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 "ctree.h"
  26 #include "disk-io.h"
  27 #include "transaction.h"
  28 #include "locking.h"
  29 #include "tree-log.h"
  30
  31 #define BTRFS_ROOT_TRANS_TAG 0
  32
  33 static noinline void put_transaction(struct btrfs_transaction *transaction)
  34 {
  35         WARN_ON(transaction->use_count == 0);
  36         transaction->use_count--;
  37         if (transaction->use_count == 0) {
  38                 list_del_init(&transaction->list);
  39                 memset(transaction, 0, sizeof(*transaction));
  40                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  41         }
  42 }
  43
  44 static noinline void switch_commit_root(struct btrfs_root *root)
  45 {
  46         free_extent_buffer(root->commit_root);
  47         root->commit_root = btrfs_root_node(root);
  48 }
  49
  50 /*
  51  * either allocate a new transaction or hop into the existing one
  52  */
  53 static noinline int join_transaction(struct btrfs_root *root)
  54 {
  55         struct btrfs_transaction *cur_trans;
  56         cur_trans = root->fs_info->running_transaction;
  57         if (!cur_trans) {
  58                 cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
  59                                              GFP_NOFS);
  60                 BUG_ON(!cur_trans);
  61                 root->fs_info->generation++;
  62                 cur_trans->num_writers = 1;
  63                 cur_trans->num_joined = 0;
  64                 cur_trans->transid = root->fs_info->generation;
  65                 init_waitqueue_head(&cur_trans->writer_wait);
  66                 init_waitqueue_head(&cur_trans->commit_wait);
  67                 cur_trans->in_commit = 0;
  68                 cur_trans->blocked = 0;
  69                 cur_trans->use_count = 1;
  70                 cur_trans->commit_done = 0;
  71                 cur_trans->start_time = get_seconds();
  72
  73                 cur_trans->delayed_refs.root = RB_ROOT;
  74                 cur_trans->delayed_refs.num_entries = 0;
  75                 cur_trans->delayed_refs.num_heads_ready = 0;
  76                 cur_trans->delayed_refs.num_heads = 0;
  77                 cur_trans->delayed_refs.flushing = 0;
  78                 cur_trans->delayed_refs.run_delayed_start = 0;
  79                 spin_lock_init(&cur_trans->delayed_refs.lock);
  80
  81                 INIT_LIST_HEAD(&cur_trans->pending_snapshots);
  82                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
  83                 extent_io_tree_init(&cur_trans->dirty_pages,
  84                                      root->fs_info->btree_inode->i_mapping,
  85                                      GFP_NOFS);
  86                 spin_lock(&root->fs_info->new_trans_lock);
  87                 root->fs_info->running_transaction = cur_trans;
  88                 spin_unlock(&root->fs_info->new_trans_lock);
  89         } else {
  90                 cur_trans->num_writers++;
  91                 cur_trans->num_joined++;
  92         }
  93
  94         return 0;
  95 }
  96
  97 /*
  98  * this does all the record keeping required to make sure that a reference
  99  * counted root is properly recorded in a given transaction.  This is required
 100  * to make sure the old root from before we joined the transaction is deleted
 101  * when the transaction commits
 102  */
 103 static noinline int record_root_in_trans(struct btrfs_trans_handle *trans,
 104                                          struct btrfs_root *root)
 105 {
 106         if (root->ref_cows && root->last_trans < trans->transid) {
 107                 WARN_ON(root == root->fs_info->extent_root);
 108                 WARN_ON(root->commit_root != root->node);
 109
 110                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 111                            (unsigned long)root->root_key.objectid,
 112                            BTRFS_ROOT_TRANS_TAG);
 113                 root->last_trans = trans->transid;
 114                 btrfs_init_reloc_root(trans, root);
 115         }
 116         return 0;
 117 }
 118
 119 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 120                                struct btrfs_root *root)
 121 {
 122         if (!root->ref_cows)
 123                 return 0;
 124
 125         mutex_lock(&root->fs_info->trans_mutex);
 126         if (root->last_trans == trans->transid) {
 127                 mutex_unlock(&root->fs_info->trans_mutex);
 128                 return 0;
 129         }
 130
 131         record_root_in_trans(trans, root);
 132         mutex_unlock(&root->fs_info->trans_mutex);
 133         return 0;
 134 }
 135
 136 /* wait for commit against the current transaction to become unblocked
 137  * when this is done, it is safe to start a new transaction, but the current
 138  * transaction might not be fully on disk.
