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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) { | |
dc86900e | 53 | ioc_ioprio_changed(ioc, ioprio); |
11a3122f | 54 | put_io_context(ioc); |
fd0928df | 55 | } |
22e2c507 | 56 | |
fd0928df | 57 | return err; |
22e2c507 | 58 | } |
b3881f74 | 59 | EXPORT_SYMBOL_GPL(set_task_ioprio); |
22e2c507 | 60 | |
938bb9f5 | 61 | SYSCALL_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) { | |
7b44ab97 EB |
126 | const struct cred *tcred = __task_cred(p); |
127 | kuid_t tcred_uid = make_kuid(tcred->user_ns, tcred->uid); | |
128 | if (!uid_eq(tcred_uid, uid)) | |
22e2c507 JA |
129 | continue; |
130 | ret = set_task_ioprio(p, ioprio); | |
131 | if (ret) | |
78bd4d48 | 132 | goto free_uid; |
22e2c507 | 133 | } while_each_thread(g, p); |
78bd4d48 | 134 | free_uid: |
22e2c507 JA |
135 | if (who) |
136 | free_uid(user); | |
137 | break; | |
138 | default: | |
139 | ret = -EINVAL; | |
140 | } | |
141 | ||
d69b78ba | 142 | rcu_read_unlock(); |
22e2c507 JA |
143 | return ret; |
144 | } | |
145 | ||
a1836a42 DQ |
146 | static int get_task_ioprio(struct task_struct *p) |
147 | { | |
148 | int ret; | |
149 | ||
150 | ret = security_task_getioprio(p); | |
151 | if (ret) | |
152 | goto out; | |
fd0928df JA |
153 | ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM); |
154 | if (p->io_context) | |
155 | ret = p->io_context->ioprio; | |
a1836a42 DQ |
156 | out: |
157 | return ret; | |
158 | } | |
159 | ||
e014ff8d ON |
160 | int ioprio_best(unsigned short aprio, unsigned short bprio) |
161 | { | |
162 | unsigned short aclass = IOPRIO_PRIO_CLASS(aprio); | |
163 | unsigned short bclass = IOPRIO_PRIO_CLASS(bprio); | |
164 | ||
e014ff8d ON |
165 | if (aclass == IOPRIO_CLASS_NONE) |
166 | aclass = IOPRIO_CLASS_BE; | |
167 | if (bclass == IOPRIO_CLASS_NONE) | |
168 | bclass = IOPRIO_CLASS_BE; | |
169 | ||
170 | if (aclass == bclass) | |
171 | return min(aprio, bprio); | |
172 | if (aclass > bclass) | |
173 | return bprio; | |
174 | else | |
175 | return aprio; | |
176 | } | |
177 | ||
938bb9f5 | 178 | SYSCALL_DEFINE2(ioprio_get, int, which, int, who) |
22e2c507 JA |
179 | { |
180 | struct task_struct *g, *p; | |
181 | struct user_struct *user; | |
41487c65 | 182 | struct pid *pgrp; |
7b44ab97 | 183 | kuid_t uid; |
22e2c507 | 184 | int ret = -ESRCH; |
a1836a42 | 185 | int tmpio; |
22e2c507 | 186 | |
d69b78ba | 187 | rcu_read_lock(); |
22e2c507 JA |
188 | switch (which) { |
189 | case IOPRIO_WHO_PROCESS: | |
190 | if (!who) | |
191 | p = current; | |
192 | else | |
228ebcbe | 193 | p = find_task_by_vpid(who); |
22e2c507 | 194 | if (p) |
a1836a42 | 195 | ret = get_task_ioprio(p); |
22e2c507 JA |
196 | break; |
197 | case IOPRIO_WHO_PGRP: | |
198 | if (!who) | |
41487c65 EB |
199 | pgrp = task_pgrp(current); |
200 | else | |
b488893a | 201 | pgrp = find_vpid(who); |
2d70b68d | 202 | do_each_pid_thread(pgrp, PIDTYPE_PGID, p) { |
a1836a42 DQ |
203 | tmpio = get_task_ioprio(p); |
204 | if (tmpio < 0) | |
205 | continue; | |
22e2c507 | 206 | if (ret == -ESRCH) |
a1836a42 | 207 | ret = tmpio; |
22e2c507 | 208 | else |
a1836a42 | 209 | ret = ioprio_best(ret, tmpio); |
2d70b68d | 210 | } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); |
22e2c507 JA |
211 | break; |
212 | case IOPRIO_WHO_USER: | |
7b44ab97 | 213 | uid = make_kuid(current_user_ns(), who); |
22e2c507 | 214 | if (!who) |
86a264ab | 215 | user = current_user(); |
22e2c507 | 216 | else |
7b44ab97 | 217 | user = find_user(uid); |
22e2c507 JA |
218 | |
219 | if (!user) | |
220 | break; | |
221 | ||
222 | do_each_thread(g, p) { | |
7b44ab97 EB |
223 | const struct cred *tcred = __task_cred(p); |
224 | kuid_t tcred_uid = make_kuid(tcred->user_ns, tcred->uid); | |
225 | if (!uid_eq(tcred_uid, user->uid)) | |
22e2c507 | 226 | continue; |
a1836a42 DQ |
227 | tmpio = get_task_ioprio(p); |
228 | if (tmpio < 0) | |
229 | continue; | |
22e2c507 | 230 | if (ret == -ESRCH) |
a1836a42 | 231 | ret = tmpio; |
22e2c507 | 232 | else |
a1836a42 | 233 | ret = ioprio_best(ret, tmpio); |
22e2c507 JA |
234 | } while_each_thread(g, p); |
235 | ||
236 | if (who) | |
237 | free_uid(user); | |
238 | break; | |
239 | default: | |
240 | ret = -EINVAL; | |
241 | } | |
242 | ||
d69b78ba | 243 | rcu_read_unlock(); |
22e2c507 JA |
244 | return ret; |
245 | } |