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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> |
8703e8a4 | 28 | #include <linux/sched/user.h> |
9abdc4cd | 29 | #include <linux/syscalls.h> |
03e68060 | 30 | #include <linux/security.h> |
b488893a | 31 | #include <linux/pid_namespace.h> |
22e2c507 | 32 | |
b3881f74 | 33 | int set_task_ioprio(struct task_struct *task, int ioprio) |
22e2c507 | 34 | { |
03e68060 | 35 | int err; |
22e2c507 | 36 | struct io_context *ioc; |
c69e8d9c | 37 | const struct cred *cred = current_cred(), *tcred; |
22e2c507 | 38 | |
c69e8d9c DH |
39 | rcu_read_lock(); |
40 | tcred = __task_cred(task); | |
8e96e3b7 EB |
41 | if (!uid_eq(tcred->uid, cred->euid) && |
42 | !uid_eq(tcred->uid, cred->uid) && !capable(CAP_SYS_NICE)) { | |
c69e8d9c | 43 | rcu_read_unlock(); |
22e2c507 | 44 | return -EPERM; |
c69e8d9c DH |
45 | } |
46 | rcu_read_unlock(); | |
22e2c507 | 47 | |
03e68060 JM |
48 | err = security_task_setioprio(task, ioprio); |
49 | if (err) | |
50 | return err; | |
51 | ||
6e736be7 TH |
52 | ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE); |
53 | if (ioc) { | |
2b566fa5 | 54 | ioc->ioprio = ioprio; |
11a3122f | 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; |
7b44ab97 | 69 | kuid_t uid; |
22e2c507 JA |
70 | int ret; |
71 | ||
72 | switch (class) { | |
73 | case IOPRIO_CLASS_RT: | |
74 | if (!capable(CAP_SYS_ADMIN)) | |
75 | return -EPERM; | |
76 | /* fall through, rt has prio field too */ | |
77 | case IOPRIO_CLASS_BE: | |
78 | if (data >= IOPRIO_BE_NR || data < 0) | |
79 | return -EINVAL; | |
80 | ||
81 | break; | |
82 | case IOPRIO_CLASS_IDLE: | |
83 | break; | |
8ec680e4 JA |
84 | case IOPRIO_CLASS_NONE: |
85 | if (data) | |
86 | return -EINVAL; | |
87 | break; | |
22e2c507 JA |
88 | default: |
89 | return -EINVAL; | |
90 | } | |
91 | ||
92 | ret = -ESRCH; | |
d69b78ba | 93 | rcu_read_lock(); |
22e2c507 JA |
94 | switch (which) { |
95 | case IOPRIO_WHO_PROCESS: | |
96 | if (!who) | |
97 | p = current; | |
98 | else | |
228ebcbe | 99 | p = find_task_by_vpid(who); |
22e2c507 JA |
100 | if (p) |
101 | ret = set_task_ioprio(p, ioprio); | |
102 | break; | |
103 | case IOPRIO_WHO_PGRP: | |
104 | if (!who) | |
41487c65 EB |
105 | pgrp = task_pgrp(current); |
106 | else | |
b488893a | 107 | pgrp = find_vpid(who); |
2d70b68d | 108 | do_each_pid_thread(pgrp, PIDTYPE_PGID, p) { |
22e2c507 JA |
109 | ret = set_task_ioprio(p, ioprio); |
110 | if (ret) | |
111 | break; | |
2d70b68d | 112 | } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); |
22e2c507 JA |
113 | break; |
114 | case IOPRIO_WHO_USER: | |
7b44ab97 EB |
115 | uid = make_kuid(current_user_ns(), who); |
116 | if (!uid_valid(uid)) | |
117 | break; | |
22e2c507 | 118 | if (!who) |
86a264ab | 119 | user = current_user(); |
22e2c507 | 120 | else |
7b44ab97 | 121 | user = find_user(uid); |
22e2c507 JA |
122 | |
123 | if (!user) | |
124 | break; | |
125 | ||
612dafab | 126 | for_each_process_thread(g, p) { |
8639b461 BS |
127 | if (!uid_eq(task_uid(p), uid) || |
128 | !task_pid_vnr(p)) | |
22e2c507 JA |
129 | continue; |
130 | ret = set_task_ioprio(p, ioprio); | |
131 | if (ret) | |
78bd4d48 | 132 | goto free_uid; |
612dafab | 133 | } |
