2 * Copyright (C) 2001-2002 Sistina Software (UK) Limited.
3 * Copyright (C) 2006-2008 Red Hat GmbH
5 * This file is released under the GPL.
8 #include "dm-exception-store.h"
10 #include <linux/ctype.h>
12 #include <linux/pagemap.h>
13 #include <linux/vmalloc.h>
14 #include <linux/slab.h>
16 #define DM_MSG_PREFIX "snapshot exception stores"
18 static LIST_HEAD(_exception_store_types);
19 static DEFINE_SPINLOCK(_lock);
21 static struct dm_exception_store_type *__find_exception_store_type(const char *name)
23 struct dm_exception_store_type *type;
25 list_for_each_entry(type, &_exception_store_types, list)
26 if (!strcmp(name, type->name))
32 static struct dm_exception_store_type *_get_exception_store_type(const char *name)
34 struct dm_exception_store_type *type;
38 type = __find_exception_store_type(name);
40 if (type && !try_module_get(type->module))
52 * Attempt to retrieve the dm_exception_store_type by name. If not already
53 * available, attempt to load the appropriate module.
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.
60 * For example, if type_name was "clustered-shared", it would search
61 * 'dm-exstore-clustered-shared' then 'dm-exstore-clustered'.
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
69 * Returns: dm_exception_store_type* on success, NULL on failure
71 static struct dm_exception_store_type *get_type(const char *type_name)
73 char *p, *type_name_dup;
74 struct dm_exception_store_type *type;
76 type = _get_exception_store_type(type_name);
80 type_name_dup = kstrdup(type_name, GFP_KERNEL);
82 DMERR("No memory left to attempt load for \"%s\"", type_name);
86 while (request_module("dm-exstore-%s", type_name_dup) ||
87 !(type = _get_exception_store_type(type_name))) {
88 p = strrchr(type_name_dup, '-');
95 DMWARN("Module for exstore type \"%s\" not found.", type_name);
102 static void put_type(struct dm_exception_store_type *type)
105 module_put(type->module);
109 int dm_exception_store_type_register(struct dm_exception_store_type *type)
114 if (!__find_exception_store_type(type->name))
115 list_add(&type->list, &_exception_store_types);
122 EXPORT_SYMBOL(dm_exception_store_type_register);
124 int dm_exception_store_type_unregister(struct dm_exception_store_type *type)
128 if (!__find_exception_store_type(type->name)) {
133 list_del(&type->list);
139 EXPORT_SYMBOL(dm_exception_store_type_unregister);
141 static int set_chunk_size(struct dm_exception_store *store,
142 const char *chunk_size_arg, char **error)
144 unsigned long chunk_size_ulong;
147 chunk_size_ulong = simple_strtoul(chunk_size_arg, &value, 10);
148 if (*chunk_size_arg == '\0' || *value != '\0' ||
149 chunk_size_ulong > UINT_MAX) {
150 *error = "Invalid chunk size";
154 if (!chunk_size_ulong) {
155 store->chunk_size = store->chunk_mask = store->chunk_shift = 0;
159 return dm_exception_store_set_chunk_size(store,
160 (unsigned) chunk_size_ulong,
164 int dm_exception_store_set_chunk_size(struct dm_exception_store *store,
168 /* Check chunk_size is a power of 2 */
169 if (!is_power_of_2(chunk_size)) {
170 *error = "Chunk size is not a power of 2";
174 /* Validate the chunk size against the device block size */
175 if (chunk_size % (bdev_logical_block_size(store->cow->bdev) >> 9)) {
176 *error = "Chunk size is not a multiple of device blocksize";
180 if (chunk_size > INT_MAX >> SECTOR_SHIFT) {
181 *error = "Chunk size is too high";
185 store->chunk_size = chunk_size;
186 store->chunk_mask = chunk_size - 1;
187 store->chunk_shift = ffs(chunk_size) - 1;
192 int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
194 struct dm_exception_store **store)
197 struct dm_exception_store_type *type = NULL;
198 struct dm_exception_store *tmp_store;
202 ti->error = "Insufficient exception store arguments";
206 tmp_store = kmalloc(sizeof(*tmp_store), GFP_KERNEL);
208 ti->error = "Exception store allocation failed";
212 persistent = toupper(*argv[1]);
213 if (persistent == 'P')
214 type = get_type("P");
215 else if (persistent == 'N')
216 type = get_type("N");
218 ti->error = "Persistent flag is not P or N";
223 ti->error = "Exception store type not recognised";
228 tmp_store->type = type;
231 r = dm_get_device(ti, argv[0], 0, 0,
232 FMODE_READ | FMODE_WRITE, &tmp_store->cow);
234 ti->error = "Cannot get COW device";
238 r = set_chunk_size(tmp_store, argv[2], &ti->error);
242 r = type->ctr(tmp_store, 0, NULL);
244 ti->error = "Exception store type constructor failed";
253 dm_put_device(ti, tmp_store->cow);
260 EXPORT_SYMBOL(dm_exception_store_create);
262 void dm_exception_store_destroy(struct dm_exception_store *store)
264 store->type->dtr(store);
265 dm_put_device(store->ti, store->cow);
266 put_type(store->type);
269 EXPORT_SYMBOL(dm_exception_store_destroy);
271 int dm_exception_store_init(void)
275 r = dm_transient_snapshot_init();
277 DMERR("Unable to register transient exception store type.");
281 r = dm_persistent_snapshot_init();
283 DMERR("Unable to register persistent exception store type");
284 goto persistent_fail;
290 dm_persistent_snapshot_exit();
295 void dm_exception_store_exit(void)
297 dm_persistent_snapshot_exit();
298 dm_transient_snapshot_exit();