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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 <linux/writeback.h>
  22 #include "ctree.h"
  23 #include "disk-io.h"
  24 #include "transaction.h"
  25
  26 static int total_trans = 0;
  27 extern struct kmem_cache *btrfs_trans_handle_cachep;
  28 extern struct kmem_cache *btrfs_transaction_cachep;
  29
  30 static struct workqueue_struct *trans_wq;
  31
  32 #define BTRFS_ROOT_TRANS_TAG 0
  33 #define BTRFS_ROOT_DEFRAG_TAG 1
  34
  35 static void put_transaction(struct btrfs_transaction *transaction)
  36 {
  37         WARN_ON(transaction->use_count == 0);
  38         transaction->use_count--;
  39         if (transaction->use_count == 0) {
  40                 WARN_ON(total_trans == 0);
  41                 total_trans--;
  42                 list_del_init(&transaction->list);
  43                 memset(transaction, 0, sizeof(*transaction));
  44                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  45         }
  46 }
  47
  48 static int join_transaction(struct btrfs_root *root)
  49 {
  50         struct btrfs_transaction *cur_trans;
  51         cur_trans = root->fs_info->running_transaction;
  52         if (!cur_trans) {
  53                 cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
  54                                              GFP_NOFS);
  55                 total_trans++;
  56                 BUG_ON(!cur_trans);
  57                 root->fs_info->generation++;
  58                 root->fs_info->running_transaction = cur_trans;
  59                 cur_trans->num_writers = 1;
  60                 cur_trans->num_joined = 0;
  61                 cur_trans->transid = root->fs_info->generation;
  62                 init_waitqueue_head(&cur_trans->writer_wait);
  63                 init_waitqueue_head(&cur_trans->commit_wait);
  64                 cur_trans->in_commit = 0;
  65                 cur_trans->use_count = 1;
  66                 cur_trans->commit_done = 0;
  67                 cur_trans->start_time = get_seconds();
  68                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
  69                 init_bit_radix(&cur_trans->dirty_pages);
  70         } else {
  71                 cur_trans->num_writers++;
  72                 cur_trans->num_joined++;
  73         }
  74
  75         return 0;
  76 }
  77
  78 static int record_root_in_trans(struct btrfs_root *root)
  79 {
  80         u64 running_trans_id = root->fs_info->running_transaction->transid;
  81         if (root->ref_cows && root->last_trans < running_trans_id) {
  82                 WARN_ON(root == root->fs_info->extent_root);
  83                 if (root->root_item.refs != 0) {
  84                         radix_tree_tag_set(&root->fs_info->fs_roots_radix,
  85                                    (unsigned long)root->root_key.objectid,
  86                                    BTRFS_ROOT_TRANS_TAG);
  87                         radix_tree_tag_set(&root->fs_info->fs_roots_radix,
  88                                    (unsigned long)root->root_key.objectid,
  89                                    BTRFS_ROOT_DEFRAG_TAG);
  90                         root->commit_root = root->node;
  91                         get_bh(root->node);
  92                 } else {
  93                         WARN_ON(1);
  94                 }
  95                 root->last_trans = running_trans_id;
  96         }
  97         return 0;
  98 }
  99
 100 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 101                                                    int num_blocks)
 102 {
 103         struct btrfs_trans_handle *h =
 104                 kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 105         int ret;
 106
 107         mutex_lock(&root->fs_info->trans_mutex);
 108         ret = join_transaction(root);
 109         BUG_ON(ret);
 110
 111         record_root_in_trans(root);
 112         h->transid = root->fs_info->running_transaction->transid;
 113         h->transaction = root->fs_info->running_transaction;
 114         h->blocks_reserved = num_blocks;
 115         h->blocks_used = 0;
 116         h->block_group = NULL;
 117         h->alloc_exclude_nr = 0;
 118         h->alloc_exclude_start = 0;
 119         root->fs_info->running_transaction->use_count++;
 120         mutex_unlock(&root->fs_info->trans_mutex);
 121         return h;
 122 }
 123
 124 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 125                           struct btrfs_root *root)
 126 {
