blkcg: fix gendisk reference leak in blkg_conf_prep()

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@kernel.org>
Cc: stable@vger.kernel.org
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 5 insertions, 1 deletions

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 9da02c021ebe..d6283b3f5db5 100644
--- a/block/blk-cgroup.c
+++ b/block/blk-cgroup.c
@@ -718,8 +718,12 @@ 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);