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(&nop_mnt_idmap, &QSTR(dirname), dir); 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 subdir = vfs_mkdir(&nop_mnt_idmap, d_inode(dir), subdir, 0700); 134 else 135 subdir = ERR_PTR(ret); 136 if (IS_ERR(subdir)) { 137 trace_cachefiles_vfs_error(NULL, d_inode(dir), ret, 138 cachefiles_trace_mkdir_error); 139 goto mkdir_error; 140 } 141 trace_cachefiles_mkdir(dir, subdir); 142 143 if (unlikely(d_unhashed(subdir) || d_is_negative(subdir))) { 144 dput(subdir); 145 goto retry; 146 } 147 ASSERT(d_backing_inode(subdir)); 148 149 _debug("mkdir -> %pd{ino=%lu}", 150 subdir, d_backing_inode(subdir)->i_ino); 151 if (_is_new) 152 *_is_new = true; 153 } 154 155 /* Tell rmdir() it's not allowed to delete the subdir */ 156 inode_lock(d_inode(subdir)); 157 inode_unlock(d_inode(dir)); 158 159 if (!__cachefiles_mark_inode_in_use(NULL, d_inode(subdir))) { 160 pr_notice("cachefiles: Inode already in use: %pd (B=%lx)\n", 161 subdir, d_inode(subdir)->i_ino); 162 goto mark_error; 163 } 164 165 inode_unlock(d_inode(subdir)); 166 167 /* we need to make sure the subdir is a directory */ 168 ASSERT(d_backing_inode(subdir)); 169 170 if (!d_can_lookup(subdir)) { 171 pr_err("%s is not a directory\n", dirname); 172 ret = -EIO; 173 goto check_error; 174 } 175 176 ret = -EPERM; 177 if (!(d_backing_inode(subdir)->i_opflags & IOP_XATTR) || 178 !d_backing_inode(subdir)->i_op->lookup || 179 !d_backing_inode(subdir)->i_op->mkdir || 180 !d_backing_inode(subdir)->i_op->rename || 181 !d_backing_inode(subdir)->i_op->rmdir || 182 !d_backing_inode(subdir)->i_op->unlink) 183 goto check_error; 184 185 _leave(" = [%lu]", d_backing_inode(subdir)->i_ino); 186 return subdir; 187 188 check_error: 189 cachefiles_put_directory(subdir); 190 _leave(" = %d [check]", ret); 191 return ERR_PTR(ret); 192 193 mark_error: 194 inode_unlock(d_inode(subdir)); 195 dput(subdir); 196 return ERR_PTR(-EBUSY); 197 198 mkdir_error: 199 inode_unlock(d_inode(dir)); 200 if (!IS_ERR(subdir)) 201 dput(subdir); 202 pr_err("mkdir %s failed with error %d\n", dirname, ret); 203 return ERR_PTR(ret); 204 205 lookup_error: 206 inode_unlock(d_inode(dir)); 207 ret = PTR_ERR(subdir); 208 pr_err("Lookup %s failed with error %d\n", dirname, ret); 209 return ERR_PTR(ret); 210 211 nomem_d_alloc: 212 inode_unlock(d_inode(dir)); 213 _leave(" = -ENOMEM"); 214 return ERR_PTR(-ENOMEM); 215 } 216 217 /* 218 * Put a subdirectory. 219 */ 220 void cachefiles_put_directory(struct dentry *dir) 221 { 222 if (dir) { 223 cachefiles_do_unmark_inode_in_use(NULL, d_inode(dir)); 224 dput(dir); 225 } 226 } 227 228 /* 229 * Remove a regular file from the cache. 230 */ 231 static int cachefiles_unlink(struct cachefiles_cache *cache, 232 struct cachefiles_object *object, 233 struct dentry *dir, struct dentry *dentry, 234 enum fscache_why_object_killed why) 235 { 236 struct path path = { 237 .mnt = cache->mnt, 238 .dentry = dir, 239 }; 240 int ret; 241 242 trace_cachefiles_unlink(object, d_inode(dentry)->i_ino, why); 243 ret = security_path_unlink(&path, dentry); 244 if (ret < 0) { 245 cachefiles_io_error(cache, "Unlink security error"); 246 return ret; 247 } 248 249 ret = cachefiles_inject_remove_error(); 250 if (ret == 0) { 251 ret = vfs_unlink(&nop_mnt_idmap, d_backing_inode(dir), dentry, NULL); 252 if (ret == -EIO) 253 cachefiles_io_error(cache, "Unlink failed"); 254 } 255 if (ret != 0) 256 