1#ifndef IOPRIO_H
2#define IOPRIO_H
3
4#include <linux/sched.h>
5
6/*
7 * Gives us 8 prio classes with 13-bits of data for each class
8 */
9#define IOPRIO_BITS		(16)
10#define IOPRIO_CLASS_SHIFT	(13)
11#define IOPRIO_PRIO_MASK	((1UL << IOPRIO_CLASS_SHIFT) - 1)
12
13#define IOPRIO_PRIO_CLASS(mask)	((mask) >> IOPRIO_CLASS_SHIFT)
14#define IOPRIO_PRIO_DATA(mask)	((mask) & IOPRIO_PRIO_MASK)
15#define IOPRIO_PRIO_VALUE(class, data)	(((class) << IOPRIO_CLASS_SHIFT) | data)
16
17#define ioprio_valid(mask)	(IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)
18
19/*
20 * These are the io priority groups as implemented by CFQ. RT is the realtime
21 * class, it always gets premium service. BE is the best-effort scheduling
22 * class, the default for any process. IDLE is the idle scheduling class, it
23 * is only served when no one else is using the disk.
24 */
25enum {
26	IOPRIO_CLASS_NONE,
27	IOPRIO_CLASS_RT,
28	IOPRIO_CLASS_BE,
29	IOPRIO_CLASS_IDLE,
30};
31
32/*
33 * 8 best effort priority levels are supported
34 */
35#define IOPRIO_BE_NR	(8)
36
37enum {
38	IOPRIO_WHO_PROCESS = 1,
39	IOPRIO_WHO_PGRP,
40	IOPRIO_WHO_USER,
41};
42
43/*
44 * if process has set io priority explicitly, use that. if not, convert
45 * the cpu scheduler nice value to an io priority
46 */
47#define IOPRIO_NORM	(4)
48static inline int task_ioprio(struct task_struct *task)
49{
50	WARN_ON(!ioprio_valid(task->ioprio));
51	return IOPRIO_PRIO_DATA(task->ioprio);
52}
53
54static inline int task_nice_ioprio(struct task_struct *task)
55{
56	return (task_nice(task) + 20) / 5;
57}
58
59/*
60 * For inheritance, return the highest of the two given priorities
61 */
62extern int ioprio_best(unsigned short aprio, unsigned short bprio);
63
64#endif
65