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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> | |
9abdc4cd | 25 | #include <linux/syscalls.h> |
22e2c507 JA |
26 | |
27 | static int set_task_ioprio(struct task_struct *task, int ioprio) | |
28 | { | |
29 | struct io_context *ioc; | |
30 | ||
31 | if (task->uid != current->euid && | |
32 | task->uid != current->uid && !capable(CAP_SYS_NICE)) | |
33 | return -EPERM; | |
34 | ||
35 | task_lock(task); | |
36 | ||
37 | task->ioprio = ioprio; | |
38 | ||
39 | ioc = task->io_context; | |
40 | if (ioc && ioc->set_ioprio) | |
41 | ioc->set_ioprio(ioc, ioprio); | |
42 | ||
43 | task_unlock(task); | |
44 | return 0; | |
45 | } | |
46 | ||
cf366808 | 47 | asmlinkage long sys_ioprio_set(int which, int who, int ioprio) |
22e2c507 JA |
48 | { |
49 | int class = IOPRIO_PRIO_CLASS(ioprio); | |
50 | int data = IOPRIO_PRIO_DATA(ioprio); | |
51 | struct task_struct *p, *g; | |
52 | struct user_struct *user; | |
53 | int ret; | |
54 | ||
55 | switch (class) { | |
56 | case IOPRIO_CLASS_RT: | |
57 | if (!capable(CAP_SYS_ADMIN)) | |
58 | return -EPERM; | |
59 | /* fall through, rt has prio field too */ | |
60 | case IOPRIO_CLASS_BE: | |
61 | if (data >= IOPRIO_BE_NR || data < 0) | |
62 | return -EINVAL; | |
63 | ||
64 | break; | |
65 | case IOPRIO_CLASS_IDLE: | |
f6fdd7d9 LT |
66 | if (!capable(CAP_SYS_ADMIN)) |
67 | return -EPERM; | |
22e2c507 JA |
68 | break; |
69 | default: | |
70 | return -EINVAL; | |
71 | } | |
72 | ||
73 | ret = -ESRCH; | |
74 | read_lock_irq(&tasklist_lock); | |
75 | switch (which) { | |
76 | case IOPRIO_WHO_PROCESS: | |
77 | if (!who) | |
78 | p = current; | |
79 | else | |
80 | p = find_task_by_pid(who); | |
81 | if (p) | |
82 | ret = set_task_ioprio(p, ioprio); | |
83 | break; | |
84 | case IOPRIO_WHO_PGRP: | |
85 | if (!who) | |
86 | who = process_group(current); | |
87 | do_each_task_pid(who, PIDTYPE_PGID, p) { | |
88 | ret = set_task_ioprio(p, ioprio); | |
89 | if (ret) | |
90 | break; | |
91 | } while_each_task_pid(who, PIDTYPE_PGID, p); | |
92 | break; | |
93 | case IOPRIO_WHO_USER: | |
94 | if (!who) | |
95 | user = current->user; | |
96 | else | |
97 | user = find_user(who); | |
98 | ||
99 | if (!user) | |
100 | break; | |
101 | ||
102 | do_each_thread(g, p) { | |
103 | if (p->uid != who) | |
104 | continue; | |
105 | ret = set_task_ioprio(p, ioprio); | |
106 | if (ret) | |
107 | break; | |
108 | } while_each_thread(g, p); | |
109 | ||
110 | if (who) | |
111 | free_uid(user); | |
112 | break; | |
113 | default: | |
114 | ret = -EINVAL; | |
115 | } | |
116 | ||
117 | read_unlock_irq(&tasklist_lock); | |
118 | return ret; | |
119 | } | |
120 | ||
cf366808 | 121 | asmlinkage long sys_ioprio_get(int which, int who) |
22e2c507 JA |
122 | { |
123 | struct task_struct *g, *p; | |
124 | struct user_struct *user; | |
125 | int ret = -ESRCH; | |
126 | ||
127 | read_lock_irq(&tasklist_lock); | |
128 | switch (which) { | |
129 | case IOPRIO_WHO_PROCESS: | |
130 | if (!who) | |
131 | p = current; | |
132 | else | |
133 | p = find_task_by_pid(who); | |
134 | if (p) | |
135 | ret = p->ioprio; | |
136 | break; | |
137 | case IOPRIO_WHO_PGRP: | |
138 | if (!who) | |
139 | who = process_group(current); | |
140 | do_each_task_pid(who, PIDTYPE_PGID, p) { | |
141 | if (ret == -ESRCH) | |
142 | ret = p->ioprio; | |
143 | else | |
144 | ret = ioprio_best(ret, p->ioprio); | |
145 | } while_each_task_pid(who, PIDTYPE_PGID, p); | |
146 | break; | |
147 | case IOPRIO_WHO_USER: | |
148 | if (!who) | |
149 | user = current->user; | |
150 | else | |
151 | user = find_user(who); | |
152 | ||
153 | if (!user) | |
154 | break; | |
155 | ||
156 | do_each_thread(g, p) { | |
157 | if (p->uid != user->uid) | |
158 | continue; | |
159 | if (ret == -ESRCH) | |
160 | ret = p->ioprio; | |
161 | else | |
162 | ret = ioprio_best(ret, p->ioprio); | |
163 | } while_each_thread(g, p); | |
164 | ||
165 | if (who) | |
166 | free_uid(user); | |
167 | break; | |
168 | default: | |
169 | ret = -EINVAL; | |
170 | } | |
171 | ||
172 | read_unlock_irq(&tasklist_lock); | |
173 | return ret; | |
174 | } | |
175 |