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1 | /* | |
2 | * fs/ioprio.c | |
3 | * | |
4 | * Copyright (C) 2004 Jens Axboe <axboe@kernel.dk> | |
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/gfp.h> | |
23 | #include <linux/kernel.h> | |
24 | #include <linux/export.h> | |
25 | #include <linux/ioprio.h> | |
26 | #include <linux/blkdev.h> | |
27 | #include <linux/capability.h> | |
28 | #include <linux/syscalls.h> | |
29 | #include <linux/security.h> | |
30 | #include <linux/pid_namespace.h> | |
31 | ||
32 | int set_task_ioprio(struct task_struct *task, int ioprio) | |
33 | { | |
34 | int err; | |
35 | struct io_context *ioc; | |
36 | const struct cred *cred = current_cred(), *tcred; | |
37 | ||
38 | rcu_read_lock(); | |
39 | tcred = __task_cred(task); | |
40 | if (!uid_eq(tcred->uid, cred->euid) && | |
41 | !uid_eq(tcred->uid, cred->uid) && !capable(CAP_SYS_NICE)) { | |
42 | rcu_read_unlock(); | |
43 | return -EPERM; | |
44 | } | |
45 | rcu_read_unlock(); | |
46 | ||
47 | err = security_task_setioprio(task, ioprio); | |
48 | if (err) | |
49 | return err; | |
50 | ||
51 | ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE); | |
52 | if (ioc) { | |
53 | ioc->ioprio = ioprio; | |
54 | put_io_context(ioc); | |
55 | } | |
56 | ||
57 | return err; | |
58 | } | |
59 | EXPORT_SYMBOL_GPL(set_task_ioprio); | |
60 | ||
61 | SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio) | |
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; | |
67 | struct pid *pgrp; | |
68 | kuid_t uid; | |
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; | |
83 | case IOPRIO_CLASS_NONE: | |
84 | if (data) | |
85 | return -EINVAL; | |
86 | break; | |
87 | default: | |
88 | return -EINVAL; | |
89 | } | |
90 | ||
91 | ret = -ESRCH; | |
92 | rcu_read_lock(); | |
93 | switch (which) { | |
94 | case IOPRIO_WHO_PROCESS: | |
95 | if (!who) | |
96 | p = current; | |
97 | else | |
98 | p = find_task_by_vpid(who); | |
99 | if (p) | |
100 | ret = set_task_ioprio(p, ioprio); | |
101 | break; | |
102 | case IOPRIO_WHO_PGRP: | |
103 | if (!who) | |
104 | pgrp = task_pgrp(current); | |
105 | else | |
106 | pgrp = find_vpid(who); | |
107 | do_each_pid_thread(pgrp, PIDTYPE_PGID, p) { | |
108 | ret = set_task_ioprio(p, ioprio); | |
109 | if (ret) | |
110 | break; | |
111 | } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); | |
112 | break; | |
113 | case IOPRIO_WHO_USER: | |
114 | uid = make_kuid(current_user_ns(), who); | |
115 | if (!uid_valid(uid)) | |
116 | break; | |
117 | if (!who) | |
118 | user = current_user(); | |
119 | else | |
120 | user = find_user(uid); | |
121 | ||
122 | if (!user) | |
123 | break; | |
124 | ||
125 | do_each_thread(g, p) { | |
126 | if (!uid_eq(task_uid(p), uid) || | |
127 | !task_pid_vnr(p)) | |
128 | continue; | |
129 | ret = set_task_ioprio(p, ioprio); | |
130 | if (ret) | |
131 | goto free_uid; | |
132 | } while_each_thread(g, p); | |
133 | free_uid: | |
134 | if (who) | |
135 | free_uid(user); | |
136 | break; | |
137 | default: | |
138 | ret = -EINVAL; | |
139 | } | |
140 | ||
141 | rcu_read_unlock(); | |
142 | return ret; | |
143 | } | |
144 | ||
145 | static int get_task_ioprio(struct task_struct *p) | |
146 | { | |
147 | int ret; | |
148 | ||
149 | ret = security_task_getioprio(p); | |
150 | if (ret) | |
151 | goto out; | |
152 | ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM); | |
153 | task_lock(p); | |
154 | if (p->io_context) | |
155 | ret = p->io_context->ioprio; | |
156 | task_unlock(p); | |
157 | out: | |
158 | return ret; | |
159 | } | |
160 | ||
161 | int ioprio_best(unsigned short aprio, unsigned short bprio) | |
162 | { | |
163 | unsigned short aclass; | |
164 | unsigned short bclass; | |
165 | ||
166 | if (!ioprio_valid(aprio)) | |
167 | aprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM); | |
168 | if (!ioprio_valid(bprio)) | |
169 | bprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM); | |
170 | ||
171 | aclass = IOPRIO_PRIO_CLASS(aprio); | |
172 | bclass = IOPRIO_PRIO_CLASS(bprio); | |
173 | if (aclass == bclass) | |
174 | return min(aprio, bprio); | |
175 | if (aclass > bclass) | |
176 | return bprio; | |
177 | else | |
178 | return aprio; | |
179 | } | |
180 | ||
181 | SYSCALL_DEFINE2(ioprio_get, int, which, int, who) | |
182 | { | |
183 | struct task_struct *g, *p; | |
184 | struct user_struct *user; | |
185 | struct pid *pgrp; | |
186 | kuid_t uid; | |
187 | int ret = -ESRCH; | |
188 | int tmpio; | |
189 | ||
190 | rcu_read_lock(); | |
191 | switch (which) { | |
192 | case IOPRIO_WHO_PROCESS: | |
193 | if (!who) | |
194 | p = current; | |
195 | else | |
196 | p = find_task_by_vpid(who); | |
197 | if (p) | |
198 | ret = get_task_ioprio(p); | |
199 | break; | |
200 | case IOPRIO_WHO_PGRP: | |
201 | if (!who) | |
202 | pgrp = task_pgrp(current); | |
203 | else | |
204 | pgrp = find_vpid(who); | |
205 | do_each_pid_thread(pgrp, PIDTYPE_PGID, p) { | |
206 | tmpio = get_task_ioprio(p); | |
207 | if (tmpio < 0) | |
208 | continue; | |
209 | if (ret == -ESRCH) | |
210 | ret = tmpio; | |
211 | else | |
212 | ret = ioprio_best(ret, tmpio); | |
213 | } while_each_pid_thread(pgrp, PIDTYPE_PGID, p); | |
214 | break; | |
215 | case IOPRIO_WHO_USER: | |
216 | uid = make_kuid(current_user_ns(), who); | |
217 | if (!who) | |
218 | user = current_user(); | |
219 | else | |
220 | user = find_user(uid); | |
221 | ||
222 | if (!user) | |
223 | break; | |
224 | ||
225 | do_each_thread(g, p) { | |
226 | if (!uid_eq(task_uid(p), user->uid) || | |
227 | !task_pid_vnr(p)) | |
228 | continue; | |
229 | tmpio = get_task_ioprio(p); | |
230 | if (tmpio < 0) | |
231 | continue; | |
232 | if (ret == -ESRCH) | |
233 | ret = tmpio; | |
234 | else | |
235 | ret = ioprio_best(ret, tmpio); | |
236 | } while_each_thread(g, p); | |
237 | ||
238 | if (who) | |
239 | free_uid(user); | |
240 | break; | |
241 | default: | |
242 | ret = -EINVAL; | |
243 | } | |
244 | ||
245 | rcu_read_unlock(); | |
246 | return ret; | |
247 | } |