 139  */
 140 static void wait_current_trans(struct btrfs_root *root)
 141 {
 142         struct btrfs_transaction *cur_trans;
 143
 144         cur_trans = root->fs_info->running_transaction;
 145         if (cur_trans && cur_trans->blocked) {
 146                 DEFINE_WAIT(wait);
 147                 cur_trans->use_count++;
 148                 while (1) {
 149                         prepare_to_wait(&root->fs_info->transaction_wait, &wait,
 150                                         TASK_UNINTERRUPTIBLE);
 151                         if (!cur_trans->blocked)
 152                                 break;
 153                         mutex_unlock(&root->fs_info->trans_mutex);
 154                         schedule();
 155                         mutex_lock(&root->fs_info->trans_mutex);
 156                 }
 157                 finish_wait(&root->fs_info->transaction_wait, &wait);
 158                 put_transaction(cur_trans);
 159         }
 160 }
 161
 162 enum btrfs_trans_type {
 163         TRANS_START,
 164         TRANS_JOIN,
 165         TRANS_USERSPACE,
 166         TRANS_JOIN_NOLOCK,
 167 };
 168
 169 static int may_wait_transaction(struct btrfs_root *root, int type)
 170 {
 171         if (!root->fs_info->log_root_recovering &&
 172             ((type == TRANS_START && !root->fs_info->open_ioctl_trans) ||
 173              type == TRANS_USERSPACE))
 174                 return 1;
 175         return 0;
 176 }
 177
 178 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 179                                                     u64 num_items, int type)
 180 {
 181         struct btrfs_trans_handle *h;
 182         struct btrfs_transaction *cur_trans;
 183         int ret;
 184
 185         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
 186                 return ERR_PTR(-EROFS);
 187 again:
 188         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 189         if (!h)
 190                 return ERR_PTR(-ENOMEM);
 191
 192         if (type != TRANS_JOIN_NOLOCK)
 193                 mutex_lock(&root->fs_info->trans_mutex);
 194         if (may_wait_transaction(root, type))
 195                 wait_current_trans(root);
 196
 197         ret = join_transaction(root);
 198         BUG_ON(ret);
 199
 200         cur_trans = root->fs_info->running_transaction;
 201         cur_trans->use_count++;
 202         if (type != TRANS_JOIN_NOLOCK)
 203                 mutex_unlock(&root->fs_info->trans_mutex);
 204
 205         h->transid = cur_trans->transid;
 206         h->transaction = cur_trans;
 207         h->blocks_used = 0;
 208         h->block_group = 0;
 209         h->bytes_reserved = 0;
 210         h->delayed_ref_updates = 0;
 211         h->block_rsv = NULL;
 212
 213         smp_mb();
 214         if (cur_trans->blocked && may_wait_transaction(root, type)) {
 215                 btrfs_commit_transaction(h, root);
 216                 goto again;
 217         }
 218
 219         if (num_items > 0) {
 220                 ret = btrfs_trans_reserve_metadata(h, root, num_items);
 221                 if (ret == -EAGAIN) {
 222                         btrfs_commit_transaction(h, root);
 223                         goto again;
 224                 }
 225                 if (ret < 0) {
 226                         btrfs_end_transaction(h, root);
 227                         return ERR_PTR(ret);
 228                 }
 229         }
 230
 231         if (type != TRANS_JOIN_NOLOCK)
 232                 mutex_lock(&root->fs_info->trans_mutex);
 233         record_root_in_trans(h, root);
 234         if (type != TRANS_JOIN_NOLOCK)
 235                 mutex_unlock(&root->fs_info->trans_mutex);
 236
 237         if (!current->journal_info && type != TRANS_USERSPACE)
 238                 current->journal_info = h;
 239         return h;
 240 }
 241
 242 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 243                                                    int num_items)
 244 {
 245         return start_transaction(root, num_items, TRANS_START);
 246 }
 247 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
 248                                                    int num_blocks)
 249 {
 250         return start_transaction(root, 0, TRANS_JOIN);
 251 }
 252
 253 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root,
 254                                                           int num_blocks)
 255 {
 256         return start_transaction(root, 0, TRANS_JOIN_NOLOCK);
 257 }
 258
 259 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
 260                                                          int num_blocks)
 261 {
 262         return start_transaction(r, 0, TRANS_USERSPACE);
 263 }
 264
 265 /* wait for a transaction commit to be fully complete */
 266 static noinline int wait_for_commit(struct btrfs_root *root,
 267                                     struct btrfs_transaction *commit)
 268 {
 269         DEFINE_WAIT(wait);
 270         mutex_lock(&root->fs_info->trans_mutex);
 271         while (!commit->commit_done) {
 272                 prepare_to_wait(&commit->commit_wait, &wait,
 273                                 TASK_UNINTERRUPTIBLE);
 274                 if (commit->commit_done)
 275                         break;
 276                 mutex_unlock(&root->fs_info->trans_mutex);
 277                 schedule();
 278                 mutex_lock(&root->fs_info->trans_mutex);
 279         }
 280         mutex_unlock(&root->fs_info->trans_mutex);
 281         finish_wait(&commit->commit_wait, &wait);
 282         return 0;
 283 }
 284
 285 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 286 {
 287         struct btrfs_transaction *cur_trans = NULL, *t;
 288         int ret;
 289
 290         mutex_lock(&root->fs_info->trans_mutex);
 291
 292         ret = 0;
 293         if (transid) {
 294                 if (transid <= root->fs_info->last_trans_committed)
 295                         goto out_unlock;
 296
 297                 /* find specified transaction */
 298                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 299                         if (t->transid == transid) {
 300                                 cur_trans = t;
 301                                 break;
 302                         }
 303                         if (t->transid > transid)
 304                                 break;
 305                 }
 306                 ret = -EINVAL;
 307                 if (!cur_trans)
 308                         goto out_unlock;  /* bad transid */
 309         } else {
 310                 /* find newest transaction that is committing | committed */
 311                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 312                                             list) {
 313                         if (t->in_commit) {
 314                                 if (t->commit_done)
 315                                         goto out_unlock;
 316                                 cur_trans = t;
 317                                 break;
 318                         }
 319                 }
 320                 if (!cur_trans)
 321                         goto out_unlock;  /* nothing committing|committed */
 322         }
 323
 324         cur_trans->use_count++;
 325         mutex_unlock(&root->fs_info->trans_mutex);
 326
 327         wait_for_commit(root, cur_trans);
 328
 329         mutex_lock(&root->fs_info->trans_mutex);
 330         put_transaction(cur_trans);
 331         ret = 0;
 332 out_unlock:
 333         mutex_unlock(&root->fs_info->trans_mutex);
 334         return ret;
 335 }
 336
 337 #if 0
 338 /*
 339  * rate limit against the drop_snapshot code.  This helps to slow down new
 340  * operations if the drop_snapshot code isn't able to keep up.
