1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* CacheFiles path walking and related routines 3 * 4 * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 8 #include <linux/fs.h> 9 #include <linux/namei.h> 10 #include "internal.h" 11 12 /* 13 * Mark the backing file as being a cache file if it's not already in use. The 14 * mark tells the culling request command that it's not allowed to cull the 15 * file or directory. The caller must hold the inode lock. 16 */ 17 static bool __cachefiles_mark_inode_in_use(struct cachefiles_object *object, 18 struct inode *inode) 19 { 20 bool can_use = false; 21 22 if (!(inode->i_flags & S_KERNEL_FILE)) { 23 inode->i_flags |= S_KERNEL_FILE; 24 trace_cachefiles_mark_active(object, inode); 25 can_use = true; 26 } else { 27 trace_cachefiles_mark_failed(object, inode); 28 } 29 30 return can_use; 31 } 32 33 static bool cachefiles_mark_inode_in_use(struct cachefiles_object *object, 34 struct inode *inode) 35 { 36 bool can_use; 37 38 inode_lock(inode); 39 can_use = __cachefiles_mark_inode_in_use(object, inode); 40 inode_unlock(inode); 41 return can_use; 42 } 43 44 /* 45 * Unmark a backing inode. The caller must hold the inode lock. 46 */ 47 static void __cachefiles_unmark_inode_in_use(struct cachefiles_object *object, 48 struct inode *inode) 49 { 50 inode->i_flags &= ~S_KERNEL_FILE; 51 trace_cachefiles_mark_inactive(object, inode); 52 } 53 54 static void cachefiles_do_unmark_inode_in_use(struct cachefiles_object *object, 55 struct inode *inode) 56 { 57 inode_lock(inode); 58 __cachefiles_unmark_inode_in_use(object, inode); 59 inode_unlock(inode); 60 } 61 62 /* 63 * Unmark a backing inode and tell cachefilesd that there's something that can 64 * be culled. 65 */ 66 void cachefiles_unmark_inode_in_use(struct cachefiles_object *object, 67 struct file *file) 68 { 69 struct cachefiles_cache *cache = object->volume->cache; 70 struct inode *inode = file_inode(file); 71 72 cachefiles_do_unmark_inode_in_use(object, inode); 73 74 if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) { 75 atomic_long_add(inode->i_blocks, &cache->b_released); 76 if (atomic_inc_return(&cache->f_released)) 77 cachefiles_state_changed(cache); 78 } 79 } 80 81 /* 82 * get a subdirectory 83 */ 84 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache, 85 struct dentry *dir, 86 const char *dirname, 87 bool *_is_new) 88 { 89 struct dentry *subdir; 90 struct path path; 91 int ret; 92 93 _enter(",,%s", dirname); 94 95 /* search the current directory for the element name */ 96 inode_lock_nested(d_inode(dir), I_MUTEX_PARENT); 97 98 retry: 99 ret = cachefiles_inject_read_error(); 100 if (ret == 0) 101 subdir = lookup_one_len(dirname, dir, strlen(dirname)); 102 else 103 subdir = ERR_PTR(ret); 104 trace_cachefiles_lookup(NULL, dir, subdir); 105 if (IS_ERR(subdir)) { 106 trace_cachefiles_vfs_error(NULL, d_backing_inode(dir), 107 PTR_ERR(subdir), 108 cachefiles_trace_lookup_error); 109 if (PTR_ERR(subdir) == -ENOMEM) 110 goto nomem_d_alloc; 111 goto lookup_error; 112 } 113 114 _debug("subdir -> %pd %s", 115 subdir, d_backing_inode(subdir) ? "positive" : "negative"); 116 117 /* we need to create the subdir if it doesn't exist yet */ 118 if (d_is_negative(subdir)) { 119 ret = cachefiles_has_space(cache, 1, 0, 120 cachefiles_has_space_for_create); 121 if (ret < 0) 122 goto mkdir_error; 123 124 _debug("attempt mkdir"); 125 126 path.mnt = cache->mnt; 127 path.dentry = dir; 128 ret = security_path_mkdir(&path, subdir, 0700); 129 if (ret < 0) 130 goto mkdir_error; 131 ret = cachefiles_inject_write_error(); 132 if (ret == 0) 133 ret = vfs_mkdir(&init_user_ns, d_inode(dir), subdir, 0700); 134 if (ret < 0) { 135 trace_cachefiles_vfs_error(NULL, d_inode(dir), ret, 136 cachefiles_trace_mkdir_error); 137 goto mkdir_error; 138 } 139 trace_cachefiles_mkdir(dir, subdir); 140 141 if (unlikely(d_unhashed(subdir))) { 142 cachefiles_put_directory(subdir); 143 goto retry; 144 } 145 ASSERT(d_backing_inode(subdir)); 146 147 _debug("mkdir -> %pd{ino=%lu}", 148 subdir, d_backing_inode(subdir)->i_ino); 149 if (_is_new) 150 *_is_new = true; 151 } 152 153 /* Tell rmdir() it's not allowed to delete the subdir */ 154 inode_lock(d_inode(subdir)); 155 inode_unlock(d_inode(dir)); 156 157 if (!__cachefiles_mark_inode_in_use(NULL, d_inode(subdir))) { 158 pr_notice("cachefiles: Inode already in use: %pd (B=%lx)\n", 159 subdir, d_inode(subdir)->i_ino); 160 goto mark_error; 161 } 162 163 inode_unlock(d_inode(subdir)); 164 165 /* we need to make sure the subdir is a directory */ 166 ASSERT(d_backing_inode(subdir)); 167 168 if (!d_can_lookup(subdir)) { 169 pr_err("%s is not a directory\n", dirname); 170 ret = -EIO; 171 goto check_error; 172 } 173 174 ret = -EPERM; 175 if (!(d_backing_inode(subdir)->i_opflags & IOP_XATTR) || 176 !d_backing_inode(subdir)->i_op->lookup || 177 !d_backing_inode(subdir)->i_op->mkdir || 178 !d_backing_inode(subdir)->i_op->rename || 179 !d_backing_inode(subdir)->i_op->rmdir || 180 !d_backing_inode(subdir)->i_op->unlink) 181 goto check_error; 182 183 _leave(" = [%lu]", d_backing_inode(subdir)->i_ino); 184 return subdir; 185 186 check_error: 187 cachefiles_put_directory(subdir); 188 _leave(" = %d [check]", ret); 189 return ERR_PTR(ret); 190 191 mark_error: 192 inode_unlock(d_inode(subdir)); 193 dput(subdir); 194 return ERR_PTR(-EBUSY); 195 196 mkdir_error: 197 inode_unlock(d_inode(dir)); 198 dput(subdir); 199 pr_err("mkdir %s failed with error %d\n", dirname, ret); 200 return ERR_PTR(ret); 201 202 lookup_error: 203 inode_unlock(d_inode(dir)); 204 ret = PTR_ERR(subdir); 205 pr_err("Lookup %s failed with error %d\n", dirname, ret); 206 return ERR_PTR(ret); 207 208 nomem_d_alloc: 209 inode_unlock(d_inode(dir)); 210 _leave(" = -ENOMEM"); 211 return ERR_PTR(-ENOMEM); 212 } 213 214 /* 215 * Put a subdirectory. 216 */ 217 void cachefiles_put_directory(struct dentry *dir) 218 { 219 if (dir) { 220 cachefiles_do_unmark_inode_in_use(NULL, d_inode(dir)); 221 dput(dir); 222 } 223 } 224 225 /* 226 * Remove a regular file from the cache. 227 */ 228 static int cachefiles_unlink(struct cachefiles_cache *cache, 229 struct cachefiles_object *object, 230 struct dentry *dir, struct dentry *dentry, 231 enum fscache_why_object_killed why) 232 { 233 struct path path = { 234 .mnt = cache->mnt, 235 .dentry = dir, 236 }; 237 int ret; 238 239 trace_cachefiles_unlink(object, d_inode(dentry)->i_ino, why); 240 ret = security_path_unlink(&path, dentry); 241 if (ret < 0) { 242 cachefiles_io_error(cache, "Unlink security error"); 243 return ret; 244 } 245 246 ret = cachefiles_inject_remove_error(); 247 if (ret == 0) { 248 ret = vfs_unlink(&init_user_ns, d_backing_inode(dir), dentry, NULL); 249 if (ret == -EIO) 250 cachefiles_io_error(cache, "Unlink failed"); 251 } 252 if (ret != 0) 253 trace_cachefiles_vfs_error(object, d_backing_inode(dir), ret, 254 cachefiles_trace_unlink_error); 255 return ret; 256 } 257 258 /* 