mtd_blkdevs: use blk_mq_alloc_disk

Use the blk_mq_alloc_disk API 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/20210602065345.355274-10-hch@lst.de
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/mtd/mtd_blkdevs.c

@@ -30,11 +30,9 @@ static void blktrans_dev_release(struct kref *kref)
 	struct mtd_blktrans_dev *dev =
 		container_of(kref, struct mtd_blktrans_dev, ref);
 
-	dev->disk->private_data = NULL;
-	blk_cleanup_queue(dev->rq);
+	blk_cleanup_disk(dev->disk);
 	blk_mq_free_tag_set(dev->tag_set);
 	kfree(dev->tag_set);
-	put_disk(dev->disk);
 	list_del(&dev->list);
 	kfree(dev);
 }
@@ -354,7 +352,7 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 	if (new->devnum > (MINORMASK >> tr->part_bits) ||
 	    (tr->part_bits && new->devnum >= 27 * 26)) {
 		mutex_unlock(&blktrans_ref_mutex);
-		goto error1;
+		return ret;
 	}
 
 	list_add_tail(&new->list, &tr->devs);
@@ -366,17 +364,28 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 	if (!tr->writesect)
 		new->readonly = 1;
 
-	/* Create gendisk */
 	ret = -ENOMEM;
-	gd = alloc_disk(1 << tr->part_bits);
+	new->tag_set = kzalloc(sizeof(*new->tag_set), GFP_KERNEL);
+	if (!new->tag_set)
+		goto out_list_del;
 
-	if (!gd)
-		goto error2;
+	ret = blk_mq_alloc_sq_tag_set(new->tag_set, &mtd_mq_ops, 2,
+			BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING);
+	if (ret)
+		goto out_kfree_tag_set;
+
+	/* Create gendisk */
+	gd = blk_mq_alloc_disk(new->tag_set, new);
+	if (IS_ERR(gd)) {
+		ret = PTR_ERR(gd);
+		goto out_free_tag_set;
+	}
 
 	new->disk = gd;
 	gd->private_data = new;
 	gd->major = tr->major;
 	gd->first_minor = (new->devnum) << tr->part_bits;
+	gd->minors = 1 << tr->part_bits;
 	gd->fops = &mtd_block_ops;
 
 	if (tr->part_bits)
@@ -398,22 +407,9 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 	spin_lock_init(&new->queue_lock);
 	INIT_LIST_HEAD(&new->rq_list);
 
-	new->tag_set = kzalloc(sizeof(*new->tag_set), GFP_KERNEL);
-	if (!new->tag_set)
-		goto error3;
-
-	new->rq = blk_mq_init_sq_queue(new->tag_set, &mtd_mq_ops, 2,
-				BLK_MQ_F_SHOULD_MERGE | BLK_MQ_F_BLOCKING);
-	if (IS_ERR(new->rq)) {
-		ret = PTR_ERR(new->rq);
-		new->rq = NULL;
-		goto error4;
-	}
-
 	if (tr->flush)
 		blk_queue_write_cache(new->rq, true, false);
 
-	new->rq->queuedata = new;
 	blk_queue_logical_block_size(new->rq, tr->blksize);
 
 	blk_queue_flag_set(QUEUE_FLAG_NONROT, new->rq);
@@ -437,13 +433,13 @@ int add_mtd_blktrans_dev(struct mtd_blktrans_dev *new)
 		WARN_ON(ret);
 	}
 	return 0;
-error4:
+
+out_free_tag_set:
+	blk_mq_free_tag_set(new->tag_set);
+out_kfree_tag_set:
 	kfree(new->tag_set);
-error3:
-	put_disk(new->disk);
-error2:
+out_list_del:
 	list_del(&new->list);
-error1:
 	return ret;
 }