 127         struct btrfs_transaction *cur_trans;
 128
 129         mutex_lock(&root->fs_info->trans_mutex);
 130         cur_trans = root->fs_info->running_transaction;
 131         WARN_ON(cur_trans != trans->transaction);
 132         WARN_ON(cur_trans->num_writers < 1);
 133         cur_trans->num_writers--;
 134         if (waitqueue_active(&cur_trans->writer_wait))
 135                 wake_up(&cur_trans->writer_wait);
 136         put_transaction(cur_trans);
 137         mutex_unlock(&root->fs_info->trans_mutex);
 138         memset(trans, 0, sizeof(*trans));
 139         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 140         return 0;
 141 }
 142
 143
 144 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 145                                      struct btrfs_root *root)
 146 {
 147         unsigned long gang[16];
 148         int ret;
 149         int i;
 150         int err;
 151         int werr = 0;
 152         struct page *page;
 153         struct radix_tree_root *dirty_pages;
 154         struct inode *btree_inode = root->fs_info->btree_inode;
 155
 156         if (!trans || !trans->transaction) {
 157                 return filemap_write_and_wait(btree_inode->i_mapping);
 158         }
 159         dirty_pages = &trans->transaction->dirty_pages;
 160         while(1) {
 161                 ret = find_first_radix_bit(dirty_pages, gang,
 162                                            0, ARRAY_SIZE(gang));
 163                 if (!ret)
 164                         break;
 165                 for (i = 0; i < ret; i++) {
 166                         /* FIXME EIO */
 167                         clear_radix_bit(dirty_pages, gang[i]);
 168                         page = find_lock_page(btree_inode->i_mapping,
 169                                               gang[i]);
 170                         if (!page)
 171                                 continue;
 172                         if (PageWriteback(page)) {
 173                                 if (PageDirty(page))
 174                                         wait_on_page_writeback(page);
 175                                 else {
 176                                         unlock_page(page);
 177                                         page_cache_release(page);
 178                                         continue;
 179                                 }
 180                         }
 181                         err = write_one_page(page, 0);
 182                         if (err)
 183                                 werr = err;
 184                         page_cache_release(page);
 185                 }
 186         }
 187         err = filemap_fdatawait(btree_inode->i_mapping);
 188         if (err)
 189                 werr = err;
 190         return werr;
 191 }
 192
 193 int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
 194                             struct btrfs_root *root)
 195 {
 196         int ret;
 197         u64 old_extent_block;
 198         struct btrfs_fs_info *fs_info = root->fs_info;
 199         struct btrfs_root *tree_root = fs_info->tree_root;
 200         struct btrfs_root *extent_root = fs_info->extent_root;
 201
 202         btrfs_write_dirty_block_groups(trans, extent_root);
 203         while(1) {
 204                 old_extent_block = btrfs_root_blocknr(&extent_root->root_item);
 205                 if (old_extent_block == bh_blocknr(extent_root->node))
 206                         break;
 207                 btrfs_set_root_blocknr(&extent_root->root_item,
 208                                        bh_blocknr(extent_root->node));
 209                 ret = btrfs_update_root(trans, tree_root,
 210                                         &extent_root->root_key,
 211                                         &extent_root->root_item);
 212                 BUG_ON(ret);
 213                 btrfs_write_dirty_block_groups(trans, extent_root);
 214         }
 215         return 0;
 216 }
 217
 218 static int wait_for_commit(struct btrfs_root *root,
 219                            struct btrfs_transaction *commit)
 220 {
 221         DEFINE_WAIT(wait);
 222         mutex_lock(&root->fs_info->trans_mutex);
 223         while(!commit->commit_done) {
 224                 prepare_to_wait(&commit->commit_wait, &wait,
 225                                 TASK_UNINTERRUPTIBLE);
 226                 if (commit->commit_done)
 227                         break;
 228                 mutex_unlock(&root->fs_info->trans_mutex);
 229                 schedule();
 230                 mutex_lock(&root->fs_info->trans_mutex);