259 * Delete an object representation from the cache 260 * - File backed objects are unlinked 261 * - Directory backed objects are stuffed into the graveyard for userspace to 262 * delete 263 */ 264 int cachefiles_bury_object(struct cachefiles_cache *cache, 265 struct cachefiles_object *object, 266 struct dentry *dir, 267 struct dentry *rep, 268 enum fscache_why_object_killed why) 269 { 270 struct dentry *grave, *trap; 271 struct path path, path_to_graveyard; 272 char nbuffer[8 + 8 + 1]; 273 int ret; 274 275 _enter(",'%pd','%pd'", dir, rep); 276 277 if (rep->d_parent != dir) { 278 inode_unlock(d_inode(dir)); 279 _leave(" = -ESTALE"); 280 return -ESTALE; 281 } 282 283 /* non-directories can just be unlinked */ 284 if (!d_is_dir(rep)) { 285 dget(rep); /* Stop the dentry being negated if it's only pinned 286 * by a file struct. 287 */ 288 ret = cachefiles_unlink(cache, object, dir, rep, why); 289 dput(rep); 290 291 inode_unlock(d_inode(dir)); 292 _leave(" = %d", ret); 293 return ret; 294 } 295 296 /* directories have to be moved to the graveyard */ 297 _debug("move stale object to graveyard"); 298 inode_unlock(d_inode(dir)); 299 300 try_again: 301 /* first step is to make up a grave dentry in the graveyard */ 302 sprintf(nbuffer, "%08x%08x", 303 (uint32_t) ktime_get_real_seconds(), 304 (uint32_t) atomic_inc_return(&cache->gravecounter)); 305 306 /* do the multiway lock magic */ 307 trap = lock_rename(cache->graveyard, dir); 308 309 /* do some checks before getting the grave dentry */ 310 if (rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) { 311 /* the entry was probably culled when we dropped the parent dir 312 * lock */ 313 unlock_rename(cache->graveyard, dir); 314 _leave(" = 0 [culled?]"); 315 return 0; 316 } 317 318 if (!d_can_lookup(cache->graveyard)) { 319 unlock_rename(cache->graveyard, dir); 320 cachefiles_io_error(cache, "Graveyard no longer a directory"); 321 return -EIO; 322 } 323 324 if (trap == rep) { 325 unlock_rename(cache->graveyard, dir); 326 cachefiles_io_error(cache, "May not make directory loop"); 327 return -EIO; 328 } 329 330 if (d_mountpoint(rep)) { 331 unlock_rename(cache->graveyard, dir); 332 cachefiles_io_error(cache, "Mountpoint in cache"); 333 return -EIO; 334 } 335 336 grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer)); 337 if (IS_ERR(grave)) { 338 unlock_rename(cache->graveyard, dir); 339 trace_cachefiles_vfs_error(object, d_inode(cache->graveyard), 340 PTR_ERR(grave), 341 cachefiles_trace_lookup_error); 342 343 if (PTR_ERR(grave) == -ENOMEM) { 344 _leave(" = -ENOMEM"); 345 return -ENOMEM; 346 } 347 348 cachefiles_io_error(cache, "Lookup error %ld", PTR_ERR(grave)); 349 return -EIO; 350 } 351 352 if (d_is_positive(grave)) { 353 unlock_rename(cache->graveyard, dir); 354 dput(grave); 355 grave = NULL; 356 cond_resched(); 357 goto try_again; 358 } 359 360 if (d_mountpoint(grave)) { 361 unlock_rename(cache->graveyard, dir); 362 dput(grave); 363 cachefiles_io_error(cache, "Mountpoint in graveyard"); 364 return -EIO; 365 } 366 367 /* target should not be an ancestor of source */ 368 if (trap == grave) { 369 unlock_rename(cache->graveyard, dir); 370 dput(grave); 371 cachefiles_io_error(cache, "May not make directory loop"); 372 return -EIO; 373 } 374 375 /* attempt the rename */ 376 path.mnt = cache->mnt; 377 path.dentry = dir; 378 path_to_graveyard.mnt = cache->mnt; 379 path_to_graveyard.dentry = cache->graveyard; 380 ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0); 381 if (ret < 0) { 382 cachefiles_io_error(cache, "Rename security error %d", ret); 383 } else { 384 struct renamedata rd = { 385 .old_mnt_userns = &init_user_ns, 386 .old_dir = d_inode(dir), 387 .old_dentry = rep, 388 .new_mnt_userns = &init_user_ns, 389 .new_dir = d_inode(cache->graveyard), 390 .new_dentry = grave, 391 }; 392 trace_cachefiles_rename(object, d_inode(rep)->i_ino, why); 393 ret = cachefiles_inject_read_error(); 394 if (ret == 0) 395 ret = vfs_rename(&rd); 396 if (ret != 0) 397 trace_cachefiles_vfs_error(object, d_inode(dir), ret, 398 cachefiles_trace_rename_error); 399 if (ret != 0 && ret != -ENOMEM) 400 cachefiles_io_error(cache, 401 "Rename failed with error %d", ret); 402 } 403 404 __cachefiles_unmark_inode_in_use(object, d_inode(rep)); 405 unlock_rename(cache->graveyard, dir); 406 dput(grave); 407 _leave(" = 0"); 408 return 0; 409 } 410 411 /* 412 * Delete a cache file. 413 */ 414 int cachefiles_delete_object(struct cachefiles_object *object, 415 enum fscache_why_object_killed why) 416 { 417 struct cachefiles_volume *volume = object->volume; 418 struct dentry *dentry = object->file->f_path.dentry; 419 struct dentry *fan = volume->fanout[(u8)object->cookie->key_hash]; 420 int ret; 421 422 _enter(",OBJ%x{%pD}", object->debug_id, object->file); 423 424 /* Stop the dentry being negated if it's only pinned by a file struct. */ 425 dget(dentry); 426 427 inode_lock_nested(d_backing_inode(fan), I_MUTEX_PARENT); 428 ret = cachefiles_unlink(volume->cache, object, fan, dentry, why); 429 inode_unlock(d_backing_inode(fan)); 430 dput(dentry); 431 return ret; 432 } 433 434 /* 435 * Create a temporary file and leave it unattached and un-xattr'd until the 436 * time comes to discard the object from memory. 437 */ 438 struct file *cachefiles_create_tmpfile(struct cachefiles_object *object) 439 { 440 struct cachefiles_volume *volume = object->volume; 441 struct cachefiles_cache *cache = volume->cache; 442 const struct cred *saved_cred; 443 struct dentry *fan = volume->fanout[(u8)object->cookie->key_hash]; 444 struct file *file; 445 struct path path; 446 uint64_t ni_size; 447 long ret; 448 449 450 cachefiles_begin_secure(cache, &saved_cred); 451 452 path.mnt = cache->mnt; 453 ret = cachefiles_inject_write_error(); 454 if (ret == 0) { 455 path.dentry = vfs_tmpfile(&init_user_ns, fan, S_IFREG, O_RDWR); 456 ret = PTR_ERR_OR_ZERO(path.dentry); 457 } 458 if (ret) { 459 trace_cachefiles_vfs_error(object, d_inode(fan), ret, 460 cachefiles_trace_tmpfile_error); 461 if (ret == -EIO) 462 cachefiles_io_error_obj(object, "Failed to create tmpfile"); 463 goto err; 464 } 465 466 trace_cachefiles_tmpfile(object, d_backing_inode(path.dentry)); 467 468 /* This is a newly created file with no other possible user */ 469 if (!cachefiles_mark_inode_in_use(object, d_inode(path.dentry))) 470 WARN_ON(1); 471 472 ret = cachefiles_ondemand_init_object(object); 473 if (ret < 0) 474 goto err_unuse; 475 476 ni_size = object->cookie->object_size; 477 ni_size = round_up(ni_size, CACHEFILES_DIO_BLOCK_SIZE); 478 479 if (ni_size > 0) { 480 trace_cachefiles_trunc(object, d_backing_inode(path.dentry), 0, ni_size, 481 cachefiles_trunc_expand_tmpfile); 482 ret = cachefiles_inject_write_error(); 483 if (ret == 0) 484 ret = vfs_truncate(&path, ni_size); 485 if (ret < 0) { 486 trace_cachefiles_vfs_error( 487 object, d_backing_inode(path.dentry), ret, 488 cachefiles_trace_trunc_error); 489 goto