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 #include "ref-cache.h"
  28
  29 static int total_trans = 0;
  30 extern struct kmem_cache *btrfs_trans_handle_cachep;
  31 extern struct kmem_cache *btrfs_transaction_cachep;
  32
  33 #define BTRFS_ROOT_TRANS_TAG 0
  34
  35 static noinline 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 noinline 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->last_alloc = 0;
  59                 root->fs_info->last_data_alloc = 0;
  60                 cur_trans->num_writers = 1;
  61                 cur_trans->num_joined = 0;
  62                 cur_trans->transid = root->fs_info->generation;
  63                 init_waitqueue_head(&cur_trans->writer_wait);
  64                 init_waitqueue_head(&cur_trans->commit_wait);
  65                 cur_trans->in_commit = 0;
  66                 cur_trans->blocked = 0;
  67                 cur_trans->use_count = 1;
  68                 cur_trans->commit_done = 0;
  69                 cur_trans->start_time = get_seconds();
  70                 INIT_LIST_HEAD(&cur_trans->pending_snapshots);
  71                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
  72                 extent_io_tree_init(&cur_trans->dirty_pages,
  73                                      root->fs_info->btree_inode->i_mapping,
  74                                      GFP_NOFS);
  75                 spin_lock(&root->fs_info->new_trans_lock);
  76                 root->fs_info->running_transaction = cur_trans;
  77                 spin_unlock(&root->fs_info->new_trans_lock);
  78         } else {
  79                 cur_trans->num_writers++;
  80                 cur_trans->num_joined++;
  81         }
  82
  83         return 0;
  84 }
  85
  86 static noinline int record_root_in_trans(struct btrfs_root *root)
  87 {
  88         struct btrfs_dirty_root *dirty;
  89         u64 running_trans_id = root->fs_info->running_transaction->transid;
  90         if (root->ref_cows && root->last_trans < running_trans_id) {
  91                 WARN_ON(root == root->fs_info->extent_root);
  92                 if (root->root_item.refs != 0) {
  93                         radix_tree_tag_set(&root->fs_info->fs_roots_radix,
  94                                    (unsigned long)root->root_key.objectid,
  95                                    BTRFS_ROOT_TRANS_TAG);
  96
  97                         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
  98                         BUG_ON(!dirty);
  99                         dirty->root = kmalloc(sizeof(*dirty->root), GFP_NOFS);
 100                         BUG_ON(!dirty->root);
 101                         dirty->latest_root = root;
 102                         INIT_LIST_HEAD(&dirty->list);
 103
 104                         root->commit_root = btrfs_root_node(root);
 105
 106                         memcpy(dirty->root, root, sizeof(*root));
 107                         spin_lock_init(&dirty->root->node_lock);
 108                         spin_lock_init(&dirty->root->list_lock);
 109                         mutex_init(&dirty->root->objectid_mutex);
 110                         INIT_LIST_HEAD(&dirty->root->dead_list);
 111                         dirty->root->node = root->commit_root;
 112                         dirty->root->commit_root = NULL;
 113
 114                         spin_lock(&root->list_lock);
 115                         list_add(&dirty->root->dead_list, &root->dead_list);
 116                         spin_unlock(&root->list_lock);
 117
 118                         root->dirty_root = dirty;
 119                 } else {
 120                         WARN_ON(1);
 121                 }
 122                 root->last_trans = running_trans_id;
 123         }
 124         return 0;
 125 }
 126
 127 static void wait_current_trans(struct btrfs_root *root)
 128 {
 129         struct btrfs_transaction *cur_trans;
 130
 131         cur_trans = root->fs_info->running_transaction;
 132         if (cur_trans && cur_trans->blocked) {
 133                 DEFINE_WAIT(wait);
 134                 cur_trans->use_count++;
 135                 while(1) {
 136                         prepare_to_wait(&root->fs_info->transaction_wait, &wait,
 137                                         TASK_UNINTERRUPTIBLE);
 138                         if (cur_trans->blocked) {
 139                                 mutex_unlock(&root->fs_info->trans_mutex);
 140                                 schedule();
 141                                 mutex_lock(&root->fs_info->trans_mutex);
 142                                 finish_wait(&root->fs_info->transaction_wait,
 143                                             &wait);
 144                         } else {
 145                                 finish_wait(&root->fs_info->transaction_wait,
 146                                             &wait);
 147                                 break;