trace_cachefiles_vfs_error(object, d_backing_inode(dir), ret, 257 cachefiles_trace_unlink_error); 258 return ret; 259 } 260 261 /* 262 * Delete an object representation from the cache 263 * - File backed objects are unlinked 264 * - Directory backed objects are stuffed into the graveyard for userspace to 265 * delete 266 */ 267 int cachefiles_bury_object(struct cachefiles_cache *cache, 268 struct cachefiles_object *object, 269 struct dentry *dir, 270 struct dentry *rep, 271 enum fscache_why_object_killed why) 272 { 273 struct dentry *grave, *trap; 274 struct path path, path_to_graveyard; 275 char nbuffer[8 + 8 + 1]; 276 int ret; 277 278 _enter(",'%pd','%pd'", dir, rep); 279 280 if (rep->d_parent != dir) { 281 inode_unlock(d_inode(dir)); 282 _leave(" = -ESTALE"); 283 return -ESTALE; 284 } 285 286 /* non-directories can just be unlinked */ 287 if (!d_is_dir(rep)) { 288 dget(rep); /* Stop the dentry being negated if it's only pinned 289 * by a file struct. 290 */ 291 ret = cachefiles_unlink(cache, object, dir, rep, why); 292 dput(rep); 293 294 inode_unlock(d_inode(dir)); 295 _leave(" = %d", ret); 296 return ret; 297 } 298 299 /* directories have to be moved to the graveyard */ 300 _debug("move stale object to graveyard"); 301 inode_unlock(d_inode(dir)); 302 303 try_again: 304 /* first step is to make up a grave dentry in the graveyard */ 305 sprintf(nbuffer, "%08x%08x", 306 (uint32_t) ktime_get_real_seconds(), 307 (uint32_t) atomic_inc_return(&cache->gravecounter)); 308 309 /* do the multiway lock magic */ 310 trap = lock_rename(cache->graveyard, dir); 311 if (IS_ERR(trap)) 312 return PTR_ERR(trap); 313 314 /* do some checks before getting the grave dentry */ 315 if (rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) { 316 /* the entry was probably culled when we dropped the parent dir 317 * lock */ 318 unlock_rename(cache->graveyard, dir); 319 _leave(" = 0 [culled?]"); 320 return 0; 321 } 322 323 if (!d_can_lookup(cache->graveyard)) { 324 unlock_rename(cache->graveyard, dir); 325 cachefiles_io_error(cache, "Graveyard no longer a directory"); 326 return -EIO; 327 } 328 329 if (trap == rep) { 330 unlock_rename(cache->graveyard, dir); 331 cachefiles_io_error(cache, "May not make directory loop"); 332 return -EIO; 333 } 334 335 if (d_mountpoint(rep)) { 336 unlock_rename(cache->graveyard, dir); 337 cachefiles_io_error(cache, "Mountpoint in cache"); 338 return -EIO; 339 } 340 341 grave = lookup_one(&nop_mnt_idmap, &QSTR(nbuffer), cache->graveyard); 342 if (IS_ERR(grave)) { 343 unlock_rename(cache->graveyard, dir); 344 trace_cachefiles_vfs_error(object, d_inode(cache->graveyard), 345 PTR_ERR(grave), 346 cachefiles_trace_lookup_error); 347 348 if (PTR_ERR(grave) == -ENOMEM) { 349 _leave(" = -ENOMEM"); 350 return -ENOMEM; 351 } 352 353 cachefiles_io_error(cache, "Lookup error %ld", PTR_ERR(grave)); 354 return -EIO; 355 } 356 357 if (d_is_positive(grave)) { 358 unlock_rename(cache->graveyard, dir); 359 dput(grave); 360 grave = NULL; 361 cond_resched(); 362 goto try_again; 363 } 364 365 if (d_mountpoint(grave)) { 366 unlock_rename(cache->graveyard, dir); 367 dput(grave); 368 cachefiles_io_error(cache, "Mountpoint in graveyard"); 369 return -EIO; 370 } 371 372 /* target should not be an ancestor of source */ 373 if (trap == grave) { 374 unlock_rename(cache->graveyard, dir); 375 dput(grave); 376 cachefiles_io_error(cache, "May not make directory