err_unuse; 490 } 491 } 492 493 file = open_with_fake_path(&path, O_RDWR | O_LARGEFILE | O_DIRECT, 494 d_backing_inode(path.dentry), cache->cache_cred); 495 ret = PTR_ERR(file); 496 if (IS_ERR(file)) { 497 trace_cachefiles_vfs_error(object, d_backing_inode(path.dentry), 498 ret, cachefiles_trace_open_error); 499 goto err_unuse; 500 } 501 ret = -EINVAL; 502 if (unlikely(!file->f_op->read_iter) || 503 unlikely(!file->f_op->write_iter)) { 504 fput(file); 505 pr_notice("Cache does not support read_iter and write_iter\n"); 506 goto err_unuse; 507 } 508 dput(path.dentry); 509 out: 510 cachefiles_end_secure(cache, saved_cred); 511 return file; 512 513 err_unuse: 514 cachefiles_do_unmark_inode_in_use(object, d_inode(path.dentry)); 515 dput(path.dentry); 516 err: 517 file = ERR_PTR(ret); 518 goto out; 519 } 520 521 /* 522 * Create a new file. 523 */ 524 static bool cachefiles_create_file(struct cachefiles_object *object) 525 { 526 struct file *file; 527 int ret; 528 529 ret = cachefiles_has_space(object->volume->cache, 1, 0, 530 cachefiles_has_space_for_create); 531 if (ret < 0) 532 return false; 533 534 file = cachefiles_create_tmpfile(object); 535 if (IS_ERR(file)) 536 return false; 537 538 set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags); 539 set_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); 540 _debug("create -> %pD{ino=%lu}", file, file_inode(file)->i_ino); 541 object->file = file; 542 return true; 543 } 544 545 /* 546 * Open an existing file, checking its attributes and replacing it if it is 547 * stale. 548 */ 549 static bool cachefiles_open_file(struct cachefiles_object *object, 550 struct dentry *dentry) 551 { 552 struct cachefiles_cache *cache = object->volume->cache; 553 struct file *file; 554 struct path path; 555 int ret; 556 557 _enter("%pd", dentry); 558 559 if (!cachefiles_mark_inode_in_use(object, d_inode(dentry))) { 560 pr_notice("cachefiles: Inode already in use: %pd (B=%lx)\n", 561 dentry, d_inode(dentry)->i_ino); 562 return false; 563 } 564 565 /* We need to open a file interface onto a data file now as we can't do 566 * it on demand because writeback called from do_exit() sees 567 * current->fs == NULL - which breaks d_path() called from ext4 open. 568 */ 569 path.mnt = cache->mnt; 570 path.dentry = dentry; 571 file = open_with_fake_path(&path, O_RDWR | O_LARGEFILE | O_DIRECT, 572 d_backing_inode(dentry), cache->cache_cred); 573 if (IS_ERR(file)) { 574 trace_cachefiles_vfs_error(object, d_backing_inode(dentry), 575 PTR_ERR(file), 576 cachefiles_trace_open_error); 577 goto error; 578 } 579 580 if (unlikely(!file->f_op->read_iter) || 581 unlikely(!file->f_op->write_iter)) { 582 pr_notice("Cache does not support read_iter and write_iter\n"); 583 goto error_fput; 584 } 585 _debug("file -> %pd positive", dentry); 586 587 ret = cachefiles_ondemand_init_object(object); 588 if (ret < 0) 589 goto error_fput; 590 591 ret = cachefiles_check_auxdata(object, file); 592 if (ret < 0) 593 goto check_failed; 594 595 object->file = file; 596 597 /* Always update the atime on an object we've just looked up (this is 598 * used to keep track of culling, and atimes are only updated by read, 599 * write and readdir but not lookup or open). 