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22e2c507
JA
1/*
2 * fs/ioprio.c
3 *
0fe23479 4 * Copyright (C) 2004 Jens Axboe <axboe@kernel.dk>
22e2c507
JA
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 */
5a0e3ad6 22#include <linux/gfp.h>
22e2c507 23#include <linux/kernel.h>
afeacc8c 24#include <linux/export.h>
22e2c507
JA
25#include <linux/ioprio.h>
26#include <linux/blkdev.h>
16f7e0fe 27#include <linux/capability.h>
9abdc4cd 28#include <linux/syscalls.h>
03e68060 29#include <linux/security.h>
b488893a 30#include <linux/pid_namespace.h>
22e2c507 31
b3881f74 32int set_task_ioprio(struct task_struct *task, int ioprio)
22e2c507 33{
03e68060 34 int err;
22e2c507 35 struct io_context *ioc;
c69e8d9c 36 const struct cred *cred = current_cred(), *tcred;
22e2c507 37
c69e8d9c
DH
38 rcu_read_lock();
39 tcred = __task_cred(task);
8e96e3b7
EB
40 if (!uid_eq(tcred->uid, cred->euid) &&
41 !uid_eq(tcred->uid, cred->uid) && !capable(CAP_SYS_NICE)) {
c69e8d9c 42 rcu_read_unlock();
22e2c507 43 return -EPERM;
c69e8d9c
DH
44 }
45 rcu_read_unlock();
22e2c507 46
03e68060
JM
47 err = security_task_setioprio(task, ioprio);
48 if (err)
49 return err;
50
6e736be7
TH
51 ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE);
52 if (ioc) {
2b566fa5 53 ioc->ioprio = ioprio;
11a3122f 54 put_io_context(ioc);
fd0928df 55 }
22e2c507 56
fd0928df 57 return err;
22e2c507 58}
b3881f74 59EXPORT_SYMBOL_GPL(set_task_ioprio);
22e2c507 60
938bb9f5 61SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio)
22e2c507
JA
62{
63 int class = IOPRIO_PRIO_CLASS(ioprio);
64 int data = IOPRIO_PRIO_DATA(ioprio);
65 struct task_struct *p, *g;
66 struct user_struct *user;
41487c65 67 struct pid *pgrp;
7b44ab97 68 kuid_t uid;
22e2c507
JA
69 int ret;
70
71 switch (class) {
72 case IOPRIO_CLASS_RT:
73 if (!capable(CAP_SYS_ADMIN))
74 return -EPERM;
75 /* fall through, rt has prio field too */
76 case IOPRIO_CLASS_BE:
77 if (data >= IOPRIO_BE_NR || data < 0)
78 return -EINVAL;
79
80 break;
81 case IOPRIO_CLASS_IDLE:
82 break;
8ec680e4
JA
83 case IOPRIO_CLASS_NONE:
84 if (data)
85 return -EINVAL;
86 break;
22e2c507
JA
87 default:
88 return -EINVAL;
89 }
90
91 ret = -ESRCH;
d69b78ba 92 rcu_read_lock();
22e2c507
JA
93 switch (which) {
94 case IOPRIO_WHO_PROCESS:
95 if (!who)
96 p = current;
97 else
228ebcbe 98 p = find_task_by_vpid(who);
22e2c507
JA
99 if (p)
100 ret = set_task_ioprio(p, ioprio);
101 break;
102 case IOPRIO_WHO_PGRP:
103 if (!who)
41487c65
EB
104 pgrp = task_pgrp(current);
105 else
b488893a 106 pgrp = find_vpid(who);
2d70b68d 107 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
22e2c507
JA
108 ret = set_task_ioprio(p, ioprio);
109 if (ret)
110 break;
2d70b68d 111 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
22e2c507
JA
112 break;
113 case IOPRIO_WHO_USER:
7b44ab97
EB
114 uid = make_kuid(current_user_ns(), who);
115 if (!uid_valid(uid))
116 break;
22e2c507 117 if (!who)
86a264ab 118 user = current_user();
22e2c507 119 else
7b44ab97 120 user = find_user(uid);
