| 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 "inode.hpp" |
| 9 | |
| 10 | #include <common/defaults.hpp> |
| 11 | #include <common/error.hpp> |
| 12 | #include <common/hashtable/utils.hpp> |
| 13 | #include <common/macros.hpp> |
| 14 | #include <common/optional.hpp> |
| 15 | #include <common/string-utils/format.hpp> |
| 16 | #include <common/urcu.hpp> |
| 17 | #include <common/utils.hpp> |
| 18 | |
| 19 | #include <lttng/constant.h> |
| 20 | |
| 21 | #include <inttypes.h> |
| 22 | #include <sys/stat.h> |
| 23 | #include <sys/types.h> |
| 24 | #include <unistd.h> |
| 25 | #include <urcu.h> |
| 26 | #include <urcu/rculfhash.h> |
| 27 | #include <urcu/ref.h> |
| 28 | |
| 29 | namespace { |
| 30 | struct inode_id { |
| 31 | dev_t device; |
| 32 | ino_t inode; |
| 33 | }; |
| 34 | } /* namespace */ |
| 35 | |
| 36 | struct lttng_inode_registry { |
| 37 | /* Hashtable of inode_id to lttng_inode. */ |
| 38 | struct cds_lfht *inodes; |
| 39 | }; |
| 40 | |
| 41 | struct lttng_inode { |
| 42 | struct inode_id id; |
| 43 | /* Node in the lttng_inode_registry's ht. */ |
| 44 | struct cds_lfht_node registry_node; |
| 45 | /* Weak reference to ht containing the node. */ |
| 46 | struct cds_lfht *registry_ht; |
| 47 | struct urcu_ref ref; |
| 48 | struct rcu_head rcu_head; |
| 49 | /* Location from which this file can be opened. */ |
| 50 | struct { |
| 51 | struct lttng_directory_handle *directory_handle; |
| 52 | char *path; |
| 53 | } location; |
| 54 | /* Unlink the underlying file at the release of the inode. */ |
| 55 | bool unlink_pending; |
| 56 | LTTNG_OPTIONAL(unsigned int) unlinked_id; |
| 57 | /* Weak reference. */ |
| 58 | struct lttng_unlinked_file_pool *unlinked_file_pool; |
| 59 | }; |
| 60 | |
| 61 | struct lttng_unlinked_file_pool { |
| 62 | struct lttng_directory_handle *unlink_directory_handle; |
| 63 | char *unlink_directory_path; |
| 64 | unsigned int file_count; |
| 65 | unsigned int next_id; |
| 66 | }; |
| 67 | |
| 68 | namespace { |
| 69 | struct { |
| 70 | pthread_mutex_t lock; |
| 71 | bool initialized; |
| 72 | unsigned long value; |
| 73 | } seed = { |
| 74 | .lock = PTHREAD_MUTEX_INITIALIZER, |
| 75 | .initialized = false, |
| 76 | .value = 0, |
| 77 | }; |
| 78 | } /* namespace */ |
| 79 | |
| 80 | static unsigned long lttng_inode_id_hash(const struct inode_id *id) |
| 81 | { |
| 82 | uint64_t device = id->device, inode_no = id->inode; |
| 83 | |
| 84 | return hash_key_u64(&device, seed.value) ^ hash_key_u64(&inode_no, seed.value); |
| 85 | } |
| 86 | |
| 87 | static int lttng_inode_match(struct cds_lfht_node *node, const void *key) |
| 88 | { |
| 89 | const struct inode_id *id = (inode_id *) key; |
| 90 | const struct lttng_inode *inode = |
| 91 | lttng::utils::container_of(node, <tng_inode::registry_node); |
| 92 | |
| 93 | return inode->id.device == id->device && inode->id.inode == id->inode; |
| 94 | } |
| 95 | |
| 96 | static void lttng_inode_free(struct rcu_head *head) |
| 97 | { |
| 98 | struct lttng_inode *inode = lttng::utils::container_of(head, <tng_inode::rcu_head); |
| 99 | |
| 100 | free(inode); |
| 101 | } |
| 102 | |
| 103 | static int lttng_unlinked_file_pool_add_inode(struct lttng_unlinked_file_pool *pool, |
| 104 | struct lttng_inode *inode) |
| 105 | { |
| 106 | int ret; |
| 107 | const unsigned int unlinked_id = pool->next_id++; |
| 108 | char *inode_unlinked_name; |
| 109 | bool reference_acquired; |
| 110 | |
| 111 | DBG("Adding inode of %s to unlinked file pool as id %u", inode->location.path, unlinked_id); |
| 112 | ret = asprintf(&inode_unlinked_name, "%u", unlinked_id); |
