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/slab.h>
  21 #include <linux/sched.h>
  22 #include <linux/writeback.h>
  23 #include <linux/pagemap.h>
  24 #include <linux/blkdev.h>
  25 #include "ctree.h"
  26 #include "disk-io.h"
  27 #include "transaction.h"
  28 #include "locking.h"
  29 #include "tree-log.h"
  30
  31 #define BTRFS_ROOT_TRANS_TAG 0
  32
  33 static noinline void put_transaction(struct btrfs_transaction *transaction)
  34 {
  35         WARN_ON(atomic_read(&transaction->use_count) == 0);
  36         if (atomic_dec_and_test(&transaction->use_count)) {
  37                 memset(transaction, 0, sizeof(*transaction));
  38                 kmem_cache_free(btrfs_transaction_cachep, transaction);
  39         }
  40 }
  41
  42 static noinline void switch_commit_root(struct btrfs_root *root)
  43 {
  44         free_extent_buffer(root->commit_root);
  45         root->commit_root = btrfs_root_node(root);
  46 }
  47
  48 /*
  49  * either allocate a new transaction or hop into the existing one
  50  */
  51 static noinline int join_transaction(struct btrfs_root *root)
  52 {
  53         struct btrfs_transaction *cur_trans;
  54         cur_trans = root->fs_info->running_transaction;
  55         if (!cur_trans) {
  56                 cur_trans = kmem_cache_alloc(btrfs_transaction_cachep,
  57                                              GFP_NOFS);
  58                 if (!cur_trans)
  59                         return -ENOMEM;
  60                 root->fs_info->generation++;
  61                 atomic_set(&cur_trans->num_writers, 1);
  62                 cur_trans->num_joined = 0;
  63                 cur_trans->transid = root->fs_info->generation;
  64                 init_waitqueue_head(&cur_trans->writer_wait);
  65                 init_waitqueue_head(&cur_trans->commit_wait);
  66                 cur_trans->in_commit = 0;
  67                 cur_trans->blocked = 0;
  68                 atomic_set(&cur_trans->use_count, 1);
  69                 cur_trans->commit_done = 0;
  70                 cur_trans->start_time = get_seconds();
  71
  72                 cur_trans->delayed_refs.root = RB_ROOT;
  73                 cur_trans->delayed_refs.num_entries = 0;
  74                 cur_trans->delayed_refs.num_heads_ready = 0;
  75                 cur_trans->delayed_refs.num_heads = 0;
  76                 cur_trans->delayed_refs.flushing = 0;
  77                 cur_trans->delayed_refs.run_delayed_start = 0;
  78                 spin_lock_init(&cur_trans->delayed_refs.lock);
  79
  80                 INIT_LIST_HEAD(&cur_trans->pending_snapshots);
  81                 list_add_tail(&cur_trans->list, &root->fs_info->trans_list);
  82                 extent_io_tree_init(&cur_trans->dirty_pages,
  83                                      root->fs_info->btree_inode->i_mapping,
  84                                      GFP_NOFS);
  85                 spin_lock(&root->fs_info->new_trans_lock);
  86                 root->fs_info->running_transaction = cur_trans;
  87                 spin_unlock(&root->fs_info->new_trans_lock);
  88         } else {
  89                 atomic_inc(&cur_trans->num_writers);
  90                 cur_trans->num_joined++;
  91         }
  92
  93         return 0;
  94 }
  95
  96 /*
  97  * this does all the record keeping required to make sure that a reference
  98  * counted root is properly recorded in a given transaction.  This is required
  99  * to make sure the old root from before we joined the transaction is deleted
 100  * when the transaction commits
 101  */
 102 static noinline int record_root_in_trans(struct btrfs_trans_handle *trans,
 103                                          struct btrfs_root *root)
 104 {
 105         if (root->ref_cows && root->last_trans < trans->transid) {
 106                 WARN_ON(root == root->fs_info->extent_root);
 107                 WARN_ON(root->commit_root != root->node);
 108
 109                 radix_tree_tag_set(&root->fs_info->fs_roots_radix,
 110                            (unsigned long)root->root_key.objectid,
 111                            BTRFS_ROOT_TRANS_TAG);
 112                 root->last_trans = trans->transid;
 113                 btrfs_init_reloc_root(trans, root);
 114         }
 115         return 0;
 116 }
 117
 118 int btrfs_record_root_in_trans(struct btrfs_trans_handle *trans,
 119                                struct btrfs_root *root)
 120 {
 121         if (!root->ref_cows)
 122                 return 0;
 123
 124         mutex_lock(&root->fs_info->trans_mutex);
 125         if (root->last_trans == trans->transid) {
 126                 mutex_unlock(&root->fs_info->trans_mutex);
 127                 return 0;
 128         }
 129
 130         record_root_in_trans(trans, root);
 131         mutex_unlock(&root->fs_info->trans_mutex);
 132         return 0;
 133 }
 134
 135 /* wait for commit against the current transaction to become unblocked
 136  * when this is done, it is safe to start a new transaction, but the current
 137  * transaction might not be fully on disk.
