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[4.2.y-ckt,050/218] md/raid5: Compare apples to apples (or sectors to sectors)

Message ID 1459455431-12687-51-git-send-email-kamal@canonical.com
State New
Headers show

Commit Message

Kamal Mostafa March 31, 2016, 8:14 p.m. UTC 
4.2.8-ckt7 -stable review patch.  If anyone has any objections, please let me know.

---8<------------------------------------------------------------

From: Jes Sorensen <Jes.Sorensen@redhat.com>

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: Kamal Mostafa <kamal@canonical.com>
---
 drivers/md/raid5.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)
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Patch

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index 0d4f7b1..a6917f0 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -6958,8 +6958,8 @@  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