[ 140/171] rbd: drop dev reference on error in rbd_open()

[Greg Kroah-Hartman]

3.4-stable review patch.  If anyone has any objections, please let me know.

------------------


From: Alex Elder <elder@xxxxxxxxxxx>

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@xxxxxxxxxxx>
Reviewed-by: Yehuda Sadeh <yehuda@xxxxxxxxxxx>
Reviewed-by: Josh Durgin <josh.durgin@xxxxxxxxxxx>
(cherry picked from commit 340c7a2b2c9a2da640af28a8c196356484ac8b50)
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
 drivers/block/rbd.c |    7 +++----
 1 file changed, 3 insertions(+), 4 deletions(-)

--- a/drivers/block/rbd.c
+++ b/drivers/block/rbd.c
@@ -250,13 +250,12 @@ static int rbd_open(struct block_device
 {
 	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;
 }
 


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