nbd: use blk_mq_alloc_disk and blk_cleanup_disk

Use blk_mq_alloc_disk and blk_cleanup_disk to simplify the gendisk and
request_queue allocation.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Reviewed-by: Chaitanya Kulkarni <chaitanya.kulkarni@wdc.com>
Link: https://lore.kernel.org/r/20210602065345.355274-20-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/nbd.c

@@ -219,15 +219,11 @@ static const struct device_attribute pid_attr = {
 static void nbd_dev_remove(struct nbd_device *nbd)
 {
 	struct gendisk *disk = nbd->disk;
-	struct request_queue *q;
 
 	if (disk) {
-		q = disk->queue;
 		del_gendisk(disk);
-		blk_cleanup_queue(q);
 		blk_mq_free_tag_set(&nbd->tag_set);
-		disk->private_data = NULL;
-		put_disk(disk);
+		blk_cleanup_disk(disk);
 	}
 
 	/*
@@ -1646,15 +1642,24 @@ static int nbd_dev_add(int index)
 {
 	struct nbd_device *nbd;
 	struct gendisk *disk;
-	struct request_queue *q;
 	int err = -ENOMEM;
 
 	nbd = kzalloc(sizeof(struct nbd_device), GFP_KERNEL);
 	if (!nbd)
 		goto out;
 
-	disk = alloc_disk(1 << part_shift);
-	if (!disk)
+	nbd->tag_set.ops = &nbd_mq_ops;
+	nbd->tag_set.nr_hw_queues = 1;
+	nbd->tag_set.queue_depth = 128;
+	nbd->tag_set.numa_node = NUMA_NO_NODE;
+	nbd->tag_set.cmd_size = sizeof(struct nbd_cmd);
+	nbd->tag_set.flags = BLK_MQ_F_SHOULD_MERGE |
+		BLK_MQ_F_BLOCKING;
+	nbd->tag_set.driver_data = nbd;
+	nbd->destroy_complete = NULL;
+
+	err = blk_mq_alloc_tag_set(&nbd->tag_set);
+	if (err)
 		goto out_free_nbd;
 
 	if (index >= 0) {
@@ -1668,30 +1673,15 @@ static int nbd_dev_add(int index)
 			index = err;
 	}
 	if (err < 0)
-		goto out_free_disk;
-
+		goto out_free_tags;
 	nbd->index = index;
-	nbd->disk = disk;
-	nbd->tag_set.ops = &nbd_mq_ops;
-	nbd->tag_set.nr_hw_queues = 1;
-	nbd->tag_set.queue_depth = 128;
-	nbd->tag_set.numa_node = NUMA_NO_NODE;
-	nbd->tag_set.cmd_size = sizeof(struct nbd_cmd);
-	nbd->tag_set.flags = BLK_MQ_F_SHOULD_MERGE |
-		BLK_MQ_F_BLOCKING;
-	nbd->tag_set.driver_data = nbd;
-	nbd->destroy_complete = NULL;
 
-	err = blk_mq_alloc_tag_set(&nbd->tag_set);
-	if (err)
+	disk = blk_mq_alloc_disk(&nbd->tag_set, NULL);
+	if (IS_ERR(disk)) {
+		err = PTR_ERR(disk);
 		goto out_free_idr;
-
-	q = blk_mq_init_queue(&nbd->tag_set);
-	if (IS_ERR(q)) {
-		err = PTR_ERR(q);
-		goto out_free_tags;
 	}
-	disk->queue = q;
+	nbd->disk = disk;
 
 	/*
 	 * Tell the block layer that we are not a rotational device
@@ -1712,6 +1702,7 @@ static int nbd_dev_add(int index)
 	INIT_LIST_HEAD(&nbd->list);
 	disk->major = NBD_MAJOR;
 	disk->first_minor = index << part_shift;
+	disk->minors = 1 << part_shift;
 	disk->fops = &nbd_fops;
 	disk->private_data = nbd;
 	sprintf(disk->disk_name, "nbd%d", index);
@@ -1719,12 +1710,10 @@ static int nbd_dev_add(int index)
 	nbd_total_devices++;
 	return index;
 
-out_free_tags:
-	blk_mq_free_tag_set(&nbd->tag_set);
 out_free_idr:
 	idr_remove(&nbd_index_idr, index);
-out_free_disk:
-	put_disk(disk);
+out_free_tags:
+	blk_mq_free_tag_set(&nbd->tag_set);
 out_free_nbd:
 	kfree(nbd);
 out: