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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, struct list_head *dead_list)
 243 {
 244         struct dirty_root *dirty;
 245
 246         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 247         if (!dirty)
 248                 return -ENOMEM;
 249         dirty->root = root;
 250         list_add(&dirty->list, dead_list);
 251         return 0;
 252 }
 253
 254 static int add_dirty_roots(struct btrfs_trans_handle *trans,
 255                            struct radix_tree_root *radix,
 256                            struct list_head *list)
 257 {
 258         struct dirty_root *dirty;
 259         struct btrfs_root *gang[8];
 260         struct btrfs_root *root;
 261         int i;
 262         int ret;
 263         int err = 0;
 264         u32 refs;
 265
 266         while(1) {
 267                 ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
 268                                                  ARRAY_SIZE(gang),
 269                                                  BTRFS_ROOT_TRANS_TAG);
 270                 if (ret == 0)
 271                         break;
 272                 for (i = 0; i < ret; i++) {
 273                         root = gang[i];
 274                         radix_tree_tag_clear(radix,
 275                                      (unsigned long)root->root_key.objectid,
 276                                      BTRFS_ROOT_TRANS_TAG);
 277                         if (root->commit_root == root->node) {
 278                                 WARN_ON(bh_blocknr(root->node) !=
 279                                         btrfs_root_blocknr(&root->root_item));
 280                                 brelse(root->commit_root);
 281                                 root->commit_root = NULL;
 282
 283                                 /* make sure to update the root on disk
 284                                  * so we get any updates to the block used
 285                                  * counts
 286                                  */
 287                                 err = btrfs_update_root(trans,
 288                                                 root->fs_info->tree_root,
 289                                                 &root->root_key,
 290                                                 &root->root_item);
 291                                 continue;
 292                         }
 293                         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 294                         BUG_ON(!dirty);
 295                         dirty->root = kmalloc(sizeof(*dirty->root), GFP_NOFS);
 296                         BUG_ON(!dirty->root);
 297
 298                         memset(&root->root_item.drop_progress, 0,
 299                                sizeof(struct btrfs_disk_key));
 300                         root->root_item.drop_level = 0;
 301
 302                         memcpy(dirty->root, root, sizeof(*root));
 303                         dirty->root->node = root->commit_root;
 304                         dirty->latest_root = root;
 305                         root->commit_root = NULL;
 306
 307                         root->root_key.offset = root->fs_info->generation;
 308                         btrfs_set_root_blocknr(&root->root_item,
 309                                                bh_blocknr(root->node));
 310                         err = btrfs_insert_root(trans, root->fs_info->tree_root,
 311                                                 &root->root_key,
 312                                                 &root->root_item);
 313                         if (err)
 314                                 break;
 315
 316                         refs = btrfs_root_refs(&dirty->root->root_item);
 317                         btrfs_set_root_refs(&dirty->root->root_item, refs - 1);
 318                         err = btrfs_update_root(trans, root->fs_info->tree_root,
 319                                                 &dirty->root->root_key,
 320                                                 &dirty->root->root_item);
 321
 322                         BUG_ON(err);
 323                         if (refs == 1) {
 324                                 list_add(&dirty->list, list);
 325                         } else {
 326                                 WARN_ON(1);
 327                                 kfree(dirty->root);
