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

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

From: Jeff Moyer <jmo...@redhat.com>


[ Upstream commit 25b4acfc7de0fc4da3bfea3a316f7282c6fbde81 ]

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 <jmo...@redhat.com>
Reviewed-by: Omar Sandoval <osan...@fb.com>
Reviewed-by: Josef Bacik <jba...@fb.com>
Signed-off-by: Jens Axboe <ax...@fb.com>
Signed-off-by: Sasha Levin <alexander.le...@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gre...@linuxfoundation.org>
---
 drivers/block/nbd.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

--- a/drivers/block/nbd.c
+++ b/drivers/block/nbd.c
@@ -929,6 +929,7 @@ 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;
@@ -954,12 +955,13 @@ 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


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