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                 if (!cur_trans)
  61                         return -ENOMEM;
  62                 root->fs_info->generation++;
  63                 cur_trans->num_writers = 1;
  64                 cur_trans->num_joined = 0;
  65                 cur_trans->transid = root->fs_info->generation;
  66                 init_waitqueue_head(&cur_trans->writer_wait);
  67                 init_waitqueue_head(&cur_trans->commit_wait);
  68                 cur_trans->in_commit = 0;
  69                 cur_trans->blocked = 0;
  70                 cur_trans->use_count = 1;
  71                 cur_trans->commit_done = 0;
  72                 cur_trans->start_time = get_seconds();
  73
  74                 cur_trans->delayed_refs.root = RB_ROOT;
  75                 cur_trans->delayed_refs.num_entries = 0;
  76                 cur_trans->delayed_refs.num_heads_ready = 0;
  77                 cur_trans->delayed_refs.num_heads = 0;
  78                 cur_trans->delayed_refs.flushing = 0;
  79                 cur_trans->delayed_refs.run_delayed_start = 0;
  80                 spin_lock_init(&cur_trans->delayed_refs.lock);
  81
  82                 INIT_LIST_HEAD(&cur_trans->pending_snapshots);
  83                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
  84                 extent_io_tree_init(&cur_trans->dirty_pages,
  85                                      root->fs_info->btree_inode->i_mapping,
  86                                      GFP_NOFS);
  87                 spin_lock(&root->fs_info->new_trans_lock);
  88                 root->fs_info->running_transaction = cur_trans;
  89                 spin_unlock(&root->fs_info->new_trans_lock);
  90         } else {
  91                 cur_trans->num_writers++;
  92                 cur_trans->num_joined++;
  93         }
  94
  95         return 0;
  96 }
  97
  98 /*
  99  * this does all the record keeping required to make sure that a reference
 100  * counted root is properly recorded in a given transaction.  This is required
 101  * to make sure the old root from before we joined the transaction is deleted
 102  * when the transaction commits
 103  */
 104 static noinline int record_root_in_trans(struct btrfs_trans_handle *trans,
 105                                          struct btrfs_root *root)
 106 {
 107         if (root->ref_cows && root->last_trans < trans->transid) {
 108                 WARN_ON(root == root->fs_info->extent_root);
 109                 WARN_ON(root->commit_root != root->node);
 110
 111                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 112                            (unsigned long)root->root_key.objectid,
 113                            BTRFS_ROOT_TRANS_TAG);
 114                 root->last_trans = trans->transid;
 115                 btrfs_init_reloc_root(trans, root);
 116         }
 117         return 0;
 118 }
 119
 120 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 121                                struct btrfs_root *root)
 122 {
 123         if (!root->ref_cows)
 124                 return 0;
 125
 126         mutex_lock(&root->fs_info->trans_mutex);
 127         if (root->last_trans == trans->transid) {
 128                 mutex_unlock(&root->fs_info->trans_mutex);
 129                 return 0;
 130         }
 131
 132         record_root_in_trans(trans, root);
 133         mutex_unlock(&root->fs_info->trans_mutex);
 134         return 0;
 135 }
 136
 137 /* wait for commit against the current transaction to become unblocked
 138  * when this is done, it is safe to start a new transaction, but the current
 139  * transaction might not be fully on disk.
 140  */
 141 static void wait_current_trans(struct btrfs_root *root)
 142 {
 143         struct btrfs_transaction *cur_trans;
 144
 145         cur_trans = root->fs_info->running_transaction;
 146         if (cur_trans && cur_trans->blocked) {
 147                 DEFINE_WAIT(wait);
 148                 cur_trans->use_count++;
 149                 while (1) {
 150                         prepare_to_wait(&root->fs_info->transaction_wait, &wait,
 151                                         TASK_UNINTERRUPTIBLE);
 152                         if (!cur_trans->blocked)
 153                                 break;
 154                         mutex_unlock(&root->fs_info->trans_mutex);
 155                         schedule();
 156                         mutex_lock(&root->fs_info->trans_mutex);
 157                 }
 158                 finish_wait(&root->fs_info->transaction_wait, &wait);
 159                 put_transaction(cur_trans);
 160         }
 161 }
 162
 163 enum btrfs_trans_type {
 164         TRANS_START,
 165         TRANS_JOIN,
 166         TRANS_USERSPACE,
 167         TRANS_JOIN_NOLOCK,
 168 };
 169
 170 static int may_wait_transaction(struct btrfs_root *root, int type)
 171 {
 172         if (!root->fs_info->log_root_recovering &&
 173             ((type == TRANS_START && !root->fs_info->open_ioctl_trans) ||
 174              type == TRANS_USERSPACE))
 175                 return 1;
 176         return 0;
 177 }
 178
 179 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 180                                                     u64 num_items, int type)
 181 {
 182         struct btrfs_trans_handle *h;
 183         struct btrfs_transaction *cur_trans;
 184         int ret;
 185
 186         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
 187                 return ERR_PTR(-EROFS);
 188 again:
 189         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 190         if (!h)
 191                 return ERR_PTR(-ENOMEM);
 192
 193         if (type != TRANS_JOIN_NOLOCK)
 194                 mutex_lock(&root->fs_info->trans_mutex);
 195         if (may_wait_transaction(root, type))
