[PATCH RFC 4/5] block: move bio validation into __bio_split_to_limits

[Christoph Hellwig]

Replying here, but at least the high-level issue applies to the
previous patch as well.

Moving the checking from submit_bio_noacct into __bio_split_to_limits
means that we lose it for bio-based drivers except for the few that
manuall call bio_split_to_limits.  So we'll still need a helper for
them, which could be called just before calling into ->submit_bio.

> -static inline blk_status_t blk_check_zone_append(struct request_queue *q,
> -						 struct bio *bio)
> -{

Keeping a helper for this instead of doing a lot of work in a switch
statements feels nicer.

> -static blk_status_t blk_validate_atomic_write_op_size(struct request_queue *q,
> -						 struct bio *bio)
> -{
> -	if (bio->bi_iter.bi_size > queue_atomic_write_unit_max_bytes(q))
> -		return BLK_STS_INVAL;
> -
> -	if (bio->bi_iter.bi_size % queue_atomic_write_unit_min_bytes(q))
> -		return BLK_STS_INVAL;
> -
> -	return BLK_STS_OK;
> -}

Similar for this one.