loop"); 377 return -EIO; 378 } 379 380 /* attempt the rename */ 381 path.mnt = cache->mnt; 382 path.dentry = dir; 383 path_to_graveyard.mnt = cache->mnt; 384 path_to_graveyard.dentry = cache->graveyard; 385 ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0); 386 if (ret < 0) { 387 cachefiles_io_error(cache, "Rename security error %d", ret); 388 } else { 389 struct renamedata rd = { 390 .mnt_idmap = &nop_mnt_idmap, 391 .old_parent = dir, 392 .old_dentry = rep, 393 .new_parent = cache->graveyard, 394 .new_dentry = grave, 395 }; 396 trace_cachefiles_rename(object, d_inode(rep)->i_ino, why); 397 ret = cachefiles_inject_read_error(); 398 if (ret == 0) 399 ret = vfs_rename(&rd); 400 if (ret != 0) 401 trace_cachefiles_vfs_error(object, d_inode(dir), ret, 402 cachefiles_trace_rename_error); 403 if (ret != 0 && ret != -ENOMEM) 404 cachefiles_io_error(cache, 405 "Rename failed with error %d", ret); 406 } 407 408 __cachefiles_unmark_inode_in_use(object, d_inode(rep)); 409 unlock_rename(cache->graveyard, dir); 410 dput(grave); 411 _leave(" = 0"); 412 return 0; 413 } 414 415 /* 416 * Delete a cache file. 417 */ 418 int cachefiles_delete_object(struct cachefiles_object *object, 419 enum fscache_why_object_killed why) 420 { 421 struct cachefiles_volume *volume = object->volume; 422 struct dentry *dentry = object->file->f_path.dentry; 423 struct dentry *fan = volume->fanout[(u8)object->cookie->key_hash]; 424 int ret; 425 426 _enter(",OBJ%x{%pD}", object->debug_id, object->file); 427 428 /* Stop the dentry being negated if it's only pinned by a file struct. */ 429 dget(dentry); 430 431 inode_lock_nested(d_backing_inode(fan), I_MUTEX_PARENT); 432 ret = cachefiles_unlink(volume->cache, object, fan, dentry, why); 433 inode_unlock(d_backing_inode(fan)); 434 dput(dentry); 435 return ret; 436 } 437 438 /* 439 * Create a temporary file and leave it unattached and un-xattr'd until the 440 * time comes to discard the object from memory. 441 */ 442 struct file *cachefiles_create_tmpfile(struct cachefiles_object *object) 443 { 444 struct cachefiles_volume *volume = object->volume; 445 struct cachefiles_cache *cache = volume->cache; 446 const struct cred *saved_cred; 447 struct dentry *fan = volume->fanout[(u8)object->cookie->key_hash]; 448 struct file *file; 449 const struct path parentpath = { .mnt = cache->mnt, .dentry = fan }; 450 uint64_t ni_size; 451 long ret; 452 453 454 cachefiles_begin_secure(cache, &saved_cred); 455 456 ret = cachefiles_inject_write_error(); 457 if (ret == 0) { 458 file = kernel_tmpfile_open(&nop_mnt_idmap, &parentpath, 459 S_IFREG | 0600, 460 O_RDWR | O_LARGEFILE | O_DIRECT, 461 cache->cache_cred); 462 ret = PTR_ERR_OR_ZERO(file); 463 } 464 if (ret) { 465 trace_cachefiles_vfs_error(object, d_inode(fan), ret, 466 cachefiles_trace_tmpfile_error); 467 if (ret == -EIO) 468 cachefiles_io_error_obj(object, "Failed to create tmpfile"); 469 goto err; 470 } 471 472 trace_cachefiles_tmpfile(object, file_inode(file)); 473 474 /* This is a newly created file with no other possible user */ 475 if (!cachefiles_mark_inode_in_use(object, file_inode(file))) 476 WARN_ON(1); 477 478 ret = cachefiles_ondemand_init_object(object); 479 if (ret < 0) 480 goto err_unuse; 481 482 ni_size = object->cookie->object_size; 483 ni_size = round_up(ni_size, CACHEFILES_DIO_BLOCK_SIZE); 484 485 if (ni_size > 0) { 486 trace_cachefiles_trunc(object, file_inode(file), 0, ni_size, 