md/raid5: round discard alignment up to power of 2.
blkdev_issue_discard currently assumes that the granularity
is a power of 2. So in raid5, round the chosen number up to
avoid embarrassment.
Cc: Shaohua Li <shli@kernel.org>
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index c5439dc..baea94f 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5529,6 +5529,10 @@
* discard data disk but write parity disk
*/
stripe = stripe * PAGE_SIZE;
+ /* Round up to power of 2, as discard handling
+ * currently assumes that */
+ while ((stripe-1) & stripe)
+ stripe = (stripe | (stripe-1)) + 1;
mddev->queue->limits.discard_alignment = stripe;
mddev->queue->limits.discard_granularity = stripe;
/*