 148                         }
 149                 }
 150                 put_transaction(cur_trans);
 151         }
 152 }
 153
 154 struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 155                                              int num_blocks, int join)
 156 {
 157         struct btrfs_trans_handle *h =
 158                 kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 159         int ret;
 160
 161         mutex_lock(&root->fs_info->trans_mutex);
 162         if (!join)
 163                 wait_current_trans(root);
 164         ret = join_transaction(root);
 165         BUG_ON(ret);
 166
 167         record_root_in_trans(root);
 168         h->transid = root->fs_info->running_transaction->transid;
 169         h->transaction = root->fs_info->running_transaction;
 170         h->blocks_reserved = num_blocks;
 171         h->blocks_used = 0;
 172         h->block_group = NULL;
 173         h->alloc_exclude_nr = 0;
 174         h->alloc_exclude_start = 0;
 175         root->fs_info->running_transaction->use_count++;
 176         mutex_unlock(&root->fs_info->trans_mutex);
 177         return h;
 178 }
 179
 180 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 181                                                    int num_blocks)
 182 {
 183         return start_transaction(root, num_blocks, 0);
 184 }
 185 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root,
 186                                                    int num_blocks)
 187 {
 188         return start_transaction(root, num_blocks, 1);
 189 }
 190
 191 static noinline int wait_for_commit(struct btrfs_root *root,
 192                                     struct btrfs_transaction *commit)
 193 {
 194         DEFINE_WAIT(wait);
 195         mutex_lock(&root->fs_info->trans_mutex);
 196         while(!commit->commit_done) {
 197                 prepare_to_wait(&commit->commit_wait, &wait,
 198                                 TASK_UNINTERRUPTIBLE);
 199                 if (commit->commit_done)
 200                         break;
 201                 mutex_unlock(&root->fs_info->trans_mutex);
 202                 schedule();
 203                 mutex_lock(&root->fs_info->trans_mutex);
 204         }
 205         mutex_unlock(&root->fs_info->trans_mutex);
 206         finish_wait(&commit->commit_wait, &wait);
 207         return 0;
 208 }
 209
 210 static void throttle_on_drops(struct btrfs_root *root)
 211 {
 212         struct btrfs_fs_info *info = root->fs_info;
 213         int harder_count = 0;
 214
 215 harder:
 216         if (atomic_read(&info->throttles)) {
 217                 DEFINE_WAIT(wait);
 218                 int thr;
 219                 thr = atomic_read(&info->throttle_gen);
 220
 221                 do {
 222                         prepare_to_wait(&info->transaction_throttle,
 223                                         &wait, TASK_UNINTERRUPTIBLE);
 224                         if (!atomic_read(&info->throttles)) {
 225                                 finish_wait(&info->transaction_throttle, &wait);
 226                                 break;
 227                         }
 228                         schedule();
 229                         finish_wait(&info->transaction_throttle, &wait);
 230                 } while (thr == atomic_read(&info->throttle_gen));
 231                 harder_count++;
 232
 233                 if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
 234                     harder_count < 2)
 235                         goto harder;
 236
 237                 if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
 238                     harder_count < 10)
 239                         goto harder;
 240
 241                 if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
 242                     harder_count < 20)
 243                         goto harder;
 244         }
 245 }
 246
 247 void btrfs_throttle(struct btrfs_root *root)
 248 {
 249         mutex_lock(&root->fs_info->trans_mutex);
 250         wait_current_trans(root);
 251         mutex_unlock(&root->fs_info->trans_mutex);
 252
 253         throttle_on_drops(root);
 254 }
 255
 256 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 257                           struct btrfs_root *root, int throttle)
 258 {
 259         struct btrfs_transaction *cur_trans;
 260         struct btrfs_fs_info *info = root->fs_info;
 261
 262         mutex_lock(&info->trans_mutex);
 263         cur_trans = info->running_transaction;
 264         WARN_ON(cur_trans != trans->transaction);
 265         WARN_ON(cur_trans->num_writers < 1);
 266         cur_trans->num_writers--;
 267
 268         if (waitqueue_active(&cur_trans->writer_wait))
 269                 wake_up(&cur_trans->writer_wait);
 270         put_transaction(cur_trans);
 271         mutex_unlock(&info->trans_mutex);
 272         memset(trans, 0, sizeof(*trans));
