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1da177e4 | 1 | /* |
1da177e4 | 2 | * Copyright (C) 2001-2002 Sistina Software (UK) Limited. |
4db6bfe0 | 3 | * Copyright (C) 2006-2008 Red Hat GmbH |
1da177e4 LT |
4 | * |
5 | * This file is released under the GPL. | |
6 | */ | |
7 | ||
aea53d92 | 8 | #include "dm-exception-store.h" |
1da177e4 LT |
9 | |
10 | #include <linux/mm.h> | |
11 | #include <linux/pagemap.h> | |
12 | #include <linux/vmalloc.h> | |
13 | #include <linux/slab.h> | |
1da177e4 | 14 | |
4db6bfe0 | 15 | #define DM_MSG_PREFIX "snapshot exception stores" |
1da177e4 | 16 | |
493df71c JB |
17 | static LIST_HEAD(_exception_store_types); |
18 | static DEFINE_SPINLOCK(_lock); | |
19 | ||
20 | static struct dm_exception_store_type *__find_exception_store_type(const char *name) | |
21 | { | |
22 | struct dm_exception_store_type *type; | |
23 | ||
24 | list_for_each_entry(type, &_exception_store_types, list) | |
25 | if (!strcmp(name, type->name)) | |
26 | return type; | |
27 | ||
28 | return NULL; | |
29 | } | |
30 | ||
31 | static struct dm_exception_store_type *_get_exception_store_type(const char *name) | |
32 | { | |
33 | struct dm_exception_store_type *type; | |
34 | ||
35 | spin_lock(&_lock); | |
36 | ||
37 | type = __find_exception_store_type(name); | |
38 | ||
39 | if (type && !try_module_get(type->module)) | |
40 | type = NULL; | |
41 | ||
42 | spin_unlock(&_lock); | |
43 | ||
44 | return type; | |
45 | } | |
46 | ||
47 | /* | |
48 | * get_type | |
49 | * @type_name | |
50 | * | |
51 | * Attempt to retrieve the dm_exception_store_type by name. If not already | |
52 | * available, attempt to load the appropriate module. | |
53 | * | |
54 | * Exstore modules are named "dm-exstore-" followed by the 'type_name'. | |
55 | * Modules may contain multiple types. | |
56 | * This function will first try the module "dm-exstore-<type_name>", | |
57 | * then truncate 'type_name' on the last '-' and try again. | |
58 | * | |
59 | * For example, if type_name was "clustered-shared", it would search | |
60 | * 'dm-exstore-clustered-shared' then 'dm-exstore-clustered'. | |
61 | * | |
62 | * 'dm-exception-store-<type_name>' is too long of a name in my | |
63 | * opinion, which is why I've chosen to have the files | |
64 | * containing exception store implementations be 'dm-exstore-<type_name>'. | |
65 | * If you want your module to be autoloaded, you will follow this | |
66 | * naming convention. | |
67 | * | |
68 | * Returns: dm_exception_store_type* on success, NULL on failure | |
69 | */ | |
70 | static struct dm_exception_store_type *get_type(const char *type_name) | |
71 | { | |
72 | char *p, *type_name_dup; | |
73 | struct dm_exception_store_type *type; | |
74 | ||
75 | type = _get_exception_store_type(type_name); | |
76 | if (type) | |
77 | return type; | |
78 | ||
79 | type_name_dup = kstrdup(type_name, GFP_KERNEL); | |
80 | if (!type_name_dup) { | |
81 | DMERR("No memory left to attempt load for \"%s\"", type_name); | |
82 | return NULL; | |
83 | } | |
84 | ||
85 | while (request_module("dm-exstore-%s", type_name_dup) || | |
86 | !(type = _get_exception_store_type(type_name))) { | |
87 | p = strrchr(type_name_dup, '-'); | |
88 | if (!p) | |
89 | break; | |
90 | p[0] = '\0'; | |
91 | } | |
92 | ||
93 | if (!type) | |
94 | DMWARN("Module for exstore type \"%s\" not found.", type_name); | |
95 | ||
96 | kfree(type_name_dup); | |
97 | ||
98 | return type; | |
99 | } | |
100 | ||
