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   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/sched.h>
  21 #include "ctree.h"
  22 #include "disk-io.h"
  23 #include "transaction.h"
  24
  25 static int total_trans = 0;
  26 extern struct kmem_cache *btrfs_trans_handle_cachep;
  27 extern struct kmem_cache *btrfs_transaction_cachep;
  28
  29 static struct workqueue_struct *trans_wq;
  30
  31 #define BTRFS_ROOT_TRANS_TAG 0
  32 #define BTRFS_ROOT_DEFRAG_TAG 1
  33
  34 static void put_transaction(struct btrfs_transaction *transaction)
  35 {
  36         WARN_ON(transaction->use_count == 0);
  37         transaction->use_count--;
  38         if (transaction->use_count == 0) {
  39                 WARN_ON(total_trans == 0);
  40                 total_trans--;
  41                 list_del_init(&transaction->list);
  42                 memset(transaction, 0, sizeof(*transaction));
  43                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  44         }
  45 }
  46
  47 static int join_transaction(struct btrfs_root *root)
  48 {
  49         struct btrfs_transaction *cur_trans;
  50         cur_trans = root->fs_info->running_transaction;
  51         if (!cur_trans) {
  52                 cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
  53                                              GFP_NOFS);
  54                 total_trans++;
  55                 BUG_ON(!cur_trans);
  56                 root->fs_info->generation++;
  57                 root->fs_info->running_transaction = cur_trans;
  58                 cur_trans->num_writers = 1;
  59                 cur_trans->num_joined = 0;
  60                 cur_trans->transid = root->fs_info->generation;
  61                 init_waitqueue_head(&cur_trans->writer_wait);
  62                 init_waitqueue_head(&cur_trans->commit_wait);
  63                 cur_trans->in_commit = 0;
  64                 cur_trans->use_count = 1;
  65                 cur_trans->commit_done = 0;
  66                 cur_trans->start_time = get_seconds();
  67                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
  68                 init_bit_radix(&cur_trans->dirty_pages);
  69         } else {
  70                 cur_trans->num_writers++;
  71                 cur_trans->num_joined++;
  72         }
  73
  74         return 0;
  75 }
  76
  77 static int record_root_in_trans(struct btrfs_root *root)
  78 {
  79         u64 running_trans_id = root->fs_info->running_transaction->transid;
  80         if (root->ref_cows && root->last_trans < running_trans_id) {
  81                 WARN_ON(root == root->fs_info->extent_root);
  82                 if (root->root_item.refs != 0) {
  83                         radix_tree_tag_set(&root->fs_info->fs_roots_radix,
  84                                    (unsigned long)root->root_key.objectid,
  85                                    BTRFS_ROOT_TRANS_TAG);
  86                         radix_tree_tag_set(&root->fs_info->fs_roots_radix,
  87                                    (unsigned long)root->root_key.objectid,
  88                                    BTRFS_ROOT_DEFRAG_TAG);
  89                         root->commit_root = root->node;
  90                         get_bh(root->node);
  91                 } else {
  92                         WARN_ON(1);
  93                 }
  94                 root->last_trans = running_trans_id;
  95         }
  96         return 0;
  97 }
  98
  99 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 100                                                    int num_blocks)
 101 {
 102         struct btrfs_trans_handle *h =
 103                 kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 104         int ret;
 105
 106         mutex_lock(&root->fs_info->trans_mutex);
 107         ret = join_transaction(root);
 108         BUG_ON(ret);
 109
 110         record_root_in_trans(root);
 111         h->transid = root->fs_info->running_transaction->transid;
 112         h->transaction = root->fs_info->running_transaction;
 113         h->blocks_reserved = num_blocks;
 114         h->blocks_used = 0;
 115         h->block_group = NULL;
 116         h->alloc_exclude_nr = 0;
 117         h->alloc_exclude_start = 0;
 118         root->fs_info->running_transaction->use_count++;
 119         mutex_unlock(&root->fs_info->trans_mutex);
 120         return h;
 121 }
 122
 123 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 124                           struct btrfs_root *root)