 273         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 274
 275         if (throttle)
 276                 throttle_on_drops(root);
 277
 278         return 0;
 279 }
 280
 281 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 282                           struct btrfs_root *root)
 283 {
 284         return __btrfs_end_transaction(trans, root, 0);
 285 }
 286
 287 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 288                                    struct btrfs_root *root)
 289 {
 290         return __btrfs_end_transaction(trans, root, 1);
 291 }
 292
 293
 294 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 295                                      struct btrfs_root *root)
 296 {
 297         int ret;
 298         int err;
 299         int werr = 0;
 300         struct extent_io_tree *dirty_pages;
 301         struct page *page;
 302         struct inode *btree_inode = root->fs_info->btree_inode;
 303         u64 start;
 304         u64 end;
 305         unsigned long index;
 306
 307         if (!trans || !trans->transaction) {
 308                 return filemap_write_and_wait(btree_inode->i_mapping);
 309         }
 310         dirty_pages = &trans->transaction->dirty_pages;
 311         while(1) {
 312                 ret = find_first_extent_bit(dirty_pages, 0, &start, &end,
 313                                             EXTENT_DIRTY);
 314                 if (ret)
 315                         break;
 316                 clear_extent_dirty(dirty_pages, start, end, GFP_NOFS);
 317                 while(start <= end) {
 318                         index = start >> PAGE_CACHE_SHIFT;
 319                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 320                         page = find_lock_page(btree_inode->i_mapping, index);
 321                         if (!page)
 322                                 continue;
 323                         if (PageWriteback(page)) {
 324                                 if (PageDirty(page))
 325                                         wait_on_page_writeback(page);
 326                                 else {
 327                                         unlock_page(page);
 328                                         page_cache_release(page);
 329                                         continue;
 330                                 }
 331                         }
 332                         err = write_one_page(page, 0);
 333                         if (err)
 334                                 werr = err;
 335                         page_cache_release(page);
 336                 }
 337         }
 338         err = filemap_fdatawait(btree_inode->i_mapping);
 339         if (err)
 340                 werr = err;
 341         return werr;
 342 }
 343
 344 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 345                                struct btrfs_root *root)
 346 {
 347         int ret;
 348         u64 old_root_bytenr;
 349         struct btrfs_root *tree_root = root->fs_info->tree_root;
 350
 351         btrfs_write_dirty_block_groups(trans, root);
 352         while(1) {
 353                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 354                 if (old_root_bytenr == root->node->start)
 355                         break;
 356                 btrfs_set_root_bytenr(&root->root_item,
 357                                        root->node->start);
 358                 btrfs_set_root_level(&root->root_item,
 359                                      btrfs_header_level(root->node));
 360                 ret = btrfs_update_root(trans, tree_root,
 361                                         &root->root_key,
 362                                         &root->root_item);
 363                 BUG_ON(ret);
 364                 btrfs_write_dirty_block_groups(trans, root);
 365         }
 366         return 0;
 367 }
 368
 369 int btrfs_commit_tree_roots(struct btrfs_trans_handle *trans,
 370                             struct btrfs_root *root)
 371 {
 372         struct btrfs_fs_info *fs_info = root->fs_info;
 373         struct list_head *next;
 374
 375         while(!list_empty(&fs_info->dirty_cowonly_roots)) {
 376                 next = fs_info->dirty_cowonly_roots.next;
 377                 list_del_init(next);
 378                 root = list_entry(next, struct btrfs_root, dirty_list);
 379                 update_cowonly_root(trans, root);
 380         }
 381         return 0;
 382 }
 383
 384 int btrfs_add_dead_root(struct btrfs_root *root,
 385                         struct btrfs_root *latest,
 386                         struct list_head *dead_list)
 387 {
 388         struct btrfs_dirty_root *dirty;
 389
 390         dirty = kmalloc(sizeof(*dirty), GFP_NOFS);
 391         if (!dirty)
 392                 return -ENOMEM;
 393         dirty->root = root;
 394         dirty->latest_root = latest;
 395         list_add(&dirty->list, dead_list);
