[3.13.y-ckt stable] Patch "blkcg: fix gendisk reference leak in blkg_conf_prep()" has been added to staging queue

[Kamal Mostafa]

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

    blkcg: fix gendisk reference leak in blkg_conf_prep()

to the linux-3.13.y-queue branch of the 3.13.y-ckt extended stable tree 
which can be found at:

    http://kernel.ubuntu.com/git/ubuntu/linux.git/log/?h=linux-3.13.y-queue

This patch is scheduled to be released in version 3.13.11-ckt26.

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

For more information about the 3.13.y-ckt tree, see
https://wiki.ubuntu.com/Kernel/Dev/ExtendedStable

Thanks.
-Kamal

------

>From ee18dbe1dbce5275894648487535a7c4d39cc185 Mon Sep 17 00:00:00 2001
From: Tejun Heo <tj at kernel.org>
Date: Wed, 22 Jul 2015 18:05:53 -0400
Subject: blkcg: fix gendisk reference leak in blkg_conf_prep()

commit 5f6c2d2b7dbb541c1e922538c49fa04c494ae3d7 upstream.

When a blkcg configuration is targeted to a partition rather than a
whole device, blkg_conf_prep fails with -EINVAL; unfortunately, it
forgets to put the gendisk ref in that case.  Fix it.

Signed-off-by: Tejun Heo <tj at kernel.org>
Signed-off-by: Jens Axboe <axboe at fb.com>
Signed-off-by: Kamal Mostafa <kamal at canonical.com>
---
 block/blk-cgroup.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index d8f80e7..a717585 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -703,8 +703,12 @@ int blkg_conf_prep(struct blkcg *blkcg, const struct blkcg_policy *pol,
 		return -EINVAL;

 	disk = get_gendisk(MKDEV(major, minor), &part);
-	if (!disk || part)
+	if (!disk)
 		return -EINVAL;
+	if (part) {
+		put_disk(disk);
+		return -EINVAL;
+	}

 	rcu_read_lock();
 	spin_lock_irq(disk->queue->queue_lock);
--
1.9.1