 125 {
 126         struct btrfs_transaction *cur_trans;
 127
 128         mutex_lock(&root->fs_info->trans_mutex);
 129         cur_trans = root->fs_info->running_transaction;
 130         WARN_ON(cur_trans != trans->transaction);
 131         WARN_ON(cur_trans->num_writers < 1);
 132         cur_trans->num_writers--;
 133         if (waitqueue_active(&cur_trans->writer_wait))
 134                 wake_up(&cur_trans->writer_wait);
 135         put_transaction(cur_trans);
 136         mutex_unlock(&root->fs_info->trans_mutex);
 137         memset(trans, 0, sizeof(*trans));
 138         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 139         return 0;
 140 }
 141
 142
 143 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 144                                      struct btrfs_root *root)
 145 {
 146         unsigned long gang[16];
 147         int ret;
 148         int i;
 149         int err;
 150         int werr = 0;
 151         struct page *page;
 152         struct radix_tree_root *dirty_pages;
 153         struct inode *btree_inode = root->fs_info->btree_inode;
 154
 155         if (!trans || !trans->transaction) {
 156                 return filemap_write_and_wait(btree_inode->i_mapping);
 157         }
 158         dirty_pages = &trans->transaction->dirty_pages;
 159         while(1) {
 160                 ret = find_first_radix_bit(dirty_pages, gang,
 161                                            0, ARRAY_SIZE(gang));
 162                 if (!ret)
 163                         break;
 164                 for (i = 0; i < ret; i++) {
 165                         /* FIXME EIO */
 166                         clear_radix_bit(dirty_pages, gang[i]);
 167                         page = find_lock_page(btree_inode->i_mapping,
 168                                               gang[i]);
 169                         if (!page)
 170                                 continue;
 171                         if (PageWriteback(page)) {
 172                                 if (PageDirty(page))
 173                                         wait_on_page_writeback(page);
 174                                 else {
 175                                         unlock_page(page);
 176                                         page_cache_release(page);
 177                                         continue;
 178                                 }
 179                         }
 180                         err = write_one_page(page, 0);
 181                         if (err)
 182                                 werr = err;
 183                         page_cache_release(page);
 184                 }
 185         }
 186         err = filemap_fdatawait(btree_inode->i_mapping);
 187         if (err)
 188                 werr = err;
 189         return werr;
 190 }
 191
 192 int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
 193                             struct btrfs_root *root)
 194 {
 195         int ret;
 196         u64 old_extent_block;
 197         struct btrfs_fs_info *fs_info = root->fs_info;
 198         struct btrfs_root *tree_root = fs_info->tree_root;
 199         struct btrfs_root *extent_root = fs_info->extent_root;
 200
 201         btrfs_write_dirty_block_groups(trans, extent_root);
 202         while(1) {
 203                 old_extent_block = btrfs_root_blocknr(&extent_root->root_item);
 204                 if (old_extent_block == bh_blocknr(extent_root->node))
 205                         break;
 206                 btrfs_set_root_blocknr(&extent_root->root_item,
 207                                        bh_blocknr(extent_root->node));
 208                 ret = btrfs_update_root(trans, tree_root,
 209                                         &extent_root->root_key,
 210                                         &extent_root->root_item);
 211                 BUG_ON(ret);
 212                 btrfs_write_dirty_block_groups(trans, extent_root);
 213         }
 214         return 0;
 215 }
 216
 217 static int wait_for_commit(struct btrfs_root *root,
 218                            struct btrfs_transaction *commit)
 219 {
 220         DEFINE_WAIT(wait);
 221         mutex_lock(&root->fs_info->trans_mutex);
 222         while(!commit->commit_done) {
 223                 prepare_to_wait(&commit->commit_wait, &wait,
 224                                 TASK_UNINTERRUPTIBLE);
 225                 if (commit->commit_done)
 226                         break;
 227                 mutex_unlock(&root->fs_info->trans_mutex);
