Almost all callers of add_gendisk() were immediately followed by
register_disk(disk, mk_kdev(disk->major,disk->first_minor),
	      1<<disk->minor_shift, disk->fops, something);
The only exception (DAC960.c) massaged to that form.
New helper (add_disk(disk)) introduced and aforementioned sequence
replaced with
	set_capacity(disk, something);
	add_disk(disk);