 196                 wait_current_trans(root);
 197
 198         ret = join_transaction(root);
 199         if (ret < 0) {
 200                 if (type != TRANS_JOIN_NOLOCK)
 201                         mutex_unlock(&root->fs_info->trans_mutex);
 202                 return ERR_PTR(ret);
 203         }
 204
 205         cur_trans = root->fs_info->running_transaction;
 206         cur_trans->use_count++;
 207         if (type != TRANS_JOIN_NOLOCK)
 208                 mutex_unlock(&root->fs_info->trans_mutex);
 209
 210         h->transid = cur_trans->transid;
 211         h->transaction = cur_trans;
 212         h->blocks_used = 0;
 213         h->block_group = 0;
 214         h->bytes_reserved = 0;
 215         h->delayed_ref_updates = 0;
 216         h->block_rsv = NULL;
 217
 218         smp_mb();
 219         if (cur_trans->blocked && may_wait_transaction(root, type)) {
 220                 btrfs_commit_transaction(h, root);
 221                 goto again;
 222         }
 223
 224         if (num_items > 0) {
 225                 ret = btrfs_trans_reserve_metadata(h, root, num_items);
 226                 if (ret == -EAGAIN) {
 227                         btrfs_commit_transaction(h, root);
 228                         goto again;
 229                 }
 230                 if (ret < 0) {
 231                         btrfs_end_transaction(h, root);
 232                         return ERR_PTR(ret);
 233                 }
 234         }
 235
 236         if (type != TRANS_JOIN_NOLOCK)
 237                 mutex_lock(&root->fs_info->trans_mutex);
 238         record_root_in_trans(h, root);
 239         if (type != TRANS_JOIN_NOLOCK)
 240                 mutex_unlock(&root->fs_info->trans_mutex);
 241
 242         if (!current->journal_info && type != TRANS_USERSPACE)
 243                 current->journal_info = h;
 244         return h;
 245 }
 246
 247 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 248                                                    int num_items)
 249 {
 250         return start_transaction(root, num_items, TRANS_START);
 251 }
 252 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
 253                                                    int num_blocks)
 254 {
 255         return start_transaction(root, 0, TRANS_JOIN);
 256 }
 257
 258 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root,
 259                                                           int num_blocks)
 260 {
 261         return start_transaction(root, 0, TRANS_JOIN_NOLOCK);
 262 }
 263
 264 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
 265                                                          int num_blocks)
 266 {
 267         return start_transaction(r, 0, TRANS_USERSPACE);
 268 }
 269
 270 /* wait for a transaction commit to be fully complete */
 271 static noinline int wait_for_commit(struct btrfs_root *root,
 272                                     struct btrfs_transaction *commit)
 273 {
 274         DEFINE_WAIT(wait);
 275         mutex_lock(&root->fs_info->trans_mutex);
 276         while (!commit->commit_done) {
 277                 prepare_to_wait(&commit->commit_wait, &wait,
 278                                 TASK_UNINTERRUPTIBLE);
 279                 if (commit->commit_done)
 280                         break;
 281                 mutex_unlock(&root->fs_info->trans_mutex);
 282                 schedule();
 283                 mutex_lock(&root->fs_info->trans_mutex);
 284         }
 285         mutex_unlock(&root->fs_info->trans_mutex);
 286         finish_wait(&commit->commit_wait, &wait);
 287         return 0;
 288 }
 289
 290 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 291 {
 292         struct btrfs_transaction *cur_trans = NULL, *t;
 293         int ret;
 294
 295         mutex_lock(&root->fs_info->trans_mutex);
 296
 297         ret = 0;
 298         if (transid) {
 299                 if (transid <= root->fs_info->last_trans_committed)
 300                         goto out_unlock;
 301
 302                 /* find specified transaction */
 303                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 304                         if (t->transid == transid) {
 305                                 cur_trans = t;
 306                                 break;
 307                         }
 308                         if (t->transid > transid)
 309                                 break;
 310                 }
 311                 ret = -EINVAL;
 312                 if (!cur_trans)
 313                         goto out_unlock;  /* bad transid */
 314         } else {
 315                 /* find newest transaction that is committing | committed */
 316                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 317                                             list) {
 318                         if (t->in_commit) {
 319                                 if (t->commit_done)
 320                                         goto out_unlock;
 321                                 cur_trans = t;
 322                                 break;
 323                         }
 324                 }
 325                 if (!cur_trans)
 326                         goto out_unlock;  /* nothing committing|committed */
 327         }
 328
 329         cur_trans->use_count++;
 330         mutex_unlock(&root->fs_info->trans_mutex);
 331
 332         wait_for_commit(root, cur_trans);
 333
 334         mutex_lock(&root->fs_info->trans_mutex);
 335         put_transaction(cur_trans);
 336         ret = 0;
 337 out_unlock:
 338         mutex_unlock(&root->fs_info->trans_mutex);
 339         return ret;
 340 }
 341
 342 #if 0
 343 /*
 344  * rate limit against the drop_snapshot code.  This helps to slow down new
 345  * operations if the drop_snapshot code isn't able to keep up.
