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1 | /* |
2 | * Copyright (C) 2001-2002 Sistina Software (UK) Limited. |
3 | * Copyright (C) 2006-2008 Red Hat GmbH |
4 | * |
5 | * This file is released under the GPL. |
6 | */ |
7 | |
8 | #include "dm-exception-store.h" |
9 | |
10 | #include <linux/ctype.h> |
11 | #include <linux/mm.h> |
12 | #include <linux/pagemap.h> |
13 | #include <linux/vmalloc.h> |
14 | #include <linux/module.h> |
15 | #include <linux/slab.h> |
16 | |
17 | #define DM_MSG_PREFIX "snapshot exception stores" |
18 | |
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 | |
142 | static int set_chunk_size(struct dm_exception_store *store, |
143 | const char *chunk_size_arg, char **error) |
144 | { |
145 | unsigned chunk_size; |
146 | |
147 | if (kstrtouint(chunk_size_arg, 10, &chunk_size)) { |
148 | *error = "Invalid chunk size"; |
149 | return -EINVAL; |
150 | } |
151 | |
152 | if (!chunk_size) { |
153 | store->chunk_size = store->chunk_mask = store->chunk_shift = 0; |
154 | return 0; |
155 | } |
156 | |
157 | return dm_exception_store_set_chunk_size(store, chunk_size, error); |
158 | } |
159 | |
160 | int dm_exception_store_set_chunk_size(struct dm_exception_store *store, |
161 | unsigned chunk_size, |
162 | char **error) |
163 | { |
164 | /* Check chunk_size is a power of 2 */ |
165 | if (!is_power_of_2(chunk_size)) { |
166 | *error = "Chunk size is not a power of 2"; |
167 | return -EINVAL; |
168 | } |
169 | |
170 | /* Validate the chunk size against the device block size */ |
171 | if (chunk_size % |
172 | (bdev_logical_block_size(dm_snap_cow(store->snap)->bdev) >> 9) || |
173 | chunk_size % |
174 | (bdev_logical_block_size(dm_snap_origin(store->snap)->bdev) >> 9)) { |
175 | *error = "Chunk size is not a multiple of device blocksize"; |
176 | return -EINVAL; |
177 | } |
178 | |
179 | if (chunk_size > INT_MAX >> SECTOR_SHIFT) { |
180 | *error = "Chunk size is too high"; |
181 | return -EINVAL; |
182 | } |
183 | |
184 | store->chunk_size = chunk_size; |
185 | store->chunk_mask = chunk_size - 1; |
186 | store->chunk_shift = ffs(chunk_size) - 1; |
187 | |
188 | return 0; |
189 | } |
190 | |
191 | int dm_exception_store_create(struct dm_target *ti, int argc, char **argv, |
192 | struct dm_snapshot *snap, |
193 | unsigned *args_used, |
194 | struct dm_exception_store **store) |
195 | { |
196 | int r = 0; |
197 | struct dm_exception_store_type *type = NULL; |
198 | struct dm_exception_store *tmp_store; |
199 | char persistent; |
200 | |
201 | if (argc < 2) { |
202 | ti->error = "Insufficient exception store arguments"; |
203 | return -EINVAL; |
204 | } |
205 | |
206 | tmp_store = kmalloc(sizeof(*tmp_store), GFP_KERNEL); |
207 | if (!tmp_store) { |
208 | ti->error = "Exception store allocation failed"; |
209 | return -ENOMEM; |
210 | } |
211 | |
212 | persistent = toupper(*argv[0]); |
213 | if (persistent == 'P') |
214 | type = get_type("P"); |
215 | else if (persistent == 'N') |
216 | type = get_type("N"); |
217 | else { |
218 | ti->error = "Persistent flag is not P or N"; |
219 | r = -EINVAL; |
220 | goto bad_type; |
221 | } |
222 | |
223 | if (!type) { |
224 | ti->error = "Exception store type not recognised"; |
225 | r = -EINVAL; |
226 | goto bad_type; |
227 | } |
228 | |
229 | tmp_store->type = type; |
230 | tmp_store->snap = snap; |
231 | |
232 | r = set_chunk_size(tmp_store, argv[1], &ti->error); |
233 | if (r) |
234 | goto bad; |
235 | |
236 | r = type->ctr(tmp_store, 0, NULL); |
237 | if (r) { |
238 | ti->error = "Exception store type constructor failed"; |
239 | goto bad; |
240 | } |
241 | |
242 | *args_used = 2; |
243 | *store = tmp_store; |
244 | return 0; |
245 | |
246 | bad: |
247 | put_type(type); |
248 | bad_type: |
249 | kfree(tmp_store); |
250 | return r; |
251 | } |
252 | EXPORT_SYMBOL(dm_exception_store_create); |
253 | |
254 | void dm_exception_store_destroy(struct dm_exception_store *store) |
255 | { |
256 | store->type->dtr(store); |
257 | put_type(store->type); |
258 | kfree(store); |
259 | } |
260 | EXPORT_SYMBOL(dm_exception_store_destroy); |
261 | |
262 | int dm_exception_store_init(void) |
263 | { |
264 | int r; |
265 | |
266 | r = dm_transient_snapshot_init(); |
267 | if (r) { |
268 | DMERR("Unable to register transient exception store type."); |
269 | goto transient_fail; |
270 | } |
271 | |
272 | r = dm_persistent_snapshot_init(); |
273 | if (r) { |
274 | DMERR("Unable to register persistent exception store type"); |
275 | goto persistent_fail; |
276 | } |
277 | |
278 | return 0; |
279 | |
280 | persistent_fail: |
281 | dm_transient_snapshot_exit(); |
282 | transient_fail: |
283 | return r; |
284 | } |
285 | |
286 | void dm_exception_store_exit(void) |
287 | { |
288 | dm_persistent_snapshot_exit(); |
289 | dm_transient_snapshot_exit(); |
290 | } |
291 |
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