 138  */
 139 static void wait_current_trans(struct btrfs_root *root)
 140 {
 141         struct btrfs_transaction *cur_trans;
 142
 143         cur_trans = root->fs_info->running_transaction;
 144         if (cur_trans && cur_trans->blocked) {
 145                 DEFINE_WAIT(wait);
 146                 atomic_inc(&cur_trans->use_count);
 147                 while (1) {
 148                         prepare_to_wait(&root->fs_info->transaction_wait, &wait,
 149                                         TASK_UNINTERRUPTIBLE);
 150                         if (!cur_trans->blocked)
 151                                 break;
 152                         mutex_unlock(&root->fs_info->trans_mutex);
 153                         schedule();
 154                         mutex_lock(&root->fs_info->trans_mutex);
 155                 }
 156                 finish_wait(&root->fs_info->transaction_wait, &wait);
 157                 put_transaction(cur_trans);
 158         }
 159 }
 160
 161 enum btrfs_trans_type {
 162         TRANS_START,
 163         TRANS_JOIN,
 164         TRANS_USERSPACE,
 165         TRANS_JOIN_NOLOCK,
 166 };
 167
 168 static int may_wait_transaction(struct btrfs_root *root, int type)
 169 {
 170         if (!root->fs_info->log_root_recovering &&
 171             ((type == TRANS_START && !root->fs_info->open_ioctl_trans) ||
 172              type == TRANS_USERSPACE))
 173                 return 1;
 174         return 0;
 175 }
 176
 177 static struct btrfs_trans_handle *start_transaction(struct btrfs_root *root,
 178                                                     u64 num_items, int type)
 179 {
 180         struct btrfs_trans_handle *h;
 181         struct btrfs_transaction *cur_trans;
 182         int retries = 0;
 183         int ret;
 184
 185         if (root->fs_info->fs_state & BTRFS_SUPER_FLAG_ERROR)
 186                 return ERR_PTR(-EROFS);
 187
 188         if (current->journal_info) {
 189                 WARN_ON(type != TRANS_JOIN && type != TRANS_JOIN_NOLOCK);
 190                 h = current->journal_info;
 191                 h->use_count++;
 192                 h->orig_rsv = h->block_rsv;
 193                 h->block_rsv = NULL;
 194                 goto got_it;
 195         }
 196 again:
 197         h = kmem_cache_alloc(btrfs_trans_handle_cachep, GFP_NOFS);
 198         if (!h)
 199                 return ERR_PTR(-ENOMEM);
 200
 201         if (type != TRANS_JOIN_NOLOCK)
 202                 mutex_lock(&root->fs_info->trans_mutex);
 203         if (may_wait_transaction(root, type))
 204                 wait_current_trans(root);
 205
 206         ret = join_transaction(root);
 207         if (ret < 0) {
 208                 kmem_cache_free(btrfs_trans_handle_cachep, h);
 209                 if (type != TRANS_JOIN_NOLOCK)
 210                         mutex_unlock(&root->fs_info->trans_mutex);
 211                 return ERR_PTR(ret);
 212         }
 213
 214         cur_trans = root->fs_info->running_transaction;
 215         atomic_inc(&cur_trans->use_count);
 216         if (type != TRANS_JOIN_NOLOCK)
 217                 mutex_unlock(&root->fs_info->trans_mutex);
 218
 219         h->transid = cur_trans->transid;
 220         h->transaction = cur_trans;
 221         h->blocks_used = 0;
 222         h->block_group = 0;
 223         h->bytes_reserved = 0;
 224         h->delayed_ref_updates = 0;
 225         h->use_count = 1;
 226         h->block_rsv = NULL;
 227         h->orig_rsv = NULL;
 228
 229         smp_mb();
 230         if (cur_trans->blocked && may_wait_transaction(root, type)) {
 231                 btrfs_commit_transaction(h, root);
 232                 goto again;
 233         }
 234
 235         if (num_items > 0) {
 236                 ret = btrfs_trans_reserve_metadata(h, root, num_items);
 237                 if (ret == -EAGAIN && !retries) {
 238                         retries++;
 239                         btrfs_commit_transaction(h, root);
 240                         goto again;
 241                 } else if (ret == -EAGAIN) {
 242                         /*
 243                          * We have already retried and got EAGAIN, so really we
 244                          * don't have space, so set ret to -ENOSPC.
 245                          */
 246                         ret = -ENOSPC;
 247                 }
 248
 249                 if (ret < 0) {
 250                         btrfs_end_transaction(h, root);
 251                         return ERR_PTR(ret);
 252                 }
 253         }
 254
 255 got_it:
 256         if (type != TRANS_JOIN_NOLOCK)
 257                 mutex_lock(&root->fs_info->trans_mutex);
 258         record_root_in_trans(h, root);
 259         if (type != TRANS_JOIN_NOLOCK)
 260                 mutex_unlock(&root->fs_info->trans_mutex);
 261
 262         if (!current->journal_info && type != TRANS_USERSPACE)
 263                 current->journal_info = h;
 264         return h;
 265 }
 266
 267 struct btrfs_trans_handle *btrfs_start_transaction(struct btrfs_root *root,
 268                                                    int num_items)
 269 {
 270         return start_transaction(root, num_items, TRANS_START);
 271 }
 272 struct btrfs_trans_handle *btrfs_join_transaction(struct btrfs_root *root)
 273 {
 274         return start_transaction(root, 0, TRANS_JOIN);
 275 }
 276
 277 struct btrfs_trans_handle *btrfs_join_transaction_nolock(struct btrfs_root *root)
 278 {
 279         return start_transaction(root, 0, TRANS_JOIN_NOLOCK);
 280 }
 281
 282 struct btrfs_trans_handle *btrfs_start_ioctl_transaction(struct btrfs_root *root)
 283 {
 284         return start_transaction(root, 0, TRANS_USERSPACE);
 285 }
 286
 287 /* wait for a transaction commit to be fully complete */
 288 static noinline int wait_for_commit(struct btrfs_root *root,
 289                                     struct btrfs_transaction *commit)
 290 {
 291         DEFINE_WAIT(wait);
 292         mutex_lock(&root->fs_info->trans_mutex);
 293         while (!commit->commit_done) {
 294                 prepare_to_wait(&commit->commit_wait, &wait,
 295                                 TASK_UNINTERRUPTIBLE);
 296                 if (commit->commit_done)
 297                         break;
 298                 mutex_unlock(&root->fs_info->trans_mutex);
 299                 schedule();
 300                 mutex_lock(&root->fs_info->trans_mutex);
 301         }
 302         mutex_unlock(&root->fs_info->trans_mutex);
 303         finish_wait(&commit->commit_wait, &wait);
 304         return 0;
 305 }
 306
 307 int btrfs_wait_for_commit(struct btrfs_root *root, u64 transid)
 308 {
 309         struct btrfs_transaction *cur_trans = NULL, *t;
 310         int ret;
 311
 312         mutex_lock(&root->fs_info->trans_mutex);
 313
 314         ret = 0;
 315         if (transid) {
 316                 if (transid <= root->fs_info->last_trans_committed)
 317                         goto out_unlock;
 318
 319                 /* find specified transaction */
 320                 list_for_each_entry(t, &root->fs_info->trans_list, list) {
 321                         if (t->transid == transid) {
 322                                 cur_trans = t;
 323                                 break;
 324                         }
 325                         if (t->transid > transid)
 326                                 break;
 327                 }
 328                 ret = -EINVAL;
 329                 if (!cur_trans)
 330                         goto out_unlock;  /* bad transid */
 331         } else {
 332                 /* find newest transaction that is committing | committed */
 333                 list_for_each_entry_reverse(t, &root->fs_info->trans_list,
 334                                             list) {
 335                         if (t->in_commit) {
 336                                 if (t->commit_done)
 337                                         goto out_unlock;
 338                                 cur_trans = t;
 339                                 break;
 340                         }
 341                 }
 342                 if (!cur_trans)
 343                         goto out_unlock;  /* nothing committing|committed */
 344         }
 345
 346         atomic_inc(&cur_trans->use_count);
 347         mutex_unlock(&root->fs_info->trans_mutex);
 348
 349         wait_for_commit(root, cur_trans);
 350
 351         mutex_lock(&root->fs_info->trans_mutex);
 352         put_transaction(cur_trans);
 353         ret = 0;
 354 out_unlock:
 355         mutex_unlock(&root->fs_info->trans_mutex);
 356         return ret;
 357 }
 358
 359 #if 0
 360 /*
 361  * rate limit against the drop_snapshot code.  This helps to slow down new
 362  * operations if the drop_snapshot code isn't able to keep up.
