block: move set_task_ioprio to blk-ioc.c
[linux-2.6-block.git] / block / ioprio.c
CommitLineData
3dcf60bc 1// SPDX-License-Identifier: GPL-2.0
22e2c507
JA
2/*
3 * fs/ioprio.c
4 *
0fe23479 5 * Copyright (C) 2004 Jens Axboe <axboe@kernel.dk>
22e2c507
JA
6 *
7 * Helper functions for setting/querying io priorities of processes. The
8 * system calls closely mimmick getpriority/setpriority, see the man page for
9 * those. The prio argument is a composite of prio class and prio data, where
10 * the data argument has meaning within that class. The standard scheduling
11 * classes have 8 distinct prio levels, with 0 being the highest prio and 7
12 * being the lowest.
13 *
14 * IOW, setting BE scheduling class with prio 2 is done ala:
15 *
16 * unsigned int prio = (IOPRIO_CLASS_BE << IOPRIO_CLASS_SHIFT) | 2;
17 *
18 * ioprio_set(PRIO_PROCESS, pid, prio);
19 *
898bd37a 20 * See also Documentation/block/ioprio.rst
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JA
21 *
22 */
5a0e3ad6 23#include <linux/gfp.h>
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24#include <linux/kernel.h>
25#include <linux/ioprio.h>
5b825c3a 26#include <linux/cred.h>
22e2c507 27#include <linux/blkdev.h>
16f7e0fe 28#include <linux/capability.h>
9abdc4cd 29#include <linux/syscalls.h>
03e68060 30#include <linux/security.h>
b488893a 31#include <linux/pid_namespace.h>
22e2c507 32
aa434577 33int ioprio_check_cap(int ioprio)
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JA
34{
35 int class = IOPRIO_PRIO_CLASS(ioprio);
36 int data = IOPRIO_PRIO_DATA(ioprio);
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JA
37
38 switch (class) {
39 case IOPRIO_CLASS_RT:
94c4b4fd
AD
40 /*
41 * Originally this only checked for CAP_SYS_ADMIN,
42 * which was implicitly allowed for pid 0 by security
43 * modules such as SELinux. Make sure we check
44 * CAP_SYS_ADMIN first to avoid a denial/avc for
45 * possibly missing CAP_SYS_NICE permission.
46 */
47 if (!capable(CAP_SYS_ADMIN) && !capable(CAP_SYS_NICE))
22e2c507 48 return -EPERM;
df561f66 49 fallthrough;
e29387eb 50 /* rt has prio field too */
22e2c507 51 case IOPRIO_CLASS_BE:
202bc942 52 if (data >= IOPRIO_NR_LEVELS || data < 0)
22e2c507 53 return -EINVAL;
22e2c507
JA
54 break;
55 case IOPRIO_CLASS_IDLE:
56 break;
8ec680e4
JA
57 case IOPRIO_CLASS_NONE:
58 if (data)
59 return -EINVAL;
60 break;
22e2c507
JA
61 default:
62 return -EINVAL;
63 }
64
aa434577
AM
65 return 0;
66}
67
68SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio)
69{
70 struct task_struct *p, *g;
71 struct user_struct *user;
72 struct pid *pgrp;
73 kuid_t uid;
74 int ret;
75
76 ret = ioprio_check_cap(ioprio);
77 if (ret)
78 return ret;
79
22e2c507 80 ret = -ESRCH;
d69b78ba 81 rcu_read_lock();
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JA
82 switch (which) {
83 case IOPRIO_WHO_PROCESS:
84 if (!who)
85 p = current;
86 else
228ebcbe 87 p = find_task_by_vpid(who);
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JA
88 if (p)
89 ret = set_task_ioprio(p, ioprio);
90 break;
91 case IOPRIO_WHO_PGRP:
92 if (!who)
41487c65
EB
93 pgrp = task_pgrp(current);
94 else
b488893a 95 pgrp = find_vpid(who);
40c7fd3f
PZ
96
97 read_lock(&tasklist_lock);
2d70b68d 98 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
22e2c507 99 ret = set_task_ioprio(p, ioprio);
40c7fd3f
PZ
100 if (ret) {
101 read_unlock(&tasklist_lock);
102 goto out;
103 }
2d70b68d 104 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
40c7fd3f
PZ
105 read_unlock(&tasklist_lock);
106
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JA
107 break;