| 113 | if (ret < 0) { |
| 114 | ERR("Failed to format unlinked inode name"); |
| 115 | ret = -1; |
| 116 | goto end; |
| 117 | } |
| 118 | |
| 119 | if (pool->file_count == 0) { |
| 120 | DBG("Creating unlinked files directory at %s", pool->unlink_directory_path); |
| 121 | LTTNG_ASSERT(!pool->unlink_directory_handle); |
| 122 | ret = utils_mkdir(pool->unlink_directory_path, S_IRWXU | S_IRWXG, -1, -1); |
| 123 | if (ret) { |
| 124 | if (errno == EEXIST) { |
| 125 | /* |
| 126 | * Unexpected (previous crash?), but not an |
| 127 | * error. |
| 128 | */ |
| 129 | DBG("Unlinked file directory \"%s\" already exists", |
| 130 | pool->unlink_directory_path); |
| 131 | } else { |
| 132 | PERROR("Failed to create unlinked files directory at %s", |
| 133 | pool->unlink_directory_path); |
| 134 | goto end; |
| 135 | } |
| 136 | } |
| 137 | pool->unlink_directory_handle = |
| 138 | lttng_directory_handle_create(pool->unlink_directory_path); |
| 139 | if (!pool->unlink_directory_handle) { |
| 140 | ERR("Failed to create directory handle to unlinked file pool at %s", |
| 141 | pool->unlink_directory_path); |
| 142 | ret = -1; |
| 143 | goto end; |
| 144 | } |
| 145 | } |
| 146 | |
| 147 | ret = lttng_directory_handle_rename(inode->location.directory_handle, |
| 148 | inode->location.path, |
| 149 | pool->unlink_directory_handle, |
| 150 | inode_unlinked_name); |
| 151 | if (ret) { |
| 152 | goto end; |
| 153 | } |
| 154 | |
| 155 | lttng_directory_handle_put(inode->location.directory_handle); |
| 156 | inode->location.directory_handle = nullptr; |
| 157 | reference_acquired = lttng_directory_handle_get(pool->unlink_directory_handle); |
| 158 | LTTNG_ASSERT(reference_acquired); |
| 159 | inode->location.directory_handle = pool->unlink_directory_handle; |
| 160 | |
| 161 | free(inode->location.path); |
| 162 | inode->location.path = inode_unlinked_name; |
| 163 | inode_unlinked_name = nullptr; |
| 164 | LTTNG_OPTIONAL_SET(&inode->unlinked_id, unlinked_id); |
| 165 | pool->file_count++; |
| 166 | end: |
| 167 | free(inode_unlinked_name); |
| 168 | return ret; |
| 169 | } |
| 170 | |
| 171 | static int lttng_unlinked_file_pool_remove_inode(struct lttng_unlinked_file_pool *pool, |
| 172 | struct lttng_inode *inode) |
| 173 | { |
| 174 | int ret; |
| 175 | |
| 176 | DBG("Removing inode with unlinked id %u from unlinked file pool", |
| 177 | LTTNG_OPTIONAL_GET(inode->unlinked_id)); |
| 178 | |
| 179 | ret = lttng_directory_handle_unlink_file(inode->location.directory_handle, |
| 180 | inode->location.path); |
| 181 | if (ret) { |
| 182 | PERROR("Failed to unlink file %s from unlinked file directory", |
| 183 | inode->location.path); |
| 184 | goto end; |
| 185 | } |
| 186 | free(inode->location.path); |
| 187 | inode->location.path = nullptr; |
| 188 | lttng_directory_handle_put(inode->location.directory_handle); |
| 189 | inode->location.directory_handle = nullptr; |
| 190 | |
| 191 | pool->file_count--; |
| 192 | if (pool->file_count == 0) { |
| 193 | ret = utils_recursive_rmdir(pool->unlink_directory_path); |
| 194 | if (ret) { |
| 195 | /* |
| 196 | * There is nothing the caller can do, don't report an |
| 197 | * error except through logging. |
| 198 | */ |
| 199 | PERROR("Failed to remove unlinked files directory at %s", |
| 200 | pool->unlink_directory_path); |
| 201 | } |
| 202 | lttng_directory_handle_put(pool->unlink_directory_handle); |
| 203 | pool->unlink_directory_handle = nullptr; |
| 204 | } |
| 205 | end: |
| 206 | return ret; |
| 207 | } |
| 208 | |
