bvec_iter_advance_single
bvec_iter_advance_single(iter->bvecs, &iter->iter, bv.bv_len);
bvec_iter_advance_single(iter->bvecs, &iter->iter, next.bv_len);
bvec_iter_advance_single(bvecs, iter, bv.bv_len);
bvec_iter_advance_single(bio->bi_io_vec, iter, bytes);
bvec_iter_advance_single((bio_vec), &(iter), (bvl).bv_len))
bvec_iter_advance_single((bio_vec), &(iter), (bvl).bv_len))
bvec_iter_advance_single(from->bvec, &bi, v.bv_len);
bvec_iter_advance_single(i->bvec, &bi, bv.bv_len);