linux-kernel - [PATCH 4.5 161/238] md/raid5: Compare apples to apples (or sectors to sectors)

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Message-Id: <20160410183505.419065060@linuxfoundation.org>
Date:	Sun, 10 Apr 2016 11:35:38 -0700
From:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>
To:	linux-kernel@...r.kernel.org
Cc:	Greg Kroah-Hartman <gregkh@...uxfoundation.org>,
	stable@...r.kernel.org, Jes Sorensen <Jes.Sorensen@...hat.com>,
	Shaohua Li <shli@...com>
Subject: [PATCH 4.5 161/238] md/raid5: Compare apples to apples (or sectors to sectors)

4.5-stable review patch.  If anyone has any objections, please let me know.

------------------

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")
Signed-off-by: Jes Sorensen <Jes.Sorensen@...hat.com>
Signed-off-by: Shaohua Li <shli@...com>
Signed-off-by: Greg Kroah-Hartman <gregkh@...uxfoundation.org>

---
 drivers/md/raid5.c |    4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

--- 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