| 209 | static void lttng_inode_destroy(struct lttng_inode *inode) |
| 210 | { |
| 211 | if (!inode) { |
| 212 | return; |
| 213 | } |
| 214 | |
| 215 | lttng::urcu::read_lock_guard read_lock; |
| 216 | cds_lfht_del(inode->registry_ht, &inode->registry_node); |
| 217 | |
| 218 | if (inode->unlink_pending) { |
| 219 | int ret; |
| 220 | |
| 221 | LTTNG_ASSERT(inode->location.directory_handle); |
| 222 | LTTNG_ASSERT(inode->location.path); |
| 223 | DBG("Removing %s from unlinked file pool", inode->location.path); |
| 224 | ret = lttng_unlinked_file_pool_remove_inode(inode->unlinked_file_pool, inode); |
| 225 | if (ret) { |
| 226 | PERROR("Failed to unlink %s", inode->location.path); |
| 227 | } |
| 228 | } |
| 229 | |
| 230 | lttng_directory_handle_put(inode->location.directory_handle); |
| 231 | inode->location.directory_handle = nullptr; |
| 232 | free(inode->location.path); |
| 233 | inode->location.path = nullptr; |
| 234 | call_rcu(&inode->rcu_head, lttng_inode_free); |
| 235 | } |
| 236 | |
| 237 | static void lttng_inode_release(struct urcu_ref *ref) |
| 238 | { |
| 239 | lttng_inode_destroy(lttng::utils::container_of(ref, <tng_inode::ref)); |
| 240 | } |
| 241 | |
| 242 | static void lttng_inode_get(struct lttng_inode *inode) |
| 243 | { |
| 244 | urcu_ref_get(&inode->ref); |
| 245 | } |
| 246 | |
| 247 | struct lttng_unlinked_file_pool *lttng_unlinked_file_pool_create(const char *path) |
| 248 | { |
| 249 | struct lttng_unlinked_file_pool *pool = zmalloc<lttng_unlinked_file_pool>(); |
| 250 | |
| 251 | if (!pool) { |
| 252 | goto error; |
| 253 | } |
| 254 | |
| 255 | if (!path || *path != '/') { |
| 256 | ERR("Unlinked file pool must be created with an absolute path, path = \"%s\"", |
| 257 | path ? path : "NULL"); |
| 258 | goto error; |
| 259 | } |
| 260 | |
| 261 | pool->unlink_directory_path = strdup(path); |
| 262 | if (!pool->unlink_directory_path) { |
| 263 | PERROR("Failed to allocation unlinked file pool path"); |
| 264 | goto error; |
| 265 | } |
| 266 | DBG("Unlinked file pool created at: %s", path); |
| 267 | return pool; |
| 268 | error: |
| 269 | lttng_unlinked_file_pool_destroy(pool); |
| 270 | return nullptr; |
| 271 | } |
| 272 | |
| 273 | void lttng_unlinked_file_pool_destroy(struct lttng_unlinked_file_pool *pool) |
| 274 | { |
| 275 | if (!pool) { |
| 276 | return; |
| 277 | } |
| 278 | |
| 279 | LTTNG_ASSERT(pool->file_count == 0); |
| 280 | lttng_directory_handle_put(pool->unlink_directory_handle); |
| 281 | free(pool->unlink_directory_path); |
| 282 | free(pool); |
| 283 | } |
| 284 | |
| 285 | void lttng_inode_put(struct lttng_inode *inode) |
| 286 | { |
| 287 | urcu_ref_put(&inode->ref, lttng_inode_release); |
| 288 | } |
| 289 | |
| 290 | struct lttng_directory_handle *lttng_inode_get_location_directory_handle(struct lttng_inode *inode) |
| 291 | { |
| 292 | if (inode->location.directory_handle) { |
| 293 | const bool reference_acquired = |
| 294 | lttng_directory_handle_get(inode->location.directory_handle); |
| 295 | |
| 296 | LTTNG_ASSERT(reference_acquired); |
| 297 | } |
| 298 | return inode->location.directory_handle; |
| 299 | } |
| 300 | |
| 301 | void lttng_inode_borrow_location(struct lttng_inode *inode, |
| 302 | const struct lttng_directory_handle **out_directory_handle, |
| 303 | const char **out_path) |
| 304 | { |
| 305 | if (out_directory_handle) { |
| 306 | *out_directory_handle = inode->location.directory_handle; |
| 307 | } |
| 308 | if (out_path) { |
| 309 | *out_path = inode->location.path; |
| 310 | } |
| 311 | } |
| 312 | |
| 313 | int lttng_inode_rename(struct lttng_inode *inode, |