 228                 schedule();
 229                 mutex_lock(&root->fs_info->trans_mutex);
 230         }
 231         mutex_unlock(&root->fs_info->trans_mutex);
 232         finish_wait(&commit->commit_wait, &wait);
 233         return 0;
 234 }
 235
 236 struct dirty_root {
 237         struct list_head list;
 238         struct btrfs_root *root;
 239         struct btrfs_root *latest_root;
 240 };
 241
 242 int btrfs_add_dead_root(struct btrfs_root *root,
 243                         struct btrfs_root *latest,
 244                         struct list_head *dead_list)
 245 {
 246         struct dirty_root *dirty;
 247
 248         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 249         if (!dirty)
 250                 return -ENOMEM;
 251         dirty->root = root;
 252         dirty->latest_root = latest;
 253         list_add(&dirty->list, dead_list);
 254         return 0;
 255 }
 256
 257 static int add_dirty_roots(struct btrfs_trans_handle *trans,
 258                            struct radix_tree_root *radix,
 259                            struct list_head *list)
 260 {
 261         struct dirty_root *dirty;
 262         struct btrfs_root *gang[8];
 263         struct btrfs_root *root;
 264         int i;
 265         int ret;
 266         int err = 0;
 267         u32 refs;
 268
 269         while(1) {
 270                 ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
 271                                                  ARRAY_SIZE(gang),
 272                                                  BTRFS_ROOT_TRANS_TAG);
 273                 if (ret == 0)
 274                         break;
 275                 for (i = 0; i < ret; i++) {
 276                         root = gang[i];
 277                         radix_tree_tag_clear(radix,
 278                                      (unsigned long)root->root_key.objectid,
 279                                      BTRFS_ROOT_TRANS_TAG);
 280                         if (root->commit_root == root->node) {
 281                                 WARN_ON(bh_blocknr(root->node) !=
 282                                         btrfs_root_blocknr(&root->root_item));
 283                                 brelse(root->commit_root);
 284                                 root->commit_root = NULL;
 285
 286                                 /* make sure to update the root on disk
 287                                  * so we get any updates to the block used
 288                                  * counts
 289                                  */
 290                                 err = btrfs_update_root(trans,
 291                                                 root->fs_info->tree_root,
 292                                                 &root->root_key,
 293                                                 &root->root_item);
 294                                 continue;
 295                         }
 296                         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 297                         BUG_ON(!dirty);
 298                         dirty->root = kmalloc(sizeof(*dirty->root), GFP_NOFS);
 299                         BUG_ON(!dirty->root);
 300
 301                         memset(&root->root_item.drop_progress, 0,
 302                                sizeof(struct btrfs_disk_key));
 303                         root->root_item.drop_level = 0;
 304
 305                         memcpy(dirty->root, root, sizeof(*root));
 306                         dirty->root->node = root->commit_root;
 307                         dirty->latest_root = root;
 308                         root->commit_root = NULL;
 309
 310                         root->root_key.offset = root->fs_info->generation;
 311                         btrfs_set_root_blocknr(&root->root_item,
 312                                                bh_blocknr(root->node));
 313                         err = btrfs_insert_root(trans, root->fs_info->tree_root,
 314                                                 &root->root_key,
 315                                                 &root->root_item);
 316                         if (err)
 317                                 break;
 318
 319                         refs = btrfs_root_refs(&dirty->root->root_item);
 320                         btrfs_set_root_refs(&dirty->root->root_item, refs - 1);
 321                         err = btrfs_update_root(trans, root->fs_info->tree_root,
 322                                                 &dirty->root->root_key,
