O_NOTIFICATION_PIPE
if (flags & O_NOTIFICATION_PIPE) {
if (flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT | O_NOTIFICATION_PIPE))
if (p->flags & ~(O_CLOEXEC | O_NONBLOCK | O_DIRECT | O_NOTIFICATION_PIPE))
if (pipe2(pipefd, O_NOTIFICATION_PIPE) == -1) {