[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/syscalls.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>
9abdc4cd	25	#include <linux/syscalls.h>
22e2c507 JA	26
	27	static int set_task_ioprio(struct task_struct *task, int ioprio)
	28	{
	29	struct io_context *ioc;
	30
	31	if (task->uid != current->euid &&
	32	task->uid != current->uid && !capable(CAP_SYS_NICE))
	33	return -EPERM;
	34
	35	task_lock(task);
	36
	37	task->ioprio = ioprio;
	38
	39	ioc = task->io_context;
	40	if (ioc && ioc->set_ioprio)
	41	ioc->set_ioprio(ioc, ioprio);
	42
	43	task_unlock(task);
	44	return 0;
	45	}
	46
cf366808	47	asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
22e2c507 JA	48	{
	49	int class = IOPRIO_PRIO_CLASS(ioprio);
	50	int data = IOPRIO_PRIO_DATA(ioprio);
	51	struct task_struct p, g;
	52	struct user_struct *user;
	53	int ret;
	54
	55	switch (class) {
	56	case IOPRIO_CLASS_RT:
	57	if (!capable(CAP_SYS_ADMIN))
	58	return -EPERM;
	59	/* fall through, rt has prio field too */
	60	case IOPRIO_CLASS_BE:
	61	if (data >= IOPRIO_BE_NR \|\| data < 0)
	62	return -EINVAL;
	63
	64	break;
	65	case IOPRIO_CLASS_IDLE:
f6fdd7d9 LT	66	if (!capable(CAP_SYS_ADMIN))
f6fdd7d9 LT	67	return -EPERM;
22e2c507 JA	68	break;
	69	default:
	70	return -EINVAL;
	71	}
	72
	73	ret = -ESRCH;
	74	read_lock_irq(&tasklist_lock);
	75	switch (which) {
	76	case IOPRIO_WHO_PROCESS:
	77	if (!who)
	78	p = current;
	79	else
	80	p = find_task_by_pid(who);
	81	if (p)
	82	ret = set_task_ioprio(p, ioprio);
	83	break;
	84	case IOPRIO_WHO_PGRP:
	85	if (!who)
	86	who = process_group(current);
	87	do_each_task_pid(who, PIDTYPE_PGID, p) {
	88	ret = set_task_ioprio(p, ioprio);
	89	if (ret)
	90	break;
	91	} while_each_task_pid(who, PIDTYPE_PGID, p);
	92	break;
	93	case IOPRIO_WHO_USER:
	94	if (!who)
	95	user = current->user;
	96	else
	97	user = find_user(who);
	98
	99	if (!user)
	100	break;
	101
	102	do_each_thread(g, p) {
	103	if (p->uid != who)
	104	continue;
	105	ret = set_task_ioprio(p, ioprio);
	106	if (ret)
	107	break;
	108	} while_each_thread(g, p);
	109
	110	if (who)
	111	free_uid(user);
	112	break;
	113	default:
	114	ret = -EINVAL;
	115	}
	116
	117	read_unlock_irq(&tasklist_lock);
	118	return ret;
	119	}
	120
cf366808	121	asmlinkage long sys_ioprio_get(int which, int who)
22e2c507 JA	122	{
	123	struct task_struct g, p;
	124	struct user_struct *user;
	125	int ret = -ESRCH;
	126
	127	read_lock_irq(&tasklist_lock);
	128	switch (which) {
	129	case IOPRIO_WHO_PROCESS:
	130	if (!who)
	131	p = current;
	132	else
	133	p = find_task_by_pid(who);
	134	if (p)
	135	ret = p->ioprio;
	136	break;
	137	case IOPRIO_WHO_PGRP:
	138	if (!who)
	139	who = process_group(current);
	140	do_each_task_pid(who, PIDTYPE_PGID, p) {
	141	if (ret == -ESRCH)
	142	ret = p->ioprio;
	143	else
	144	ret = ioprio_best(ret, p->ioprio);
	145	} while_each_task_pid(who, PIDTYPE_PGID, p);
	146	break;
	147	case IOPRIO_WHO_USER:
	148	if (!who)
	149	user = current->user;
	150	else
	151	user = find_user(who);
	152
	153	if (!user)
	154	break;
	155
	156	do_each_thread(g, p) {
	157	if (p->uid != user->uid)
	158	continue;
	159	if (ret == -ESRCH)
	160	ret = p->ioprio;
	161	else
	162	ret = ioprio_best(ret, p->ioprio);
	163	} while_each_thread(g, p);
	164
	165	if (who)
	166	free_uid(user);
	167	break;
	168	default:
	169	ret = -EINVAL;
	170	}
	171
	172	read_unlock_irq(&tasklist_lock);
	173	return ret;
	174	}
	175