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