[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>

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

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

	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)
					break;
			} while_each_thread(g, p);

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

	read_unlock_irq(&tasklist_lock);
	return ret;
}

asmlinkage long sys_ioprio_get(int which, int who)
{
	struct task_struct *g, *p;
	struct user_struct *user;
	int 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 = p->ioprio;
			break;
		case IOPRIO_WHO_PGRP:
			if (!who)
				who = process_group(current);
			do_each_task_pid(who, PIDTYPE_PGID, p) {
				if (ret == -ESRCH)
					ret = p->ioprio;
				else
					ret = ioprio_best(ret, p->ioprio);
			} 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;
				if (ret == -ESRCH)
					ret = p->ioprio;
				else
					ret = ioprio_best(ret, p->ioprio);
			} 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>
	25
	26	static int set_task_ioprio(struct task_struct *task, int ioprio)
	27	{
	28	struct io_context *ioc;
	29
	30	if (task->uid != current->euid &&
	31	task->uid != current->uid && !capable(CAP_SYS_NICE))
	32	return -EPERM;
	33
	34	task_lock(task);
	35
	36	task->ioprio = ioprio;
	37
	38	ioc = task->io_context;
	39	if (ioc && ioc->set_ioprio)
	40	ioc->set_ioprio(ioc, ioprio);
	41
	42	task_unlock(task);
	43	return 0;
	44	}
	45
cf366808	46	asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
22e2c507 JA	47	{
	48	int class = IOPRIO_PRIO_CLASS(ioprio);
	49	int data = IOPRIO_PRIO_DATA(ioprio);
	50	struct task_struct p, g;
	51	struct user_struct *user;
	52	int ret;
	53
	54	switch (class) {
	55	case IOPRIO_CLASS_RT:
	56	if (!capable(CAP_SYS_ADMIN))
	57	return -EPERM;
	58	/* fall through, rt has prio field too */
	59	case IOPRIO_CLASS_BE:
	60	if (data >= IOPRIO_BE_NR \|\| data < 0)
	61	return -EINVAL;
	62
	63	break;
	64	case IOPRIO_CLASS_IDLE:
f6fdd7d9 LT	65	if (!capable(CAP_SYS_ADMIN))
f6fdd7d9 LT	66	return -EPERM;
22e2c507 JA	67	break;
	68	default:
	69	return -EINVAL;
	70	}
	71
	72	ret = -ESRCH;
	73	read_lock_irq(&tasklist_lock);
	74	switch (which) {
	75	case IOPRIO_WHO_PROCESS:
	76	if (!who)
	77	p = current;
	78	else
	79	p = find_task_by_pid(who);
	80	if (p)
	81	ret = set_task_ioprio(p, ioprio);
	82	break;
	83	case IOPRIO_WHO_PGRP:
	84	if (!who)
	85	who = process_group(current);
	86	do_each_task_pid(who, PIDTYPE_PGID, p) {
	87	ret = set_task_ioprio(p, ioprio);
	88	if (ret)
	89	break;
	90	} while_each_task_pid(who, PIDTYPE_PGID, p);
	91	break;
	92	case IOPRIO_WHO_USER:
	93	if (!who)
	94	user = current->user;
	95	else
	96	user = find_user(who);
	97
	98	if (!user)
	99	break;
	100
	101	do_each_thread(g, p) {
	102	if (p->uid != who)
	103	continue;
	104	ret = set_task_ioprio(p, ioprio);
	105	if (ret)
	106	break;
	107	} while_each_thread(g, p);
	108
	109	if (who)
	110	free_uid(user);
	111	break;
	112	default:
	113	ret = -EINVAL;
	114	}
	115
	116	read_unlock_irq(&tasklist_lock);
	117	return ret;
	118	}
	119
cf366808	120	asmlinkage long sys_ioprio_get(int which, int who)
22e2c507 JA	121	{
	122	struct task_struct g, p;
	123	struct user_struct *user;
	124	int ret = -ESRCH;
	125
	126	read_lock_irq(&tasklist_lock);
	127	switch (which) {
	128	case IOPRIO_WHO_PROCESS:
	129	if (!who)
	130	p = current;
	131	else
	132	p = find_task_by_pid(who);
	133	if (p)
	134	ret = p->ioprio;
	135	break;
	136	case IOPRIO_WHO_PGRP:
	137	if (!who)
	138	who = process_group(current);
	139	do_each_task_pid(who, PIDTYPE_PGID, p) {
	140	if (ret == -ESRCH)
	141	ret = p->ioprio;
	142	else
	143	ret = ioprio_best(ret, p->ioprio);
	144	} while_each_task_pid(who, PIDTYPE_PGID, p);
	145	break;
	146	case IOPRIO_WHO_USER:
	147	if (!who)
	148	user = current->user;
	149	else
	150	user = find_user(who);
	151
	152	if (!user)
	153	break;
	154
	155	do_each_thread(g, p) {
	156	if (p->uid != user->uid)
	157	continue;
	158	if (ret == -ESRCH)
	159	ret = p->ioprio;
	160	else
	161	ret = ioprio_best(ret, p->ioprio);
	162	} while_each_thread(g, p);
	163
	164	if (who)
	165	free_uid(user);
	166	break;
	167	default:
	168	ret = -EINVAL;
	169	}
	170
	171	read_unlock_irq(&tasklist_lock);
	172	return ret;
	173	}
	174