 363  */
 364 static void throttle_on_drops(struct btrfs_root *root)
 365 {
 366         struct btrfs_fs_info *info = root->fs_info;
 367         int harder_count = 0;
 368
 369 harder:
 370         if (atomic_read(&info->throttles)) {
 371                 DEFINE_WAIT(wait);
 372                 int thr;
 373                 thr = atomic_read(&info->throttle_gen);
 374
 375                 do {
 376                         prepare_to_wait(&info->transaction_throttle,
 377                                         &wait, TASK_UNINTERRUPTIBLE);
 378                         if (!atomic_read(&info->throttles)) {
 379                                 finish_wait(&info->transaction_throttle, &wait);
 380                                 break;
 381                         }
 382                         schedule();
 383                         finish_wait(&info->transaction_throttle, &wait);
 384                 } while (thr == atomic_read(&info->throttle_gen));
 385                 harder_count++;
 386
 387                 if (root->fs_info->total_ref_cache_size > 1 * 1024 * 1024 &&
 388                     harder_count < 2)
 389                         goto harder;
 390
 391                 if (root->fs_info->total_ref_cache_size > 5 * 1024 * 1024 &&
 392                     harder_count < 10)
 393                         goto harder;
 394
 395                 if (root->fs_info->total_ref_cache_size > 10 * 1024 * 1024 &&
 396                     harder_count < 20)
 397                         goto harder;
 398         }
 399 }
 400 #endif
 401
 402 void btrfs_throttle(struct btrfs_root *root)
 403 {
 404         mutex_lock(&root->fs_info->trans_mutex);
 405         if (!root->fs_info->open_ioctl_trans)
 406                 wait_current_trans(root);
 407         mutex_unlock(&root->fs_info->trans_mutex);
 408 }
 409
 410 static int should_end_transaction(struct btrfs_trans_handle *trans,
 411                                   struct btrfs_root *root)
 412 {
 413         int ret;
 414         ret = btrfs_block_rsv_check(trans, root,
 415                                     &root->fs_info->global_block_rsv, 0, 5);
 416         return ret ? 1 : 0;
 417 }
 418
 419 int btrfs_should_end_transaction(struct btrfs_trans_handle *trans,
 420                                  struct btrfs_root *root)
 421 {
 422         struct btrfs_transaction *cur_trans = trans->transaction;
 423         int updates;
 424
 425         if (cur_trans->blocked || cur_trans->delayed_refs.flushing)
 426                 return 1;
 427
 428         updates = trans->delayed_ref_updates;
 429         trans->delayed_ref_updates = 0;
 430         if (updates)
 431                 btrfs_run_delayed_refs(trans, root, updates);
 432
 433         return should_end_transaction(trans, root);
 434 }
 435
 436 static int __btrfs_end_transaction(struct btrfs_trans_handle *trans,
 437                           struct btrfs_root *root, int throttle, int lock)
 438 {
 439         struct btrfs_transaction *cur_trans = trans->transaction;
 440         struct btrfs_fs_info *info = root->fs_info;
 441         int count = 0;
 442
 443         if (--trans->use_count) {
 444                 trans->block_rsv = trans->orig_rsv;
 445                 return 0;
 446         }
 447
 448         while (count < 4) {
 449                 unsigned long cur = trans->delayed_ref_updates;
 450                 trans->delayed_ref_updates = 0;
 451                 if (cur &&
 452                     trans->transaction->delayed_refs.num_heads_ready > 64) {
 453                         trans->delayed_ref_updates = 0;
 454
 455                         /*
 456                          * do a full flush if the transaction is trying
 457                          * to close
 458                          */
 459                         if (trans->transaction->delayed_refs.flushing)
 460                                 cur = 0;
 461                         btrfs_run_delayed_refs(trans, root, cur);
 462                 } else {
 463                         break;
 464                 }
 465                 count++;
 466         }
 467
 468         btrfs_trans_release_metadata(trans, root);
 469
 470         if (lock && !root->fs_info->open_ioctl_trans &&
 471             should_end_transaction(trans, root))
 472                 trans->transaction->blocked = 1;
 473
 474         if (lock && cur_trans->blocked && !cur_trans->in_commit) {
 475                 if (throttle)
 476                         return btrfs_commit_transaction(trans, root);
 477                 else
 478                         wake_up_process(info->transaction_kthread);
 479         }
 480
 481         WARN_ON(cur_trans != info->running_transaction);
 482         WARN_ON(atomic_read(&cur_trans->num_writers) < 1);
 483         atomic_dec(&cur_trans->num_writers);
 484
 485         smp_mb();
 486         if (waitqueue_active(&cur_trans->writer_wait))
 487                 wake_up(&cur_trans->writer_wait);
 488         put_transaction(cur_trans);
 489
 490         if (current->journal_info == trans)
 491                 current->journal_info = NULL;
 492         memset(trans, 0, sizeof(*trans));
 493         kmem_cache_free(btrfs_trans_handle_cachep, trans);
 494
 495         if (throttle)
 496                 btrfs_run_delayed_iputs(root);
 497
 498         return 0;
 499 }
 500
 501 int btrfs_end_transaction(struct btrfs_trans_handle *trans,
 502                           struct btrfs_root *root)
 503 {
 504         return __btrfs_end_transaction(trans, root, 0, 1);
 505 }
 506
 507 int btrfs_end_transaction_throttle(struct btrfs_trans_handle *trans,
 508                                    struct btrfs_root *root)
 509 {
 510         return __btrfs_end_transaction(trans, root, 1, 1);
 511 }
 512
 513 int btrfs_end_transaction_nolock(struct btrfs_trans_handle *trans,
 514                                  struct btrfs_root *root)
 515 {
 516         return __btrfs_end_transaction(trans, root, 0, 0);
 517 }
 518
 519 /*
 520  * when btree blocks are allocated, they have some corresponding bits set for
 521  * them in one of two extent_io trees.  This is used to make sure all of
 522  * those extents are sent to disk but does not wait on them
 523  */
 524 int btrfs_write_marked_extents(struct btrfs_root *root,
 525                                struct extent_io_tree *dirty_pages, int mark)
 526 {
 527         int ret;
 528         int err = 0;
 529         int werr = 0;
 530         struct page *page;
 531         struct inode *btree_inode = root->fs_info->btree_inode;
 532         u64 start = 0;
 533         u64 end;
 534         unsigned long index;
 535
 536         while (1) {
 537                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 538                                             mark);
 539                 if (ret)
 540                         break;
 541                 while (start <= end) {
 542                         cond_resched();
 543
 544                         index = start >> PAGE_CACHE_SHIFT;
 545                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 546                         page = find_get_page(btree_inode->i_mapping, index);
 547                         if (!page)
 548                                 continue;
 549
 550                         btree_lock_page_hook(page);
 551                         if (!page->mapping) {
 552                                 unlock_page(page);
 553                                 page_cache_release(page);
 554                                 continue;
 555                         }
 556
 557                         if (PageWriteback(page)) {
 558                                 if (PageDirty(page))
 559                                         wait_on_page_writeback(page);
 560                                 else {
 561                                         unlock_page(page);
 562                                         page_cache_release(page);
 563                                         continue;
 564                                 }
 565                         }
 566                         err = write_one_page(page, 0);
 567                         if (err)
 568                                 werr = err;
 569                         page_cache_release(page);
 570                 }
 571         }
 572         if (err)
 573                 werr = err;
 574         return werr;
 575 }
 576
 577 /*
 578  * when btree blocks are allocated, they have some corresponding bits set for
 579  * them in one of two extent_io trees.  This is used to make sure all of
 580  * those extents are on disk for transaction or log commit.  We wait
 581  * on all the pages and clear them from the dirty pages state tree
 582  */
