blob: ca77008146c02494018bf84c28b370f0e0a6b39a [file] [log] [blame]
Jens Axboe22e2c502005-06-27 10:55:12 +02001/*
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>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080025#include <linux/capability.h>
Adrian Bunk9abdc4c2005-11-08 16:57:02 +010026#include <linux/syscalls.h>
Jens Axboe22e2c502005-06-27 10:55:12 +020027
28static int set_task_ioprio(struct task_struct *task, int ioprio)
29{
30 struct io_context *ioc;
31
32 if (task->uid != current->euid &&
33 task->uid != current->uid && !capable(CAP_SYS_NICE))
34 return -EPERM;
35
36 task_lock(task);
37
38 task->ioprio = ioprio;
39
40 ioc = task->io_context;
41 if (ioc && ioc->set_ioprio)
42 ioc->set_ioprio(ioc, ioprio);
43
44 task_unlock(task);
45 return 0;
46}
47
Anton Blanchardcf366802005-07-07 17:56:13 -070048asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
Jens Axboe22e2c502005-06-27 10:55:12 +020049{
50 int class = IOPRIO_PRIO_CLASS(ioprio);
51 int data = IOPRIO_PRIO_DATA(ioprio);
52 struct task_struct *p, *g;
53 struct user_struct *user;
54 int ret;
55
56 switch (class) {
57 case IOPRIO_CLASS_RT:
58 if (!capable(CAP_SYS_ADMIN))
59 return -EPERM;
60 /* fall through, rt has prio field too */
61 case IOPRIO_CLASS_BE:
62 if (data >= IOPRIO_BE_NR || data < 0)
63 return -EINVAL;
64
65 break;
66 case IOPRIO_CLASS_IDLE:
Linus Torvaldsf6fdd7d2005-08-20 18:51:29 -070067 if (!capable(CAP_SYS_ADMIN))
68 return -EPERM;
Jens Axboe22e2c502005-06-27 10:55:12 +020069 break;
70 default:
71 return -EINVAL;
72 }
73
74 ret = -ESRCH;
75 read_lock_irq(&tasklist_lock);
76 switch (which) {
77 case IOPRIO_WHO_PROCESS:
78 if (!who)
79 p = current;
80 else
81 p = find_task_by_pid(who);
82 if (p)
83 ret = set_task_ioprio(p, ioprio);
84 break;
85 case IOPRIO_WHO_PGRP:
86 if (!who)
87 who = process_group(current);
88 do_each_task_pid(who, PIDTYPE_PGID, p) {
89 ret = set_task_ioprio(p, ioprio);
90 if (ret)
91 break;
92 } while_each_task_pid(who, PIDTYPE_PGID, p);
93 break;
94 case IOPRIO_WHO_USER:
95 if (!who)
96 user = current->user;
97 else
98 user = find_user(who);
99
100 if (!user)
101 break;
102
103 do_each_thread(g, p) {
104 if (p->uid != who)
105 continue;
106 ret = set_task_ioprio(p, ioprio);
107 if (ret)
108 break;
109 } while_each_thread(g, p);
110
111 if (who)
112 free_uid(user);
113 break;
114 default:
115 ret = -EINVAL;
116 }
117
118 read_unlock_irq(&tasklist_lock);
119 return ret;
120}
121
Anton Blanchardcf366802005-07-07 17:56:13 -0700122asmlinkage long sys_ioprio_get(int which, int who)
Jens Axboe22e2c502005-06-27 10:55:12 +0200123{
124 struct task_struct *g, *p;
125 struct user_struct *user;
126 int ret = -ESRCH;
127
128 read_lock_irq(&tasklist_lock);
129 switch (which) {
130 case IOPRIO_WHO_PROCESS:
131 if (!who)
132 p = current;
133 else
134 p = find_task_by_pid(who);
135 if (p)
136 ret = p->ioprio;
137 break;
138 case IOPRIO_WHO_PGRP:
139 if (!who)
140 who = process_group(current);
141 do_each_task_pid(who, PIDTYPE_PGID, p) {
142 if (ret == -ESRCH)
143 ret = p->ioprio;
144 else
145 ret = ioprio_best(ret, p->ioprio);
146 } while_each_task_pid(who, PIDTYPE_PGID, p);
147 break;
148 case IOPRIO_WHO_USER:
149 if (!who)
150 user = current->user;
151 else
152 user = find_user(who);
153
154 if (!user)
155 break;
156
157 do_each_thread(g, p) {
158 if (p->uid != user->uid)
159 continue;
160 if (ret == -ESRCH)
161 ret = p->ioprio;
162 else
163 ret = ioprio_best(ret, p->ioprio);
164 } while_each_thread(g, p);
165
166 if (who)
167 free_uid(user);
168 break;
169 default:
170 ret = -EINVAL;
171 }
172
173 read_unlock_irq(&tasklist_lock);
174 return ret;
175}
176