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#include <uapi/linux/ioprio.h>
10
11/*
12 * Default IO priority.
13 */
14#define IOPRIO_DEFAULT IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0)
15
16/*
17 * Check that a priority value has a valid class.
18 */
19static inline bool ioprio_valid(unsigned short ioprio)
20{
21 unsigned short class = IOPRIO_PRIO_CLASS(ioprio);
22
23 return class > IOPRIO_CLASS_NONE && class <= IOPRIO_CLASS_IDLE;
24}
25
26/*
27 * if process has set io priority explicitly, use that. if not, convert
28 * the cpu scheduler nice value to an io priority
29 */
30static inline int task_nice_ioprio(struct task_struct *task)
31{
32 return (task_nice(p: task) + 20) / 5;
33}
34
35/*
36 * This is for the case where the task hasn't asked for a specific IO class.
37 * Check for idle and rt task process, and return appropriate IO class.
38 */
39static inline int task_nice_ioclass(struct task_struct *task)
40{
41 if (task->policy == SCHED_IDLE)
42 return IOPRIO_CLASS_IDLE;
43 else if (rt_or_dl_task_policy(tsk: task))
44 return IOPRIO_CLASS_RT;
45 else
46 return IOPRIO_CLASS_BE;
47}
48
49#ifdef CONFIG_BLOCK
50/*
51 * If the task has set an I/O priority, use that. Otherwise, return
52 * the default I/O priority.
53 *
54 * Expected to be called for current task or with task_lock() held to keep
55 * io_context stable.
56 */
57static inline int __get_task_ioprio(struct task_struct *p)
58{
59 struct io_context *ioc = p->io_context;
60 int prio;
61
62 if (!ioc)
63 return IOPRIO_PRIO_VALUE(task_nice_ioclass(p),
64 task_nice_ioprio(p));
65
66 if (p != current)
67 lockdep_assert_held(&p->alloc_lock);
68
69 prio = ioc->ioprio;
70 if (IOPRIO_PRIO_CLASS(prio) == IOPRIO_CLASS_NONE)
71 prio = IOPRIO_PRIO_VALUE(task_nice_ioclass(p),
72 task_nice_ioprio(p));
73 return prio;
74}
75#else
76static inline int __get_task_ioprio(struct task_struct *p)
77{
78 return IOPRIO_DEFAULT;
79}
80#endif /* CONFIG_BLOCK */
81
82static inline int get_current_ioprio(void)
83{
84 return __get_task_ioprio(current);
85}
86
87extern int set_task_ioprio(struct task_struct *task, int ioprio);
88
89#ifdef CONFIG_BLOCK
90extern int ioprio_check_cap(int ioprio);
91#else
92static inline int ioprio_check_cap(int ioprio)
93{
94 return -ENOTBLK;
95}
96#endif /* CONFIG_BLOCK */
97
98#endif
99