| 314 | struct lttng_directory_handle *old_directory_handle, |
| 315 | const char *old_path, |
| 316 | struct lttng_directory_handle *new_directory_handle, |
| 317 | const char *new_path, |
| 318 | bool overwrite) |
| 319 | { |
| 320 | int ret = 0; |
| 321 | char *new_path_copy = strdup(new_path); |
| 322 | bool reference_acquired; |
| 323 | |
| 324 | DBG("Performing rename of inode from %s to %s with %s directory handles", |
| 325 | old_path, |
| 326 | new_path, |
| 327 | lttng_directory_handle_equals(old_directory_handle, new_directory_handle) ? |
| 328 | "identical" : |
| 329 | "different"); |
| 330 | |
| 331 | if (!new_path_copy) { |
| 332 | ret = -ENOMEM; |
| 333 | goto end; |
| 334 | } |
| 335 | |
| 336 | if (inode->unlink_pending) { |
| 337 | WARN("An attempt to rename an unlinked file from %s to %s has been performed", |
| 338 | old_path, |
| 339 | new_path); |
| 340 | ret = -ENOENT; |
| 341 | goto end; |
| 342 | } |
| 343 | |
| 344 | if (!overwrite) { |
| 345 | /* Verify that file doesn't exist. */ |
| 346 | struct stat statbuf; |
| 347 | |
| 348 | ret = lttng_directory_handle_stat(new_directory_handle, new_path, &statbuf); |
| 349 | if (ret == 0) { |
| 350 | ERR("Refusing to rename %s as the destination already exists", old_path); |
| 351 | ret = -EEXIST; |
| 352 | goto end; |
| 353 | } else if (ret < 0 && errno != ENOENT) { |
| 354 | PERROR("Failed to stat() %s", new_path); |
| 355 | ret = -errno; |
| 356 | goto end; |
| 357 | } |
| 358 | } |
| 359 | |
| 360 | ret = lttng_directory_handle_rename( |
| 361 | old_directory_handle, old_path, new_directory_handle, new_path); |
| 362 | if (ret) { |
| 363 | PERROR("Failed to rename file %s to %s", old_path, new_path); |
| 364 | ret = -errno; |
| 365 | goto end; |
| 366 | } |
| 367 | |
| 368 | reference_acquired = lttng_directory_handle_get(new_directory_handle); |
| 369 | LTTNG_ASSERT(reference_acquired); |
| 370 | lttng_directory_handle_put(inode->location.directory_handle); |
| 371 | free(inode->location.path); |
| 372 | inode->location.directory_handle = new_directory_handle; |
| 373 | /* Ownership transferred. */ |
| 374 | inode->location.path = new_path_copy; |
| 375 | new_path_copy = nullptr; |
| 376 | end: |
| 377 | free(new_path_copy); |
| 378 | return ret; |
| 379 | } |
| 380 | |
| 381 | int lttng_inode_unlink(struct lttng_inode *inode) |
| 382 | { |
| 383 | int ret = 0; |
| 384 | |
| 385 | DBG("Attempting unlink of inode %s", inode->location.path); |
| 386 | |
| 387 | if (inode->unlink_pending) { |
| 388 | WARN("An attempt to re-unlink %s has been performed, ignoring.", |
| 389 | inode->location.path); |
| 390 | ret = -ENOENT; |
| 391 | goto end; |
| 392 | } |
| 393 | |
| 394 | /* |
| 395 | * Move to the temporary "deleted" directory until all |
| 396 | * references are released. |
| 397 | */ |
| 398 | ret = lttng_unlinked_file_pool_add_inode(inode->unlinked_file_pool, inode); |
| 399 | if (ret) { |
| 400 | PERROR("Failed to add inode \"%s\" to the unlinked file pool", |
| 401 | inode->location.path); |
| 402 | goto end; |
| 403 | } |
| 404 | inode->unlink_pending = true; |
| 405 | end: |
| 406 | return ret; |
| 407 | } |
| 408 | |
| 409 | static struct lttng_inode *lttng_inode_create(const struct inode_id *id, |
| 410 | struct cds_lfht *ht, |
| 411 | struct lttng_unlinked_file_pool *unlinked_file_pool, |
| 412 | struct lttng_directory_handle *directory_handle, |
| 413 | const char *path) |
| 414 | { |
| 415 | struct lttng_inode *inode = nullptr; |
| 416 | char *path_copy; |
| 417 | bool reference_acquired; |
| 418 | |
