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);
142 * Round a number up to the nearest 'size' boundary. size must
145 static ulong round_up(ulong n, ulong size)
148 return (n + size) & ~size;
151 static int set_chunk_size(struct dm_exception_store *store,
152 const char *chunk_size_arg, char **error)
154 unsigned long chunk_size_ulong;
157 chunk_size_ulong = simple_strtoul(chunk_size_arg, &value, 10);
158 if (*chunk_size_arg == '\0' || *value != '\0' ||
159 chunk_size_ulong > UINT_MAX) {
160 *error = "Invalid chunk size";
164 if (!chunk_size_ulong) {
165 store->chunk_size = store->chunk_mask = store->chunk_shift = 0;
170 * Chunk size must be multiple of page size. Silently
171 * round up if it's not.
173 chunk_size_ulong = round_up(chunk_size_ulong, PAGE_SIZE >> 9);
175 return dm_exception_store_set_chunk_size(store,
176 (unsigned) chunk_size_ulong,
180 int dm_exception_store_set_chunk_size(struct dm_exception_store *store,
184 /* Check chunk_size is a power of 2 */
185 if (!is_power_of_2(chunk_size)) {
186 *error = "Chunk size is not a power of 2";
190 /* Validate the chunk size against the device block size */
191 if (chunk_size % (bdev_logical_block_size(store->cow->bdev) >> 9)) {
192 *error = "Chunk size is not a multiple of device blocksize";
196 if (chunk_size > INT_MAX >> SECTOR_SHIFT) {
197 *error = "Chunk size is too high";
201 store->chunk_size = chunk_size;
202 store->chunk_mask = chunk_size - 1;
203 store->chunk_shift = ffs(chunk_size) - 1;
208 int dm_exception_store_create(struct dm_target *ti, int argc, char **argv,
210 struct dm_exception_store **store)
213 struct dm_exception_store_type *type = NULL;
214 struct dm_exception_store *tmp_store;
218 ti->error = "Insufficient exception store arguments";
222 tmp_store = kmalloc(sizeof(*tmp_store), GFP_KERNEL);
224 ti->error = "Exception store allocation failed";
228 persistent = toupper(*argv[1]);
229 if (persistent == 'P')
230 type = get_type("P");
231 else if (persistent == 'N')
232 type = get_type("N");
234 ti->error = "Persistent flag is not P or N";
239 ti->error = "Exception store type not recognised";
244 tmp_store->type = type;
247 r = dm_get_device(ti, argv[0], 0, 0,
248 FMODE_READ | FMODE_WRITE, &tmp_store->cow);
250 ti->error = "Cannot get COW device";
254 r = set_chunk_size(tmp_store, argv[2], &ti->error);
258 r = type->ctr(tmp_store, 0, NULL);
260 ti->error = "Exception store type constructor failed";
269 dm_put_device(ti, tmp_store->cow);
276 EXPORT_SYMBOL(dm_exception_store_create);
278 void dm_exception_store_destroy(struct dm_exception_store *store)
280 store->type->dtr(store);
281 dm_put_device(store->ti, store->cow);
282 put_type(store->type);
285 EXPORT_SYMBOL(dm_exception_store_destroy);
287 int dm_exception_store_init(void)
291 r = dm_transient_snapshot_init();
293 DMERR("Unable to register transient exception store type.");
297 r = dm_persistent_snapshot_init();
299 DMERR("Unable to register persistent exception store type");
300 goto persistent_fail;
306 dm_persistent_snapshot_exit();
311 void dm_exception_store_exit(void)
313 dm_persistent_snapshot_exit();
314 dm_transient_snapshot_exit();