 231         }
 232         mutex_unlock(&root->fs_info->trans_mutex);
 233         finish_wait(&commit->commit_wait, &wait);
 234         return 0;
 235 }
 236
 237 struct dirty_root {
 238         struct list_head list;
 239         struct btrfs_root *root;
 240         struct btrfs_root *latest_root;
 241 };
 242
 243 int btrfs_add_dead_root(struct btrfs_root *root,
 244                         struct btrfs_root *latest,
 245                         struct list_head *dead_list)
 246 {
 247         struct dirty_root *dirty;
 248
 249         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 250         if (!dirty)
 251                 return -ENOMEM;
 252         dirty->root = root;
 253         dirty->latest_root = latest;
 254         list_add(&dirty->list, dead_list);
 255         return 0;
 256 }
 257
 258 static int add_dirty_roots(struct btrfs_trans_handle *trans,
 259                            struct radix_tree_root *radix,
 260                            struct list_head *list)
 261 {
 262         struct dirty_root *dirty;
 263         struct btrfs_root *gang[8];
 264         struct btrfs_root *root;
 265         int i;
 266         int ret;
 267         int err = 0;
 268         u32 refs;
 269
 270         while(1) {
 271                 ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
 272                                                  ARRAY_SIZE(gang),
 273                                                  BTRFS_ROOT_TRANS_TAG);
 274                 if (ret == 0)
 275                         break;
 276                 for (i = 0; i < ret; i++) {
 277                         root = gang[i];
 278                         radix_tree_tag_clear(radix,
 279                                      (unsigned long)root->root_key.objectid,
 280                                      BTRFS_ROOT_TRANS_TAG);
 281                         if (root->commit_root == root->node) {
 282                                 WARN_ON(bh_blocknr(root->node) !=
 283                                         btrfs_root_blocknr(&root->root_item));
 284                                 brelse(root->commit_root);
 285                                 root->commit_root = NULL;
 286
 287                                 /* make sure to update the root on disk
 288                                  * so we get any updates to the block used
 289                                  * counts
 290                                  */
 291                                 err = btrfs_update_root(trans,
 292                                                 root->fs_info->tree_root,
 293                                                 &root->root_key,
 294                                                 &root->root_item);
 295                                 continue;
 296                         }
 297                         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 298                         BUG_ON(!dirty);
 299                         dirty->root = kmalloc(sizeof(*dirty->root), GFP_NOFS);
 300                         BUG_ON(!dirty->root);
 301
 302                         memset(&root->root_item.drop_progress, 0,
 303                                sizeof(struct btrfs_disk_key));
 304                         root->root_item.drop_level = 0;
 305
 306                         memcpy(dirty->root, root, sizeof(*root));
 307                         dirty->root->node = root->commit_root;
 308                         dirty->latest_root = root;
 309                         root->commit_root = NULL;
 310
 311                         root->root_key.offset = root->fs_info->generation;
 312                         btrfs_set_root_blocknr(&root->root_item,
 313                                                bh_blocknr(root->node));
 314                         err = btrfs_insert_root(trans, root->fs_info->tree_root,
 315                                                 &root->root_key,
 316                                                 &root->root_item);
 317                         if (err)
 318                                 break;
 319
 320                         refs = btrfs_root_refs(&dirty->root->root_item);
 321                         btrfs_set_root_refs(&dirty->root->root_item, refs - 1);
 322                         err = btrfs_update_root(trans, root->fs_info->tree_root,
 323                                                 &dirty->root->root_key,
 324                                                 &dirty->root->root_item);
 325
 326                         BUG_ON(err);