 323                                                 &dirty->root->root_item);
 324
 325                         BUG_ON(err);
 326                         if (refs == 1) {
 327                                 list_add(&dirty->list, list);
 328                         } else {
 329                                 WARN_ON(1);
 330                                 kfree(dirty->root);
 331                                 kfree(dirty);
 332                         }
 333                 }
 334         }
 335         return err;
 336 }
 337
 338 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 339 {
 340         struct btrfs_fs_info *info = root->fs_info;
 341         int ret;
 342         struct btrfs_trans_handle *trans;
 343
 344         if (root->defrag_running)
 345                 return 0;
 346
 347         trans = btrfs_start_transaction(root, 1);
 348         while (1) {
 349                 root->defrag_running = 1;
 350                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 351                 btrfs_end_transaction(trans, root);
 352                 mutex_unlock(&info->fs_mutex);
 353
 354                 btrfs_btree_balance_dirty(root);
 355                 cond_resched();
 356
 357                 mutex_lock(&info->fs_mutex);
 358                 trans = btrfs_start_transaction(root, 1);
 359                 if (ret != -EAGAIN)
 360                         break;
 361         }
 362         root->defrag_running = 0;
 363         radix_tree_tag_clear(&info->fs_roots_radix,
 364                      (unsigned long)root->root_key.objectid,
 365                      BTRFS_ROOT_DEFRAG_TAG);
 366         btrfs_end_transaction(trans, root);
 367         return 0;
 368 }
 369
 370 int btrfs_defrag_dirty_roots(struct btrfs_fs_info *info)
 371 {
 372         struct btrfs_root *gang[1];
 373         struct btrfs_root *root;
 374         int i;
 375         int ret;
 376         int err = 0;
 377         u64 last = 0;
 378
 379         while(1) {
 380                 ret = radix_tree_gang_lookup_tag(&info->fs_roots_radix,
 381                                                  (void **)gang, last,
 382                                                  ARRAY_SIZE(gang),
 383                                                  BTRFS_ROOT_DEFRAG_TAG);
 384                 if (ret == 0)
 385                         break;
 386                 for (i = 0; i < ret; i++) {
 387                         root = gang[i];
 388                         last = root->root_key.objectid + 1;
 389                         btrfs_defrag_root(root, 1);
 390                 }
 391         }
 392         btrfs_defrag_root(info->extent_root, 1);
 393         return err;
 394 }
 395
 396 static int drop_dirty_roots(struct btrfs_root *tree_root,
 397                             struct list_head *list)
 398 {
 399         struct dirty_root *dirty;
 400         struct btrfs_trans_handle *trans;
 401         u64 num_blocks;
 402         u64 blocks_used;
 403         int ret = 0;
 404         int err;
 405
 406         while(!list_empty(list)) {
 407                 struct btrfs_root *root;
 408
 409                 mutex_lock(&tree_root->fs_info->fs_mutex);
 410                 dirty = list_entry(list->next, struct dirty_root, list);
 411                 list_del_init(&dirty->list);
 412
 413                 num_blocks = btrfs_root_blocks_used(&dirty->root->root_item);
 414                 root = dirty->latest_root;
 415
 416                 while(1) {
 417                         trans = btrfs_start_transaction(tree_root, 1);
 418                         ret = btrfs_drop_snapshot(trans, dirty->root);
 419                         if (ret != -EAGAIN) {
 420                                 break;
 421                         }
 422
 423                         err = btrfs_update_root(trans,
 424                                         tree_root,
 425                                         &dirty->root->root_key,
 426                                         &dirty->root->root_item);
 427                         if (err)
 428                                 ret = err;
 429                         ret = btrfs_end_transaction(trans, tree_root);
 430                         BUG_ON(ret);
 431                         mutex_unlock(&tree_root->fs_info->fs_mutex);
 432
 433                         btrfs_btree_balance_dirty(tree_root);
 434                         schedule();
 435
 436                         mutex_lock(&tree_root->fs_info->fs_mutex);
 437                 }
