Re: [PATCH 11/14] xfs: remote attribute tail zeroing does too much

Ben Myers
2013-05-20T23:01:25Z

On Mon, May 20, 2013 at 09:51:18AM +1000, Dave Chinner wrote:
> From: Dave Chinner <dchinner@redhat.com>
>
> When an attribute data does not fill then entire remote block, we
> zero the remaining part of the buffer. This, however, needs to take
> into account that the buffer has a header, and so the offset where
> zeroing starts and the length of zeroing need to take this into
> account. Otherwise we end up with zeros over the end of the
> attribute value when CRCs are enabled.
>
> While there, make sure we only ask to map an extent that covers the
> remaining range of the attribute, rather than asking every time for
> the full length of remote data. If the remote attribute blocks are
> contiguous with other parts of the attribute tree, it will map those
> blocks as well and we can potentially zero them incorrectly. We can
> also get buffer size mistmatches when trying to read or remove the
> remote attribute, and this can lead to not finding the correct
> buffer when looking it up in cache.
>
> Signed-off-by: Dave Chinner <dchinner@redhat.com>
> ---
> fs/xfs/xfs_attr_remote.c | 37 ++++++++++++++++++-------------------
> 1 file changed, 18 insertions(+), 19 deletions(-)
>
> diff --git a/fs/xfs/xfs_attr_remote.c b/fs/xfs/xfs_attr_remote.c
> index bcdc07c..e207bf0 100644
> --- a/fs/xfs/xfs_attr_remote.c
> +++ b/fs/xfs/xfs_attr_remote.c
> @@ -296,10 +296,7 @@ xfs_attr_rmtval_set(
> * and we may not need that many, so we have to handle this when
> * allocating the blocks below.
> */
> - if (!crcs)
> - blkcnt = XFS_B_TO_FSB(mp, args->valuelen);
> - else
> - blkcnt = xfs_attr3_rmt_blocks(mp, args->valuelen);
> + blkcnt = xfs_attr3_rmt_blocks(mp, args->valuelen);

Oh. There you have it. Nevermind.