fix-xfstest-generic-269-double-revoked-buffer-bug

   1 ext4: fix xfstest generic/269 double revoked buffer bug with bigalloc
   2
   3 From: Daeho Jeong <daeho.jeong@samsung.com>
   4
   5 When you repeatly execute xfstest generic/269 with bigalloc_1k option
   6 enabled using the below command:
   7
   8 "./kvm-xfstests -c bigalloc_1k -m nodelalloc -C 1000 generic/269"
   9
  10 you can easily see the below bug message.
  11
  12 "JBD2 unexpected failure: jbd2_journal_revoke: !buffer_revoked(bh);"
  13
  14 This means that an already revoked buffer is erroneously revoked again
  15 and it is caused by doing revoke for the buffer at the wrong position
  16 in ext4_free_blocks(). We need to re-position the buffer revoke
  17 procedure for an unspecified buffer after checking the cluster boundary
  18 for bigalloc option. If not, some part of the cluster can be doubly
  19 revoked.
  20
  21 Signed-off-by: Daeho Jeong <daeho.jeong@samsung.com>
  22 ---
  23  fs/ext4/mballoc.c | 32 +++++++++++++++++---------------
  24  1 file changed, 17 insertions(+), 15 deletions(-)
  25
  26 diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c
  27 index cf48581..b4da7f2 100644
  28 --- a/fs/ext4/mballoc.c
  29 +++ b/fs/ext4/mballoc.c
  30 @@ -4686,22 +4686,11 @@ void ext4_free_blocks(handle_t *handle, struct inode *inode,
  31         ext4_debug("freeing block %llu\n", block);
  32         trace_ext4_free_blocks(inode, block, count, flags);
  33
  34 -       if (flags & EXT4_FREE_BLOCKS_FORGET) {
  35 -               struct buffer_head *tbh = bh;
  36 -               int i;
  37 -
  38 -               BUG_ON(bh && (count > 1));
  39 +       if (bh && (flags & EXT4_FREE_BLOCKS_FORGET)) {
  40 +               BUG_ON(count > 1);
  41
  42 -               for (i = 0; i < count; i++) {
  43 -                       cond_resched();
  44 -                       if (!bh)
  45 -                               tbh = sb_find_get_block(inode->i_sb,
  46 -                                                       block + i);
  47 -                       if (!tbh)
  48 -                               continue;
  49 -                       ext4_forget(handle, flags & EXT4_FREE_BLOCKS_METADATA,
  50 -                                   inode, tbh, block + i);
  51 -               }
  52 +               ext4_forget(handle, flags & EXT4_FREE_BLOCKS_METADATA,
  53 +                           inode, bh, block);
  54         }
  55
  56         /*
  57 @@ -4746,6 +4735,19 @@ void ext4_free_blocks(handle_t *handle, struct inode *inode,
  58                         count += sbi->s_cluster_ratio - overflow;
  59         }
  60
  61 +       if (!bh && (flags & EXT4_FREE_BLOCKS_FORGET)) {
  62 +               int i;
  63 +
  64 +               for (i = 0; i < count; i++) {
  65 +                       cond_resched();
  66 +                       bh = sb_find_get_block(inode->i_sb, block + i);
  67 +                       if (!bh)
  68 +                               continue;
  69 +                       ext4_forget(handle, flags & EXT4_FREE_BLOCKS_METADATA,
  70 +                                   inode, bh, block + i);
  71 +               }
  72 +       }
  73 +
  74  do_more:
  75         overflow = 0;
  76         ext4_get_group_no_and_offset(sb, block, &block_group, &bit);