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