[PATCH v2] xfs: make log devices with write back caches work

[Alex Elder]

On Thu, 2011-06-16 at 08:02 -0400, Christoph Hellwig wrote:
> There's no reason not to support cache flushing on external log devices.
> The only thing this really requires is flushing the data device first
> both in fsync and log commits.  A side effect is that we also have to
> remove the barrier write test during mount, which has been superflous
> since the new FLUSH+FUA code anyway.  Also use the chance to flush the
> RT subvolume write cache before the fsync commit, which is required
> for correct semantics.
> 
> Signed-off-by: Christoph Hellwig <hch at lst.de>

Thanks for the explanations and update.  This looks good.
I'm testing now and barring a problem should be to Linus
this weekend.

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