 328                                 kfree(dirty);
 329                         }
 330                 }
 331         }
 332         return err;
 333 }
 334
 335 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 336 {
 337         struct btrfs_fs_info *info = root->fs_info;
 338         int ret;
 339         struct btrfs_trans_handle *trans;
 340
 341         if (root->defrag_running)
 342                 return 0;
 343
 344         trans = btrfs_start_transaction(root, 1);
 345         while (1) {
 346                 root->defrag_running = 1;
 347                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 348                 btrfs_end_transaction(trans, root);
 349                 mutex_unlock(&info->fs_mutex);
 350
 351                 btrfs_btree_balance_dirty(root);
 352                 cond_resched();
 353
 354                 mutex_lock(&info->fs_mutex);
 355                 trans = btrfs_start_transaction(root, 1);
 356                 if (ret != -EAGAIN)
 357                         break;
 358         }
 359         root->defrag_running = 0;
 360         radix_tree_tag_clear(&info->fs_roots_radix,
 361                      (unsigned long)root->root_key.objectid,
 362                      BTRFS_ROOT_DEFRAG_TAG);
 363         btrfs_end_transaction(trans, root);
 364         return 0;
 365 }
 366
 367 int btrfs_defrag_dirty_roots(struct btrfs_fs_info *info)
 368 {
 369         struct btrfs_root *gang[1];
 370         struct btrfs_root *root;
 371         int i;
 372         int ret;
 373         int err = 0;
 374         u64 last = 0;
 375
 376         while(1) {
 377                 ret = radix_tree_gang_lookup_tag(&info->fs_roots_radix,
 378                                                  (void **)gang, last,
 379                                                  ARRAY_SIZE(gang),
 380                                                  BTRFS_ROOT_DEFRAG_TAG);
 381                 if (ret == 0)
 382                         break;
 383                 for (i = 0; i < ret; i++) {
 384                         root = gang[i];
 385                         last = root->root_key.objectid + 1;
 386                         btrfs_defrag_root(root, 1);
 387                 }
 388         }
 389         btrfs_defrag_root(info->extent_root, 1);
 390         return err;
 391 }
 392
 393 static int drop_dirty_roots(struct btrfs_root *tree_root,
 394                             struct list_head *list)
 395 {
 396         struct dirty_root *dirty;
 397         struct btrfs_trans_handle *trans;
 398         u64 num_blocks;
 399         u64 blocks_used;
 400         int ret = 0;
 401         int err;
 402
 403         while(!list_empty(list)) {
 404                 struct btrfs_root *root;
 405
 406                 mutex_lock(&tree_root->fs_info->fs_mutex);
 407                 dirty = list_entry(list->next, struct dirty_root, list);
 408                 list_del_init(&dirty->list);
 409
 410                 num_blocks = btrfs_root_blocks_used(&dirty->root->root_item);
 411                 root = dirty->latest_root;
 412
 413                 while(1) {
 414                         trans = btrfs_start_transaction(tree_root, 1);
 415
 416                         ret = btrfs_drop_snapshot(trans, dirty->root);
 417                         if (ret != -EAGAIN) {
 418                                 break;
 419                         }
 420
 421                         err = btrfs_update_root(trans,
 422                                         tree_root,
 423                                         &dirty->root->root_key,
 424                                         &dirty->root->root_item);
 425                         if (err)
 426                                 ret = err;
 427                         ret = btrfs_end_transaction(trans, tree_root);
 428                         BUG_ON(ret);
 429                         mutex_unlock(&tree_root->fs_info->fs_mutex);
 430
 431                         btrfs_btree_balance_dirty(tree_root);
 432                         schedule();
 433
 434                         mutex_lock(&tree_root->fs_info->fs_mutex);
 435                 }
 436                 BUG_ON(ret);
 437
 438                 num_blocks -= btrfs_root_blocks_used(&dirty->root->root_item);
 439                 blocks_used = btrfs_root_blocks_used(&root->root_item);
 440                 if (num_blocks) {
