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block, cfq: misc updates to cfq_io_context
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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);
40 if (tcred->uid != cred->euid &&
41 tcred->uid != cred->uid && !capable(CAP_SYS_NICE)) {
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) {
fd0928df 53 ioc->ioprio = ioprio;
fc46379d 54 ioc->ioprio_changed = 1;
6e736be7 55 put_io_context(ioc);
fd0928df 56 }
22e2c507 57
fd0928df 58 return err;
22e2c507 59}
b3881f74 60EXPORT_SYMBOL_GPL(set_task_ioprio);
22e2c507 61
938bb9f5 62SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio)
22e2c507
JA
63{
64 int class = IOPRIO_PRIO_CLASS(ioprio);
65 int data = IOPRIO_PRIO_DATA(ioprio);
66 struct task_struct *p, *g;
67 struct user_struct *user;
41487c65 68 struct pid *pgrp;
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);
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JA
112 break;
113 case IOPRIO_WHO_USER:
114 if (!who)
86a264ab 115 user = current_user();
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JA
116 else
117 user = find_user(who);
118
119 if (!user)
120 break;
121
122 do_each_thread(g, p) {
d69b78ba 123 if (__task_cred(p)->uid != who)
22e2c507
JA
124 continue;
125 ret = set_task_ioprio(p, ioprio);
126 if (ret)
78bd4d48 127 goto free_uid;
22e2c507 128 } while_each_thread(g, p);
78bd4d48 129free_uid:
22e2c507
JA
130 if (who)
131 free_uid(user);
132 break;
133 default:
134 ret = -EINVAL;
135 }
136
d69b78ba 137 rcu_read_unlock();
22e2c507
JA
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;
fd0928df
JA
148 ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM);
149 if (p->io_context)
150 ret = p->io_context->ioprio;
a1836a42
DQ
151out:
152 return ret;
153}
154
e014ff8d
ON
155int ioprio_best(unsigned short aprio, unsigned short bprio)
156{
157 unsigned short aclass = IOPRIO_PRIO_CLASS(aprio);
158 unsigned short bclass = IOPRIO_PRIO_CLASS(bprio);
159
e014ff8d
ON
160 if (aclass == IOPRIO_CLASS_NONE)
161 aclass = IOPRIO_CLASS_BE;
162 if (bclass == IOPRIO_CLASS_NONE)
163 bclass = IOPRIO_CLASS_BE;
164
165 if (aclass == bclass)
166 return min(aprio, bprio);
167 if (aclass > bclass)
168 return bprio;
169 else
170 return aprio;
171}
172
938bb9f5 173SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
22e2c507
JA
174{
175 struct task_struct *g, *p;
176 struct user_struct *user;
41487c65 177 struct pid *pgrp;
22e2c507 178 int ret = -ESRCH;
a1836a42 179 int tmpio;
22e2c507 180
d69b78ba 181 rcu_read_lock();
22e2c507
JA
182 switch (which) {
183 case IOPRIO_WHO_PROCESS:
184 if (!who)
185 p = current;
186 else
228ebcbe 187 p = find_task_by_vpid(who);
22e2c507 188 if (p)
a1836a42 189 ret = get_task_ioprio(p);
22e2c507
JA
190 break;
191 case IOPRIO_WHO_PGRP:
192 if (!who)
41487c65
EB
193 pgrp = task_pgrp(current);
194 else
b488893a 195 pgrp = find_vpid(who);
2d70b68d 196 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
a1836a42
DQ
197 tmpio = get_task_ioprio(p);
198 if (tmpio < 0)
199 continue;
22e2c507 200 if (ret == -ESRCH)
a1836a42 201 ret = tmpio;
22e2c507 202 else
a1836a42 203 ret = ioprio_best(ret, tmpio);
2d70b68d 204 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
22e2c507
JA
205 break;
206 case IOPRIO_WHO_USER:
207 if (!who)
86a264ab 208 user = current_user();
22e2c507
JA
209 else
210 user = find_user(who);
211
212 if (!user)
213 break;
214
215 do_each_thread(g, p) {
d69b78ba 216 if (__task_cred(p)->uid != user->uid)
22e2c507 217 continue;
a1836a42
DQ
218 tmpio = get_task_ioprio(p);
219 if (tmpio < 0)
220 continue;
22e2c507 221 if (ret == -ESRCH)
a1836a42 222 ret = tmpio;
22e2c507 223 else
a1836a42 224 ret = ioprio_best(ret, tmpio);
22e2c507
JA
225 } while_each_thread(g, p);
226
227 if (who)
228 free_uid(user);
229 break;
230 default:
231 ret = -EINVAL;
232 }
233
d69b78ba 234 rcu_read_unlock();
22e2c507
JA
235 return ret;
236}