[linux.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 <linux/module.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	12	#include <linux/device-mapper.h>
056075c7	13	#include <linux/module.h>
586e80e6	14
1da177e4 LT	15	#include "dm-path-selector.h"
	16
	17	#include <linux/slab.h>
	18
	19	struct ps_internal {
	20	struct path_selector_type pst;
1da177e4	21	struct list_head list;
1da177e4 LT	22	};
	23
	24	#define pst_to_psi(__pst) container_of((__pst), struct ps_internal, pst)
	25
	26	static LIST_HEAD(_path_selectors);
	27	static DECLARE_RWSEM(_ps_lock);
	28
5e198d94	29	static struct ps_internal __find_path_selector_type(const char name)
1da177e4 LT	30	{
	31	struct ps_internal *psi;
	32
	33	list_for_each_entry(psi, &_path_selectors, list) {
	34	if (!strcmp(name, psi->pst.name))
	35	return psi;
	36	}
	37
	38	return NULL;
	39	}
	40
	41	static struct ps_internal get_path_selector(const char name)
	42	{
	43	struct ps_internal *psi;
	44
	45	down_read(&_ps_lock);
	46	psi = __find_path_selector_type(name);
aea90588 JN	47	if (psi && !try_module_get(psi->pst.module))
aea90588 JN	48	psi = NULL;
1da177e4 LT	49	up_read(&_ps_lock);
	50
	51	return psi;
	52	}
	53
	54	struct path_selector_type dm_get_path_selector(const char name)
	55	{
	56	struct ps_internal *psi;
	57
	58	if (!name)
	59	return NULL;
	60
	61	psi = get_path_selector(name);
	62	if (!psi) {
	63	request_module("dm-%s", name);
	64	psi = get_path_selector(name);
	65	}
	66
	67	return psi ? &psi->pst : NULL;
	68	}
	69
	70	void dm_put_path_selector(struct path_selector_type *pst)
	71	{
	72	struct ps_internal *psi;
	73
	74	if (!pst)
	75	return;
	76
	77	down_read(&_ps_lock);
	78	psi = __find_path_selector_type(pst->name);
	79	if (!psi)
	80	goto out;
	81
aea90588	82	module_put(psi->pst.module);
1da177e4 LT	83	out:
	84	up_read(&_ps_lock);
	85	}
	86
	87	static struct ps_internal _alloc_path_selector(struct path_selector_type pst)
	88	{
094262db	89	struct ps_internal psi = kzalloc(sizeof(psi), GFP_KERNEL);
1da177e4	90
094262db	91	if (psi)
1da177e4	92	psi->pst = *pst;
1da177e4 LT	93
	94	return psi;
	95	}
	96
	97	int dm_register_path_selector(struct path_selector_type *pst)
	98	{
	99	int r = 0;
	100	struct ps_internal *psi = _alloc_path_selector(pst);
	101
	102	if (!psi)
	103	return -ENOMEM;
	104
	105	down_write(&_ps_lock);
	106
	107	if (__find_path_selector_type(pst->name)) {
	108	kfree(psi);
	109	r = -EEXIST;
	110	} else
	111	list_add(&psi->list, &_path_selectors);
	112
	113	up_write(&_ps_lock);
	114
	115	return r;
	116	}
	117
	118	int dm_unregister_path_selector(struct path_selector_type *pst)
	119	{
	120	struct ps_internal *psi;
	121
	122	down_write(&_ps_lock);
	123
	124	psi = __find_path_selector_type(pst->name);
	125	if (!psi) {
	126	up_write(&_ps_lock);
	127	return -EINVAL;
	128	}
	129
1da177e4 LT	130	list_del(&psi->list);
	131
	132	up_write(&_ps_lock);
	133
	134	kfree(psi);
	135
	136	return 0;
	137	}
	138
	139	EXPORT_SYMBOL_GPL(dm_register_path_selector);
	140	EXPORT_SYMBOL_GPL(dm_unregister_path_selector);