 346  */
 347 static void throttle_on_drops(struct btrfs_root *root)
 348 {
 349         struct btrfs_fs_info *info = root->fs_info;
 350         int harder_count = 0;
 351
 352 harder:
 353         if (atomic_read(&info->throttles)) {
 354                 DEFINE_WAIT(wait);
 355                 int thr;
 356                 thr = atomic_read(&info->throttle_gen);
 357
 358                 do {
 359                         prepare_to_wait(&info->transaction_throttle,
 360                                         &wait, TASK_UNINTERRUPTIBLE);
 361                         if (!atomic_read(&info->throttles)) {
 362                                 finish_wait(&info->transaction_throttle, &wait);
 363                                 break;
 364                         }
 365                         schedule();
 366                         finish_wait(&info->transaction_throttle, &wait);
 367                 } while (thr == atomic_read(&info->throttle_gen));
 368                 harder_count++;
 369
 370                 if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
 371                     harder_count < 2)
 372                         goto harder;
 373
 374                 if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
 375                     harder_count < 10)
 376                         goto harder;
 377
 378                 if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
 379                     harder_count < 20)
 380                         goto harder;
 381         }
 382 }
 383 #endif
 384
 385 void btrfs_throttle(struct btrfs_root *root)
 386 {
 387         mutex_lock(&root->fs_info->trans_mutex);
 388         if (!root->fs_info->open_ioctl_trans)
 389                 wait_current_trans(root);
 390         mutex_unlock(&root->fs_info->trans_mutex);
 391 }
 392
 393 static int should_end_transaction(struct btrfs_trans_handle *trans,
 394                                   struct btrfs_root *root)
 395 {
 396         int ret;
 397         ret = btrfs_block_rsv_check(trans, root,
 398                                     &root->fs_info->global_block_rsv, 0, 5);
 399         return ret ? 1 : 0;
 400 }
 401
 402 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 403                                  struct btrfs_root *root)
 404 {
 405         struct btrfs_transaction *cur_trans = trans->transaction;
 406         int updates;
 407
 408         if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
 409                 return 1;
 410
 411         updates = trans->delayed_ref_updates;
 412         trans->delayed_ref_updates = 0;
 413         if (updates)
 414                 btrfs_run_delayed_refs(trans, root, updates);
 415
 416         return should_end_transaction(trans, root);
 417 }
 418
 419 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 420                           struct btrfs_root *root, int throttle, int lock)
 421 {
 422         struct btrfs_transaction *cur_trans = trans->transaction;
 423         struct btrfs_fs_info *info = root->fs_info;
 424         int count = 0;
 425
 426         while (count < 4) {
 427                 unsigned long cur = trans->delayed_ref_updates;
 428                 trans->delayed_ref_updates = 0;
 429                 if (cur &&
 430                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 431                         trans->delayed_ref_updates = 0;
 432
 433                         /*
 434                          * do a full flush if the transaction is trying
 435                          * to close
 436                          */
 437                         if (trans->transaction->delayed_refs.flushing)
 438                                 cur = 0;
 439                         btrfs_run_delayed_refs(trans, root, cur);
 440                 } else {
 441                         break;
 442                 }
 443                 count++;
 444         }
 445
 446         btrfs_trans_release_metadata(trans, root);
 447
 448         if (lock && !root->fs_info->open_ioctl_trans &&
 449             should_end_transaction(trans, root))
 450                 trans->transaction->blocked = 1;
 451
 452         if (lock && cur_trans->blocked && !cur_trans->in_commit) {
 453                 if (throttle)
 454                         return btrfs_commit_transaction(trans, root);
 455                 else
 456                         wake_up_process(info->transaction_kthread);
 457         }
 458
 459         if (lock)
 460                 mutex_lock(&info->trans_mutex);
 461         WARN_ON(cur_trans != info->running_transaction);
 462         WARN_ON(cur_trans->num_writers < 1);
 463         cur_trans->num_writers--;
 464
 465         smp_mb();
 466         if (waitqueue_active(&cur_trans->writer_wait))
 467                 wake_up(&cur_trans->writer_wait);
 468         put_transaction(cur_trans);
 469         if (lock)
 470                 mutex_unlock(&info->trans_mutex);
 471
 472         if (current->journal_info == trans)
 473                 current->journal_info = NULL;
 474         memset(trans, 0, sizeof(*trans));
 475         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 476
 477         if (throttle)
 478                 btrfs_run_delayed_iputs(root);
 479
 480         return 0;
 481 }
 482
 483 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 484                           struct btrfs_root *root)
 485 {
 486         return __btrfs_end_transaction(trans, root, 0, 1);
 487 }
 488
 489 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 490                                    struct btrfs_root *root)
 491 {
 492         return __btrfs_end_transaction(trans, root, 1, 1);
 493 }
 494
 495 int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
 496                                  struct btrfs_root *root)
 497 {
 498         return __btrfs_end_transaction(trans, root, 0, 0);
 499 }
 500
 501 /*
 502  * when btree blocks are allocated, they have some corresponding bits set for
 503  * them in one of two extent_io trees.  This is used to make sure all of
 504  * those extents are sent to disk but does not wait on them
 505  */
 506 int btrfs_write_marked_extents(struct btrfs_root *root,
 507                                struct extent_io_tree *dirty_pages, int mark)
 508 {
 509         int ret;
 510         int err = 0;
 511         int werr = 0;
 512         struct page *page;
 513         struct inode *btree_inode = root->fs_info->btree_inode;
 514         u64 start = 0;
 515         u64 end;
 516         unsigned long index;
 517
 518         while (1) {
 519                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 520                                             mark);
 521                 if (ret)
 522                         break;
 523                 while (start <= end) {
 524                         cond_resched();
 525
 526                         index = start >> PAGE_CACHE_SHIFT;
 527                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 528                         page = find_get_page(btree_inode->i_mapping, index);
 529                         if (!page)
 530                                 continue;
 531
 532                         btree_lock_page_hook(page);
 533                         if (!page->mapping) {
 534                                 unlock_page(page);
 535                                 page_cache_release(page);
 536                                 continue;
 537                         }
 538
 539                         if (PageWriteback(page)) {
 540                                 if (PageDirty(page))
 541                                         wait_on_page_writeback(page);
 542                                 else {
 543                                         unlock_page(page);
 544                                         page_cache_release(page);
 545                                         continue;
 546                                 }
 547                         }
 548                         err = write_one_page(page, 0);
 549                         if (err)
 550                                 werr = err;
 551                         page_cache_release(page);
 552                 }
 553         }
 554         if (err)
 555                 werr = err;
 556         return werr;
 557 }
 558
 559 /*
 560  * when btree blocks are allocated, they have some corresponding bits set for
 561  * them in one of two extent_io trees.  This is used to make sure all of
 562  * those extents are on disk for transaction or log commit.  We wait
 563  * on all the pages and clear them from the dirty pages state tree
