[3.11.y.z extended stable] Patch "md/raid10: fix two bugs in handling of known-bad-blocks." has been added to staging queue

[Luis Henriques]

This is a note to let you know that I have just added a patch titled

    md/raid10: fix two bugs in handling of known-bad-blocks.

to the linux-3.11.y-queue branch of the 3.11.y.z extended stable tree 
which can be found at:

 http://kernel.ubuntu.com/git?p=ubuntu/linux.git;a=shortlog;h=refs/heads/linux-3.11.y-queue

If you, or anyone else, feels it should not be added to this tree, please 
reply to this email.

For more information about the 3.11.y.z tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Luis

------

>From 08ecec3327e9e268d8cd0db41600f59ce3670121 Mon Sep 17 00:00:00 2001
From: NeilBrown <neilb at suse.de>
Date: Tue, 14 Jan 2014 10:38:09 +1100
Subject: md/raid10: fix two bugs in handling of known-bad-blocks.

commit b50c259e25d9260b9108dc0c2964c26e5ecbe1c1 upstream.

If we discover a bad block when reading we split the request and
potentially read some of it from a different device.

The code path of this has two bugs in RAID10.
1/ we get a spin_lock with _irq, but unlock without _irq!!
2/ The calculation of 'sectors_handled' is wrong, as can be clearly
   seen by comparison with raid1.c

This leads to at least 2 warnings and a probable crash is a RAID10
ever had known bad blocks.

Fixes: 856e08e23762dfb92ffc68fd0a8d228f9e152160
Reported-by: Damian Nowak <spam at nowaker.net>
URL: https://bugzilla.kernel.org/show_bug.cgi?id=68181
Signed-off-by: NeilBrown <neilb at suse.de>
Signed-off-by: Luis Henriques <luis.henriques at canonical.com>
---
 drivers/md/raid10.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/drivers/md/raid10.c b/drivers/md/raid10.c
index 73dc8a3..cc9b777 100644
--- a/drivers/md/raid10.c
+++ b/drivers/md/raid10.c
@@ -1319,7 +1319,7 @@ read_again:
 			/* Could not read all from this device, so we will
 			 * need another r10_bio.
 			 */
-			sectors_handled = (r10_bio->sectors + max_sectors
+			sectors_handled = (r10_bio->sector + max_sectors
 					   - bio->bi_sector);
 			r10_bio->sectors = max_sectors;
 			spin_lock_irq(&conf->device_lock);
@@ -1327,7 +1327,7 @@ read_again:
 				bio->bi_phys_segments = 2;
 			else
 				bio->bi_phys_segments++;
-			spin_unlock(&conf->device_lock);
+			spin_unlock_irq(&conf->device_lock);
 			/* Cannot call generic_make_request directly
 			 * as that will be queued in __generic_make_request
 			 * and subsequent mempool_alloc might block
--
1.8.3.2