 341  */
 342 static void throttle_on_drops(struct btrfs_root *root)
 343 {
 344         struct btrfs_fs_info *info = root->fs_info;
 345         int harder_count = 0;
 346
 347 harder:
 348         if (atomic_read(&info->throttles)) {
 349                 DEFINE_WAIT(wait);
 350                 int thr;
 351                 thr = atomic_read(&info->throttle_gen);
 352
 353                 do {
 354                         prepare_to_wait(&info->transaction_throttle,
 355                                         &wait, TASK_UNINTERRUPTIBLE);
 356                         if (!atomic_read(&info->throttles)) {
 357                                 finish_wait(&info->transaction_throttle, &wait);
 358                                 break;
 359                         }
 360                         schedule();
 361                         finish_wait(&info->transaction_throttle, &wait);
 362                 } while (thr == atomic_read(&info->throttle_gen));
 363                 harder_count++;
 364
 365                 if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
 366                     harder_count < 2)
 367                         goto harder;
 368
 369                 if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
 370                     harder_count < 10)
 371                         goto harder;
 372
 373                 if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
 374                     harder_count < 20)
 375                         goto harder;
 376         }
 377 }
 378 #endif
 379
 380 void btrfs_throttle(struct btrfs_root *root)
 381 {
 382         mutex_lock(&root->fs_info->trans_mutex);
 383         if (!root->fs_info->open_ioctl_trans)
 384                 wait_current_trans(root);
 385         mutex_unlock(&root->fs_info->trans_mutex);
 386 }
 387
 388 static int should_end_transaction(struct btrfs_trans_handle *trans,
 389                                   struct btrfs_root *root)
 390 {
 391         int ret;
 392         ret = btrfs_block_rsv_check(trans, root,
 393                                     &root->fs_info->global_block_rsv, 0, 5);
 394         return ret ? 1 : 0;
 395 }
 396
 397 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 398                                  struct btrfs_root *root)
 399 {
 400         struct btrfs_transaction *cur_trans = trans->transaction;
 401         int updates;
 402
 403         if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
 404                 return 1;
 405
 406         updates = trans->delayed_ref_updates;
 407         trans->delayed_ref_updates = 0;
 408         if (updates)
 409                 btrfs_run_delayed_refs(trans, root, updates);
 410
 411         return should_end_transaction(trans, root);
 412 }
 413
 414 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 415                           struct btrfs_root *root, int throttle, int lock)
 416 {
 417         struct btrfs_transaction *cur_trans = trans->transaction;
 418         struct btrfs_fs_info *info = root->fs_info;
 419         int count = 0;
 420
 421         while (count < 4) {
 422                 unsigned long cur = trans->delayed_ref_updates;
 423                 trans->delayed_ref_updates = 0;
 424                 if (cur &&
 425                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 426                         trans->delayed_ref_updates = 0;
 427
 428                         /*
 429                          * do a full flush if the transaction is trying
 430                          * to close
 431                          */
 432                         if (trans->transaction->delayed_refs.flushing)
 433                                 cur = 0;
 434                         btrfs_run_delayed_refs(trans, root, cur);
 435                 } else {
 436                         break;
 437                 }
 438                 count++;
 439         }
 440
 441         btrfs_trans_release_metadata(trans, root);
 442
 443         if (lock && !root->fs_info->open_ioctl_trans &&
 444             should_end_transaction(trans, root))
 445                 trans->transaction->blocked = 1;
 446
 447         if (lock && cur_trans->blocked && !cur_trans->in_commit) {
 448                 if (throttle)
 449                         return btrfs_commit_transaction(trans, root);
 450                 else
 451                         wake_up_process(info->transaction_kthread);
 452         }
 453
 454         if (lock)
 455                 mutex_lock(&info->trans_mutex);
 456         WARN_ON(cur_trans != info->running_transaction);
 457         WARN_ON(cur_trans->num_writers < 1);
 458         cur_trans->num_writers--;
 459
 460         smp_mb();
 461         if (waitqueue_active(&cur_trans->writer_wait))
 462                 wake_up(&cur_trans->writer_wait);
 463         put_transaction(cur_trans);
 464         if (lock)
 465                 mutex_unlock(&info->trans_mutex);
 466
 467         if (current->journal_info == trans)
 468                 current->journal_info = NULL;
 469         memset(trans, 0, sizeof(*trans));
 470         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 471
 472         if (throttle)
 473                 btrfs_run_delayed_iputs(root);
 474
 475         return 0;
 476 }
 477
 478 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 479                           struct btrfs_root *root)
 480 {
 481         return __btrfs_end_transaction(trans, root, 0, 1);
 482 }
 483
 484 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 485                                    struct btrfs_root *root)
 486 {
 487         return __btrfs_end_transaction(trans, root, 1, 1);
 488 }
 489
 490 int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
 491                                  struct btrfs_root *root)
 492 {
 493         return __btrfs_end_transaction(trans, root, 0, 0);
 494 }
 495
 496 /*
 497  * when btree blocks are allocated, they have some corresponding bits set for
 498  * them in one of two extent_io trees.  This is used to make sure all of
 499  * those extents are sent to disk but does not wait on them
 500  */
 501 int btrfs_write_marked_extents(struct btrfs_root *root,
 502                                struct extent_io_tree *dirty_pages, int mark)
 503 {
 504         int ret;
 505         int err = 0;
 506         int werr = 0;
 507         struct page *page;
 508         struct inode *btree_inode = root->fs_info->btree_inode;
 509         u64 start = 0;
 510         u64 end;
 511         unsigned long index;
 512
 513         while (1) {
 514                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 515                                             mark);
 516                 if (ret)
 517                         break;
 518                 while (start <= end) {
 519                         cond_resched();
 520
 521                         index = start >> PAGE_CACHE_SHIFT;
 522                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 523                         page = find_get_page(btree_inode->i_mapping, index);
 524                         if (!page)
 525                                 continue;
 526
 527                         btree_lock_page_hook(page);
 528                         if (!page->mapping) {
 529                                 unlock_page(page);
 530                                 page_cache_release(page);
 531                                 continue;
 532                         }
 533
 534                         if (PageWriteback(page)) {
 535                                 if (PageDirty(page))
 536                                         wait_on_page_writeback(page);
 537                                 else {
 538                                         unlock_page(page);
 539                                         page_cache_release(page);
 540                                         continue;
 541                                 }
 542                         }
 543                         err = write_one_page(page, 0);
 544                         if (err)
 545                                 werr = err;
 546                         page_cache_release(page);
 547                 }
 548         }
 549         if (err)
 550                 werr = err;
 551         return werr;
 552 }
 553
 554 /*
 555  * when btree blocks are allocated, they have some corresponding bits set for
 556  * them in one of two extent_io trees.  This is used to make sure all of
 557  * those extents are on disk for transaction or log commit.  We wait
 558  * on all the pages and clear them from the dirty pages state tree
