[net-next-2.6.git] / fs / ioprio.c

/*
 * fs/ioprio.c
 *
 * Copyright (C) 2004 Jens Axboe <axboe@suse.de>
 *
 * Helper functions for setting/querying io priorities of processes. The
 * system calls closely mimmick getpriority/setpriority, see the man page for
 * those. The prio argument is a composite of prio class and prio data, where
 * the data argument has meaning within that class. The standard scheduling
 * classes have 8 distinct prio levels, with 0 being the highest prio and 7
 * being the lowest.
 *
 * IOW, setting BE scheduling class with prio 2 is done ala:
 *
 * unsigned int prio = (IOPRIO_CLASS_BE << IOPRIO_CLASS_SHIFT) | 2;
 *
 * ioprio_set(PRIO_PROCESS, pid, prio);
 *
 * See also Documentation/block/ioprio.txt
 *
 */
#include <linux/kernel.h>
#include <linux/ioprio.h>
#include <linux/blkdev.h>
#include <linux/capability.h>
#include <linux/syscalls.h>
#include <linux/security.h>

static int set_task_ioprio(struct task_struct *task, int ioprio)
{
	int err;
	struct io_context *ioc;

	if (task->uid != current->euid &&
	    task->uid != current->uid && !capable(CAP_SYS_NICE))
		return -EPERM;

	err = security_task_setioprio(task, ioprio);
	if (err)
		return err;

	task_lock(task);

	task->ioprio = ioprio;

	ioc = task->io_context;
	if (ioc && ioc->set_ioprio)
		ioc->set_ioprio(ioc, ioprio);

	task_unlock(task);
	return 0;
}

asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
{
	int class = IOPRIO_PRIO_CLASS(ioprio);
	int data = IOPRIO_PRIO_DATA(ioprio);
	struct task_struct *p, *g;
	struct user_struct *user;
	int ret;

	switch (class) {
		case IOPRIO_CLASS_RT:
			if (!capable(CAP_SYS_ADMIN))
				return -EPERM;
			/* fall through, rt has prio field too */
		case IOPRIO_CLASS_BE:
			if (data >= IOPRIO_BE_NR || data < 0)
				return -EINVAL;

			break;
		case IOPRIO_CLASS_IDLE:
			if (!capable(CAP_SYS_ADMIN))
				return -EPERM;
			break;
		default:
			return -EINVAL;
	}

	ret = -ESRCH;
	read_lock_irq(&tasklist_lock);
	switch (which) {
		case IOPRIO_WHO_PROCESS:
			if (!who)
				p = current;
			else
				p = find_task_by_pid(who);
			if (p)
				ret = set_task_ioprio(p, ioprio);
			break;
		case IOPRIO_WHO_PGRP:
			if (!who)
				who = process_group(current);
			do_each_task_pid(who, PIDTYPE_PGID, p) {
				ret = set_task_ioprio(p, ioprio);
				if (ret)
					break;
			} while_each_task_pid(who, PIDTYPE_PGID, p);
			break;
		case IOPRIO_WHO_USER:
			if (!who)
				user = current->user;
			else
				user = find_user(who);

			if (!user)
				break;

			do_each_thread(g, p) {
				if (p->uid != who)
					continue;
				ret = set_task_ioprio(p, ioprio);
				if (ret)
					goto free_uid;
			} while_each_thread(g, p);
free_uid:
			if (who)
				free_uid(user);
			break;
		default:
			ret = -EINVAL;
	}

	read_unlock_irq(&tasklist_lock);
	return ret;
}

static int get_task_ioprio(struct task_struct *p)
{
	int ret;

	ret = security_task_getioprio(p);
	if (ret)
		goto out;
	ret = p->ioprio;
out:
	return ret;
}

asmlinkage long sys_ioprio_get(int which, int who)
{
	struct task_struct *g, *p;
	struct user_struct *user;
	int ret = -ESRCH;
	int tmpio;

	read_lock_irq(&tasklist_lock);
	switch (which) {
		case IOPRIO_WHO_PROCESS:
			if (!who)
				p = current;
			else
				p = find_task_by_pid(who);
			if (p)
				ret = get_task_ioprio(p);
			break;
		case IOPRIO_WHO_PGRP:
			if (!who)
				who = process_group(current);
			do_each_task_pid(who, PIDTYPE_PGID, p) {
				tmpio = get_task_ioprio(p);
				if (tmpio < 0)
					continue;
				if (ret == -ESRCH)
					ret = tmpio;
				else
					ret = ioprio_best(ret, tmpio);
			} while_each_task_pid(who, PIDTYPE_PGID, p);
			break;
		case IOPRIO_WHO_USER:
			if (!who)
				user = current->user;
			else
				user = find_user(who);

			if (!user)
				break;

			do_each_thread(g, p) {
				if (p->uid != user->uid)
					continue;
				tmpio = get_task_ioprio(p);
				if (tmpio < 0)
					continue;
				if (ret == -ESRCH)
					ret = tmpio;
				else
					ret = ioprio_best(ret, tmpio);
			} while_each_thread(g, p);

			if (who)
				free_uid(user);
			break;
		default:
			ret = -EINVAL;
	}

	read_unlock_irq(&tasklist_lock);
	return ret;
}
Commit	Line	Data
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))
f6fdd7d9 LT	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)
78bd4d48	114	goto free_uid;
22e2c507	115	} while_each_thread(g, p);
78bd4d48	116	free_uid:
22e2c507 JA	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