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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 | */ | |
22 | #include <linux/kernel.h> | |
23 | #include <linux/ioprio.h> | |
24 | #include <linux/blkdev.h> | |
16f7e0fe | 25 | #include <linux/capability.h> |
9abdc4cd | 26 | #include <linux/syscalls.h> |
03e68060 | 27 | #include <linux/security.h> |
b488893a | 28 | #include <linux/pid_namespace.h> |
22e2c507 JA |
29 | |
30 | static int set_task_ioprio(struct task_struct *task, int ioprio) | |
31 | { | |
03e68060 | 32 | int err; |
22e2c507 JA |
33 | struct io_context *ioc; |
34 | ||
35 | if (task->uid != current->euid && | |
36 | task->uid != current->uid && !capable(CAP_SYS_NICE)) | |
37 | return -EPERM; | |
38 | ||
03e68060 JM |
39 | err = security_task_setioprio(task, ioprio); |
40 | if (err) | |
41 | return err; | |
42 | ||
22e2c507 JA |
43 | task_lock(task); |
44 | ||
45 | task->ioprio = ioprio; | |
46 | ||
47 | ioc = task->io_context; | |
9f83e45e ON |
48 | /* see wmb() in current_io_context() */ |
49 | smp_read_barrier_depends(); | |
50 | ||
fc46379d JA |
51 | if (ioc) |
52 | ioc->ioprio_changed = 1; | |
22e2c507 JA |
53 | |
54 | task_unlock(task); | |
55 | return 0; | |
56 | } | |
57 | ||
cf366808 | 58 | asmlinkage long sys_ioprio_set(int which, int who, int ioprio) |
22e2c507 JA |
59 | { |
60 | int class = IOPRIO_PRIO_CLASS(ioprio); | |
61 | int data = IOPRIO_PRIO_DATA(ioprio); | |
62 | struct task_struct *p, *g; | |
63 | struct user_struct *user; | |
41487c65 | 64 | struct pid *pgrp; |
22e2c507 JA |
65 | int ret; |
66 | ||
67 | switch (class) { | |
68 | case IOPRIO_CLASS_RT: | |
69 | if (!capable(CAP_SYS_ADMIN)) | |
70 | return -EPERM; | |
71 | /* fall through, rt has prio field too */ | |
72 | case IOPRIO_CLASS_BE: | |
73 | if (data >= IOPRIO_BE_NR || data < 0) | |
74 | return -EINVAL; | |
75 | ||
76 | break; | |
77 | case IOPRIO_CLASS_IDLE: | |
f6fdd7d9 LT |
78 | if (!capable(CAP_SYS_ADMIN)) |
79 | return -EPERM; | |
22e2c507 JA |
80 | break; |
81 | default: | |
82 | return -EINVAL; | |
83 | } | |
84 | ||
85 | ret = -ESRCH; | |
cf342e52 ON |
86 | /* |
87 | * We want IOPRIO_WHO_PGRP/IOPRIO_WHO_USER to be "atomic", | |
88 | * so we can't use rcu_read_lock(). See re-copy of ->ioprio | |
89 | * in copy_process(). | |
90 | */ | |
91 | read_lock(&tasklist_lock); | |
22e2c507 JA |
92 | switch (which) { |
93 | case IOPRIO_WHO_PROCESS: | |
94 | if (!who) | |
95 | p = current; | |
96 | else | |
228ebcbe | 97 | p = find_task_by_vpid(who); |
22e2c507 JA |
98 | if (p) |
99 | ret = set_task_ioprio(p, ioprio); | |
100 | break; | |
101 | case IOPRIO_WHO_PGRP: | |
102 | if (!who) | |
41487c65 EB |
103 | pgrp = task_pgrp(current); |
104 | else | |
b488893a | 105 | pgrp = find_vpid(who); |
41487c65 | 106 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
22e2c507 JA |
107 | ret = set_task_ioprio(p, ioprio); |
108 | if (ret) | |
109 | break; | |
41487c65 | 110 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
22e2c507 JA |
111 | break; |
112 | case IOPRIO_WHO_USER: | |
113 | if (!who) | |
114 | user = current->user; | |
115 | else | |
116 | user = find_user(who); | |
117 | ||
118 | if (!user) | |
