xfs_scrub: use scrub barriers to reduce kernel calls

Use scrub barriers so that we can submit a single scrub request for a
bunch of things, and have the kernel stop midway through if it finds
anything broken.

Signed-off-by: Darrick J. Wong <djwong@kernel.org>
Reviewed-by: Christoph Hellwig <hch@lst.de>
6 files changed