fs/btrfs/transaction.c

   1 /*
   2  * Copyright (C) 2007 Oracle.  All rights reserved.
   3  *
   4  * This program is free software; you can redistribute it and/or
   5  * modify it under the terms of the GNU General Public
   6  * License v2 as published by the Free Software Foundation.
   7  *
   8  * This program is distributed in the hope that it will be useful,
   9  * but WITHOUT ANY WARRANTY; without even the implied warranty of
  10  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
  11  * General Public License for more details.
  12  *
  13  * You should have received a copy of the GNU General Public
  14  * License along with this program; if not, write to the
  15  * Free Software Foundation, Inc., 59 Temple Place - Suite 330,
  16  * Boston, MA 021110-1307, USA.
  17  */
  18
  19 #include <linux/fs.h>
  20 #include <linux/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                 extent_io_tree_init(&cur_trans->dirty_pages,
  71                                      root->fs_info->btree_inode->i_mapping,
  72                                      GFP_NOFS);
  73                 spin_lock(&root->fs_info->new_trans_lock);
  74                 root->fs_info->running_transaction = cur_trans;
  75                 spin_unlock(&root->fs_info->new_trans_lock);
  76         } else {
  77                 cur_trans->num_writers++;
  78                 cur_trans->num_joined++;
  79         }
  80
  81         return 0;
  82 }
  83
  84 static noinline int record_root_in_trans(struct btrfs_root *root)
  85 {
  86         u64 running_trans_id = root->fs_info->running_transaction->transid;
  87         if (root->ref_cows && root->last_trans < running_trans_id) {
  88                 WARN_ON(root == root->fs_info->extent_root);
  89                 if (root->root_item.refs != 0) {
  90                         radix_tree_tag_set(&root->fs_info->fs_roots_radix,
  91                                    (unsigned long)root->root_key.objectid,
  92                                    BTRFS_ROOT_TRANS_TAG);
  93                         root->commit_root = btrfs_root_node(root);
  94                 } else {
  95                         WARN_ON(1);
  96                 }
  97                 root->last_trans = running_trans_id;
  98         }
  99         return 0;
 100 }
 101
 102 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 103                                                    int num_blocks)
 104 {
 105         struct btrfs_trans_handle *h =
 106                 kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 107         int ret;
 108
 109         mutex_lock(&root->fs_info->trans_mutex);
 110         ret = join_transaction(root);
 111         BUG_ON(ret);
 112
 113         record_root_in_trans(root);
 114         h->transid = root->fs_info->running_transaction->transid;
 115         h->transaction = root->fs_info->running_transaction;
 116         h->blocks_reserved = num_blocks;
 117         h->blocks_used = 0;
 118         h->block_group = NULL;
 119         h->alloc_exclude_nr = 0;
 120         h->alloc_exclude_start = 0;
 121         root->fs_info->running_transaction->use_count++;
 122         mutex_unlock(&root->fs_info->trans_mutex);
 123         return h;
 124 }
 125
 126 static noinline int wait_for_commit(struct btrfs_root *root,
 127                                     struct btrfs_transaction *commit)
 128 {
 129         DEFINE_WAIT(wait);
 130         mutex_lock(&root->fs_info->trans_mutex);
 131         while(!commit->commit_done) {
 132                 prepare_to_wait(&commit->commit_wait, &wait,
 133                                 TASK_UNINTERRUPTIBLE);
 134                 if (commit->commit_done)
 135                         break;
 136                 mutex_unlock(&root->fs_info->trans_mutex);
 137                 schedule();
 138                 mutex_lock(&root->fs_info->trans_mutex);
 139         }
 140         mutex_unlock(&root->fs_info->trans_mutex);
 141         finish_wait(&commit->commit_wait, &wait);
 142         return 0;
 143 }
 144
 145 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 146                           struct btrfs_root *root, int throttle)
 147 {
 148         struct btrfs_transaction *cur_trans;
 149
 150         mutex_lock(&root->fs_info->trans_mutex);
 151         cur_trans = root->fs_info->running_transaction;
 152         WARN_ON(cur_trans != trans->transaction);
 153         WARN_ON(cur_trans->num_writers < 1);
 154         cur_trans->num_writers--;
 155
 156         if (waitqueue_active(&cur_trans->writer_wait))
 157                 wake_up(&cur_trans->writer_wait);
 158
 159         if (cur_trans->in_commit && throttle) {
 160                 DEFINE_WAIT(wait);
 161                 mutex_unlock(&root->fs_info->trans_mutex);
