On Wed, Aug 22, 2012 at 08:10:38PM -0600, bo.li.liu@xxxxxxxxxx wrote:
> From: Liu Bo <bo.li.liu@xxxxxxxxxx>
>
> This bug is introduced by commit 3b8bde746f6f9bd36a9f05f5f3b6e334318176a9
> (Btrfs: lock extents as we map them in DIO).
>
> In dio write, we should unlock the section which we didn't do IO on in case that
> we fall back to buffered write. But we need to not only unlock the section
> but also cleanup reserved space for the section.
>
> This bug was found while running xfstests 133, with this 133 no longer complains.
>
> Signed-off-by: Liu Bo <bo.li.liu@xxxxxxxxxx>
> ---
> v1->v2: apply style comments from David Sterba.
>
> fs/btrfs/inode.c | 24 ++++++++++++++++++++----
> 1 files changed, 20 insertions(+), 4 deletions(-)
>
> diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
> index 7131fac..ea6a4ee 100644
> --- a/fs/btrfs/inode.c
> +++ b/fs/btrfs/inode.c
> @@ -5993,11 +5993,27 @@ unlock:
> * in the case of read we need to unlock only the end area that we
> * aren't using if there is any left over space.
> */
> - if (lockstart < lockend)
> - clear_extent_bit(&BTRFS_I(inode)->io_tree, lockstart, lockend,
> - unlock_bits, 1, 0, &cached_state, GFP_NOFS);
> - else
> + if (lockstart < lockend) {
> + if (create && len < lockend - lockstart) {
> + clear_extent_bit(&BTRFS_I(inode)->io_tree, lockstart,
> + lockstart + len - 1, unlock_bits, 1, 0,
> + &cached_state, GFP_NOFS);
> + /*
> + * Beside unlock, we also need to cleanup reserved space
> + * for the left range by attaching EXTENT_DO_ACCOUNTING.
> + */
> + clear_extent_bit(&BTRFS_I(inode)->io_tree,
> + lockstart + len, lockend,
> + unlock_bits | EXTENT_DO_ACCOUNTING,
> + 1, 0, NULL, GFP_NOFS);
> + } else {
> + clear_extent_bit(&BTRFS_I(inode)->io_tree, lockstart,
> + lockend, unlock_bits, 1, 0,
> + &cached_state, GFP_NOFS);
> + }
> + } else {
> free_extent_state(cached_state);
> + }
>
> free_extent_map(em);
>
Ahh yeah good catch, thanks Liu.
Josef
--
To unsubscribe from this list: send the line "unsubscribe linux-btrfs" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
