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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 <linux/pagemap.h>
  23 #include "ctree.h"
  24 #include "disk-io.h"
  25 #include "transaction.h"
  26 #include "locking.h"
  27
  28 static int total_trans = 0;
  29 extern struct kmem_cache *btrfs_trans_handle_cachep;
  30 extern struct kmem_cache *btrfs_transaction_cachep;
  31
  32 #define BTRFS_ROOT_TRANS_TAG 0
  33
  34 static noinline 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 noinline 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->last_alloc = 0;
  58                 root->fs_info->last_data_alloc = 0;
  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                 INIT_LIST_HEAD(&cur_trans->pending_snapshots);
  69                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
  70                 btrfs_ordered_inode_tree_init(&cur_trans->ordered_inode_tree);
  71                 extent_io_tree_init(&cur_trans->dirty_pages,
  72                                      root->fs_info->btree_inode->i_mapping,
  73                                      GFP_NOFS);
  74                 spin_lock(&root->fs_info->new_trans_lock);
  75                 root->fs_info->running_transaction = cur_trans;
  76                 spin_unlock(&root->fs_info->new_trans_lock);
  77         } else {
  78                 cur_trans->num_writers++;
  79                 cur_trans->num_joined++;
  80         }
  81
  82         return 0;
  83 }
  84
  85 static noinline int record_root_in_trans(struct btrfs_root *root)
  86 {
  87         u64 running_trans_id = root->fs_info->running_transaction->transid;
  88         if (root->ref_cows && root->last_trans < running_trans_id) {
  89                 WARN_ON(root == root->fs_info->extent_root);
  90                 if (root->root_item.refs != 0) {
  91                         radix_tree_tag_set(&root->fs_info->fs_roots_radix,
  92                                    (unsigned long)root->root_key.objectid,
  93                                    BTRFS_ROOT_TRANS_TAG);
  94                         root->commit_root = btrfs_root_node(root);
  95                 } else {
  96                         WARN_ON(1);
  97                 }
  98                 root->last_trans = running_trans_id;
  99         }
 100         return 0;
 101 }
 102
 103 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 104                                                    int num_blocks)
 105 {
 106         struct btrfs_trans_handle *h =
 107                 kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 108         int ret;
 109
 110         mutex_lock(&root->fs_info->trans_mutex);
 111         ret = join_transaction(root);
 112         BUG_ON(ret);
 113
 114         record_root_in_trans(root);
 115         h->transid = root->fs_info->running_transaction->transid;
 116         h->transaction = root->fs_info->running_transaction;
 117         h->blocks_reserved = num_blocks;
 118         h->blocks_used = 0;
 119         h->block_group = NULL;
 120         h->alloc_exclude_nr = 0;
 121         h->alloc_exclude_start = 0;
 122         root->fs_info->running_transaction->use_count++;
 123         mutex_unlock(&root->fs_info->trans_mutex);
 124         return h;
 125 }
 126
 127 static noinline int wait_for_commit(struct btrfs_root *root,
 128                                     struct btrfs_transaction *commit)
 129 {
 130         DEFINE_WAIT(wait);
 131         mutex_lock(&root->fs_info->trans_mutex);
 132         while(!commit->commit_done) {
 133                 prepare_to_wait(&commit->commit_wait, &wait,
 134                                 TASK_UNINTERRUPTIBLE);
 135                 if (commit->commit_done)
 136                         break;
 137                 mutex_unlock(&root->fs_info->trans_mutex);
 138                 schedule();
 139                 mutex_lock(&root->fs_info->trans_mutex);
 140         }
 141         mutex_unlock(&root->fs_info->trans_mutex);
 142         finish_wait(&commit->commit_wait, &wait);
 143         return 0;
 144 }
 145
 146 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 147                           struct btrfs_root *root, int throttle)
 148 {
 149         struct btrfs_transaction *cur_trans;
 150
 151         mutex_lock(&root->fs_info->trans_mutex);
 152         cur_trans = root->fs_info->running_transaction;
 153         WARN_ON(cur_trans != trans->transaction);
