[PATCH 5/6] xfs: add online discard support

[Alex Elder]

On Tue, 2011-03-22 at 15:55 -0400, Christoph Hellwig wrote:
> Now that we have reliably tracking of deleted extents in a transaction
> we can easily implement "online" discard support which calls
> blkdev_issue_discard once a transaction commits.
> 
> The actual discard is a two stage operation as we first have to mark
> the busy extent as not available for reuse before we can start the
> actual discard.  Note that we don't bother supporting discard for
> the non-delaylog mode.  While that would be possible with this patch
> performance is awfull, and the optimization in the next patch won't
> work as easily.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>

. . .

This one looks good overall.  How about adding
documentation to Documentation/filesystems/xfs.txt
to describe the new mount options?  (Dave, same
goes for you with delaylog.  I haven't looked for
any other things missing from there.)

Reviewed-by: Alex Elder <aelder at sgi.com>