fs/btrfs/transaction.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/slab.h>
  21 #include <linux/sched.h>
  22 #include <linux/writeback.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/blkdev.h>
  25 #include "ctree.h"
  26 #include "disk-io.h"
  27 #include "transaction.h"
  28 #include "locking.h"
  29 #include "tree-log.h"
  30
  31 #define BTRFS_ROOT_TRANS_TAG 0
  32
  33 static noinline void put_transaction(struct btrfs_transaction *transaction)
  34 {
  35         WARN_ON(transaction->use_count == 0);
  36         transaction->use_count--;
  37         if (transaction->use_count == 0) {
  38                 list_del_init(&transaction->list);
  39                 memset(transaction, 0, sizeof(*transaction));
  40                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  41         }
  42 }
  43
  44 static noinline void switch_commit_root(struct btrfs_root *root)
  45 {
  46         free_extent_buffer(root->commit_root);
  47         root->commit_root = btrfs_root_node(root);
  48 }
  49
  50 /*
  51  * either allocate a new transaction or hop into the existing one
  52  */
  53 static noinline int join_transaction(struct btrfs_root *root)
  54 {
  55         struct btrfs_transaction *cur_trans;
  56         cur_trans = root->fs_info->running_transaction;
  57         if (!cur_trans) {
  58                 cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
  59                                              GFP_NOFS);
  60                 if (!cur_trans)
  61                         return -ENOMEM;
  62                 root->fs_info->generation++;
  63                 cur_trans->num_writers = 1;
  64                 cur_trans->num_joined = 0;
  65                 cur_trans->transid = root->fs_info->generation;
  66                 init_waitqueue_head(&cur_trans->writer_wait);
  67                 init_waitqueue_head(&cur_trans->commit_wait);
  68                 cur_trans->in_commit = 0;
  69                 cur_trans->blocked = 0;
  70                 cur_trans->use_count = 1;
  71                 cur_trans->commit_done = 0;
  72                 cur_trans->start_time = get_seconds();
  73
  74                 cur_trans->delayed_refs.root = RB_ROOT;
  75                 cur_trans->delayed_refs.num_entries = 0;
  76                 cur_trans->delayed_refs.num_heads_ready = 0;
  77                 cur_trans->delayed_refs.num_heads = 0;
  78                 cur_trans->delayed_refs.flushing = 0;
  79                 cur_trans->delayed_refs.run_delayed_start = 0;
  80                 spin_lock_init(&cur_trans->delayed_refs.lock);
  81
  82                 INIT_LIST_HEAD(&cur_trans->pending_snapshots);
  83                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
  84                 extent_io_tree_init(&cur_trans->dirty_pages,
  85                                      root->fs_info->btree_inode->i_mapping,
  86                                      GFP_NOFS);
  87                 spin_lock(&root->fs_info->new_trans_lock);
  88                 root->fs_info->running_transaction = cur_trans;
  89                 spin_unlock(&root->fs_info->new_trans_lock);
  90         } else {
  91                 cur_trans->num_writers++;
  92                 cur_trans->num_joined++;
  93         }
  94
  95         return 0;
  96 }
  97
  98 /*
  99  * this does all the record keeping required to make sure that a reference
 100  * counted root is properly recorded in a given transaction.  This is required
 101  * to make sure the old root from before we joined the transaction is deleted
 102  * when the transaction commits
 103  */
 104 static noinline int record_root_in_trans(struct btrfs_trans_handle *trans,
 105                                          struct btrfs_root *root)
 106 {
 107         if (root->ref_cows && root->last_trans < trans->transid) {
 108                 WARN_ON(root == root->fs_info->extent_root);
 109                 WARN_ON(root->commit_root != root->node);
 110
 111                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 112                            (unsigned long)root->root_key.objectid,
 113                            BTRFS_ROOT_TRANS_TAG);
 114                 root->last_trans = trans->transid;
 115                 btrfs_init_reloc_root(trans, root);
 116         }
 117         return 0;
 118 }
 119
 120 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 121                                struct btrfs_root *root)
 122 {
 123         if (!root->ref_cows)
 124                 return 0;
 125
 126         mutex_lock(&root->fs_info->trans_mutex);
 127         if (root->last_trans == trans->transid) {
 128                 mutex_unlock(&root->fs_info->trans_mutex);
 129                 return 0;
 130         }
 131
 132         record_root_in_trans(trans, root);
 133         mutex_unlock(&root->fs_info->trans_mutex);
 134         return 0;
 135 }
 136
 137 /* wait for commit against the current transaction to become unblocked
 138  * when this is done, it is safe to start a new transaction, but the current
 139  * transaction might not be fully on disk.
