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1// SPDX-License-Identifier: GPL-2.0-only
2/*
3 * Copyright (C) 2012 Red Hat. All rights reserved.
4 *
5 * This file is released under the GPL.
6 */
7
8#include "dm-cache-policy-internal.h"
9#include "dm.h"
10
11#include <linux/module.h>
12#include <linux/slab.h>
13
14/*----------------------------------------------------------------*/
15
16#define DM_MSG_PREFIX "cache-policy"
17
18static DEFINE_SPINLOCK(register_lock);
19static LIST_HEAD(register_list);
20
21static struct dm_cache_policy_type *__find_policy(const char *name)
22{
23 struct dm_cache_policy_type *t;
24
25 list_for_each_entry(t, &register_list, list)
26 if (!strcmp(t->name, name))
27 return t;
28
29 return NULL;
30}
31
32static struct dm_cache_policy_type *__get_policy_once(const char *name)
33{
34 struct dm_cache_policy_type *t = __find_policy(name);
35
36 if (t && !try_module_get(t->owner)) {
37 DMWARN("couldn't get module %s", name);
38 t = ERR_PTR(-EINVAL);
39 }
40
41 return t;
42}
43
44static struct dm_cache_policy_type *get_policy_once(const char *name)
45{
46 struct dm_cache_policy_type *t;
47
48 spin_lock(&register_lock);
49 t = __get_policy_once(name);
50 spin_unlock(&register_lock);
51
52 return t;
53}
54
55static struct dm_cache_policy_type *get_policy(const char *name)
56{
57 struct dm_cache_policy_type *t;
58
59 t = get_policy_once(name);
60 if (IS_ERR(t))
61 return NULL;
62
63 if (t)
64 return t;
65
66 request_module("dm-cache-%s", name);
67
68 t = get_policy_once(name);
69 if (IS_ERR(t))
70 return NULL;
71
72 return t;
73}
74
75static void put_policy(struct dm_cache_policy_type *t)
76{
77 module_put(t->owner);
78}
79
80int dm_cache_policy_register(struct dm_cache_policy_type *type)
81{
82 int r;
83
84 /* One size fits all for now */
85 if (type->hint_size != 0 && type->hint_size != 4) {
86 DMWARN("hint size must be 0 or 4 but %llu supplied.", (unsigned long long) type->hint_size);
87 return -EINVAL;
88 }
89
90 spin_lock(&register_lock);
91 if (__find_policy(type->name)) {
92 DMWARN("attempt to register policy under duplicate name %s", type->name);
93 r = -EINVAL;
94 } else {
95 list_add(&type->list, &register_list);
96 r = 0;
97 }
98 spin_unlock(&register_lock);
99
100 return r;
101}
102EXPORT_SYMBOL_GPL(dm_cache_policy_register);
103
104void dm_cache_policy_unregister(struct dm_cache_policy_type *type)
105{
106 spin_lock(&register_lock);
107 list_del_init(&type->list);
108 spin_unlock(&register_lock);
109}
110EXPORT_SYMBOL_GPL(dm_cache_policy_unregister);
111
112struct dm_cache_policy *dm_cache_policy_create(const char *name,
113 dm_cblock_t cache_size,
114 sector_t origin_size,
115 sector_t cache_block_size)
116{
117 struct dm_cache_policy *p = NULL;
118 struct dm_cache_policy_type *type;
119
120 type = get_policy(name);
121 if (!type) {
122 DMWARN("unknown policy type");
123 return ERR_PTR(-EINVAL);
124 }
125
126 p = type->create(cache_size, origin_size, cache_block_size);
127 if (!p) {
128 put_policy(type);
129 return ERR_PTR(-ENOMEM);
130 }
131 p->private = type;
132
133 return p;
134}
135EXPORT_SYMBOL_GPL(dm_cache_policy_create);
136
137void dm_cache_policy_destroy(struct dm_cache_policy *p)
138{
139 struct dm_cache_policy_type *t = p->private;
140
141 p->destroy(p);
142 put_policy(t);
143}
144EXPORT_SYMBOL_GPL(dm_cache_policy_destroy);
145
146const char *dm_cache_policy_get_name(struct dm_cache_policy *p)
147{
148 struct dm_cache_policy_type *t = p->private;
149
150 /* if t->real is set then an alias was used (e.g. "default") */
151 if (t->real)
152 return t->real->name;
153
154 return t->name;
155}
156EXPORT_SYMBOL_GPL(dm_cache_policy_get_name);
157
158const unsigned int *dm_cache_policy_get_version(struct dm_cache_policy *p)
159{
160 struct dm_cache_policy_type *t = p->private;
161
162 return t->version;
163}
164EXPORT_SYMBOL_GPL(dm_cache_policy_get_version);
165
166size_t dm_cache_policy_get_hint_size(struct dm_cache_policy *p)
167{
168 struct dm_cache_policy_type *t = p->private;
169
170 return t->hint_size;
171}
172EXPORT_SYMBOL_GPL(dm_cache_policy_get_hint_size);
173
174/*----------------------------------------------------------------*/