 154         WARN_ON(cur_trans->num_writers < 1);
 155         cur_trans->num_writers--;
 156
 157         if (waitqueue_active(&cur_trans->writer_wait))
 158                 wake_up(&cur_trans->writer_wait);
 159
 160         if (cur_trans->in_commit && throttle) {
 161                 int ret;
 162                 mutex_unlock(&root->fs_info->trans_mutex);
 163                 ret = wait_for_commit(root, cur_trans);
 164                 BUG_ON(ret);
 165                 mutex_lock(&root->fs_info->trans_mutex);
 166         }
 167
 168         put_transaction(cur_trans);
 169         mutex_unlock(&root->fs_info->trans_mutex);
 170         memset(trans, 0, sizeof(*trans));
 171         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 172         return 0;
 173 }
 174
 175 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 176                           struct btrfs_root *root)
 177 {
 178         return __btrfs_end_transaction(trans, root, 0);
 179 }
 180
 181 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 182                                    struct btrfs_root *root)
 183 {
 184         return __btrfs_end_transaction(trans, root, 1);
 185 }
 186
 187
 188 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 189                                      struct btrfs_root *root)
 190 {
 191         int ret;
 192         int err;
 193         int werr = 0;
 194         struct extent_io_tree *dirty_pages;
 195         struct page *page;
 196         struct inode *btree_inode = root->fs_info->btree_inode;
 197         u64 start;
 198         u64 end;
 199         unsigned long index;
 200
 201         if (!trans || !trans->transaction) {
 202                 return filemap_write_and_wait(btree_inode->i_mapping);
 203         }
 204         dirty_pages = &trans->transaction->dirty_pages;
 205         while(1) {
 206                 ret = find_first_extent_bit(dirty_pages, 0, &start, &end,
 207                                             EXTENT_DIRTY);
 208                 if (ret)
 209                         break;
 210                 clear_extent_dirty(dirty_pages, start, end, GFP_NOFS);
 211                 while(start <= end) {
 212                         index = start >> PAGE_CACHE_SHIFT;
 213                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 214                         page = find_lock_page(btree_inode->i_mapping, index);
 215                         if (!page)
 216                                 continue;
 217                         if (PageWriteback(page)) {
 218                                 if (PageDirty(page))
 219                                         wait_on_page_writeback(page);
 220                                 else {
 221                                         unlock_page(page);
 222                                         page_cache_release(page);
 223                                         continue;
 224                                 }
 225                         }
 226                         err = write_one_page(page, 0);
 227                         if (err)
 228                                 werr = err;
 229                         page_cache_release(page);
 230                 }
 231         }
 232         err = filemap_fdatawait(btree_inode->i_mapping);
 233         if (err)
 234                 werr = err;
 235         return werr;
 236 }
 237
 238 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 239                                struct btrfs_root *root)
 240 {
 241         int ret;
 242         u64 old_root_bytenr;
 243         struct btrfs_root *tree_root = root->fs_info->tree_root;
 244
 245         btrfs_write_dirty_block_groups(trans, root);
 246         while(1) {
 247                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 248                 if (old_root_bytenr == root->node->start)
 249                         break;
 250                 btrfs_set_root_bytenr(&root->root_item,
 251                                        root->node->start);
 252                 btrfs_set_root_level(&root->root_item,
 253                                      btrfs_header_level(root->node));
 254                 ret = btrfs_update_root(trans, tree_root,
 255                                         &root->root_key,
 256                                         &root->root_item);
 257                 BUG_ON(ret);
