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  */
ioprio_valid(unsigned short ioprio)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  */
task_nice_ioprio(struct task_struct * task)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  */
task_nice_ioclass(struct task_struct * task)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 (rt_or_dl_task_policy(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  */
__get_task_ioprio(struct task_struct * p)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
__get_task_ioprio(struct task_struct * p)75 static inline int __get_task_ioprio(struct task_struct *p)
76 {
77 	return IOPRIO_DEFAULT;
78 }
79 #endif /* CONFIG_BLOCK */
80 
get_current_ioprio(void)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
ioprio_check_cap(int ioprio)91 static inline int ioprio_check_cap(int ioprio)
92 {
93 	return -ENOTBLK;
94 }
95 #endif /* CONFIG_BLOCK */
96 
97 #endif
98