Commit 09869de5 authored Jun 11, 2014 by Lukas Czerner Committed by Mike Snitzer Jun 11, 2014

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

parent adcc4447

drivers/md/dm-thin.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -3094,7 +3094,8 @@ static void set_discard_limits(struct pool_c pt, struct queue_limits limits)
		*/
		if (pt->adjusted_pf.discard_passdown) {
		data_limits = &bdev_get_queue(pt->data_dev->bdev)->limits;
		limits->discard_granularity = data_limits->discard_granularity;
		limits->discard_granularity = max(data_limits->discard_granularity,
		pool->sectors_per_block << SECTOR_SHIFT);
		} else
		limits->discard_granularity = pool->sectors_per_block << SECTOR_SHIFT;
		}