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