_info->running_transaction;
2082
2083         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
2084                             root->fs_info->tree_root->node);
2085         list_add_tail(&root->fs_info->tree_root->dirty_list,
2086                       &cur_trans->switch_commits);
2087
2088         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
2089                             root->fs_info->chunk_root->node);
2090         list_add_tail(&root->fs_info->chunk_root->dirty_list,
2091                       &cur_trans->switch_commits);
2092
2093         switch_commit_roots(cur_trans, root->fs_info);
2094
2095         assert_qgroups_uptodate(trans);
2096         ASSERT(list_empty(&cur_trans->dirty_bgs));
2097         ASSERT(list_empty(&cur_trans->io_bgs));
2098         update_super_roots(root);
2099
2100         btrfs_set_super_log_root(root->fs_info->super_copy, 0);
2101         btrfs_set_super_log_root_level(root->fs_info->super_copy, 0);
2102         memcpy(root->fs_info->super_for_commit, root->fs_info->super_copy,
2103                sizeof(*root->fs_info->super_copy));
2104
2105         btrfs_update_commit_device_size(root->fs_info);
2106         btrfs_update_commit_device_bytes_used(root, cur_trans);
2107
2108         clear_bit(BTRFS_INODE_BTREE_LOG1_ERR, &btree_ino->runtime_flags);
2109         clear_bit(BTRFS_INODE_BTREE_LOG2_ERR, &btree_ino->runtime_flags);
2110
2111         btrfs_trans_release_chunk_metadata(trans);
2112
2113         spin_lock(&root->fs_info->trans_lock);
2114         cur_trans->state = TRANS_STATE_UNBLOCKED;
2115         root->fs_info->running_transaction = NULL;
2116         spin_unlock(&root->fs_info->trans_lock);
2117         mutex_unlock(&root->fs_info->reloc_mutex);
2118
2119         wake_up(&root->fs_info->transaction_wait);
2120
2121         ret = btrfs_write_and_wait_transaction(trans, root);
2122         if (ret) {
2123                 btrfs_std_error(root->fs_info, ret,
2124                             "Error while writing out transaction");
2125                 mutex_unlock(&root->fs_info->tree_log_mutex);
2126                 goto scrub_continue;
2127         }
2128
2129         ret = write_ctree_super(trans, root, 0);
2130         if (ret) {
2131                 mutex_unlock(&root->fs_info->tree_log_mutex);
2132                 goto scrub_continue;
2133         }
2134
2135         /*
2136          * the super is written, we can safely allow the tree-loggers
2137          * to go about their business
2138          */
2139         mutex_unlock(&root->fs_info->tree_log_mutex);
2140
2141         btrfs_finish_extent_commit(trans, root);
2142
2143         if (test_bit(BTRFS_TRANS_HAVE_FREE_BGS, &cur_trans->flags))
2144                 btrfs_clear_space_info_full(root->fs_info);
2145
2146         root->fs_info->last_trans_committed = cur_trans->transid;
2147         /*
2148          * We needn't acquire the lock here because there is no other task
2149          * which can change it.
2150          */
2151         cur_trans->state = TRANS_STATE_COMPLETED;
2152         wake_up(&cur_trans->commit_wait);
2153
2154         spin_lock(&root->fs_info->trans_lock);
2155         list_del_init(&cur_trans->list);
2156         spin_unlock(&root->fs_info->trans_lock);
2157
2158         btrfs_put_transaction(cur_trans);
2159         btrfs_put_transaction(cur_trans);
2160
2161         if (trans->type & __TRANS_FREEZABLE)
2162                 sb_end_intwrite(root->fs_info->sb);
2163
2164         trace_btrfs_transaction_commit(root);
2165
2166         btrfs_scrub_continue(root);
2167
2168         if (current->journal_info == trans)
2169                 current->journal_info = NULL;
2170
2171         kmem_cache_free(btrfs_trans_handle_cachep, trans);
2172
2173         if (current != root->fs_info->transaction_kthread &&
2174             current != root->fs_info->cleaner_kthread)
2175                 btrfs_run_delayed_iputs(root);
2176
2177         return ret;
2178
2179 scrub_continue:
2180         btrfs_scrub_continue(root);
2181 cleanup_transaction:
2182         btrfs_trans_release_metadata(trans, root);
2183         btrfs_trans_release_chunk_metadata(trans);
2184         trans->block_rsv = NULL;
2185         btrfs_warn(root->fs_info, "Skipping commit of aborted transaction.");
2186         if (current->journal_info == trans)
2187                 current->journal_info = NULL;
2188         cleanup_transaction(trans, root, ret);
2189
2190         return ret;
2191 }
2192
2193 /*
2194  * return < 0 if error
2195  * 0 if there are no more dead_roots at the time of call
2196  * 1 there are more to be processed, call me again
2197  *
2198  * The return value indicates there are certainly more snapshots to delete, but
2199  * if there comes a new one during processing, it may return 0. We don't mind,
2200  * because btrfs_commit_super will poke cleaner thread and it will process it a
2201  * few seconds later.
2202  */
2203 int btrfs_clean_one_deleted_snapshot(struct btrfs_root *root)
2204 {
2205         int ret;
2206         struct btrfs_fs_info *fs_info = root->fs_info;
2207
2208         spin_lock(&fs_info->trans_lock);
2209         if (list_empty(&fs_info->dead_roots)) {
2210                 spin_unlock(&fs_info->trans_lock);
2211                 return 0;
2212         }
2213         root = list_first_entry(&fs_info->dead_roots,
2214                         struct btrfs_root, root_list);
2215         list_del_init(&root->root_list);
2216         spin_unlock(&fs_info->trans_lock);
2217
2218         pr_debug("BTRFS: cleaner removing %llu\n", root->objectid);
2219
2220         btrfs_kill_all_delayed_nodes(root);
2221
2222         if (btrfs_header_backref_rev(root->node) <
2223                         BTRFS_MIXED_BACKREF_REV)
2224                 ret = btrfs_drop_snapshot(root, NULL, 0, 0);
2225         else
2226                 ret = btrfs_drop_snapshot(root, NULL, 1, 0);
2227
2228         return (ret < 0) ? 0 : 1;
2229 }
2230
2231 void btrfs_apply_pending_changes(struct btrfs_fs_info *fs_info)
2232 {
2233         unsigned long prev;
2234         unsigned long bit;
2235
2236         prev = xchg(&fs_info->pending_changes, 0);
2237         if (!prev)
2238                 return;
2239
2240         bit = 1 << BTRFS_PENDING_SET_INODE_MAP_CACHE;
2241         if (prev & bit)
2242                 btrfs_set_opt(fs_info->mount_opt, INODE_MAP_CACHE);
2243         prev &= ~bit;
2244
2245         bit = 1 << BTRFS_PENDING_CLEAR_INODE_MAP_CACHE;
2246         if (prev & bit)
2247                 btrfs_clear_opt(fs_info->mount_opt, INODE_MAP_CACHE);
2248         prev &= ~bit;
2249
2250         bit = 1 << BTRFS_PENDING_COMMIT;
2251         if (prev & bit)
2252                 btrfs_debug(fs_info, "pending commit done");
2253         prev &= ~bit;
2254
2255         if (prev)
2256                 btrfs_warn(fs_info,
2257                         "unknown pending changes left 0x%lx, ignoring", prev);
2258 }