| 419 | path_copy = strdup(path); |
| 420 | if (!path_copy) { |
| 421 | goto end; |
| 422 | } |
| 423 | |
| 424 | reference_acquired = lttng_directory_handle_get(directory_handle); |
| 425 | LTTNG_ASSERT(reference_acquired); |
| 426 | |
| 427 | inode = zmalloc<lttng_inode>(); |
| 428 | if (!inode) { |
| 429 | goto end; |
| 430 | } |
| 431 | |
| 432 | urcu_ref_init(&inode->ref); |
| 433 | cds_lfht_node_init(&inode->registry_node); |
| 434 | inode->id = *id; |
| 435 | inode->registry_ht = ht; |
| 436 | inode->unlinked_file_pool = unlinked_file_pool; |
| 437 | /* Ownership of path copy is transferred to inode. */ |
| 438 | inode->location.path = path_copy; |
| 439 | path_copy = nullptr; |
| 440 | inode->location.directory_handle = directory_handle; |
| 441 | end: |
| 442 | free(path_copy); |
| 443 | return inode; |
| 444 | } |
| 445 | |
| 446 | struct lttng_inode_registry *lttng_inode_registry_create() |
| 447 | { |
| 448 | struct lttng_inode_registry *registry = zmalloc<lttng_inode_registry>(); |
| 449 | |
| 450 | if (!registry) { |
| 451 | goto end; |
| 452 | } |
| 453 | |
| 454 | pthread_mutex_lock(&seed.lock); |
| 455 | if (!seed.initialized) { |
| 456 | seed.value = (unsigned long) time(nullptr); |
| 457 | seed.initialized = true; |
| 458 | } |
| 459 | pthread_mutex_unlock(&seed.lock); |
| 460 | |
| 461 | registry->inodes = cds_lfht_new( |
| 462 | DEFAULT_HT_SIZE, 1, 0, CDS_LFHT_AUTO_RESIZE | CDS_LFHT_ACCOUNTING, nullptr); |
| 463 | if (!registry->inodes) { |
| 464 | goto error; |
| 465 | } |
| 466 | end: |
| 467 | return registry; |
| 468 | error: |
| 469 | lttng_inode_registry_destroy(registry); |
| 470 | return nullptr; |
| 471 | } |
| 472 | |
| 473 | void lttng_inode_registry_destroy(struct lttng_inode_registry *registry) |
| 474 | { |
| 475 | if (!registry) { |
| 476 | return; |
| 477 | } |
| 478 | if (registry->inodes) { |
| 479 | int ret = cds_lfht_destroy(registry->inodes, nullptr); |
| 480 | |
| 481 | LTTNG_ASSERT(!ret); |
| 482 | } |
| 483 | free(registry); |
| 484 | } |
| 485 | |
| 486 | struct lttng_inode * |
| 487 | lttng_inode_registry_get_inode(struct lttng_inode_registry *registry, |
| 488 | struct lttng_directory_handle *handle, |
| 489 | const char *path, |
| 490 | int fd, |
| 491 | struct lttng_unlinked_file_pool *unlinked_file_pool) |
| 492 | { |
| 493 | int ret; |
| 494 | struct stat statbuf; |
| 495 | struct inode_id id; |
| 496 | struct cds_lfht_iter iter; |
| 497 | struct cds_lfht_node *node; |
| 498 | struct lttng_inode *inode = nullptr; |
| 499 | lttng::urcu::read_lock_guard read_lock; |
| 500 | |
| 501 | ret = fstat(fd, &statbuf); |
| 502 | if (ret < 0) { |
| 503 | PERROR("stat() failed on fd %i", fd); |
| 504 | goto end; |
| 505 | } |
| 506 | |
| 507 | id.device = statbuf.st_dev; |
| 508 | id.inode = statbuf.st_ino; |
| 509 | |
| 510 | cds_lfht_lookup(registry->inodes, lttng_inode_id_hash(&id), lttng_inode_match, &id, &iter); |
| 511 | node = cds_lfht_iter_get_node(&iter); |
| 512 | if (node) { |
| 513 | inode = lttng::utils::container_of(node, <tng_inode::registry_node); |
| 514 | lttng_inode_get(inode); |
| 515 | goto end; |
| 516 | } |
| 517 | |
| 518 | inode = lttng_inode_create(&id, registry->inodes, unlinked_file_pool, handle, path); |
| 519 | if (!inode) { |
| 520 | goto end; |
| 521 | } |
| 522 | |
| 523 | node = cds_lfht_add_unique(registry->inodes, |
| 524 | lttng_inode_id_hash(&inode->id), |
| 525 | lttng_inode_match, |
| 526 | &inode->id, |
| 527 | &inode->registry_node); |
| 528 | LTTNG_ASSERT(node == &inode->registry_node); |
| 529 | end: |
| 530 | return inode; |
| 531 | } |