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