linux-kernel - [PATCH 3.10 039/143] md/raid5: Compare apples to apples (or sectors to sectors)

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Message-Id: <1465122046-9645-40-git-send-email-w@1wt.eu>
Date:	Sun,  5 Jun 2016 12:19:02 +0200
From:	Willy Tarreau <w@....eu>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
Cc:	Jes Sorensen <Jes.Sorensen@...hat.com>,
	stable@...r.kernel.orgv3.7+, Shaohua Li <shli@...com>,
	Willy Tarreau <w@....eu>
Subject: [PATCH 3.10 039/143] md/raid5: Compare apples to apples (or sectors to sectors)

From: Jes Sorensen <Jes.Sorensen@...hat.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")
Cc: stable@...r.kernel.org v3.7+
Signed-off-by: Jes Sorensen <Jes.Sorensen@...hat.com>
Signed-off-by: Shaohua Li <shli@...com>
Signed-off-by: Willy Tarreau <w@....eu>
---
 drivers/md/raid5.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c
index ef18ca7..9ee3c46 100644
--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -5658,8 +5658,8 @@ 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
-- 
2.8.0.rc2.1.gbe9624a