Lo_unbound
if (lo->lo_state != Lo_unbound)
WRITE_ONCE(lo->lo_state, Lo_unbound);
WRITE_ONCE(lo->lo_state, Lo_unbound);
if (lo->lo_state != Lo_unbound || disk_openers(lo->lo_disk) > 0) {
data_race(READ_ONCE(lo->lo_state)) == Lo_unbound)