487 cachefiles_trunc_expand_tmpfile); 488 ret = cachefiles_inject_write_error(); 489 if (ret == 0) 490 ret = vfs_truncate(&file->f_path, ni_size); 491 if (ret < 0) { 492 trace_cachefiles_vfs_error( 493 object, file_inode(file), ret, 494 cachefiles_trace_trunc_error); 495 goto err_unuse; 496 } 497 } 498 499 ret = -EINVAL; 500 if (unlikely(!file->f_op->read_iter) || 501 unlikely(!file->f_op->write_iter)) { 502 fput(file); 503 pr_notice("Cache does not support read_iter and write_iter\n"); 504 goto err_unuse; 505 } 506 out: 507 cachefiles_end_secure(cache, saved_cred); 508 return file; 509 510 err_unuse: 511 cachefiles_do_unmark_inode_in_use(object, file_inode(file)); 512 fput(file); 513 err: 514 file = ERR_PTR(ret); 515 goto out; 516 } 517 518 /* 519 * Create a new file. 520 */ 521 static bool cachefiles_create_file(struct cachefiles_object *object) 522 { 523 struct file *file; 524 int ret; 525 526 ret = cachefiles_has_space(object->volume->cache, 1, 0, 527 cachefiles_has_space_for_create); 528 if (ret < 0) 529 return false; 530 531 file = cachefiles_create_tmpfile(object); 532 if (IS_ERR(file)) 533 return false; 534 535 set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags); 536 set_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); 537 _debug("create -> %pD{ino=%lu}", file, file_inode(file)->i_ino); 538 object->file = file; 539 return true; 540 } 541 542 /* 543 * Open an existing file, checking its attributes and replacing it if it is 544 * stale. 545 */ 546 static bool cachefiles_open_file(struct cachefiles_object *object, 547 struct dentry *dentry) 548 { 549 struct cachefiles_cache *cache = object->volume->cache; 550 struct file *file; 551 struct path path; 552 int ret; 553 554 _enter("%pd", dentry); 555 556 if (!cachefiles_mark_inode_in_use(object, d_inode(dentry))) { 557 pr_notice("cachefiles: Inode already in use: %pd (B=%lx)\n", 558 dentry, d_inode(dentry)->i_ino); 559 return false; 560 } 561 562 /* We need to open a file interface onto a data file now as we can't do 563 * it on demand because writeback called from do_exit() sees 564 * current->fs == NULL - which breaks d_path() called from ext4 open. 565 */ 566 path.mnt = cache->mnt; 567 path.dentry = dentry; 568 file = kernel_file_open(&path, O_RDWR | O_LARGEFILE | O_DIRECT, cache->cache_cred); 569 if (IS_ERR(file)) { 570 trace_cachefiles_vfs_error(object, d_backing_inode(dentry), 571 PTR_ERR(file), 572 cachefiles_trace_open_error); 573 goto error; 574 } 575 576 if (unlikely(!file->f_op->read_iter) || 577 unlikely(!file->f_op->write_iter)) { 578 pr_notice("Cache does not support read_iter and write_iter\n"); 579 goto error_fput; 580 } 581 _debug("file -> %pd positive", dentry); 582 583 ret = cachefiles_ondemand_init_object(object); 584 if (ret < 0) 585 goto error_fput; 586 587 ret = cachefiles_check_auxdata(object, file); 588 if (ret < 0) 589 goto check_failed; 590 591 clear_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &object->cookie->flags); 592 593 object->file = file; 594 595 /* Always update the atime on an object we've just looked up (this is 596 * used to keep track of culling, and atimes are only updated by read, 597 * write and readdir but not lookup or open). 