 327                         if (refs == 1) {
 328                                 list_add(&dirty->list, list);
 329                         } else {
 330                                 WARN_ON(1);
 331                                 kfree(dirty->root);
 332                                 kfree(dirty);
 333                         }
 334                 }
 335         }
 336         return err;
 337 }
 338
 339 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 340 {
 341         struct btrfs_fs_info *info = root->fs_info;
 342         int ret;
 343         struct btrfs_trans_handle *trans;
 344         unsigned long nr;
 345
 346         if (root->defrag_running)
 347                 return 0;
 348
 349         trans = btrfs_start_transaction(root, 1);
 350         while (1) {
 351                 root->defrag_running = 1;
 352                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 353                 nr = trans->blocks_used;
 354                 btrfs_end_transaction(trans, root);
 355                 mutex_unlock(&info->fs_mutex);
 356
 357                 btrfs_btree_balance_dirty(info->tree_root, nr);
 358                 cond_resched();
 359
 360                 mutex_lock(&info->fs_mutex);
 361                 trans = btrfs_start_transaction(root, 1);
 362                 if (ret != -EAGAIN)
 363                         break;
 364         }
 365         root->defrag_running = 0;
 366         radix_tree_tag_clear(&info->fs_roots_radix,
 367                      (unsigned long)root->root_key.objectid,
 368                      BTRFS_ROOT_DEFRAG_TAG);
 369         btrfs_end_transaction(trans, root);
 370         return 0;
 371 }
 372
 373 int btrfs_defrag_dirty_roots(struct btrfs_fs_info *info)
 374 {
 375         struct btrfs_root *gang[1];
 376         struct btrfs_root *root;
 377         int i;
 378         int ret;
 379         int err = 0;
 380         u64 last = 0;
 381
 382         while(1) {
 383                 ret = radix_tree_gang_lookup_tag(&info->fs_roots_radix,
 384                                                  (void **)gang, last,
 385                                                  ARRAY_SIZE(gang),
 386                                                  BTRFS_ROOT_DEFRAG_TAG);
 387                 if (ret == 0)
 388                         break;
 389                 for (i = 0; i < ret; i++) {
 390                         root = gang[i];
 391                         last = root->root_key.objectid + 1;
 392                         btrfs_defrag_root(root, 1);
 393                 }
 394         }
 395         btrfs_defrag_root(info->extent_root, 1);
 396         return err;
 397 }
 398
 399 static int drop_dirty_roots(struct btrfs_root *tree_root,
 400                             struct list_head *list)
 401 {
 402         struct dirty_root *dirty;
 403         struct btrfs_trans_handle *trans;
 404         unsigned long nr;
 405         u64 num_blocks;
 406         u64 blocks_used;
 407         int ret = 0;
 408         int err;
 409
 410         while(!list_empty(list)) {
 411                 struct btrfs_root *root;
 412
 413                 mutex_lock(&tree_root->fs_info->fs_mutex);
 414                 dirty = list_entry(list->next, struct dirty_root, list);
 415                 list_del_init(&dirty->list);
 416
 417                 num_blocks = btrfs_root_blocks_used(&dirty->root->root_item);
 418                 root = dirty->latest_root;
 419
 420                 while(1) {
 421                         trans = btrfs_start_transaction(tree_root, 1);
 422                         ret = btrfs_drop_snapshot(trans, dirty->root);
 423                         if (ret != -EAGAIN) {
 424                                 break;
 425                         }
 426
 427                         err = btrfs_update_root(trans,
 428                                         tree_root,
 429                                         &dirty->root->root_key,
 430                                         &dirty->root->root_item);
 431                         if (err)
 432                                 ret = err;
 433                         nr = trans->blocks_used;
 434                         ret = btrfs_end_transaction(trans, tree_root);
 435                         BUG_ON(ret);
 436                         mutex_unlock(&tree_root->fs_info->fs_mutex);
 437                         btrfs_btree_balance_dirty(tree_root, nr);
 438                         schedule();
 439
 440                         mutex_lock(&tree_root->fs_info->fs_mutex);