600 */ 601 touch_atime(&file->f_path); 602 dput(dentry); 603 return true; 604 605 check_failed: 606 fscache_cookie_lookup_negative(object->cookie); 607 cachefiles_unmark_inode_in_use(object, file); 608 fput(file); 609 dput(dentry); 610 if (ret == -ESTALE) 611 return cachefiles_create_file(object); 612 return false; 613 614 error_fput: 615 fput(file); 616 error: 617 cachefiles_do_unmark_inode_in_use(object, d_inode(dentry)); 618 dput(dentry); 619 return false; 620 } 621 622 /* 623 * walk from the parent object to the child object through the backing 624 * filesystem, creating directories as we go 625 */ 626 bool cachefiles_look_up_object(struct cachefiles_object *object) 627 { 628 struct cachefiles_volume *volume = object->volume; 629 struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash]; 630 int ret; 631 632 _enter("OBJ%x,%s,", object->debug_id, object->d_name); 633 634 /* Look up path "cache/vol/fanout/file". */ 635 ret = cachefiles_inject_read_error(); 636 if (ret == 0) 637 dentry = lookup_positive_unlocked(object->d_name, fan, 638 object->d_name_len); 639 else 640 dentry = ERR_PTR(ret); 641 trace_cachefiles_lookup(object, fan, dentry); 642 if (IS_ERR(dentry)) { 643 if (dentry == ERR_PTR(-ENOENT)) 644 goto new_file; 645 if (dentry == ERR_PTR(-EIO)) 646 cachefiles_io_error_obj(object, "Lookup failed"); 647 return false; 648 } 649 650 if (!d_is_reg(dentry)) { 651 pr_err("%pd is not a file\n", dentry); 652 inode_lock_nested(d_inode(fan), I_MUTEX_PARENT); 653 ret = cachefiles_bury_object(volume->cache, object, fan, dentry, 654 FSCACHE_OBJECT_IS_WEIRD); 655 dput(dentry); 656 if (ret < 0) 657 return false; 658 goto new_file; 659 } 660 661 if (!cachefiles_open_file(object, dentry)) 662 return false; 663 664 _leave(" = t [%lu]", file_inode(object->file)->i_ino); 665 return true; 666 667 new_file: 668 fscache_cookie_lookup_negative(object->cookie); 669 return cachefiles_create_file(object); 670 } 671 672 /* 673 * Attempt to link a temporary file into its rightful place in the cache. 674 */ 675 bool cachefiles_commit_tmpfile(struct cachefiles_cache *cache, 676 struct cachefiles_object *object) 677 { 678 struct cachefiles_volume *volume = object->volume; 679 struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash]; 680 bool success = false; 681 int ret; 682 683 _enter(",%pD", object->file); 684 685 inode_lock_nested(d_inode(fan), I_MUTEX_PARENT); 686 ret = cachefiles_inject_read_error(); 687 if (ret == 0) 688 dentry = lookup_one_len(object->d_name, fan, object->d_name_len); 689 else 690 dentry = ERR_PTR(ret); 691 if (IS_ERR(dentry)) { 692 trace_cachefiles_vfs_error(object, d_inode(fan), PTR_ERR(dentry), 693 cachefiles_trace_lookup_error); 694 _debug("lookup fail %ld", PTR_ERR(dentry)); 695 goto out_unlock; 696 } 697 698 if (!d_is_negative(dentry)) { 699 if (d_backing_inode(dentry) == file_inode(object->file)) { 700 success = true; 701 goto out_dput; 702 } 703 704 ret = cachefiles_unlink(volume->cache, object, fan, dentry, 705 FSCACHE_OBJECT_IS_STALE); 706 if (ret < 0) 707 goto out_dput; 708 709 dput(dentry); 710 ret = cachefiles_inject_read_error(); 711 if (ret == 0) 712 dentry = lookup_one_len(object->d_name, fan, object->d_name_len); 713 else 714 dentry = ERR_PTR(ret); 715 if (IS_ERR(dentry)) { 716 trace_cachefiles_vfs_error(object, d_inode(fan), PTR_ERR(dentry), 717 cachefiles_trace_lookup_error); 718 _debug("lookup fail %ld", PTR_ERR(dentry)); 719 goto out_unlock; 720 } 721 } 722 723 ret = cachefiles_inject_read_error(); 724 if (ret == 0) 725 ret = vfs_link(object->file->f_path.dentry, &init_user_ns, 726 d_inode(fan), dentry, NULL); 727 if (ret < 0) { 728 trace_cachefiles_vfs_error(object, d_inode(fan), ret, 