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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>
Ingo Molnar5b825c32017-02-02 17:54:15 +010026#include <linux/cred.h>
Jens Axboe22e2c502005-06-27 10:55:12 +020027#include <linux/blkdev.h>
Randy Dunlap16f7e0f2006-01-11 12:17:46 -080028#include <linux/capability.h>
Ingo Molnar8703e8a2017-02-08 18:51:30 +010029#include <linux/sched/user.h>
Ingo Molnarf719ff92017-02-06 10:57:33 +010030#include <linux/sched/task.h>
Adrian Bunk9abdc4c2005-11-08 16:57:02 +010031#include <linux/syscalls.h>
James Morris03e68062006-06-23 02:03:58 -070032#include <linux/security.h>
Pavel Emelyanovb4888932007-10-18 23:40:14 -070033#include <linux/pid_namespace.h>
Jens Axboe22e2c502005-06-27 10:55:12 +020034
Theodore Ts'ob3881f72009-01-05 22:46:26 -050035int set_task_ioprio(struct task_struct *task, int ioprio)
Jens Axboe22e2c502005-06-27 10:55:12 +020036{
James Morris03e68062006-06-23 02:03:58 -070037 int err;
Jens Axboe22e2c502005-06-27 10:55:12 +020038 struct io_context *ioc;
David Howellsc69e8d92008-11-14 10:39:19 +110039 const struct cred *cred = current_cred(), *tcred;
Jens Axboe22e2c502005-06-27 10:55:12 +020040
David Howellsc69e8d92008-11-14 10:39:19 +110041 rcu_read_lock();
42 tcred = __task_cred(task);
Eric W. Biederman8e96e3b2012-03-03 21:17:15 -080043 if (!uid_eq(tcred->uid, cred->euid) &&
44 !uid_eq(tcred->uid, cred->uid) && !capable(CAP_SYS_NICE)) {
David Howellsc69e8d92008-11-14 10:39:19 +110045 rcu_read_unlock();
Jens Axboe22e2c502005-06-27 10:55:12 +020046 return -EPERM;
David Howellsc69e8d92008-11-14 10:39:19 +110047 }
48 rcu_read_unlock();
Jens Axboe22e2c502005-06-27 10:55:12 +020049
James Morris03e68062006-06-23 02:03:58 -070050 err = security_task_setioprio(task, ioprio);
51 if (err)
52 return err;
53
Tejun Heo6e736be2011-12-14 00:33:38 +010054 ioc = get_task_io_context(task, GFP_ATOMIC, NUMA_NO_NODE);
55 if (ioc) {
Tejun Heo2b566fa2012-03-19 15:10:59 -070056 ioc->ioprio = ioprio;
Tejun Heo11a31222012-02-07 07:51:30 +010057 put_io_context(ioc);
Jens Axboefd0928d2008-01-24 08:52:45 +010058 }
Jens Axboe22e2c502005-06-27 10:55:12 +020059
Jens Axboefd0928d2008-01-24 08:52:45 +010060 return err;
Jens Axboe22e2c502005-06-27 10:55:12 +020061}
Theodore Ts'ob3881f72009-01-05 22:46:26 -050062EXPORT_SYMBOL_GPL(set_task_ioprio);
Jens Axboe22e2c502005-06-27 10:55:12 +020063
Heiko Carstens938bb9f2009-01-14 14:14:30 +010064SYSCALL_DEFINE3(ioprio_set, int, which, int, who, int, ioprio)
Jens Axboe22e2c502005-06-27 10:55:12 +020065{
66 int class = IOPRIO_PRIO_CLASS(ioprio);
67 int data = IOPRIO_PRIO_DATA(ioprio);
68 struct task_struct *p, *g;
69 struct user_struct *user;
Eric W. Biederman41487c62007-02-12 00:53:01 -080070 struct pid *pgrp;
Eric W. Biederman7b44ab92011-11-16 23:20:58 -080071 kuid_t uid;
Jens Axboe22e2c502005-06-27 10:55:12 +020072 int ret;
73
74 switch (class) {
75 case IOPRIO_CLASS_RT:
76 if (!capable(CAP_SYS_ADMIN))
77 return -EPERM;
78 /* fall through, rt has prio field too */
79 case IOPRIO_CLASS_BE:
80 if (data >= IOPRIO_BE_NR || data < 0)
81 return -EINVAL;
82
83 break;
84 case IOPRIO_CLASS_IDLE:
85 break;
Jens Axboe8ec680e2007-11-07 13:54:07 +010086 case IOPRIO_CLASS_NONE:
87 if (data)
88 return -EINVAL;
89 break;