 140  */
 141 static void wait_current_trans(struct btrfs_root *root)
 142 {
 143         struct btrfs_transaction *cur_trans;
 144
 145         cur_trans = root->fs_info->running_transaction;
 146         if (cur_trans && cur_trans->blocked) {
 147                 DEFINE_WAIT(wait);
 148                 cur_trans->use_count++;
 149                 while (1) {
 150                         prepare_to_wait(&root->fs_info->transaction_wait, &wait,
 151                                         TASK_UNINTERRUPTIBLE);
 152                         if (!cur_trans->blocked)
 153                                 break;
 154                         mutex_unlock(&root->fs_info->trans_mutex);
 155                         schedule();
 156                         mutex_lock(&root->fs_info->trans_mutex);
 157                 }
 158                 finish_wait(&root->fs_info->transaction_wait, &wait);
 159                 put_transaction(cur_trans);
 160         }
 161 }
 162
 163 enum btrfs_trans_type {
 164         TRANS_START,
 165         TRANS_JOIN,
 166         TRANS_USERSPACE,
 167         TRANS_JOIN_NOLOCK,
 168 };
 169
 170 static int may_wait_transaction(struct btrfs_root *root, int type)
 171 {
 172         if (!root->fs_info->log_root_recovering &&
 173             ((type == TRANS_START && !root->fs_info->open_ioctl_trans) ||
 174              type == TRANS_USERSPACE))
 175                 return 1;
 176         return 0;
 177 }
 178
 179 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 180                                                     u64 num_items, int type)
 181 {
 182         struct btrfs_trans_handle *h;
 183         struct btrfs_transaction *cur_trans;
 184         int ret;
 185
 186         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
 187                 return ERR_PTR(-EROFS);
 188 again:
 189         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 190         if (!h)
 191                 return ERR_PTR(-ENOMEM);
 192
 193         if (type != TRANS_JOIN_NOLOCK)
 194                 mutex_lock(&root->fs_info->trans_mutex);
 195         if (may_wait_transaction(root, type))
 196                 wait_current_trans(root);
 197
 198         ret = join_transaction(root);
 199         if (ret < 0) {
 200                 kmem_cache_free(btrfs_trans_handle_cachep, h);
 201                 if (type != TRANS_JOIN_NOLOCK)
 202                         mutex_unlock(&root->fs_info->trans_mutex);
 203                 return ERR_PTR(ret);
 204         }
 205
 206         cur_trans = root->fs_info->running_transaction;
 207         cur_trans->use_count++;
 208         if (type != TRANS_JOIN_NOLOCK)
 209                 mutex_unlock(&root->fs_info->trans_mutex);
 210
 211         h->transid = cur_trans->transid;
 212         h->transaction = cur_trans;
 213         h->blocks_used = 0;
 214         h->block_group = 0;
 215         h->bytes_reserved = 0;
 216         h->delayed_ref_updates = 0;
 217         h->block_rsv = NULL;
 218
 219         smp_mb();
 220         if (cur_trans->blocked && may_wait_transaction(root, type)) {
 221                 btrfs_commit_transaction(h, root);
 222                 goto again;
 223         }
 224
 225         if (num_items > 0) {
 226                 ret = btrfs_trans_reserve_metadata(h, root, num_items);
 227                 if (ret == -EAGAIN) {
 228                         btrfs_commit_transaction(h, root);
 229                         goto again;
 230                 }
 231                 if (ret < 0) {
 232                         btrfs_end_transaction(h, root);
 233                         return ERR_PTR(ret);
 234                 }
 235         }
 236
 237         if (type != TRANS_JOIN_NOLOCK)
 238                 mutex_lock(&root->fs_info->trans_mutex);
 239         record_root_in_trans(h, root);
 240         if (type != TRANS_JOIN_NOLOCK)
 241                 mutex_unlock(&root->fs_info->trans_mutex);
 242
 243         if (!current->journal_info && type != TRANS_USERSPACE)
 244                 current->journal_info = h;
 245         return h;
 246 }
 247
 248 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 249                                                    int num_items)
 250 {
 251         return start_transaction(root, num_items, TRANS_START);
 252 }
 253 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
 254                                                    int num_blocks)
 255 {
 256         return start_transaction(root, 0, TRANS_JOIN);
 257 }
 258
 259 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root,
 260                                                           int num_blocks)
 261 {
 262         return start_transaction(root, 0, TRANS_JOIN_NOLOCK);
 263 }
 264
 265 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *r,
 266                                                          int num_blocks)
 267 {
 268         return start_transaction(r, 0, TRANS_USERSPACE);
 269 }
 270
 271 /* wait for a transaction commit to be fully complete */
 272 static noinline int wait_for_commit(struct btrfs_root *root,
 273                                     struct btrfs_transaction *commit)
 274 {
 275         DEFINE_WAIT(wait);
 276         mutex_lock(&root->fs_info->trans_mutex);
 277         while (!commit->commit_done) {
 278                 prepare_to_wait(&commit->commit_wait, &wait,
 279                                 TASK_UNINTERRUPTIBLE);
 280                 if (commit->commit_done)
 281                         break;
 282                 mutex_unlock(&root->fs_info->trans_mutex);
 283                 schedule();
 284                 mutex_lock(&root->fs_info->trans_mutex);
 285         }
 286         mutex_unlock(&root->fs_info->trans_mutex);
 287         finish_wait(&commit->commit_wait, &wait);
 288         return 0;
 289 }
 290
 291 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 292 {
 293         struct btrfs_transaction *cur_trans = NULL, *t;
 294         int ret;
 295
 296         mutex_lock(&root->fs_info->trans_mutex);
 297
 298         ret = 0;
 299         if (transid) {
 300                 if (transid <= root->fs_info->last_trans_committed)
 301                         goto out_unlock;
 302
 303                 /* find specified transaction */
 304                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 305                         if (t->transid == transid) {
 306                                 cur_trans = t;
 307                                 break;
 308                         }
 309                         if (t->transid > transid)
 310                                 break;
 311                 }
 312                 ret = -EINVAL;
 313                 if (!cur_trans)
 314                         goto out_unlock;  /* bad transid */
 315         } else {
 316                 /* find newest transaction that is committing | committed */
 317                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 318                                             list) {
 319                         if (t->in_commit) {
 320                                 if (t->commit_done)
 321                                         goto out_unlock;
 322                                 cur_trans = t;
 323                                 break;
 324                         }
 325                 }
 326                 if (!cur_trans)
 327                         goto out_unlock;  /* nothing committing|committed */
 328         }
 329
 330         cur_trans->use_count++;
 331         mutex_unlock(&root->fs_info->trans_mutex);
 332
 333         wait_for_commit(root, cur_trans);
 334
 335         mutex_lock(&root->fs_info->trans_mutex);
 336         put_transaction(cur_trans);
 337         ret = 0;
 338 out_unlock:
 339         mutex_unlock(&root->fs_info->trans_mutex);
 340         return ret;
 341 }
 342
 343 #if 0
 344 /*
 345  * rate limit against the drop_snapshot code.  This helps to slow down new
 346  * operations if the drop_snapshot code isn't able to keep up.
