| 1 | /* |
| 2 | * Copyright (C) 2020 Jérémie Galarneau <jeremie.galarneau@efficios.com> |
| 3 | * |
| 4 | * SPDX-License-Identifier: GPL-2.0-only |
| 5 | * |
| 6 | */ |
| 7 | |
| 8 | #include <common/defaults.h> |
| 9 | #include <common/error.h> |
| 10 | #include <common/hashtable/utils.h> |
| 11 | #include <common/macros.h> |
| 12 | #include <common/optional.h> |
| 13 | #include <common/string-utils/format.h> |
| 14 | #include <common/utils.h> |
| 15 | #include <inttypes.h> |
| 16 | #include <lttng/constant.h> |
| 17 | #include <sys/stat.h> |
| 18 | #include <sys/types.h> |
| 19 | #include <unistd.h> |
| 20 | #include <urcu.h> |
| 21 | #include <urcu/rculfhash.h> |
| 22 | #include <urcu/ref.h> |
| 23 | |
| 24 | #include "inode.h" |
| 25 | |
| 26 | struct inode_id { |
| 27 | dev_t device; |
| 28 | ino_t inode; |
| 29 | }; |
| 30 | |
| 31 | struct lttng_inode_registry { |
| 32 | /* Hashtable of inode_id to lttng_inode. */ |
| 33 | struct cds_lfht *inodes; |
| 34 | }; |
| 35 | |
| 36 | struct lttng_inode { |
| 37 | struct inode_id id; |
| 38 | /* Node in the lttng_inode_registry's ht. */ |
| 39 | struct cds_lfht_node registry_node; |
| 40 | /* Weak reference to ht containing the node. */ |
| 41 | struct cds_lfht *registry_ht; |
| 42 | struct urcu_ref ref; |
| 43 | struct rcu_head rcu_head; |
| 44 | /* Location from which this file can be opened. */ |
| 45 | struct { |
| 46 | struct lttng_directory_handle *directory_handle; |
| 47 | char *path; |
| 48 | } location; |
| 49 | /* Unlink the underlying file at the release of the inode. */ |
| 50 | bool unlink_pending; |
| 51 | LTTNG_OPTIONAL(unsigned int) unlinked_id; |
| 52 | /* Weak reference. */ |
| 53 | struct lttng_unlinked_file_pool *unlinked_file_pool; |
| 54 | }; |
| 55 | |
| 56 | struct lttng_unlinked_file_pool { |
| 57 | struct lttng_directory_handle *unlink_directory_handle; |
| 58 | char *unlink_directory_path; |
| 59 | unsigned int file_count; |
| 60 | unsigned int next_id; |
| 61 | }; |
| 62 | |
| 63 | static struct { |
| 64 | pthread_mutex_t lock; |
| 65 | bool initialized; |
| 66 | unsigned long value; |
| 67 | } seed = { |
| 68 | .lock = PTHREAD_MUTEX_INITIALIZER, |
| 69 | }; |
| 70 | |
| 71 | static unsigned long lttng_inode_id_hash(const struct inode_id *id) |
| 72 | { |
| 73 | uint64_t device = id->device, inode_no = id->inode; |
| 74 | |
| 75 | return hash_key_u64(&device, seed.value) ^ |
| 76 | hash_key_u64(&inode_no, seed.value); |
| 77 | } |
| 78 | |
| 79 | static int lttng_inode_match(struct cds_lfht_node *node, const void *key) |
| 80 | { |
| 81 | const struct inode_id *id = key; |
| 82 | const struct lttng_inode *inode = caa_container_of( |
| 83 | node, struct lttng_inode, registry_node); |
| 84 | |
| 85 | return inode->id.device == id->device && inode->id.inode == id->inode; |
| 86 | } |
| 87 | |
| 88 | static void lttng_inode_free(struct rcu_head *head) |
| 89 | { |
| 90 | struct lttng_inode *inode = |
| 91 | caa_container_of(head, struct lttng_inode, rcu_head); |
| 92 | |
| 93 | free(inode); |
| 94 | } |
| 95 | |
| 96 | static int lttng_unlinked_file_pool_add_inode( |
| 97 | struct lttng_unlinked_file_pool *pool, |
| 98 | struct lttng_inode *inode) |
| 99 | { |
| 100 | int ret; |
| 101 | const unsigned int unlinked_id = pool->next_id++; |
| 102 | char *inode_unlinked_name; |
| 103 | bool reference_acquired; |
| 104 | |
| 105 | DBG("Adding inode of %s to unlinked file pool as id %u", |
