Commit | Line | Data |
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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 | 9 | |
fee1998e | 10 | #include <linux/ctype.h> |
1da177e4 LT |
11 | #include <linux/mm.h> |
12 | #include <linux/pagemap.h> | |
13 | #include <linux/vmalloc.h> | |
056075c7 | 14 | #include <linux/module.h> |
1da177e4 | 15 | #include <linux/slab.h> |
1da177e4 | 16 | |
4db6bfe0 | 17 | #define DM_MSG_PREFIX "snapshot exception stores" |
1da177e4 | 18 | |
493df71c JB |
19 | static LIST_HEAD(_exception_store_types); |
20 | static DEFINE_SPINLOCK(_lock); | |
21 | ||
22 | static struct dm_exception_store_type *__find_exception_store_type(const char *name) | |
23 | { | |
24 | struct dm_exception_store_type *type; | |
25 | ||
26 | list_for_each_entry(type, &_exception_store_types, list) | |
27 | if (!strcmp(name, type->name)) | |
28 | return type; | |
29 | ||
30 | return NULL; | |
31 | } | |
32 | ||
33 | static struct dm_exception_store_type *_get_exception_store_type(const char *name) | |
34 | { | |
35 | struct dm_exception_store_type *type; | |
36 | ||
37 | spin_lock(&_lock); | |
38 | ||
39 | type = __find_exception_store_type(name); | |
40 | ||
41 | if (type && !try_module_get(type->module)) | |
42 | type = NULL; | |
43 | ||
44 | spin_unlock(&_lock); | |
45 | ||
46 | return type; | |
47 | } | |
48 | ||
49 | /* | |
50 | * get_type | |
51 | * @type_name | |
52 | * | |
53 | * Attempt to retrieve the dm_exception_store_type by name. If not already | |
54 | * available, attempt to load the appropriate module. | |
55 | * | |
56 | * Exstore modules are named "dm-exstore-" followed by the 'type_name'. | |
57 | * Modules may contain multiple types. | |
58 | * This function will first try the module "dm-exstore-<type_name>", | |
59 | * then truncate 'type_name' on the last '-' and try again. | |
60 | * | |
61 | * For example, if type_name was "clustered-shared", it would search | |
62 | * 'dm-exstore-clustered-shared' then 'dm-exstore-clustered'. | |
63 | * | |
64 | * 'dm-exception-store-<type_name>' is too long of a name in my | |
65 | * opinion, which is why I've chosen to have the files | |
66 | * containing exception store implementations be 'dm-exstore-<type_name>'. | |
67 | * If you want your module to be autoloaded, you will follow this | |
68 | * naming convention. | |
69 | * | |
70 | * Returns: dm_exception_store_type* on success, NULL on failure | |
71 | */ | |
72 | static struct dm_exception_store_type *get_type(const char *type_name) | |
73 | { | |
74 | char *p, *type_name_dup; | |
75 | struct dm_exception_store_type *type; | |
76 | ||
77 | type = _get_exception_store_type(type_name); | |
78 | if (type) | |
79 | return type; | |
80 | ||
81 | type_name_dup = kstrdup(type_name, GFP_KERNEL); | |
82 | if (!type_name_dup) { | |
83 | DMERR("No memory left to attempt load for \"%s\"", type_name); | |
84 | return NULL; | |
85 | } | |
86 | ||
87 | while (request_module("dm-exstore-%s", type_name_dup) || | |
88 | !(type = _get_exception_store_type(type_name))) { | |
89 | p = strrchr(type_name_dup, '-'); | |
90 | if (!p) | |
91 | break; | |
92 | p[0] = '\0'; | |
93 | } | |
94 | ||
95 | if (!type) | |
96 | DMWARN("Module for exstore type \"%s\" not found.", type_name); | |
97 | ||
