[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>

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 int 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:
			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 int 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>
	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
	46	asmlinkage int sys_ioprio_set(int which, int who, int ioprio)
	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:
65	break;
66	default:
67	return -EINVAL;
68	}
69
70	ret = -ESRCH;
71	read_lock_irq(&tasklist_lock);
72	switch (which) {
73	case IOPRIO_WHO_PROCESS:
74	if (!who)
75	p = current;
76	else
77	p = find_task_by_pid(who);
78	if (p)
79	ret = set_task_ioprio(p, ioprio);
80	break;
81	case IOPRIO_WHO_PGRP:
82	if (!who)
83	who = process_group(current);
84	do_each_task_pid(who, PIDTYPE_PGID, p) {
85	ret = set_task_ioprio(p, ioprio);
86	if (ret)
87	break;
88	} while_each_task_pid(who, PIDTYPE_PGID, p);
89	break;
90	case IOPRIO_WHO_USER:
91	if (!who)
92	user = current->user;
93	else
94	user = find_user(who);
95
96	if (!user)
97	break;
98
99	do_each_thread(g, p) {
100	if (p->uid != who)
101	continue;
102	ret = set_task_ioprio(p, ioprio);
103	if (ret)
104	break;
105	} while_each_thread(g, p);
106
107	if (who)
108	free_uid(user);
109	break;
110	default:
111	ret = -EINVAL;
112	}
113
114	read_unlock_irq(&tasklist_lock);
115	return ret;
116	}
117
118	asmlinkage int sys_ioprio_get(int which, int who)
119	{
120	struct task_struct g, p;
121	struct user_struct *user;
122	int ret = -ESRCH;
123
124	read_lock_irq(&tasklist_lock);
125	switch (which) {
126	case IOPRIO_WHO_PROCESS:
127	if (!who)
128	p = current;
129	else
130	p = find_task_by_pid(who);
131	if (p)
132	ret = p->ioprio;
133	break;
134	case IOPRIO_WHO_PGRP:
135	if (!who)
136	who = process_group(current);
137	do_each_task_pid(who, PIDTYPE_PGID, p) {
138	if (ret == -ESRCH)
139	ret = p->ioprio;
140	else
141	ret = ioprio_best(ret, p->ioprio);
142	} while_each_task_pid(who, PIDTYPE_PGID, p);
143	break;
144	case IOPRIO_WHO_USER:
145	if (!who)
146	user = current->user;
147	else
148	user = find_user(who);
149
150	if (!user)
151	break;
152
153	do_each_thread(g, p) {
154	if (p->uid != user->uid)
155	continue;
156	if (ret == -ESRCH)
157	ret = p->ioprio;
158	else
159	ret = ioprio_best(ret, p->ioprio);
160	} while_each_thread(g, p);
161
162	if (who)
163	free_uid(user);
164	break;
165	default:
166	ret = -EINVAL;
167	}
168
169	read_unlock_irq(&tasklist_lock);
170	return ret;
171	}
172