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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> | |
14 | #include <linux/slab.h> | |
1da177e4 | 15 | |
4db6bfe0 | 16 | #define DM_MSG_PREFIX "snapshot exception stores" |
1da177e4 | 17 | |
493df71c JB |
18 | static LIST_HEAD(_exception_store_types); |
19 | static DEFINE_SPINLOCK(_lock); | |
20 | ||
21 | static struct dm_exception_store_type *__find_exception_store_type(const char *name) | |
22 | { | |
23 | struct dm_exception_store_type *type; | |
24 | ||
25 | list_for_each_entry(type, &_exception_store_types, list) | |
26 | if (!strcmp(name, type->name)) | |
27 | return type; | |
28 | ||
29 | return NULL; | |
30 | } | |
31 | ||
32 | static struct dm_exception_store_type *_get_exception_store_type(const char *name) | |
33 | { | |
34 | struct dm_exception_store_type *type; | |
35 | ||
36 | spin_lock(&_lock); | |
37 | ||
38 | type = __find_exception_store_type(name); | |
39 | ||
40 | if (type && !try_module_get(type->module)) | |
41 | type = NULL; | |
42 | ||
43 | spin_unlock(&_lock); | |
44 | ||
45 | return type; | |
46 | } | |
47 | ||
48 | /* | |
49 | * get_type | |
50 | * @type_name | |
51 | * | |
52 | * Attempt to retrieve the dm_exception_store_type by name. If not already | |
53 | * available, attempt to load the appropriate module. | |
54 | * | |
55 | * Exstore modules are named "dm-exstore-" followed by the 'type_name'. | |
56 | * Modules may contain multiple types. | |
57 | * This function will first try the module "dm-exstore-<type_name>", | |
58 | * then truncate 'type_name' on the last '-' and try again. | |
59 | * | |
60 | * For example, if type_name was "clustered-shared", it would search | |
61 | * 'dm-exstore-clustered-shared' then 'dm-exstore-clustered'. | |
62 | * | |
63 | * 'dm-exception-store-<type_name>' is too long of a name in my | |
64 | * opinion, which is why I've chosen to have the files | |
65 | * containing exception store implementations be 'dm-exstore-<type_name>'. | |
66 | * If you want your module to be autoloaded, you will follow this | |
67 | * naming convention. | |
68 | * | |
69 | * Returns: dm_exception_store_type* on success, NULL on failure | |
70 | */ | |
71 | static struct dm_exception_store_type *get_type(const char *type_name) | |
72 | { | |
73 | char *p, *type_name_dup; | |
74 | struct dm_exception_store_type *type; | |
75 | ||
76 | type = _get_exception_store_type(type_name); | |
77 | if (type) | |
78 | return type; | |
79 | ||
80 | type_name_dup = kstrdup(type_name, GFP_KERNEL); | |
81 | if (!type_name_dup) { | |
82 | DMERR("No memory left to attempt load for \"%s\"", type_name); | |
83 | return NULL; | |
84 | } | |
85 | ||
86 | while (request_module("dm-exstore-%s", type_name_dup) || | |
87 | !(type = _get_exception_store_type(type_name))) { | |
88 | p = strrchr(type_name_dup, '-'); | |
89 | if (!p) | |
90 | break; | |
91 | p[0] = '\0'; | |
92 | } | |
93 | ||
94 | if (!type) | |
95 | DMWARN("Module for exstore type \"%s\" not found.", type_name); | |
96 | ||
97 | kfree(type_name_dup); | |
98 | ||
99 | return type; | |
100 | } | |
101 | ||
102 | static void put_type(struct dm_exception_store_type *type) | |
103 | { | |
104 | spin_lock(&_lock); | |
105 | module_put(type->module); | |
106 | spin_unlock(&_lock); | |
107 | } | |
108 | ||
109 | int dm_exception_store_type_register(struct dm_exception_store_type *type) | |