 162                 prepare_to_wait(&root->fs_info->transaction_throttle, &wait,
 163                                 TASK_UNINTERRUPTIBLE);
 164                 schedule();
 165                 finish_wait(&root->fs_info->transaction_throttle, &wait);
 166                 mutex_lock(&root->fs_info->trans_mutex);
 167         }
 168
 169         put_transaction(cur_trans);
 170         mutex_unlock(&root->fs_info->trans_mutex);
 171         memset(trans, 0, sizeof(*trans));
 172         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 173         return 0;
 174 }
 175
 176 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 177                           struct btrfs_root *root)
 178 {
 179         return __btrfs_end_transaction(trans, root, 0);
 180 }
 181
 182 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 183                                    struct btrfs_root *root)
 184 {
 185         return __btrfs_end_transaction(trans, root, 1);
 186 }
 187
 188
 189 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 190                                      struct btrfs_root *root)
 191 {
 192         int ret;
 193         int err;
 194         int werr = 0;
 195         struct extent_io_tree *dirty_pages;
 196         struct page *page;
 197         struct inode *btree_inode = root->fs_info->btree_inode;
 198         u64 start;
 199         u64 end;
 200         unsigned long index;
 201
 202         if (!trans || !trans->transaction) {
 203                 return filemap_write_and_wait(btree_inode->i_mapping);
 204         }
 205         dirty_pages = &trans->transaction->dirty_pages;
 206         while(1) {
 207                 ret = find_first_extent_bit(dirty_pages, 0, &start, &end,
 208                                             EXTENT_DIRTY);
 209                 if (ret)
 210                         break;
 211                 clear_extent_dirty(dirty_pages, start, end, GFP_NOFS);
 212                 while(start <= end) {
 213                         index = start >> PAGE_CACHE_SHIFT;
 214                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 215                         page = find_lock_page(btree_inode->i_mapping, index);
 216                         if (!page)
 217                                 continue;
 218                         if (PageWriteback(page)) {
 219                                 if (PageDirty(page))
 220                                         wait_on_page_writeback(page);
 221                                 else {
 222                                         unlock_page(page);
 223                                         page_cache_release(page);
 224                                         continue;
 225                                 }
 226                         }
 227                         err = write_one_page(page, 0);
 228                         if (err)
 229                                 werr = err;
 230                         page_cache_release(page);
 231                 }
 232         }
 233         err = filemap_fdatawait(btree_inode->i_mapping);
 234         if (err)
 235                 werr = err;
 236         return werr;
 237 }
 238
 239 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 240                                struct btrfs_root *root)
 241 {
 242         int ret;
 243         u64 old_root_bytenr;
 244         struct btrfs_root *tree_root = root->fs_info->tree_root;
 245
 246         btrfs_write_dirty_block_groups(trans, root);
 247         while(1) {
 248                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 249                 if (old_root_bytenr == root->node->start)
 250                         break;
 251                 btrfs_set_root_bytenr(&root->root_item,
 252                                        root->node->start);
 253                 btrfs_set_root_level(&root->root_item,
 254                                      btrfs_header_level(root->node));
 255                 ret = btrfs_update_root(trans, tree_root,
 256                                         &root->root_key,
 257                                         &root->root_item);
 258                 BUG_ON(ret);
 259                 btrfs_write_dirty_block_groups(trans, root);
 260         }
 261         return 0;
 262 }
 263
 264 int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
 265                             struct btrfs_root *root)
 266 {
 267         struct btrfs_fs_info *fs_info = root->fs_info;
 268         struct list_head *next;
 269
 270         while(!list_empty(&fs_info->dirty_cowonly_roots)) {
 271                 next = fs_info->dirty_cowonly_roots.next;
 272                 list_del_init(next);
 273                 root = list_entry(next, struct btrfs_root, dirty_list);
 274                 update_cowonly_root(trans, root);
 275         }
 276         return 0;
 277 }
 278