 396         return 0;
 397 }
 398
 399 static noinline int add_dirty_roots(struct btrfs_trans_handle *trans,
 400                                     struct radix_tree_root *radix,
 401                                     struct list_head *list)
 402 {
 403         struct btrfs_dirty_root *dirty;
 404         struct btrfs_root *gang[8];
 405         struct btrfs_root *root;
 406         int i;
 407         int ret;
 408         int err = 0;
 409         u32 refs;
 410
 411         while(1) {
 412                 ret = radix_tree_gang_lookup_tag(radix, (void **)gang, 0,
 413                                                  ARRAY_SIZE(gang),
 414                                                  BTRFS_ROOT_TRANS_TAG);
 415                 if (ret == 0)
 416                         break;
 417                 for (i = 0; i < ret; i++) {
 418                         root = gang[i];
 419                         radix_tree_tag_clear(radix,
 420                                      (unsigned long)root->root_key.objectid,
 421                                      BTRFS_ROOT_TRANS_TAG);
 422
 423                         BUG_ON(!root->ref_tree);
 424                         dirty = root->dirty_root;
 425
 426                         if (root->commit_root == root->node) {
 427                                 WARN_ON(root->node->start !=
 428                                         btrfs_root_bytenr(&root->root_item));
 429
 430                                 free_extent_buffer(root->commit_root);
 431                                 root->commit_root = NULL;
 432
 433                                 spin_lock(&root->list_lock);
 434                                 list_del_init(&dirty->root->dead_list);
 435                                 spin_unlock(&root->list_lock);
 436
 437                                 kfree(dirty->root);
 438                                 kfree(dirty);
 439
 440                                 /* make sure to update the root on disk
 441                                  * so we get any updates to the block used
 442                                  * counts
 443                                  */
 444                                 err = btrfs_update_root(trans,
 445                                                 root->fs_info->tree_root,
 446                                                 &root->root_key,
 447                                                 &root->root_item);
 448                                 continue;
 449                         }
 450
 451                         memset(&root->root_item.drop_progress, 0,
 452                                sizeof(struct btrfs_disk_key));
 453                         root->root_item.drop_level = 0;
 454                         root->commit_root = NULL;
 455                         root->root_key.offset = root->fs_info->generation;
 456                         btrfs_set_root_bytenr(&root->root_item,
 457                                               root->node->start);
 458                         btrfs_set_root_level(&root->root_item,
 459                                              btrfs_header_level(root->node));
 460                         err = btrfs_insert_root(trans, root->fs_info->tree_root,
 461                                                 &root->root_key,
 462                                                 &root->root_item);
 463                         if (err)
 464                                 break;
 465
 466                         refs = btrfs_root_refs(&dirty->root->root_item);
 467                         btrfs_set_root_refs(&dirty->root->root_item, refs - 1);
 468                         err = btrfs_update_root(trans, root->fs_info->tree_root,
 469                                                 &dirty->root->root_key,
 470                                                 &dirty->root->root_item);
 471
 472                         BUG_ON(err);
 473                         if (refs == 1) {
 474                                 list_add(&dirty->list, list);
 475                         } else {
 476                                 WARN_ON(1);
 477                                 free_extent_buffer(dirty->root->node);
 478                                 kfree(dirty->root);
 479                                 kfree(dirty);
 480                         }
 481                 }
 482         }
 483         return err;
 484 }
 485
 486 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 487 {
 488         struct btrfs_fs_info *info = root->fs_info;
 489         int ret;
 490         struct btrfs_trans_handle *trans;
 491         unsigned long nr;
 492
 493         smp_mb();
 494         if (root->defrag_running)
 495                 return 0;
 496         trans = btrfs_start_transaction(root, 1);
 497         while (1) {
 498                 root->defrag_running = 1;
