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 */
27 enum {
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
39 enum {
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 */
task_nice_ioprio(struct task_struct * task)54 static 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 */
task_nice_ioclass(struct task_struct * task)63 static 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 * If the calling process has set an I/O priority, use that. Otherwise, return
75 * the default I/O priority.
76 */
get_current_ioprio(void)77 static inline int get_current_ioprio(void)
78 {
79 struct io_context *ioc = current->io_context;
80
81 if (ioc)
82 return ioc->ioprio;
83 return IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, 0);
84 }
85
86 /*
87 * For inheritance, return the highest of the two given priorities
88 */
89 extern int ioprio_best(unsigned short aprio, unsigned short bprio);
90
91 extern int set_task_ioprio(struct task_struct *task, int ioprio);
92
93 #ifdef CONFIG_BLOCK
94 extern int ioprio_check_cap(int ioprio);
95 #else
ioprio_check_cap(int ioprio)96 static inline int ioprio_check_cap(int ioprio)
97 {
98 return -ENOTBLK;
99 }
100 #endif /* CONFIG_BLOCK */
101
102 #endif
103
