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
12#include <linux/device-mapper.h>
13#include <linux/module.h>
14
15#include "dm-path-selector.h"
16
17#include <linux/slab.h>
18
19struct ps_internal {
20	struct path_selector_type pst;
21	struct list_head list;
22};
23
24#define pst_to_psi(__pst) container_of((__pst), struct ps_internal, pst)
25
26static LIST_HEAD(_path_selectors);
27static DECLARE_RWSEM(_ps_lock);
28
29static struct ps_internal *__find_path_selector_type(const char *name)
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
41static 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);
47	if (psi && !try_module_get(psi->pst.module))
48		psi = NULL;
49	up_read(&_ps_lock);
50
51	return psi;
52}
53
54struct 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
70void 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
82	module_put(psi->pst.module);
83out:
84	up_read(&_ps_lock);
85}
86
87static struct ps_internal *_alloc_path_selector(struct path_selector_type *pst)
88{
89	struct ps_internal *psi = kzalloc(sizeof(*psi), GFP_KERNEL);
90
91	if (psi)
92		psi->pst = *pst;
93
94	return psi;
95}
96
97int 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
118int 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
130	list_del(&psi->list);
131
132	up_write(&_ps_lock);
133
134	kfree(psi);
135
136	return 0;
137}
138
139EXPORT_SYMBOL_GPL(dm_register_path_selector);
140EXPORT_SYMBOL_GPL(dm_unregister_path_selector);
141