receive_extralen
int len = receive_extralen(ms);
error = send_message(mh, ms, ms_in->m_extra, receive_extralen(ms_in));
len = receive_extralen(ms);
namelen = receive_extralen(ms);
len = receive_extralen(ms);
len = receive_extralen(ms);
static int receive_extralen(const struct dlm_message *ms);