 258                 btrfs_write_dirty_block_groups(trans, root);
 259         }
 260         return 0;
 261 }
 262
 263 int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
 264                             struct btrfs_root *root)
 265 {
 266         struct btrfs_fs_info *fs_info = root->fs_info;
 267         struct list_head *next;
 268
 269         while(!list_empty(&fs_info->dirty_cowonly_roots)) {
 270                 next = fs_info->dirty_cowonly_roots.next;
 271                 list_del_init(next);
 272                 root = list_entry(next, struct btrfs_root, dirty_list);
 273                 update_cowonly_root(trans, root);
 274         }
 275         return 0;
 276 }
 277
 278 struct dirty_root {
 279         struct list_head list;
 280         struct btrfs_root *root;
 281         struct btrfs_root *latest_root;
 282 };
 283
 284 int btrfs_add_dead_root(struct btrfs_root *root,
 285                         struct btrfs_root *latest,
 286                         struct list_head *dead_list)
 287 {
 288         struct dirty_root *dirty;
 289
 290         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 291         if (!dirty)
 292                 return -ENOMEM;
 293         dirty->root = root;
 294         dirty->latest_root = latest;
 295         list_add(&dirty->list, dead_list);
 296         return 0;
 297 }
 298
 299 static noinline int add_dirty_roots(struct btrfs_trans_handle *trans,
 300                                     struct radix_tree_root *radix,
 301                                     struct list_head *list)
 302 {
 303         struct dirty_root *dirty;
 304         struct btrfs_root *gang[8];
 305         struct btrfs_root *root;
 306         int i;
 307         int ret;
 308         int err = 0;
 309         u32 refs;
 310
 311         while(1) {
 312                 ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
 313                                                  ARRAY_SIZE(gang),
 314                                                  BTRFS_ROOT_TRANS_TAG);
 315                 if (ret == 0)
 316                         break;
 317                 for (i = 0; i < ret; i++) {
 318                         root = gang[i];
 319                         radix_tree_tag_clear(radix,
 320                                      (unsigned long)root->root_key.objectid,
 321                                      BTRFS_ROOT_TRANS_TAG);
 322                         if (root->commit_root == root->node) {
 323                                 WARN_ON(root->node->start !=
 324                                         btrfs_root_bytenr(&root->root_item));
 325                                 free_extent_buffer(root->commit_root);
 326                                 root->commit_root = NULL;
 327
 328                                 /* make sure to update the root on disk
 329                                  * so we get any updates to the block used
 330                                  * counts
 331                                  */
 332                                 err = btrfs_update_root(trans,
 333                                                 root->fs_info->tree_root,
 334                                                 &root->root_key,
 335                                                 &root->root_item);
 336                                 continue;
 337                         }
 338                         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 339                         BUG_ON(!dirty);
 340                         dirty->root = kmalloc(sizeof(*dirty->root), GFP_NOFS);
 341                         BUG_ON(!dirty->root);
 342
 343                         memset(&root->root_item.drop_progress, 0,
 344                                sizeof(struct btrfs_disk_key));
 345                         root->root_item.drop_level = 0;
 346
 347                         memcpy(dirty->root, root, sizeof(*root));
 348                         dirty->root->node = root->commit_root;
 349                         dirty->latest_root = root;
 350                         root->commit_root = NULL;
 351
 352                         root->root_key.offset = root->fs_info->generation;
 353                         btrfs_set_root_bytenr(&root->root_item,
 354                                               root->node->start);
 355                         btrfs_set_root_level(&root->root_item,