 279 struct dirty_root {
 280         struct list_head list;
 281         struct btrfs_root *root;
 282         struct btrfs_root *latest_root;
 283 };
 284
 285 int btrfs_add_dead_root(struct btrfs_root *root,
 286                         struct btrfs_root *latest,
 287                         struct list_head *dead_list)
 288 {
 289         struct dirty_root *dirty;
 290
 291         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 292         if (!dirty)
 293                 return -ENOMEM;
 294         dirty->root = root;
 295         dirty->latest_root = latest;
 296         list_add(&dirty->list, dead_list);
 297         return 0;
 298 }
 299
 300 static noinline int add_dirty_roots(struct btrfs_trans_handle *trans,
 301                                     struct radix_tree_root *radix,
 302                                     struct list_head *list)
 303 {
 304         struct dirty_root *dirty;
 305         struct btrfs_root *gang[8];
 306         struct btrfs_root *root;
 307         int i;
 308         int ret;
 309         int err = 0;
 310         u32 refs;
 311
 312         while(1) {
 313                 ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
 314                                                  ARRAY_SIZE(gang),
 315                                                  BTRFS_ROOT_TRANS_TAG);
 316                 if (ret == 0)
 317                         break;
 318                 for (i = 0; i < ret; i++) {
 319                         root = gang[i];
 320                         radix_tree_tag_clear(radix,
 321                                      (unsigned long)root->root_key.objectid,
 322                                      BTRFS_ROOT_TRANS_TAG);
 323                         if (root->commit_root == root->node) {
 324                                 WARN_ON(root->node->start !=
 325                                         btrfs_root_bytenr(&root->root_item));
 326                                 free_extent_buffer(root->commit_root);
 327                                 root->commit_root = NULL;
 328
 329                                 /* make sure to update the root on disk
 330                                  * so we get any updates to the block used
 331                                  * counts
 332                                  */
 333                                 err = btrfs_update_root(trans,
 334                                                 root->fs_info->tree_root,
 335                                                 &root->root_key,
 336                                                 &root->root_item);
 337                                 continue;
 338                         }
 339                         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 340                         BUG_ON(!dirty);
 341                         dirty->root = kmalloc(sizeof(*dirty->root), GFP_NOFS);
 342                         BUG_ON(!dirty->root);
 343
 344                         memset(&root->root_item.drop_progress, 0,
 345                                sizeof(struct btrfs_disk_key));
 346                         root->root_item.drop_level = 0;
 347
 348                         memcpy(dirty->root, root, sizeof(*root));
 349                         dirty->root->node = root->commit_root;
 350                         dirty->latest_root = root;
 351                         root->commit_root = NULL;
 352
 353                         root->root_key.offset = root->fs_info->generation;
 354                         btrfs_set_root_bytenr(&root->root_item,
 355                                               root->node->start);
 356                         btrfs_set_root_level(&root->root_item,
 357                                              btrfs_header_level(root->node));
 358                         err = btrfs_insert_root(trans, root->fs_info->tree_root,
 359                                                 &root->root_key,
 360                                                 &root->root_item);
 361                         if (err)
 362                                 break;
 363
 364                         refs = btrfs_root_refs(&dirty->root->root_item);
 365                         btrfs_set_root_refs(&dirty->root->root_item, refs - 1);
 366                         err = btrfs_update_root(trans, root->fs_info->tree_root,
 367                                                 &dirty->root->root_key,
 368                                                 &dirty->root->root_item);
 369
 370                         BUG_ON(err);
 371                         if (refs == 1) {
 372                                 list_add(&dirty->list, list);
 373                         } else {
 374                                 WARN_ON(1);
 375                                 kfree(dirty->root);