 583 int btrfs_wait_marked_extents(struct btrfs_root *root,
 584                               struct extent_io_tree *dirty_pages, int mark)
 585 {
 586         int ret;
 587         int err = 0;
 588         int werr = 0;
 589         struct page *page;
 590         struct inode *btree_inode = root->fs_info->btree_inode;
 591         u64 start = 0;
 592         u64 end;
 593         unsigned long index;
 594
 595         while (1) {
 596                 ret = find_first_extent_bit(dirty_pages, start, &start, &end,
 597                                             mark);
 598                 if (ret)
 599                         break;
 600
 601                 clear_extent_bits(dirty_pages, start, end, mark, GFP_NOFS);
 602                 while (start <= end) {
 603                         index = start >> PAGE_CACHE_SHIFT;
 604                         start = (u64)(index + 1) << PAGE_CACHE_SHIFT;
 605                         page = find_get_page(btree_inode->i_mapping, index);
 606                         if (!page)
 607                                 continue;
 608                         if (PageDirty(page)) {
 609                                 btree_lock_page_hook(page);
 610                                 wait_on_page_writeback(page);
 611                                 err = write_one_page(page, 0);
 612                                 if (err)
 613                                         werr = err;
 614                         }
 615                         wait_on_page_writeback(page);
 616                         page_cache_release(page);
 617                         cond_resched();
 618                 }
 619         }
 620         if (err)
 621                 werr = err;
 622         return werr;
 623 }
 624
 625 /*
 626  * when btree blocks are allocated, they have some corresponding bits set for
 627  * them in one of two extent_io trees.  This is used to make sure all of
 628  * those extents are on disk for transaction or log commit
 629  */
 630 int btrfs_write_and_wait_marked_extents(struct btrfs_root *root,
 631                                 struct extent_io_tree *dirty_pages, int mark)
 632 {
 633         int ret;
 634         int ret2;
 635
 636         ret = btrfs_write_marked_extents(root, dirty_pages, mark);
 637         ret2 = btrfs_wait_marked_extents(root, dirty_pages, mark);
 638         return ret || ret2;
 639 }
 640
 641 int btrfs_write_and_wait_transaction(struct btrfs_trans_handle *trans,
 642                                      struct btrfs_root *root)
 643 {
 644         if (!trans || !trans->transaction) {
 645                 struct inode *btree_inode;
 646                 btree_inode = root->fs_info->btree_inode;
 647                 return filemap_write_and_wait(btree_inode->i_mapping);
 648         }
 649         return btrfs_write_and_wait_marked_extents(root,
 650                                            &trans->transaction->dirty_pages,
 651                                            EXTENT_DIRTY);
 652 }
 653
 654 /*
 655  * this is used to update the root pointer in the tree of tree roots.
 656  *
 657  * But, in the case of the extent allocation tree, updating the root
 658  * pointer may allocate blocks which may change the root of the extent
 659  * allocation tree.
 660  *
 661  * So, this loops and repeats and makes sure the cowonly root didn't
 662  * change while the root pointer was being updated in the metadata.
 663  */
 664 static int update_cowonly_root(struct btrfs_trans_handle *trans,
 665                                struct btrfs_root *root)
 666 {
 667         int ret;
 668         u64 old_root_bytenr;
 669         u64 old_root_used;
 670         struct btrfs_root *tree_root = root->fs_info->tree_root;
 671
 672         old_root_used = btrfs_root_used(&root->root_item);
 673         btrfs_write_dirty_block_groups(trans, root);
 674
 675         while (1) {
 676                 old_root_bytenr = btrfs_root_bytenr(&root->root_item);
 677                 if (old_root_bytenr == root->node->start &&
 678                     old_root_used == btrfs_root_used(&root->root_item))
 679                         break;
 680
 681                 btrfs_set_root_node(&root->root_item, root->node);
 682                 ret = btrfs_update_root(trans, tree_root,
 683                                         &root->root_key,
 684                                         &root->root_item);
 685                 BUG_ON(ret);
 686
 687                 old_root_used = btrfs_root_used(&root->root_item);
 688                 ret = btrfs_write_dirty_block_groups(trans, root);
 689                 BUG_ON(ret);
 690         }
 691
 692         if (root != root->fs_info->extent_root)
 693                 switch_commit_root(root);
 694
 695         return 0;
 696 }
 697
 698 /*
 699  * update all the cowonly tree roots on disk
 700  */
 701 static noinline int commit_cowonly_roots(struct btrfs_trans_handle *trans,
 702                                          struct btrfs_root *root)
 703 {
 704         struct btrfs_fs_info *fs_info = root->fs_info;
 705         struct list_head *next;
 706         struct extent_buffer *eb;
 707         int ret;
 708
 709         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 710         BUG_ON(ret);
 711
 712         eb = btrfs_lock_root_node(fs_info->tree_root);
 713         btrfs_cow_block(trans, fs_info->tree_root, eb, NULL, 0, &eb);
 714         btrfs_tree_unlock(eb);
 715         free_extent_buffer(eb);
 716
 717         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
 718         BUG_ON(ret);
 719
 720         while (!list_empty(&fs_info->dirty_cowonly_roots)) {
 721                 next = fs_info->dirty_cowonly_roots.next;
 722                 list_del_init(next);
 723                 root = list_entry(next, struct btrfs_root, dirty_list);
 724
 725                 update_cowonly_root(trans, root);
 726         }
 727
 728         down_write(&fs_info->extent_commit_sem);
 729         switch_commit_root(fs_info->extent_root);
 730         up_write(&fs_info->extent_commit_sem);
 731
 732         return 0;
 733 }
 734
 735 /*
 736  * dead roots are old snapshots that need to be deleted.  This allocates
 737  * a dirty root struct and adds it into the list of dead roots that need to
 738  * be deleted
 739  */
 740 int btrfs_add_dead_root(struct btrfs_root *root)
 741 {
 742         mutex_lock(&root->fs_info->trans_mutex);
 743         list_add(&root->root_list, &root->fs_info->dead_roots);
 744         mutex_unlock(&root->fs_info->trans_mutex);
 745         return 0;
 746 }
 747
 748 /*
 749  * update all the cowonly tree roots on disk
 750  */
 751 static noinline int commit_fs_roots(struct btrfs_trans_handle *trans,
 752                                     struct btrfs_root *root)
 753 {
 754         struct btrfs_root *gang[8];
 755         struct btrfs_fs_info *fs_info = root->fs_info;
 756         int i;
 757         int ret;
 758         int err = 0;
 759
 760         while (1) {
 761                 ret = radix_tree_gang_lookup_tag(&fs_info->fs_roots_radix,
 762                                                  (void **)gang, 0,
 763                                                  ARRAY_SIZE(gang),
 764                                                  BTRFS_ROOT_TRANS_TAG);
 765                 if (ret == 0)
 766                         break;
 767                 for (i = 0; i < ret; i++) {
 768                         root = gang[i];
 769                         radix_tree_tag_clear(&fs_info->fs_roots_radix,
 770                                         (unsigned long)root->root_key.objectid,
 771                                         BTRFS_ROOT_TRANS_TAG);
 772
 773                         btrfs_free_log(trans, root);
 774                         btrfs_update_reloc_root(trans, root);
 775                         btrfs_orphan_commit_root(trans, root);
 776
 777                         if (root->commit_root != root->node) {
 778                                 switch_commit_root(root);
 779                                 btrfs_set_root_node(&root->root_item,
 780                                                     root->node);
 781                         }
 782
 783                         err = btrfs_update_root(trans, fs_info->tree_root,
 784                                                 &root->root_key,
 785                                                 &root->root_item);
 786                         if (err)
 787                                 break;
 788                 }
 789         }
 790         return err;
 791 }
 792
 793 /*
 794  * defrag a given btree.  If cacheonly == 1, this won't read from the disk,
 795  * otherwise every leaf in the btree is read and defragged.