 347  */
 348 static void throttle_on_drops(struct btrfs_root *root)
 349 {
 350         struct btrfs_fs_info *info = root->fs_info;
 351         int harder_count = 0;
 352
 353 harder:
 354         if (atomic_read(&info->throttles)) {
 355                 DEFINE_WAIT(wait);
 356                 int thr;
 357                 thr = atomic_read(&info->throttle_gen);
 358
 359                 do {
 360                         prepare_to_wait(&info->transaction_throttle,
 361                                         &wait, TASK_UNINTERRUPTIBLE);
 362                         if (!atomic_read(&info->throttles)) {
 363                                 finish_wait(&info->transaction_throttle, &wait);
 364                                 break;
 365                         }
 366                         schedule();
 367                         finish_wait(&info->transaction_throttle, &wait);
 368                 } while (thr == atomic_read(&info->throttle_gen));
 369                 harder_count++;
 370
 371                 if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
 372                     harder_count < 2)
 373                         goto harder;
 374
 375                 if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
 376                     harder_count < 10)
 377                         goto harder;
 378
 379                 if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
 380                     harder_count < 20)
 381                         goto harder;
 382         }
 383 }
 384 #endif
 385
 386 void btrfs_throttle(struct btrfs_root *root)
 387 {
 388         mutex_lock(&root->fs_info->trans_mutex);
 389         if (!root->fs_info->open_ioctl_trans)
 390                 wait_current_trans(root);
 391         mutex_unlock(&root->fs_info->trans_mutex);
 392 }
 393
 394 static int should_end_transaction(struct btrfs_trans_handle *trans,
 395                                   struct btrfs_root *root)
 396 {
 397         int ret;
 398         ret = btrfs_block_rsv_check(trans, root,
 399                                     &root->fs_info->global_block_rsv, 0, 5);
 400         return ret ? 1 : 0;
 401 }
 402
 403 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 404                                  struct btrfs_root *root)
 405 {
 406         struct btrfs_transaction *cur_trans = trans->transaction;
 407         int updates;
 408
 409         if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
 410                 return 1;
 411
 412         updates = trans->delayed_ref_updates;
 413         trans->delayed_ref_updates = 0;
 414         if (updates)
 415                 btrfs_run_delayed_refs(trans, root, updates);
 416
 417         return should_end_transaction(trans, root);
 418 }
 419
 420 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 421                           struct btrfs_root *root, int throttle, int lock)
 422 {
 423         struct btrfs_transaction *cur_trans = trans->transaction;
 424         struct btrfs_fs_info *info = root->fs_info;
 425         int count = 0;
 426
 427         while (count < 4) {
 428                 unsigned long cur = trans->delayed_ref_updates;
 429                 trans->delayed_ref_updates = 0;
 430                 if (cur &&
 431                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 432                         trans->delayed_ref_updates = 0;
 433
 434                         /*
 435                          * do a full flush if the transaction is trying
 436                          * to close
 437                          */
 438                         if (trans->transaction->delayed_refs.flushing)
 439                                 cur = 0;
 440                         btrfs_run_delayed_refs(trans, root, cur);
 441                 } else {
 442                         break;
 443                 }
 444                 count++;
 445         }
 446
 447         btrfs_trans_release_metadata(trans, root);
 448
 449         if (lock && !root->fs_info->open_ioctl_trans &&
 450             should_end_transaction(trans, root))
 451                 trans->transaction->blocked = 1;
 452
 453         if (lock && cur_trans->blocked && !cur_trans->in_commit) {
 454                 if (throttle)
 455                         return btrfs_commit_transaction(trans, root);
 456                 else
 457                         wake_up_process(info->transaction_kthread);
 458         }
 459
 460         if (lock)
 461                 mutex_lock(&info->trans_mutex);
 462         WARN_ON(cur_trans != info->running_transaction);
 463         WARN_ON(cur_trans->num_writers < 1);
 464         cur_trans->num_writers--;
 465
 466         smp_mb();
 467         if (waitqueue_active(&cur_trans->writer_wait))
 468                 wake_up(&cur_trans->writer_wait);
 469         put_transaction(cur_trans);
 470         if (lock)
 471                 mutex_unlock(&info->trans_mutex);
 472
 473         if (current->journal_info == trans)
 474                 current->journal_info = NULL;
 475         memset(trans, 0, sizeof(*trans));
 476         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 477
 478         if (throttle)
 479                 btrfs_run_delayed_iputs(root);
 480
 481         return 0;
 482 }
 483
 484 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 485                           struct btrfs_root *root)
 486 {
 487         return __btrfs_end_transaction(trans, root, 0, 1);
 488 }
 489
 490 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 491                                    struct btrfs_root *root)
 492 {
 493         return __btrfs_end_transaction(trans, root, 1, 1);
 494 }
 495
 496 int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
 497                                  struct btrfs_root *root)
 498 {
 499         return __btrfs_end_transaction(trans, root, 0, 0);
 500 }
 501
 502 /*
 503  * when btree blocks are allocated, they have some corresponding bits set for
 504  * them in one of two extent_io trees.  This is used to make sure all of
 505  * those extents are sent to disk but does not wait on them
 506  */
 507 int btrfs_write_marked_extents(struct btrfs_root *root,
 508                                struct extent_io_tree *dirty_pages, int mark)
 509 {
 510         int ret;
 511         int err = 0;
 512         int werr = 0;
 513         struct page *page;
 514         struct inode *btree_inode = root->fs_info->btree_inode;
 515         u64 start = 0;
 516         u64 end;
 517         unsigned long index;
 518
 519         while (1) {
 520                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 521                                             mark);
 522                 if (ret)
 523                         break;
 524                 while (start <= end) {
 525                         cond_resched();
 526
 527                         index = start >> PAGE_CACHE_SHIFT;
 528                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 529                         page = find_get_page(btree_inode->i_mapping, index);
 530                         if (!page)
 531                                 continue;
 532
 533                         btree_lock_page_hook(page);
 534                         if (!page->mapping) {
 535                                 unlock_page(page);
 536                                 page_cache_release(page);
 537                                 continue;
 538                         }
 539
 540                         if (PageWriteback(page)) {
 541                                 if (PageDirty(page))
 542                                         wait_on_page_writeback(page);
 543                                 else {
 544                                         unlock_page(page);
 545                                         page_cache_release(page);
 546                                         continue;
 547                                 }
 548                         }
 549                         err = write_one_page(page, 0);
 550                         if (err)
 551                                 werr = err;
 552                         page_cache_release(page);
 553                 }
 554         }
 555         if (err)
 556                 werr = err;
 557         return werr;
 558 }
 559
 560 /*
 561  * when btree blocks are allocated, they have some corresponding bits set for
 562  * them in one of two extent_io trees.  This is used to make sure all of
 563  * those extents are on disk for transaction or log commit.  We wait
 564  * on all the pages and clear them from the dirty pages state tree
