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CommitLineData
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) {
8639b461
BS
126 if (!uid_eq(task_uid(p), uid) ||
127 !task_pid_vnr(p))
22e2c507
JA
128 continue;
129 ret = set_task_ioprio(p, ioprio);
130 if (ret)
78bd4d48 131 goto free_uid;
22e2c507 132 } while_each_thread(g, p);
78bd4d48 133free_uid:
22e2c507
JA
134 if (who)
135 free_uid(user);
136 break;
137 default:
138 ret = -EINVAL;
139 }
140
d69b78ba 141 rcu_read_unlock();
22e2c507
JA
142 return ret;
143}
144
a1836a42
DQ
145static int get_task_ioprio(struct task_struct *p)
146{
147 int ret;
148
149 ret = security_task_getioprio(p);
150 if (ret)
151 goto out;
fd0928df 152 ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM);
8ba86821 153 task_lock(p);
fd0928df
JA
154 if (p->io_context)
155 ret = p->io_context->ioprio;
8ba86821 156 task_unlock(p);
a1836a42
DQ
157out:
158 return ret;
159}
160
e014ff8d
ON
161int ioprio_best(unsigned short aprio, unsigned short bprio)
162{
ece9c72a
JK
163 unsigned short aclass;
164 unsigned short bclass;
e014ff8d 165
ece9c72a
JK
166 if (!ioprio_valid(aprio))
167 aprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
168 if (!ioprio_valid(bprio))
169 bprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
e014ff8d 170
ece9c72a
JK
171 aclass = IOPRIO_PRIO_CLASS(aprio);
172 bclass = IOPRIO_PRIO_CLASS(bprio);
e014ff8d
ON
173 if (aclass == bclass)
174 return min(aprio, bprio);
175 if (aclass > bclass)
176 return bprio;
177 else
178 return aprio;
179}
180
938bb9f5 181SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
22e2c507
JA
182{
183 struct task_struct *g, *p;
184 struct user_struct *user;
41487c65 185 struct pid *pgrp;
7b44ab97 186 kuid_t uid;
22e2c507 187 int ret = -ESRCH;
a1836a42 188 int tmpio;
22e2c507 189
d69b78ba 190 rcu_read_lock();
22e2c507
JA
191 switch (which) {
192 case IOPRIO_WHO_PROCESS:
193 if (!who)
194 p = current;
195 else
228ebcbe 196 p = find_task_by_vpid(who);
22e2c507 197 if (p)
a1836a42 198 ret = get_task_ioprio(p);
22e2c507
JA
199 break;
200 case IOPRIO_WHO_PGRP:
201 if (!who)
41487c65
EB
202 pgrp = task_pgrp(current);
203 else
b488893a 204 pgrp = find_vpid(who);
2d70b68d 205 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
a1836a42
DQ
206 tmpio = get_task_ioprio(p);
207 if (tmpio < 0)
208 continue;
22e2c507 209 if (ret == -ESRCH)
a1836a42 210 ret = tmpio;
22e2c507 211 else
a1836a42 212 ret = ioprio_best(ret, tmpio);
2d70b68d 213 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
22e2c507
JA
214 break;
215 case IOPRIO_WHO_USER:
7b44ab97 216 uid = make_kuid(current_user_ns(), who);
22e2c507 217 if (!who)
86a264ab 218 user = current_user();
22e2c507 219 else
7b44ab97 220 user = find_user(uid);
22e2c507
JA
221
222 if (!user)
223 break;
224
225 do_each_thread(g, p) {
8639b461
BS
226 if (!uid_eq(task_uid(p), user->uid) ||
227 !task_pid_vnr(p))
22e2c507 228 continue;
a1836a42
DQ
229 tmpio = get_task_ioprio(p);
230 if (tmpio < 0)
231 continue;
22e2c507 232 if (ret == -ESRCH)
a1836a42 233 ret = tmpio;
22e2c507 234 else
a1836a42 235 ret = ioprio_best(ret, tmpio);
22e2c507
JA
236 } while_each_thread(g, p);
237
238 if (who)
239 free_uid(user);
240 break;
241 default:
242 ret = -EINVAL;
243 }
244
d69b78ba 245 rcu_read_unlock();
22e2c507
JA
246 return ret;
247}