1/* SPDX-License-Identifier: GPL-2.0 */
2#ifndef IOPRIO_H
3#define IOPRIO_H
4
5#include <linux/sched.h>
6#include <linux/sched/rt.h>
7#include <linux/iocontext.h>
8
9/*
10 * Gives us 8 prio classes with 13-bits of data for each class
11 */
12#define IOPRIO_CLASS_SHIFT (13)
13#define IOPRIO_PRIO_MASK ((1UL << IOPRIO_CLASS_SHIFT) - 1)
14
15#define IOPRIO_PRIO_CLASS(mask) ((mask) >> IOPRIO_CLASS_SHIFT)
16#define IOPRIO_PRIO_DATA(mask) ((mask) & IOPRIO_PRIO_MASK)
17#define IOPRIO_PRIO_VALUE(class, data) (((class) << IOPRIO_CLASS_SHIFT) | data)
18
19#define ioprio_valid(mask) (IOPRIO_PRIO_CLASS((mask)) != IOPRIO_CLASS_NONE)
20
21/*
22 * These are the io priority groups as implemented by CFQ. RT is the realtime
23 * class, it always gets premium service. BE is the best-effort scheduling
24 * class, the default for any process. IDLE is the idle scheduling class, it
25 * is only served when no one else is using the disk.
26 */
27enum {
28 IOPRIO_CLASS_NONE,
29 IOPRIO_CLASS_RT,
30 IOPRIO_CLASS_BE,
31 IOPRIO_CLASS_IDLE,
32};
33
34/*
35 * 8 best effort priority levels are supported
36 */
37#define IOPRIO_BE_NR (8)
38
39enum {
40 IOPRIO_WHO_PROCESS = 1,
41 IOPRIO_WHO_PGRP,
42 IOPRIO_WHO_USER,
43};
44
45/*
46 * Fallback BE priority
47 */
48#define IOPRIO_NORM (4)
49
50/*
51 * if process has set io priority explicitly, use that. if not, convert
52 * the cpu scheduler nice value to an io priority
53 */
54static inline int task_nice_ioprio(struct task_struct *task)
55{
56 return (task_nice(task) + 20) / 5;
57}
58
59/*
60 * This is for the case where the task hasn't asked for a specific IO class.
61 * Check for idle and rt task process, and return appropriate IO class.
62 */
63static inline int task_nice_ioclass(struct task_struct *task)
64{
65 if (task->policy == SCHED_IDLE)
66 return IOPRIO_CLASS_IDLE;
67 else if (task_is_realtime(task))
68 return IOPRIO_CLASS_RT;
69 else
70 return IOPRIO_CLASS_BE;
71}
72
73/*
74 * For inheritance, return the highest of the two given priorities
75 */
76extern int ioprio_best(unsigned short aprio, unsigned short bprio);
77
78extern int set_task_ioprio(struct task_struct *task, int ioprio);
79
80#ifdef CONFIG_BLOCK
81extern int ioprio_check_cap(int ioprio);
82#else
83static inline int ioprio_check_cap(int ioprio)
84{
85 return -ENOTBLK;
86}
87#endif /* CONFIG_BLOCK */
88
89#endif
90