ubi: 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/20210602065345.355274-27-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/mtd/ubi/block.c

@@ -394,28 +394,6 @@ int ubiblock_create(struct ubi_volume_info *vi)
 	dev->vol_id = vi->vol_id;
 	dev->leb_size = vi->usable_leb_size;
 
-	/* Initialize the gendisk of this ubiblock device */
-	gd = alloc_disk(1);
-	if (!gd) {
-		pr_err("UBI: block: alloc_disk failed\n");
-		ret = -ENODEV;
-		goto out_free_dev;
-	}
-
-	gd->fops = &ubiblock_ops;
-	gd->major = ubiblock_major;
-	gd->first_minor = idr_alloc(&ubiblock_minor_idr, dev, 0, 0, GFP_KERNEL);
-	if (gd->first_minor < 0) {
-		dev_err(disk_to_dev(gd),
-			"block: dynamic minor allocation failed");
-		ret = -ENODEV;
-		goto out_put_disk;
-	}
-	gd->private_data = dev;
-	sprintf(gd->disk_name, "ubiblock%d_%d", dev->ubi_num, dev->vol_id);
-	set_capacity(gd, disk_capacity);
-	dev->gd = gd;
-
 	dev->tag_set.ops = &ubiblock_mq_ops;
 	dev->tag_set.queue_depth = 64;
 	dev->tag_set.numa_node = NUMA_NO_NODE;
@@ -427,19 +405,34 @@ int ubiblock_create(struct ubi_volume_info *vi)
 	ret = blk_mq_alloc_tag_set(&dev->tag_set);
 	if (ret) {
 		dev_err(disk_to_dev(dev->gd), "blk_mq_alloc_tag_set failed");
-		goto out_remove_minor;
+		goto out_free_dev;;
 	}
 
-	dev->rq = blk_mq_init_queue(&dev->tag_set);
-	if (IS_ERR(dev->rq)) {
-		dev_err(disk_to_dev(gd), "blk_mq_init_queue failed");
-		ret = PTR_ERR(dev->rq);
+
+	/* Initialize the gendisk of this ubiblock device */
+	gd = blk_mq_alloc_disk(&dev->tag_set, dev);
+	if (IS_ERR(gd)) {
+		ret = PTR_ERR(gd);
 		goto out_free_tags;
 	}
-	blk_queue_max_segments(dev->rq, UBI_MAX_SG_COUNT);
 
-	dev->rq->queuedata = dev;
-	dev->gd->queue = dev->rq;
+	gd->fops = &ubiblock_ops;
+	gd->major = ubiblock_major;
+	gd->minors = 1;
+	gd->first_minor = idr_alloc(&ubiblock_minor_idr, dev, 0, 0, GFP_KERNEL);
+	if (gd->first_minor < 0) {
+		dev_err(disk_to_dev(gd),
+			"block: dynamic minor allocation failed");
+		ret = -ENODEV;
+		goto out_cleanup_disk;
+	}
+	gd->private_data = dev;
+	sprintf(gd->disk_name, "ubiblock%d_%d", dev->ubi_num, dev->vol_id);
+	set_capacity(gd, disk_capacity);
+	dev->gd = gd;
+
+	dev->rq = gd->queue;
+	blk_queue_max_segments(dev->rq, UBI_MAX_SG_COUNT);
 
 	/*
 	 * Create one workqueue per volume (per registered block device).
@@ -448,7 +441,7 @@ int ubiblock_create(struct ubi_volume_info *vi)
 	dev->wq = alloc_workqueue("%s", 0, 0, gd->disk_name);
 	if (!dev->wq) {
 		ret = -ENOMEM;
-		goto out_free_queue;
+		goto out_remove_minor;
 	}
 
 	list_add_tail(&dev->list, &ubiblock_devices);
@@ -460,14 +453,12 @@ int ubiblock_create(struct ubi_volume_info *vi)
 	mutex_unlock(&devices_mutex);
 	return 0;
 
-out_free_queue:
-	blk_cleanup_queue(dev->rq);
-out_free_tags:
-	blk_mq_free_tag_set(&dev->tag_set);
 out_remove_minor:
 	idr_remove(&ubiblock_minor_idr, gd->first_minor);
-out_put_disk:
-	put_disk(dev->gd);
+out_cleanup_disk:
+	blk_cleanup_disk(dev->gd);
+out_free_tags:
+	blk_mq_free_tag_set(&dev->tag_set);
 out_free_dev:
 	kfree(dev);
 out_unlock:
@@ -483,11 +474,10 @@ static void ubiblock_cleanup(struct ubiblock *dev)
 	/* Flush pending work */
 	destroy_workqueue(dev->wq);
 	/* Finally destroy the blk queue */
-	blk_cleanup_queue(dev->rq);
-	blk_mq_free_tag_set(&dev->tag_set);
 	dev_info(disk_to_dev(dev->gd), "released");
+	blk_cleanup_disk(dev->gd);
+	blk_mq_free_tag_set(&dev->tag_set);
 	idr_remove(&ubiblock_minor_idr, dev->gd->first_minor);
-	put_disk(dev->gd);
 }
 
 int ubiblock_remove(struct ubi_volume_info *vi)