 559  */
 560 int btrfs_wait_marked_extents(struct btrfs_root *root,
 561                               struct extent_io_tree *dirty_pages, int mark)
 562 {
 563         int ret;
 564         int err = 0;
 565         int werr = 0;
 566         struct page *page;
 567         struct inode *btree_inode = root->fs_info->btree_inode;
 568         u64 start = 0;
 569         u64 end;
 570         unsigned long index;
 571
 572         while (1) {
 573                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 574                                             mark);
 575                 if (ret)
 576                         break;
 577
 578                 clear_extent_bits(dirty_pages, start, end, mark, GFP_NOFS);
 579                 while (start <= end) {
 580                         index = start >> PAGE_CACHE_SHIFT;
 581                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 582                         page = find_get_page(btree_inode->i_mapping, index);
 583                         if (!page)
 584                                 continue;
 585                         if (PageDirty(page)) {
 586                                 btree_lock_page_hook(page);
 587                                 wait_on_page_writeback(page);
 588                                 err = write_one_page(page, 0);
 589                                 if (err)
 590                                         werr = err;
 591                         }
 592                         wait_on_page_writeback(page);
 593                         page_cache_release(page);
 594                         cond_resched();
 595                 }
 596         }
 597         if (err)
 598                 werr = err;
 599         return werr;
 600 }
 601
 602 /*
 603  * when btree blocks are allocated, they have some corresponding bits set for
 604  * them in one of two extent_io trees.  This is used to make sure all of
 605  * those extents are on disk for transaction or log commit
 606  */
 607 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 608                                 struct extent_io_tree *dirty_pages, int mark)
 609 {
 610         int ret;
 611         int ret2;
 612
 613         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 614         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 615         return ret || ret2;
 616 }
 617
 618 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 619                                      struct btrfs_root *root)
 620 {
 621         if (!trans || !trans->transaction) {
 622                 struct inode *btree_inode;
 623                 btree_inode = root->fs_info->btree_inode;
 624                 return filemap_write_and_wait(btree_inode->i_mapping);
 625         }
 626         return btrfs_write_and_wait_marked_extents(root,
 627                                            &trans->transaction->dirty_pages,
 628                                            EXTENT_DIRTY);
 629 }
 630
 631 /*
 632  * this is used to update the root pointer in the tree of tree roots.
 633  *
 634  * But, in the case of the extent allocation tree, updating the root
 635  * pointer may allocate blocks which may change the root of the extent
 636  * allocation tree.
 637  *
 638  * So, this loops and repeats and makes sure the cowonly root didn't
 639  * change while the root pointer was being updated in the metadata.
 640  */
 641 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 642                                struct btrfs_root *root)
 643 {
 644         int ret;
 645         u64 old_root_bytenr;
 646         u64 old_root_used;
 647         struct btrfs_root *tree_root = root->fs_info->tree_root;
 648
 649         old_root_used = btrfs_root_used(&root->root_item);
 650         btrfs_write_dirty_block_groups(trans, root);
 651
 652         while (1) {
 653                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 654                 if (old_root_bytenr == root->node->start &&
 655                     old_root_used == btrfs_root_used(&root->root_item))
 656                         break;
 657
 658                 btrfs_set_root_node(&root->root_item, root->node);
 659                 ret = btrfs_update_root(trans, tree_root,
 660                                         &root->root_key,
 661                                         &root->root_item);
 662                 BUG_ON(ret);
 663
 664                 old_root_used = btrfs_root_used(&root->root_item);
 665                 ret = btrfs_write_dirty_block_groups(trans, root);
 666                 BUG_ON(ret);
 667         }
 668
 669         if (root != root->fs_info->extent_root)
 670                 switch_commit_root(root);
 671
 672         return 0;
 673 }
 674
 675 /*
 676  * update all the cowonly tree roots on disk
 677  */
 678 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 679                                          struct btrfs_root *root)
 680 {
 681         struct btrfs_fs_info *fs_info = root->fs_info;
 682         struct list_head *next;
 683         struct extent_buffer *eb;
 684         int ret;
 685
 686         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 687         BUG_ON(ret);
 688
 689         eb = btrfs_lock_root_node(fs_info->tree_root);
 690         btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
 691         btrfs_tree_unlock(eb);
 692         free_extent_buffer(eb);
 693
 694         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 695         BUG_ON(ret);
 696
 697         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 698                 next = fs_info->dirty_cowonly_roots.next;
 699                 list_del_init(next);
 700                 root = list_entry(next, struct btrfs_root, dirty_list);
 701
 702                 update_cowonly_root(trans, root);
 703         }
 704
 705         down_write(&fs_info->extent_commit_sem);
 706         switch_commit_root(fs_info->extent_root);
 707         up_write(&fs_info->extent_commit_sem);
 708
 709         return 0;
 710 }
 711
 712 /*
 713  * dead roots are old snapshots that need to be deleted.  This allocates
 714  * a dirty root struct and adds it into the list of dead roots that need to
 715  * be deleted
 716  */
 717 int btrfs_add_dead_root(struct btrfs_root *root)
 718 {
 719         mutex_lock(&root->fs_info->trans_mutex);
 720         list_add(&root->root_list, &root->fs_info->dead_roots);
 721         mutex_unlock(&root->fs_info->trans_mutex);
 722         return 0;
 723 }
 724
 725 /*
 726  * update all the cowonly tree roots on disk
 727  */
 728 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 729                                     struct btrfs_root *root)
 730 {
 731         struct btrfs_root *gang[8];
 732         struct btrfs_fs_info *fs_info = root->fs_info;
 733         int i;
 734         int ret;
 735         int err = 0;
 736
 737         while (1) {
 738                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
 739                                                  (void **)gang, 0,
 740                                                  ARRAY_SIZE(gang),
 741                                                  BTRFS_ROOT_TRANS_TAG);
 742                 if (ret == 0)
 743                         break;
 744                 for (i = 0; i < ret; i++) {
 745                         root = gang[i];
 746                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
 747                                         (unsigned long)root->root_key.objectid,
 748                                         BTRFS_ROOT_TRANS_TAG);
 749
 750                         btrfs_free_log(trans, root);
 751                         btrfs_update_reloc_root(trans, root);
 752                         btrfs_orphan_commit_root(trans, root);
 753
 754                         if (root->commit_root != root->node) {
 755                                 switch_commit_root(root);
 756                                 btrfs_set_root_node(&root->root_item,
 757                                                     root->node);
 758                         }
 759
 760                         err = btrfs_update_root(trans, fs_info->tree_root,
 761                                                 &root->root_key,
 762                                                 &root->root_item);
 763                         if (err)
 764                                 break;
 765                 }
 766         }
 767         return err;
 768 }
 769
 770 /*
 771  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
 772  * otherwise every leaf in the btree is read and defragged.
