releases/2.6.32.17/0028-ext4-Issue-the-discard-operation-before-releasing-th.patch

   1 From 462d9c2b296ce81bf4c6a6899e256ae6188f9a5a Mon Sep 17 00:00:00 2001
   2 From: Theodore Ts'o <tytso@mit.edu>
   3 Date: Sun, 30 May 2010 22:49:42 -0400
   4 Subject: ext4: Issue the discard operation *before* releasing the blocks to be reused
   5
   6 commit b90f687018e6d6c77d981b09203780f7001407e5 upstream (as of v2.6.34-rc6)
   7
   8 Otherwise, we can end up having data corruption because the blocks
   9 could get reused and then discarded!
  10
  11 https://bugzilla.kernel.org/show_bug.cgi?id=15579
  12
  13 Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
  14 Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
  15 ---
  16  fs/ext4/mballoc.c |   24 +++++++++++-------------
  17  1 file changed, 11 insertions(+), 13 deletions(-)
  18
  19 --- a/fs/ext4/mballoc.c
  20 +++ b/fs/ext4/mballoc.c
  21 @@ -2537,6 +2537,17 @@ static void release_blocks_on_commit(jou
  22                 mb_debug(1, "gonna free %u blocks in group %u (0x%p):",
  23                          entry->count, entry->group, entry);
  24
  25 +               if (test_opt(sb, DISCARD)) {
  26 +                       ext4_fsblk_t discard_block;
  27 +
  28 +                       discard_block = entry->start_blk +
  29 +                               ext4_group_first_block_no(sb, entry->group);
  30 +                       trace_ext4_discard_blocks(sb,
  31 +                                       (unsigned long long)discard_block,
  32 +                                       entry->count);
  33 +                       sb_issue_discard(sb, discard_block, entry->count);
  34 +               }
  35 +
  36                 err = ext4_mb_load_buddy(sb, entry->group, &e4b);
  37                 /* we expect to find existing buddy because it's pinned */
  38                 BUG_ON(err != 0);
  39 @@ -2558,19 +2569,6 @@ static void release_blocks_on_commit(jou
  40                         page_cache_release(e4b.bd_bitmap_page);
  41                 }
  42                 ext4_unlock_group(sb, entry->group);
  43 -               if (test_opt(sb, DISCARD)) {
  44 -                       ext4_fsblk_t discard_block;
  45 -                       struct ext4_super_block *es = EXT4_SB(sb)->s_es;
  46 -
  47 -                       discard_block = (ext4_fsblk_t)entry->group *
  48 -                                               EXT4_BLOCKS_PER_GROUP(sb)
  49 -                                       + entry->start_blk
  50 -                                       + le32_to_cpu(es->s_first_data_block);
  51 -                       trace_ext4_discard_blocks(sb,
  52 -                                       (unsigned long long)discard_block,
  53 -                                       entry->count);
  54 -                       sb_issue_discard(sb, discard_block, entry->count);
  55 -               }
  56                 kmem_cache_free(ext4_free_ext_cachep, entry);
  57                 ext4_mb_release_desc(&e4b);
  58         }