block: release rq qos structures for queue without disk

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: block: release rq qos structures for queue without disk blkcg_init_queue() may add rq qos structures to request queue, previously blk_cleanup_queue() calls rq_qos_exit() to release them, but commit 8e141f9eb803 ("block: drain file system I/O on del_gendisk") moves rq_qos_exit() into del_gendisk(), so memory leak is caused because queues may not have disk, such as un-present scsi luns, nvme admin queue, ... Fixes the issue by adding rq_qos_exit() to blk_cleanup_queue() back. BTW, v5.18 won't need this patch any more since we move blkcg_init_queue()/blkcg_exit_queue() into disk allocation/release handler, and patches have been in for-5.18/block.

References

• https://git.kernel.org/stable/c/d4ad8736ac982111bb0be8306bf19c8207f6600e
• https://git.kernel.org/stable/c/60c2c8e2ef3a3ec79de8cbc80a06ca0c21df8c29
• https://git.kernel.org/stable/c/daaca3522a8e67c46e39ef09c1d542e866f85f3b