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Linux kernel mirror (for testing)
git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
kernel
os
linux
1/*
2 * fs/ioprio.c
3 *
4 * Copyright (C) 2004 Jens Axboe <axboe@suse.de>
5 *
6 * Helper functions for setting/querying io priorities of processes. The
7 * system calls closely mimmick getpriority/setpriority, see the man page for
8 * those. The prio argument is a composite of prio class and prio data, where
9 * the data argument has meaning within that class. The standard scheduling
10 * classes have 8 distinct prio levels, with 0 being the highest prio and 7
11 * being the lowest.
12 *
13 * IOW, setting BE scheduling class with prio 2 is done ala:
14 *
15 * unsigned int prio = (IOPRIO_CLASS_BE << IOPRIO_CLASS_SHIFT) | 2;
16 *
17 * ioprio_set(PRIO_PROCESS, pid, prio);
18 *
19 * See also Documentation/block/ioprio.txt
20 *
21 */
22#include <linux/kernel.h>
23#include <linux/ioprio.h>
24#include <linux/blkdev.h>
25
26static int set_task_ioprio(struct task_struct *task, int ioprio)
27{
28 struct io_context *ioc;
29
30 if (task->uid != current->euid &&
31 task->uid != current->uid && !capable(CAP_SYS_NICE))
32 return -EPERM;
33
34 task_lock(task);
35
36 task->ioprio = ioprio;
37
38 ioc = task->io_context;
39 if (ioc && ioc->set_ioprio)
40 ioc->set_ioprio(ioc, ioprio);
41
42 task_unlock(task);
43 return 0;
44}
45
46asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
47{
48 int class = IOPRIO_PRIO_CLASS(ioprio);
49 int data = IOPRIO_PRIO_DATA(ioprio);
50 struct task_struct *p, *g;
51 struct user_struct *user;
52 int ret;
53
54 switch (class) {
55 case IOPRIO_CLASS_RT:
56 if (!capable(CAP_SYS_ADMIN))
57 return -EPERM;
58 /* fall through, rt has prio field too */
59 case IOPRIO_CLASS_BE:
60 if (data >= IOPRIO_BE_NR || data < 0)
61 return -EINVAL;
62
63 break;
64 case IOPRIO_CLASS_IDLE:
65 if (!capable(CAP_SYS_ADMIN))
66 return -EPERM;
67 break;
68 default:
69 return -EINVAL;
70 }
71
72 ret = -ESRCH;
73 read_lock_irq(&tasklist_lock);
74 switch (which) {
75 case IOPRIO_WHO_PROCESS:
76 if (!who)
77 p = current;
78 else
79 p = find_task_by_pid(who);
80 if (p)
81 ret = set_task_ioprio(p, ioprio);
82 break;
83 case IOPRIO_WHO_PGRP:
84 if (!who)
85 who = process_group(current);
86 do_each_task_pid(who, PIDTYPE_PGID, p) {
87 ret = set_task_ioprio(p, ioprio);
88 if (ret)
89 break;
90 } while_each_task_pid(who, PIDTYPE_PGID, p);
91 break;
92 case IOPRIO_WHO_USER:
93 if (!who)
94 user = current->user;
95 else
96 user = find_user(who);
97
98 if (!user)
99 break;
100
101 do_each_thread(g, p) {
102 if (p->uid != who)
103 continue;
104 ret = set_task_ioprio(p, ioprio);
105 if (ret)
106 break;
107 } while_each_thread(g, p);
108
109 if (who)
110 free_uid(user);
111 break;
112 default:
113 ret = -EINVAL;
114 }
115
116 read_unlock_irq(&tasklist_lock);
117 return ret;
118}
119
120asmlinkage long sys_ioprio_get(int which, int who)
121{
122 struct task_struct *g, *p;
123 struct user_struct *user;
124 int ret = -ESRCH;
125
126 read_lock_irq(&tasklist_lock);
127 switch (which) {
128 case IOPRIO_WHO_PROCESS:
129 if (!who)
130 p = current;
131 else
132 p = find_task_by_pid(who);
133 if (p)
134 ret = p->ioprio;
135 break;
136 case IOPRIO_WHO_PGRP:
137 if (!who)
138 who = process_group(current);
139 do_each_task_pid(who, PIDTYPE_PGID, p) {
140 if (ret == -ESRCH)
141 ret = p->ioprio;
142 else
143 ret = ioprio_best(ret, p->ioprio);
144 } while_each_task_pid(who, PIDTYPE_PGID, p);
145 break;
146 case IOPRIO_WHO_USER:
147 if (!who)
148 user = current->user;
149 else
150 user = find_user(who);
151
152 if (!user)
153 break;
154
155 do_each_thread(g, p) {
156 if (p->uid != user->uid)
157 continue;
158 if (ret == -ESRCH)
159 ret = p->ioprio;
160 else
161 ret = ioprio_best(ret, p->ioprio);
162 } while_each_thread(g, p);
163
164 if (who)
165 free_uid(user);
166 break;
167 default:
168 ret = -EINVAL;
169 }
170
171 read_unlock_irq(&tasklist_lock);
172 return ret;
173}
174