l9p_pufcall
if (l9p_pufcall(&req->lr_req_msg, &req->lr_req, conn->lc_version) != 0) {
int l9p_pufcall(struct l9p_message *msg, union l9p_fcall *fcall,
l9p_pufcall(&req->lr_resp_msg, &req->lr_resp, conn->lc_version);