108 case IOPRIO_WHO_USER:
7b44ab97
EB
109 uid = make_kuid(current_user_ns(), who);
110 if (!uid_valid(uid))
111 break;
22e2c507 112 if (!who)
86a264ab 113 user = current_user();
22e2c507 114 else
7b44ab97 115 user = find_user(uid);
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JA
116
117 if (!user)
118 break;
119
612dafab 120 for_each_process_thread(g, p) {
8639b461
BS
121 if (!uid_eq(task_uid(p), uid) ||
122 !task_pid_vnr(p))
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JA
123 continue;
124 ret = set_task_ioprio(p, ioprio);
125 if (ret)
78bd4d48 126 goto free_uid;
612dafab 127 }
78bd4d48 128free_uid:
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129 if (who)
130 free_uid(user);
131 break;
132 default:
133 ret = -EINVAL;
134 }
135
40c7fd3f 136out:
d69b78ba 137 rcu_read_unlock();
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138 return ret;
139}
140
a1836a42
DQ
141static int get_task_ioprio(struct task_struct *p)
142{
143 int ret;
144
145 ret = security_task_getioprio(p);
146 if (ret)
147 goto out;
e70344c0 148 ret = IOPRIO_DEFAULT;
8ba86821 149 task_lock(p);
fd0928df
JA
150 if (p->io_context)
151 ret = p->io_context->ioprio;
8ba86821 152 task_unlock(p);
a1836a42
DQ
153out:
154 return ret;
155}
156
e014ff8d
ON
157int ioprio_best(unsigned short aprio, unsigned short bprio)
158{
ece9c72a 159 if (!ioprio_valid(aprio))
e70344c0 160 aprio = IOPRIO_DEFAULT;
ece9c72a 161 if (!ioprio_valid(bprio))
e70344c0 162 bprio = IOPRIO_DEFAULT;
e014ff8d 163
9a87182c 164 return min(aprio, bprio);
e014ff8d
ON
165}
166
938bb9f5 167SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
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JA
168{
169 struct task_struct *g, *p;
170 struct user_struct *user;
41487c65 171 struct pid *pgrp;
7b44ab97 172 kuid_t uid;
22e2c507 173 int ret = -ESRCH;
a1836a42 174 int tmpio;
22e2c507 175
d69b78ba 176 rcu_read_lock();
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JA
177 switch (which) {
178 case IOPRIO_WHO_PROCESS:
179 if (!who)
180 p = current;
181 else
228ebcbe 182 p = find_task_by_vpid(who);
22e2c507 183 if (p)
a1836a42 184 ret = get_task_ioprio(p);
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JA
185 break;
186 case IOPRIO_WHO_PGRP:
187 if (!who)
41487c65
EB
188 pgrp = task_pgrp(current);
189 else
b488893a 190 pgrp = find_vpid(who);
2d70b68d 191 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
a1836a42
DQ
192 tmpio = get_task_ioprio(p);
193 if (tmpio < 0)
194 continue;
22e2c507 195 if (ret == -ESRCH)
a1836a42 196 ret = tmpio;
22e2c507 197 else
a1836a42 198 ret = ioprio_best(ret, tmpio);
2d70b68d 199 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
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JA
200 break;
201 case IOPRIO_WHO_USER:
7b44ab97 202 uid = make_kuid(current_user_ns(), who);
22e2c507 203 if (!who)
86a264ab 204 user = current_user();
22e2c507 205 else
7b44ab97 206 user = find_user(uid);
22e2c507
JA
207
208 if (!user)
209 break;
210
612dafab 211 for_each_process_thread(g, p) {
8639b461
BS
212 if (!uid_eq(task_uid(p), user->uid) ||
213 !task_pid_vnr(p))
22e2c507 214 continue;
a1836a42
DQ
215 tmpio = get_task_ioprio(p);
216 if (tmpio < 0)
217 continue;
22e2c507 218 if (ret == -ESRCH)
a1836a42 219 ret = tmpio;
22e2c507 220 else
a1836a42 221 ret = ioprio_best(ret, tmpio);
612dafab 222 }
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JA
223
224 if (who)
225 free_uid(user);
226 break;
227 default:
228 ret = -EINVAL;
229 }
230
d69b78ba 231 rcu_read_unlock();
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JA
232 return ret;
233}