| 106 | inode->location.path, unlinked_id); |
| 107 | ret = asprintf(&inode_unlinked_name, "%u", unlinked_id); |
| 108 | if (ret < 0) { |
| 109 | ERR("Failed to format unlinked inode name"); |
| 110 | ret = -1; |
| 111 | goto end; |
| 112 | } |
| 113 | |
| 114 | if (pool->file_count == 0) { |
| 115 | DBG("Creating unlinked files directory at %s", |
| 116 | pool->unlink_directory_path); |
| 117 | assert(!pool->unlink_directory_handle); |
| 118 | ret = utils_mkdir(pool->unlink_directory_path, |
| 119 | S_IRWXU | S_IRWXG, -1, -1); |
| 120 | if (ret) { |
| 121 | if (errno == EEXIST) { |
| 122 | /* |
| 123 | * Unexpected (previous crash?), but not an |
| 124 | * error. |
| 125 | */ |
| 126 | DBG("Unlinked file directory \"%s\" already exists", |
| 127 | pool->unlink_directory_path); |
| 128 | } else { |
| 129 | PERROR("Failed to create unlinked files directory at %s", |
| 130 | pool->unlink_directory_path); |
| 131 | goto end; |
| 132 | } |
| 133 | } |
| 134 | pool->unlink_directory_handle = lttng_directory_handle_create( |
| 135 | pool->unlink_directory_path); |
| 136 | } |
| 137 | |
| 138 | ret = lttng_directory_handle_rename(inode->location.directory_handle, |
| 139 | inode->location.path, pool->unlink_directory_handle, |
| 140 | inode_unlinked_name); |
| 141 | if (ret) { |
| 142 | goto end; |
| 143 | } |
| 144 | |
| 145 | lttng_directory_handle_put(inode->location.directory_handle); |
| 146 | inode->location.directory_handle = NULL; |
| 147 | reference_acquired = lttng_directory_handle_get( |
| 148 | pool->unlink_directory_handle); |
| 149 | assert(reference_acquired); |
| 150 | inode->location.directory_handle = pool->unlink_directory_handle; |
| 151 | |
| 152 | free(inode->location.path); |
| 153 | inode->location.path = inode_unlinked_name; |
| 154 | inode_unlinked_name = NULL; |
| 155 | LTTNG_OPTIONAL_SET(&inode->unlinked_id, unlinked_id); |
| 156 | pool->file_count++; |
| 157 | end: |
| 158 | free(inode_unlinked_name); |
| 159 | return ret; |
| 160 | } |
| 161 | |
| 162 | static int lttng_unlinked_file_pool_remove_inode( |
| 163 | struct lttng_unlinked_file_pool *pool, |
| 164 | struct lttng_inode *inode) |
| 165 | { |
| 166 | int ret; |
| 167 | |
| 168 | DBG("Removing inode with unlinked id %u from unlinked file pool", |
| 169 | LTTNG_OPTIONAL_GET(inode->unlinked_id)); |
| 170 | |
| 171 | ret = lttng_directory_handle_unlink_file( |
| 172 | inode->location.directory_handle, inode->location.path); |
| 173 | if (ret) { |
| 174 | PERROR("Failed to unlink file %s from unlinked file directory", |
| 175 | inode->location.path); |
| 176 | goto end; |
| 177 | } |
| 178 | free(inode->location.path); |
| 179 | inode->location.path = NULL; |
| 180 | lttng_directory_handle_put(inode->location.directory_handle); |
| 181 | inode->location.directory_handle = NULL; |
| 182 | |
| 183 | pool->file_count--; |
| 184 | if (pool->file_count == 0) { |
| 185 | ret = utils_recursive_rmdir(pool->unlink_directory_path); |
| 186 | if (ret) { |
| 187 | /* |
| 188 | * There is nothing the caller can do, don't report an |
| 189 | * error except through logging. |
| 190 | */ |
| 191 | PERROR("Failed to remove unlinked files directory at %s", |
| 192 | pool->unlink_directory_path); |
| 193 | } |
| 194 | lttng_directory_handle_put(pool->unlink_directory_handle); |
| 195 | pool->unlink_directory_handle = NULL; |
| 196 | } |
| 197 | end: |
| 198 | return ret; |
| 199 | } |
