static inline bool __is_discard_mergeable(struct discard_info *back,
			struct discard_info *front, unsigned int max_len)
{
	return (back->lstart + back->len == front->lstart) &&
		(back->len + front->len <= max_len);
}
static inline bool __is_discard_mergeable(struct discard_info *back,
			struct discard_info *front, unsigned int max_len)
{
	return (back->lstart + back->len == front->lstart) &&
		(back->len + front->len <= max_len);
}