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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 | 32 | int 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 | 60 | EXPORT_SYMBOL_GPL(set_task_ioprio); |
22e2c507 | 61 | |
938bb9f5 | 62 | SYSCALL_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); |
22e2c507 JA |
112 | break; |
113 | case IOPRIO_WHO_USER: | |
114 | if (!who) | |
86a264ab | 115 | user = current_user(); |
22e2c507 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 | 129 | free_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 |
141 | static 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 |
151 | out: |
152 | return ret; | |
153 | } | |
154 | ||
e014ff8d ON |
155 | int 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 | 173 | SYSCALL_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 | } |