22e2c507
JA
121
122 if (!user)
123 break;
124
125 do_each_thread(g, p) {
078de5f7 126 if (!uid_eq(task_uid(p), uid))
22e2c507
JA
127 continue;
128 ret = set_task_ioprio(p, ioprio);
129 if (ret)
78bd4d48 130 goto free_uid;
22e2c507 131 } while_each_thread(g, p);
78bd4d48 132free_uid:
22e2c507
JA
133 if (who)
134 free_uid(user);
135 break;
136 default:
137 ret = -EINVAL;
138 }
139
d69b78ba 140 rcu_read_unlock();
22e2c507
JA
141 return ret;
142}
143
a1836a42
DQ
144static int get_task_ioprio(struct task_struct *p)
145{
146 int ret;
147
148 ret = security_task_getioprio(p);
149 if (ret)
150 goto out;
fd0928df
JA
151 ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM);
152 if (p->io_context)
153 ret = p->io_context->ioprio;
a1836a42
DQ
154out:
155 return ret;
156}
157
e014ff8d
ON
158int ioprio_best(unsigned short aprio, unsigned short bprio)
159{
160 unsigned short aclass = IOPRIO_PRIO_CLASS(aprio);
161 unsigned short bclass = IOPRIO_PRIO_CLASS(bprio);
162
e014ff8d
ON
163 if (aclass == IOPRIO_CLASS_NONE)
164 aclass = IOPRIO_CLASS_BE;
165 if (bclass == IOPRIO_CLASS_NONE)
166 bclass = IOPRIO_CLASS_BE;
167
168 if (aclass == bclass)
169 return min(aprio, bprio);
170 if (aclass > bclass)
171 return bprio;
172 else
173 return aprio;
174}
175
938bb9f5 176SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
22e2c507
JA
177{
178 struct task_struct *g, *p;
179 struct user_struct *user;
41487c65 180 struct pid *pgrp;
7b44ab97 181 kuid_t uid;
22e2c507 182 int ret = -ESRCH;
a1836a42 183 int tmpio;
22e2c507 184
d69b78ba 185 rcu_read_lock();
22e2c507
JA
186 switch (which) {
187 case IOPRIO_WHO_PROCESS:
188 if (!who)
189 p = current;
190 else
228ebcbe 191 p = find_task_by_vpid(who);
22e2c507 192 if (p)
a1836a42 193 ret = get_task_ioprio(p);
22e2c507
JA
194 break;
195 case IOPRIO_WHO_PGRP:
196 if (!who)
41487c65
EB
197 pgrp = task_pgrp(current);
198 else
b488893a 199 pgrp = find_vpid(who);
2d70b68d 200 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
a1836a42
DQ
201 tmpio = get_task_ioprio(p);
202 if (tmpio < 0)
203 continue;
22e2c507 204 if (ret == -ESRCH)
a1836a42 205 ret = tmpio;
22e2c507 206 else
a1836a42 207 ret = ioprio_best(ret, tmpio);
2d70b68d 208 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
22e2c507
JA
209 break;
210 case IOPRIO_WHO_USER:
7b44ab97 211 uid = make_kuid(current_user_ns(), who);
22e2c507 212 if (!who)
86a264ab 213 user = current_user();
22e2c507 214 else
7b44ab97 215 user = find_user(uid);
22e2c507
JA
216
217 if (!user)
218 break;
219
220 do_each_thread(g, p) {
078de5f7 221 if (!uid_eq(task_uid(p), user->uid))
22e2c507 222 continue;
a1836a42
DQ
223 tmpio = get_task_ioprio(p);
224 if (tmpio < 0)
225 continue;
22e2c507 226 if (ret == -ESRCH)
a1836a42 227 ret = tmpio;
22e2c507 228 else
a1836a42 229 ret = ioprio_best(ret, tmpio);
22e2c507
JA
230 } while_each_thread(g, p);
231
232 if (who)
233 free_uid(user);
234 break;
235 default:
236 ret = -EINVAL;
237 }
238
d69b78ba 239 rcu_read_unlock();
22e2c507
JA
240 return ret;
241}