 438                 BUG_ON(ret);
 439
 440                 num_blocks -= btrfs_root_blocks_used(&dirty->root->root_item);
 441                 blocks_used = btrfs_root_blocks_used(&root->root_item);
 442                 if (num_blocks) {
 443                         record_root_in_trans(root);
 444                         btrfs_set_root_blocks_used(&root->root_item,
 445                                                    blocks_used - num_blocks);
 446                 }
 447                 ret = btrfs_del_root(trans, tree_root, &dirty->root->root_key);
 448                 if (ret) {
 449                         BUG();
 450                         break;
 451                 }
 452                 ret = btrfs_end_transaction(trans, tree_root);
 453                 BUG_ON(ret);
 454
 455                 kfree(dirty->root);
 456                 kfree(dirty);
 457                 mutex_unlock(&tree_root->fs_info->fs_mutex);
 458                 btrfs_btree_balance_dirty(tree_root);
 459                 schedule();
 460         }
 461         return ret;
 462 }
 463
 464 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 465                              struct btrfs_root *root)
 466 {
 467         unsigned long joined = 0;
 468         unsigned long timeout = 1;
 469         struct btrfs_transaction *cur_trans;
 470         struct btrfs_transaction *prev_trans = NULL;
 471         struct list_head dirty_fs_roots;
 472         struct radix_tree_root pinned_copy;
 473         DEFINE_WAIT(wait);
 474         int ret;
 475
 476         init_bit_radix(&pinned_copy);
 477         INIT_LIST_HEAD(&dirty_fs_roots);
 478
 479         mutex_lock(&root->fs_info->trans_mutex);
 480         if (trans->transaction->in_commit) {
 481                 cur_trans = trans->transaction;
 482                 trans->transaction->use_count++;
 483                 mutex_unlock(&root->fs_info->trans_mutex);
 484                 btrfs_end_transaction(trans, root);
 485
 486                 mutex_unlock(&root->fs_info->fs_mutex);
 487                 ret = wait_for_commit(root, cur_trans);
 488                 BUG_ON(ret);
 489
 490                 mutex_lock(&root->fs_info->trans_mutex);
 491                 put_transaction(cur_trans);
 492                 mutex_unlock(&root->fs_info->trans_mutex);
 493
 494                 mutex_lock(&root->fs_info->fs_mutex);
 495                 return 0;
 496         }
 497         trans->transaction->in_commit = 1;
 498         cur_trans = trans->transaction;
 499         if (cur_trans->list.prev != &root->fs_info->trans_list) {
 500                 prev_trans = list_entry(cur_trans->list.prev,
 501                                         struct btrfs_transaction, list);
 502                 if (!prev_trans->commit_done) {
 503                         prev_trans->use_count++;
 504                         mutex_unlock(&root->fs_info->fs_mutex);
 505                         mutex_unlock(&root->fs_info->trans_mutex);
 506
 507                         wait_for_commit(root, prev_trans);
 508
 509                         mutex_lock(&root->fs_info->fs_mutex);
 510                         mutex_lock(&root->fs_info->trans_mutex);
 511                         put_transaction(prev_trans);
 512                 }
 513         }
 514
 515         do {
 516                 joined = cur_trans->num_joined;
 517                 WARN_ON(cur_trans != trans->transaction);
 518                 prepare_to_wait(&cur_trans->writer_wait, &wait,
 519                                 TASK_UNINTERRUPTIBLE);
 520
 521                 if (cur_trans->num_writers > 1)
 522                         timeout = MAX_SCHEDULE_TIMEOUT;
 523                 else
 524                         timeout = 1;
 525
 526                 mutex_unlock(&root->fs_info->fs_mutex);
 527                 mutex_unlock(&root->fs_info->trans_mutex);
 528
 529                 schedule_timeout(timeout);
 530
 531                 mutex_lock(&root->fs_info->fs_mutex);
 532                 mutex_lock(&root->fs_info->trans_mutex);
 533                 finish_wait(&cur_trans->writer_wait, &wait);
 534         } while (cur_trans->num_writers > 1 ||
 535                  (cur_trans->num_joined != joined));
 536
 537         WARN_ON(cur_trans != trans->transaction);
 538         ret = add_dirty_roots(trans, &root->fs_info->fs_roots_radix,
 539                               &dirty_fs_roots);
 540         BUG_ON(ret);
 541
 542         ret = btrfs_commit_tree_roots(trans, root);
 543         BUG_ON(ret);