598 */ 599 touch_atime(&file->f_path); 600 return true; 601 602 check_failed: 603 fscache_cookie_lookup_negative(object->cookie); 604 cachefiles_unmark_inode_in_use(object, file); 605 fput(file); 606 if (ret == -ESTALE) 607 return cachefiles_create_file(object); 608 return false; 609 610 error_fput: 611 fput(file); 612 error: 613 cachefiles_do_unmark_inode_in_use(object, d_inode(dentry)); 614 return false; 615 } 616 617 /* 618 * walk from the parent object to the child object through the backing 619 * filesystem, creating directories as we go 620 */ 621 bool cachefiles_look_up_object(struct cachefiles_object *object) 622 { 623 struct cachefiles_volume *volume = object->volume; 624 struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash]; 625 int ret; 626 627 _enter("OBJ%x,%s,", object->debug_id, object->d_name); 628 629 /* Look up path "cache/vol/fanout/file". */ 630 ret = cachefiles_inject_read_error(); 631 if (ret == 0) 632 dentry = lookup_one_positive_unlocked(&nop_mnt_idmap, 633 &QSTR(object->d_name), fan); 634 else 635 dentry = ERR_PTR(ret); 636 trace_cachefiles_lookup(object, fan, dentry); 637 if (IS_ERR(dentry)) { 638 if (dentry == ERR_PTR(-ENOENT)) 639 goto new_file; 640 if (dentry == ERR_PTR(-EIO)) 641 cachefiles_io_error_obj(object, "Lookup failed"); 642 return false; 643 } 644 645 if (!d_is_reg(dentry)) { 646 pr_err("%pd is not a file\n", dentry); 647 inode_lock_nested(d_inode(fan), I_MUTEX_PARENT); 648 ret = cachefiles_bury_object(volume->cache, object, fan, dentry, 649 FSCACHE_OBJECT_IS_WEIRD); 650 dput(dentry); 651 if (ret < 0) 652 return false; 653 goto new_file; 654 } 655 656 ret = cachefiles_open_file(object, dentry); 657 dput(dentry); 658 if (!ret) 659 return false; 660 661 _leave(" = t [%lu]", file_inode(object->file)->i_ino); 662 return true; 663 664 new_file: 665 fscache_cookie_lookup_negative(object->cookie); 666 return cachefiles_create_file(object); 667 } 668 669 /* 670 * Attempt to link a temporary file into its rightful place in the cache. 671 */ 672 bool cachefiles_commit_tmpfile(struct cachefiles_cache *cache, 673 struct cachefiles_object *object) 674 { 675 struct cachefiles_volume *volume = object->volume; 676 struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash]; 677 bool success = false; 678 int ret; 679 680 _enter(",%pD", object->file); 681 682 inode_lock_nested(d_inode(fan), I_MUTEX_PARENT); 683 ret = cachefiles_inject_read_error(); 684 if (ret == 0) 685 dentry = lookup_one(&nop_mnt_idmap, &QSTR(object->d_name), fan); 686 else 687 dentry = ERR_PTR(ret); 688 if (IS_ERR(dentry)) { 689 trace_cachefiles_vfs_error(object, d_inode(fan), PTR_ERR(dentry), 690 cachefiles_trace_lookup_error); 691 _debug("lookup fail %ld", PTR_ERR(dentry)); 692 goto out_unlock; 693 } 694 695 if (!d_is_negative(dentry)) { 696 ret = cachefiles_unlink(volume->cache, object, fan, dentry, 697 FSCACHE_OBJECT_IS_STALE); 698 if (ret < 0) 699 goto out_dput; 700 701 dput(dentry); 702 ret = cachefiles_inject_read_error(); 703 if (ret == 0) 704 dentry = lookup_one(&nop_mnt_idmap, &QSTR(object->d_name), fan); 705 else 706 dentry = ERR_PTR(ret); 707 if (IS_ERR(dentry)) { 708 trace_cachefiles_vfs_error(object, d_inode(fan), PTR_ERR(dentry), 709 cachefiles_trace_lookup_error); 710 _debug("lookup fail %ld", PTR_ERR(dentry)); 711 goto out_unlock; 712 } 713 } 714 715 ret = cachefiles_inject_read_error(); 716 if (ret == 0) 717 ret = vfs_link(object->file->f_path.dentry, &nop_mnt_idmap, 718 d_inode(fan), dentry, NULL); 719 if (ret < 0) { 720 trace_cachefiles_vfs_error(object, d_inode(fan), ret, 721 cachefiles_trace_link_error); 722 _debug("link fail %d", ret); 723 } else { 724 trace_cachefiles_link(object, file_inode(object->file)); 725 spin_lock(&object->lock); 726 /* TODO: Do we want to switch the file pointer to the new dentry? */ 727 clear_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); 728 spin_unlock(&object->lock); 729 success = true; 730 } 731 732 out_dput: 733 dput(dentry); 734 out_unlock: 735 inode_unlock(d_inode(fan)); 736 _leave(" = %u", success); 737 return success; 738 } 739 740 /* 741 * Look up an inode to be checked or culled. Return -EBUSY if the inode is 742 * marked in use. 743 */ 744 static struct dentry *cachefiles_lookup_for_cull(struct cachefiles_cache *cache, 745 struct dentry *dir, 746 char *filename) 747 { 748 struct dentry *victim; 749 int ret = -ENOENT; 750 751 inode_lock_nested(d_inode(dir), I_MUTEX_PARENT); 752 753 victim = lookup_one(&nop_mnt_idmap, &QSTR(filename), dir); 754 if (IS_ERR(victim)) 755 goto lookup_error; 756 if (d_is_negative(victim)) 757 goto lookup_put; 758 if (d_inode(victim)->i_flags & S_KERNEL_FILE) 759 goto lookup_busy; 760 return victim; 761 762 lookup_busy: 763 ret = -EBUSY; 764 lookup_put: 765 inode_unlock(d_inode(dir)); 766 dput(victim); 767 return ERR_PTR(ret); 768 769 lookup_error: 770 inode_unlock(d_inode(dir)); 771 ret = PTR_ERR(victim); 772 if (ret == -ENOENT) 773 return ERR_PTR(-ESTALE); /* Probably got retired by the netfs */ 774 775 if (ret == -EIO) { 776 cachefiles_io_error(cache, "Lookup failed"); 777 } else if (ret != -ENOMEM) { 778 pr_err("Internal error: %d\n", ret); 779 ret = -EIO; 780 } 781 782 return ERR_PTR(ret); 783 } 784 785 /* 786 * Cull an object if it's not in use 787 * - called only by cache manager daemon 788 */ 789 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir, 790 char *filename) 791 { 792 struct dentry *victim; 793 struct inode *inode; 794 int ret; 795 796 _enter(",%pd/,%s", dir, filename); 797 798 victim = cachefiles_lookup_for_cull(cache, dir, filename); 799 if (IS_ERR(victim)) 800 return PTR_ERR(victim); 801 802 /* check to see if someone is using this object */ 803 inode = d_inode(victim); 804 inode_lock(inode); 805 if (inode->i_flags & S_KERNEL_FILE) { 806 ret = -EBUSY; 807 } else { 808 /* Stop the cache from picking it back up */ 809 inode->i_flags |= S_KERNEL_FILE; 810 ret = 0; 811 } 812 inode_unlock(inode); 813 if (ret < 0) 814 goto error_unlock; 815 816 ret = cachefiles_bury_object(cache, NULL, dir, victim, 817 FSCACHE_OBJECT_WAS_CULLED); 818 if (ret < 0) 819 goto error; 820 821 fscache_count_culled(); 822 dput(victim); 823 _leave(" = 0"); 824 return 0; 825 826 error_unlock: 827 inode_unlock(d_inode(dir)); 828 error: 829 dput(victim); 830 if (ret == -ENOENT) 831 return -ESTALE; /* Probably got retired by the netfs */ 832 833 if (ret != -ENOMEM) { 834 pr_err("Internal error: %d\n", ret); 835 ret = -EIO; 836 } 837 838 _leave(" = %d", ret); 839 return ret; 840 } 841 842 /* 843 * Find out if an object is in use or not 844 * - called only by cache manager daemon 845 * - returns -EBUSY or 0 to indicate whether an object is in use or not 846 */ 847 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir, 848 char *filename) 849 { 850 struct dentry *victim; 851 int ret = 0; 852 853 victim = cachefiles_lookup_for_cull(cache, dir, filename); 854 if (IS_ERR(victim)) 855 return PTR_ERR(victim); 856 857 inode_unlock(d_inode(dir)); 858 dput(victim); 859 return ret; 860 } 861