98 | kfree(type_name_dup); | |
99 | ||
100 | return type; | |
101 | } | |
102 | ||
103 | static void put_type(struct dm_exception_store_type *type) | |
104 | { | |
105 | spin_lock(&_lock); | |
106 | module_put(type->module); | |
107 | spin_unlock(&_lock); | |
108 | } | |
109 | ||
110 | int dm_exception_store_type_register(struct dm_exception_store_type *type) | |
111 | { | |
112 | int r = 0; | |
113 | ||
114 | spin_lock(&_lock); | |
115 | if (!__find_exception_store_type(type->name)) | |
116 | list_add(&type->list, &_exception_store_types); | |
117 | else | |
118 | r = -EEXIST; | |
119 | spin_unlock(&_lock); | |
120 | ||
121 | return r; | |
122 | } | |
123 | EXPORT_SYMBOL(dm_exception_store_type_register); | |
124 | ||
125 | int dm_exception_store_type_unregister(struct dm_exception_store_type *type) | |
126 | { | |
127 | spin_lock(&_lock); | |
128 | ||
129 | if (!__find_exception_store_type(type->name)) { | |
130 | spin_unlock(&_lock); | |
131 | return -EINVAL; | |
132 | } | |
133 | ||
134 | list_del(&type->list); | |
135 | ||
136 | spin_unlock(&_lock); | |
137 | ||
138 | return 0; | |
139 | } | |
140 | EXPORT_SYMBOL(dm_exception_store_type_unregister); | |
141 | ||
fee1998e JB |
142 | static int set_chunk_size(struct dm_exception_store *store, |
143 | const char *chunk_size_arg, char **error) | |
144 | { | |
145 | unsigned long chunk_size_ulong; | |
146 | char *value; | |
147 | ||
148 | chunk_size_ulong = simple_strtoul(chunk_size_arg, &value, 10); | |
df96eee6 MP |
149 | if (*chunk_size_arg == '\0' || *value != '\0' || |
150 | chunk_size_ulong > UINT_MAX) { | |
fee1998e JB |
151 | *error = "Invalid chunk size"; |
152 | return -EINVAL; | |
153 | } | |
154 | ||
155 | if (!chunk_size_ulong) { | |
156 | store->chunk_size = store->chunk_mask = store->chunk_shift = 0; | |
157 | return 0; | |
158 | } | |
159 | ||
df96eee6 MP |
160 | return dm_exception_store_set_chunk_size(store, |
161 | (unsigned) chunk_size_ulong, | |
2defcc3f MP |
162 | error); |
163 | } | |
164 | ||
165 | int dm_exception_store_set_chunk_size(struct dm_exception_store *store, | |
df96eee6 | 166 | unsigned chunk_size, |
2defcc3f MP |
167 | char **error) |
168 | { | |
fee1998e | 169 | /* Check chunk_size is a power of 2 */ |
df96eee6 | 170 | if (!is_power_of_2(chunk_size)) { |
fee1998e JB |
171 | *error = "Chunk size is not a power of 2"; |
172 | return -EINVAL; | |
173 | } | |
174 | ||
175 | /* Validate the chunk size against the device block size */ | |
fc56f6fb | 176 | if (chunk_size % |
c2411045 MP |
177 | (bdev_logical_block_size(dm_snap_cow(store->snap)->bdev) >> 9) || |
178 | chunk_size % | |
179 | (bdev_logical_block_size(dm_snap_origin(store->snap)->bdev) >> 9)) { | |
fee1998e JB |
180 | *error = "Chunk size is not a multiple of device blocksize"; |
181 | return -EINVAL; | |
182 | } | |
183 | ||
df96eee6 | 184 | if (chunk_size > INT_MAX >> SECTOR_SHIFT) { |
ae0b7448 MP |
185 | *error = "Chunk size is too high"; |
186 | return -EINVAL; | |
187 | } | |
188 | ||
df96eee6 MP |
189 | store->chunk_size = chunk_size; |
190 | store->chunk_mask = chunk_size - 1; | |
191 | store->chunk_shift = ffs(chunk_size) - 1; | |
fee1998e JB |
192 | |
193 | return 0; | |
194 | } | |
195 | ||
196 | int dm_exception_store_create(struct dm_target *ti, int argc, char **argv, | |
