[PATCH V4 2/4] ublk_drv: fix ublk device leak in case that add_disk fails

[Ming Lei <ming.lei@redhat.com>]

->free_disk is only called after disk is added successfully, so
drop ublk device reference in case of add_disk() failure.

Fixes: 6d9e6dfdf3b2 ("ublk: defer disk allocation")
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Ming Lei <ming.lei@redhat.com>
---
 drivers/block/ublk_drv.c | 5 +++++
 1 file changed, 5 insertions(+)

diff --git a/drivers/block/ublk_drv.c b/drivers/block/ublk_drv.c
index 7ece4c2ef062..ae98e81b21ce 100644
--- a/drivers/block/ublk_drv.c
+++ b/drivers/block/ublk_drv.c
@@ -1190,6 +1190,11 @@ static int ublk_ctrl_start_dev(struct io_uring_cmd *cmd)
 	get_device(&ub->cdev_dev);
 	ret = add_disk(disk);
 	if (ret) {
+		/*
+		 * Has to drop the reference since ->free_disk won't be
+		 * called in case of add_disk failure.
+		 */
+		ublk_put_device(ub);
 		put_disk(disk);
 		goto out_unlock;
 	}
-- 
2.31.1