xen-blkfront: 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/20210602065345.355274-26-hch@lst.deSigned-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/xen-blkfront.c

@@ -968,48 +968,6 @@ static void blkif_set_queue_limits(struct blkfront_info *info)
 	blk_queue_dma_alignment(rq, 511);
 }
 
-static int xlvbd_init_blk_queue(struct gendisk *gd, u16 sector_size,
-				unsigned int physical_sector_size)
-{
-	struct request_queue *rq;
-	struct blkfront_info *info = gd->private_data;
-
-	memset(&info->tag_set, 0, sizeof(info->tag_set));
-	info->tag_set.ops = &blkfront_mq_ops;
-	info->tag_set.nr_hw_queues = info->nr_rings;
-	if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
-		/*
-		 * When indirect descriptior is not supported, the I/O request
-		 * will be split between multiple request in the ring.
-		 * To avoid problems when sending the request, divide by
-		 * 2 the depth of the queue.
-		 */
-		info->tag_set.queue_depth =  BLK_RING_SIZE(info) / 2;
-	} else
-		info->tag_set.queue_depth = BLK_RING_SIZE(info);
-	info->tag_set.numa_node = NUMA_NO_NODE;
-	info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
-	info->tag_set.cmd_size = sizeof(struct blkif_req);
-	info->tag_set.driver_data = info;
-
-	if (blk_mq_alloc_tag_set(&info->tag_set))
-		return -EINVAL;
-	rq = blk_mq_init_queue(&info->tag_set);
-	if (IS_ERR(rq)) {
-		blk_mq_free_tag_set(&info->tag_set);
-		return PTR_ERR(rq);
-	}
-
-	rq->queuedata = info;
-	info->rq = gd->queue = rq;
-	info->gd = gd;
-	info->sector_size = sector_size;
-	info->physical_sector_size = physical_sector_size;
-	blkif_set_queue_limits(info);
-
-	return 0;
-}
-
 static const char *flush_info(struct blkfront_info *info)
 {
 	if (info->feature_flush && info->feature_fua)
@@ -1146,12 +1104,36 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
 
 	err = xlbd_reserve_minors(minor, nr_minors);
 	if (err)
-		goto out;
+		return err;
 	err = -ENODEV;
 
-	gd = alloc_disk(nr_minors);
-	if (gd == NULL)
-		goto release;
+	memset(&info->tag_set, 0, sizeof(info->tag_set));
+	info->tag_set.ops = &blkfront_mq_ops;
+	info->tag_set.nr_hw_queues = info->nr_rings;
+	if (HAS_EXTRA_REQ && info->max_indirect_segments == 0) {
+		/*
+		 * When indirect descriptior is not supported, the I/O request
+		 * will be split between multiple request in the ring.
+		 * To avoid problems when sending the request, divide by
+		 * 2 the depth of the queue.
+		 */
+		info->tag_set.queue_depth =  BLK_RING_SIZE(info) / 2;
+	} else
+		info->tag_set.queue_depth = BLK_RING_SIZE(info);
+	info->tag_set.numa_node = NUMA_NO_NODE;
+	info->tag_set.flags = BLK_MQ_F_SHOULD_MERGE;
+	info->tag_set.cmd_size = sizeof(struct blkif_req);
+	info->tag_set.driver_data = info;
+
+	err = blk_mq_alloc_tag_set(&info->tag_set);
+	if (err)
+		goto out_release_minors;
+
+	gd = blk_mq_alloc_disk(&info->tag_set, info);
+	if (IS_ERR(gd)) {
+		err = PTR_ERR(gd);
+		goto out_free_tag_set;
+	}
 
 	strcpy(gd->disk_name, DEV_NAME);
 	ptr = encode_disk_name(gd->disk_name + sizeof(DEV_NAME) - 1, offset);
@@ -1164,14 +1146,16 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
 
 	gd->major = XENVBD_MAJOR;
 	gd->first_minor = minor;
+	gd->minors = nr_minors;
 	gd->fops = &xlvbd_block_fops;
 	gd->private_data = info;
 	set_capacity(gd, capacity);
 
-	if (xlvbd_init_blk_queue(gd, sector_size, physical_sector_size)) {
-		del_gendisk(gd);
-		goto release;
-	}
+	info->rq = gd->queue;
+	info->gd = gd;
+	info->sector_size = sector_size;
+	info->physical_sector_size = physical_sector_size;
+	blkif_set_queue_limits(info);
 
 	xlvbd_flush(info);
 
@@ -1186,9 +1170,10 @@ static int xlvbd_alloc_gendisk(blkif_sector_t capacity,
 
 	return 0;
 
- release:
+out_free_tag_set:
+	blk_mq_free_tag_set(&info->tag_set);
+out_release_minors:
 	xlbd_release_minors(minor, nr_minors);
- out:
 	return err;
 }
 
@@ -1217,12 +1202,9 @@ static void xlvbd_release_gendisk(struct blkfront_info *info)
 	nr_minors = info->gd->minors;
 	xlbd_release_minors(minor, nr_minors);
 
-	blk_cleanup_queue(info->rq);
-	blk_mq_free_tag_set(&info->tag_set);
-	info->rq = NULL;
-
-	put_disk(info->gd);
+	blk_cleanup_disk(info->gd);
 	info->gd = NULL;
+	blk_mq_free_tag_set(&info->tag_set);
 }
 
 /* Already hold rinfo->ring_lock. */