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

'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")
Cc: [email protected] v3.7+
Signed-off-by: Jes Sorensen <[email protected]>
Signed-off-by: Shaohua Li <[email protected]>

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index b4f02c9959f23c1bb5e8feccb2b9bf6e1c59e862..7f770b0c0348ce5fce1700be900e68e35f967f55 100644 (file)
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -7014,8 +7014,8 @@ static int raid5_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