 564  */
 565 int btrfs_wait_marked_extents(struct btrfs_root *root,
 566                               struct extent_io_tree *dirty_pages, int mark)
 567 {
 568         int ret;
 569         int err = 0;
 570         int werr = 0;
 571         struct page *page;
 572         struct inode *btree_inode = root->fs_info->btree_inode;
 573         u64 start = 0;
 574         u64 end;
 575         unsigned long index;
 576
 577         while (1) {
 578                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 579                                             mark);
 580                 if (ret)
 581                         break;
 582
 583                 clear_extent_bits(dirty_pages, start, end, mark, GFP_NOFS);
 584                 while (start <= end) {
 585                         index = start >> PAGE_CACHE_SHIFT;
 586                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 587                         page = find_get_page(btree_inode->i_mapping, index);
 588                         if (!page)
 589                                 continue;
 590                         if (PageDirty(page)) {
 591                                 btree_lock_page_hook(page);
 592                                 wait_on_page_writeback(page);
 593                                 err = write_one_page(page, 0);
 594                                 if (err)
 595                                         werr = err;
 596                         }
 597                         wait_on_page_writeback(page);
 598                         page_cache_release(page);
 599                         cond_resched();
 600                 }
 601         }
 602         if (err)
 603                 werr = err;
 604         return werr;
 605 }
 606
 607 /*
 608  * when btree blocks are allocated, they have some corresponding bits set for
 609  * them in one of two extent_io trees.  This is used to make sure all of
 610  * those extents are on disk for transaction or log commit
 611  */
 612 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 613                                 struct extent_io_tree *dirty_pages, int mark)
 614 {
 615         int ret;
 616         int ret2;
 617
 618         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 619         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 620         return ret || ret2;
 621 }
 622
 623 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 624                                      struct btrfs_root *root)
 625 {
 626         if (!trans || !trans->transaction) {
 627                 struct inode *btree_inode;
 628                 btree_inode = root->fs_info->btree_inode;
 629                 return filemap_write_and_wait(btree_inode->i_mapping);
 630         }
 631         return btrfs_write_and_wait_marked_extents(root,
 632                                            &trans->transaction->dirty_pages,
 633                                            EXTENT_DIRTY);
 634 }
 635
 636 /*
 637  * this is used to update the root pointer in the tree of tree roots.
 638  *
 639  * But, in the case of the extent allocation tree, updating the root
 640  * pointer may allocate blocks which may change the root of the extent
 641  * allocation tree.
 642  *
 643  * So, this loops and repeats and makes sure the cowonly root didn't
 644  * change while the root pointer was being updated in the metadata.
 645  */
 646 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 647                                struct btrfs_root *root)
 648 {
 649         int ret;
 650         u64 old_root_bytenr;
 651         u64 old_root_used;
 652         struct btrfs_root *tree_root = root->fs_info->tree_root;
 653
 654         old_root_used = btrfs_root_used(&root->root_item);
 655         btrfs_write_dirty_block_groups(trans, root);
 656
 657         while (1) {
 658                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 659                 if (old_root_bytenr == root->node->start &&
 660                     old_root_used == btrfs_root_used(&root->root_item))
 661                         break;
 662
 663                 btrfs_set_root_node(&root->root_item, root->node);
 664                 ret = btrfs_update_root(trans, tree_root,
 665                                         &root->root_key,
 666                                         &root->root_item);
 667                 BUG_ON(ret);
 668
 669                 old_root_used = btrfs_root_used(&root->root_item);
 670                 ret = btrfs_write_dirty_block_groups(trans, root);
 671                 BUG_ON(ret);
 672         }
 673
 674         if (root != root->fs_info->extent_root)
 675                 switch_commit_root(root);
 676
 677         return 0;
 678 }
 679
 680 /*
 681  * update all the cowonly tree roots on disk
 682  */
 683 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 684                                          struct btrfs_root *root)
 685 {
 686         struct btrfs_fs_info *fs_info = root->fs_info;
 687         struct list_head *next;
 688         struct extent_buffer *eb;
 689         int ret;
 690
 691         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 692         BUG_ON(ret);
 693
 694         eb = btrfs_lock_root_node(fs_info->tree_root);
 695         btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
 696         btrfs_tree_unlock(eb);
 697         free_extent_buffer(eb);
 698
 699         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 700         BUG_ON(ret);
 701
 702         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 703                 next = fs_info->dirty_cowonly_roots.next;
 704                 list_del_init(next);
 705                 root = list_entry(next, struct btrfs_root, dirty_list);
 706
 707                 update_cowonly_root(trans, root);
 708         }
 709
 710         down_write(&fs_info->extent_commit_sem);
 711         switch_commit_root(fs_info->extent_root);
 712         up_write(&fs_info->extent_commit_sem);
 713
 714         return 0;
 715 }
 716
 717 /*
 718  * dead roots are old snapshots that need to be deleted.  This allocates
 719  * a dirty root struct and adds it into the list of dead roots that need to
 720  * be deleted
 721  */
 722 int btrfs_add_dead_root(struct btrfs_root *root)
 723 {
 724         mutex_lock(&root->fs_info->trans_mutex);
 725         list_add(&root->root_list, &root->fs_info->dead_roots);
 726         mutex_unlock(&root->fs_info->trans_mutex);
 727         return 0;
 728 }
 729
 730 /*
 731  * update all the cowonly tree roots on disk
 732  */
 733 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 734                                     struct btrfs_root *root)
 735 {
 736         struct btrfs_root *gang[8];
 737         struct btrfs_fs_info *fs_info = root->fs_info;
 738         int i;
 739         int ret;
 740         int err = 0;
 741
 742         while (1) {
 743                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
 744                                                  (void **)gang, 0,
 745                                                  ARRAY_SIZE(gang),
 746                                                  BTRFS_ROOT_TRANS_TAG);
 747                 if (ret == 0)
 748                         break;
 749                 for (i = 0; i < ret; i++) {
 750                         root = gang[i];
 751                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
 752                                         (unsigned long)root->root_key.objectid,
 753                                         BTRFS_ROOT_TRANS_TAG);
 754
 755                         btrfs_free_log(trans, root);
 756                         btrfs_update_reloc_root(trans, root);
 757                         btrfs_orphan_commit_root(trans, root);
 758
 759                         if (root->commit_root != root->node) {
 760                                 switch_commit_root(root);
 761                                 btrfs_set_root_node(&root->root_item,
 762                                                     root->node);
 763                         }
 764
 765                         err = btrfs_update_root(trans, fs_info->tree_root,
 766                                                 &root->root_key,
 767                                                 &root->root_item);
 768                         if (err)
 769                                 break;
 770                 }
 771         }
 772         return err;
 773 }
 774
 775 /*
 776  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
 777  * otherwise every leaf in the btree is read and defragged.