 441                 }
 442                 BUG_ON(ret);
 443
 444                 num_blocks -= btrfs_root_blocks_used(&dirty->root->root_item);
 445                 blocks_used = btrfs_root_blocks_used(&root->root_item);
 446                 if (num_blocks) {
 447                         record_root_in_trans(root);
 448                         btrfs_set_root_blocks_used(&root->root_item,
 449                                                    blocks_used - num_blocks);
 450                 }
 451                 ret = btrfs_del_root(trans, tree_root, &dirty->root->root_key);
 452                 if (ret) {
 453                         BUG();
 454                         break;
 455                 }
 456                 nr = trans->blocks_used;
 457                 ret = btrfs_end_transaction(trans, tree_root);
 458                 BUG_ON(ret);
 459
 460                 kfree(dirty->root);
 461                 kfree(dirty);
 462                 mutex_unlock(&tree_root->fs_info->fs_mutex);
 463
 464                 btrfs_btree_balance_dirty(tree_root, nr);
 465                 schedule();
 466         }
 467         return ret;
 468 }
 469
 470 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 471                              struct btrfs_root *root)
 472 {
 473         unsigned long joined = 0;
 474         unsigned long timeout = 1;
 475         struct btrfs_transaction *cur_trans;
 476         struct btrfs_transaction *prev_trans = NULL;
 477         struct list_head dirty_fs_roots;
 478         struct radix_tree_root pinned_copy;
 479         DEFINE_WAIT(wait);
 480         int ret;
 481
 482         init_bit_radix(&pinned_copy);
 483         INIT_LIST_HEAD(&dirty_fs_roots);
 484
 485         mutex_lock(&root->fs_info->trans_mutex);
 486         if (trans->transaction->in_commit) {
 487                 cur_trans = trans->transaction;
 488                 trans->transaction->use_count++;
 489                 mutex_unlock(&root->fs_info->trans_mutex);
 490                 btrfs_end_transaction(trans, root);
 491
 492                 mutex_unlock(&root->fs_info->fs_mutex);
 493                 ret = wait_for_commit(root, cur_trans);
 494                 BUG_ON(ret);
 495
 496                 mutex_lock(&root->fs_info->trans_mutex);
 497                 put_transaction(cur_trans);
 498                 mutex_unlock(&root->fs_info->trans_mutex);
 499
 500                 mutex_lock(&root->fs_info->fs_mutex);
 501                 return 0;
 502         }
 503         trans->transaction->in_commit = 1;
 504         cur_trans = trans->transaction;
 505         if (cur_trans->list.prev != &root->fs_info->trans_list) {
 506                 prev_trans = list_entry(cur_trans->list.prev,
 507                                         struct btrfs_transaction, list);
 508                 if (!prev_trans->commit_done) {
 509                         prev_trans->use_count++;
 510                         mutex_unlock(&root->fs_info->fs_mutex);
 511                         mutex_unlock(&root->fs_info->trans_mutex);
 512
 513                         wait_for_commit(root, prev_trans);
 514
 515                         mutex_lock(&root->fs_info->fs_mutex);
 516                         mutex_lock(&root->fs_info->trans_mutex);
 517                         put_transaction(prev_trans);
 518                 }
 519         }
 520
 521         do {
 522                 joined = cur_trans->num_joined;
 523                 WARN_ON(cur_trans != trans->transaction);
 524                 prepare_to_wait(&cur_trans->writer_wait, &wait,
 525                                 TASK_UNINTERRUPTIBLE);
 526
 527                 if (cur_trans->num_writers > 1)
 528                         timeout = MAX_SCHEDULE_TIMEOUT;
 529                 else
 530                         timeout = 1;
 531
 532                 mutex_unlock(&root->fs_info->fs_mutex);
 533                 mutex_unlock(&root->fs_info->trans_mutex);
 534
 535                 schedule_timeout(timeout);
 536
 537                 mutex_lock(&root->fs_info->fs_mutex);
 538                 mutex_lock(&root->fs_info->trans_mutex);
 539                 finish_wait(&cur_trans->writer_wait, &wait);
 540         } while (cur_trans->num_writers > 1 ||
 541                  (cur_trans->num_joined != joined));
 542
 543         WARN_ON(cur_trans != trans->transaction);
 544         ret = add_dirty_roots(trans, &root->fs_info->fs_roots_radix,
 545                               &dirty_fs_roots);
 546         BUG_ON(ret);
 547
 548         ret = btrfs_commit_tree_roots(trans, root);