 376                                 kfree(dirty);
 377                         }
 378                 }
 379         }
 380         return err;
 381 }
 382
 383 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 384 {
 385         struct btrfs_fs_info *info = root->fs_info;
 386         int ret;
 387         struct btrfs_trans_handle *trans;
 388         unsigned long nr;
 389
 390         smp_mb();
 391         if (root->defrag_running)
 392                 return 0;
 393         trans = btrfs_start_transaction(root, 1);
 394         while (1) {
 395                 root->defrag_running = 1;
 396                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 397                 nr = trans->blocks_used;
 398                 btrfs_end_transaction(trans, root);
 399                 btrfs_btree_balance_dirty(info->tree_root, nr);
 400                 cond_resched();
 401
 402                 trans = btrfs_start_transaction(root, 1);
 403                 if (root->fs_info->closing || ret != -EAGAIN)
 404                         break;
 405         }
 406         root->defrag_running = 0;
 407         smp_mb();
 408         btrfs_end_transaction(trans, root);
 409         return 0;
 410 }
 411
 412 static noinline int drop_dirty_roots(struct btrfs_root *tree_root,
 413                                      struct list_head *list)
 414 {
 415         struct dirty_root *dirty;
 416         struct btrfs_trans_handle *trans;
 417         unsigned long nr;
 418         u64 num_bytes;
 419         u64 bytes_used;
 420         int ret = 0;
 421         int err;
 422
 423         while(!list_empty(list)) {
 424                 struct btrfs_root *root;
 425
 426                 dirty = list_entry(list->next, struct dirty_root, list);
 427                 list_del_init(&dirty->list);
 428
 429                 num_bytes = btrfs_root_used(&dirty->root->root_item);
 430                 root = dirty->latest_root;
 431                 atomic_inc(&root->fs_info->throttles);
 432
 433                 mutex_lock(&root->fs_info->drop_mutex);
 434                 while(1) {
 435                         trans = btrfs_start_transaction(tree_root, 1);
 436                         ret = btrfs_drop_snapshot(trans, dirty->root);
 437                         if (ret != -EAGAIN) {
 438                                 break;
 439                         }
 440
 441                         err = btrfs_update_root(trans,
 442                                         tree_root,
 443                                         &dirty->root->root_key,
 444                                         &dirty->root->root_item);
 445                         if (err)
 446                                 ret = err;
 447                         nr = trans->blocks_used;
 448                         ret = btrfs_end_transaction_throttle(trans, tree_root);
 449                         BUG_ON(ret);
 450
 451                         mutex_unlock(&root->fs_info->drop_mutex);
 452                         btrfs_btree_balance_dirty(tree_root, nr);
 453                         cond_resched();
 454                         mutex_lock(&root->fs_info->drop_mutex);
 455                 }
 456                 BUG_ON(ret);
 457                 atomic_dec(&root->fs_info->throttles);
 458
 459                 mutex_lock(&root->fs_info->alloc_mutex);
 460                 num_bytes -= btrfs_root_used(&dirty->root->root_item);
 461                 bytes_used = btrfs_root_used(&root->root_item);
 462                 if (num_bytes) {
 463                         record_root_in_trans(root);
 464                         btrfs_set_root_used(&root->root_item,
 465                                             bytes_used - num_bytes);
 466                 }
 467                 mutex_unlock(&root->fs_info->alloc_mutex);
 468
 469                 ret = btrfs_del_root(trans, tree_root, &dirty->root->root_key);
 470                 if (ret) {
 471                         BUG();
 472                         break;
 473                 }
 474                 mutex_unlock(&root->fs_info->drop_mutex);
 475
 476                 nr = trans->blocks_used;
 477                 ret = btrfs_end_transaction(trans, tree_root);
 478                 BUG_ON(ret);
 479
 480                 free_extent_buffer(dirty->root->node);
 481                 kfree(dirty->root);
 482                 kfree(dirty);
 483
 484                 btrfs_btree_balance_dirty(tree_root, nr);
 485                 cond_resched();
 486         }
 487         return ret;
 488 }
 489
 490 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 491                                    struct btrfs_fs_info *fs_info,
 492                                    struct btrfs_pending_snapshot *pending)
 493 {
 494         struct btrfs_key key;
 495         struct btrfs_root_item *new_root_item;