 441                         record_root_in_trans(root);
 442                         btrfs_set_root_blocks_used(&root->root_item,
 443                                                    blocks_used - num_blocks);
 444                 }
 445                 ret = btrfs_del_root(trans, tree_root, &dirty->root->root_key);
 446                 if (ret) {
 447                         BUG();
 448                         break;
 449                 }
 450                 ret = btrfs_end_transaction(trans, tree_root);
 451                 BUG_ON(ret);
 452
 453                 kfree(dirty->root);
 454                 kfree(dirty);
 455                 mutex_unlock(&tree_root->fs_info->fs_mutex);
 456                 btrfs_btree_balance_dirty(tree_root);
 457                 schedule();
 458         }
 459         return ret;
 460 }
 461
 462 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 463                              struct btrfs_root *root)
 464 {
 465         unsigned long joined = 0;
 466         unsigned long timeout = 1;
 467         struct btrfs_transaction *cur_trans;
 468         struct btrfs_transaction *prev_trans = NULL;
 469         struct list_head dirty_fs_roots;
 470         struct radix_tree_root pinned_copy;
 471         DEFINE_WAIT(wait);
 472         int ret;
 473
 474         init_bit_radix(&pinned_copy);
 475         INIT_LIST_HEAD(&dirty_fs_roots);
 476
 477         mutex_lock(&root->fs_info->trans_mutex);
 478         if (trans->transaction->in_commit) {
 479                 cur_trans = trans->transaction;
 480                 trans->transaction->use_count++;
 481                 mutex_unlock(&root->fs_info->trans_mutex);
 482                 btrfs_end_transaction(trans, root);
 483
 484                 mutex_unlock(&root->fs_info->fs_mutex);
 485                 ret = wait_for_commit(root, cur_trans);
 486                 BUG_ON(ret);
 487
 488                 mutex_lock(&root->fs_info->trans_mutex);
 489                 put_transaction(cur_trans);
 490                 mutex_unlock(&root->fs_info->trans_mutex);
 491
 492                 mutex_lock(&root->fs_info->fs_mutex);
 493                 return 0;
 494         }
 495         trans->transaction->in_commit = 1;
 496         cur_trans = trans->transaction;
 497         if (cur_trans->list.prev != &root->fs_info->trans_list) {
 498                 prev_trans = list_entry(cur_trans->list.prev,
 499                                         struct btrfs_transaction, list);
 500                 if (!prev_trans->commit_done) {
 501                         prev_trans->use_count++;
 502                         mutex_unlock(&root->fs_info->fs_mutex);
 503                         mutex_unlock(&root->fs_info->trans_mutex);
 504
 505                         wait_for_commit(root, prev_trans);
 506
 507                         mutex_lock(&root->fs_info->fs_mutex);
 508                         mutex_lock(&root->fs_info->trans_mutex);
 509                         put_transaction(prev_trans);
 510                 }
 511         }
 512
 513         do {
 514                 joined = cur_trans->num_joined;
 515                 WARN_ON(cur_trans != trans->transaction);
 516                 prepare_to_wait(&cur_trans->writer_wait, &wait,
 517                                 TASK_UNINTERRUPTIBLE);
 518
 519                 if (cur_trans->num_writers > 1)
 520                         timeout = MAX_SCHEDULE_TIMEOUT;
 521                 else
 522                         timeout = 1;
 523
 524                 mutex_unlock(&root->fs_info->fs_mutex);
 525                 mutex_unlock(&root->fs_info->trans_mutex);
 526
 527                 schedule_timeout(timeout);
 528
 529                 mutex_lock(&root->fs_info->fs_mutex);
 530                 mutex_lock(&root->fs_info->trans_mutex);
 531                 finish_wait(&cur_trans->writer_wait, &wait);
 532         } while (cur_trans->num_writers > 1 ||
 533                  (cur_trans->num_joined != joined));
 534
 535         WARN_ON(cur_trans != trans->transaction);
 536         ret = add_dirty_roots(trans, &root->fs_info->fs_roots_radix,
 537                               &dirty_fs_roots);
 538         BUG_ON(ret);
 539
 540         ret = btrfs_commit_tree_roots(trans, root);
 541         BUG_ON(ret);
 542
 543         cur_trans = root->fs_info->running_transaction;
 544         root->fs_info->running_transaction = NULL;
