null_blk: cleanup null_gendisk_register

Use a saner size calculation, and do a trivial cleanup on the zone
revalidation to prepare to future changes.
Signed-off-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Jens Axboe <axboe@kernel.dk>

drivers/block/null_blk_main.c

@@ -1559,14 +1559,14 @@ static int init_driver_queues(struct nullb *nullb)
 
 static int null_gendisk_register(struct nullb *nullb)
 {
+	sector_t size = ((sector_t)nullb->dev->size * SZ_1M) >> SECTOR_SHIFT;
 	struct gendisk *disk;
-	sector_t size;
+	int ret;
 
 	disk = nullb->disk = alloc_disk_node(1, nullb->dev->home_node);
 	if (!disk)
 		return -ENOMEM;
-	size = (sector_t)nullb->dev->size * 1024 * 1024ULL;
-	set_capacity(disk, size >> 9);
+	set_capacity(disk, size);
 
 	disk->flags |= GENHD_FL_EXT_DEVT | GENHD_FL_SUPPRESS_PARTITION_INFO;
 	disk->major		= null_major;
@@ -1577,9 +1577,8 @@ static int null_gendisk_register(struct nullb *nullb)
 	strncpy(disk->disk_name, nullb->disk_name, DISK_NAME_LEN);
 
 	if (nullb->dev->zoned) {
-		int ret = blk_revalidate_disk_zones(disk);
-
-		if (ret != 0)
+		ret = blk_revalidate_disk_zones(disk);
+		if (ret)
 			return ret;
 	}