fc56f6fb | 197 | struct dm_snapshot *snap, |
fee1998e | 198 | unsigned *args_used, |
493df71c JB |
199 | struct dm_exception_store **store) |
200 | { | |
201 | int r = 0; | |
874d2f61 | 202 | struct dm_exception_store_type *type = NULL; |
493df71c | 203 | struct dm_exception_store *tmp_store; |
fee1998e JB |
204 | char persistent; |
205 | ||
fc56f6fb | 206 | if (argc < 2) { |
fee1998e JB |
207 | ti->error = "Insufficient exception store arguments"; |
208 | return -EINVAL; | |
209 | } | |
493df71c JB |
210 | |
211 | tmp_store = kmalloc(sizeof(*tmp_store), GFP_KERNEL); | |
fee1998e JB |
212 | if (!tmp_store) { |
213 | ti->error = "Exception store allocation failed"; | |
493df71c | 214 | return -ENOMEM; |
fee1998e | 215 | } |
493df71c | 216 | |
fc56f6fb | 217 | persistent = toupper(*argv[0]); |
874d2f61 MB |
218 | if (persistent == 'P') |
219 | type = get_type("P"); | |
220 | else if (persistent == 'N') | |
221 | type = get_type("N"); | |
222 | else { | |
fee1998e | 223 | ti->error = "Persistent flag is not P or N"; |
613978f8 JL |
224 | r = -EINVAL; |
225 | goto bad_type; | |
493df71c JB |
226 | } |
227 | ||
fee1998e JB |
228 | if (!type) { |
229 | ti->error = "Exception store type not recognised"; | |
230 | r = -EINVAL; | |
231 | goto bad_type; | |
232 | } | |
233 | ||
493df71c | 234 | tmp_store->type = type; |
fc56f6fb | 235 | tmp_store->snap = snap; |
493df71c | 236 | |
fc56f6fb | 237 | r = set_chunk_size(tmp_store, argv[1], &ti->error); |
fee1998e | 238 | if (r) |
fc56f6fb | 239 | goto bad; |
49beb2b8 | 240 | |
493df71c JB |
241 | r = type->ctr(tmp_store, 0, NULL); |
242 | if (r) { | |
fee1998e | 243 | ti->error = "Exception store type constructor failed"; |
fc56f6fb | 244 | goto bad; |
493df71c JB |
245 | } |
246 | ||
fc56f6fb | 247 | *args_used = 2; |
493df71c JB |
248 | *store = tmp_store; |
249 | return 0; | |
fee1998e | 250 | |
fc56f6fb | 251 | bad: |
fee1998e JB |
252 | put_type(type); |
253 | bad_type: | |
254 | kfree(tmp_store); | |
255 | return r; | |
493df71c JB |
256 | } |
257 | EXPORT_SYMBOL(dm_exception_store_create); | |
258 | ||
259 | void dm_exception_store_destroy(struct dm_exception_store *store) | |
260 | { | |
261 | store->type->dtr(store); | |
262 | put_type(store->type); | |
263 | kfree(store); | |
264 | } | |
265 | EXPORT_SYMBOL(dm_exception_store_destroy); | |
266 | ||
4db6bfe0 | 267 | int dm_exception_store_init(void) |
1da177e4 LT |
268 | { |
269 | int r; | |
1da177e4 | 270 | |
4db6bfe0 AK |
271 | r = dm_transient_snapshot_init(); |
272 | if (r) { | |
273 | DMERR("Unable to register transient exception store type."); | |
274 | goto transient_fail; | |
1da177e4 LT |
275 | } |
276 | ||
4db6bfe0 AK |
277 | r = dm_persistent_snapshot_init(); |
278 | if (r) { | |
279 | DMERR("Unable to register persistent exception store type"); | |
280 | goto persistent_fail; | |
1da177e4 LT |
281 | } |
282 | ||
283 | return 0; | |
1da177e4 | 284 | |
4db6bfe0 AK |
285 | persistent_fail: |
286 | dm_persistent_snapshot_exit(); | |
287 | transient_fail: | |
288 | return r; | |
1da177e4 LT |
289 | } |
290 | ||
4db6bfe0 | 291 | void dm_exception_store_exit(void) |
1da177e4 | 292 | { |
4db6bfe0 AK |
293 | dm_persistent_snapshot_exit(); |
294 | dm_transient_snapshot_exit(); | |
1da177e4 | 295 | } |