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 */
19 static 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 */
30 static inline int task_nice_ioprio(struct task_struct *task)
31 {
32 return (task_nice(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 */
39 static inline int task_nice_ioclass(struct task_struct *task)
40 {
41 if (task->policy == SCHED_IDLE)
42 return IOPRIO_CLASS_IDLE;
43 else if (task_is_realtime(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 */
57 static 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_DEFAULT;
64
65 if (p != current)
66 lockdep_assert_held(&p->alloc_lock);
67
68 prio = ioc->ioprio;
69 if (IOPRIO_PRIO_CLASS(prio) == IOPRIO_CLASS_NONE)
70 prio = IOPRIO_PRIO_VALUE(task_nice_ioclass(p),
71 task_nice_ioprio(p));
72 return prio;
73 }
74 #else
75 static inline int __get_task_ioprio(struct task_struct *p)
76 {
77 return IOPRIO_DEFAULT;
78 }
79 #endif /* CONFIG_BLOCK */
80
81 static inline int get_current_ioprio(void)
82 {
83 return __get_task_ioprio(current);
84 }
85
86 extern int set_task_ioprio(struct task_struct *task, int ioprio);
87
88 #ifdef CONFIG_BLOCK
89 extern int ioprio_check_cap(int ioprio);
90 #else
91 static inline int ioprio_check_cap(int ioprio)
92 {
93 return -ENOTBLK;
94 }
95 #endif /* CONFIG_BLOCK */
96
97 #endif
98
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