 356                                              btrfs_header_level(root->node));
 357                         err = btrfs_insert_root(trans, root->fs_info->tree_root,
 358                                                 &root->root_key,
 359                                                 &root->root_item);
 360                         if (err)
 361                                 break;
 362
 363                         refs = btrfs_root_refs(&dirty->root->root_item);
 364                         btrfs_set_root_refs(&dirty->root->root_item, refs - 1);
 365                         err = btrfs_update_root(trans, root->fs_info->tree_root,
 366                                                 &dirty->root->root_key,
 367                                                 &dirty->root->root_item);
 368
 369                         BUG_ON(err);
 370                         if (refs == 1) {
 371                                 list_add(&dirty->list, list);
 372                         } else {
 373                                 WARN_ON(1);
 374                                 kfree(dirty->root);
 375                                 kfree(dirty);
 376                         }
 377                 }
 378         }
 379         return err;
 380 }
 381
 382 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 383 {
 384         struct btrfs_fs_info *info = root->fs_info;
 385         int ret;
 386         struct btrfs_trans_handle *trans;
 387         unsigned long nr;
 388
 389         smp_mb();
 390         if (root->defrag_running)
 391                 return 0;
 392         trans = btrfs_start_transaction(root, 1);
 393         while (1) {
 394                 root->defrag_running = 1;
 395                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 396                 nr = trans->blocks_used;
 397                 btrfs_end_transaction(trans, root);
 398                 btrfs_btree_balance_dirty(info->tree_root, nr);
 399                 cond_resched();
 400
 401                 trans = btrfs_start_transaction(root, 1);
 402                 if (root->fs_info->closing || ret != -EAGAIN)
 403                         break;
 404         }
 405         root->defrag_running = 0;
 406         smp_mb();
 407         btrfs_end_transaction(trans, root);
 408         return 0;
 409 }
 410
 411 static noinline int drop_dirty_roots(struct btrfs_root *tree_root,
 412                                      struct list_head *list)
 413 {
 414         struct dirty_root *dirty;
 415         struct btrfs_trans_handle *trans;
 416         unsigned long nr;
 417         u64 num_bytes;
 418         u64 bytes_used;
 419         int ret = 0;
 420         int err;
 421
 422         while(!list_empty(list)) {
 423                 struct btrfs_root *root;
 424
 425                 dirty = list_entry(list->next, struct dirty_root, list);
 426                 list_del_init(&dirty->list);
 427
 428                 num_bytes = btrfs_root_used(&dirty->root->root_item);
 429                 root = dirty->latest_root;
 430                 atomic_inc(&root->fs_info->throttles);
 431
 432                 mutex_lock(&root->fs_info->drop_mutex);
 433                 while(1) {
 434                         trans = btrfs_start_transaction(tree_root, 1);
 435                         ret = btrfs_drop_snapshot(trans, dirty->root);
 436                         if (ret != -EAGAIN) {
 437                                 break;
 438                         }
 439
 440                         err = btrfs_update_root(trans,
 441                                         tree_root,
 442                                         &dirty->root->root_key,
 443                                         &dirty->root->root_item);
 444                         if (err)
 445                                 ret = err;
 446                         nr = trans->blocks_used;
 447                         ret = btrfs_end_transaction_throttle(trans, tree_root);
 448                         BUG_ON(ret);
 449
 450                         mutex_unlock(&root->fs_info->drop_mutex);
 451                         btrfs_btree_balance_dirty(tree_root, nr);
 452                         cond_resched();
 453                         mutex_lock(&root->fs_info->drop_mutex);
 454                 }
 455                 BUG_ON(ret);
 456                 atomic_dec(&root->fs_info->throttles);
 457
 458                 mutex_lock(&root->fs_info->alloc_mutex);
