L9P_ACE_READ_DATA
op = L9P_ACE_READ_DATA;
op = L9P_ACE_READ_DATA | L9P_ACE_WRITE_DATA;
error = check_access(L9P_ACE_READ_DATA, NULL, NULL,
(L9P_ACE_READ_DATA | L9P_ACE_READ_NAMED_ATTRS |
mask |= L9P_ACE_READ_DATA;