729 cachefiles_trace_link_error); 730 _debug("link fail %d", ret); 731 } else { 732 trace_cachefiles_link(object, file_inode(object->file)); 733 spin_lock(&object->lock); 734 /* TODO: Do we want to switch the file pointer to the new dentry? */ 735 clear_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); 736 spin_unlock(&object->lock); 737 success = true; 738 } 739 740 out_dput: 741 dput(dentry); 742 out_unlock: 743 inode_unlock(d_inode(fan)); 744 _leave(" = %u", success); 745 return success; 746 } 747 748 /* 749 * Look up an inode to be checked or culled. Return -EBUSY if the inode is 750 * marked in use. 751 */ 752 static struct dentry *cachefiles_lookup_for_cull(struct cachefiles_cache *cache, 753 struct dentry *dir, 754 char *filename) 755 { 756 struct dentry *victim; 757 int ret = -ENOENT; 758 759 inode_lock_nested(d_inode(dir), I_MUTEX_PARENT); 760 761 victim = lookup_one_len(filename, dir, strlen(filename)); 762 if (IS_ERR(victim)) 763 goto lookup_error; 764 if (d_is_negative(victim)) 765 goto lookup_put; 766 if (d_inode(victim)->i_flags & S_KERNEL_FILE) 767 goto lookup_busy; 768 return victim; 769 770 lookup_busy: 771 ret = -EBUSY; 772 lookup_put: 773 inode_unlock(d_inode(dir)); 774 dput(victim); 775 return ERR_PTR(ret); 776 777 lookup_error: 778 inode_unlock(d_inode(dir)); 779 ret = PTR_ERR(victim); 780 if (ret == -ENOENT) 781 return ERR_PTR(-ESTALE); /* Probably got retired by the netfs */ 782 783 if (ret == -EIO) { 784 cachefiles_io_error(cache, "Lookup failed"); 785 } else if (ret != -ENOMEM) { 786 pr_err("Internal error: %d\n", ret); 787 ret = -EIO; 788 } 789 790 return ERR_PTR(ret); 791 } 792 793 /* 794 * Cull an object if it's not in use 795 * - called only by cache manager daemon 796 */ 797 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir, 798 char *filename) 799 { 800 struct dentry *victim; 801 struct inode *inode; 802 int ret; 803 804 _enter(",%pd/,%s", dir, filename); 805 806 victim = cachefiles_lookup_for_cull(cache, dir, filename); 807 if (IS_ERR(victim)) 808 return PTR_ERR(victim); 809 810 /* check to see if someone is using this object */ 811 inode = d_inode(victim); 812 inode_lock(inode); 813 if (inode->i_flags & S_KERNEL_FILE) { 814 ret = -EBUSY; 815 } else { 816 /* Stop the cache from picking it back up */ 817 inode->i_flags |= S_KERNEL_FILE; 818 ret = 0; 819 } 820 inode_unlock(inode); 821 if (ret < 0) 822 goto error_unlock; 823 824 ret = cachefiles_bury_object(cache, NULL, dir, victim, 825 FSCACHE_OBJECT_WAS_CULLED); 826 if (ret < 0) 827 goto error; 828 829 fscache_count_culled(); 830 dput(victim); 831 _leave(" = 0"); 832 return 0; 833 834 error_unlock: 835 inode_unlock(d_inode(dir)); 836 error: 837 dput(victim); 838 if (ret == -ENOENT) 839 return -ESTALE; /* Probably got retired by the netfs */ 840 841 if (ret != -ENOMEM) { 842 pr_err("Internal error: %d\n", ret); 843 ret = -EIO; 844 } 845 846 _leave(" = %d", ret); 847 return ret; 848 } 849 850 /* 851 * Find out if an object is in use or not 852 * - called only by cache manager daemon 853 * - returns -EBUSY or 0 to indicate whether an object is in use or not 854 */ 855 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir, 856 char *filename) 857 { 858 struct dentry *victim; 859 int ret = 0; 860 861 victim = cachefiles_lookup_for_cull(cache, dir, filename); 862 if (IS_ERR(victim)) 863 return PTR_ERR(victim); 864 865 inode_unlock(d_inode(dir)); 866 dput(victim); 867 return ret; 868 } 869