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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
18static LIST_HEAD(_exception_store_types);
19static DEFINE_SPINLOCK(_lock);
20
21static 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
32static 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 */
71static 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
102static 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
109int 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}
122EXPORT_SYMBOL(dm_exception_store_type_register);
123
124int 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}
139EXPORT_SYMBOL(dm_exception_store_type_unregister);
140
fee1998e
JB
141static int set_chunk_size(struct dm_exception_store *store,
142 const char *chunk_size_arg, char **error)
143{
144 unsigned long chunk_size_ulong;
145 char *value;
146
147 chunk_size_ulong = simple_strtoul(chunk_size_arg, &value, 10);
df96eee6
MP
148 if (*chunk_size_arg == '\0' || *value != '\0' ||
149 chunk_size_ulong > UINT_MAX) {
fee1998e
JB
150 *error = "Invalid chunk size";
151 return -EINVAL;
152 }
153
154 if (!chunk_size_ulong) {
155 store->chunk_size = store->chunk_mask = store->chunk_shift = 0;
156 return 0;
157 }
158
df96eee6
MP
159 return dm_exception_store_set_chunk_size(store,
160 (unsigned) chunk_size_ulong,
2defcc3f
MP
161 error);
162}
163
164int dm_exception_store_set_chunk_size(struct dm_exception_store *store,
df96eee6 165 unsigned chunk_size,
2defcc3f
MP
166 char **error)
167{
fee1998e 168 /* Check chunk_size is a power of 2 */
df96eee6 169 if (!is_power_of_2(chunk_size)) {
fee1998e
JB
170 *error = "Chunk size is not a power of 2";
171 return -EINVAL;
172 }
173
174 /* Validate the chunk size against the device block size */
df96eee6 175 if (chunk_size % (bdev_logical_block_size(store->cow->bdev) >> 9)) {
fee1998e
JB
176 *error = "Chunk size is not a multiple of device blocksize";
177 return -EINVAL;
178 }
179
df96eee6 180 if (chunk_size > INT_MAX >> SECTOR_SHIFT) {
ae0b7448
MP
181 *error = "Chunk size is too high";
182 return -EINVAL;
183 }
184
df96eee6
MP
185 store->chunk_size = chunk_size;
186 store->chunk_mask = chunk_size - 1;
187 store->chunk_shift = ffs(chunk_size) - 1;
fee1998e
JB
188
189 return 0;
190}
191
192int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
193 unsigned *args_used,
493df71c
JB
194 struct dm_exception_store **store)
195{
196 int r = 0;
874d2f61 197 struct dm_exception_store_type *type = NULL;
493df71c 198 struct dm_exception_store *tmp_store;
fee1998e
JB
199 char persistent;
200
201 if (argc < 3) {
202 ti->error = "Insufficient exception store arguments";
203 return -EINVAL;
204 }
493df71c
JB
205
206 tmp_store = kmalloc(sizeof(*tmp_store), GFP_KERNEL);
fee1998e
JB
207 if (!tmp_store) {
208 ti->error = "Exception store allocation failed";
493df71c 209 return -ENOMEM;
fee1998e 210 }
493df71c 211
fee1998e 212 persistent = toupper(*argv[1]);
874d2f61
MB
213 if (persistent == 'P')
214 type = get_type("P");
215 else if (persistent == 'N')
216 type = get_type("N");
217 else {
fee1998e 218 ti->error = "Persistent flag is not P or N";
493df71c
JB
219 return -EINVAL;
220 }
221
fee1998e
JB
222 if (!type) {
223 ti->error = "Exception store type not recognised";
224 r = -EINVAL;
225 goto bad_type;
226 }
227
493df71c 228 tmp_store->type = type;
0cea9c78 229 tmp_store->ti = ti;
493df71c 230
fee1998e
JB
231 r = dm_get_device(ti, argv[0], 0, 0,
232 FMODE_READ | FMODE_WRITE, &tmp_store->cow);
233 if (r) {
234 ti->error = "Cannot get COW device";
235 goto bad_cow;
236 }
d0216849 237
fee1998e
JB
238 r = set_chunk_size(tmp_store, argv[2], &ti->error);
239 if (r)
0e8c4e4e 240 goto bad_ctr;
49beb2b8 241
493df71c
JB
242 r = type->ctr(tmp_store, 0, NULL);
243 if (r) {
fee1998e
JB
244 ti->error = "Exception store type constructor failed";
245 goto bad_ctr;
493df71c
JB
246 }
247
fee1998e 248 *args_used = 3;
493df71c
JB
249 *store = tmp_store;
250 return 0;
fee1998e
JB
251
252bad_ctr:
253 dm_put_device(ti, tmp_store->cow);
254bad_cow:
255 put_type(type);
256bad_type:
257 kfree(tmp_store);
258 return r;
493df71c
JB
259}
260EXPORT_SYMBOL(dm_exception_store_create);
261
262void dm_exception_store_destroy(struct dm_exception_store *store)
263{
264 store->type->dtr(store);
fee1998e 265 dm_put_device(store->ti, store->cow);
493df71c
JB
266 put_type(store->type);
267 kfree(store);
268}
269EXPORT_SYMBOL(dm_exception_store_destroy);
270
4db6bfe0 271int dm_exception_store_init(void)
1da177e4
LT
272{
273 int r;
1da177e4 274
4db6bfe0
AK
275 r = dm_transient_snapshot_init();
276 if (r) {
277 DMERR("Unable to register transient exception store type.");
278 goto transient_fail;
1da177e4
LT
279 }
280
4db6bfe0
AK
281 r = dm_persistent_snapshot_init();
282 if (r) {
283 DMERR("Unable to register persistent exception store type");
284 goto persistent_fail;
1da177e4
LT
285 }
286
287 return 0;
1da177e4 288
4db6bfe0
AK
289persistent_fail:
290 dm_persistent_snapshot_exit();
291transient_fail:
292 return r;
1da177e4
LT
293}
294
4db6bfe0 295void dm_exception_store_exit(void)
1da177e4 296{
4db6bfe0
AK
297 dm_persistent_snapshot_exit();
298 dm_transient_snapshot_exit();
1da177e4 299}