 459                 num_bytes -= btrfs_root_used(&dirty->root->root_item);
 460                 bytes_used = btrfs_root_used(&root->root_item);
 461                 if (num_bytes) {
 462                         record_root_in_trans(root);
 463                         btrfs_set_root_used(&root->root_item,
 464                                             bytes_used - num_bytes);
 465                 }
 466                 mutex_unlock(&root->fs_info->alloc_mutex);
 467
 468                 ret = btrfs_del_root(trans, tree_root, &dirty->root->root_key);
 469                 if (ret) {
 470                         BUG();
 471                         break;
 472                 }
 473                 mutex_unlock(&root->fs_info->drop_mutex);
 474
 475                 nr = trans->blocks_used;
 476                 ret = btrfs_end_transaction(trans, tree_root);
 477                 BUG_ON(ret);
 478
 479                 free_extent_buffer(dirty->root->node);
 480                 kfree(dirty->root);
 481                 kfree(dirty);
 482
 483                 btrfs_btree_balance_dirty(tree_root, nr);
 484                 cond_resched();
 485         }
 486         return ret;
 487 }
 488
 489 int btrfs_write_ordered_inodes(struct btrfs_trans_handle *trans,
 490                                 struct btrfs_root *root)
 491 {
 492         struct btrfs_transaction *cur_trans = trans->transaction;
 493         struct inode *inode;
 494         u64 root_objectid = 0;
 495         u64 objectid = 0;
 496         int ret;
 497
 498         atomic_inc(&root->fs_info->throttles);
 499         while(1) {
 500                 ret = btrfs_find_first_ordered_inode(
 501                                 &cur_trans->ordered_inode_tree,
 502                                 &root_objectid, &objectid, &inode);
 503                 if (!ret)
 504                         break;
 505
 506                 mutex_unlock(&root->fs_info->trans_mutex);
 507
 508                 if (S_ISREG(inode->i_mode)) {
 509                         atomic_inc(&BTRFS_I(inode)->ordered_writeback);
 510                         filemap_fdatawrite(inode->i_mapping);
 511                         atomic_dec(&BTRFS_I(inode)->ordered_writeback);
 512                 }
 513                 iput(inode);
 514
 515                 mutex_lock(&root->fs_info->trans_mutex);
 516         }
 517         while(1) {
 518                 root_objectid = 0;
 519                 objectid = 0;
 520                 ret = btrfs_find_del_first_ordered_inode(
 521                                 &cur_trans->ordered_inode_tree,
 522                                 &root_objectid, &objectid, &inode);
 523                 if (!ret)
 524                         break;
 525                 mutex_unlock(&root->fs_info->trans_mutex);
 526
 527                 if (S_ISREG(inode->i_mode)) {
 528                         atomic_inc(&BTRFS_I(inode)->ordered_writeback);
 529                         filemap_write_and_wait(inode->i_mapping);
 530                         atomic_dec(&BTRFS_I(inode)->ordered_writeback);
 531                 }
 532                 atomic_dec(&inode->i_count);
 533                 iput(inode);
 534
 535                 mutex_lock(&root->fs_info->trans_mutex);
 536         }
 537         atomic_dec(&root->fs_info->throttles);
 538         return 0;
 539 }
 540
 541 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 542                                    struct btrfs_fs_info *fs_info,
 543                                    struct btrfs_pending_snapshot *pending)
 544 {
 545         struct btrfs_key key;
 546         struct btrfs_root_item *new_root_item;
 547         struct btrfs_root *tree_root = fs_info->tree_root;
 548         struct btrfs_root *root = pending->root;
 549         struct extent_buffer *tmp;
 550         struct extent_buffer *old;
 551         int ret;
 552         int namelen;
 553         u64 objectid;
 554
 555         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 556         if (!new_root_item) {
 557                 ret = -ENOMEM;
 558                 goto fail;
 559         }
 560         ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
 561         if (ret)
 562                 goto fail;
 563
 564         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
 565
 566         key.objectid = objectid;
 567         key.offset = 1;