 565  */
 566 int btrfs_wait_marked_extents(struct btrfs_root *root,
 567                               struct extent_io_tree *dirty_pages, int mark)
 568 {
 569         int ret;
 570         int err = 0;
 571         int werr = 0;
 572         struct page *page;
 573         struct inode *btree_inode = root->fs_info->btree_inode;
 574         u64 start = 0;
 575         u64 end;
 576         unsigned long index;
 577
 578         while (1) {
 579                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 580                                             mark);
 581                 if (ret)
 582                         break;
 583
 584                 clear_extent_bits(dirty_pages, start, end, mark, GFP_NOFS);
 585                 while (start <= end) {
 586                         index = start >> PAGE_CACHE_SHIFT;
 587                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 588                         page = find_get_page(btree_inode->i_mapping, index);
 589                         if (!page)
 590                                 continue;
 591                         if (PageDirty(page)) {
 592                                 btree_lock_page_hook(page);
 593                                 wait_on_page_writeback(page);
 594                                 err = write_one_page(page, 0);
 595                                 if (err)
 596                                         werr = err;
 597                         }
 598                         wait_on_page_writeback(page);
 599                         page_cache_release(page);
 600                         cond_resched();
 601                 }
 602         }
 603         if (err)
 604                 werr = err;
 605         return werr;
 606 }
 607
 608 /*
 609  * when btree blocks are allocated, they have some corresponding bits set for
 610  * them in one of two extent_io trees.  This is used to make sure all of
 611  * those extents are on disk for transaction or log commit
 612  */
 613 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 614                                 struct extent_io_tree *dirty_pages, int mark)
 615 {
 616         int ret;
 617         int ret2;
 618
 619         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 620         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 621         return ret || ret2;
 622 }
 623
 624 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 625                                      struct btrfs_root *root)
 626 {
 627         if (!trans || !trans->transaction) {
 628                 struct inode *btree_inode;
 629                 btree_inode = root->fs_info->btree_inode;
 630                 return filemap_write_and_wait(btree_inode->i_mapping);
 631         }
 632         return btrfs_write_and_wait_marked_extents(root,
 633                                            &trans->transaction->dirty_pages,
 634                                            EXTENT_DIRTY);
 635 }
 636
 637 /*
 638  * this is used to update the root pointer in the tree of tree roots.
 639  *
 640  * But, in the case of the extent allocation tree, updating the root
 641  * pointer may allocate blocks which may change the root of the extent
 642  * allocation tree.
 643  *
 644  * So, this loops and repeats and makes sure the cowonly root didn't
 645  * change while the root pointer was being updated in the metadata.
 646  */
 647 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 648                                struct btrfs_root *root)
 649 {
 650         int ret;
 651         u64 old_root_bytenr;
 652         u64 old_root_used;
 653         struct btrfs_root *tree_root = root->fs_info->tree_root;
 654
 655         old_root_used = btrfs_root_used(&root->root_item);
 656         btrfs_write_dirty_block_groups(trans, root);
 657
 658         while (1) {
 659                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 660                 if (old_root_bytenr == root->node->start &&
 661                     old_root_used == btrfs_root_used(&root->root_item))
 662                         break;
 663
 664                 btrfs_set_root_node(&root->root_item, root->node);
 665                 ret = btrfs_update_root(trans, tree_root,
 666                                         &root->root_key,
 667                                         &root->root_item);
 668                 BUG_ON(ret);
 669
 670                 old_root_used = btrfs_root_used(&root->root_item);
 671                 ret = btrfs_write_dirty_block_groups(trans, root);
 672                 BUG_ON(ret);
 673         }
 674
 675         if (root != root->fs_info->extent_root)
 676                 switch_commit_root(root);
 677
 678         return 0;
 679 }
 680
 681 /*
 682  * update all the cowonly tree roots on disk
 683  */
 684 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 685                                          struct btrfs_root *root)
 686 {
 687         struct btrfs_fs_info *fs_info = root->fs_info;
 688         struct list_head *next;
 689         struct extent_buffer *eb;
 690         int ret;
 691
 692         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 693         BUG_ON(ret);
 694
 695         eb = btrfs_lock_root_node(fs_info->tree_root);
 696         btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
 697         btrfs_tree_unlock(eb);
 698         free_extent_buffer(eb);
 699
 700         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 701         BUG_ON(ret);
 702
 703         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 704                 next = fs_info->dirty_cowonly_roots.next;
 705                 list_del_init(next);
 706                 root = list_entry(next, struct btrfs_root, dirty_list);
 707
 708                 update_cowonly_root(trans, root);
 709         }
 710
 711         down_write(&fs_info->extent_commit_sem);
 712         switch_commit_root(fs_info->extent_root);
 713         up_write(&fs_info->extent_commit_sem);
 714
 715         return 0;
 716 }
 717
 718 /*
 719  * dead roots are old snapshots that need to be deleted.  This allocates
 720  * a dirty root struct and adds it into the list of dead roots that need to
 721  * be deleted
 722  */
 723 int btrfs_add_dead_root(struct btrfs_root *root)
 724 {
 725         mutex_lock(&root->fs_info->trans_mutex);
 726         list_add(&root->root_list, &root->fs_info->dead_roots);
 727         mutex_unlock(&root->fs_info->trans_mutex);
 728         return 0;
 729 }
 730
 731 /*
 732  * update all the cowonly tree roots on disk
 733  */
 734 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 735                                     struct btrfs_root *root)
 736 {
 737         struct btrfs_root *gang[8];
 738         struct btrfs_fs_info *fs_info = root->fs_info;
 739         int i;
 740         int ret;
 741         int err = 0;
 742
 743         while (1) {
 744                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
 745                                                  (void **)gang, 0,
 746                                                  ARRAY_SIZE(gang),
 747                                                  BTRFS_ROOT_TRANS_TAG);
 748                 if (ret == 0)
 749                         break;
 750                 for (i = 0; i < ret; i++) {
 751                         root = gang[i];
 752                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
 753                                         (unsigned long)root->root_key.objectid,
 754                                         BTRFS_ROOT_TRANS_TAG);
 755
 756                         btrfs_free_log(trans, root);
 757                         btrfs_update_reloc_root(trans, root);
 758                         btrfs_orphan_commit_root(trans, root);
 759
 760                         if (root->commit_root != root->node) {
 761                                 switch_commit_root(root);
 762                                 btrfs_set_root_node(&root->root_item,
 763                                                     root->node);
 764                         }
 765
 766                         err = btrfs_update_root(trans, fs_info->tree_root,
 767                                                 &root->root_key,
 768                                                 &root->root_item);
 769                         if (err)
 770                                 break;
 771                 }
 772         }
 773         return err;
 774 }
 775
 776 /*
 777  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
 778  * otherwise every leaf in the btree is read and defragged.
