md/raid5: Compare apples to apples (or sectors to sectors)

commit e7597e69dec59b65c5525db1626b9d34afdfa678 upstream.

'max_discard_sectors' is in sectors, while 'stripe' is in bytes.

This fixes the problem where DISCARD would get disabled on some larger
RAID5 configurations (6 or more drives in my testing), while it worked
as expected with smaller configurations.

Fixes: 620125f2bf8 ("MD: raid5 trim support")
Signed-off-by: Jes Sorensen <Jes.Sorensen@redhat.com>
Signed-off-by: Shaohua Li <shli@fb.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index f90752ce95dc8a1f5366f4b891b2381ab80b8a2e..9d9d757a3488ed0c6b0862c29b4d07c0e8276517 100644 (file)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -6264,8 +6264,8 @@ static int run(struct mddev *mddev)
                }
 
                if (discard_supported &&
-                  mddev->queue->limits.max_discard_sectors >= stripe &&
-                  mddev->queue->limits.discard_granularity >= stripe)
+                   mddev->queue->limits.max_discard_sectors >= (stripe >> 9) &&
+                   mddev->queue->limits.discard_granularity >= stripe)
                        queue_flag_set_unlocked(QUEUE_FLAG_DISCARD,
                                                mddev->queue);
                else