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>

diff --git a/block/blk-cgroup.c b/block/blk-cgroup.c
index 9da02c021ebe2ed296cbdf8560d5bbf2ecd1c48f..d6283b3f5db50674d18ae485970f1e24ed44569d 100644 (file)
--- 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);