110 | { | |
111 | int r = 0; | |
112 | ||
113 | spin_lock(&_lock); | |
114 | if (!__find_exception_store_type(type->name)) | |
115 | list_add(&type->list, &_exception_store_types); | |
116 | else | |
117 | r = -EEXIST; | |
118 | spin_unlock(&_lock); | |
119 | ||
120 | return r; | |
121 | } | |
122 | EXPORT_SYMBOL(dm_exception_store_type_register); | |
123 | ||
124 | int dm_exception_store_type_unregister(struct dm_exception_store_type *type) | |
125 | { | |
126 | spin_lock(&_lock); | |
127 | ||
128 | if (!__find_exception_store_type(type->name)) { | |
129 | spin_unlock(&_lock); | |
130 | return -EINVAL; | |
131 | } | |
132 | ||
133 | list_del(&type->list); | |
134 | ||
135 | spin_unlock(&_lock); | |
136 | ||
137 | return 0; | |
138 | } | |
139 | EXPORT_SYMBOL(dm_exception_store_type_unregister); | |
140 | ||
fee1998e JB |
141 | /* |
142 | * Round a number up to the nearest 'size' boundary. size must | |
143 | * be a power of 2. | |
144 | */ | |
145 | static ulong round_up(ulong n, ulong size) | |
146 | { | |
147 | size--; | |
148 | return (n + size) & ~size; | |
149 | } | |
150 | ||
151 | static int set_chunk_size(struct dm_exception_store *store, | |
152 | const char *chunk_size_arg, char **error) | |
153 | { | |
154 | unsigned long chunk_size_ulong; | |
155 | char *value; | |
156 | ||
157 | chunk_size_ulong = simple_strtoul(chunk_size_arg, &value, 10); | |
158 | if (*chunk_size_arg == '\0' || *value != '\0') { | |
159 | *error = "Invalid chunk size"; | |
160 | return -EINVAL; | |
161 | } | |
162 | ||
163 | if (!chunk_size_ulong) { | |
164 | store->chunk_size = store->chunk_mask = store->chunk_shift = 0; | |
165 | return 0; | |
166 | } | |
167 | ||
168 | /* | |
169 | * Chunk size must be multiple of page size. Silently | |
170 | * round up if it's not. | |
171 | */ | |
172 | chunk_size_ulong = round_up(chunk_size_ulong, PAGE_SIZE >> 9); | |
173 | ||
2defcc3f MP |
174 | return dm_exception_store_set_chunk_size(store, chunk_size_ulong, |
175 | error); | |
176 | } | |
177 | ||
178 | int dm_exception_store_set_chunk_size(struct dm_exception_store *store, | |
179 | unsigned long chunk_size_ulong, | |
180 | char **error) | |
181 | { | |
fee1998e JB |
182 | /* Check chunk_size is a power of 2 */ |
183 | if (!is_power_of_2(chunk_size_ulong)) { | |
184 | *error = "Chunk size is not a power of 2"; | |
185 | return -EINVAL; | |
186 | } | |
187 | ||
188 | /* Validate the chunk size against the device block size */ | |
e1defc4f | 189 | if (chunk_size_ulong % (bdev_logical_block_size(store->cow->bdev) >> 9)) { |
fee1998e JB |
190 | *error = "Chunk size is not a multiple of device blocksize"; |
191 | return -EINVAL; | |
192 | } | |
193 | ||
ae0b7448 MP |
194 | if (chunk_size_ulong > INT_MAX >> SECTOR_SHIFT) { |
195 | *error = "Chunk size is too high"; | |
196 | return -EINVAL; | |
197 | } | |
198 | ||
fee1998e JB |
199 | store->chunk_size = chunk_size_ulong; |
200 | store->chunk_mask = chunk_size_ulong - 1; | |
201 | store->chunk_shift = ffs(chunk_size_ulong) - 1; | |
202 | ||
203 | return 0; | |
204 | } | |
205 | ||
206 | int dm_exception_store_create(struct dm_target *ti, int argc, char **argv, | |
207 | unsigned *args_used, | |
493df71c JB |
208 | struct dm_exception_store **store) |
209 | { | |
210 | int r = 0; | |
874d2f61 | 211 | struct dm_exception_store_type *type = NULL; |
