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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);
Eric W. Biederman8e96e3b2012-03-03 21:17:15 -080040 if (!uid_eq(tcred->uid, cred->euid) &&
41 !uid_eq(tcred->uid, cred->uid) && !capable(CAP_SYS_NICE)) {
David Howellsc69e8d92008-11-14 10:39:19 +110042 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 Heo2b566fa2012-03-19 15:10:59 -070053 ioc->ioprio = ioprio;
Tejun Heo11a31222012-02-07 07:51:30 +010054 put_io_context(ioc);
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;
Eric W. Biederman7b44ab92011-11-16 23:20:58 -080068 kuid_t uid;
Jens Axboe22e2c502005-06-27 10:55:12 +020069 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;
Jens Axboe8ec680e2007-11-07 13:54:07 +010083 case IOPRIO_CLASS_NONE:
84 if (data)
85 return -EINVAL;
86 break;
Jens Axboe22e2c502005-06-27 10:55:12 +020087 default:
88 return -EINVAL;
89 }
90
91 ret = -ESRCH;
Greg Thelend69b78b2010-11-15 10:20:52 +010092 rcu_read_lock();
Jens Axboe22e2c502005-06-27 10:55:12 +020093 switch (which) {
94 case IOPRIO_WHO_PROCESS:
95 if (!who)
96 p = current;
97 else
Pavel Emelyanov228ebcb2007-10-18 23:40:16 -070098 p = find_task_by_vpid(who);
Jens Axboe22e2c502005-06-27 10:55:12 +020099 if (p)
100 ret = set_task_ioprio(p, ioprio);
101 break;
102 case IOPRIO_WHO_PGRP:
103 if (!who)
Eric W. Biederman41487c62007-02-12 00:53:01 -0800104 pgrp = task_pgrp(current);
105 else
Pavel Emelyanovb4888932007-10-18 23:40:14 -0700106 pgrp = find_vpid(who);
Ken Chen2d70b682008-08-20 14:09:17 -0700107 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
Jens Axboe22e2c502005-06-27 10:55:12 +0200108 ret = set_task_ioprio(p, ioprio);
109 if (ret)
110 break;
Ken Chen2d70b682008-08-20 14:09:17 -0700111 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
Jens Axboe22e2c502005-06-27 10:55:12 +0200112 break;
113 case IOPRIO_WHO_USER:
Eric W. Biederman7b44ab92011-11-16 23:20:58 -0800114 uid = make_kuid(current_user_ns(), who);
115 if (!uid_valid(uid))
116 break;
Jens Axboe22e2c502005-06-27 10:55:12 +0200117 if (!who)
David Howells86a264a2008-11-14 10:39:18 +1100118 user = current_user();
Jens Axboe22e2c502005-06-27 10:55:12 +0200119 else
Eric W. Biederman7b44ab92011-11-16 23:20:58 -0800120 user = find_user(uid);
Jens Axboe22e2c502005-06-27 10:55:12 +0200121
122 if (!user)
123 break;
124
125 do_each_thread(g, p) {
Eric W. Biederman078de5f2012-02-08 07:00:08 -0800126 if (!uid_eq(task_uid(p), uid))
Jens Axboe22e2c502005-06-27 10:55:12 +0200127 continue;
128 ret = set_task_ioprio(p, ioprio);
129 if (ret)
Oleg Nesterov78bd4d42006-08-21 08:33:23 +0200130 goto free_uid;
Jens Axboe22e2c502005-06-27 10:55:12 +0200131 } while_each_thread(g, p);
Oleg Nesterov78bd4d42006-08-21 08:33:23 +0200132free_uid:
Jens Axboe22e2c502005-06-27 10:55:12 +0200133 if (who)
134 free_uid(user);
135 break;
136 default:
137 ret = -EINVAL;
138 }
139
Greg Thelend69b78b2010-11-15 10:20:52 +0100140 rcu_read_unlock();
Jens Axboe22e2c502005-06-27 10:55:12 +0200141 return ret;
142}
143
David Quigleya1836a42006-06-30 01:55:49 -0700144static int get_task_ioprio(struct task_struct *p)
145{
146 int ret;
147
148 ret = security_task_getioprio(p);
149 if (ret)
150 goto out;
Jens Axboefd0928d2008-01-24 08:52:45 +0100151 ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM);
152 if (p->io_context)
153 ret = p->io_context->ioprio;
David Quigleya1836a42006-06-30 01:55:49 -0700154out:
155 return ret;
156}
157
Oleg Nesterove014ff82006-08-21 10:02:50 +0200158int ioprio_best(unsigned short aprio, unsigned short bprio)
