blob: f84b380d65e5d1a1898248bdb7a77dd3bc8b5aa4 [file] [log] [blame]
Jens Axboe22e2c502005-06-27 10:55:12 +02001/*
2 * fs/ioprio.c
3 *
Jens Axboe0fe23472006-09-04 15:41:16 +02004 * Copyright (C) 2004 Jens Axboe <axboe@kernel.dk>
Jens Axboe22e2c502005-06-27 10:55:12 +02005 *
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 */
Tejun Heo5a0e3ad2010-03-24 17:04:11 +090022#include <linux/gfp.h>
Jens Axboe22e2c502005-06-27 10:55:12 +020023#include <linux/kernel.h>
Paul Gortmakerafeacc82011-05-26 16:00:52 -040024#include <linux/export.h>
Jens Axboe22e2c502005-06-27 10:55:12 +020025#include <linux/ioprio.h>
26#include <linux/blkdev.h>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080027#include <linux/capability.h>
Adrian Bunk9abdc4c2005-11-08 16:57:02 +010028#include <linux/syscalls.h>
James Morris03e68062006-06-23 02:03:58 -070029#include <linux/security.h>
Pavel Emelyanovb4888932007-10-18 23:40:14 -070030#include <linux/pid_namespace.h>
Jens Axboe22e2c502005-06-27 10:55:12 +020031
Theodore Ts'ob3881f72009-01-05 22:46:26 -050032int set_task_ioprio(struct task_struct *task, int ioprio)
Jens Axboe22e2c502005-06-27 10:55:12 +020033{
James Morris03e68062006-06-23 02:03:58 -070034 int err;
Jens Axboe22e2c502005-06-27 10:55:12 +020035 struct io_context *ioc;
David Howellsc69e8d92008-11-14 10:39:19 +110036 const struct cred *cred = current_cred(), *tcred;
Jens Axboe22e2c502005-06-27 10:55:12 +020037
David Howellsc69e8d92008-11-14 10:39:19 +110038 rcu_read_lock();
39 tcred = __task_cred(task);
40 if (tcred->uid != cred->euid &&
41 tcred->uid != cred->uid && !capable(CAP_SYS_NICE)) {
42 rcu_read_unlock();
Jens Axboe22e2c502005-06-27 10:55:12 +020043 return -EPERM;
David Howellsc69e8d92008-11-14 10:39:19 +110044 }
45 rcu_read_unlock();
Jens Axboe22e2c502005-06-27 10:55:12 +020046
James Morris03e68062006-06-23 02:03:58 -070047 err = security_task_setioprio(task, ioprio);
48 if (err)
49 return err;
50
Tejun Heo6e736be2011-12-14 00:33:38 +010051 ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE);
52 if (ioc) {
Tejun Heodc869002011-12-14 00:33:38 +010053 ioc_ioprio_changed(ioc, ioprio);
Tejun Heob2efa052011-12-14 00:33:39 +010054 put_io_context(ioc, NULL);
Jens Axboefd0928d2008-01-24 08:52:45 +010055 }
Jens Axboe22e2c502005-06-27 10:55:12 +020056
Jens Axboefd0928d2008-01-24 08:52:45 +010057 return err;
Jens Axboe22e2c502005-06-27 10:55:12 +020058}
Theodore Ts'ob3881f72009-01-05 22:46:26 -050059EXPORT_SYMBOL_GPL(set_task_ioprio);
Jens Axboe22e2c502005-06-27 10:55:12 +020060
Heiko Carstens938bb9f2009-01-14 14:14:30 +010061SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio)
Jens Axboe22e2c502005-06-27 10:55:12 +020062{
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;
Eric W. Biederman41487c62007-02-12 00:53:01 -080067 struct pid *pgrp;
Jens Axboe22e2c502005-06-27 10:55:12 +020068 int ret;
69
70 switch (class) {
71 case IOPRIO_CLASS_RT:
72 if (!capable(CAP_SYS_ADMIN))
73 return -EPERM;
