sg_set_folio
sg_set_folio(sg, folio, nr_pages * PAGE_SIZE, 0);
sg_set_folio(&sg[i], folios[i], this_len, folio_descs[i].offset);
sg_set_folio(&req->chain.ssg, folio, len, off);
sg_set_folio(&req->chain.dsg, folio, len, off);
sg_set_folio(&output, folio, PAGE_SIZE, 0);