 778  */
 779 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 780 {
 781         struct btrfs_fs_info *info = root->fs_info;
 782         struct btrfs_trans_handle *trans;
 783         int ret;
 784         unsigned long nr;
 785
 786         if (xchg(&root->defrag_running, 1))
 787                 return 0;
 788
 789         while (1) {
 790                 trans = btrfs_start_transaction(root, 0);
 791                 if (IS_ERR(trans))
 792                         return PTR_ERR(trans);
 793
 794                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 795
 796                 nr = trans->blocks_used;
 797                 btrfs_end_transaction(trans, root);
 798                 btrfs_btree_balance_dirty(info->tree_root, nr);
 799                 cond_resched();
 800
 801                 if (root->fs_info->closing || ret != -EAGAIN)
 802                         break;
 803         }
 804         root->defrag_running = 0;
 805         return ret;
 806 }
 807
 808 #if 0
 809 /*
 810  * when dropping snapshots, we generate a ton of delayed refs, and it makes
 811  * sense not to join the transaction while it is trying to flush the current
 812  * queue of delayed refs out.
 813  *
 814  * This is used by the drop snapshot code only
 815  */
 816 static noinline int wait_transaction_pre_flush(struct btrfs_fs_info *info)
 817 {
 818         DEFINE_WAIT(wait);
 819
 820         mutex_lock(&info->trans_mutex);
 821         while (info->running_transaction &&
 822                info->running_transaction->delayed_refs.flushing) {
 823                 prepare_to_wait(&info->transaction_wait, &wait,
 824                                 TASK_UNINTERRUPTIBLE);
 825                 mutex_unlock(&info->trans_mutex);
 826
 827                 schedule();
 828
 829                 mutex_lock(&info->trans_mutex);
 830                 finish_wait(&info->transaction_wait, &wait);
 831         }
 832         mutex_unlock(&info->trans_mutex);
 833         return 0;
 834 }
 835
 836 /*
 837  * Given a list of roots that need to be deleted, call btrfs_drop_snapshot on
 838  * all of them
 839  */
 840 int btrfs_drop_dead_root(struct btrfs_root *root)
 841 {
 842         struct btrfs_trans_handle *trans;
 843         struct btrfs_root *tree_root = root->fs_info->tree_root;
 844         unsigned long nr;
 845         int ret;
 846
 847         while (1) {
 848                 /*
 849                  * we don't want to jump in and create a bunch of
 850                  * delayed refs if the transaction is starting to close
 851                  */
 852                 wait_transaction_pre_flush(tree_root->fs_info);
 853                 trans = btrfs_start_transaction(tree_root, 1);
 854
 855                 /*
 856                  * we've joined a transaction, make sure it isn't
 857                  * closing right now
 858                  */
 859                 if (trans->transaction->delayed_refs.flushing) {
 860                         btrfs_end_transaction(trans, tree_root);
 861                         continue;
 862                 }
 863
 864                 ret = btrfs_drop_snapshot(trans, root);
 865                 if (ret != -EAGAIN)
 866                         break;
 867
 868                 ret = btrfs_update_root(trans, tree_root,
 869                                         &root->root_key,
 870                                         &root->root_item);
 871                 if (ret)
 872                         break;
 873
 874                 nr = trans->blocks_used;
 875                 ret = btrfs_end_transaction(trans, tree_root);
 876                 BUG_ON(ret);
 877
 878                 btrfs_btree_balance_dirty(tree_root, nr);
 879                 cond_resched();
 880         }
 881         BUG_ON(ret);
 882
 883         ret = btrfs_del_root(trans, tree_root, &root->root_key);
 884         BUG_ON(ret);
 885
 886         nr = trans->blocks_used;
 887         ret = btrfs_end_transaction(trans, tree_root);
 888         BUG_ON(ret);
 889
 890         free_extent_buffer(root->node);
 891         free_extent_buffer(root->commit_root);
 892         kfree(root);
 893
 894         btrfs_btree_balance_dirty(tree_root, nr);
 895         return ret;
 896 }
 897 #endif
 898
 899 /*
 900  * new snapshots need to be created at a very specific time in the
 901  * transaction commit.  This does the actual creation
 902  */
 903 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 904                                    struct btrfs_fs_info *fs_info,
 905                                    struct btrfs_pending_snapshot *pending)
 906 {
 907         struct btrfs_key key;
 908         struct btrfs_root_item *new_root_item;
 909         struct btrfs_root *tree_root = fs_info->tree_root;
 910         struct btrfs_root *root = pending->root;
 911         struct btrfs_root *parent_root;
 912         struct inode *parent_inode;
 913         struct dentry *parent;
 914         struct dentry *dentry;
 915         struct extent_buffer *tmp;
 916         struct extent_buffer *old;
 917         int ret;
 918         u64 to_reserve = 0;
 919         u64 index = 0;
 920         u64 objectid;
 921         u64 root_flags;
 922
 923         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 924         if (!new_root_item) {
 925                 pending->error = -ENOMEM;
 926                 goto fail;
 927         }
 928
 929         ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
 930         if (ret) {
 931                 pending->error = ret;
 932                 goto fail;
 933         }
 934
 935         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
 936         btrfs_orphan_pre_snapshot(trans, pending, &to_reserve);
 937
 938         if (to_reserve > 0) {
 939                 ret = btrfs_block_rsv_add(trans, root, &pending->block_rsv,
 940                                           to_reserve);
 941                 if (ret) {
 942                         pending->error = ret;
 943                         goto fail;
 944                 }
 945         }
 946
 947         key.objectid = objectid;
 948         key.offset = (u64)-1;
 949         key.type = BTRFS_ROOT_ITEM_KEY;
 950