 779  */
 780 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 781 {
 782         struct btrfs_fs_info *info = root->fs_info;
 783         struct btrfs_trans_handle *trans;
 784         int ret;
 785         unsigned long nr;
 786
 787         if (xchg(&root->defrag_running, 1))
 788                 return 0;
 789
 790         while (1) {
 791                 trans = btrfs_start_transaction(root, 0);
 792                 if (IS_ERR(trans))
 793                         return PTR_ERR(trans);
 794
 795                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 796
 797                 nr = trans->blocks_used;
 798                 btrfs_end_transaction(trans, root);
 799                 btrfs_btree_balance_dirty(info->tree_root, nr);
 800                 cond_resched();
 801
 802                 if (root->fs_info->closing || ret != -EAGAIN)
 803                         break;
 804         }
 805         root->defrag_running = 0;
 806         return ret;
 807 }
 808
 809 #if 0
 810 /*
 811  * when dropping snapshots, we generate a ton of delayed refs, and it makes
 812  * sense not to join the transaction while it is trying to flush the current
 813  * queue of delayed refs out.
 814  *
 815  * This is used by the drop snapshot code only
 816  */
 817 static noinline int wait_transaction_pre_flush(struct btrfs_fs_info *info)
 818 {
 819         DEFINE_WAIT(wait);
 820
 821         mutex_lock(&info->trans_mutex);
 822         while (info->running_transaction &&
 823                info->running_transaction->delayed_refs.flushing) {
 824                 prepare_to_wait(&info->transaction_wait, &wait,
 825                                 TASK_UNINTERRUPTIBLE);
 826                 mutex_unlock(&info->trans_mutex);
 827
 828                 schedule();
 829
 830                 mutex_lock(&info->trans_mutex);
 831                 finish_wait(&info->transaction_wait, &wait);
 832         }
 833         mutex_unlock(&info->trans_mutex);
 834         return 0;
 835 }
 836
 837 /*
 838  * Given a list of roots that need to be deleted, call btrfs_drop_snapshot on
 839  * all of them
 840  */
 841 int btrfs_drop_dead_root(struct btrfs_root *root)
 842 {
 843         struct btrfs_trans_handle *trans;
 844         struct btrfs_root *tree_root = root->fs_info->tree_root;
 845         unsigned long nr;
 846         int ret;
 847
 848         while (1) {
 849                 /*
 850                  * we don't want to jump in and create a bunch of
 851                  * delayed refs if the transaction is starting to close
 852                  */
 853                 wait_transaction_pre_flush(tree_root->fs_info);
 854                 trans = btrfs_start_transaction(tree_root, 1);
 855
 856                 /*
 857                  * we've joined a transaction, make sure it isn't
 858                  * closing right now
 859                  */
 860                 if (trans->transaction->delayed_refs.flushing) {
 861                         btrfs_end_transaction(trans, tree_root);
 862                         continue;
 863                 }
 864
 865                 ret = btrfs_drop_snapshot(trans, root);
 866                 if (ret != -EAGAIN)
 867                         break;
 868
 869                 ret = btrfs_update_root(trans, tree_root,
 870                                         &root->root_key,
 871                                         &root->root_item);
 872                 if (ret)
 873                         break;
 874
 875                 nr = trans->blocks_used;
 876                 ret = btrfs_end_transaction(trans, tree_root);
 877                 BUG_ON(ret);
 878
 879                 btrfs_btree_balance_dirty(tree_root, nr);
 880                 cond_resched();
 881         }
 882         BUG_ON(ret);
 883
 884         ret = btrfs_del_root(trans, tree_root, &root->root_key);
 885         BUG_ON(ret);
 886
 887         nr = trans->blocks_used;
 888         ret = btrfs_end_transaction(trans, tree_root);
 889         BUG_ON(ret);
 890
 891         free_extent_buffer(root->node);
 892         free_extent_buffer(root->commit_root);
 893         kfree(root);
 894
 895         btrfs_btree_balance_dirty(tree_root, nr);
 896         return ret;
 897 }
 898 #endif
 899
 900 /*
 901  * new snapshots need to be created at a very specific time in the
 902  * transaction commit.  This does the actual creation
 903  */
 904 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 905                                    struct btrfs_fs_info *fs_info,
 906                                    struct btrfs_pending_snapshot *pending)
 907 {
 908         struct btrfs_key key;
 909         struct btrfs_root_item *new_root_item;
 910         struct btrfs_root *tree_root = fs_info->tree_root;
 911         struct btrfs_root *root = pending->root;
 912         struct btrfs_root *parent_root;
 913         struct inode *parent_inode;
 914         struct dentry *parent;
 915         struct dentry *dentry;
 916         struct extent_buffer *tmp;
 917         struct extent_buffer *old;
 918         int ret;
 919         u64 to_reserve = 0;
 920         u64 index = 0;
 921         u64 objectid;
 922         u64 root_flags;
 923
 924         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 925         if (!new_root_item) {
 926                 pending->error = -ENOMEM;
 927                 goto fail;
 928         }
 929
 930         ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
 931         if (ret) {
 932                 pending->error = ret;
 933                 goto fail;
 934         }
 935
 936         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
 937         btrfs_orphan_pre_snapshot(trans, pending, &to_reserve);
 938
 939         if (to_reserve > 0) {
 940                 ret = btrfs_block_rsv_add(trans, root, &pending->block_rsv,
 941                                           to_reserve);
 942                 if (ret) {
 943                         pending->error = ret;
 944                         goto fail;
 945                 }
 946         }
 947
 948         key.objectid = objectid;
 949         key.offset = (u64)-1;
 950         key.type = BTRFS_ROOT_ITEM_KEY;
 951
 952         trans->block_rsv = &pending->block_rsv;
