> On Jun 1, 2015, at 1:54 AM, Lukas Czerner <lczerner@xxxxxxxxxx> wrote:
>
> If we want to rely on the buffer_verified() flag of the block bitmap
> buffer, we have to set it consistently. However currently if we're
> initializing uninitialized block bitmap in
> ext4_read_block_bitmap_nowait() we're not going to set buffer verified
> at all.
>
> We can do this by simply setting the flag on the buffer, but I think
> it's actually better to run ext4_validate_block_bitmap() to make sure
> that what we did in the ext4_init_block_bitmap() is right.
>
> So run ext4_validate_block_bitmap() even after the block bitmap
> initialization. Also bail out early from ext4_validate_block_bitmap() if
> we see corrupt bitmap, since we already know it's corrupt and we do not
> need to verify that.
>
> Signed-off-by: Lukas Czerner <lczerner@xxxxxxxxxx>
> ---
> fs/ext4/balloc.c | 4 ++--
> 1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/fs/ext4/balloc.c b/fs/ext4/balloc.c
> index 955bf49..cd6ea29 100644
> --- a/fs/ext4/balloc.c
> +++ b/fs/ext4/balloc.c
> @@ -369,7 +369,7 @@ static void ext4_validate_block_bitmap(struct super_block *sb,
> struct ext4_group_info *grp = ext4_get_group_info(sb, block_group);
> struct ext4_sb_info *sbi = EXT4_SB(sb);
>
> - if (buffer_verified(bh))
> + if (buffer_verified(bh) || EXT4_MB_GRP_BBITMAP_CORRUPT(grp))
> return;
>
> ext4_lock_group(sb, block_group);
> @@ -446,7 +446,7 @@ ext4_read_block_bitmap_nowait(struct super_block *sb, ext4_group_t block_group)
> unlock_buffer(bh);
> if (err)
> ext4_error(sb, "Checksum bad for grp %u", block_group);
> - return bh;
> + goto verify;
(defect) This looks like it will miss the ext4_unlock_group() call
below, since that is missing in the "verify:" branch. Either you
need to add an explicit ext4_unlock_group() call before "goto verify",
or add a new "unlock_group:" label that unlocks the group.
> }
> ext4_unlock_group(sb, block_group);
> if (buffer_uptodate(bh)) {
Cheers, Andreas
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