 773  */
 774 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 775 {
 776         struct btrfs_fs_info *info = root->fs_info;
 777         struct btrfs_trans_handle *trans;
 778         int ret;
 779         unsigned long nr;
 780
 781         if (xchg(&root->defrag_running, 1))
 782                 return 0;
 783
 784         while (1) {
 785                 trans = btrfs_start_transaction(root, 0);
 786                 if (IS_ERR(trans))
 787                         return PTR_ERR(trans);
 788
 789                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 790
 791                 nr = trans->blocks_used;
 792                 btrfs_end_transaction(trans, root);
 793                 btrfs_btree_balance_dirty(info->tree_root, nr);
 794                 cond_resched();
 795
 796                 if (root->fs_info->closing || ret != -EAGAIN)
 797                         break;
 798         }
 799         root->defrag_running = 0;
 800         return ret;
 801 }
 802
 803 #if 0
 804 /*
 805  * when dropping snapshots, we generate a ton of delayed refs, and it makes
 806  * sense not to join the transaction while it is trying to flush the current
 807  * queue of delayed refs out.
 808  *
 809  * This is used by the drop snapshot code only
 810  */
 811 static noinline int wait_transaction_pre_flush(struct btrfs_fs_info *info)
 812 {
 813         DEFINE_WAIT(wait);
 814
 815         mutex_lock(&info->trans_mutex);
 816         while (info->running_transaction &&
 817                info->running_transaction->delayed_refs.flushing) {
 818                 prepare_to_wait(&info->transaction_wait, &wait,
 819                                 TASK_UNINTERRUPTIBLE);
 820                 mutex_unlock(&info->trans_mutex);
 821
 822                 schedule();
 823
 824                 mutex_lock(&info->trans_mutex);
 825                 finish_wait(&info->transaction_wait, &wait);
 826         }
 827         mutex_unlock(&info->trans_mutex);
 828         return 0;
 829 }
 830
 831 /*
 832  * Given a list of roots that need to be deleted, call btrfs_drop_snapshot on
 833  * all of them
 834  */
 835 int btrfs_drop_dead_root(struct btrfs_root *root)
 836 {
 837         struct btrfs_trans_handle *trans;
 838         struct btrfs_root *tree_root = root->fs_info->tree_root;
 839         unsigned long nr;
 840         int ret;
 841
 842         while (1) {
 843                 /*
 844                  * we don't want to jump in and create a bunch of
 845                  * delayed refs if the transaction is starting to close
 846                  */
 847                 wait_transaction_pre_flush(tree_root->fs_info);
 848                 trans = btrfs_start_transaction(tree_root, 1);
 849
 850                 /*
 851                  * we've joined a transaction, make sure it isn't
 852                  * closing right now
 853                  */
 854                 if (trans->transaction->delayed_refs.flushing) {
 855                         btrfs_end_transaction(trans, tree_root);
 856                         continue;
 857                 }
 858
 859                 ret = btrfs_drop_snapshot(trans, root);
 860                 if (ret != -EAGAIN)
 861                         break;
 862
 863                 ret = btrfs_update_root(trans, tree_root,
 864                                         &root->root_key,
 865                                         &root->root_item);
 866                 if (ret)
 867                         break;
 868
 869                 nr = trans->blocks_used;
 870                 ret = btrfs_end_transaction(trans, tree_root);
 871                 BUG_ON(ret);
 872
 873                 btrfs_btree_balance_dirty(tree_root, nr);
 874                 cond_resched();
 875         }
 876         BUG_ON(ret);
 877
 878         ret = btrfs_del_root(trans, tree_root, &root->root_key);
 879         BUG_ON(ret);
 880
 881         nr = trans->blocks_used;
 882         ret = btrfs_end_transaction(trans, tree_root);
 883         BUG_ON(ret);
 884
 885         free_extent_buffer(root->node);
 886         free_extent_buffer(root->commit_root);
 887         kfree(root);
 888
 889         btrfs_btree_balance_dirty(tree_root, nr);
 890         return ret;
 891 }
 892 #endif
 893
 894 /*
 895  * new snapshots need to be created at a very specific time in the
 896  * transaction commit.  This does the actual creation
 897  */
 898 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 899                                    struct btrfs_fs_info *fs_info,
 900                                    struct btrfs_pending_snapshot *pending)
 901 {
 902         struct btrfs_key key;
 903         struct btrfs_root_item *new_root_item;
 904         struct btrfs_root *tree_root = fs_info->tree_root;
 905         struct btrfs_root *root = pending->root;
 906         struct btrfs_root *parent_root;
 907         struct inode *parent_inode;
 908         struct dentry *parent;
 909         struct dentry *dentry;
 910         struct extent_buffer *tmp;
 911         struct extent_buffer *old;
 912         int ret;
 913         u64 to_reserve = 0;
 914         u64 index = 0;
 915         u64 objectid;
 916         u64 root_flags;
 917
 918         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 919         if (!new_root_item) {
 920                 pending->error = -ENOMEM;
 921                 goto fail;
 922         }
 923
 924         ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
 925         if (ret) {
 926                 pending->error = ret;
 927                 goto fail;
 928         }
 929
 930         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
 931         btrfs_orphan_pre_snapshot(trans, pending, &to_reserve);
 932
 933         if (to_reserve > 0) {
 934                 ret = btrfs_block_rsv_add(trans, root, &pending->block_rsv,
 935                                           to_reserve);
 936                 if (ret) {
 937                         pending->error = ret;
 938                         goto fail;
 939                 }
 940         }
 941
 942         key.objectid = objectid;
 943         key.offset = (u64)-1;
 944         key.type = BTRFS_ROOT_ITEM_KEY;
 945