 545         btrfs_set_super_generation(&root->fs_info->super_copy,
 546                                    cur_trans->transid);
 547         btrfs_set_super_root(&root->fs_info->super_copy,
 548                              bh_blocknr(root->fs_info->tree_root->node));
 549         memcpy(root->fs_info->disk_super, &root->fs_info->super_copy,
 550                sizeof(root->fs_info->super_copy));
 551
 552         btrfs_copy_pinned(root, &pinned_copy);
 553
 554         mutex_unlock(&root->fs_info->trans_mutex);
 555         mutex_unlock(&root->fs_info->fs_mutex);
 556         ret = btrfs_write_and_wait_transaction(trans, root);
 557         BUG_ON(ret);
 558         write_ctree_super(trans, root);
 559         mutex_lock(&root->fs_info->fs_mutex);
 560         btrfs_finish_extent_commit(trans, root, &pinned_copy);
 561         mutex_lock(&root->fs_info->trans_mutex);
 562         cur_trans->commit_done = 1;
 563         root->fs_info->last_trans_committed = cur_trans->transid;
 564         wake_up(&cur_trans->commit_wait);
 565         put_transaction(cur_trans);
 566         put_transaction(cur_trans);
 567
 568         if (root->fs_info->closing)
 569                 list_splice_init(&root->fs_info->dead_roots, &dirty_fs_roots);
 570         else
 571                 list_splice_init(&dirty_fs_roots, &root->fs_info->dead_roots);
 572
 573         mutex_unlock(&root->fs_info->trans_mutex);
 574         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 575
 576         if (root->fs_info->closing) {
 577                 mutex_unlock(&root->fs_info->fs_mutex);
 578                 drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
 579                 mutex_lock(&root->fs_info->fs_mutex);
 580         }
 581         return ret;
 582 }
 583
 584 int btrfs_clean_old_snapshots(struct btrfs_root *root)
 585 {
 586         struct list_head dirty_roots;
 587         INIT_LIST_HEAD(&dirty_roots);
 588
 589         mutex_lock(&root->fs_info->trans_mutex);
 590         list_splice_init(&root->fs_info->dead_roots, &dirty_roots);
 591         mutex_unlock(&root->fs_info->trans_mutex);
 592
 593         if (!list_empty(&dirty_roots)) {
 594                 drop_dirty_roots(root, &dirty_roots);
 595         }
 596         return 0;
 597 }
 598 void btrfs_transaction_cleaner(struct work_struct *work)
 599 {
 600         struct btrfs_fs_info *fs_info = container_of(work,
 601                                                      struct btrfs_fs_info,
 602                                                      trans_work.work);
 603
 604         struct btrfs_root *root = fs_info->tree_root;
 605         struct btrfs_transaction *cur;
 606         struct btrfs_trans_handle *trans;
 607         unsigned long now;
 608         unsigned long delay = HZ * 30;
 609         int ret;
 610
 611         mutex_lock(&root->fs_info->fs_mutex);
 612         mutex_lock(&root->fs_info->trans_mutex);
 613         cur = root->fs_info->running_transaction;
 614         if (!cur) {
 615                 mutex_unlock(&root->fs_info->trans_mutex);
 616                 goto out;
 617         }
 618         now = get_seconds();
 619         if (now < cur->start_time || now - cur->start_time < 30) {
 620                 mutex_unlock(&root->fs_info->trans_mutex);
 621                 delay = HZ * 5;
 622                 goto out;
 623         }
 624         mutex_unlock(&root->fs_info->trans_mutex);
 625         btrfs_defrag_dirty_roots(root->fs_info);
 626         trans = btrfs_start_transaction(root, 1);
 627         ret = btrfs_commit_transaction(trans, root);
 628 out:
 629         mutex_unlock(&root->fs_info->fs_mutex);
 630         btrfs_clean_old_snapshots(root);
 631         btrfs_transaction_queue_work(root, delay);
 632 }
 633
 634 void btrfs_transaction_queue_work(struct btrfs_root *root, int delay)
 635 {
 636         queue_delayed_work(trans_wq, &root->fs_info->trans_work, delay);
 637 }
 638
 639 void btrfs_transaction_flush_work(struct btrfs_root *root)
 640 {
 641         cancel_rearming_delayed_workqueue(trans_wq, &root->fs_info->trans_work);
 642         flush_workqueue(trans_wq);
 643 }
 644
 645 void __init btrfs_init_transaction_sys(void)
 646 {
 647         trans_wq = create_workqueue("btrfs");
 648 }
 649
 650 void __exit btrfs_exit_transaction_sys(void)
 651 {
 652         destroy_workqueue(trans_wq);
 653 }
 654