159{
160 unsigned short aclass = IOPRIO_PRIO_CLASS(aprio);
161 unsigned short bclass = IOPRIO_PRIO_CLASS(bprio);
162
Oleg Nesterove014ff82006-08-21 10:02:50 +0200163 if (aclass == IOPRIO_CLASS_NONE)
164 aclass = IOPRIO_CLASS_BE;
165 if (bclass == IOPRIO_CLASS_NONE)
166 bclass = IOPRIO_CLASS_BE;
167
168 if (aclass == bclass)
169 return min(aprio, bprio);
170 if (aclass > bclass)
171 return bprio;
172 else
173 return aprio;
174}
175
Heiko Carstens938bb9f2009-01-14 14:14:30 +0100176SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
Jens Axboe22e2c502005-06-27 10:55:12 +0200177{
178 struct task_struct *g, *p;
179 struct user_struct *user;
Eric W. Biederman41487c62007-02-12 00:53:01 -0800180 struct pid *pgrp;
Eric W. Biederman7b44ab92011-11-16 23:20:58 -0800181 kuid_t uid;
Jens Axboe22e2c502005-06-27 10:55:12 +0200182 int ret = -ESRCH;
David Quigleya1836a42006-06-30 01:55:49 -0700183 int tmpio;
Jens Axboe22e2c502005-06-27 10:55:12 +0200184
Greg Thelend69b78b2010-11-15 10:20:52 +0100185 rcu_read_lock();
Jens Axboe22e2c502005-06-27 10:55:12 +0200186 switch (which) {
187 case IOPRIO_WHO_PROCESS:
188 if (!who)
189 p = current;
190 else
Pavel Emelyanov228ebcb2007-10-18 23:40:16 -0700191 p = find_task_by_vpid(who);
Jens Axboe22e2c502005-06-27 10:55:12 +0200192 if (p)
David Quigleya1836a42006-06-30 01:55:49 -0700193 ret = get_task_ioprio(p);
Jens Axboe22e2c502005-06-27 10:55:12 +0200194 break;
195 case IOPRIO_WHO_PGRP:
196 if (!who)
Eric W. Biederman41487c62007-02-12 00:53:01 -0800197 pgrp = task_pgrp(current);
198 else
Pavel Emelyanovb4888932007-10-18 23:40:14 -0700199 pgrp = find_vpid(who);
Ken Chen2d70b682008-08-20 14:09:17 -0700200 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
David Quigleya1836a42006-06-30 01:55:49 -0700201 tmpio = get_task_ioprio(p);
202 if (tmpio < 0)
203 continue;
Jens Axboe22e2c502005-06-27 10:55:12 +0200204 if (ret == -ESRCH)
David Quigleya1836a42006-06-30 01:55:49 -0700205 ret = tmpio;
Jens Axboe22e2c502005-06-27 10:55:12 +0200206 else
David Quigleya1836a42006-06-30 01:55:49 -0700207 ret = ioprio_best(ret, tmpio);
Ken Chen2d70b682008-08-20 14:09:17 -0700208 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
Jens Axboe22e2c502005-06-27 10:55:12 +0200209 break;
210 case IOPRIO_WHO_USER:
Eric W. Biederman7b44ab92011-11-16 23:20:58 -0800211 uid = make_kuid(current_user_ns(), who);
Jens Axboe22e2c502005-06-27 10:55:12 +0200212 if (!who)
David Howells86a264a2008-11-14 10:39:18 +1100213 user = current_user();
Jens Axboe22e2c502005-06-27 10:55:12 +0200214 else
Eric W. Biederman7b44ab92011-11-16 23:20:58 -0800215 user = find_user(uid);
Jens Axboe22e2c502005-06-27 10:55:12 +0200216
217 if (!user)
218 break;
219
220 do_each_thread(g, p) {
Eric W. Biederman078de5f2012-02-08 07:00:08 -0800221 if (!uid_eq(task_uid(p), user->uid))
Jens Axboe22e2c502005-06-27 10:55:12 +0200222 continue;
David Quigleya1836a42006-06-30 01:55:49 -0700223 tmpio = get_task_ioprio(p);
224 if (tmpio < 0)
225 continue;
Jens Axboe22e2c502005-06-27 10:55:12 +0200226 if (ret == -ESRCH)
David Quigleya1836a42006-06-30 01:55:49 -0700227 ret = tmpio;
Jens Axboe22e2c502005-06-27 10:55:12 +0200228 else
David Quigleya1836a42006-06-30 01:55:49 -0700229 ret = ioprio_best(ret, tmpio);
Jens Axboe22e2c502005-06-27 10:55:12 +0200230 } while_each_thread(g, p);
231
232 if (who)
233 free_uid(user);
234 break;
235 default:
236 ret = -EINVAL;
237 }
238
Greg Thelend69b78b2010-11-15 10:20:52 +0100239 rcu_read_unlock();
Jens Axboe22e2c502005-06-27 10:55:12 +0200240 return ret;
241}