 796  */
 797 int btrfs_defrag_root(struct btrfs_root *root, int cacheonly)
 798 {
 799         struct btrfs_fs_info *info = root->fs_info;
 800         struct btrfs_trans_handle *trans;
 801         int ret;
 802         unsigned long nr;
 803
 804         if (xchg(&root->defrag_running, 1))
 805                 return 0;
 806
 807         while (1) {
 808                 trans = btrfs_start_transaction(root, 0);
 809                 if (IS_ERR(trans))
 810                         return PTR_ERR(trans);
 811
 812                 ret = btrfs_defrag_leaves(trans, root, cacheonly);
 813
 814                 nr = trans->blocks_used;
 815                 btrfs_end_transaction(trans, root);
 816                 btrfs_btree_balance_dirty(info->tree_root, nr);
 817                 cond_resched();
 818
 819                 if (root->fs_info->closing || ret != -EAGAIN)
 820                         break;
 821         }
 822         root->defrag_running = 0;
 823         return ret;
 824 }
 825
 826 #if 0
 827 /*
 828  * when dropping snapshots, we generate a ton of delayed refs, and it makes
 829  * sense not to join the transaction while it is trying to flush the current
 830  * queue of delayed refs out.
 831  *
 832  * This is used by the drop snapshot code only
 833  */
 834 static noinline int wait_transaction_pre_flush(struct btrfs_fs_info *info)
 835 {
 836         DEFINE_WAIT(wait);
 837
 838         mutex_lock(&info->trans_mutex);
 839         while (info->running_transaction &&
 840                info->running_transaction->delayed_refs.flushing) {
 841                 prepare_to_wait(&info->transaction_wait, &wait,
 842                                 TASK_UNINTERRUPTIBLE);
 843                 mutex_unlock(&info->trans_mutex);
 844
 845                 schedule();
 846
 847                 mutex_lock(&info->trans_mutex);
 848                 finish_wait(&info->transaction_wait, &wait);
 849         }
 850         mutex_unlock(&info->trans_mutex);
 851         return 0;
 852 }
 853
 854 /*
 855  * Given a list of roots that need to be deleted, call btrfs_drop_snapshot on
 856  * all of them
 857  */
 858 int btrfs_drop_dead_root(struct btrfs_root *root)
 859 {
 860         struct btrfs_trans_handle *trans;
 861         struct btrfs_root *tree_root = root->fs_info->tree_root;
 862         unsigned long nr;
 863         int ret;
 864
 865         while (1) {
 866                 /*
 867                  * we don't want to jump in and create a bunch of
 868                  * delayed refs if the transaction is starting to close
 869                  */
 870                 wait_transaction_pre_flush(tree_root->fs_info);
 871                 trans = btrfs_start_transaction(tree_root, 1);
 872
 873                 /*
 874                  * we've joined a transaction, make sure it isn't
 875                  * closing right now
 876                  */
 877                 if (trans->transaction->delayed_refs.flushing) {
 878                         btrfs_end_transaction(trans, tree_root);
 879                         continue;
 880                 }
 881
 882                 ret = btrfs_drop_snapshot(trans, root);
 883                 if (ret != -EAGAIN)
 884                         break;
 885
 886                 ret = btrfs_update_root(trans, tree_root,
 887                                         &root->root_key,
 888                                         &root->root_item);
 889                 if (ret)
 890                         break;
 891
 892                 nr = trans->blocks_used;
 893                 ret = btrfs_end_transaction(trans, tree_root);
 894                 BUG_ON(ret);
 895
 896                 btrfs_btree_balance_dirty(tree_root, nr);
 897                 cond_resched();
 898         }
 899         BUG_ON(ret);
 900
 901         ret = btrfs_del_root(trans, tree_root, &root->root_key);
 902         BUG_ON(ret);
 903
 904         nr = trans->blocks_used;
 905         ret = btrfs_end_transaction(trans, tree_root);
 906         BUG_ON(ret);
 907
 908         free_extent_buffer(root->node);
 909         free_extent_buffer(root->commit_root);
 910         kfree(root);
 911
 912         btrfs_btree_balance_dirty(tree_root, nr);
 913         return ret;
 914 }
 915 #endif
 916
 917 /*
 918  * new snapshots need to be created at a very specific time in the
 919  * transaction commit.  This does the actual creation
 920  */
 921 static noinline int create_pending_snapshot(struct btrfs_trans_handle *trans,
 922                                    struct btrfs_fs_info *fs_info,
 923                                    struct btrfs_pending_snapshot *pending)
 924 {
 925         struct btrfs_key key;
 926         struct btrfs_root_item *new_root_item;
 927         struct btrfs_root *tree_root = fs_info->tree_root;
 928         struct btrfs_root *root = pending->root;
 929         struct btrfs_root *parent_root;
 930         struct inode *parent_inode;
 931         struct dentry *parent;
 932         struct dentry *dentry;
 933         struct extent_buffer *tmp;
 934         struct extent_buffer *old;
 935         int ret;
 936         u64 to_reserve = 0;
 937         u64 index = 0;
 938         u64 objectid;
 939         u64 root_flags;
 940
 941         new_root_item = kmalloc(sizeof(*new_root_item), GFP_NOFS);
 942         if (!new_root_item) {
 943                 pending->error = -ENOMEM;
 944                 goto fail;
 945         }
 946
 947         ret = btrfs_find_free_objectid(trans, tree_root, 0, &objectid);
 948         if (ret) {
 949                 pending->error = ret;
 950                 goto fail;
 951         }
 952
 953         btrfs_reloc_pre_snapshot(trans, pending, &to_reserve);
 954         btrfs_orphan_pre_snapshot(trans, pending, &to_reserve);
 955
 956         if (to_reserve > 0) {
 957                 ret = btrfs_block_rsv_add(trans, root, &pending->block_rsv,
 958                                           to_reserve);
 959                 if (ret) {
 960                         pending->error = ret;
 961                         goto fail;
 962                 }
 963         }
 964
 965         key.objectid = objectid;
 966         key.offset = (u64)-1;
 967         key.type = BTRFS_ROOT_ITEM_KEY;
 968
 969         trans->block_rsv = &pending->block_rsv;
 970
