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22e2c507 JA |
1 | /* |
2 | * fs/ioprio.c | |
3 | * | |
4 | * Copyright (C) 2004 Jens Axboe <axboe@suse.de> | |
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> |
22e2c507 JA |
28 | |
29 | static int set_task_ioprio(struct task_struct *task, int ioprio) | |
30 | { | |
03e68060 | 31 | int err; |
22e2c507 JA |
32 | struct io_context *ioc; |
33 | ||
34 | if (task->uid != current->euid && | |
35 | task->uid != current->uid && !capable(CAP_SYS_NICE)) | |
36 | return -EPERM; | |
37 | ||
03e68060 JM |
38 | err = security_task_setioprio(task, ioprio); |
39 | if (err) | |
40 | return err; | |
41 | ||
22e2c507 JA |
42 | task_lock(task); |
43 | ||
44 | task->ioprio = ioprio; | |
45 | ||
46 | ioc = task->io_context; | |
9f83e45e ON |
47 | /* see wmb() in current_io_context() */ |
48 | smp_read_barrier_depends(); | |
49 | ||
22e2c507 JA |
50 | if (ioc && ioc->set_ioprio) |
51 | ioc->set_ioprio(ioc, ioprio); | |
52 | ||
53 | task_unlock(task); | |
54 | return 0; | |
55 | } | |
56 | ||
cf366808 | 57 | asmlinkage long sys_ioprio_set(int which, int who, int ioprio) |
22e2c507 JA |
58 | { |
59 | int class = IOPRIO_PRIO_CLASS(ioprio); | |
60 | int data = IOPRIO_PRIO_DATA(ioprio); | |
61 | struct task_struct *p, *g; | |
62 | struct user_struct *user; | |
63 | int ret; | |
64 | ||
65 | switch (class) { | |
66 | case IOPRIO_CLASS_RT: | |
67 | if (!capable(CAP_SYS_ADMIN)) | |
68 | return -EPERM; | |
69 | /* fall through, rt has prio field too */ | |
70 | case IOPRIO_CLASS_BE: | |
71 | if (data >= IOPRIO_BE_NR || data < 0) | |
72 | return -EINVAL; | |
73 | ||
74 | break; | |
75 | case IOPRIO_CLASS_IDLE: | |
f6fdd7d9 LT |
76 | if (!capable(CAP_SYS_ADMIN)) |
77 | return -EPERM; | |
22e2c507 JA |
78 | break; |
79 | default: | |
80 | return -EINVAL; | |
81 | } | |
82 | ||
83 | ret = -ESRCH; | |
84 | read_lock_irq(&tasklist_lock); | |
85 | switch (which) { | |
86 | case IOPRIO_WHO_PROCESS: | |
87 | if (!who) | |
88 | p = current; | |
89 | else | |
90 | p = find_task_by_pid(who); | |
91 | if (p) | |
92 | ret = set_task_ioprio(p, ioprio); | |
93 | break; | |
94 | case IOPRIO_WHO_PGRP: | |
95 | if (!who) | |
96 | who = process_group(current); | |
97 | do_each_task_pid(who, PIDTYPE_PGID, p) { | |
98 | ret = set_task_ioprio(p, ioprio); | |
99 | if (ret) | |
100 | break; | |
101 | } while_each_task_pid(who, PIDTYPE_PGID, p); | |
102 | break; | |
103 | case IOPRIO_WHO_USER: | |
104 | if (!who) | |
105 | user = current->user; | |
106 | else | |
107 | user = find_user(who); | |
108 | ||
109 | if (!user) | |
110 | break; | |
111 | ||
112 | do_each_thread(g, p) { | |
113 | if (p->uid != who) | |
114 | continue; | |
115 | ret = set_task_ioprio(p, ioprio); | |
116 | if (ret) | |
78bd4d48 | 117 | goto free_uid; |
22e2c507 | 118 | } while_each_thread(g, p); |
78bd4d48 | 119 | free_uid: |
22e2c507 JA |
120 | if (who) |
121 | free_uid(user); | |
122 | break; | |
123 | default: | |
124 | ret = -EINVAL; | |
125 | } | |
126 | ||
127 | read_unlock_irq(&tasklist_lock); | |
128 | return ret; | |
129 | } | |
130 | ||
a1836a42 DQ |
131 | static int get_task_ioprio(struct task_struct *p) |
132 | { | |
133 | int ret; | |
134 | ||
135 | ret = security_task_getioprio(p); | |
136 | if (ret) | |
137 | goto out; | |
138 | ret = p->ioprio; | |
139 | out: | |
140 | return ret; | |
141 | } | |
142 | ||
cf366808 | 143 | asmlinkage long sys_ioprio_get(int which, int who) |
22e2c507 JA |
144 | { |
145 | struct task_struct *g, *p; | |
146 | struct user_struct *user; | |
147 | int ret = -ESRCH; | |
a1836a42 | 148 | int tmpio; |
22e2c507 JA |
149 | |
150 | read_lock_irq(&tasklist_lock); | |
151 | switch (which) { | |
152 | case IOPRIO_WHO_PROCESS: | |
153 | if (!who) | |
154 | p = current; | |
155 | else | |
156 | p = find_task_by_pid(who); | |
157 | if (p) | |
a1836a42 | 158 | ret = get_task_ioprio(p); |
22e2c507 JA |
159 | break; |
160 | case IOPRIO_WHO_PGRP: | |
161 | if (!who) | |
162 | who = process_group(current); | |
163 | do_each_task_pid(who, PIDTYPE_PGID, p) { | |
a1836a42 DQ |
164 | tmpio = get_task_ioprio(p); |
165 | if (tmpio < 0) | |
166 | continue; | |
22e2c507 | 167 | if (ret == -ESRCH) |
a1836a42 | 168 | ret = tmpio; |
22e2c507 | 169 | else |
a1836a42 | 170 | ret = ioprio_best(ret, tmpio); |
22e2c507 JA |
171 | } while_each_task_pid(who, PIDTYPE_PGID, p); |
172 | break; | |
173 | case IOPRIO_WHO_USER: | |
174 | if (!who) | |
175 | user = current->user; | |
176 | else | |
177 | user = find_user(who); | |
178 | ||
179 | if (!user) | |
180 | break; | |
181 | ||
182 | do_each_thread(g, p) { | |
183 | if (p->uid != user->uid) | |
184 | continue; | |
a1836a42 DQ |
185 | tmpio = get_task_ioprio(p); |
186 | if (tmpio < 0) | |
187 | continue; | |
22e2c507 | 188 | if (ret == -ESRCH) |
a1836a42 | 189 | ret = tmpio; |
22e2c507 | 190 | else |
a1836a42 | 191 | ret = ioprio_best(ret, tmpio); |
22e2c507 JA |
192 | } while_each_thread(g, p); |
193 | ||
194 | if (who) | |
195 | free_uid(user); | |
196 | break; | |
197 | default: | |
198 | ret = -EINVAL; | |
199 | } | |
200 | ||
201 | read_unlock_irq(&tasklist_lock); | |
202 | return ret; | |
203 | } | |
204 |