 568         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 569
 570         old = btrfs_lock_root_node(root);
 571         btrfs_cow_block(trans, root, old, NULL, 0, &old);
 572
 573         btrfs_copy_root(trans, root, old, &tmp, objectid);
 574         btrfs_tree_unlock(old);
 575         free_extent_buffer(old);
 576
 577         btrfs_set_root_bytenr(new_root_item, tmp->start);
 578         btrfs_set_root_level(new_root_item, btrfs_header_level(tmp));
 579         ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
 580                                 new_root_item);
 581         btrfs_tree_unlock(tmp);
 582         free_extent_buffer(tmp);
 583         if (ret)
 584                 goto fail;
 585
 586         /*
 587          * insert the directory item
 588          */
 589         key.offset = (u64)-1;
 590         namelen = strlen(pending->name);
 591         ret = btrfs_insert_dir_item(trans, root->fs_info->tree_root,
 592                                     pending->name, namelen,
 593                                     root->fs_info->sb->s_root->d_inode->i_ino,
 594                                     &key, BTRFS_FT_DIR);
 595
 596         if (ret)
 597                 goto fail;
 598
 599         ret = btrfs_insert_inode_ref(trans, root->fs_info->tree_root,
 600                              pending->name, strlen(pending->name), objectid,
 601                              root->fs_info->sb->s_root->d_inode->i_ino);
 602
 603         /* Invalidate existing dcache entry for new snapshot. */
 604         btrfs_invalidate_dcache_root(root, pending->name, namelen);
 605
 606 fail:
 607         kfree(new_root_item);
 608         return ret;
 609 }
 610
 611 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
 612                                              struct btrfs_fs_info *fs_info)
 613 {
 614         struct btrfs_pending_snapshot *pending;
 615         struct list_head *head = &trans->transaction->pending_snapshots;
 616         int ret;
 617
 618         while(!list_empty(head)) {
 619                 pending = list_entry(head->next,
 620                                      struct btrfs_pending_snapshot, list);
 621                 ret = create_pending_snapshot(trans, fs_info, pending);
 622                 BUG_ON(ret);
 623                 list_del(&pending->list);
 624                 kfree(pending->name);
 625                 kfree(pending);
 626         }
 627         return 0;
 628 }
 629
 630 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 631                              struct btrfs_root *root)
 632 {
 633         unsigned long joined = 0;
 634         unsigned long timeout = 1;
 635         struct btrfs_transaction *cur_trans;
 636         struct btrfs_transaction *prev_trans = NULL;
 637         struct btrfs_root *chunk_root = root->fs_info->chunk_root;
 638         struct list_head dirty_fs_roots;
 639         struct extent_io_tree *pinned_copy;
 640         DEFINE_WAIT(wait);
 641         int ret;
 642
 643         INIT_LIST_HEAD(&dirty_fs_roots);
 644
 645         mutex_lock(&root->fs_info->trans_mutex);
 646         if (trans->transaction->in_commit) {
 647                 cur_trans = trans->transaction;
 648                 trans->transaction->use_count++;
 649                 mutex_unlock(&root->fs_info->trans_mutex);
 650                 btrfs_end_transaction(trans, root);
 651
 652                 ret = wait_for_commit(root, cur_trans);
 653                 BUG_ON(ret);
 654
 655                 mutex_lock(&root->fs_info->trans_mutex);
 656                 put_transaction(cur_trans);
 657                 mutex_unlock(&root->fs_info->trans_mutex);
 658
 659                 return 0;
 660         }
 661
 662         pinned_copy = kmalloc(sizeof(*pinned_copy), GFP_NOFS);
 663         if (!pinned_copy)
 664                 return -ENOMEM;
 665
 666         extent_io_tree_init(pinned_copy,
 667                              root->fs_info->btree_inode->i_mapping, GFP_NOFS);
 668
 669         trans->transaction->in_commit = 1;
 670         cur_trans = trans->transaction;
 671         if (cur_trans->list.prev != &root->fs_info->trans_list) {
 672                 prev_trans = list_entry(cur_trans->list.prev,
 673                                         struct btrfs_transaction, list);
 674                 if (!prev_trans->commit_done) {
 675                         prev_trans->use_count++;
