Patch "md/raid5: Compare apples to apples (or sectors to sectors)" has been added to the 3.14-stable tree

Patch "md/raid5: Compare apples to apples (or sectors to sectors)" has been added to the 3.14-stable tree

[gregkh]

This is a note to let you know that I've just added the patch titled

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

to the 3.14-stable tree which can be found at:
    http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary

The filename of the patch is:
     md-raid5-compare-apples-to-apples-or-sectors-to-sectors.patch
and it can be found in the queue-3.14 subdirectory.

If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@vger.kernel.org> know about it.


>From e7597e69dec59b65c5525db1626b9d34afdfa678 Mon Sep 17 00:00:00 2001
From: Jes Sorensen <Jes.Sorensen@redhat.com>
Date: Tue, 16 Feb 2016 16:44:24 -0500
Subject: md/raid5: Compare apples to apples (or sectors to sectors)

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: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

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

--- a/drivers/md/raid5.c
+++ b/drivers/md/raid5.c
@@ -6166,8 +6166,8 @@ 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


Patches currently in stable-queue which might be from Jes.Sorensen@redhat.com are

queue-3.14/md-raid5-compare-apples-to-apples-or-sectors-to-sectors.patch