 946         trans->block_rsv = &pending->block_rsv;
 947
 948         dentry = pending->dentry;
 949         parent = dget_parent(dentry);
 950         parent_inode = parent->d_inode;
 951         parent_root = BTRFS_I(parent_inode)->root;
 952         record_root_in_trans(trans, parent_root);
 953
 954         /*
 955          * insert the directory item
 956          */
 957         ret = btrfs_set_inode_index(parent_inode, &index);
 958         BUG_ON(ret);
 959         ret = btrfs_insert_dir_item(trans, parent_root,
 960                                 dentry->d_name.name, dentry->d_name.len,
 961                                 parent_inode->i_ino, &key,
 962                                 BTRFS_FT_DIR, index);
 963         BUG_ON(ret);
 964
 965         btrfs_i_size_write(parent_inode, parent_inode->i_size +
 966                                          dentry->d_name.len * 2);
 967         ret = btrfs_update_inode(trans, parent_root, parent_inode);
 968         BUG_ON(ret);
 969
 970         record_root_in_trans(trans, root);
 971         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
 972         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
 973
 974         root_flags = btrfs_root_flags(new_root_item);
 975         if (pending->readonly)
 976                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
 977         else
 978                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
 979         btrfs_set_root_flags(new_root_item, root_flags);
 980
 981         old = btrfs_lock_root_node(root);
 982         btrfs_cow_block(trans, root, old, NULL, 0, &old);
 983         btrfs_set_lock_blocking(old);
 984
 985         btrfs_copy_root(trans, root, old, &tmp, objectid);
 986         btrfs_tree_unlock(old);
 987         free_extent_buffer(old);
 988
 989         btrfs_set_root_node(new_root_item, tmp);
 990         /* record when the snapshot was created in key.offset */
 991         key.offset = trans->transid;
 992         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
 993         btrfs_tree_unlock(tmp);
 994         free_extent_buffer(tmp);
 995         BUG_ON(ret);
 996
 997         /*
 998          * insert root back/forward references
 999          */
1000         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1001                                  parent_root->root_key.objectid,
1002                                  parent_inode->i_ino, index,
1003                                  dentry->d_name.name, dentry->d_name.len);
1004         BUG_ON(ret);
1005         dput(parent);
1006
1007         key.offset = (u64)-1;
1008         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1009         BUG_ON(IS_ERR(pending->snap));
1010
1011         btrfs_reloc_post_snapshot(trans, pending);
1012         btrfs_orphan_post_snapshot(trans, pending);
1013 fail:
1014         kfree(new_root_item);
1015         btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
1016         return 0;
1017 }
1018
1019 /*
1020  * create all the snapshots we've scheduled for creation
1021  */
1022 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1023                                              struct btrfs_fs_info *fs_info)
1024 {
1025         struct btrfs_pending_snapshot *pending;
1026         struct list_head *head = &trans->transaction->pending_snapshots;
1027         int ret;
1028
1029         list_for_each_entry(pending, head, list) {
1030                 ret = create_pending_snapshot(trans, fs_info, pending);
1031                 BUG_ON(ret);
1032         }
1033         return 0;
1034 }
1035
1036 static void update_super_roots(struct btrfs_root *root)
1037 {
1038         struct btrfs_root_item *root_item;
1039         struct btrfs_super_block *super;
1040
1041         super = &root->fs_info->super_copy;
1042
1043         root_item = &root->fs_info->chunk_root->root_item;
1044         super->chunk_root = root_item->bytenr;
1045         super->chunk_root_generation = root_item->generation;
1046         super->chunk_root_level = root_item->level;
1047
1048         root_item = &root->fs_info->tree_root->root_item;
1049         super->root = root_item->bytenr;
1050         super->generation = root_item->generation;
1051         super->root_level = root_item->level;
1052         if (super->cache_generation != 0 || btrfs_test_opt(root, SPACE_CACHE))
1053                 super->cache_generation = root_item->generation;
1054 }
1055
1056 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1057 {
1058         int ret = 0;
1059         spin_lock(&info->new_trans_lock);
1060         if (info->running_transaction)
1061                 ret = info->running_transaction->in_commit;
1062         spin_unlock(&info->new_trans_lock);
1063         return ret;
1064 }
1065
1066 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1067 {
1068         int ret = 0;
1069         spin_lock(&info->new_trans_lock);
1070         if (info->running_transaction)
1071                 ret = info->running_transaction->blocked;
1072         spin_unlock(&info->new_trans_lock);
1073         return ret;
1074 }
1075
1076 /*
1077  * wait for the current transaction commit to start and block subsequent
1078  * transaction joins
1079  */
1080 static void wait_current_trans_commit_start(struct btrfs_root *root,
1081                                             struct btrfs_transaction *trans)
1082 {
1083         DEFINE_WAIT(wait);
1084
1085         if (trans->in_commit)
1086                 return;
1087
1088         while (1) {
1089                 prepare_to_wait(&root->fs_info->transaction_blocked_wait, &wait,
1090                                 TASK_UNINTERRUPTIBLE);
1091                 if (trans->in_commit) {
1092                         finish_wait(&root->fs_info->transaction_blocked_wait,
1093                                     &wait);
1094                         break;
1095                 }
1096                 mutex_unlock(&root->fs_info->trans_mutex);
1097                 schedule();
1098                 mutex_lock(&root->fs_info->trans_mutex);
1099                 finish_wait(&root->fs_info->transaction_blocked_wait, &wait);
1100         }
1101 }
1102
1103 /*
1104  * wait for the current transaction to start and then become unblocked.