 951         trans->block_rsv = &pending->block_rsv;
 952
 953         dentry = pending->dentry;
 954         parent = dget_parent(dentry);
 955         parent_inode = parent->d_inode;
 956         parent_root = BTRFS_I(parent_inode)->root;
 957         record_root_in_trans(trans, parent_root);
 958
 959         /*
 960          * insert the directory item
 961          */
 962         ret = btrfs_set_inode_index(parent_inode, &index);
 963         BUG_ON(ret);
 964         ret = btrfs_insert_dir_item(trans, parent_root,
 965                                 dentry->d_name.name, dentry->d_name.len,
 966                                 parent_inode->i_ino, &key,
 967                                 BTRFS_FT_DIR, index);
 968         BUG_ON(ret);
 969
 970         btrfs_i_size_write(parent_inode, parent_inode->i_size +
 971                                          dentry->d_name.len * 2);
 972         ret = btrfs_update_inode(trans, parent_root, parent_inode);
 973         BUG_ON(ret);
 974
 975         record_root_in_trans(trans, root);
 976         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
 977         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
 978
 979         root_flags = btrfs_root_flags(new_root_item);
 980         if (pending->readonly)
 981                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
 982         else
 983                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
 984         btrfs_set_root_flags(new_root_item, root_flags);
 985
 986         old = btrfs_lock_root_node(root);
 987         btrfs_cow_block(trans, root, old, NULL, 0, &old);
 988         btrfs_set_lock_blocking(old);
 989
 990         btrfs_copy_root(trans, root, old, &tmp, objectid);
 991         btrfs_tree_unlock(old);
 992         free_extent_buffer(old);
 993
 994         btrfs_set_root_node(new_root_item, tmp);
 995         /* record when the snapshot was created in key.offset */
 996         key.offset = trans->transid;
 997         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
 998         btrfs_tree_unlock(tmp);
 999         free_extent_buffer(tmp);
1000         BUG_ON(ret);
1001
1002         /*
1003          * insert root back/forward references
1004          */
1005         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1006                                  parent_root->root_key.objectid,
1007                                  parent_inode->i_ino, index,
1008                                  dentry->d_name.name, dentry->d_name.len);
1009         BUG_ON(ret);
1010         dput(parent);
1011
1012         key.offset = (u64)-1;
1013         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1014         BUG_ON(IS_ERR(pending->snap));
1015
1016         btrfs_reloc_post_snapshot(trans, pending);
1017         btrfs_orphan_post_snapshot(trans, pending);
1018 fail:
1019         kfree(new_root_item);
1020         btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
1021         return 0;
1022 }
1023
1024 /*
1025  * create all the snapshots we've scheduled for creation
1026  */
1027 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1028                                              struct btrfs_fs_info *fs_info)
1029 {
1030         struct btrfs_pending_snapshot *pending;
1031         struct list_head *head = &trans->transaction->pending_snapshots;
1032         int ret;
1033
1034         list_for_each_entry(pending, head, list) {
1035                 ret = create_pending_snapshot(trans, fs_info, pending);
1036                 BUG_ON(ret);
1037         }
1038         return 0;
1039 }
1040
1041 static void update_super_roots(struct btrfs_root *root)
1042 {
1043         struct btrfs_root_item *root_item;
1044         struct btrfs_super_block *super;
1045
1046         super = &root->fs_info->super_copy;
1047
1048         root_item = &root->fs_info->chunk_root->root_item;
1049         super->chunk_root = root_item->bytenr;
1050         super->chunk_root_generation = root_item->generation;
1051         super->chunk_root_level = root_item->level;
1052
1053         root_item = &root->fs_info->tree_root->root_item;
1054         super->root = root_item->bytenr;
1055         super->generation = root_item->generation;
1056         super->root_level = root_item->level;
1057         if (super->cache_generation != 0 || btrfs_test_opt(root, SPACE_CACHE))
1058                 super->cache_generation = root_item->generation;
1059 }
1060
1061 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1062 {
1063         int ret = 0;
1064         spin_lock(&info->new_trans_lock);
1065         if (info->running_transaction)
1066                 ret = info->running_transaction->in_commit;
1067         spin_unlock(&info->new_trans_lock);
1068         return ret;
1069 }
1070
1071 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1072 {
1073         int ret = 0;
1074         spin_lock(&info->new_trans_lock);
1075         if (info->running_transaction)
1076                 ret = info->running_transaction->blocked;
1077         spin_unlock(&info->new_trans_lock);
1078         return ret;
1079 }
1080
1081 /*
1082  * wait for the current transaction commit to start and block subsequent
1083  * transaction joins
1084  */
1085 static void wait_current_trans_commit_start(struct btrfs_root *root,
1086                                             struct btrfs_transaction *trans)
1087 {
1088         DEFINE_WAIT(wait);
1089
1090         if (trans->in_commit)
1091                 return;
1092
1093         while (1) {
1094                 prepare_to_wait(&root->fs_info->transaction_blocked_wait, &wait,
1095                                 TASK_UNINTERRUPTIBLE);
1096                 if (trans->in_commit) {
1097                         finish_wait(&root->fs_info->transaction_blocked_wait,
1098                                     &wait);
1099                         break;
1100                 }
1101                 mutex_unlock(&root->fs_info->trans_mutex);
1102                 schedule();
1103                 mutex_lock(&root->fs_info->trans_mutex);
1104                 finish_wait(&root->fs_info->transaction_blocked_wait, &wait);
1105         }
1106 }
1107
1108 /*
1109  * wait for the current transaction to start and then become unblocked.