74 /* fall through, rt has prio field too */
75 case IOPRIO_CLASS_BE:
76 if (data >= IOPRIO_BE_NR || data < 0)
77 return -EINVAL;
78
79 break;
80 case IOPRIO_CLASS_IDLE:
81 break;
Jens Axboe8ec680e2007-11-07 13:54:07 +010082 case IOPRIO_CLASS_NONE:
83 if (data)
84 return -EINVAL;
85 break;
Jens Axboe22e2c502005-06-27 10:55:12 +020086 default:
87 return -EINVAL;
88 }
89
90 ret = -ESRCH;
Greg Thelend69b78b2010-11-15 10:20:52 +010091 rcu_read_lock();
Jens Axboe22e2c502005-06-27 10:55:12 +020092 switch (which) {
93 case IOPRIO_WHO_PROCESS:
94 if (!who)
95 p = current;
96 else
Pavel Emelyanov228ebcb2007-10-18 23:40:16 -070097 p = find_task_by_vpid(who);
Jens Axboe22e2c502005-06-27 10:55:12 +020098 if (p)
99 ret = set_task_ioprio(p, ioprio);
100 break;
101 case IOPRIO_WHO_PGRP:
102 if (!who)
Eric W. Biederman41487c62007-02-12 00:53:01 -0800103 pgrp = task_pgrp(current);
104 else
Pavel Emelyanovb4888932007-10-18 23:40:14 -0700105 pgrp = find_vpid(who);
Ken Chen2d70b682008-08-20 14:09:17 -0700106 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
Jens Axboe22e2c502005-06-27 10:55:12 +0200107 ret = set_task_ioprio(p, ioprio);
108 if (ret)
109 break;
Ken Chen2d70b682008-08-20 14:09:17 -0700110 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
Jens Axboe22e2c502005-06-27 10:55:12 +0200111 break;
112 case IOPRIO_WHO_USER:
113 if (!who)
David Howells86a264a2008-11-14 10:39:18 +1100114 user = current_user();
Jens Axboe22e2c502005-06-27 10:55:12 +0200115 else
116 user = find_user(who);
117
118 if (!user)
119 break;
120
121 do_each_thread(g, p) {
Greg Thelend69b78b2010-11-15 10:20:52 +0100122 if (__task_cred(p)->uid != who)
Jens Axboe22e2c502005-06-27 10:55:12 +0200123 continue;
124 ret = set_task_ioprio(p, ioprio);
125 if (ret)
Oleg Nesterov78bd4d42006-08-21 08:33:23 +0200126 goto free_uid;
Jens Axboe22e2c502005-06-27 10:55:12 +0200127 } while_each_thread(g, p);
Oleg Nesterov78bd4d42006-08-21 08:33:23 +0200128free_uid:
Jens Axboe22e2c502005-06-27 10:55:12 +0200129 if (who)
130 free_uid(user);
131 break;
132 default:
133 ret = -EINVAL;
134 }
135
Greg Thelend69b78b2010-11-15 10:20:52 +0100136 rcu_read_unlock();
Jens Axboe22e2c502005-06-27 10:55:12 +0200137 return ret;
138}
139
David Quigleya1836a42006-06-30 01:55:49 -0700140static int get_task_ioprio(struct task_struct *p)
141{
142 int ret;
143
144 ret = security_task_getioprio(p);
145 if (ret)
146 goto out;
Jens Axboefd0928d2008-01-24 08:52:45 +0100147 ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM);
148 if (p->io_context)
149 ret = p->io_context->ioprio;
David Quigleya1836a42006-06-30 01:55:49 -0700150out:
151 return ret;
152}
153
Oleg Nesterove014ff82006-08-21 10:02:50 +0200154int ioprio_best(unsigned short aprio, unsigned short bprio)
155{
156 unsigned short aclass = IOPRIO_PRIO_CLASS(aprio);
157 unsigned short bclass = IOPRIO_PRIO_CLASS(bprio);
158
Oleg Nesterove014ff82006-08-21 10:02:50 +0200159 if (aclass == IOPRIO_CLASS_NONE)
160 aclass = IOPRIO_CLASS_BE;
161 if (bclass == IOPRIO_CLASS_NONE)