 496         struct btrfs_root *tree_root = fs_info->tree_root;
 497         struct btrfs_root *root = pending->root;
 498         struct extent_buffer *tmp;
 499         struct extent_buffer *old;
 500         int ret;
 501         int namelen;
 502         u64 objectid;
 503
 504         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 505         if (!new_root_item) {
 506                 ret = -ENOMEM;
 507                 goto fail;
 508         }
 509         ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
 510         if (ret)
 511                 goto fail;
 512
 513         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
 514
 515         key.objectid = objectid;
 516         key.offset = 1;
 517         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 518
 519         old = btrfs_lock_root_node(root);
 520         btrfs_cow_block(trans, root, old, NULL, 0, &old);
 521
 522         btrfs_copy_root(trans, root, old, &tmp, objectid);
 523         btrfs_tree_unlock(old);
 524         free_extent_buffer(old);
 525
 526         btrfs_set_root_bytenr(new_root_item, tmp->start);
 527         btrfs_set_root_level(new_root_item, btrfs_header_level(tmp));
 528         ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
 529                                 new_root_item);
 530         btrfs_tree_unlock(tmp);
 531         free_extent_buffer(tmp);
 532         if (ret)
 533                 goto fail;
 534
 535         /*
 536          * insert the directory item
 537          */
 538         key.offset = (u64)-1;
 539         namelen = strlen(pending->name);
 540         ret = btrfs_insert_dir_item(trans, root->fs_info->tree_root,
 541                                     pending->name, namelen,
 542                                     root->fs_info->sb->s_root->d_inode->i_ino,
 543                                     &key, BTRFS_FT_DIR);
 544
 545         if (ret)
 546                 goto fail;
 547
 548         ret = btrfs_insert_inode_ref(trans, root->fs_info->tree_root,
 549                              pending->name, strlen(pending->name), objectid,
 550                              root->fs_info->sb->s_root->d_inode->i_ino);
 551
 552         /* Invalidate existing dcache entry for new snapshot. */
 553         btrfs_invalidate_dcache_root(root, pending->name, namelen);
 554
 555 fail:
 556         kfree(new_root_item);
 557         return ret;
 558 }
 559
 560 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
 561                                              struct btrfs_fs_info *fs_info)
 562 {
 563         struct btrfs_pending_snapshot *pending;
 564         struct list_head *head = &trans->transaction->pending_snapshots;
 565         int ret;
 566
 567         while(!list_empty(head)) {
 568                 pending = list_entry(head->next,
 569                                      struct btrfs_pending_snapshot, list);
 570                 ret = create_pending_snapshot(trans, fs_info, pending);
 571                 BUG_ON(ret);
 572                 list_del(&pending->list);
 573                 kfree(pending->name);
 574                 kfree(pending);
 575         }
 576         return 0;
 577 }
 578
 579 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 580                              struct btrfs_root *root)
 581 {
 582         unsigned long joined = 0;
 583         unsigned long timeout = 1;
 584         struct btrfs_transaction *cur_trans;
 585         struct btrfs_transaction *prev_trans = NULL;
 586         struct btrfs_root *chunk_root = root->fs_info->chunk_root;
 587         struct list_head dirty_fs_roots;
 588         struct extent_io_tree *pinned_copy;
 589         DEFINE_WAIT(wait);
 590         int ret;
 591
 592         INIT_LIST_HEAD(&dirty_fs_roots);
 593
 594         mutex_lock(&root->fs_info->trans_mutex);
 595         if (trans->transaction->in_commit) {
 596                 cur_trans = trans->transaction;
 597                 trans->transaction->use_count++;
 598                 mutex_unlock(&root->fs_info->trans_mutex);
 599                 btrfs_end_transaction(trans, root);
 600
 601                 ret = wait_for_commit(root, cur_trans);
 602                 BUG_ON(ret);
 603
 604                 mutex_lock(&root->fs_info->trans_mutex);
 605                 put_transaction(cur_trans);
 606                 mutex_unlock(&root->fs_info->trans_mutex);
 607
 608                 return 0;
 609         }
 610
 611         pinned_copy = kmalloc(sizeof(*pinned_copy), GFP_NOFS);
 612         if (!pinned_copy)
 613                 return -ENOMEM;
 614
 615         extent_io_tree_init(pinned_copy,
 616                              root->fs_info->btree_inode->i_mapping, GFP_NOFS);
 617
 618 printk("commit trans %Lu\n", trans->transid);
 619         trans->transaction->in_commit = 1;