 544
 545         cur_trans = root->fs_info->running_transaction;
 546         root->fs_info->running_transaction = NULL;
 547         btrfs_set_super_generation(&root->fs_info->super_copy,
 548                                    cur_trans->transid);
 549         btrfs_set_super_root(&root->fs_info->super_copy,
 550                              bh_blocknr(root->fs_info->tree_root->node));
 551         memcpy(root->fs_info->disk_super, &root->fs_info->super_copy,
 552                sizeof(root->fs_info->super_copy));
 553
 554         btrfs_copy_pinned(root, &pinned_copy);
 555
 556         mutex_unlock(&root->fs_info->trans_mutex);
 557         mutex_unlock(&root->fs_info->fs_mutex);
 558         ret = btrfs_write_and_wait_transaction(trans, root);
 559         BUG_ON(ret);
 560         write_ctree_super(trans, root);
 561         mutex_lock(&root->fs_info->fs_mutex);
 562         btrfs_finish_extent_commit(trans, root, &pinned_copy);
 563         mutex_lock(&root->fs_info->trans_mutex);
 564         cur_trans->commit_done = 1;
 565         root->fs_info->last_trans_committed = cur_trans->transid;
 566         wake_up(&cur_trans->commit_wait);
 567         put_transaction(cur_trans);
 568         put_transaction(cur_trans);
 569
 570         if (root->fs_info->closing)
 571                 list_splice_init(&root->fs_info->dead_roots, &dirty_fs_roots);
 572         else
 573                 list_splice_init(&dirty_fs_roots, &root->fs_info->dead_roots);
 574
 575         mutex_unlock(&root->fs_info->trans_mutex);
 576         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 577
 578         if (root->fs_info->closing) {
 579                 mutex_unlock(&root->fs_info->fs_mutex);
 580                 drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
 581                 mutex_lock(&root->fs_info->fs_mutex);
 582         }
 583         return ret;
 584 }
 585
 586 int btrfs_clean_old_snapshots(struct btrfs_root *root)
 587 {
 588         struct list_head dirty_roots;
 589         INIT_LIST_HEAD(&dirty_roots);
 590
 591         mutex_lock(&root->fs_info->trans_mutex);
 592         list_splice_init(&root->fs_info->dead_roots, &dirty_roots);
 593         mutex_unlock(&root->fs_info->trans_mutex);
 594
 595         if (!list_empty(&dirty_roots)) {
 596                 drop_dirty_roots(root, &dirty_roots);
 597         }
 598         return 0;
 599 }
 600 void btrfs_transaction_cleaner(struct work_struct *work)
 601 {
 602         struct btrfs_fs_info *fs_info = container_of(work,
 603                                                      struct btrfs_fs_info,
 604                                                      trans_work.work);
 605
 606         struct btrfs_root *root = fs_info->tree_root;
 607         struct btrfs_transaction *cur;
 608         struct btrfs_trans_handle *trans;
 609         unsigned long now;
 610         unsigned long delay = HZ * 30;
 611         int ret;
 612
 613         mutex_lock(&root->fs_info->fs_mutex);
 614         mutex_lock(&root->fs_info->trans_mutex);
 615         cur = root->fs_info->running_transaction;
 616         if (!cur) {
 617                 mutex_unlock(&root->fs_info->trans_mutex);
 618                 goto out;
 619         }
 620         now = get_seconds();
 621         if (now < cur->start_time || now - cur->start_time < 30) {
 622                 mutex_unlock(&root->fs_info->trans_mutex);
 623                 delay = HZ * 5;
 624                 goto out;
 625         }
 626         mutex_unlock(&root->fs_info->trans_mutex);
 627         btrfs_defrag_dirty_roots(root->fs_info);
 628         trans = btrfs_start_transaction(root, 1);
 629         ret = btrfs_commit_transaction(trans, root);
 630 out:
 631         mutex_unlock(&root->fs_info->fs_mutex);
 632         btrfs_clean_old_snapshots(root);
 633         btrfs_transaction_queue_work(root, delay);
 634 }
 635
 636 void btrfs_transaction_queue_work(struct btrfs_root *root, int delay)
 637 {
 638         queue_delayed_work(trans_wq, &root->fs_info->trans_work, delay);
 639 }
 640
 641 void btrfs_transaction_flush_work(struct btrfs_root *root)
 642 {
 643         cancel_rearming_delayed_workqueue(trans_wq, &root->fs_info->trans_work);
 644         flush_workqueue(trans_wq);
 645 }
 646
 647 void __init btrfs_init_transaction_sys(void)
 648 {
 649         trans_wq = create_workqueue("btrfs");
 650 }
 651
 652 void __exit btrfs_exit_transaction_sys(void)
 653 {
 654         destroy_workqueue(trans_wq);
 655 }
 656