verify-block-bitmap-even-after-fresh-initialization

   1 ext4: verify block bitmap even after fresh initialization
   2
   3 From: Lukas Czerner <lczerner@redhat.com>
   4
   5 If we want to rely on the buffer_verified() flag of the block bitmap
   6 buffer, we have to set it consistently. However currently if we're
   7 initializing uninitialized block bitmap in
   8 ext4_read_block_bitmap_nowait() we're not going to set buffer verified
   9 at all.
  10
  11 We can do this by simply setting the flag on the buffer, but I think
  12 it's actually better to run ext4_validate_block_bitmap() to make sure
  13 that what we did in the ext4_init_block_bitmap() is right.
  14
  15 So run ext4_validate_block_bitmap() even after the block bitmap
  16 initialization. Also bail out early from ext4_validate_block_bitmap() if
  17 we see corrupt bitmap, since we already know it's corrupt and we do not
  18 need to verify that.
  19
  20 Signed-off-by: Lukas Czerner <lczerner@redhat.com>
  21 Signed-off-by: Theodore Ts'o <tytso@mit.edu>
  22 ---
  23 v2: nothing changed
  24 v3: nothing changed
  25
  26  fs/ext4/balloc.c | 4 ++--
  27  1 file changed, 2 insertions(+), 2 deletions(-)
  28
  29 diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
  30 index 955bf49..cd6ea29 100644
  31 --- a/fs/ext4/balloc.c
  32 +++ b/fs/ext4/balloc.c
  33 @@ -369,7 +369,7 @@ static void ext4_validate_block_bitmap(struct super_block *sb,
  34         struct ext4_group_info *grp = ext4_get_group_info(sb, block_group);
  35         struct ext4_sb_info *sbi = EXT4_SB(sb);
  36
  37 -       if (buffer_verified(bh))
  38 +       if (buffer_verified(bh) || EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
  39                 return;
  40
  41         ext4_lock_group(sb, block_group);
  42 @@ -446,7 +446,7 @@ ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
  43                 unlock_buffer(bh);
  44                 if (err)
  45                         ext4_error(sb, "Checksum bad for grp %u", block_group);
  46 -               return bh;
  47 +               goto verify;
  48         }
  49         ext4_unlock_group(sb, block_group);
  50         if (buffer_uptodate(bh)) {
  51 --
  52 1.8.3.1
  53
  54 --
  55 To unsubscribe from this list: send the line "unsubscribe linux-ext4" in
  56 the body of a message to majordomo@vger.kernel.org
  57 More majordomo info at  http://vger.kernel.org/majordomo-info.html
  58