Jens Axboe22e2c502005-06-27 10:55:12 +020090 default:
91 return -EINVAL;
92 }
93
94 ret = -ESRCH;
Greg Thelend69b78b2010-11-15 10:20:52 +010095 rcu_read_lock();
Jens Axboe22e2c502005-06-27 10:55:12 +020096 switch (which) {
97 case IOPRIO_WHO_PROCESS:
98 if (!who)
99 p = current;
100 else
Pavel Emelyanov228ebcb2007-10-18 23:40:16 -0700101 p = find_task_by_vpid(who);
Jens Axboe22e2c502005-06-27 10:55:12 +0200102 if (p)
103 ret = set_task_ioprio(p, ioprio);
104 break;
105 case IOPRIO_WHO_PGRP:
106 if (!who)
Eric W. Biederman41487c62007-02-12 00:53:01 -0800107 pgrp = task_pgrp(current);
108 else
Pavel Emelyanovb4888932007-10-18 23:40:14 -0700109 pgrp = find_vpid(who);
Ken Chen2d70b682008-08-20 14:09:17 -0700110 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
Jens Axboe22e2c502005-06-27 10:55:12 +0200111 ret = set_task_ioprio(p, ioprio);
112 if (ret)
113 break;
Ken Chen2d70b682008-08-20 14:09:17 -0700114 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
Jens Axboe22e2c502005-06-27 10:55:12 +0200115 break;
116 case IOPRIO_WHO_USER:
Eric W. Biederman7b44ab92011-11-16 23:20:58 -0800117 uid = make_kuid(current_user_ns(), who);
118 if (!uid_valid(uid))
119 break;
Jens Axboe22e2c502005-06-27 10:55:12 +0200120 if (!who)
David Howells86a264a2008-11-14 10:39:18 +1100121 user = current_user();
Jens Axboe22e2c502005-06-27 10:55:12 +0200122 else
Eric W. Biederman7b44ab92011-11-16 23:20:58 -0800123 user = find_user(uid);
Jens Axboe22e2c502005-06-27 10:55:12 +0200124
125 if (!user)
126 break;
127
Tetsuo Handa612dafa2017-02-22 15:40:50 -0800128 for_each_process_thread(g, p) {
Ben Segall8639b462015-11-06 16:32:48 -0800129 if (!uid_eq(task_uid(p), uid) ||
130 !task_pid_vnr(p))
Jens Axboe22e2c502005-06-27 10:55:12 +0200131 continue;
132 ret = set_task_ioprio(p, ioprio);
133 if (ret)
Oleg Nesterov78bd4d42006-08-21 08:33:23 +0200134 goto free_uid;
Tetsuo Handa612dafa2017-02-22 15:40:50 -0800135 }
Oleg Nesterov78bd4d42006-08-21 08:33:23 +0200136free_uid:
Jens Axboe22e2c502005-06-27 10:55:12 +0200137 if (who)
138 free_uid(user);
139 break;
140 default:
141 ret = -EINVAL;
142 }
143
Greg Thelend69b78b2010-11-15 10:20:52 +0100144 rcu_read_unlock();
Jens Axboe22e2c502005-06-27 10:55:12 +0200145 return ret;
146}
147
David Quigleya1836a42006-06-30 01:55:49 -0700148static int get_task_ioprio(struct task_struct *p)
149{
150 int ret;
151
152 ret = security_task_getioprio(p);
153 if (ret)
154 goto out;
Jens Axboefd0928d2008-01-24 08:52:45 +0100155 ret = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_NONE, IOPRIO_NORM);
Omar Sandoval8ba86822016-07-01 00:39:35 -0700156 task_lock(p);
Jens Axboefd0928d2008-01-24 08:52:45 +0100157 if (p->io_context)
158 ret = p->io_context->ioprio;
Omar Sandoval8ba86822016-07-01 00:39:35 -0700159 task_unlock(p);
David Quigleya1836a42006-06-30 01:55:49 -0700160out:
161 return ret;
162}
163
Oleg Nesterove014ff82006-08-21 10:02:50 +0200164int ioprio_best(unsigned short aprio, unsigned short bprio)
165{
Jan Karaece9c722014-10-30 20:43:38 +0100166 if (!ioprio_valid(aprio))
167 aprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
168 if (!ioprio_valid(bprio))
169 bprio = IOPRIO_PRIO_VALUE(IOPRIO_CLASS_BE, IOPRIO_NORM);
Oleg Nesterove014ff82006-08-21 10:02:50 +0200170
