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3bd94003 | 1 | // SPDX-License-Identifier: GPL-2.0-only |
1da177e4 LT |
2 | /* |
3 | * Copyright (C) 2003 Sistina Software. | |
4 | * Copyright (C) 2004 Red Hat, Inc. All rights reserved. | |
5 | * | |
6 | * Module Author: Heinz Mauelshagen | |
7 | * | |
8 | * This file is released under the GPL. | |
9 | * | |
10 | * Path selector registration. | |
11 | */ | |
12 | ||
586e80e6 | 13 | #include <linux/device-mapper.h> |
056075c7 | 14 | #include <linux/module.h> |
586e80e6 | 15 | |
1da177e4 LT |
16 | #include "dm-path-selector.h" |
17 | ||
18 | #include <linux/slab.h> | |
19 | ||
20 | struct ps_internal { | |
21 | struct path_selector_type pst; | |
1da177e4 | 22 | struct list_head list; |
1da177e4 LT |
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); | |
aea90588 JN |
48 | if (psi && !try_module_get(psi->pst.module)) |
49 | psi = NULL; | |
1da177e4 LT |
50 | up_read(&_ps_lock); |
51 | ||
52 | return psi; | |
53 | } | |
54 | ||
55 | struct path_selector_type *dm_get_path_selector(const char *name) | |
56 | { | |
57 | struct ps_internal *psi; | |
58 | ||
59 | if (!name) | |
60 | return NULL; | |
61 | ||
62 | psi = get_path_selector(name); | |
63 | if (!psi) { | |
64 | request_module("dm-%s", name); | |
65 | psi = get_path_selector(name); | |
66 | } | |
67 | ||
68 | return psi ? &psi->pst : NULL; | |
69 | } | |
70 | ||
71 | void dm_put_path_selector(struct path_selector_type *pst) | |
72 | { | |
73 | struct ps_internal *psi; | |
74 | ||
75 | if (!pst) | |
76 | return; | |
77 | ||
78 | down_read(&_ps_lock); | |
79 | psi = __find_path_selector_type(pst->name); | |
80 | if (!psi) | |
81 | goto out; | |
82 | ||
aea90588 | 83 | module_put(psi->pst.module); |
1da177e4 LT |
84 | out: |
85 | up_read(&_ps_lock); | |
86 | } | |
87 | ||
88 | static struct ps_internal *_alloc_path_selector(struct path_selector_type *pst) | |
89 | { | |
094262db | 90 | struct ps_internal *psi = kzalloc(sizeof(*psi), GFP_KERNEL); |
1da177e4 | 91 | |
094262db | 92 | if (psi) |
1da177e4 | 93 | psi->pst = *pst; |
1da177e4 LT |
94 | |
95 | return psi; | |
96 | } | |
97 | ||
98 | int dm_register_path_selector(struct path_selector_type *pst) | |
99 | { | |
100 | int r = 0; | |
101 | struct ps_internal *psi = _alloc_path_selector(pst); | |
102 | ||
103 | if (!psi) | |
104 | return -ENOMEM; | |
105 | ||
106 | down_write(&_ps_lock); | |
107 | ||
108 | if (__find_path_selector_type(pst->name)) { | |
109 | kfree(psi); | |
110 | r = -EEXIST; | |
111 | } else | |
112 | list_add(&psi->list, &_path_selectors); | |
113 | ||
114 | up_write(&_ps_lock); | |
115 | ||
116 | return r; | |
117 | } | |
aa07f9d8 | 118 | EXPORT_SYMBOL_GPL(dm_register_path_selector); |
1da177e4 LT |
119 | |
120 | int dm_unregister_path_selector(struct path_selector_type *pst) | |
121 | { | |
122 | struct ps_internal *psi; | |
123 | ||
124 | down_write(&_ps_lock); | |
125 | ||
126 | psi = __find_path_selector_type(pst->name); | |
127 | if (!psi) { | |
128 | up_write(&_ps_lock); | |
129 | return -EINVAL; | |
130 | } | |
131 | ||
1da177e4 LT |
132 | list_del(&psi->list); |
133 | ||
134 | up_write(&_ps_lock); | |
135 | ||
136 | kfree(psi); | |
137 | ||
138 | return 0; | |
139 | } | |
1da177e4 | 140 | EXPORT_SYMBOL_GPL(dm_unregister_path_selector); |