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Commit | Line | Data |
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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 | 43 | task_lock(task); |
fd0928df JA |
44 | do { |
45 | ioc = task->io_context; | |
46 | /* see wmb() in current_io_context() */ | |
47 | smp_read_barrier_depends(); | |
48 | if (ioc) | |
49 | break; | |
22e2c507 | 50 | |
fd0928df JA |
51 | ioc = alloc_io_context(GFP_ATOMIC, -1); |
52 | if (!ioc) { | |
53 | err = -ENOMEM; | |
54 | break; | |
55 | } | |
56 | task->io_context = ioc; | |
57 | ioc->task = task; | |
58 | } while (1); | |
9f83e45e | 59 | |
fd0928df JA |
60 | if (!err) { |
61 | ioc->ioprio = ioprio; | |
fc46379d | 62 | ioc->ioprio_changed = 1; |
fd0928df | 63 | } |
22e2c507 JA |
64 | |
65 | task_unlock(task); | |
fd0928df | 66 | return err; |
22e2c507 JA |
67 | } |
68 | ||
cf366808 | 69 | asmlinkage long sys_ioprio_set(int which, int who, int ioprio) |
22e2c507 JA |
70 | { |
71 | int class = IOPRIO_PRIO_CLASS(ioprio); | |
72 | int data = IOPRIO_PRIO_DATA(ioprio); | |
73 | struct task_struct *p, *g; | |
74 | struct user_struct *user; | |
41487c65 | 75 | struct pid *pgrp; |
22e2c507 JA |
76 | int ret; |
77 | ||
78 | switch (class) { | |
79 | case IOPRIO_CLASS_RT: | |
80 | if (!capable(CAP_SYS_ADMIN)) | |
81 | return -EPERM; | |
82 | /* fall through, rt has prio field too */ | |
83 | case IOPRIO_CLASS_BE: | |
84 | if (data >= IOPRIO_BE_NR || data < 0) | |
85 | return -EINVAL; | |
86 | ||
87 | break; | |
88 | case IOPRIO_CLASS_IDLE: | |
f6fdd7d9 LT |
89 | if (!capable(CAP_SYS_ADMIN)) |
90 | return -EPERM; | |
22e2c507 | 91 | break; |
8ec680e4 JA |
92 | case IOPRIO_CLASS_NONE: |
93 | if (data) | |
94 | return -EINVAL; | |
95 | break; | |
22e2c507 JA |
96 | default: |
97 | return -EINVAL; | |
98 | } | |
99 | ||
100 | ret = -ESRCH; | |
cf342e52 ON |
101 | /* |
102 | * We want IOPRIO_WHO_PGRP/IOPRIO_WHO_USER to be "atomic", | |
103 | * so we can't use rcu_read_lock(). See re-copy of ->ioprio | |
104 | * in copy_process(). | |
105 | */ | |
106 | read_lock(&tasklist_lock); | |
22e2c507 JA |
107 | switch (which) { |
108 | case IOPRIO_WHO_PROCESS: | |
109 | if (!who) | |
110 | p = current; | |
111 | else | |
228ebcbe | 112 | p = find_task_by_vpid(who); |
22e2c507 JA |
113 | if (p) |
114 | ret = set_task_ioprio(p, ioprio); | |
115 | break; | |
116 | case IOPRIO_WHO_PGRP: | |
117 | if (!who) | |
41487c65 EB |
118 | pgrp = task_pgrp(current); |
119 | else | |
b488893a | 120 | pgrp = find_vpid(who); |
41487c65 | 121 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
22e2c507 JA |
122 | ret = set_task_ioprio(p, ioprio); |
123 | if (ret) | |
124 | break; | |
41487c65 | 125 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
22e2c507 JA |
126 | break; |
127 | case IOPRIO_WHO_USER: | |
128 | if (!who) | |
129 | user = current->user; | |
130 | else | |
131 | user = find_user(who); | |
132 | ||
133 | if (!user) | |
134 | break; | |
135 | ||
136 | do_each_thread(g, p) { | |
137 | if (p->uid != who) | |
138 | continue; | |
139 | ret = set_task_ioprio(p, ioprio); | |
140 | if (ret) | |
78bd4d48 | 141 | goto free_uid; |
22e2c507 | 142 | } while_each_thread(g, p); |
78bd4d48 | 143 | free_uid: |