 549         BUG_ON(ret);
 550
 551         cur_trans = root->fs_info->running_transaction;
 552         root->fs_info->running_transaction = NULL;
 553         btrfs_set_super_generation(&root->fs_info->super_copy,
 554                                    cur_trans->transid);
 555         btrfs_set_super_root(&root->fs_info->super_copy,
 556                              bh_blocknr(root->fs_info->tree_root->node));
 557         memcpy(root->fs_info->disk_super, &root->fs_info->super_copy,
 558                sizeof(root->fs_info->super_copy));
 559
 560         btrfs_copy_pinned(root, &pinned_copy);
 561
 562         mutex_unlock(&root->fs_info->trans_mutex);
 563         mutex_unlock(&root->fs_info->fs_mutex);
 564         ret = btrfs_write_and_wait_transaction(trans, root);
 565         BUG_ON(ret);
 566         write_ctree_super(trans, root);
 567         mutex_lock(&root->fs_info->fs_mutex);
 568         btrfs_finish_extent_commit(trans, root, &pinned_copy);
 569         mutex_lock(&root->fs_info->trans_mutex);
 570         cur_trans->commit_done = 1;
 571         root->fs_info->last_trans_committed = cur_trans->transid;
 572         wake_up(&cur_trans->commit_wait);
 573         put_transaction(cur_trans);
 574         put_transaction(cur_trans);
 575
 576         if (root->fs_info->closing)
 577                 list_splice_init(&root->fs_info->dead_roots, &dirty_fs_roots);
 578         else
 579                 list_splice_init(&dirty_fs_roots, &root->fs_info->dead_roots);
 580
 581         mutex_unlock(&root->fs_info->trans_mutex);
 582         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 583
 584         if (root->fs_info->closing) {
 585                 mutex_unlock(&root->fs_info->fs_mutex);
 586                 drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
 587                 mutex_lock(&root->fs_info->fs_mutex);
 588         }
 589         return ret;
 590 }
 591
 592 int btrfs_clean_old_snapshots(struct btrfs_root *root)
 593 {
 594         struct list_head dirty_roots;
 595         INIT_LIST_HEAD(&dirty_roots);
 596
 597         mutex_lock(&root->fs_info->trans_mutex);
 598         list_splice_init(&root->fs_info->dead_roots, &dirty_roots);
 599         mutex_unlock(&root->fs_info->trans_mutex);
 600
 601         if (!list_empty(&dirty_roots)) {
 602                 drop_dirty_roots(root, &dirty_roots);
 603         }
 604         return 0;
 605 }
 606 void btrfs_transaction_cleaner(struct work_struct *work)
 607 {
 608         struct btrfs_fs_info *fs_info = container_of(work,
 609                                                      struct btrfs_fs_info,
 610                                                      trans_work.work);
 611
 612         struct btrfs_root *root = fs_info->tree_root;
 613         struct btrfs_transaction *cur;
 614         struct btrfs_trans_handle *trans;
 615         unsigned long now;
 616         unsigned long delay = HZ * 30;
 617         int ret;
 618
 619         mutex_lock(&root->fs_info->fs_mutex);
 620         mutex_lock(&root->fs_info->trans_mutex);
 621         cur = root->fs_info->running_transaction;
 622         if (!cur) {
 623                 mutex_unlock(&root->fs_info->trans_mutex);
 624                 goto out;
 625         }
 626         now = get_seconds();
 627         if (now < cur->start_time || now - cur->start_time < 30) {
 628                 mutex_unlock(&root->fs_info->trans_mutex);
 629                 delay = HZ * 5;
 630                 goto out;
 631         }
 632         mutex_unlock(&root->fs_info->trans_mutex);
 633         btrfs_defrag_dirty_roots(root->fs_info);
 634         trans = btrfs_start_transaction(root, 1);
 635         ret = btrfs_commit_transaction(trans, root);
 636 out:
 637         mutex_unlock(&root->fs_info->fs_mutex);
 638         btrfs_clean_old_snapshots(root);
 639         btrfs_transaction_queue_work(root, delay);
 640 }
 641
 642 void btrfs_transaction_queue_work(struct btrfs_root *root, int delay)
 643 {
 644         queue_delayed_work(trans_wq, &root->fs_info->trans_work, delay);
 645 }
 646
 647 void btrfs_transaction_flush_work(struct btrfs_root *root)
 648 {
 649         cancel_rearming_delayed_workqueue(trans_wq, &root->fs_info->trans_work);
 650         flush_workqueue(trans_wq);
 651 }
 652
 653 void __init btrfs_init_transaction_sys(void)
 654 {
 655         trans_wq = create_workqueue("btrfs");
 656 }
 657
 658 void __exit btrfs_exit_transaction_sys(void)
 659 {
 660         destroy_workqueue(trans_wq);
 661 }
 662