 971         dentry = pending->dentry;
 972         parent = dget_parent(dentry);
 973         parent_inode = parent->d_inode;
 974         parent_root = BTRFS_I(parent_inode)->root;
 975         record_root_in_trans(trans, parent_root);
 976
 977         /*
 978          * insert the directory item
 979          */
 980         ret = btrfs_set_inode_index(parent_inode, &index);
 981         BUG_ON(ret);
 982         ret = btrfs_insert_dir_item(trans, parent_root,
 983                                 dentry->d_name.name, dentry->d_name.len,
 984                                 parent_inode->i_ino, &key,
 985                                 BTRFS_FT_DIR, index);
 986         BUG_ON(ret);
 987
 988         btrfs_i_size_write(parent_inode, parent_inode->i_size +
 989                                          dentry->d_name.len * 2);
 990         ret = btrfs_update_inode(trans, parent_root, parent_inode);
 991         BUG_ON(ret);
 992
 993         record_root_in_trans(trans, root);
 994         btrfs_set_root_last_snapshot(&root->root_item, trans->transid);
 995         memcpy(new_root_item, &root->root_item, sizeof(*new_root_item));
 996         btrfs_check_and_init_root_item(new_root_item);
 997
 998         root_flags = btrfs_root_flags(new_root_item);
 999         if (pending->readonly)
1000                 root_flags |= BTRFS_ROOT_SUBVOL_RDONLY;
1001         else
1002                 root_flags &= ~BTRFS_ROOT_SUBVOL_RDONLY;
1003         btrfs_set_root_flags(new_root_item, root_flags);
1004
1005         old = btrfs_lock_root_node(root);
1006         btrfs_cow_block(trans, root, old, NULL, 0, &old);
1007         btrfs_set_lock_blocking(old);
1008
1009         btrfs_copy_root(trans, root, old, &tmp, objectid);
1010         btrfs_tree_unlock(old);
1011         free_extent_buffer(old);
1012
1013         btrfs_set_root_node(new_root_item, tmp);
1014         /* record when the snapshot was created in key.offset */
1015         key.offset = trans->transid;
1016         ret = btrfs_insert_root(trans, tree_root, &key, new_root_item);
1017         btrfs_tree_unlock(tmp);
1018         free_extent_buffer(tmp);
1019         BUG_ON(ret);
1020
1021         /*
1022          * insert root back/forward references
1023          */
1024         ret = btrfs_add_root_ref(trans, tree_root, objectid,
1025                                  parent_root->root_key.objectid,
1026                                  parent_inode->i_ino, index,
1027                                  dentry->d_name.name, dentry->d_name.len);
1028         BUG_ON(ret);
1029         dput(parent);
1030
1031         key.offset = (u64)-1;
1032         pending->snap = btrfs_read_fs_root_no_name(root->fs_info, &key);
1033         BUG_ON(IS_ERR(pending->snap));
1034
1035         btrfs_reloc_post_snapshot(trans, pending);
1036         btrfs_orphan_post_snapshot(trans, pending);
1037 fail:
1038         kfree(new_root_item);
1039         btrfs_block_rsv_release(root, &pending->block_rsv, (u64)-1);
1040         return 0;
1041 }
1042
1043 /*
1044  * create all the snapshots we've scheduled for creation
1045  */
1046 static noinline int create_pending_snapshots(struct btrfs_trans_handle *trans,
1047                                              struct btrfs_fs_info *fs_info)
1048 {
1049         struct btrfs_pending_snapshot *pending;
1050         struct list_head *head = &trans->transaction->pending_snapshots;
1051         int ret;
1052
1053         list_for_each_entry(pending, head, list) {
1054                 ret = create_pending_snapshot(trans, fs_info, pending);
1055                 BUG_ON(ret);
1056         }
1057         return 0;
1058 }
1059
1060 static void update_super_roots(struct btrfs_root *root)
1061 {
1062         struct btrfs_root_item *root_item;
1063         struct btrfs_super_block *super;
1064
1065         super = &root->fs_info->super_copy;
1066
1067         root_item = &root->fs_info->chunk_root->root_item;
1068         super->chunk_root = root_item->bytenr;
1069         super->chunk_root_generation = root_item->generation;
1070         super->chunk_root_level = root_item->level;
1071
1072         root_item = &root->fs_info->tree_root->root_item;
1073         super->root = root_item->bytenr;
1074         super->generation = root_item->generation;
1075         super->root_level = root_item->level;
1076         if (super->cache_generation != 0 || btrfs_test_opt(root, SPACE_CACHE))
1077                 super->cache_generation = root_item->generation;
1078 }
1079
1080 int btrfs_transaction_in_commit(struct btrfs_fs_info *info)
1081 {
1082         int ret = 0;
1083         spin_lock(&info->new_trans_lock);
1084         if (info->running_transaction)
1085                 ret = info->running_transaction->in_commit;
1086         spin_unlock(&info->new_trans_lock);
1087         return ret;
1088 }
1089
1090 int btrfs_transaction_blocked(struct btrfs_fs_info *info)
1091 {
1092         int ret = 0;
1093         spin_lock(&info->new_trans_lock);
1094         if (info->running_transaction)
1095                 ret = info->running_transaction->blocked;
1096         spin_unlock(&info->new_trans_lock);
1097         return ret;
1098 }
1099
1100 /*
1101  * wait for the current transaction commit to start and block subsequent
1102  * transaction joins
1103  */
1104 static void wait_current_trans_commit_start(struct btrfs_root *root,
1105                                             struct btrfs_transaction *trans)
1106 {
1107         DEFINE_WAIT(wait);
1108
1109         if (trans->in_commit)
1110                 return;
1111
1112         while (1) {
1113                 prepare_to_wait(&root->fs_info->transaction_blocked_wait, &wait,
1114                                 TASK_UNINTERRUPTIBLE);
1115                 if (trans->in_commit) {
1116                         finish_wait(&root->fs_info->transaction_blocked_wait,
1117                                     &wait);
1118                         break;
1119                 }
1120                 mutex_unlock(&root->fs_info->trans_mutex);
1121                 schedule();
1122                 mutex_lock(&root->fs_info->trans_mutex);
1123                 finish_wait(&root->fs_info->transaction_blocked_wait, &wait);
1124         }
1125 }
1126
1127 /*
1128  * wait for the current transaction to start and then become unblocked.