22e2c507 JA |
144 | if (who) |
145 | free_uid(user); | |
146 | break; | |
147 | default: | |
148 | ret = -EINVAL; | |
149 | } | |
150 | ||
cf342e52 | 151 | read_unlock(&tasklist_lock); |
22e2c507 JA |
152 | return ret; |
153 | } | |
154 | ||
a1836a42 DQ |
155 | static int get_task_ioprio(struct task_struct *p) |
156 | { | |
157 | int ret; | |
158 | ||
159 | ret = security_task_getioprio(p); | |
160 | if (ret) | |
161 | goto out; | |
fd0928df JA |
162 | ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM); |
163 | if (p->io_context) | |
164 | ret = p->io_context->ioprio; | |
a1836a42 DQ |
165 | out: |
166 | return ret; | |
167 | } | |
168 | ||
e014ff8d ON |
169 | int ioprio_best(unsigned short aprio, unsigned short bprio) |
170 | { | |
171 | unsigned short aclass = IOPRIO_PRIO_CLASS(aprio); | |
172 | unsigned short bclass = IOPRIO_PRIO_CLASS(bprio); | |
173 | ||
e014ff8d ON |
174 | if (aclass == IOPRIO_CLASS_NONE) |
175 | aclass = IOPRIO_CLASS_BE; | |
176 | if (bclass == IOPRIO_CLASS_NONE) | |
177 | bclass = IOPRIO_CLASS_BE; | |
178 | ||
179 | if (aclass == bclass) | |
180 | return min(aprio, bprio); | |
181 | if (aclass > bclass) | |
182 | return bprio; | |
183 | else | |
184 | return aprio; | |
185 | } | |
186 | ||
cf366808 | 187 | asmlinkage long sys_ioprio_get(int which, int who) |
22e2c507 JA |
188 | { |
189 | struct task_struct *g, *p; | |
190 | struct user_struct *user; | |
41487c65 | 191 | struct pid *pgrp; |
22e2c507 | 192 | int ret = -ESRCH; |
a1836a42 | 193 | int tmpio; |
22e2c507 | 194 | |
cf342e52 | 195 | read_lock(&tasklist_lock); |
22e2c507 JA |
196 | switch (which) { |
197 | case IOPRIO_WHO_PROCESS: | |
198 | if (!who) | |
199 | p = current; | |
200 | else | |
228ebcbe | 201 | p = find_task_by_vpid(who); |
22e2c507 | 202 | if (p) |
a1836a42 | 203 | ret = get_task_ioprio(p); |
22e2c507 JA |
204 | break; |
205 | case IOPRIO_WHO_PGRP: | |
206 | if (!who) | |
41487c65 EB |
207 | pgrp = task_pgrp(current); |
208 | else | |
b488893a | 209 | pgrp = find_vpid(who); |
41487c65 | 210 | do_each_pid_task(pgrp, PIDTYPE_PGID, p) { |
a1836a42 DQ |
211 | tmpio = get_task_ioprio(p); |
212 | if (tmpio < 0) | |
213 | continue; | |
22e2c507 | 214 | if (ret == -ESRCH) |
a1836a42 | 215 | ret = tmpio; |
22e2c507 | 216 | else |
a1836a42 | 217 | ret = ioprio_best(ret, tmpio); |
41487c65 | 218 | } while_each_pid_task(pgrp, PIDTYPE_PGID, p); |
22e2c507 JA |
219 | break; |
220 | case IOPRIO_WHO_USER: | |
221 | if (!who) | |
222 | user = current->user; | |
223 | else | |
224 | user = find_user(who); | |
225 | ||
226 | if (!user) | |
227 | break; | |
228 | ||
229 | do_each_thread(g, p) { | |
230 | if (p->uid != user->uid) | |
231 | continue; | |
a1836a42 DQ |
232 | tmpio = get_task_ioprio(p); |
233 | if (tmpio < 0) | |
234 | continue; | |
22e2c507 | 235 | if (ret == -ESRCH) |
a1836a42 | 236 | ret = tmpio; |
22e2c507 | 237 | else |
a1836a42 | 238 | ret = ioprio_best(ret, tmpio); |
22e2c507 JA |
239 | } while_each_thread(g, p); |
240 | ||
241 | if (who) | |
242 | free_uid(user); | |
243 | break; | |
244 | default: | |
245 | ret = -EINVAL; | |
246 | } | |
247 | ||
cf342e52 | 248 | read_unlock(&tasklist_lock); |
22e2c507 JA |
249 | return ret; |
250 | } | |
251 |