[net-next-2.6.git] / drivers / md / dm-path-selector.c

/*
 * Copyright (C) 2003 Sistina Software.
 * Copyright (C) 2004 Red Hat, Inc. All rights reserved.
 *
 * Module Author: Heinz Mauelshagen
 *
 * This file is released under the GPL.
 *
 * Path selector registration.
 */

#include <linux/device-mapper.h>

#include "dm-path-selector.h"

#include <linux/slab.h>

struct ps_internal {
	struct path_selector_type pst;
	struct list_head list;
};

#define pst_to_psi(__pst) container_of((__pst), struct ps_internal, pst)

static LIST_HEAD(_path_selectors);
static DECLARE_RWSEM(_ps_lock);

static struct ps_internal *__find_path_selector_type(const char *name)
{
	struct ps_internal *psi;

	list_for_each_entry(psi, &_path_selectors, list) {
		if (!strcmp(name, psi->pst.name))
			return psi;
	}

	return NULL;
}

static struct ps_internal *get_path_selector(const char *name)
{
	struct ps_internal *psi;

	down_read(&_ps_lock);
	psi = __find_path_selector_type(name);
	if (psi && !try_module_get(psi->pst.module))
		psi = NULL;
	up_read(&_ps_lock);

	return psi;
}

struct path_selector_type *dm_get_path_selector(const char *name)
{
	struct ps_internal *psi;

	if (!name)
		return NULL;

	psi = get_path_selector(name);
	if (!psi) {
		request_module("dm-%s", name);
		psi = get_path_selector(name);
	}

	return psi ? &psi->pst : NULL;
}

void dm_put_path_selector(struct path_selector_type *pst)
{
	struct ps_internal *psi;

	if (!pst)
		return;

	down_read(&_ps_lock);
	psi = __find_path_selector_type(pst->name);
	if (!psi)
		goto out;

	module_put(psi->pst.module);
out:
	up_read(&_ps_lock);
}

static struct ps_internal *_alloc_path_selector(struct path_selector_type *pst)
{
	struct ps_internal *psi = kzalloc(sizeof(*psi), GFP_KERNEL);

	if (psi)
		psi->pst = *pst;

	return psi;
}

int dm_register_path_selector(struct path_selector_type *pst)
{
	int r = 0;
	struct ps_internal *psi = _alloc_path_selector(pst);

	if (!psi)
		return -ENOMEM;

	down_write(&_ps_lock);

	if (__find_path_selector_type(pst->name)) {
		kfree(psi);
		r = -EEXIST;
	} else
		list_add(&psi->list, &_path_selectors);

	up_write(&_ps_lock);

	return r;
}

int dm_unregister_path_selector(struct path_selector_type *pst)
{
	struct ps_internal *psi;

	down_write(&_ps_lock);

	psi = __find_path_selector_type(pst->name);
	if (!psi) {
		up_write(&_ps_lock);
		return -EINVAL;
	}

	list_del(&psi->list);

	up_write(&_ps_lock);

	kfree(psi);

	return 0;
}

EXPORT_SYMBOL_GPL(dm_register_path_selector);
EXPORT_SYMBOL_GPL(dm_unregister_path_selector);
Commit	Line	Data
1da177e4 LT	1	/*
	2	* Copyright (C) 2003 Sistina Software.
	3	* Copyright (C) 2004 Red Hat, Inc. All rights reserved.
	4	*
	5	* Module Author: Heinz Mauelshagen
	6	*
	7	* This file is released under the GPL.
	8	*
	9	* Path selector registration.
	10	*/
	11
586e80e6 MP	12	#include <linux/device-mapper.h>
586e80e6 MP	13
1da177e4 LT	14	#include "dm-path-selector.h"
	15
	16	#include <linux/slab.h>
	17
	18	struct ps_internal {
	19	struct path_selector_type pst;
1da177e4	20	struct list_head list;
1da177e4 LT	21	};
	22
	23	#define pst_to_psi(__pst) container_of((__pst), struct ps_internal, pst)
	24
	25	static LIST_HEAD(_path_selectors);
	26	static DECLARE_RWSEM(_ps_lock);
	27
5e198d94	28	static struct ps_internal __find_path_selector_type(const char name)
1da177e4 LT	29	{
	30	struct ps_internal *psi;
	31
	32	list_for_each_entry(psi, &_path_selectors, list) {
	33	if (!strcmp(name, psi->pst.name))
	34	return psi;
	35	}
	36
	37	return NULL;
	38	}
	39
	40	static struct ps_internal get_path_selector(const char name)
	41	{
	42	struct ps_internal *psi;
	43
	44	down_read(&_ps_lock);
	45	psi = __find_path_selector_type(name);
aea90588 JN	46	if (psi && !try_module_get(psi->pst.module))
aea90588 JN	47	psi = NULL;
1da177e4 LT	48	up_read(&_ps_lock);
	49
	50	return psi;
	51	}
	52
	53	struct path_selector_type dm_get_path_selector(const char name)
	54	{
	55	struct ps_internal *psi;
	56
	57	if (!name)
	58	return NULL;
	59
	60	psi = get_path_selector(name);
	61	if (!psi) {
	62	request_module("dm-%s", name);
	63	psi = get_path_selector(name);
	64	}
	65
	66	return psi ? &psi->pst : NULL;
	67	}
	68
	69	void dm_put_path_selector(struct path_selector_type *pst)
	70	{
	71	struct ps_internal *psi;
	72
	73	if (!pst)
	74	return;
	75
	76	down_read(&_ps_lock);
	77	psi = __find_path_selector_type(pst->name);
	78	if (!psi)
	79	goto out;
	80
aea90588	81	module_put(psi->pst.module);
1da177e4 LT	82	out:
	83	up_read(&_ps_lock);
	84	}
	85
	86	static struct ps_internal _alloc_path_selector(struct path_selector_type pst)
	87	{
094262db	88	struct ps_internal psi = kzalloc(sizeof(psi), GFP_KERNEL);
1da177e4	89
094262db	90	if (psi)
1da177e4	91	psi->pst = *pst;
1da177e4 LT	92
	93	return psi;
	94	}
	95
	96	int dm_register_path_selector(struct path_selector_type *pst)
	97	{
	98	int r = 0;
	99	struct ps_internal *psi = _alloc_path_selector(pst);
	100
	101	if (!psi)
	102	return -ENOMEM;
	103
	104	down_write(&_ps_lock);
	105
	106	if (__find_path_selector_type(pst->name)) {
	107	kfree(psi);
	108	r = -EEXIST;
	109	} else
	110	list_add(&psi->list, &_path_selectors);
	111
	112	up_write(&_ps_lock);
	113
	114	return r;
	115	}
	116
	117	int dm_unregister_path_selector(struct path_selector_type *pst)
	118	{
	119	struct ps_internal *psi;
	120
	121	down_write(&_ps_lock);
	122
	123	psi = __find_path_selector_type(pst->name);
	124	if (!psi) {
	125	up_write(&_ps_lock);
	126	return -EINVAL;
	127	}
	128
1da177e4 LT	129	list_del(&psi->list);
	130
	131	up_write(&_ps_lock);
	132
	133	kfree(psi);
	134
	135	return 0;
	136	}
	137
	138	EXPORT_SYMBOL_GPL(dm_register_path_selector);
	139	EXPORT_SYMBOL_GPL(dm_unregister_path_selector);