[PATCH V10 11/19] bcache: avoid to use bio_for_each_segment_all() in bch_bio_alloc_pages()

[Christoph Hellwig]

> -	bio_for_each_segment_all(bv, bio, i) {
> +	for (i = 0, bv = bio->bi_io_vec; i < bio->bi_vcnt; bv++) {

This really needs a comment.  Otherwise it looks fine to me.