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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 | |
19 | struct 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 | |
26 | static LIST_HEAD(_path_selectors); |
27 | static DECLARE_RWSEM(_ps_lock); |
28 | |
29 | static 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 | |
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); |
47 | if (psi && !try_module_get(psi->pst.module)) |
48 | psi = NULL; |
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 | |
82 | module_put(psi->pst.module); |
83 | out: |
84 | up_read(&_ps_lock); |
85 | } |
86 | |
87 | static 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 | |
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 | |
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); |
141 |
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