| 200 | |
| 201 | static void lttng_inode_destroy(struct lttng_inode *inode) |
| 202 | { |
| 203 | if (!inode) { |
| 204 | return; |
| 205 | } |
| 206 | |
| 207 | rcu_read_lock(); |
| 208 | cds_lfht_del(inode->registry_ht, &inode->registry_node); |
| 209 | rcu_read_unlock(); |
| 210 | |
| 211 | if (inode->unlink_pending) { |
| 212 | int ret; |
| 213 | |
| 214 | assert(inode->location.directory_handle); |
| 215 | assert(inode->location.path); |
| 216 | DBG("Removing %s from unlinked file pool", |
| 217 | inode->location.path); |
| 218 | ret = lttng_unlinked_file_pool_remove_inode(inode->unlinked_file_pool, inode); |
| 219 | if (ret) { |
| 220 | PERROR("Failed to unlink %s", inode->location.path); |
| 221 | } |
| 222 | } |
| 223 | |
| 224 | lttng_directory_handle_put( |
| 225 | inode->location.directory_handle); |
| 226 | inode->location.directory_handle = NULL; |
| 227 | free(inode->location.path); |
| 228 | inode->location.path = NULL; |
| 229 | call_rcu(&inode->rcu_head, lttng_inode_free); |
| 230 | } |
| 231 | |
| 232 | static void lttng_inode_release(struct urcu_ref *ref) |
| 233 | { |
| 234 | lttng_inode_destroy(caa_container_of(ref, struct lttng_inode, ref)); |
| 235 | } |
| 236 | |
| 237 | static void lttng_inode_get(struct lttng_inode *inode) |
| 238 | { |
| 239 | urcu_ref_get(&inode->ref); |
| 240 | } |
| 241 | |
| 242 | struct lttng_unlinked_file_pool *lttng_unlinked_file_pool_create( |
| 243 | const char *path) |
| 244 | { |
| 245 | struct lttng_unlinked_file_pool *pool = zmalloc(sizeof(*pool)); |
| 246 | |
| 247 | if (!path || *path != '/') { |
| 248 | ERR("Unlinked file pool must be created with an absolute path, path = \"%s\"", |
| 249 | path ? path : "NULL"); |
| 250 | goto error; |
| 251 | } |
| 252 | |
| 253 | pool->unlink_directory_path = strdup(path); |
| 254 | if (!pool->unlink_directory_path) { |
| 255 | PERROR("Failed to allocation unlinked file pool path"); |
| 256 | goto error; |
| 257 | } |
| 258 | DBG("Unlinked file pool created at: %s", path); |
| 259 | return pool; |
| 260 | error: |
| 261 | lttng_unlinked_file_pool_destroy(pool); |
| 262 | return NULL; |
| 263 | } |
| 264 | |
| 265 | void lttng_unlinked_file_pool_destroy( |
| 266 | struct lttng_unlinked_file_pool *pool) |
| 267 | { |
| 268 | if (!pool) { |
| 269 | return; |
| 270 | } |
| 271 | |
| 272 | assert(pool->file_count == 0); |
| 273 | lttng_directory_handle_put(pool->unlink_directory_handle); |
| 274 | free(pool->unlink_directory_path); |
| 275 | free(pool); |
| 276 | } |
| 277 | |
| 278 | void lttng_inode_put(struct lttng_inode *inode) |
| 279 | { |
| 280 | urcu_ref_put(&inode->ref, lttng_inode_release); |
| 281 | } |
| 282 | |
| 283 | void lttng_inode_get_location(struct lttng_inode *inode, |
| 284 | const struct lttng_directory_handle **out_directory_handle, |
| 285 | const char **out_path) |
| 286 | { |
| 287 | if (out_directory_handle) { |
| 288 | *out_directory_handle = inode->location.directory_handle; |
| 289 | } |
| 290 | if (out_path) { |
| 291 | *out_path = inode->location.path; |
| 292 | } |
| 293 | } |
| 294 | |
| 295 | int lttng_inode_rename( |
| 296 | struct lttng_inode *inode, |
| 297 | struct lttng_directory_handle *old_directory_handle, |
| 298 | const char *old_path, |
| 299 | struct lttng_directory_handle *new_directory_handle, |
| 300 | const char *new_path, |
| 301 | bool overwrite) |
| 302 | { |
| 303 | int ret = 0; |