 499                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 500                 nr = trans->blocks_used;
 501                 btrfs_end_transaction(trans, root);
 502                 btrfs_btree_balance_dirty(info->tree_root, nr);
 503                 cond_resched();
 504
 505                 trans = btrfs_start_transaction(root, 1);
 506                 if (root->fs_info->closing || ret != -EAGAIN)
 507                         break;
 508         }
 509         root->defrag_running = 0;
 510         smp_mb();
 511         btrfs_end_transaction(trans, root);
 512         return 0;
 513 }
 514
 515 static noinline int drop_dirty_roots(struct btrfs_root *tree_root,
 516                                      struct list_head *list)
 517 {
 518         struct btrfs_dirty_root *dirty;
 519         struct btrfs_trans_handle *trans;
 520         unsigned long nr;
 521         u64 num_bytes;
 522         u64 bytes_used;
 523         u64 max_useless;
 524         int ret = 0;
 525         int err;
 526
 527         while(!list_empty(list)) {
 528                 struct btrfs_root *root;
 529
 530                 dirty = list_entry(list->prev, struct btrfs_dirty_root, list);
 531                 list_del_init(&dirty->list);
 532
 533                 num_bytes = btrfs_root_used(&dirty->root->root_item);
 534                 root = dirty->latest_root;
 535                 atomic_inc(&root->fs_info->throttles);
 536
 537                 mutex_lock(&root->fs_info->drop_mutex);
 538                 while(1) {
 539                         trans = btrfs_start_transaction(tree_root, 1);
 540                         ret = btrfs_drop_snapshot(trans, dirty->root);
 541                         if (ret != -EAGAIN) {
 542                                 break;
 543                         }
 544
 545                         err = btrfs_update_root(trans,
 546                                         tree_root,
 547                                         &dirty->root->root_key,
 548                                         &dirty->root->root_item);
 549                         if (err)
 550                                 ret = err;
 551                         nr = trans->blocks_used;
 552                         ret = btrfs_end_transaction(trans, tree_root);
 553                         BUG_ON(ret);
 554
 555                         mutex_unlock(&root->fs_info->drop_mutex);
 556                         btrfs_btree_balance_dirty(tree_root, nr);
 557                         cond_resched();
 558                         mutex_lock(&root->fs_info->drop_mutex);
 559                 }
 560                 BUG_ON(ret);
 561                 atomic_dec(&root->fs_info->throttles);
 562                 wake_up(&root->fs_info->transaction_throttle);
 563
 564                 mutex_lock(&root->fs_info->alloc_mutex);
 565                 num_bytes -= btrfs_root_used(&dirty->root->root_item);
 566                 bytes_used = btrfs_root_used(&root->root_item);
 567                 if (num_bytes) {
 568                         record_root_in_trans(root);
 569                         btrfs_set_root_used(&root->root_item,
 570                                             bytes_used - num_bytes);
 571                 }
 572                 mutex_unlock(&root->fs_info->alloc_mutex);
 573
 574                 ret = btrfs_del_root(trans, tree_root, &dirty->root->root_key);
 575                 if (ret) {
 576                         BUG();
 577                         break;
 578                 }
 579                 mutex_unlock(&root->fs_info->drop_mutex);
 580
 581                 spin_lock(&root->list_lock);
 582                 list_del_init(&dirty->root->dead_list);
 583                 if (!list_empty(&root->dead_list)) {
 584                         struct btrfs_root *oldest;
 585                         oldest = list_entry(root->dead_list.prev,
 586                                             struct btrfs_root, dead_list);
 587                         max_useless = oldest->root_key.offset - 1;
 588                 } else {
 589                         max_useless = root->root_key.offset - 1;
 590                 }
 591                 spin_unlock(&root->list_lock);
 592
 593                 nr = trans->blocks_used;
 594                 ret = btrfs_end_transaction(trans, tree_root);
 595                 BUG_ON(ret);
 596
 597                 ret = btrfs_remove_leaf_refs(root, max_useless);
 598                 BUG_ON(ret);
 599
 600                 free_extent_buffer(dirty->root->node);
 601                 kfree(dirty->root);
 602                 kfree(dirty);
 603
 604                 btrfs_btree_balance_dirty(tree_root, nr);
 605                 cond_resched();
 606         }
 607         return ret;
 608 }
 609
 610 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 611                                    struct btrfs_fs_info *fs_info,
 612                                    struct btrfs_pending_snapshot *pending)
