nbd: blk_mq_init_queue returns an error code on failure, not NULL

Additionally, don't assign directly to disk->queue, otherwise
blk_put_queue (called via put_disk) will choke (panic) on the errno
stored there.

Bug found by code inspection after Omar found a similar issue in
virtio_blk.  Compile-tested only.

Signed-off-by: Jeff Moyer <jmoyer@redhat.com>
Reviewed-by: Omar Sandoval <osandov@fb.com>
Reviewed-by: Josef Bacik <jbacik@fb.com>
Signed-off-by: Jens Axboe <axboe@fb.com>

1 files changed, 4 insertions, 2 deletions

diff --git a/drivers/block/nbd.c b/drivers/block/nbd.c
index 38c576f76d36..50a2020b5b72 100644
--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -1042,6 +1042,7 @@ static int __init nbd_init(void)
                 return -ENOMEM;
 
         for (i = 0; i < nbds_max; i++) {
+                struct request_queue *q;
                 struct gendisk *disk = alloc_disk(1 << part_shift);
                 if (!disk)
                         goto out;
@@ -1067,12 +1068,13 @@ static int __init nbd_init(void)
                  * every gendisk to have its very own request_queue struct.
                  * These structs are big so we dynamically allocate them.
                  */
-                disk->queue = blk_mq_init_queue(&nbd_dev[i].tag_set);
-                if (!disk->queue) {
+                q = blk_mq_init_queue(&nbd_dev[i].tag_set);
+                if (IS_ERR(q)) {
                         blk_mq_free_tag_set(&nbd_dev[i].tag_set);
                         put_disk(disk);
                         goto out;
                 }
+                disk->queue = q;
 
                 /*
                  * Tell the block layer that we are not a rotational device