| 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/slab.h> |
| 15 | |
| 16 | #define DM_MSG_PREFIX "snapshot exception stores" |
| 17 | |
| 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 | |
| 141 | static 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); |
| 148 | if (*chunk_size_arg == '\0' || *value != '\0' || |
| 149 | chunk_size_ulong > UINT_MAX) { |
| 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 | |
| 159 | return dm_exception_store_set_chunk_size(store, |
| 160 | (unsigned) chunk_size_ulong, |
| 161 | error); |
| 162 | } |
| 163 | |
| 164 | int dm_exception_store_set_chunk_size(struct dm_exception_store *store, |
| 165 | unsigned chunk_size, |
| 166 | char **error) |
| 167 | { |
| 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"; |
| 171 | return -EINVAL; |
| 172 | } |
| 173 | |
| 174 | /* Validate the chunk size against the device block size */ |
| 175 | if (chunk_size % |
| 176 | (bdev_logical_block_size(dm_snap_cow(store->snap)->bdev) >> 9) || |
| 177 | chunk_size % |
| 178 | (bdev_logical_block_size(dm_snap_origin(store->snap)->bdev) >> 9)) { |
| 179 | *error = "Chunk size is not a multiple of device blocksize"; |
| 180 | return -EINVAL; |
| 181 | } |
| 182 | |
| 183 | if (chunk_size > INT_MAX >> SECTOR_SHIFT) { |
| 184 | *error = "Chunk size is too high"; |
| 185 | return -EINVAL; |
| 186 | } |
| 187 | |
| 188 | store->chunk_size = chunk_size; |
| 189 | store->chunk_mask = chunk_size - 1; |
| 190 | store->chunk_shift = ffs(chunk_size) - 1; |
| 191 | |
| 192 | return 0; |
| 193 | } |
| 194 | |
| 195 | int dm_exception_store_create(struct dm_target *ti, int argc, char **argv, |
| 196 | struct dm_snapshot *snap, |
| 197 | unsigned *args_used, |
| 198 | struct dm_exception_store **store) |
| 199 | { |
| 200 | int r = 0; |
| 201 | struct dm_exception_store_type *type = NULL; |
| 202 | struct dm_exception_store *tmp_store; |
| 203 | char persistent; |
| 204 | |
| 205 | if (argc < 2) { |
| 206 | ti->error = "Insufficient exception store arguments"; |
| 207 | return -EINVAL; |
| 208 | } |
| 209 | |
| 210 | tmp_store = kmalloc(sizeof(*tmp_store), GFP_KERNEL); |
| 211 | if (!tmp_store) { |
| 212 | ti->error = "Exception store allocation failed"; |
| 213 | return -ENOMEM; |
| 214 | } |
| 215 | |
| 216 | persistent = toupper(*argv[0]); |
| 217 | if (persistent == 'P') |
| 218 | type = get_type("P"); |
| 219 | else if (persistent == 'N') |
| 220 | type = get_type("N"); |
| 221 | else { |
| 222 | ti->error = "Persistent flag is not P or N"; |
| 223 | r = -EINVAL; |
| 224 | goto bad_type; |
| 225 | } |
| 226 | |
| 227 | if (!type) { |
| 228 | ti->error = "Exception store type not recognised"; |
| 229 | r = -EINVAL; |
| 230 | goto bad_type; |
| 231 | } |
| 232 | |
| 233 | tmp_store->type = type; |
| 234 | tmp_store->snap = snap; |
| 235 | |
| 236 | r = set_chunk_size(tmp_store, argv[1], &ti->error); |
| 237 | if (r) |
| 238 | goto bad; |
| 239 | |
| 240 | r = type->ctr(tmp_store, 0, NULL); |
| 241 | if (r) { |
| 242 | ti->error = "Exception store type constructor failed"; |
| 243 | goto bad; |
| 244 | } |
| 245 | |
| 246 | *args_used = 2; |
| 247 | *store = tmp_store; |
| 248 | return 0; |
| 249 | |
| 250 | bad: |
| 251 | put_type(type); |
| 252 | bad_type: |
| 253 | kfree(tmp_store); |
| 254 | return r; |
| 255 | } |
| 256 | EXPORT_SYMBOL(dm_exception_store_create); |
| 257 | |
| 258 | void dm_exception_store_destroy(struct dm_exception_store *store) |
| 259 | { |
| 260 | store->type->dtr(store); |
| 261 | put_type(store->type); |
| 262 | kfree(store); |
| 263 | } |
| 264 | EXPORT_SYMBOL(dm_exception_store_destroy); |
| 265 | |
| 266 | int dm_exception_store_init(void) |
| 267 | { |
| 268 | int r; |
| 269 | |
| 270 | r = dm_transient_snapshot_init(); |
| 271 | if (r) { |
| 272 | DMERR("Unable to register transient exception store type."); |
| 273 | goto transient_fail; |
| 274 | } |
| 275 | |
| 276 | r = dm_persistent_snapshot_init(); |
| 277 | if (r) { |
| 278 | DMERR("Unable to register persistent exception store type"); |
| 279 | goto persistent_fail; |
| 280 | } |
| 281 | |
| 282 | return 0; |
| 283 | |
| 284 | persistent_fail: |
| 285 | dm_persistent_snapshot_exit(); |
| 286 | transient_fail: |
| 287 | return r; |
| 288 | } |
| 289 | |
| 290 | void dm_exception_store_exit(void) |
| 291 | { |
| 292 | dm_persistent_snapshot_exit(); |
| 293 | dm_transient_snapshot_exit(); |
| 294 | } |