1105  * caller holds ref.
1106  */
1107 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1108                                          struct btrfs_transaction *trans)
1109 {
1110         DEFINE_WAIT(wait);
1111
1112         if (trans->commit_done || (trans->in_commit && !trans->blocked))
1113                 return;
1114
1115         while (1) {
1116                 prepare_to_wait(&root->fs_info->transaction_wait, &wait,
1117                                 TASK_UNINTERRUPTIBLE);
1118                 if (trans->commit_done ||
1119                     (trans->in_commit && !trans->blocked)) {
1120                         finish_wait(&root->fs_info->transaction_wait,
1121                                     &wait);
1122                         break;
1123                 }
1124                 mutex_unlock(&root->fs_info->trans_mutex);
1125                 schedule();
1126                 mutex_lock(&root->fs_info->trans_mutex);
1127                 finish_wait(&root->fs_info->transaction_wait,
1128                             &wait);
1129         }
1130 }
1131
1132 /*
1133  * commit transactions asynchronously. once btrfs_commit_transaction_async
1134  * returns, any subsequent transaction will not be allowed to join.
1135  */
1136 struct btrfs_async_commit {
1137         struct btrfs_trans_handle *newtrans;
1138         struct btrfs_root *root;
1139         struct delayed_work work;
1140 };
1141
1142 static void do_async_commit(struct work_struct *work)
1143 {
1144         struct btrfs_async_commit *ac =
1145                 container_of(work, struct btrfs_async_commit, work.work);
1146
1147         btrfs_commit_transaction(ac->newtrans, ac->root);
1148         kfree(ac);
1149 }
1150
1151 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1152                                    struct btrfs_root *root,
1153                                    int wait_for_unblock)
1154 {
1155         struct btrfs_async_commit *ac;
1156         struct btrfs_transaction *cur_trans;
1157
1158         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1159         BUG_ON(!ac);
1160
1161         INIT_DELAYED_WORK(&ac->work, do_async_commit);
1162         ac->root = root;
1163         ac->newtrans = btrfs_join_transaction(root, 0);
1164         if (IS_ERR(ac->newtrans)) {
1165                 int err = PTR_ERR(ac->newtrans);
1166                 kfree(ac);
1167                 return err;
1168         }
1169
1170         /* take transaction reference */
1171         mutex_lock(&root->fs_info->trans_mutex);
1172         cur_trans = trans->transaction;
1173         cur_trans->use_count++;
1174         mutex_unlock(&root->fs_info->trans_mutex);
1175
1176         btrfs_end_transaction(trans, root);
1177         schedule_delayed_work(&ac->work, 0);
1178
1179         /* wait for transaction to start and unblock */
1180         mutex_lock(&root->fs_info->trans_mutex);
1181         if (wait_for_unblock)
1182                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1183         else
1184                 wait_current_trans_commit_start(root, cur_trans);
1185         put_transaction(cur_trans);
1186         mutex_unlock(&root->fs_info->trans_mutex);
1187
1188         return 0;
1189 }
1190
1191 /*
1192  * btrfs_transaction state sequence:
1193  *    in_commit = 0, blocked = 0  (initial)
1194  *    in_commit = 1, blocked = 1
1195  *    blocked = 0
1196  *    commit_done = 1
1197  */
1198 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1199                              struct btrfs_root *root)
1200 {
1201         unsigned long joined = 0;
1202         struct btrfs_transaction *cur_trans;
1203         struct btrfs_transaction *prev_trans = NULL;
1204         DEFINE_WAIT(wait);
1205         int ret;
1206         int should_grow = 0;
1207         unsigned long now = get_seconds();
1208         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1209
1210         btrfs_run_ordered_operations(root, 0);
1211
1212         /* make a pass through all the delayed refs we have so far
1213          * any runnings procs may add more while we are here
1214          */
1215         ret = btrfs_run_delayed_refs(trans, root, 0);
1216         BUG_ON(ret);
1217
1218         btrfs_trans_release_metadata(trans, root);
1219
1220         cur_trans = trans->transaction;
1221         /*
1222          * set the flushing flag so procs in this transaction have to
1223          * start sending their work down.