1110  * caller holds ref.
1111  */
1112 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1113                                          struct btrfs_transaction *trans)
1114 {
1115         DEFINE_WAIT(wait);
1116
1117         if (trans->commit_done || (trans->in_commit && !trans->blocked))
1118                 return;
1119
1120         while (1) {
1121                 prepare_to_wait(&root->fs_info->transaction_wait, &wait,
1122                                 TASK_UNINTERRUPTIBLE);
1123                 if (trans->commit_done ||
1124                     (trans->in_commit && !trans->blocked)) {
1125                         finish_wait(&root->fs_info->transaction_wait,
1126                                     &wait);
1127                         break;
1128                 }
1129                 mutex_unlock(&root->fs_info->trans_mutex);
1130                 schedule();
1131                 mutex_lock(&root->fs_info->trans_mutex);
1132                 finish_wait(&root->fs_info->transaction_wait,
1133                             &wait);
1134         }
1135 }
1136
1137 /*
1138  * commit transactions asynchronously. once btrfs_commit_transaction_async
1139  * returns, any subsequent transaction will not be allowed to join.
1140  */
1141 struct btrfs_async_commit {
1142         struct btrfs_trans_handle *newtrans;
1143         struct btrfs_root *root;
1144         struct delayed_work work;
1145 };
1146
1147 static void do_async_commit(struct work_struct *work)
1148 {
1149         struct btrfs_async_commit *ac =
1150                 container_of(work, struct btrfs_async_commit, work.work);
1151
1152         btrfs_commit_transaction(ac->newtrans, ac->root);
1153         kfree(ac);
1154 }
1155
1156 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1157                                    struct btrfs_root *root,
1158                                    int wait_for_unblock)
1159 {
1160         struct btrfs_async_commit *ac;
1161         struct btrfs_transaction *cur_trans;
1162
1163         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1164         if (!ac)
1165                 return -ENOMEM;
1166
1167         INIT_DELAYED_WORK(&ac->work, do_async_commit);
1168         ac->root = root;
1169         ac->newtrans = btrfs_join_transaction(root, 0);
1170         if (IS_ERR(ac->newtrans)) {
1171                 int err = PTR_ERR(ac->newtrans);
1172                 kfree(ac);
1173                 return err;
1174         }
1175
1176         /* take transaction reference */
1177         mutex_lock(&root->fs_info->trans_mutex);
1178         cur_trans = trans->transaction;
1179         cur_trans->use_count++;
1180         mutex_unlock(&root->fs_info->trans_mutex);
1181
1182         btrfs_end_transaction(trans, root);
1183         schedule_delayed_work(&ac->work, 0);
1184
1185         /* wait for transaction to start and unblock */
1186         mutex_lock(&root->fs_info->trans_mutex);
1187         if (wait_for_unblock)
1188                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1189         else
1190                 wait_current_trans_commit_start(root, cur_trans);
1191         put_transaction(cur_trans);
1192         mutex_unlock(&root->fs_info->trans_mutex);
1193
1194         return 0;
1195 }
1196
1197 /*
1198  * btrfs_transaction state sequence:
1199  *    in_commit = 0, blocked = 0  (initial)
1200  *    in_commit = 1, blocked = 1
1201  *    blocked = 0
1202  *    commit_done = 1
1203  */
1204 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1205                              struct btrfs_root *root)
1206 {
1207         unsigned long joined = 0;
1208         struct btrfs_transaction *cur_trans;
1209         struct btrfs_transaction *prev_trans = NULL;
1210         DEFINE_WAIT(wait);
1211         int ret;
1212         int should_grow = 0;
1213         unsigned long now = get_seconds();
1214         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1215
1216         btrfs_run_ordered_operations(root, 0);
1217
1218         /* make a pass through all the delayed refs we have so far
1219          * any runnings procs may add more while we are here
1220          */
1221         ret = btrfs_run_delayed_refs(trans, root, 0);
1222         BUG_ON(ret);
1223
1224         btrfs_trans_release_metadata(trans, root);
1225
1226         cur_trans = trans->transaction;
1227         /*
1228          * set the flushing flag so procs in this transaction have to
1229          * start sending their work down.
