[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;
	/* see wmb() in current_io_context() */
	smp_read_barrier_depends();

	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;
9f83e45e ON	47	/* see wmb() in current_io_context() */
	48	smp_read_barrier_depends();
	49
22e2c507 JA	50	if (ioc && ioc->set_ioprio)
	51	ioc->set_ioprio(ioc, ioprio);
	52
	53	task_unlock(task);
	54	return 0;
	55	}
	56
cf366808	57	asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
22e2c507 JA	58	{
	59	int class = IOPRIO_PRIO_CLASS(ioprio);
	60	int data = IOPRIO_PRIO_DATA(ioprio);
	61	struct task_struct p, g;
	62	struct user_struct *user;
	63	int ret;
	64
	65	switch (class) {
	66	case IOPRIO_CLASS_RT:
	67	if (!capable(CAP_SYS_ADMIN))
	68	return -EPERM;
	69	/* fall through, rt has prio field too */
	70	case IOPRIO_CLASS_BE:
	71	if (data >= IOPRIO_BE_NR \|\| data < 0)
	72	return -EINVAL;
	73
	74	break;
	75	case IOPRIO_CLASS_IDLE:
f6fdd7d9 LT	76	if (!capable(CAP_SYS_ADMIN))
f6fdd7d9 LT	77	return -EPERM;
22e2c507 JA	78	break;
	79	default:
	80	return -EINVAL;
	81	}
	82
	83	ret = -ESRCH;
	84	read_lock_irq(&tasklist_lock);
	85	switch (which) {
	86	case IOPRIO_WHO_PROCESS:
	87	if (!who)
	88	p = current;
	89	else
	90	p = find_task_by_pid(who);
	91	if (p)
	92	ret = set_task_ioprio(p, ioprio);
	93	break;
	94	case IOPRIO_WHO_PGRP:
	95	if (!who)
	96	who = process_group(current);
	97	do_each_task_pid(who, PIDTYPE_PGID, p) {
	98	ret = set_task_ioprio(p, ioprio);
	99	if (ret)
	100	break;
	101	} while_each_task_pid(who, PIDTYPE_PGID, p);
	102	break;
	103	case IOPRIO_WHO_USER:
	104	if (!who)
	105	user = current->user;
	106	else
	107	user = find_user(who);
	108
	109	if (!user)
	110	break;
	111
	112	do_each_thread(g, p) {
	113	if (p->uid != who)
	114	continue;
	115	ret = set_task_ioprio(p, ioprio);
	116	if (ret)
78bd4d48	117	goto free_uid;
22e2c507	118	} while_each_thread(g, p);
78bd4d48	119	free_uid:
22e2c507 JA	120	if (who)
	121	free_uid(user);
	122	break;
	123	default:
	124	ret = -EINVAL;
	125	}
	126
	127	read_unlock_irq(&tasklist_lock);
	128	return ret;
	129	}
	130
a1836a42 DQ	131	static int get_task_ioprio(struct task_struct *p)
	132	{
	133	int ret;
	134
	135	ret = security_task_getioprio(p);
	136	if (ret)
	137	goto out;
	138	ret = p->ioprio;
	139	out:
	140	return ret;
	141	}
	142
cf366808	143	asmlinkage long sys_ioprio_get(int which, int who)
22e2c507 JA	144	{
	145	struct task_struct g, p;
	146	struct user_struct *user;
	147	int ret = -ESRCH;
a1836a42	148	int tmpio;
22e2c507 JA	149
	150	read_lock_irq(&tasklist_lock);
	151	switch (which) {
	152	case IOPRIO_WHO_PROCESS:
	153	if (!who)
	154	p = current;
	155	else
	156	p = find_task_by_pid(who);
	157	if (p)
a1836a42	158	ret = get_task_ioprio(p);
22e2c507 JA	159	break;
	160	case IOPRIO_WHO_PGRP:
	161	if (!who)
	162	who = process_group(current);
	163	do_each_task_pid(who, PIDTYPE_PGID, p) {
a1836a42 DQ	164	tmpio = get_task_ioprio(p);
	165	if (tmpio < 0)
	166	continue;
22e2c507	167	if (ret == -ESRCH)
a1836a42	168	ret = tmpio;
22e2c507	169	else
a1836a42	170	ret = ioprio_best(ret, tmpio);
22e2c507 JA	171	} while_each_task_pid(who, PIDTYPE_PGID, p);
	172	break;
	173	case IOPRIO_WHO_USER:
	174	if (!who)
	175	user = current->user;
	176	else
	177	user = find_user(who);
	178
	179	if (!user)
	180	break;
	181
	182	do_each_thread(g, p) {
	183	if (p->uid != user->uid)
	184	continue;
a1836a42 DQ	185	tmpio = get_task_ioprio(p);
	186	if (tmpio < 0)
	187	continue;
22e2c507	188	if (ret == -ESRCH)
a1836a42	189	ret = tmpio;
22e2c507	190	else
a1836a42	191	ret = ioprio_best(ret, tmpio);
22e2c507 JA	192	} while_each_thread(g, p);
	193
	194	if (who)
	195	free_uid(user);
	196	break;
	197	default:
	198	ret = -EINVAL;
	199	}
	200
	201	read_unlock_irq(&tasklist_lock);
	202	return ret;
	203	}
	204