Bart Van Assche9a871822017-04-19 14:01:28 -0700171 return min(aprio, bprio);
Oleg Nesterove014ff82006-08-21 10:02:50 +0200172}
173
Heiko Carstens938bb9f2009-01-14 14:14:30 +0100174SYSCALL_DEFINE2(ioprio_get, int, which, int, who)
Jens Axboe22e2c502005-06-27 10:55:12 +0200175{
176 struct task_struct *g, *p;
177 struct user_struct *user;
Eric W. Biederman41487c62007-02-12 00:53:01 -0800178 struct pid *pgrp;
Eric W. Biederman7b44ab92011-11-16 23:20:58 -0800179 kuid_t uid;
Jens Axboe22e2c502005-06-27 10:55:12 +0200180 int ret = -ESRCH;
David Quigleya1836a42006-06-30 01:55:49 -0700181 int tmpio;
Jens Axboe22e2c502005-06-27 10:55:12 +0200182
Greg Thelend69b78b2010-11-15 10:20:52 +0100183 rcu_read_lock();
Jens Axboe22e2c502005-06-27 10:55:12 +0200184 switch (which) {
185 case IOPRIO_WHO_PROCESS:
186 if (!who)
187 p = current;
188 else
Pavel Emelyanov228ebcb2007-10-18 23:40:16 -0700189 p = find_task_by_vpid(who);
Jens Axboe22e2c502005-06-27 10:55:12 +0200190 if (p)
David Quigleya1836a42006-06-30 01:55:49 -0700191 ret = get_task_ioprio(p);
Jens Axboe22e2c502005-06-27 10:55:12 +0200192 break;
193 case IOPRIO_WHO_PGRP:
194 if (!who)
Eric W. Biederman41487c62007-02-12 00:53:01 -0800195 pgrp = task_pgrp(current);
196 else
Pavel Emelyanovb4888932007-10-18 23:40:14 -0700197 pgrp = find_vpid(who);
Ken Chen2d70b682008-08-20 14:09:17 -0700198 do_each_pid_thread(pgrp, PIDTYPE_PGID, p) {
David Quigleya1836a42006-06-30 01:55:49 -0700199 tmpio = get_task_ioprio(p);
200 if (tmpio < 0)
201 continue;
Jens Axboe22e2c502005-06-27 10:55:12 +0200202 if (ret == -ESRCH)
David Quigleya1836a42006-06-30 01:55:49 -0700203 ret = tmpio;
Jens Axboe22e2c502005-06-27 10:55:12 +0200204 else
David Quigleya1836a42006-06-30 01:55:49 -0700205 ret = ioprio_best(ret, tmpio);
Ken Chen2d70b682008-08-20 14:09:17 -0700206 } while_each_pid_thread(pgrp, PIDTYPE_PGID, p);
Jens Axboe22e2c502005-06-27 10:55:12 +0200207 break;
208 case IOPRIO_WHO_USER:
Eric W. Biederman7b44ab92011-11-16 23:20:58 -0800209 uid = make_kuid(current_user_ns(), who);
Jens Axboe22e2c502005-06-27 10:55:12 +0200210 if (!who)
David Howells86a264a2008-11-14 10:39:18 +1100211 user = current_user();
Jens Axboe22e2c502005-06-27 10:55:12 +0200212 else
Eric W. Biederman7b44ab92011-11-16 23:20:58 -0800213 user = find_user(uid);
Jens Axboe22e2c502005-06-27 10:55:12 +0200214
215 if (!user)
216 break;
217
Tetsuo Handa612dafa2017-02-22 15:40:50 -0800218 for_each_process_thread(g, p) {
Ben Segall8639b462015-11-06 16:32:48 -0800219 if (!uid_eq(task_uid(p), user->uid) ||
220 !task_pid_vnr(p))
Jens Axboe22e2c502005-06-27 10:55:12 +0200221 continue;
David Quigleya1836a42006-06-30 01:55:49 -0700222 tmpio = get_task_ioprio(p);
223 if (tmpio < 0)
224 continue;
Jens Axboe22e2c502005-06-27 10:55:12 +0200225 if (ret == -ESRCH)
David Quigleya1836a42006-06-30 01:55:49 -0700226 ret = tmpio;
Jens Axboe22e2c502005-06-27 10:55:12 +0200227 else
David Quigleya1836a42006-06-30 01:55:49 -0700228 ret = ioprio_best(ret, tmpio);
Tetsuo Handa612dafa2017-02-22 15:40:50 -0800229 }
Jens Axboe22e2c502005-06-27 10:55:12 +0200230
231 if (who)
232 free_uid(user);
233 break;
234 default:
235 ret = -EINVAL;
236 }
237
Greg Thelend69b78b2010-11-15 10:20:52 +0100238 rcu_read_unlock();
Jens Axboe22e2c502005-06-27 10:55:12 +0200239 return ret;
240}