1230          */
1231         cur_trans->delayed_refs.flushing = 1;
1232
1233         ret = btrfs_run_delayed_refs(trans, root, 0);
1234         BUG_ON(ret);
1235
1236         mutex_lock(&root->fs_info->trans_mutex);
1237         if (cur_trans->in_commit) {
1238                 cur_trans->use_count++;
1239                 mutex_unlock(&root->fs_info->trans_mutex);
1240                 btrfs_end_transaction(trans, root);
1241
1242                 ret = wait_for_commit(root, cur_trans);
1243                 BUG_ON(ret);
1244
1245                 mutex_lock(&root->fs_info->trans_mutex);
1246                 put_transaction(cur_trans);
1247                 mutex_unlock(&root->fs_info->trans_mutex);
1248
1249                 return 0;
1250         }
1251
1252         trans->transaction->in_commit = 1;
1253         trans->transaction->blocked = 1;
1254         wake_up(&root->fs_info->transaction_blocked_wait);
1255
1256         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1257                 prev_trans = list_entry(cur_trans->list.prev,
1258                                         struct btrfs_transaction, list);
1259                 if (!prev_trans->commit_done) {
1260                         prev_trans->use_count++;
1261                         mutex_unlock(&root->fs_info->trans_mutex);
1262
1263                         wait_for_commit(root, prev_trans);
1264
1265                         mutex_lock(&root->fs_info->trans_mutex);
1266                         put_transaction(prev_trans);
1267                 }
1268         }
1269
1270         if (now < cur_trans->start_time || now - cur_trans->start_time < 1)
1271                 should_grow = 1;
1272
1273         do {
1274                 int snap_pending = 0;
1275                 joined = cur_trans->num_joined;
1276                 if (!list_empty(&trans->transaction->pending_snapshots))
1277                         snap_pending = 1;
1278
1279                 WARN_ON(cur_trans != trans->transaction);
1280                 mutex_unlock(&root->fs_info->trans_mutex);
1281
1282                 if (flush_on_commit || snap_pending) {
1283                         btrfs_start_delalloc_inodes(root, 1);
1284                         ret = btrfs_wait_ordered_extents(root, 0, 1);
1285                         BUG_ON(ret);
1286                 }
1287
1288                 /*
1289                  * rename don't use btrfs_join_transaction, so, once we
1290                  * set the transaction to blocked above, we aren't going
1291                  * to get any new ordered operations.  We can safely run
1292                  * it here and no for sure that nothing new will be added
1293                  * to the list
1294                  */
1295                 btrfs_run_ordered_operations(root, 1);
1296
1297                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1298                                 TASK_UNINTERRUPTIBLE);
1299
1300                 smp_mb();
1301                 if (cur_trans->num_writers > 1)
1302                         schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1303                 else if (should_grow)
1304                         schedule_timeout(1);
1305
1306                 mutex_lock(&root->fs_info->trans_mutex);
1307                 finish_wait(&cur_trans->writer_wait, &wait);
1308         } while (cur_trans->num_writers > 1 ||
1309                  (should_grow && cur_trans->num_joined != joined));
1310
1311         ret = create_pending_snapshots(trans, root->fs_info);
1312         BUG_ON(ret);
1313
1314         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1315         BUG_ON(ret);
1316
1317         WARN_ON(cur_trans != trans->transaction);
1318
1319         /* btrfs_commit_tree_roots is responsible for getting the
1320          * various roots consistent with each other.  Every pointer
1321          * in the tree of tree roots has to point to the most up to date
1322          * root for every subvolume and other tree.  So, we have to keep
1323          * the tree logging code from jumping in and changing any
1324          * of the trees.
1325          *
1326          * At this point in the commit, there can't be any tree-log
1327          * writers, but a little lower down we drop the trans mutex
1328          * and let new people in.  By holding the tree_log_mutex
1329          * from now until after the super is written, we avoid races
1330          * with the tree-log code.
1331          */
1332         mutex_lock(&root->fs_info->tree_log_mutex);
1333
1334         ret = commit_fs_roots(trans, root);
1335         BUG_ON(ret);
1336
1337         /* commit_fs_roots gets rid of all the tree log roots, it is now
1338          * safe to free the root of tree log roots
1339          */
1340         btrfs_free_log_root_tree(trans, root->fs_info);
1341
1342         ret = commit_cowonly_roots(trans, root);
1343         BUG_ON(ret);
1344
1345         btrfs_prepare_extent_commit(trans, root);
1346
1347         cur_trans = root->fs_info->running_transaction;
1348         spin_lock(&root->fs_info->new_trans_lock);
1349         root->fs_info->running_transaction = NULL;
1350         spin_unlock(&root->fs_info->new_trans_lock);
1351
1352         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1353                             root->fs_info->tree_root->node);
1354         switch_commit_root(root->fs_info->tree_root);
1355
1356         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1357                             root->fs_info->chunk_root->node);
1358         switch_commit_root(root->fs_info->chunk_root);
1359
1360         update_super_roots(root);
1361
1362         if (!root->fs_info->log_root_recovering) {
1363                 btrfs_set_super_log_root(&root->fs_info->super_copy, 0);
1364                 btrfs_set_super_log_root_level(&root->fs_info->super_copy, 0);
1365         }
1366
1367         memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
1368                sizeof(root->fs_info->super_copy));
1369
1370         trans->transaction->blocked = 0;
1371
1372         wake_up(&root->fs_info->transaction_wait);
1373
1374         mutex_unlock(&root->fs_info->trans_mutex);
1375         ret = btrfs_write_and_wait_transaction(trans, root);
1376         BUG_ON(ret);
1377         write_ctree_super(trans, root, 0);
1378
1379         /*
1380          * the super is written, we can safely allow the tree-loggers
1381          * to go about their business
1382          */
1383         mutex_unlock(&root->fs_info->tree_log_mutex);
1384
1385         btrfs_finish_extent_commit(trans, root);
1386
1387         mutex_lock(&root->fs_info->trans_mutex);
1388
1389         cur_trans->commit_done = 1;
1390
1391         root->fs_info->last_trans_committed = cur_trans->transid;
1392
1393         wake_up(&cur_trans->commit_wait);
1394
1395         put_transaction(cur_trans);
1396         put_transaction(cur_trans);
1397
1398         trace_btrfs_transaction_commit(root);
1399
1400         mutex_unlock(&root->fs_info->trans_mutex);
1401
1402         if (current->journal_info == trans)
1403                 current->journal_info = NULL;
1404
1405         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1406
1407         if (current != root->fs_info->transaction_kthread)
1408                 btrfs_run_delayed_iputs(root);
1409
1410         return ret;
1411 }
1412
1413 /*
1414  * interface function to delete all the snapshots we have scheduled for deletion
1415  */
1416 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1417 {
1418         LIST_HEAD(list);
1419         struct btrfs_fs_info *fs_info = root->fs_info;
1420
1421         mutex_lock(&fs_info->trans_mutex);
1422         list_splice_init(&fs_info->dead_roots, &list);
1423         mutex_unlock(&fs_info->trans_mutex);
1424
1425         while (!list_empty(&list)) {
1426                 root = list_entry(list.next, struct btrfs_root, root_list);
1427                 list_del(&root->root_list);
1428
1429                 if (btrfs_header_backref_rev(root->node) <
1430                     BTRFS_MIXED_BACKREF_REV)
1431                         btrfs_drop_snapshot(root, NULL, 0);
1432                 else
1433                         btrfs_drop_snapshot(root, NULL, 1);
1434         }
1435         return 0;
1436 }