101 | static void put_type(struct dm_exception_store_type *type) | |
102 | { | |
103 | spin_lock(&_lock); | |
104 | module_put(type->module); | |
105 | spin_unlock(&_lock); | |
106 | } | |
107 | ||
108 | int dm_exception_store_type_register(struct dm_exception_store_type *type) | |
109 | { | |
110 | int r = 0; | |
111 | ||
112 | spin_lock(&_lock); | |
113 | if (!__find_exception_store_type(type->name)) | |
114 | list_add(&type->list, &_exception_store_types); | |
115 | else | |
116 | r = -EEXIST; | |
117 | spin_unlock(&_lock); | |
118 | ||
119 | return r; | |
120 | } | |
121 | EXPORT_SYMBOL(dm_exception_store_type_register); | |
122 | ||
123 | int dm_exception_store_type_unregister(struct dm_exception_store_type *type) | |
124 | { | |
125 | spin_lock(&_lock); | |
126 | ||
127 | if (!__find_exception_store_type(type->name)) { | |
128 | spin_unlock(&_lock); | |
129 | return -EINVAL; | |
130 | } | |
131 | ||
132 | list_del(&type->list); | |
133 | ||
134 | spin_unlock(&_lock); | |
135 | ||
136 | return 0; | |
137 | } | |
138 | EXPORT_SYMBOL(dm_exception_store_type_unregister); | |
139 | ||
0cea9c78 | 140 | int dm_exception_store_create(const char *type_name, struct dm_target *ti, |
d0216849 JB |
141 | chunk_t chunk_size, chunk_t chunk_mask, |
142 | chunk_t chunk_shift, | |
493df71c JB |
143 | struct dm_exception_store **store) |
144 | { | |
145 | int r = 0; | |
146 | struct dm_exception_store_type *type; | |
147 | struct dm_exception_store *tmp_store; | |
148 | ||
149 | tmp_store = kmalloc(sizeof(*tmp_store), GFP_KERNEL); | |
150 | if (!tmp_store) | |
151 | return -ENOMEM; | |
152 | ||
153 | type = get_type(type_name); | |
154 | if (!type) { | |
155 | kfree(tmp_store); | |
156 | return -EINVAL; | |
157 | } | |
158 | ||
159 | tmp_store->type = type; | |
0cea9c78 | 160 | tmp_store->ti = ti; |
493df71c | 161 | |
d0216849 JB |
162 | tmp_store->chunk_size = chunk_size; |
163 | tmp_store->chunk_mask = chunk_mask; | |
164 | tmp_store->chunk_shift = chunk_shift; | |
165 | ||
493df71c JB |
166 | r = type->ctr(tmp_store, 0, NULL); |
167 | if (r) { | |
168 | put_type(type); | |
169 | kfree(tmp_store); | |
170 | return r; | |
171 | } | |
172 | ||
173 | *store = tmp_store; | |
174 | return 0; | |
175 | } | |
176 | EXPORT_SYMBOL(dm_exception_store_create); | |
177 | ||
178 | void dm_exception_store_destroy(struct dm_exception_store *store) | |
179 | { | |
180 | store->type->dtr(store); | |
181 | put_type(store->type); | |
182 | kfree(store); | |
183 | } | |
184 | EXPORT_SYMBOL(dm_exception_store_destroy); | |
185 | ||
4db6bfe0 | 186 | int dm_exception_store_init(void) |
1da177e4 LT |
187 | { |
188 | int r; | |
1da177e4 | 189 | |
4db6bfe0 AK |
190 | r = dm_transient_snapshot_init(); |
191 | if (r) { | |
192 | DMERR("Unable to register transient exception store type."); | |
193 | goto transient_fail; | |
1da177e4 LT |
194 | } |
195 | ||
4db6bfe0 AK |
196 | r = dm_persistent_snapshot_init(); |
197 | if (r) { | |
198 | DMERR("Unable to register persistent exception store type"); | |
199 | goto persistent_fail; | |
1da177e4 LT |
200 | } |
201 | ||
202 | return 0; | |
1da177e4 | 203 | |
4db6bfe0 AK |
204 | persistent_fail: |
205 | dm_persistent_snapshot_exit(); | |
206 | transient_fail: | |
207 | return r; | |
1da177e4 LT |
208 | } |
209 | ||
4db6bfe0 | 210 | void dm_exception_store_exit(void) |
1da177e4 | 211 | { |
4db6bfe0 AK |
212 | dm_persistent_snapshot_exit(); |
213 | dm_transient_snapshot_exit(); | |
1da177e4 | 214 | } |