 953
 954         dentry = pending->dentry;
 955         parent = dget_parent(dentry);
 956         parent_inode = parent->d_inode;
 957         parent_root = BTRFS_I(parent_inode)->root;
 958         record_root_in_trans(trans, parent_root);
 959
 960         /*
 961          * insert the directory item
 962          */
 963         ret = btrfs_set_inode_index(parent_inode, &index);
 964         BUG_ON(ret);
 965         ret = btrfs_insert_dir_item(trans, parent_root,
 966                                 dentry->d_name.name, dentry->d_name.len,
 967                                 parent_inode->i_ino, &key,
 968                                 BTRFS_FT_DIR, index);
 969         BUG_ON(ret);
 970
 971         btrfs_i_size_write(parent_inode, parent_inode->i_size +
 972                                          dentry->d_name.len * 2);
 973         ret = btrfs_update_inode(trans, parent_root, parent_inode);
 974         BUG_ON(ret);
 975
 976         record_root_in_trans(trans, root);
 977         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
 978         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
 979         btrfs_check_and_init_root_item(new_root_item);
 980
 981         root_flags = btrfs_root_flags(new_root_item);
 982         if (pending->readonly)
 983                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
 984         else
 985                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
 986         btrfs_set_root_flags(new_root_item, root_flags);
 987
 988         old = btrfs_lock_root_node(root);
 989         btrfs_cow_block(trans, root, old, NULL, 0, &old);
 990         btrfs_set_lock_blocking(old);
 991
 992         btrfs_copy_root(trans, root, old, &tmp, objectid);
 993         btrfs_tree_unlock(old);
 994         free_extent_buffer(old);
 995
 996         btrfs_set_root_node(new_root_item, tmp);
 997         /* record when the snapshot was created in key.offset */
 998         key.offset = trans->transid;
 999         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1000         btrfs_tree_unlock(tmp);
1001         free_extent_buffer(tmp);
1002         BUG_ON(ret);
1003
1004         /*
1005          * insert root back/forward references
1006          */
1007         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1008                                  parent_root->root_key.objectid,
1009                                  parent_inode->i_ino, index,
1010                                  dentry->d_name.name, dentry->d_name.len);
1011         BUG_ON(ret);
1012         dput(parent);
1013
1014         key.offset = (u64)-1;
1015         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1016         BUG_ON(IS_ERR(pending->snap));
1017
1018         btrfs_reloc_post_snapshot(trans, pending);
1019         btrfs_orphan_post_snapshot(trans, pending);
1020 fail:
1021         kfree(new_root_item);
1022         btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
1023         return 0;
1024 }
1025
1026 /*
1027  * create all the snapshots we've scheduled for creation
1028  */
1029 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1030                                              struct btrfs_fs_info *fs_info)
1031 {
1032         struct btrfs_pending_snapshot *pending;
1033         struct list_head *head = &trans->transaction->pending_snapshots;
1034         int ret;
1035
1036         list_for_each_entry(pending, head, list) {
1037                 ret = create_pending_snapshot(trans, fs_info, pending);
1038                 BUG_ON(ret);
1039         }
1040         return 0;
1041 }
1042
1043 static void update_super_roots(struct btrfs_root *root)
1044 {
1045         struct btrfs_root_item *root_item;
1046         struct btrfs_super_block *super;
1047
1048         super = &root->fs_info->super_copy;
1049
1050         root_item = &root->fs_info->chunk_root->root_item;
1051         super->chunk_root = root_item->bytenr;
1052         super->chunk_root_generation = root_item->generation;
1053         super->chunk_root_level = root_item->level;
1054
1055         root_item = &root->fs_info->tree_root->root_item;
1056         super->root = root_item->bytenr;
1057         super->generation = root_item->generation;
1058         super->root_level = root_item->level;
1059         if (super->cache_generation != 0 || btrfs_test_opt(root, SPACE_CACHE))
1060                 super->cache_generation = root_item->generation;
1061 }
1062
1063 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1064 {
1065         int ret = 0;
1066         spin_lock(&info->new_trans_lock);
1067         if (info->running_transaction)
1068                 ret = info->running_transaction->in_commit;
1069         spin_unlock(&info->new_trans_lock);
1070         return ret;
1071 }
1072
1073 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1074 {
1075         int ret = 0;
1076         spin_lock(&info->new_trans_lock);
1077         if (info->running_transaction)
1078                 ret = info->running_transaction->blocked;
1079         spin_unlock(&info->new_trans_lock);
1080         return ret;
1081 }
1082
1083 /*
1084  * wait for the current transaction commit to start and block subsequent
1085  * transaction joins
1086  */
1087 static void wait_current_trans_commit_start(struct btrfs_root *root,
1088                                             struct btrfs_transaction *trans)
1089 {
1090         DEFINE_WAIT(wait);
1091
1092         if (trans->in_commit)
1093                 return;
1094
1095         while (1) {
1096                 prepare_to_wait(&root->fs_info->transaction_blocked_wait, &wait,
1097                                 TASK_UNINTERRUPTIBLE);
1098                 if (trans->in_commit) {
1099                         finish_wait(&root->fs_info->transaction_blocked_wait,
1100                                     &wait);
1101                         break;
1102                 }
1103                 mutex_unlock(&root->fs_info->trans_mutex);
1104                 schedule();
1105                 mutex_lock(&root->fs_info->trans_mutex);
1106                 finish_wait(&root->fs_info->transaction_blocked_wait, &wait);
1107         }
1108 }
1109
1110 /*
1111  * wait for the current transaction to start and then become unblocked.