493df71c | 212 | struct dm_exception_store *tmp_store; |
fee1998e JB |
213 | char persistent; |
214 | ||
215 | if (argc < 3) { | |
216 | ti->error = "Insufficient exception store arguments"; | |
217 | return -EINVAL; | |
218 | } | |
493df71c JB |
219 | |
220 | tmp_store = kmalloc(sizeof(*tmp_store), GFP_KERNEL); | |
fee1998e JB |
221 | if (!tmp_store) { |
222 | ti->error = "Exception store allocation failed"; | |
493df71c | 223 | return -ENOMEM; |
fee1998e | 224 | } |
493df71c | 225 | |
fee1998e | 226 | persistent = toupper(*argv[1]); |
874d2f61 MB |
227 | if (persistent == 'P') |
228 | type = get_type("P"); | |
229 | else if (persistent == 'N') | |
230 | type = get_type("N"); | |
231 | else { | |
fee1998e | 232 | ti->error = "Persistent flag is not P or N"; |
493df71c JB |
233 | return -EINVAL; |
234 | } | |
235 | ||
fee1998e JB |
236 | if (!type) { |
237 | ti->error = "Exception store type not recognised"; | |
238 | r = -EINVAL; | |
239 | goto bad_type; | |
240 | } | |
241 | ||
493df71c | 242 | tmp_store->type = type; |
0cea9c78 | 243 | tmp_store->ti = ti; |
493df71c | 244 | |
fee1998e JB |
245 | r = dm_get_device(ti, argv[0], 0, 0, |
246 | FMODE_READ | FMODE_WRITE, &tmp_store->cow); | |
247 | if (r) { | |
248 | ti->error = "Cannot get COW device"; | |
249 | goto bad_cow; | |
250 | } | |
d0216849 | 251 | |
fee1998e JB |
252 | r = set_chunk_size(tmp_store, argv[2], &ti->error); |
253 | if (r) | |
0e8c4e4e | 254 | goto bad_ctr; |
49beb2b8 | 255 | |
493df71c JB |
256 | r = type->ctr(tmp_store, 0, NULL); |
257 | if (r) { | |
fee1998e JB |
258 | ti->error = "Exception store type constructor failed"; |
259 | goto bad_ctr; | |
493df71c JB |
260 | } |
261 | ||
fee1998e | 262 | *args_used = 3; |
493df71c JB |
263 | *store = tmp_store; |
264 | return 0; | |
fee1998e JB |
265 | |
266 | bad_ctr: | |
267 | dm_put_device(ti, tmp_store->cow); | |
268 | bad_cow: | |
269 | put_type(type); | |
270 | bad_type: | |
271 | kfree(tmp_store); | |
272 | return r; | |
493df71c JB |
273 | } |
274 | EXPORT_SYMBOL(dm_exception_store_create); | |
275 | ||
276 | void dm_exception_store_destroy(struct dm_exception_store *store) | |
277 | { | |
278 | store->type->dtr(store); | |
fee1998e | 279 | dm_put_device(store->ti, store->cow); |
493df71c JB |
280 | put_type(store->type); |
281 | kfree(store); | |
282 | } | |
283 | EXPORT_SYMBOL(dm_exception_store_destroy); | |
284 | ||
4db6bfe0 | 285 | int dm_exception_store_init(void) |
1da177e4 LT |
286 | { |
287 | int r; | |
1da177e4 | 288 | |
4db6bfe0 AK |
289 | r = dm_transient_snapshot_init(); |
290 | if (r) { | |
291 | DMERR("Unable to register transient exception store type."); | |
292 | goto transient_fail; | |
1da177e4 LT |
293 | } |
294 | ||
4db6bfe0 AK |
295 | r = dm_persistent_snapshot_init(); |
296 | if (r) { | |
297 | DMERR("Unable to register persistent exception store type"); | |
298 | goto persistent_fail; | |
1da177e4 LT |
299 | } |
300 | ||
301 | return 0; | |
1da177e4 | 302 | |
4db6bfe0 AK |
303 | persistent_fail: |
304 | dm_persistent_snapshot_exit(); | |
305 | transient_fail: | |
306 | return r; | |
1da177e4 LT |
307 | } |
308 | ||
4db6bfe0 | 309 | void dm_exception_store_exit(void) |
1da177e4 | 310 | { |
4db6bfe0 AK |
311 | dm_persistent_snapshot_exit(); |
312 | dm_transient_snapshot_exit(); | |
1da177e4 | 313 | } |