| 304 | char *new_path_copy = strdup(new_path); |
| 305 | bool reference_acquired; |
| 306 | |
| 307 | DBG("Performing rename of inode from %s to %s with %s directory handles", |
| 308 | old_path, new_path, |
| 309 | lttng_directory_handle_equals(old_directory_handle, |
| 310 | new_directory_handle) ? |
| 311 | "identical" : |
| 312 | "different"); |
| 313 | |
| 314 | if (!new_path_copy) { |
| 315 | ret = -ENOMEM; |
| 316 | goto end; |
| 317 | } |
| 318 | |
| 319 | if (inode->unlink_pending) { |
| 320 | WARN("An attempt to rename an unlinked file from %s to %s has been performed", |
| 321 | old_path, new_path); |
| 322 | ret = -ENOENT; |
| 323 | goto end; |
| 324 | } |
| 325 | |
| 326 | if (!overwrite) { |
| 327 | /* Verify that file doesn't exist. */ |
| 328 | struct stat statbuf; |
| 329 | |
| 330 | ret = lttng_directory_handle_stat( |
| 331 | new_directory_handle, new_path, &statbuf); |
| 332 | if (ret == 0) { |
| 333 | ERR("Refusing to rename %s as the destination already exists", |
| 334 | old_path); |
| 335 | ret = -EEXIST; |
| 336 | goto end; |
| 337 | } else if (ret < 0 && errno != ENOENT) { |
| 338 | PERROR("Failed to stat() %s", new_path); |
| 339 | ret = -errno; |
| 340 | goto end; |
| 341 | } |
| 342 | } |
| 343 | |
| 344 | ret = lttng_directory_handle_rename(old_directory_handle, old_path, |
| 345 | new_directory_handle, new_path); |
| 346 | if (ret) { |
| 347 | PERROR("Failed to rename file %s to %s", old_path, new_path); |
| 348 | ret = -errno; |
| 349 | goto end; |
| 350 | } |
| 351 | |
| 352 | reference_acquired = lttng_directory_handle_get(new_directory_handle); |
| 353 | assert(reference_acquired); |
| 354 | lttng_directory_handle_put(inode->location.directory_handle); |
| 355 | free(inode->location.path); |
| 356 | inode->location.directory_handle = new_directory_handle; |
| 357 | /* Ownership transferred. */ |
| 358 | inode->location.path = new_path_copy; |
| 359 | new_path_copy = NULL; |
| 360 | end: |
| 361 | free(new_path_copy); |
| 362 | return ret; |
| 363 | } |
| 364 | |
| 365 | int lttng_inode_unlink(struct lttng_inode *inode) |
| 366 | { |
| 367 | int ret = 0; |
| 368 | |
| 369 | DBG("Attempting unlink of inode %s", inode->location.path); |
| 370 | |
| 371 | if (inode->unlink_pending) { |
| 372 | WARN("An attempt to re-unlink %s has been performed, ignoring.", |
| 373 | inode->location.path); |
| 374 | ret = -ENOENT; |
| 375 | goto end; |
| 376 | } |
| 377 | |
| 378 | /* |
| 379 | * Move to the temporary "deleted" directory until all |
| 380 | * references are released. |
| 381 | */ |
| 382 | ret = lttng_unlinked_file_pool_add_inode( |
| 383 | inode->unlinked_file_pool, inode); |
| 384 | if (ret) { |
| 385 | PERROR("Failed to add inode \"%s\" to the unlinked file pool", |
| 386 | inode->location.path); |
| 387 | goto end; |
| 388 | } |
| 389 | inode->unlink_pending = true; |
| 390 | end: |
| 391 | return ret; |
| 392 | } |
| 393 | |
| 394 | static struct lttng_inode *lttng_inode_create(const struct inode_id *id, |
| 395 | struct cds_lfht *ht, |
| 396 | struct lttng_unlinked_file_pool *unlinked_file_pool, |
| 397 | struct lttng_directory_handle *directory_handle, |
| 398 | const char *path) |
| 399 | { |
| 400 | struct lttng_inode *inode = NULL; |
| 401 | char *path_copy; |
| 402 | bool reference_acquired; |
| 403 | |
| 404 | path_copy = strdup(path); |
| 405 | if (!path_copy) { |
| 406 | goto end; |
| 407 | } |
| 408 | |
