[linux.git] / fs / ioprio.c

/*
 * fs/ioprio.c
 *
 * Copyright (C) 2004 Jens Axboe <[email protected]>
 *
 * 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>

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 <[email protected]>
	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>
22e2c507 JA	27
	28	static int set_task_ioprio(struct task_struct *task, int ioprio)
	29	{
	30	struct io_context *ioc;
	31
	32	if (task->uid != current->euid &&
	33	task->uid != current->uid && !capable(CAP_SYS_NICE))
	34	return -EPERM;
	35
	36	task_lock(task);
	37
	38	task->ioprio = ioprio;
	39
	40	ioc = task->io_context;
	41	if (ioc && ioc->set_ioprio)
	42	ioc->set_ioprio(ioc, ioprio);
	43
	44	task_unlock(task);
	45	return 0;
	46	}
	47
cf366808	48	asmlinkage long sys_ioprio_set(int which, int who, int ioprio)
22e2c507 JA	49	{
	50	int class = IOPRIO_PRIO_CLASS(ioprio);
	51	int data = IOPRIO_PRIO_DATA(ioprio);
	52	struct task_struct p, g;
	53	struct user_struct *user;
	54	int ret;
	55
	56	switch (class) {
	57	case IOPRIO_CLASS_RT:
	58	if (!capable(CAP_SYS_ADMIN))
	59	return -EPERM;
	60	/* fall through, rt has prio field too */
	61	case IOPRIO_CLASS_BE:
	62	if (data >= IOPRIO_BE_NR \|\| data < 0)
	63	return -EINVAL;
	64
	65	break;
	66	case IOPRIO_CLASS_IDLE:
f6fdd7d9 LT	67	if (!capable(CAP_SYS_ADMIN))
f6fdd7d9 LT	68	return -EPERM;
22e2c507 JA	69	break;
	70	default:
	71	return -EINVAL;
	72	}
	73
	74	ret = -ESRCH;
	75	read_lock_irq(&tasklist_lock);
	76	switch (which) {
	77	case IOPRIO_WHO_PROCESS:
	78	if (!who)
	79	p = current;
	80	else
	81	p = find_task_by_pid(who);
	82	if (p)
	83	ret = set_task_ioprio(p, ioprio);
	84	break;
	85	case IOPRIO_WHO_PGRP:
	86	if (!who)
	87	who = process_group(current);
	88	do_each_task_pid(who, PIDTYPE_PGID, p) {
	89	ret = set_task_ioprio(p, ioprio);
	90	if (ret)
	91	break;
	92	} while_each_task_pid(who, PIDTYPE_PGID, p);
	93	break;
	94	case IOPRIO_WHO_USER:
	95	if (!who)
	96	user = current->user;
	97	else
	98	user = find_user(who);
	99
	100	if (!user)
	101	break;
	102
	103	do_each_thread(g, p) {
	104	if (p->uid != who)
	105	continue;
	106	ret = set_task_ioprio(p, ioprio);
	107	if (ret)
	108	break;
	109	} while_each_thread(g, p);
	110
	111	if (who)
	112	free_uid(user);
	113	break;
	114	default:
	115	ret = -EINVAL;
	116	}
	117
	118	read_unlock_irq(&tasklist_lock);
	119	return ret;
	120	}
	121
cf366808	122	asmlinkage long sys_ioprio_get(int which, int who)
22e2c507 JA	123	{
	124	struct task_struct g, p;
	125	struct user_struct *user;
	126	int ret = -ESRCH;
	127
	128	read_lock_irq(&tasklist_lock);
	129	switch (which) {
	130	case IOPRIO_WHO_PROCESS:
	131	if (!who)
	132	p = current;
	133	else
	134	p = find_task_by_pid(who);
	135	if (p)
	136	ret = p->ioprio;
	137	break;
	138	case IOPRIO_WHO_PGRP:
	139	if (!who)
	140	who = process_group(current);
	141	do_each_task_pid(who, PIDTYPE_PGID, p) {
	142	if (ret == -ESRCH)
	143	ret = p->ioprio;
	144	else
	145	ret = ioprio_best(ret, p->ioprio);
	146	} while_each_task_pid(who, PIDTYPE_PGID, p);
	147	break;
	148	case IOPRIO_WHO_USER:
	149	if (!who)
	150	user = current->user;
	151	else
	152	user = find_user(who);
	153
	154	if (!user)
	155	break;
	156
	157	do_each_thread(g, p) {
	158	if (p->uid != user->uid)
	159	continue;
	160	if (ret == -ESRCH)
	161	ret = p->ioprio;
	162	else
	163	ret = ioprio_best(ret, p->ioprio);
	164	} while_each_thread(g, p);
	165
	166	if (who)
	167	free_uid(user);
	168	break;
	169	default:
	170	ret = -EINVAL;
	171	}
	172
	173	read_unlock_irq(&tasklist_lock);
	174	return ret;
	175	}
	176