rbd: drop dev reference on error in rbd_open()

If a read-only rbd device is opened for writing in rbd_open(), it
returns without dropping the just-acquired device reference.

Fix this by moving the read-only check before getting the reference.

Signed-off-by: Alex Elder <elder@inktank.com>
Reviewed-by: Yehuda Sadeh <yehuda@inktank.com>
Reviewed-by: Josh Durgin <josh.durgin@inktank.com>
(cherry picked from commit 340c7a2b2c9a2da640af28a8c196356484ac8b50)
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/drivers/block/rbd.c b/drivers/block/rbd.c
index 52e295defb983d19c2a0b56bb619a106e78e18dd..c05a4ab47e5a51616eac7dd4810be8eee63d6dfa 100644 (file)
--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -250,13 +250,12 @@ static int rbd_open(struct block_device *bdev, fmode_t mode)
 {
        struct rbd_device *rbd_dev = bdev->bd_disk->private_data;
 
-       rbd_get_dev(rbd_dev);
-
-       set_device_ro(bdev, rbd_dev->read_only);
-
        if ((mode & FMODE_WRITE) && rbd_dev->read_only)
                return -EROFS;
 
+       rbd_get_dev(rbd_dev);
+       set_device_ro(bdev, rbd_dev->read_only);
+
        return 0;
 }