| 409 | reference_acquired = lttng_directory_handle_get(directory_handle); |
| 410 | assert(reference_acquired); |
| 411 | |
| 412 | inode = zmalloc(sizeof(*inode)); |
| 413 | if (!inode) { |
| 414 | goto end; |
| 415 | } |
| 416 | |
| 417 | urcu_ref_init(&inode->ref); |
| 418 | cds_lfht_node_init(&inode->registry_node); |
| 419 | inode->id = *id; |
| 420 | inode->registry_ht = ht; |
| 421 | inode->unlinked_file_pool = unlinked_file_pool; |
| 422 | /* Ownership of path copy is transferred to inode. */ |
| 423 | inode->location.path = path_copy; |
| 424 | path_copy = NULL; |
| 425 | inode->location.directory_handle = directory_handle; |
| 426 | end: |
| 427 | free(path_copy); |
| 428 | return inode; |
| 429 | } |
| 430 | |
| 431 | struct lttng_inode_registry *lttng_inode_registry_create(void) |
| 432 | { |
| 433 | struct lttng_inode_registry *registry = zmalloc(sizeof(*registry)); |
| 434 | |
| 435 | if (!registry) { |
| 436 | goto end; |
| 437 | } |
| 438 | |
| 439 | pthread_mutex_lock(&seed.lock); |
| 440 | if (!seed.initialized) { |
| 441 | seed.value = (unsigned long) time(NULL); |
| 442 | seed.initialized = true; |
| 443 | } |
| 444 | pthread_mutex_unlock(&seed.lock); |
| 445 | |
| 446 | registry->inodes = cds_lfht_new(DEFAULT_HT_SIZE, 1, 0, |
| 447 | CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING, NULL); |
| 448 | if (!registry->inodes) { |
| 449 | goto error; |
| 450 | } |
| 451 | end: |
| 452 | return registry; |
| 453 | error: |
| 454 | lttng_inode_registry_destroy(registry); |
| 455 | return NULL; |
| 456 | } |
| 457 | |
| 458 | void lttng_inode_registry_destroy(struct lttng_inode_registry *registry) |
| 459 | { |
| 460 | if (!registry) { |
| 461 | return; |
| 462 | } |
| 463 | if (registry->inodes) { |
| 464 | int ret = cds_lfht_destroy(registry->inodes, NULL); |
| 465 | |
| 466 | assert(!ret); |
| 467 | } |
| 468 | free(registry); |
| 469 | } |
| 470 | |
| 471 | struct lttng_inode *lttng_inode_registry_get_inode( |
| 472 | struct lttng_inode_registry *registry, |
| 473 | struct lttng_directory_handle *handle, |
| 474 | const char *path, |
| 475 | int fd, |
| 476 | struct lttng_unlinked_file_pool *unlinked_file_pool) |
| 477 | { |
| 478 | int ret; |
| 479 | struct stat statbuf; |
| 480 | struct inode_id id; |
| 481 | struct cds_lfht_iter iter; |
| 482 | struct cds_lfht_node *node; |
| 483 | struct lttng_inode *inode = NULL; |
| 484 | |
| 485 | ret = fstat(fd, &statbuf); |
| 486 | if (ret < 0) { |
| 487 | PERROR("stat() failed on fd %i", fd); |
| 488 | goto end; |
| 489 | } |
| 490 | |
| 491 | id.device = statbuf.st_dev; |
| 492 | id.inode = statbuf.st_ino; |
| 493 | |
| 494 | rcu_read_lock(); |
| 495 | cds_lfht_lookup(registry->inodes, lttng_inode_id_hash(&id), |
| 496 | lttng_inode_match, &id, &iter); |
| 497 | node = cds_lfht_iter_get_node(&iter); |
| 498 | if (node) { |
| 499 | inode = caa_container_of( |
| 500 | node, struct lttng_inode, registry_node); |
| 501 | lttng_inode_get(inode); |
| 502 | goto end_unlock; |
| 503 | } |
| 504 | |
| 505 | inode = lttng_inode_create(&id, registry->inodes, unlinked_file_pool, |
| 506 | handle, path); |
| 507 | node = cds_lfht_add_unique(registry->inodes, |
| 508 | lttng_inode_id_hash(&inode->id), lttng_inode_match, |
| 509 | &inode->id, &inode->registry_node); |
| 510 | assert(node == &inode->registry_node); |
| 511 | end_unlock: |
| 512 | rcu_read_unlock(); |
| 513 | end: |
| 514 | return inode; |
| 515 | } |