 613 {
 614         struct btrfs_key key;
 615         struct btrfs_root_item *new_root_item;
 616         struct btrfs_root *tree_root = fs_info->tree_root;
 617         struct btrfs_root *root = pending->root;
 618         struct extent_buffer *tmp;
 619         struct extent_buffer *old;
 620         int ret;
 621         int namelen;
 622         u64 objectid;
 623
 624         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 625         if (!new_root_item) {
 626                 ret = -ENOMEM;
 627                 goto fail;
 628         }
 629         ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
 630         if (ret)
 631                 goto fail;
 632
 633         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
 634
 635         key.objectid = objectid;
 636         key.offset = 1;
 637         btrfs_set_key_type(&key, BTRFS_ROOT_ITEM_KEY);
 638
 639         old = btrfs_lock_root_node(root);
 640         btrfs_cow_block(trans, root, old, NULL, 0, &old, 0);
 641
 642         btrfs_copy_root(trans, root, old, &tmp, objectid);
 643         btrfs_tree_unlock(old);
 644         free_extent_buffer(old);
 645
 646         btrfs_set_root_bytenr(new_root_item, tmp->start);
 647         btrfs_set_root_level(new_root_item, btrfs_header_level(tmp));
 648         ret = btrfs_insert_root(trans, root->fs_info->tree_root, &key,
 649                                 new_root_item);
 650         btrfs_tree_unlock(tmp);
 651         free_extent_buffer(tmp);
 652         if (ret)
 653                 goto fail;
 654
 655         /*
 656          * insert the directory item
 657          */
 658         key.offset = (u64)-1;
 659         namelen = strlen(pending->name);
 660         ret = btrfs_insert_dir_item(trans, root->fs_info->tree_root,
 661                                     pending->name, namelen,
 662                                     root->fs_info->sb->s_root->d_inode->i_ino,
 663                                     &key, BTRFS_FT_DIR, 0);
 664
 665         if (ret)
 666                 goto fail;
 667
 668         ret = btrfs_insert_inode_ref(trans, root->fs_info->tree_root,
 669                              pending->name, strlen(pending->name), objectid,
 670                              root->fs_info->sb->s_root->d_inode->i_ino, 0);
 671
 672         /* Invalidate existing dcache entry for new snapshot. */
 673         btrfs_invalidate_dcache_root(root, pending->name, namelen);
 674
 675 fail:
 676         kfree(new_root_item);
 677         return ret;
 678 }
 679
 680 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
 681                                              struct btrfs_fs_info *fs_info)
 682 {
 683         struct btrfs_pending_snapshot *pending;
 684         struct list_head *head = &trans->transaction->pending_snapshots;
 685         int ret;
 686
 687         while(!list_empty(head)) {
 688                 pending = list_entry(head->next,
 689                                      struct btrfs_pending_snapshot, list);
 690                 ret = create_pending_snapshot(trans, fs_info, pending);
 691                 BUG_ON(ret);
 692                 list_del(&pending->list);
 693                 kfree(pending->name);
 694                 kfree(pending);
 695         }
 696         return 0;
 697 }
 698
 699 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
 700                              struct btrfs_root *root)
 701 {
 702         unsigned long joined = 0;
 703         unsigned long timeout = 1;
 704         struct btrfs_transaction *cur_trans;
 705         struct btrfs_transaction *prev_trans = NULL;
 706         struct btrfs_root *chunk_root = root->fs_info->chunk_root;
 707         struct list_head dirty_fs_roots;
 708         struct extent_io_tree *pinned_copy;
 709         DEFINE_WAIT(wait);
 710         int ret;
 711
 712         INIT_LIST_HEAD(&dirty_fs_roots);
 713
 714         mutex_lock(&root->fs_info->trans_mutex);
 715         if (trans->transaction->in_commit) {
 716                 cur_trans = trans->transaction;
 717                 trans->transaction->use_count++;
 718                 mutex_unlock(&root->fs_info->trans_mutex);
 719                 btrfs_end_transaction(trans, root);
 720
 721                 ret = wait_for_commit(root, cur_trans);
 722                 BUG_ON(ret);
 723
 724                 mutex_lock(&root->fs_info->trans_mutex);
 725                 put_transaction(cur_trans);
 726                 mutex_unlock(&root->fs_info->trans_mutex);
 727
 728                 return 0;
 729         }
 730
 731         pinned_copy = kmalloc(sizeof(*pinned_copy), GFP_NOFS);
 732         if (!pinned_copy)
 733                 return -ENOMEM;
 734
 735         extent_io_tree_init(pinned_copy,
 736                              root->fs_info->btree_inode->i_mapping, GFP_NOFS);
 737
 738         trans->transaction->in_commit = 1;
