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138 lines · 2.5 KiB

1// SPDX-License-Identifier: GPL-2.0-only
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
13#include <linux/device-mapper.h>
14#include <linux/module.h>
15
16#include "dm-path-selector.h"
17
18#include <linux/slab.h>
19
20struct ps_internal {
21 struct path_selector_type pst;
22 struct list_head list;
23};
24
25#define pst_to_psi(__pst) container_of((__pst), struct ps_internal, pst)
26
27static LIST_HEAD(_path_selectors);
28static DECLARE_RWSEM(_ps_lock);
29
30static struct ps_internal *__find_path_selector_type(const char *name)
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
42static 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 && !try_module_get(psi->pst.module))
49 psi = NULL;
50 up_read(&_ps_lock);
51
52 return psi;
53}
54
55struct 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
71void 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
83 module_put(psi->pst.module);
84out:
85 up_read(&_ps_lock);
86}
87
88static struct ps_internal *_alloc_path_selector(struct path_selector_type *pst)
89{
90 struct ps_internal *psi = kzalloc_obj(*psi);
91
92 if (psi)
93 psi->pst = *pst;
94
95 return psi;
96}
97
98int 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 = -EBUSY;
111 } else
112 list_add(&psi->list, &_path_selectors);
113
114 up_write(&_ps_lock);
115
116 return r;
117}
118EXPORT_SYMBOL_GPL(dm_register_path_selector);
119
120void 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 (WARN_ON(!psi)) {
128 up_write(&_ps_lock);
129 return;
130 }
131
132 list_del(&psi->list);
133
134 up_write(&_ps_lock);
135
136 kfree(psi);
137}
138EXPORT_SYMBOL_GPL(dm_unregister_path_selector);