1129  * caller holds ref.
1130  */
1131 static void wait_current_trans_commit_start_and_unblock(struct btrfs_root *root,
1132                                          struct btrfs_transaction *trans)
1133 {
1134         DEFINE_WAIT(wait);
1135
1136         if (trans->commit_done || (trans->in_commit && !trans->blocked))
1137                 return;
1138
1139         while (1) {
1140                 prepare_to_wait(&root->fs_info->transaction_wait, &wait,
1141                                 TASK_UNINTERRUPTIBLE);
1142                 if (trans->commit_done ||
1143                     (trans->in_commit && !trans->blocked)) {
1144                         finish_wait(&root->fs_info->transaction_wait,
1145                                     &wait);
1146                         break;
1147                 }
1148                 mutex_unlock(&root->fs_info->trans_mutex);
1149                 schedule();
1150                 mutex_lock(&root->fs_info->trans_mutex);
1151                 finish_wait(&root->fs_info->transaction_wait,
1152                             &wait);
1153         }
1154 }
1155
1156 /*
1157  * commit transactions asynchronously. once btrfs_commit_transaction_async
1158  * returns, any subsequent transaction will not be allowed to join.
1159  */
1160 struct btrfs_async_commit {
1161         struct btrfs_trans_handle *newtrans;
1162         struct btrfs_root *root;
1163         struct delayed_work work;
1164 };
1165
1166 static void do_async_commit(struct work_struct *work)
1167 {
1168         struct btrfs_async_commit *ac =
1169                 container_of(work, struct btrfs_async_commit, work.work);
1170
1171         btrfs_commit_transaction(ac->newtrans, ac->root);
1172         kfree(ac);
1173 }
1174
1175 int btrfs_commit_transaction_async(struct btrfs_trans_handle *trans,
1176                                    struct btrfs_root *root,
1177                                    int wait_for_unblock)
1178 {
1179         struct btrfs_async_commit *ac;
1180         struct btrfs_transaction *cur_trans;
1181
1182         ac = kmalloc(sizeof(*ac), GFP_NOFS);
1183         if (!ac)
1184                 return -ENOMEM;
1185
1186         INIT_DELAYED_WORK(&ac->work, do_async_commit);
1187         ac->root = root;
1188         ac->newtrans = btrfs_join_transaction(root);
1189         if (IS_ERR(ac->newtrans)) {
1190                 int err = PTR_ERR(ac->newtrans);
1191                 kfree(ac);
1192                 return err;
1193         }
1194
1195         /* take transaction reference */
1196         mutex_lock(&root->fs_info->trans_mutex);
1197         cur_trans = trans->transaction;
1198         atomic_inc(&cur_trans->use_count);
1199         mutex_unlock(&root->fs_info->trans_mutex);
1200
1201         btrfs_end_transaction(trans, root);
1202         schedule_delayed_work(&ac->work, 0);
1203
1204         /* wait for transaction to start and unblock */
1205         mutex_lock(&root->fs_info->trans_mutex);
1206         if (wait_for_unblock)
1207                 wait_current_trans_commit_start_and_unblock(root, cur_trans);
1208         else
1209                 wait_current_trans_commit_start(root, cur_trans);
1210         put_transaction(cur_trans);
1211         mutex_unlock(&root->fs_info->trans_mutex);
1212
1213         return 0;
1214 }
1215
1216 /*
1217  * btrfs_transaction state sequence:
1218  *    in_commit = 0, blocked = 0  (initial)
1219  *    in_commit = 1, blocked = 1
1220  *    blocked = 0
1221  *    commit_done = 1
1222  */
1223 int btrfs_commit_transaction(struct btrfs_trans_handle *trans,
1224                              struct btrfs_root *root)
1225 {
1226         unsigned long joined = 0;
1227         struct btrfs_transaction *cur_trans;
1228         struct btrfs_transaction *prev_trans = NULL;
1229         DEFINE_WAIT(wait);
1230         int ret;
1231         int should_grow = 0;
1232         unsigned long now = get_seconds();
1233         int flush_on_commit = btrfs_test_opt(root, FLUSHONCOMMIT);
1234
1235         btrfs_run_ordered_operations(root, 0);
1236
1237         /* make a pass through all the delayed refs we have so far
1238          * any runnings procs may add more while we are here
1239          */
1240         ret = btrfs_run_delayed_refs(trans, root, 0);
1241         BUG_ON(ret);
1242
1243         btrfs_trans_release_metadata(trans, root);
1244
1245         cur_trans = trans->transaction;
1246         /*
1247          * set the flushing flag so procs in this transaction have to
1248          * start sending their work down.