1224          */
1225         cur_trans->delayed_refs.flushing = 1;
1226
1227         ret = btrfs_run_delayed_refs(trans, root, 0);
1228         BUG_ON(ret);
1229
1230         mutex_lock(&root->fs_info->trans_mutex);
1231         if (cur_trans->in_commit) {
1232                 cur_trans->use_count++;
1233                 mutex_unlock(&root->fs_info->trans_mutex);
1234                 btrfs_end_transaction(trans, root);
1235
1236                 ret = wait_for_commit(root, cur_trans);
1237                 BUG_ON(ret);
1238
1239                 mutex_lock(&root->fs_info->trans_mutex);
1240                 put_transaction(cur_trans);
1241                 mutex_unlock(&root->fs_info->trans_mutex);
1242
1243                 return 0;
1244         }
1245
1246         trans->transaction->in_commit = 1;
1247         trans->transaction->blocked = 1;
1248         wake_up(&root->fs_info->transaction_blocked_wait);
1249
1250         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1251                 prev_trans = list_entry(cur_trans->list.prev,
1252                                         struct btrfs_transaction, list);
1253                 if (!prev_trans->commit_done) {
1254                         prev_trans->use_count++;
1255                         mutex_unlock(&root->fs_info->trans_mutex);
1256
1257                         wait_for_commit(root, prev_trans);
1258
1259                         mutex_lock(&root->fs_info->trans_mutex);
1260                         put_transaction(prev_trans);
1261                 }
1262         }
1263
1264         if (now < cur_trans->start_time || now - cur_trans->start_time < 1)
1265                 should_grow = 1;
1266
1267         do {
1268                 int snap_pending = 0;
1269                 joined = cur_trans->num_joined;
1270                 if (!list_empty(&trans->transaction->pending_snapshots))
1271                         snap_pending = 1;
1272
1273                 WARN_ON(cur_trans != trans->transaction);
1274                 mutex_unlock(&root->fs_info->trans_mutex);
1275
1276                 if (flush_on_commit || snap_pending) {
1277                         btrfs_start_delalloc_inodes(root, 1);
1278                         ret = btrfs_wait_ordered_extents(root, 0, 1);
1279                         BUG_ON(ret);
1280                 }
1281
1282                 /*
1283                  * rename don't use btrfs_join_transaction, so, once we
1284                  * set the transaction to blocked above, we aren't going
1285                  * to get any new ordered operations.  We can safely run
1286                  * it here and no for sure that nothing new will be added
1287                  * to the list
1288                  */
1289                 btrfs_run_ordered_operations(root, 1);
1290
1291                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1292                                 TASK_UNINTERRUPTIBLE);
1293
1294                 smp_mb();
1295                 if (cur_trans->num_writers > 1)
1296                         schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1297                 else if (should_grow)
1298                         schedule_timeout(1);
1299
1300                 mutex_lock(&root->fs_info->trans_mutex);
1301                 finish_wait(&cur_trans->writer_wait, &wait);
1302         } while (cur_trans->num_writers > 1 ||
1303                  (should_grow && cur_trans->num_joined != joined));
1304
1305         ret = create_pending_snapshots(trans, root->fs_info);
1306         BUG_ON(ret);
1307
1308         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1309         BUG_ON(ret);
1310
1311         WARN_ON(cur_trans != trans->transaction);
1312
1313         /* btrfs_commit_tree_roots is responsible for getting the
1314          * various roots consistent with each other.  Every pointer
1315          * in the tree of tree roots has to point to the most up to date
1316          * root for every subvolume and other tree.  So, we have to keep
1317          * the tree logging code from jumping in and changing any
1318          * of the trees.
1319          *
1320          * At this point in the commit, there can't be any tree-log
1321          * writers, but a little lower down we drop the trans mutex
1322          * and let new people in.  By holding the tree_log_mutex
1323          * from now until after the super is written, we avoid races
1324          * with the tree-log code.
1325          */
1326         mutex_lock(&root->fs_info->tree_log_mutex);
1327
1328         ret = commit_fs_roots(trans, root);
1329         BUG_ON(ret);
1330
1331         /* commit_fs_roots gets rid of all the tree log roots, it is now
1332          * safe to free the root of tree log roots
1333          */
1334         btrfs_free_log_root_tree(trans, root->fs_info);
1335
1336         ret = commit_cowonly_roots(trans, root);
1337         BUG_ON(ret);
1338
1339         btrfs_prepare_extent_commit(trans, root);
1340
1341         cur_trans = root->fs_info->running_transaction;
1342         spin_lock(&root->fs_info->new_trans_lock);
1343         root->fs_info->running_transaction = NULL;
1344         spin_unlock(&root->fs_info->new_trans_lock);
1345
1346         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1347                             root->fs_info->tree_root->node);
1348         switch_commit_root(root->fs_info->tree_root);
1349
1350         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1351                             root->fs_info->chunk_root->node);
1352         switch_commit_root(root->fs_info->chunk_root);
1353
1354         update_super_roots(root);
1355
1356         if (!root->fs_info->log_root_recovering) {
1357                 btrfs_set_super_log_root(&root->fs_info->super_copy, 0);
1358                 btrfs_set_super_log_root_level(&root->fs_info->super_copy, 0);
1359         }
1360
1361         memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
1362                sizeof(root->fs_info->super_copy));
1363
1364         trans->transaction->blocked = 0;
1365
1366         wake_up(&root->fs_info->transaction_wait);
1367
1368         mutex_unlock(&root->fs_info->trans_mutex);
1369         ret = btrfs_write_and_wait_transaction(trans, root);
1370         BUG_ON(ret);
1371         write_ctree_super(trans, root, 0);
1372
1373         /*
1374          * the super is written, we can safely allow the tree-loggers
1375          * to go about their business
1376          */
1377         mutex_unlock(&root->fs_info->tree_log_mutex);
1378
1379         btrfs_finish_extent_commit(trans, root);
1380
1381         mutex_lock(&root->fs_info->trans_mutex);
1382
1383         cur_trans->commit_done = 1;
1384
1385         root->fs_info->last_trans_committed = cur_trans->transid;
1386
1387         wake_up(&cur_trans->commit_wait);
1388
1389         put_transaction(cur_trans);
1390         put_transaction(cur_trans);
1391
1392         mutex_unlock(&root->fs_info->trans_mutex);
1393
1394         if (current->journal_info == trans)
1395                 current->journal_info = NULL;
1396
1397         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1398
1399         if (current != root->fs_info->transaction_kthread)
1400                 btrfs_run_delayed_iputs(root);
1401
1402         return ret;
1403 }
1404
1405 /*
1406  * interface function to delete all the snapshots we have scheduled for deletion
1407  */
1408 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1409 {
1410         LIST_HEAD(list);
1411         struct btrfs_fs_info *fs_info = root->fs_info;
1412
1413         mutex_lock(&fs_info->trans_mutex);
1414         list_splice_init(&fs_info->dead_roots, &list);
1415         mutex_unlock(&fs_info->trans_mutex);
1416
1417         while (!list_empty(&list)) {
1418                 root = list_entry(list.next, struct btrfs_root, root_list);
1419                 list_del(&root->root_list);
1420
1421                 if (btrfs_header_backref_rev(root->node) <
1422                     BTRFS_MIXED_BACKREF_REV)
1423                         btrfs_drop_snapshot(root, NULL, 0);
1424                 else
1425                         btrfs_drop_snapshot(root, NULL, 1);
1426         }
1427         return 0;
1428 }