 620         cur_trans = trans->transaction;
 621         if (cur_trans->list.prev != &root->fs_info->trans_list) {
 622                 prev_trans = list_entry(cur_trans->list.prev,
 623                                         struct btrfs_transaction, list);
 624                 if (!prev_trans->commit_done) {
 625                         prev_trans->use_count++;
 626                         mutex_unlock(&root->fs_info->trans_mutex);
 627
 628                         wait_for_commit(root, prev_trans);
 629
 630                         mutex_lock(&root->fs_info->trans_mutex);
 631                         put_transaction(prev_trans);
 632                 }
 633         }
 634
 635         do {
 636                 joined = cur_trans->num_joined;
 637                 WARN_ON(cur_trans != trans->transaction);
 638                 prepare_to_wait(&cur_trans->writer_wait, &wait,
 639                                 TASK_UNINTERRUPTIBLE);
 640
 641                 if (cur_trans->num_writers > 1)
 642                         timeout = MAX_SCHEDULE_TIMEOUT;
 643                 else
 644                         timeout = 1;
 645
 646                 mutex_unlock(&root->fs_info->trans_mutex);
 647
 648                 schedule_timeout(timeout);
 649
 650                 mutex_lock(&root->fs_info->trans_mutex);
 651                 finish_wait(&cur_trans->writer_wait, &wait);
 652         } while (cur_trans->num_writers > 1 ||
 653                  (cur_trans->num_joined != joined));
 654
 655         ret = create_pending_snapshots(trans, root->fs_info);
 656         BUG_ON(ret);
 657
 658         WARN_ON(cur_trans != trans->transaction);
 659
 660         ret = add_dirty_roots(trans, &root->fs_info->fs_roots_radix,
 661                               &dirty_fs_roots);
 662         BUG_ON(ret);
 663
 664         ret = btrfs_commit_tree_roots(trans, root);
 665         BUG_ON(ret);
 666
 667         cur_trans = root->fs_info->running_transaction;
 668         spin_lock(&root->fs_info->new_trans_lock);
 669         root->fs_info->running_transaction = NULL;
 670         spin_unlock(&root->fs_info->new_trans_lock);
 671         btrfs_set_super_generation(&root->fs_info->super_copy,
 672                                    cur_trans->transid);
 673         btrfs_set_super_root(&root->fs_info->super_copy,
 674                              root->fs_info->tree_root->node->start);
 675         btrfs_set_super_root_level(&root->fs_info->super_copy,
 676                            btrfs_header_level(root->fs_info->tree_root->node));
 677
 678         btrfs_set_super_chunk_root(&root->fs_info->super_copy,
 679                                    chunk_root->node->start);
 680         btrfs_set_super_chunk_root_level(&root->fs_info->super_copy,
 681                                          btrfs_header_level(chunk_root->node));
 682         memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
 683                sizeof(root->fs_info->super_copy));
 684
 685         btrfs_copy_pinned(root, pinned_copy);
 686
 687         wake_up(&root->fs_info->transaction_throttle);
 688
 689         mutex_unlock(&root->fs_info->trans_mutex);
 690         ret = btrfs_write_and_wait_transaction(trans, root);
 691         BUG_ON(ret);
 692         write_ctree_super(trans, root);
 693
 694         btrfs_finish_extent_commit(trans, root, pinned_copy);
 695         mutex_lock(&root->fs_info->trans_mutex);
 696
 697         kfree(pinned_copy);
 698
 699         cur_trans->commit_done = 1;
 700         root->fs_info->last_trans_committed = cur_trans->transid;
 701         wake_up(&cur_trans->commit_wait);
 702         put_transaction(cur_trans);
 703         put_transaction(cur_trans);
 704
 705         if (root->fs_info->closing)
 706                 list_splice_init(&root->fs_info->dead_roots, &dirty_fs_roots);
 707         else
 708                 list_splice_init(&dirty_fs_roots, &root->fs_info->dead_roots);
 709
 710         mutex_unlock(&root->fs_info->trans_mutex);
 711 printk("done commit trans %Lu\n", trans->transid);
 712         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 713
 714         if (root->fs_info->closing) {
 715                 drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
 716         }
 717         return ret;
 718 }
 719
 720 int btrfs_clean_old_snapshots(struct btrfs_root *root)
 721 {
 722         struct list_head dirty_roots;
 723         INIT_LIST_HEAD(&dirty_roots);
 724 again:
 725         mutex_lock(&root->fs_info->trans_mutex);
 726         list_splice_init(&root->fs_info->dead_roots, &dirty_roots);
 727         mutex_unlock(&root->fs_info->trans_mutex);
 728
 729         if (!list_empty(&dirty_roots)) {
 730                 drop_dirty_roots(root, &dirty_roots);
 731                 goto again;
 732         }
 733         return 0;
 734 }
 735