nbd: fix queue freeze vs limits lock order

Match the locking order used by the core block code by only freezing
the queue after taking the limits lock using the
queue_limits_commit_update_frozen helper.

This also allows removes the need for the separate __nbd_set_size helper,
so remove it.

Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Ming Lei <ming.lei@redhat.com>
Reviewed-by: Damien Le Moal <dlemoal@kernel.org>
Reviewed-by: Martin K. Petersen <martin.petersen@oracle.com>
Reviewed-by: Nilay Shroff <nilay@linux.ibm.com>
Reviewed-by: Johannes Thumshirn <johannes.thumshirn@wdc.com>
Link: https://lore.kernel.org/r/20250110054726.1499538-9-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

Author: Christoph Hellwig

drivers/block/nbd.c

@@ -327,8 +327,7 @@ static void nbd_mark_nsock_dead(struct nbd_device *nbd, struct nbd_sock *nsock,
 	nsock->sent = 0;
 }
 
-static int __nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
-		loff_t blksize)
+static int nbd_set_size(struct nbd_device *nbd, loff_t bytesize, loff_t blksize)
 {
 	struct queue_limits lim;
 	int error;
@@ -368,7 +367,7 @@ static int __nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
 
 	lim.logical_block_size = blksize;
 	lim.physical_block_size = blksize;
-	error = queue_limits_commit_update(nbd->disk->queue, &lim);
+	error = queue_limits_commit_update_frozen(nbd->disk->queue, &lim);
 	if (error)
 		return error;
 
@@ -379,18 +378,6 @@ static int __nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
 	return 0;
 }
 
-static int nbd_set_size(struct nbd_device *nbd, loff_t bytesize,
-		loff_t blksize)
-{
-	int error;
-
-	blk_mq_freeze_queue(nbd->disk->queue);
-	error = __nbd_set_size(nbd, bytesize, blksize);
-	blk_mq_unfreeze_queue(nbd->disk->queue);
-
-	return error;
-}
-
 static void nbd_complete_rq(struct request *req)
 {
 	struct nbd_cmd *cmd = blk_mq_rq_to_pdu(req);