 739         trans->transaction->blocked = 1;
 740         cur_trans = trans->transaction;
 741         if (cur_trans->list.prev != &root->fs_info->trans_list) {
 742                 prev_trans = list_entry(cur_trans->list.prev,
 743                                         struct btrfs_transaction, list);
 744                 if (!prev_trans->commit_done) {
 745                         prev_trans->use_count++;
 746                         mutex_unlock(&root->fs_info->trans_mutex);
 747
 748                         wait_for_commit(root, prev_trans);
 749
 750                         mutex_lock(&root->fs_info->trans_mutex);
 751                         put_transaction(prev_trans);
 752                 }
 753         }
 754
 755         do {
 756                 joined = cur_trans->num_joined;
 757                 WARN_ON(cur_trans != trans->transaction);
 758                 prepare_to_wait(&cur_trans->writer_wait, &wait,
 759                                 TASK_UNINTERRUPTIBLE);
 760
 761                 if (cur_trans->num_writers > 1)
 762                         timeout = MAX_SCHEDULE_TIMEOUT;
 763                 else
 764                         timeout = 1;
 765
 766                 mutex_unlock(&root->fs_info->trans_mutex);
 767
 768                 schedule_timeout(timeout);
 769
 770                 mutex_lock(&root->fs_info->trans_mutex);
 771                 finish_wait(&cur_trans->writer_wait, &wait);
 772         } while (cur_trans->num_writers > 1 ||
 773                  (cur_trans->num_joined != joined));
 774
 775         ret = create_pending_snapshots(trans, root->fs_info);
 776         BUG_ON(ret);
 777
 778         WARN_ON(cur_trans != trans->transaction);
 779
 780         ret = add_dirty_roots(trans, &root->fs_info->fs_roots_radix,
 781                               &dirty_fs_roots);
 782         BUG_ON(ret);
 783
 784         ret = btrfs_commit_tree_roots(trans, root);
 785         BUG_ON(ret);
 786
 787         cur_trans = root->fs_info->running_transaction;
 788         spin_lock(&root->fs_info->new_trans_lock);
 789         root->fs_info->running_transaction = NULL;
 790         spin_unlock(&root->fs_info->new_trans_lock);
 791         btrfs_set_super_generation(&root->fs_info->super_copy,
 792                                    cur_trans->transid);
 793         btrfs_set_super_root(&root->fs_info->super_copy,
 794                              root->fs_info->tree_root->node->start);
 795         btrfs_set_super_root_level(&root->fs_info->super_copy,
 796                            btrfs_header_level(root->fs_info->tree_root->node));
 797
 798         btrfs_set_super_chunk_root(&root->fs_info->super_copy,
 799                                    chunk_root->node->start);
 800         btrfs_set_super_chunk_root_level(&root->fs_info->super_copy,
 801                                          btrfs_header_level(chunk_root->node));
 802         memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
 803                sizeof(root->fs_info->super_copy));
 804
 805         btrfs_copy_pinned(root, pinned_copy);
 806
 807         trans->transaction->blocked = 0;
 808         wake_up(&root->fs_info->transaction_throttle);
 809         wake_up(&root->fs_info->transaction_wait);
 810
 811         mutex_unlock(&root->fs_info->trans_mutex);
 812         ret = btrfs_write_and_wait_transaction(trans, root);
 813         BUG_ON(ret);
 814         write_ctree_super(trans, root);
 815
 816         btrfs_finish_extent_commit(trans, root, pinned_copy);
 817         mutex_lock(&root->fs_info->trans_mutex);
 818
 819         kfree(pinned_copy);
 820
 821         cur_trans->commit_done = 1;
 822         root->fs_info->last_trans_committed = cur_trans->transid;
 823         wake_up(&cur_trans->commit_wait);
 824         put_transaction(cur_trans);
 825         put_transaction(cur_trans);
 826
 827         list_splice_init(&dirty_fs_roots, &root->fs_info->dead_roots);
 828         if (root->fs_info->closing)
 829                 list_splice_init(&root->fs_info->dead_roots, &dirty_fs_roots);
 830
 831         mutex_unlock(&root->fs_info->trans_mutex);
 832         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 833
 834         if (root->fs_info->closing) {
 835                 drop_dirty_roots(root->fs_info->tree_root, &dirty_fs_roots);
 836         }
 837         return ret;
 838 }
 839
 840 int btrfs_clean_old_snapshots(struct btrfs_root *root)
 841 {
 842         struct list_head dirty_roots;
 843         INIT_LIST_HEAD(&dirty_roots);
 844 again:
 845         mutex_lock(&root->fs_info->trans_mutex);
 846         list_splice_init(&root->fs_info->dead_roots, &dirty_roots);
 847         mutex_unlock(&root->fs_info->trans_mutex);
 848
 849         if (!list_empty(&dirty_roots)) {
 850                 drop_dirty_roots(root, &dirty_roots);
 851                 goto again;
 852         }
 853         return 0;
 854 }