md: check the return of mddev_find()

Check the return of mddev_find(), since it may fail due to out of
memeory or out of usable minor number.

The reason I chose -ENODEV instead of -ENOMEM or something else is
md_alloc() function chose that ;)

Signed-off-by: Yuanhan Liu <yuanhan.liu@linux.intel.com>
Signed-off-by: NeilBrown <neilb@suse.de>

1 files changed, 3 insertions, 0 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index 4c9836885d3e..1c2f9048e1ae 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -6618,6 +6618,9 @@ static int md_open(struct block_device *bdev, fmode_t mode)
         struct mddev *mddev = mddev_find(bdev->bd_dev);
         int err;
 
+        if (!mddev)
+                return -ENODEV;
+
         if (mddev->gendisk != bdev->bd_disk) {
                 /* we are racing with mddev_put which is discarding this
                  * bd_disk.