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1 | /* |
2 | * Copyright (C) 2012 Red Hat. All rights reserved. |
3 | * |
4 | * This file is released under the GPL. |
5 | */ |
6 | |
7 | #include "dm-cache-policy-internal.h" |
8 | #include "dm.h" |
9 | |
10 | #include <linux/module.h> |
11 | #include <linux/slab.h> |
12 | |
13 | /*----------------------------------------------------------------*/ |
14 | |
15 | #define DM_MSG_PREFIX "cache-policy" |
16 | |
17 | static DEFINE_SPINLOCK(register_lock); |
18 | static LIST_HEAD(register_list); |
19 | |
20 | static struct dm_cache_policy_type *__find_policy(const char *name) |
21 | { |
22 | struct dm_cache_policy_type *t; |
23 | |
24 | list_for_each_entry(t, ®ister_list, list) |
25 | if (!strcmp(t->name, name)) |
26 | return t; |
27 | |
28 | return NULL; |
29 | } |
30 | |
31 | static struct dm_cache_policy_type *__get_policy_once(const char *name) |
32 | { |
33 | struct dm_cache_policy_type *t = __find_policy(name); |
34 | |
35 | if (t && !try_module_get(t->owner)) { |
36 | DMWARN("couldn't get module %s", name); |
37 | t = ERR_PTR(-EINVAL); |
38 | } |
39 | |
40 | return t; |
41 | } |
42 | |
43 | static struct dm_cache_policy_type *get_policy_once(const char *name) |
44 | { |
45 | struct dm_cache_policy_type *t; |
46 | |
47 | spin_lock(®ister_lock); |
48 | t = __get_policy_once(name); |
49 | spin_unlock(®ister_lock); |
50 | |
51 | return t; |
52 | } |
53 | |
54 | static struct dm_cache_policy_type *get_policy(const char *name) |
55 | { |
56 | struct dm_cache_policy_type *t; |
57 | |
58 | t = get_policy_once(name); |
59 | if (IS_ERR(t)) |
60 | return NULL; |
61 | |
62 | if (t) |
63 | return t; |
64 | |
65 | request_module("dm-cache-%s", name); |
66 | |
67 | t = get_policy_once(name); |
68 | if (IS_ERR(t)) |
69 | return NULL; |
70 | |
71 | return t; |
72 | } |
73 | |
74 | static void put_policy(struct dm_cache_policy_type *t) |
75 | { |
76 | module_put(t->owner); |
77 | } |
78 | |
79 | int dm_cache_policy_register(struct dm_cache_policy_type *type) |
80 | { |
81 | int r; |
82 | |
83 | /* One size fits all for now */ |
84 | if (type->hint_size != 0 && type->hint_size != 4) { |
85 | DMWARN("hint size must be 0 or 4 but %llu supplied.", (unsigned long long) type->hint_size); |
86 | return -EINVAL; |
87 | } |
88 | |
89 | spin_lock(®ister_lock); |
90 | if (__find_policy(type->name)) { |
91 | DMWARN("attempt to register policy under duplicate name %s", type->name); |
92 | r = -EINVAL; |
93 | } else { |
94 | list_add(&type->list, ®ister_list); |
95 | r = 0; |
96 | } |
97 | spin_unlock(®ister_lock); |
98 | |
99 | return r; |
100 | } |
101 | EXPORT_SYMBOL_GPL(dm_cache_policy_register); |
102 | |
103 | void dm_cache_policy_unregister(struct dm_cache_policy_type *type) |
104 | { |
105 | spin_lock(®ister_lock); |
106 | list_del_init(&type->list); |
107 | spin_unlock(®ister_lock); |
108 | } |
109 | EXPORT_SYMBOL_GPL(dm_cache_policy_unregister); |
110 | |
111 | struct dm_cache_policy *dm_cache_policy_create(const char *name, |
112 | dm_cblock_t cache_size, |
113 | sector_t origin_size, |
114 | sector_t cache_block_size) |
115 | { |
116 | struct dm_cache_policy *p = NULL; |
117 | struct dm_cache_policy_type *type; |
118 | |
119 | type = get_policy(name); |
120 | if (!type) { |
121 | DMWARN("unknown policy type"); |
122 | return NULL; |
123 | } |
124 | |
125 | p = type->create(cache_size, origin_size, cache_block_size); |
126 | if (!p) { |
127 | put_policy(type); |
128 | return NULL; |
129 | } |
130 | p->private = type; |
131 | |
132 | return p; |
133 | } |
134 | EXPORT_SYMBOL_GPL(dm_cache_policy_create); |
135 | |
136 | void dm_cache_policy_destroy(struct dm_cache_policy *p) |
137 | { |
138 | struct dm_cache_policy_type *t = p->private; |
139 | |
140 | p->destroy(p); |
141 | put_policy(t); |
142 | } |
143 | EXPORT_SYMBOL_GPL(dm_cache_policy_destroy); |
144 | |
145 | const char *dm_cache_policy_get_name(struct dm_cache_policy *p) |
146 | { |
147 | struct dm_cache_policy_type *t = p->private; |
148 | |
149 | return t->name; |
150 | } |
151 | EXPORT_SYMBOL_GPL(dm_cache_policy_get_name); |
152 | |
153 | const unsigned *dm_cache_policy_get_version(struct dm_cache_policy *p) |
154 | { |
155 | struct dm_cache_policy_type *t = p->private; |
156 | |
157 | return t->version; |
158 | } |
159 | EXPORT_SYMBOL_GPL(dm_cache_policy_get_version); |
160 | |
161 | size_t dm_cache_policy_get_hint_size(struct dm_cache_policy *p) |
162 | { |
163 | struct dm_cache_policy_type *t = p->private; |
164 | |
165 | return t->hint_size; |
166 | } |
167 | EXPORT_SYMBOL_GPL(dm_cache_policy_get_hint_size); |
168 | |
169 | /*----------------------------------------------------------------*/ |
170 |
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