1249          */
1250         cur_trans->delayed_refs.flushing = 1;
1251
1252         ret = btrfs_run_delayed_refs(trans, root, 0);
1253         BUG_ON(ret);
1254
1255         mutex_lock(&root->fs_info->trans_mutex);
1256         if (cur_trans->in_commit) {
1257                 atomic_inc(&cur_trans->use_count);
1258                 mutex_unlock(&root->fs_info->trans_mutex);
1259                 btrfs_end_transaction(trans, root);
1260
1261                 ret = wait_for_commit(root, cur_trans);
1262                 BUG_ON(ret);
1263
1264                 mutex_lock(&root->fs_info->trans_mutex);
1265                 put_transaction(cur_trans);
1266                 mutex_unlock(&root->fs_info->trans_mutex);
1267
1268                 return 0;
1269         }
1270
1271         trans->transaction->in_commit = 1;
1272         trans->transaction->blocked = 1;
1273         wake_up(&root->fs_info->transaction_blocked_wait);
1274
1275         if (cur_trans->list.prev != &root->fs_info->trans_list) {
1276                 prev_trans = list_entry(cur_trans->list.prev,
1277                                         struct btrfs_transaction, list);
1278                 if (!prev_trans->commit_done) {
1279                         atomic_inc(&prev_trans->use_count);
1280                         mutex_unlock(&root->fs_info->trans_mutex);
1281
1282                         wait_for_commit(root, prev_trans);
1283
1284                         mutex_lock(&root->fs_info->trans_mutex);
1285                         put_transaction(prev_trans);
1286                 }
1287         }
1288
1289         if (now < cur_trans->start_time || now - cur_trans->start_time < 1)
1290                 should_grow = 1;
1291
1292         do {
1293                 int snap_pending = 0;
1294                 joined = cur_trans->num_joined;
1295                 if (!list_empty(&trans->transaction->pending_snapshots))
1296                         snap_pending = 1;
1297
1298                 WARN_ON(cur_trans != trans->transaction);
1299                 mutex_unlock(&root->fs_info->trans_mutex);
1300
1301                 if (flush_on_commit || snap_pending) {
1302                         btrfs_start_delalloc_inodes(root, 1);
1303                         ret = btrfs_wait_ordered_extents(root, 0, 1);
1304                         BUG_ON(ret);
1305                 }
1306
1307                 /*
1308                  * rename don't use btrfs_join_transaction, so, once we
1309                  * set the transaction to blocked above, we aren't going
1310                  * to get any new ordered operations.  We can safely run
1311                  * it here and no for sure that nothing new will be added
1312                  * to the list
1313                  */
1314                 btrfs_run_ordered_operations(root, 1);
1315
1316                 prepare_to_wait(&cur_trans->writer_wait, &wait,
1317                                 TASK_UNINTERRUPTIBLE);
1318
1319                 smp_mb();
1320                 if (atomic_read(&cur_trans->num_writers) > 1)
1321                         schedule_timeout(MAX_SCHEDULE_TIMEOUT);
1322                 else if (should_grow)
1323                         schedule_timeout(1);
1324
1325                 mutex_lock(&root->fs_info->trans_mutex);
1326                 finish_wait(&cur_trans->writer_wait, &wait);
1327         } while (atomic_read(&cur_trans->num_writers) > 1 ||
1328                  (should_grow && cur_trans->num_joined != joined));
1329
1330         ret = create_pending_snapshots(trans, root->fs_info);
1331         BUG_ON(ret);
1332
1333         ret = btrfs_run_delayed_refs(trans, root, (unsigned long)-1);
1334         BUG_ON(ret);
1335
1336         WARN_ON(cur_trans != trans->transaction);
1337
1338         /* btrfs_commit_tree_roots is responsible for getting the
1339          * various roots consistent with each other.  Every pointer
1340          * in the tree of tree roots has to point to the most up to date
1341          * root for every subvolume and other tree.  So, we have to keep
1342          * the tree logging code from jumping in and changing any
1343          * of the trees.
1344          *
1345          * At this point in the commit, there can't be any tree-log
1346          * writers, but a little lower down we drop the trans mutex
1347          * and let new people in.  By holding the tree_log_mutex
1348          * from now until after the super is written, we avoid races
1349          * with the tree-log code.
1350          */
1351         mutex_lock(&root->fs_info->tree_log_mutex);
1352
1353         ret = commit_fs_roots(trans, root);
1354         BUG_ON(ret);
1355
1356         /* commit_fs_roots gets rid of all the tree log roots, it is now
1357          * safe to free the root of tree log roots
1358          */
1359         btrfs_free_log_root_tree(trans, root->fs_info);
1360
1361         ret = commit_cowonly_roots(trans, root);
1362         BUG_ON(ret);
1363
1364         btrfs_prepare_extent_commit(trans, root);
1365
1366         cur_trans = root->fs_info->running_transaction;
1367         spin_lock(&root->fs_info->new_trans_lock);
1368         root->fs_info->running_transaction = NULL;
1369         spin_unlock(&root->fs_info->new_trans_lock);
1370
1371         btrfs_set_root_node(&root->fs_info->tree_root->root_item,
1372                             root->fs_info->tree_root->node);
1373         switch_commit_root(root->fs_info->tree_root);
1374
1375         btrfs_set_root_node(&root->fs_info->chunk_root->root_item,
1376                             root->fs_info->chunk_root->node);
1377         switch_commit_root(root->fs_info->chunk_root);
1378
1379         update_super_roots(root);
1380
1381         if (!root->fs_info->log_root_recovering) {
1382                 btrfs_set_super_log_root(&root->fs_info->super_copy, 0);
1383                 btrfs_set_super_log_root_level(&root->fs_info->super_copy, 0);
1384         }
1385
1386         memcpy(&root->fs_info->super_for_commit, &root->fs_info->super_copy,
1387                sizeof(root->fs_info->super_copy));
1388
1389         trans->transaction->blocked = 0;
1390
1391         wake_up(&root->fs_info->transaction_wait);
1392
1393         mutex_unlock(&root->fs_info->trans_mutex);
1394         ret = btrfs_write_and_wait_transaction(trans, root);
1395         BUG_ON(ret);
1396         write_ctree_super(trans, root, 0);
1397
1398         /*
1399          * the super is written, we can safely allow the tree-loggers
1400          * to go about their business
1401          */
1402         mutex_unlock(&root->fs_info->tree_log_mutex);
1403
1404         btrfs_finish_extent_commit(trans, root);
1405
1406         mutex_lock(&root->fs_info->trans_mutex);
1407
1408         cur_trans->commit_done = 1;
1409
1410         root->fs_info->last_trans_committed = cur_trans->transid;
1411
1412         wake_up(&cur_trans->commit_wait);
1413
1414         list_del_init(&cur_trans->list);
1415         put_transaction(cur_trans);
1416         put_transaction(cur_trans);
1417
1418         trace_btrfs_transaction_commit(root);
1419
1420         mutex_unlock(&root->fs_info->trans_mutex);
1421
1422         if (current->journal_info == trans)
1423                 current->journal_info = NULL;
1424
1425         kmem_cache_free(btrfs_trans_handle_cachep, trans);
1426
1427         if (current != root->fs_info->transaction_kthread)
1428                 btrfs_run_delayed_iputs(root);
1429
1430         return ret;
1431 }
1432
1433 /*
1434  * interface function to delete all the snapshots we have scheduled for deletion
1435  */
1436 int btrfs_clean_old_snapshots(struct btrfs_root *root)
1437 {
1438         LIST_HEAD(list);
1439         struct btrfs_fs_info *fs_info = root->fs_info;
1440
1441         mutex_lock(&fs_info->trans_mutex);
1442         list_splice_init(&fs_info->dead_roots, &list);
1443         mutex_unlock(&fs_info->trans_mutex);
1444
1445         while (!list_empty(&list)) {
1446                 root = list_entry(list.next, struct btrfs_root, root_list);
1447                 list_del(&root->root_list);
1448
1449                 if (btrfs_header_backref_rev(root->node) <
1450                     BTRFS_MIXED_BACKREF_REV)
1451                         btrfs_drop_snapshot(root, NULL, 0);
1452                 else
1453                         btrfs_drop_snapshot(root, NULL, 1);
1454         }
1455         return 0;
1456 }