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