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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> |
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; | |
20 | ||
21 | struct list_head list; | |
22 | long use; | |
23 | }; | |
24 | ||
25 | #define pst_to_psi(__pst) container_of((__pst), struct ps_internal, pst) | |
26 | ||
27 | static LIST_HEAD(_path_selectors); | |
28 | static DECLARE_RWSEM(_ps_lock); | |
29 | ||
5e198d94 | 30 | static struct ps_internal *__find_path_selector_type(const char *name) |
1da177e4 LT |
31 | { |
32 | struct ps_internal *psi; | |
33 | ||
34 | list_for_each_entry(psi, &_path_selectors, list) { | |
35 | if (!strcmp(name, psi->pst.name)) | |
36 | return psi; | |
37 | } | |
38 | ||
39 | return NULL; | |
40 | } | |
41 | ||
42 | static struct ps_internal *get_path_selector(const char *name) | |
43 | { | |
44 | struct ps_internal *psi; | |
45 | ||
46 | down_read(&_ps_lock); | |
47 | psi = __find_path_selector_type(name); | |
48 | if (psi) { | |
49 | if ((psi->use == 0) && !try_module_get(psi->pst.module)) | |
50 | psi = NULL; | |
51 | else | |
52 | psi->use++; | |
53 | } | |
54 | up_read(&_ps_lock); | |
55 | ||
56 | return psi; | |
57 | } | |
58 | ||
59 | struct path_selector_type *dm_get_path_selector(const char *name) | |
60 | { | |
61 | struct ps_internal *psi; | |
62 | ||
63 | if (!name) | |
64 | return NULL; | |
65 | ||
66 | psi = get_path_selector(name); | |
67 | if (!psi) { | |
68 | request_module("dm-%s", name); | |
69 | psi = get_path_selector(name); | |
70 | } | |
71 | ||
72 | return psi ? &psi->pst : NULL; | |
73 | } | |
74 | ||
75 | void dm_put_path_selector(struct path_selector_type *pst) | |
76 | { | |
77 | struct ps_internal *psi; | |
78 | ||
79 | if (!pst) | |
80 | return; | |
81 | ||
82 | down_read(&_ps_lock); | |
83 | psi = __find_path_selector_type(pst->name); | |
84 | if (!psi) | |
85 | goto out; | |
86 | ||
87 | if (--psi->use == 0) | |
88 | module_put(psi->pst.module); | |
89 | ||
c163c729 | 90 | BUG_ON(psi->use < 0); |
1da177e4 LT |
91 | |
92 | out: | |
93 | up_read(&_ps_lock); | |
94 | } | |
95 | ||
96 | static struct ps_internal *_alloc_path_selector(struct path_selector_type *pst) | |
97 | { | |
094262db | 98 | struct ps_internal *psi = kzalloc(sizeof(*psi), GFP_KERNEL); |
1da177e4 | 99 | |
094262db | 100 | if (psi) |
1da177e4 | 101 | psi->pst = *pst; |
1da177e4 LT |
102 | |
103 | return psi; | |
104 | } | |
105 | ||
106 | int dm_register_path_selector(struct path_selector_type *pst) | |
107 | { | |
108 | int r = 0; | |
109 | struct ps_internal *psi = _alloc_path_selector(pst); | |
110 | ||
111 | if (!psi) | |
112 | return -ENOMEM; | |
113 | ||
114 | down_write(&_ps_lock); | |
115 | ||
116 | if (__find_path_selector_type(pst->name)) { | |
117 | kfree(psi); | |
118 | r = -EEXIST; | |
119 | } else | |
120 | list_add(&psi->list, &_path_selectors); | |
121 | ||
122 | up_write(&_ps_lock); | |
123 | ||
124 | return r; | |
125 | } | |
126 | ||
127 | int dm_unregister_path_selector(struct path_selector_type *pst) | |
128 | { | |
129 | struct ps_internal *psi; | |
130 | ||
131 | down_write(&_ps_lock); | |
132 | ||
133 | psi = __find_path_selector_type(pst->name); | |
134 | if (!psi) { | |
135 | up_write(&_ps_lock); | |
136 | return -EINVAL; | |
137 | } | |
138 | ||
139 | if (psi->use) { | |
140 | up_write(&_ps_lock); | |
141 | return -ETXTBSY; | |
142 | } | |
143 | ||
144 | list_del(&psi->list); | |
145 | ||
146 | up_write(&_ps_lock); | |
147 | ||
148 | kfree(psi); | |
149 | ||
150 | return 0; | |
151 | } | |
152 | ||
153 | EXPORT_SYMBOL_GPL(dm_register_path_selector); | |
154 | EXPORT_SYMBOL_GPL(dm_unregister_path_selector); |