Re: [PATCH v3 37/49] fs/mpage: convert to bio_for_each_segment_all_sp()

[Christoph Hellwig]

>  	struct bio_vec *bv;
> +	struct bvec_iter_all bia;
>  	int i;
>  
> -	bio_for_each_segment_all(bv, bio, i) {
> +	bio_for_each_segment_all_sp(bv, bio, i, bia) {
>  		struct page *page = bv->bv_page;
>  		page_endio(page, op_is_write(bio_op(bio)),
>  				blk_status_to_errno(bio->bi_status));

Hmm.  Going back to my previous comment about implementing the single
page variants on top of multipage - I wonder if we should simply
do that in the callers, e.g. something like:

	bio_for_each_segment_all(bv, bio, i) {
		bvec_for_each_page(page, bv, j) {
			page_endio(page, op_is_write(bio_op(bio)),
				blk_status_to_errno(bio->bi_status));
		}
	}

with additional helpers to get the length and offset for the page, e.g.

bvec_page_offset(bv, idx)
bvev_page_len(bv, idx)

While this is a little more code in the callers it's a lot easier to
understand.