 676                         mutex_unlock(&root->fs_info->trans_mutex);
 677
 678                         wait_for_commit(root, prev_trans);
 679
 680                         mutex_lock(&root->fs_info->trans_mutex);
 681                         put_transaction(prev_trans);
 682                 }
 683         }
 684
 685         do {
 686                 joined = cur_trans->num_joined;
 687                 WARN_ON(cur_trans != trans->transaction);
 688                 prepare_to_wait(&cur_trans->writer_wait, &wait,
 689                                 TASK_UNINTERRUPTIBLE);
 690
 691                 if (cur_trans->num_writers > 1)
 692                         timeout = MAX_SCHEDULE_TIMEOUT;
 693                 else
 694                         timeout = 1;
 695
 696                 mutex_unlock(&root->fs_info->trans_mutex);
 697
 698                 schedule_timeout(timeout);
 699
 700                 mutex_lock(&root->fs_info->trans_mutex);
 701                 finish_wait(&cur_trans->writer_wait, &wait);
 702                 ret = btrfs_write_ordered_inodes(trans, root);
 703
 704         } while (cur_trans->num_writers > 1 ||
 705                  (cur_trans->num_joined != joined));
 706
 707         ret = create_pending_snapshots(trans, root->fs_info);
 708         BUG_ON(ret);
 709
 710         WARN_ON(cur_trans != trans->transaction);
 711
 712         ret = add_dirty_roots(trans, &root->fs_info->fs_roots_radix,
 713                               &dirty_fs_roots);
 714         BUG_ON(ret);
 715
 716         ret = btrfs_commit_tree_roots(trans, root);
 717         BUG_ON(ret);
 718
 719         cur_trans = root->fs_info->running_transaction;
 720         spin_lock(&root->fs_info->new_trans_lock);
 721         root->fs_info->running_transaction = NULL;
 722         spin_unlock(&root->fs_info->new_trans_lock);
 723         btrfs_set_super_generation(&root->fs_info->super_copy,
 724                                    cur_trans->transid);
 725         btrfs_set_super_root(&root->fs_info->super_copy,
 726                              root->fs_info->tree_root->node->start);
 727         btrfs_set_super_root_level(&root->fs_info->super_copy,
 728                            btrfs_header_level(root->fs_info->tree_root->node));
 729
 730         btrfs_set_super_chunk_root(&root->fs_info->super_copy,
 731                                    chunk_root->node->start);
 732         btrfs_set_super_chunk_root_level(&root->fs_info->super_copy,
 733                                          btrfs_header_level(chunk_root->node));
 734         memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
 735                sizeof(root->fs_info->super_copy));
 736
 737         btrfs_copy_pinned(root, pinned_copy);
 738
 739         mutex_unlock(&root->fs_info->trans_mutex);
 740         ret = btrfs_write_and_wait_transaction(trans, root);
 741         BUG_ON(ret);
 742         write_ctree_super(trans, root);
 743
 744         btrfs_finish_extent_commit(trans, root, pinned_copy);
 745         mutex_lock(&root->fs_info->trans_mutex);
 746
 747         kfree(pinned_copy);
 748
 749         cur_trans->commit_done = 1;
 750         root->fs_info->last_trans_committed = cur_trans->transid;
 751         wake_up(&cur_trans->commit_wait);
 752         put_transaction(cur_trans);
 753         put_transaction(cur_trans);
 754
 755         if (root->fs_info->closing)
 756                 list_splice_init(&root->fs_info->dead_roots, &dirty_fs_roots);
 757         else
 758                 list_splice_init(&dirty_fs_roots, &root->fs_info->dead_roots);
 759
 760         mutex_unlock(&root->fs_info->trans_mutex);
 761         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 762
 763         if (root->fs_info->closing) {
 764                 drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
 765         }
 766         return ret;
 767 }
 768
 769 int btrfs_clean_old_snapshots(struct btrfs_root *root)
 770 {
 771         struct list_head dirty_roots;
 772         INIT_LIST_HEAD(&dirty_roots);
 773 again:
 774         mutex_lock(&root->fs_info->trans_mutex);
 775         list_splice_init(&root->fs_info->dead_roots, &dirty_roots);
 776         mutex_unlock(&root->fs_info->trans_mutex);
 777
 778         if (!list_empty(&dirty_roots)) {
 779                 drop_dirty_roots(root, &dirty_roots);
 780                 goto again;
 781         }
 782         return 0;
 783 }
 784