dm thin: update discard_granularity to reflect the thin-pool blocksize
authorLukas Czerner <lczerner@redhat.com>
Wed, 11 Jun 2014 16:28:43 +0000 (12:28 -0400)
committerMike Snitzer <snitzer@redhat.com>
Wed, 11 Jun 2014 20:56:12 +0000 (16:56 -0400)
commit09869de57ed2728ae3c619803932a86cb0e2c4f8
treeab74c6c4b5a60a374e8544ad32198f916e373db0
parentadcc44472bacb227ebc0b1a8876efa5302474338
dm thin: update discard_granularity to reflect the thin-pool blocksize

DM thinp already checks whether the discard_granularity of the data
device is a factor of the thin-pool block size.  But when using the
dm-thin-pool's discard passdown support, DM thinp was not selecting the
max of the underlying data device's discard_granularity and the
thin-pool's block size.

Update set_discard_limits() to set discard_granularity to the max of
these values.  This enables blkdev_issue_discard() to properly align the
discards that are sent to the DM thin device on a full block boundary.
As such each discard will now cover an entire DM thin-pool block and the
block will be reclaimed.

Reported-by: Zdenek Kabelac <zkabelac@redhat.com>
Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Cc: stable@vger.kernel.org
drivers/md/dm-thin.c