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 | 153 | ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM); |
8ba86821 | 154 | task_lock(p); |
fd0928df JA |
155 | if (p->io_context) |
156 | ret = p->io_context->ioprio; | |
8ba86821 | 157 | task_unlock(p); |
a1836a42 DQ |
158 | out: |
159 | return ret; | |
160 | } | |
161 | ||
e014ff8d ON |
162 | int ioprio_best(unsigned short aprio, unsigned short bprio) |
163 | { | |
ece9c72a JK |
164 | unsigned short aclass; |
165 | unsigned short bclass; | |
e014ff8d | 166 | |
ece9c72a JK |
167 | if (!ioprio_valid(aprio)) |
168 | aprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM); | |
169 | if (!ioprio_valid(bprio)) | |
170 | bprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM); | |
e014ff8d | 171 | |
ece9c72a JK |
172 | aclass = IOPRIO_PRIO_CLASS(aprio); |
173 | bclass = IOPRIO_PRIO_CLASS(bprio); | |
e014ff8d ON |
174 | if (aclass == bclass) |
175 | return min(aprio, bprio); | |
176 | if (aclass > bclass) | |
177 | return bprio; | |
178 | else | |
179 | return aprio; | |
180 | } | |
181 | ||
938bb9f5 | 182 | SYSCALL_DEFINE2(ioprio_get, int, which, int, who) |
22e2c507 JA |
183 | { |
184 | struct task_struct *g, *p; | |
185 | struct user_struct *user; | |
41487c65 | 186 | struct pid *pgrp; |
7b44ab97 | 187 | kuid_t uid; |
22e2c507 | 188 | int ret = -ESRCH; |
a1836a42 | 189 | int tmpio; |
22e2c507 | 190 | |
d69b78ba | 191 | rcu_read_lock(); |
22e2c507 JA |
192 | switch (which) { |
193 | case IOPRIO_WHO_PROCESS: | |
194 | if (!who) | |
195 | p = current; | |
196 | else | |
228ebcbe | 197 | p = find_task_by_vpid(who); |
22e2c507 | 198 | if (p) |
a1836a42 | 199 | ret = get_task_ioprio(p); |
22e2c507 JA |
200 | break; |
201 | case IOPRIO_WHO_PGRP: | |
202 | if (!who) | |
41487c65 EB |
203 | pgrp = task_pgrp(current); |
204 | else | |
b488893a | 205 | pgrp = find_vpid(who); |
2d70b68d | 206 | do_each_pid_thread(pgrp, PIDTYPE_PGID, p) { |
a1836a42 DQ |
207 | tmpio = get_task_ioprio(p); |
208 | if (tmpio < 0) | |
209 | continue; | |
22e2c507 | 210 | if (ret == -ESRCH) |
a1836a42 | 211 | ret = tmpio; |
22e2c507 | 212 | else |
a1836a42 | 213 | ret = ioprio_best(ret, tmpio); |
2d70b68d | 214 | } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); |
22e2c507 JA |
215 | break; |
216 | case IOPRIO_WHO_USER: | |
7b44ab97 | 217 | uid = make_kuid(current_user_ns(), who); |
22e2c507 | 218 | if (!who) |
86a264ab | 219 | user = current_user(); |
22e2c507 | 220 | else |
7b44ab97 | 221 | user = find_user(uid); |
22e2c507 JA |
222 | |
223 | if (!user) | |
224 | break; | |
225 | ||
612dafab | 226 | for_each_process_thread(g, p) { |
8639b461 BS |
227 | if (!uid_eq(task_uid(p), user->uid) || |
228 | !task_pid_vnr(p)) | |
22e2c507 | 229 | continue; |
a1836a42 DQ |
230 | tmpio = get_task_ioprio(p); |
231 | if (tmpio < 0) | |
232 | continue; | |
22e2c507 | 233 | if (ret == -ESRCH) |
a1836a42 | 234 | ret = tmpio; |
22e2c507 | 235 | else |
a1836a42 | 236 | ret = ioprio_best(ret, tmpio); |
612dafab | 237 | } |
22e2c507 JA |
238 | |
239 | if (who) | |
240 | free_uid(user); | |
241 | break; | |
242 | default: | |
243 | ret = -EINVAL; | |
244 | } | |
245 | ||
d69b78ba | 246 | rcu_read_unlock(); |
22e2c507 JA |
247 | return ret; |
248 | } |