119 | break; | |
120 | ||
121 | do_each_thread(g, p) { | |
122 | if (p->uid != who) | |
123 | continue; | |
124 | ret = set_task_ioprio(p, ioprio); | |
125 | if (ret) | |
78bd4d48 | 126 | goto free_uid; |
22e2c507 | 127 | } while_each_thread(g, p); |
78bd4d48 | 128 | free_uid: |
22e2c507 JA |
129 | if (who) |
130 | free_uid(user); | |
131 | break; | |
132 | default: | |
133 | ret = -EINVAL; | |
134 | } | |
135 | ||
cf342e52 | 136 | read_unlock(&tasklist_lock); |
22e2c507 JA |
137 | return ret; |
138 | } | |
139 | ||
a1836a42 DQ |
140 | static int get_task_ioprio(struct task_struct *p) |
141 | { | |
142 | int ret; | |
143 | ||
144 | ret = security_task_getioprio(p); | |
145 | if (ret) | |
146 | goto out; | |
147 | ret = p->ioprio; | |
148 | out: | |
149 | return ret; | |
150 | } | |
151 | ||
e014ff8d ON |
152 | int ioprio_best(unsigned short aprio, unsigned short bprio) |
153 | { | |
154 | unsigned short aclass = IOPRIO_PRIO_CLASS(aprio); | |
155 | unsigned short bclass = IOPRIO_PRIO_CLASS(bprio); | |
156 | ||
e014ff8d ON |
157 | if (aclass == IOPRIO_CLASS_NONE) |
158 | aclass = IOPRIO_CLASS_BE; | |
159 | if (bclass == IOPRIO_CLASS_NONE) | |
160 | bclass = IOPRIO_CLASS_BE; | |
161 | ||
162 | if (aclass == bclass) | |
163 | return min(aprio, bprio); | |
164 | if (aclass > bclass) | |
165 | return bprio; | |
166 | else | |
167 | return aprio; | |
168 | } | |
169 | ||
cf366808 | 170 | asmlinkage long sys_ioprio_get(int which, int who) |
22e2c507 JA |
171 | { |
172 | struct task_struct *g, *p; | |
173 | struct user_struct *user; | |
41487c65 | 174 | struct pid *pgrp; |
22e2c507 | 175 | int ret = -ESRCH; |
a1836a42 | 176 | int tmpio; |
22e2c507 | 177 | |
cf342e52 | 178 | read_lock(&tasklist_lock); |
22e2c507 JA |
179 | switch (which) { |
180 | case IOPRIO_WHO_PROCESS: | |
181 | if (!who) | |
182 | p = current; | |
183 | else | |
228ebcbe | 184 | p = find_task_by_vpid(who); |
22e2c507 | 185 | if (p) |
a1836a42 | 186 | ret = get_task_ioprio(p); |
22e2c507 JA |
187 | break; |
188 | case IOPRIO_WHO_PGRP: | |
189 | if (!who) | |
41487c65 EB |
190 | pgrp = task_pgrp(current); |
191 | else | |
b488893a | 192 | pgrp = find_vpid(who); |
41487c65 | 193 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
a1836a42 DQ |
194 | tmpio = get_task_ioprio(p); |
195 | if (tmpio < 0) | |
196 | continue; | |
22e2c507 | 197 | if (ret == -ESRCH) |
a1836a42 | 198 | ret = tmpio; |
22e2c507 | 199 | else |
a1836a42 | 200 | ret = ioprio_best(ret, tmpio); |
41487c65 | 201 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
22e2c507 JA |
202 | break; |
203 | case IOPRIO_WHO_USER: | |
204 | if (!who) | |
205 | user = current->user; | |
206 | else | |
207 | user = find_user(who); | |
208 | ||
209 | if (!user) | |
210 | break; | |
211 | ||
212 | do_each_thread(g, p) { | |
213 | if (p->uid != user->uid) | |
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); |
22e2c507 JA |
222 | } while_each_thread(g, p); |
223 | ||
224 | if (who) | |
225 | free_uid(user); | |
226 | break; | |
227 | default: | |
228 | ret = -EINVAL; | |
229 | } | |
230 | ||
cf342e52 | 231 | read_unlock(&tasklist_lock); |
22e2c507 JA |
232 | return ret; |
233 | } | |
234 |