blk-mq: fix queue reference leak on blk_mq_alloc_disk_for_queue failure

Drop the request queue reference just acquired when __alloc_disk_node
failed.

Fixes: 6f8191fdf41d ("block: simplify disk shutdown")
Reported-by: Al Viro <viro@zeniv.linux.org.uk>
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Damien Le Moal <damien.lemoal@opensource.wdc.com>
Link: https://lore.kernel.org/r/20221122072753.426077-1-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

diff --git a/block/blk-mq.c b/block/blk-mq.c
index 6a789cd..228a669 100644 (file)
--- a/block/blk-mq.c
+++ b/block/blk-mq.c
@@ -4045,9 +4045,14 @@ EXPORT_SYMBOL(__blk_mq_alloc_disk);
 struct gendisk *blk_mq_alloc_disk_for_queue(struct request_queue *q,
                struct lock_class_key *lkclass)
 {
+       struct gendisk *disk;
+
        if (!blk_get_queue(q))
                return NULL;
-       return __alloc_disk_node(q, NUMA_NO_NODE, lkclass);
+       disk = __alloc_disk_node(q, NUMA_NO_NODE, lkclass);
+       if (!disk)
+               blk_put_queue(q);
+       return disk;
 }
 EXPORT_SYMBOL(blk_mq_alloc_disk_for_queue);