162 bclass = IOPRIO_CLASS_BE;
163
164 if (aclass == bclass)
165 return min(aprio, bprio);
166 if (aclass > bclass)
167 return bprio;
168 else
169 return aprio;
170}
171
Heiko Carstens938bb9f2009-01-14 14:14:30 +0100172SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
Jens Axboe22e2c502005-06-27 10:55:12 +0200173{
174 struct task_struct *g, *p;
175 struct user_struct *user;
Eric W. Biederman41487c62007-02-12 00:53:01 -0800176 struct pid *pgrp;
Jens Axboe22e2c502005-06-27 10:55:12 +0200177 int ret = -ESRCH;
David Quigleya1836a42006-06-30 01:55:49 -0700178 int tmpio;
Jens Axboe22e2c502005-06-27 10:55:12 +0200179
Greg Thelend69b78b2010-11-15 10:20:52 +0100180 rcu_read_lock();
Jens Axboe22e2c502005-06-27 10:55:12 +0200181 switch (which) {
182 case IOPRIO_WHO_PROCESS:
183 if (!who)
184 p = current;
185 else
Pavel Emelyanov228ebcb2007-10-18 23:40:16 -0700186 p = find_task_by_vpid(who);
Jens Axboe22e2c502005-06-27 10:55:12 +0200187 if (p)
David Quigleya1836a42006-06-30 01:55:49 -0700188 ret = get_task_ioprio(p);
Jens Axboe22e2c502005-06-27 10:55:12 +0200189 break;
190 case IOPRIO_WHO_PGRP:
191 if (!who)
Eric W. Biederman41487c62007-02-12 00:53:01 -0800192 pgrp = task_pgrp(current);
193 else
Pavel Emelyanovb4888932007-10-18 23:40:14 -0700194 pgrp = find_vpid(who);
Ken Chen2d70b682008-08-20 14:09:17 -0700195 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
David Quigleya1836a42006-06-30 01:55:49 -0700196 tmpio = get_task_ioprio(p);
197 if (tmpio < 0)
198 continue;
Jens Axboe22e2c502005-06-27 10:55:12 +0200199 if (ret == -ESRCH)
David Quigleya1836a42006-06-30 01:55:49 -0700200 ret = tmpio;
Jens Axboe22e2c502005-06-27 10:55:12 +0200201 else
David Quigleya1836a42006-06-30 01:55:49 -0700202 ret = ioprio_best(ret, tmpio);
Ken Chen2d70b682008-08-20 14:09:17 -0700203 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
Jens Axboe22e2c502005-06-27 10:55:12 +0200204 break;
205 case IOPRIO_WHO_USER:
206 if (!who)
David Howells86a264a2008-11-14 10:39:18 +1100207 user = current_user();
Jens Axboe22e2c502005-06-27 10:55:12 +0200208 else
209 user = find_user(who);
210
211 if (!user)
212 break;
213
214 do_each_thread(g, p) {
Greg Thelend69b78b2010-11-15 10:20:52 +0100215 if (__task_cred(p)->uid != user->uid)
Jens Axboe22e2c502005-06-27 10:55:12 +0200216 continue;
David Quigleya1836a42006-06-30 01:55:49 -0700217 tmpio = get_task_ioprio(p);
218 if (tmpio < 0)
219 continue;
Jens Axboe22e2c502005-06-27 10:55:12 +0200220 if (ret == -ESRCH)
David Quigleya1836a42006-06-30 01:55:49 -0700221 ret = tmpio;
Jens Axboe22e2c502005-06-27 10:55:12 +0200222 else
David Quigleya1836a42006-06-30 01:55:49 -0700223 ret = ioprio_best(ret, tmpio);
Jens Axboe22e2c502005-06-27 10:55:12 +0200224 } while_each_thread(g, p);
225
226 if (who)
227 free_uid(user);
228 break;
229 default:
230 ret = -EINVAL;
231 }
232
Greg Thelend69b78b2010-11-15 10:20:52 +0100233 rcu_read_unlock();
Jens Axboe22e2c502005-06-27 10:55:12 +0200234 return ret;
235}