1112  * caller holds ref.
1113  */
1114 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1115                                          struct btrfs_transaction *trans)
1116 {
1117         DEFINE_WAIT(wait);
1118
1119         if (trans->commit_done || (trans->in_commit && !trans->blocked))
1120                 return;
1121
1122         while (1) {
1123                 prepare_to_wait(&root->fs_info->transaction_wait, &wait,
1124                                 TASK_UNINTERRUPTIBLE);
1125                 if (trans->commit_done ||
1126                     (trans->in_commit && !trans->blocked)) {
1127                         finish_wait(&root->fs_info->transaction_wait,
1128                                     &wait);
1129                         break;
1130                 }
1131                 mutex_unlock(&root->fs_info->trans_mutex);
1132                 schedule();
1133                 mutex_lock(&root->fs_info->trans_mutex);
1134                 finish_wait(&root->fs_info->transaction_wait,
1135                             &wait);
1136         }
1137 }
1138
1139 /*
1140  * commit transactions asynchronously. once btrfs_commit_transaction_async
1141  * returns, any subsequent transaction will not be allowed to join.
1142  */
1143 struct btrfs_async_commit {
1144         struct btrfs_trans_handle *newtrans;
1145         struct btrfs_root *root;
1146         struct delayed_work work;
1147 };
1148
1149 static void do_async_commit(struct work_struct *work)
1150 {
1151         struct btrfs_async_commit *ac =
1152                 container_of(work, struct btrfs_async_commit, work.work);
1153
1154         btrfs_commit_transaction(ac->newtrans, ac->root);
1155         kfree(ac);
1156 }
1157
1158 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1159                                    struct btrfs_root *root,
1160                                    int wait_for_unblock)
1161 {
1162         struct btrfs_async_commit *ac;
1163         struct btrfs_transaction *cur_trans;
1164
1165         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1166         if (!ac)
1167                 return -ENOMEM;
1168
1169         INIT_DELAYED_WORK(&ac->work, do_async_commit);
1170         ac->root = root;
1171         ac->newtrans = btrfs_join_transaction(root, 0);
1172         if (IS_ERR(ac->newtrans)) {
1173                 int err = PTR_ERR(ac->newtrans);
1174                 kfree(ac);
1175                 return err;
1176         }
1177
1178         /* take transaction reference */
1179         mutex_lock(&root->fs_info->trans_mutex);
1180         cur_trans = trans->transaction;
1181         cur_trans->use_count++;
1182         mutex_unlock(&root->fs_info->trans_mutex);
1183
1184         btrfs_end_transaction(trans, root);
1185         schedule_delayed_work(&ac->work, 0);
1186
1187         /* wait for transaction to start and unblock */
1188         mutex_lock(&root->fs_info->trans_mutex);
1189         if (wait_for_unblock)
1190                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1191         else
1192                 wait_current_trans_commit_start(root, cur_trans);
1193         put_transaction(cur_trans);
1194         mutex_unlock(&root->fs_info->trans_mutex);
1195
1196         return 0;
1197 }
1198
1199 /*
1200  * btrfs_transaction state sequence:
1201  *    in_commit = 0, blocked = 0  (initial)
1202  *    in_commit = 1, blocked = 1
1203  *    blocked = 0
1204  *    commit_done = 1
1205  */
1206 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1207                              struct btrfs_root *root)
1208 {
1209         unsigned long joined = 0;
1210         struct btrfs_transaction *cur_trans;
1211         struct btrfs_transaction *prev_trans = NULL;
1212         DEFINE_WAIT(wait);
1213         int ret;
1214         int should_grow = 0;
1215         unsigned long now = get_seconds();
1216         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1217
1218         btrfs_run_ordered_operations(root, 0);
1219
1220         /* make a pass through all the delayed refs we have so far
1221          * any runnings procs may add more while we are here
1222          */
1223         ret = btrfs_run_delayed_refs(trans, root, 0);
1224         BUG_ON(ret);
1225
1226         btrfs_trans_release_metadata(trans, root);
1227
1228         cur_trans = trans->transaction;
1229         /*
1230          * set the flushing flag so procs in this transaction have to
1231          * start sending their work down.
