include/uapi/linux/ioprio.h

#ifndef _UAPI__IOPRIO_H
#define _UAPI__IOPRIO_H

/*
 * Gives us 8 prio classes with 13-bits of data for each class
 */
#define IOPRIO_BITS		(16)
#define IOPRIO_CLASS_SHIFT	(13)

/*
 * These are the io priority groups as implemented by CFQ. RT is the realtime
 * class, it always gets premium service. BE is the best-effort scheduling
 * class, the default for any process. IDLE is the idle scheduling class, it
 * is only served when no one else is using the disk.
 */
enum {
	IOPRIO_CLASS_NONE,
	IOPRIO_CLASS_RT,
	IOPRIO_CLASS_BE,
	IOPRIO_CLASS_IDLE,
};

/*
 * 8 best effort priority levels are supported
 */
#define IOPRIO_BE_NR	(8)

enum {
	IOPRIO_WHO_PROCESS = 1,
	IOPRIO_WHO_PGRP,
	IOPRIO_WHO_USER,
};

#endif