dm thin: fix to consistently zero-fill reads to unprovisioned blocks
authorJoe Thornber <ejt@redhat.com>
Fri, 27 Feb 2015 14:09:12 +0000 (14:09 +0000)
committerMike Snitzer <snitzer@redhat.com>
Fri, 27 Feb 2015 14:59:12 +0000 (09:59 -0500)
commit5f027a3bf184d1d36e68745f7cd3718a8b879cc0
treee20a70437603a46f5dbf98474ba03ada49ea9e4a
parentc517d838eb7d07bbe9507871fab3931deccff539
dm thin: fix to consistently zero-fill reads to unprovisioned blocks

It was always intended that a read to an unprovisioned block will return
zeroes regardless of whether the pool is in read-only or read-write
mode.  thin_bio_map() was inconsistent with its handling of such reads
when the pool is in read-only mode, it now properly zero-fills the bios
it returns in response to unprovisioned block reads.

Eliminate thin_bio_map()'s special read-only mode handling of -ENODATA
and just allow the IO to be deferred to the worker which will result in
pool->process_bio() handling the IO (which already properly zero-fills
reads to unprovisioned blocks).

Reported-by: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
drivers/md/dm-thin.c