1232          */
1233         cur_trans->delayed_refs.flushing = 1;
1234
1235         ret = btrfs_run_delayed_refs(trans, root, 0);
1236         BUG_ON(ret);
1237
1238         mutex_lock(&root->fs_info->trans_mutex);
1239         if (cur_trans->in_commit) {
1240                 cur_trans->use_count++;
1241                 mutex_unlock(&root->fs_info->trans_mutex);
1242                 btrfs_end_transaction(trans, root);
1243
1244                 ret = wait_for_commit(root, cur_trans);
1245                 BUG_ON(ret);
1246
1247                 mutex_lock(&root->fs_info->trans_mutex);
1248                 put_transaction(cur_trans);
1249                 mutex_unlock(&root->fs_info->trans_mutex);
1250
1251                 return 0;
1252         }
1253
1254         trans->transaction->in_commit = 1;
1255         trans->transaction->blocked = 1;
1256         wake_up(&root->fs_info->transaction_blocked_wait);
1257
1258         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1259                 prev_trans = list_entry(cur_trans->list.prev,
1260                                         struct btrfs_transaction, list);
1261                 if (!prev_trans->commit_done) {
1262                         prev_trans->use_count++;
1263                         mutex_unlock(&root->fs_info->trans_mutex);
1264
1265                         wait_for_commit(root, prev_trans);
1266
1267                         mutex_lock(&root->fs_info->trans_mutex);
1268                         put_transaction(prev_trans);
1269                 }
1270         }
1271
1272         if (now < cur_trans->start_time || now - cur_trans->start_time < 1)
1273                 should_grow = 1;
1274
1275         do {
1276                 int snap_pending = 0;
1277                 joined = cur_trans->num_joined;
1278                 if (!list_empty(&trans->transaction->pending_snapshots))
1279                         snap_pending = 1;
1280
1281                 WARN_ON(cur_trans != trans->transaction);
1282                 mutex_unlock(&root->fs_info->trans_mutex);
1283
1284                 if (flush_on_commit || snap_pending) {
1285                         btrfs_start_delalloc_inodes(root, 1);
1286                         ret = btrfs_wait_ordered_extents(root, 0, 1);
1287                         BUG_ON(ret);
1288                 }
1289
1290                 /*
1291                  * rename don't use btrfs_join_transaction, so, once we
1292                  * set the transaction to blocked above, we aren't going
1293                  * to get any new ordered operations.  We can safely run
1294                  * it here and no for sure that nothing new will be added
1295                  * to the list
1296                  */
1297                 btrfs_run_ordered_operations(root, 1);
1298
1299                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1300                                 TASK_UNINTERRUPTIBLE);
1301
1302                 smp_mb();
1303                 if (cur_trans->num_writers > 1)
1304                         schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1305                 else if (should_grow)
1306                         schedule_timeout(1);
1307
1308                 mutex_lock(&root->fs_info->trans_mutex);
1309                 finish_wait(&cur_trans->writer_wait, &wait);
1310         } while (cur_trans->num_writers > 1 ||
1311                  (should_grow && cur_trans->num_joined != joined));
1312
1313         ret = create_pending_snapshots(trans, root->fs_info);
1314         BUG_ON(ret);
1315
1316         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1317         BUG_ON(ret);
1318
1319         WARN_ON(cur_trans != trans->transaction);
1320
1321         /* btrfs_commit_tree_roots is responsible for getting the
1322          * various roots consistent with each other.  Every pointer
1323          * in the tree of tree roots has to point to the most up to date
1324          * root for every subvolume and other tree.  So, we have to keep
1325          * the tree logging code from jumping in and changing any
1326          * of the trees.
1327          *
1328          * At this point in the commit, there can't be any tree-log
1329          * writers, but a little lower down we drop the trans mutex
1330          * and let new people in.  By holding the tree_log_mutex
1331          * from now until after the super is written, we avoid races
1332          * with the tree-log code.
1333          */
1334         mutex_lock(&root->fs_info->tree_log_mutex);
1335
1336         ret = commit_fs_roots(trans, root);
1337         BUG_ON(ret);
1338
1339         /* commit_fs_roots gets rid of all the tree log roots, it is now
1340          * safe to free the root of tree log roots
1341          */
1342         btrfs_free_log_root_tree(trans, root->fs_info);
1343
1344         ret = commit_cowonly_roots(trans, root);
1345         BUG_ON(ret);
1346
1347         btrfs_prepare_extent_commit(trans, root);
1348
1349         cur_trans = root->fs_info->running_transaction;
1350         spin_lock(&root->fs_info->new_trans_lock);
1351         root->fs_info->running_transaction = NULL;
1352         spin_unlock(&root->fs_info->new_trans_lock);
1353
1354         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1355                             root->fs_info->tree_root->node);
1356         switch_commit_root(root->fs_info->tree_root);
1357
1358         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1359                             root->fs_info->chunk_root->node);
1360         switch_commit_root(root->fs_info->chunk_root);
1361
1362         update_super_roots(root);
1363
1364         if (!root->fs_info->log_root_recovering) {
1365                 btrfs_set_super_log_root(&root->fs_info->super_copy, 0);
1366                 btrfs_set_super_log_root_level(&root->fs_info->super_copy, 0);
1367         }
1368
1369         memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
1370                sizeof(root->fs_info->super_copy));
1371
1372         trans->transaction->blocked = 0;
1373
1374         wake_up(&root->fs_info->transaction_wait);
1375
1376         mutex_unlock(&root->fs_info->trans_mutex);
1377         ret = btrfs_write_and_wait_transaction(trans, root);
1378         BUG_ON(ret);
1379         write_ctree_super(trans, root, 0);
1380
1381         /*
1382          * the super is written, we can safely allow the tree-loggers
1383          * to go about their business
1384          */
1385         mutex_unlock(&root->fs_info->tree_log_mutex);
1386
1387         btrfs_finish_extent_commit(trans, root);
1388
1389         mutex_lock(&root->fs_info->trans_mutex);
1390
1391         cur_trans->commit_done = 1;
1392
1393         root->fs_info->last_trans_committed = cur_trans->transid;
1394
1395         wake_up(&cur_trans->commit_wait);
1396
1397         put_transaction(cur_trans);
1398         put_transaction(cur_trans);
1399
1400         trace_btrfs_transaction_commit(root);
1401
1402         mutex_unlock(&root->fs_info->trans_mutex);
1403
1404         if (current->journal_info == trans)
1405                 current->journal_info = NULL;
1406
1407         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1408
1409         if (current != root->fs_info->transaction_kthread)
1410                 btrfs_run_delayed_iputs(root);
1411
1412         return ret;
1413 }
1414
1415 /*
1416  * interface function to delete all the snapshots we have scheduled for deletion
1417  */
1418 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1419 {
1420         LIST_HEAD(list);
1421         struct btrfs_fs_info *fs_info = root->fs_info;
1422
1423         mutex_lock(&fs_info->trans_mutex);
1424         list_splice_init(&fs_info->dead_roots, &list);
1425         mutex_unlock(&fs_info->trans_mutex);
1426
1427         while (!list_empty(&list)) {
1428                 root = list_entry(list.next, struct btrfs_root, root_list);
1429                 list_del(&root->root_list);
1430
1431                 if (btrfs_header_backref_rev(root->node) <
1432                     BTRFS_MIXED_BACKREF_REV)
1433                         btrfs_drop_snapshot(root, NULL, 0);
1434                 else
1435                         btrfs_drop_snapshot(root, NULL, 1);
1436         }
1437         return 0;
1438 }