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 */ 17static 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 33static 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 */ 47static 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 54static 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 */ 66void 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 */ 84struct 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 98retry: 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(&nop_mnt_idmap, 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 186check_error: 187 cachefiles_put_directory(subdir); 188 _leave(" = %d [check]", ret); 189 return ERR_PTR(ret); 190 191mark_error: 192 inode_unlock(d_inode(subdir)); 193 dput(subdir); 194 return ERR_PTR(-EBUSY); 195 196mkdir_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 202lookup_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 208nomem_d_alloc: 209 inode_unlock(d_inode(dir)); 210 _leave(" = -ENOMEM"); 211 return ERR_PTR(-ENOMEM); 212} 213 214/* 215 * Put a subdirectory. 216 */ 217void 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 */ 228static 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(&nop_mnt_idmap, 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 */ 264int 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 300try_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_idmap = &nop_mnt_idmap, 386 .old_dir = d_inode(dir), 387 .old_dentry = rep, 388 .new_mnt_idmap = &nop_mnt_idmap, 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 */ 414int 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 */ 438struct 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 const struct path parentpath = { .mnt = cache->mnt, .dentry = fan }; 446 uint64_t ni_size; 447 long ret; 448 449 450 cachefiles_begin_secure(cache, &saved_cred); 451 452 ret = cachefiles_inject_write_error(); 453 if (ret == 0) { 454 file = kernel_tmpfile_open(&nop_mnt_idmap, &parentpath, 455 S_IFREG | 0600, 456 O_RDWR | O_LARGEFILE | O_DIRECT, 457 cache->cache_cred); 458 ret = PTR_ERR_OR_ZERO(file); 459 } 460 if (ret) { 461 trace_cachefiles_vfs_error(object, d_inode(fan), ret, 462 cachefiles_trace_tmpfile_error); 463 if (ret == -EIO) 464 cachefiles_io_error_obj(object, "Failed to create tmpfile"); 465 goto err; 466 } 467 468 trace_cachefiles_tmpfile(object, file_inode(file)); 469 470 /* This is a newly created file with no other possible user */ 471 if (!cachefiles_mark_inode_in_use(object, file_inode(file))) 472 WARN_ON(1); 473 474 ret = cachefiles_ondemand_init_object(object); 475 if (ret < 0) 476 goto err_unuse; 477 478 ni_size = object->cookie->object_size; 479 ni_size = round_up(ni_size, CACHEFILES_DIO_BLOCK_SIZE); 480 481 if (ni_size > 0) { 482 trace_cachefiles_trunc(object, file_inode(file), 0, ni_size, 483 cachefiles_trunc_expand_tmpfile); 484 ret = cachefiles_inject_write_error(); 485 if (ret == 0) 486 ret = vfs_truncate(&file->f_path, ni_size); 487 if (ret < 0) { 488 trace_cachefiles_vfs_error( 489 object, file_inode(file), ret, 490 cachefiles_trace_trunc_error); 491 goto err_unuse; 492 } 493 } 494 495 ret = -EINVAL; 496 if (unlikely(!file->f_op->read_iter) || 497 unlikely(!file->f_op->write_iter)) { 498 fput(file); 499 pr_notice("Cache does not support read_iter and write_iter\n"); 500 goto err_unuse; 501 } 502out: 503 cachefiles_end_secure(cache, saved_cred); 504 return file; 505 506err_unuse: 507 cachefiles_do_unmark_inode_in_use(object, file_inode(file)); 508 fput(file); 509err: 510 file = ERR_PTR(ret); 511 goto out; 512} 513 514/* 515 * Create a new file. 516 */ 517static bool cachefiles_create_file(struct cachefiles_object *object) 518{ 519 struct file *file; 520 int ret; 521 522 ret = cachefiles_has_space(object->volume->cache, 1, 0, 523 cachefiles_has_space_for_create); 524 if (ret < 0) 525 return false; 526 527 file = cachefiles_create_tmpfile(object); 528 if (IS_ERR(file)) 529 return false; 530 531 set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags); 532 set_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); 533 _debug("create -> %pD{ino=%lu}", file, file_inode(file)->i_ino); 534 object->file = file; 535 return true; 536} 537 538/* 539 * Open an existing file, checking its attributes and replacing it if it is 540 * stale. 541 */ 542static bool cachefiles_open_file(struct cachefiles_object *object, 543 struct dentry *dentry) 544{ 545 struct cachefiles_cache *cache = object->volume->cache; 546 struct file *file; 547 struct path path; 548 int ret; 549 550 _enter("%pd", dentry); 551 552 if (!cachefiles_mark_inode_in_use(object, d_inode(dentry))) { 553 pr_notice("cachefiles: Inode already in use: %pd (B=%lx)\n", 554 dentry, d_inode(dentry)->i_ino); 555 return false; 556 } 557 558 /* We need to open a file interface onto a data file now as we can't do 559 * it on demand because writeback called from do_exit() sees 560 * current->fs == NULL - which breaks d_path() called from ext4 open. 561 */ 562 path.mnt = cache->mnt; 563 path.dentry = dentry; 564 file = kernel_file_open(&path, O_RDWR | O_LARGEFILE | O_DIRECT, 565 d_backing_inode(dentry), cache->cache_cred); 566 if (IS_ERR(file)) { 567 trace_cachefiles_vfs_error(object, d_backing_inode(dentry), 568 PTR_ERR(file), 569 cachefiles_trace_open_error); 570 goto error; 571 } 572 573 if (unlikely(!file->f_op->read_iter) || 574 unlikely(!file->f_op->write_iter)) { 575 pr_notice("Cache does not support read_iter and write_iter\n"); 576 goto error_fput; 577 } 578 _debug("file -> %pd positive", dentry); 579 580 ret = cachefiles_ondemand_init_object(object); 581 if (ret < 0) 582 goto error_fput; 583 584 ret = cachefiles_check_auxdata(object, file); 585 if (ret < 0) 586 goto check_failed; 587 588 clear_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &object->cookie->flags); 589 590 object->file = file; 591 592 /* Always update the atime on an object we've just looked up (this is 593 * used to keep track of culling, and atimes are only updated by read, 594 * write and readdir but not lookup or open). 595 */ 596 touch_atime(&file->f_path); 597 dput(dentry); 598 return true; 599 600check_failed: 601 fscache_cookie_lookup_negative(object->cookie); 602 cachefiles_unmark_inode_in_use(object, file); 603 fput(file); 604 dput(dentry); 605 if (ret == -ESTALE) 606 return cachefiles_create_file(object); 607 return false; 608 609error_fput: 610 fput(file); 611error: 612 cachefiles_do_unmark_inode_in_use(object, d_inode(dentry)); 613 dput(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 */ 621bool 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_positive_unlocked(object->d_name, fan, 633 object->d_name_len); 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 if (!cachefiles_open_file(object, dentry)) 657 return false; 658 659 _leave(" = t [%lu]", file_inode(object->file)->i_ino); 660 return true; 661 662new_file: 663 fscache_cookie_lookup_negative(object->cookie); 664 return cachefiles_create_file(object); 665} 666 667/* 668 * Attempt to link a temporary file into its rightful place in the cache. 669 */ 670bool cachefiles_commit_tmpfile(struct cachefiles_cache *cache, 671 struct cachefiles_object *object) 672{ 673 struct cachefiles_volume *volume = object->volume; 674 struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash]; 675 bool success = false; 676 int ret; 677 678 _enter(",%pD", object->file); 679 680 inode_lock_nested(d_inode(fan), I_MUTEX_PARENT); 681 ret = cachefiles_inject_read_error(); 682 if (ret == 0) 683 dentry = lookup_one_len(object->d_name, fan, object->d_name_len); 684 else 685 dentry = ERR_PTR(ret); 686 if (IS_ERR(dentry)) { 687 trace_cachefiles_vfs_error(object, d_inode(fan), PTR_ERR(dentry), 688 cachefiles_trace_lookup_error); 689 _debug("lookup fail %ld", PTR_ERR(dentry)); 690 goto out_unlock; 691 } 692 693 if (!d_is_negative(dentry)) { 694 if (d_backing_inode(dentry) == file_inode(object->file)) { 695 success = true; 696 goto out_dput; 697 } 698 699 ret = cachefiles_unlink(volume->cache, object, fan, dentry, 700 FSCACHE_OBJECT_IS_STALE); 701 if (ret < 0) 702 goto out_dput; 703 704 dput(dentry); 705 ret = cachefiles_inject_read_error(); 706 if (ret == 0) 707 dentry = lookup_one_len(object->d_name, fan, object->d_name_len); 708 else 709 dentry = ERR_PTR(ret); 710 if (IS_ERR(dentry)) { 711 trace_cachefiles_vfs_error(object, d_inode(fan), PTR_ERR(dentry), 712 cachefiles_trace_lookup_error); 713 _debug("lookup fail %ld", PTR_ERR(dentry)); 714 goto out_unlock; 715 } 716 } 717 718 ret = cachefiles_inject_read_error(); 719 if (ret == 0) 720 ret = vfs_link(object->file->f_path.dentry, &nop_mnt_idmap, 721 d_inode(fan), dentry, NULL); 722 if (ret < 0) { 723 trace_cachefiles_vfs_error(object, d_inode(fan), ret, 724 cachefiles_trace_link_error); 725 _debug("link fail %d", ret); 726 } else { 727 trace_cachefiles_link(object, file_inode(object->file)); 728 spin_lock(&object->lock); 729 /* TODO: Do we want to switch the file pointer to the new dentry? */ 730 clear_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); 731 spin_unlock(&object->lock); 732 success = true; 733 } 734 735out_dput: 736 dput(dentry); 737out_unlock: 738 inode_unlock(d_inode(fan)); 739 _leave(" = %u", success); 740 return success; 741} 742 743/* 744 * Look up an inode to be checked or culled. Return -EBUSY if the inode is 745 * marked in use. 746 */ 747static struct dentry *cachefiles_lookup_for_cull(struct cachefiles_cache *cache, 748 struct dentry *dir, 749 char *filename) 750{ 751 struct dentry *victim; 752 int ret = -ENOENT; 753 754 inode_lock_nested(d_inode(dir), I_MUTEX_PARENT); 755 756 victim = lookup_one_len(filename, dir, strlen(filename)); 757 if (IS_ERR(victim)) 758 goto lookup_error; 759 if (d_is_negative(victim)) 760 goto lookup_put; 761 if (d_inode(victim)->i_flags & S_KERNEL_FILE) 762 goto lookup_busy; 763 return victim; 764 765lookup_busy: 766 ret = -EBUSY; 767lookup_put: 768 inode_unlock(d_inode(dir)); 769 dput(victim); 770 return ERR_PTR(ret); 771 772lookup_error: 773 inode_unlock(d_inode(dir)); 774 ret = PTR_ERR(victim); 775 if (ret == -ENOENT) 776 return ERR_PTR(-ESTALE); /* Probably got retired by the netfs */ 777 778 if (ret == -EIO) { 779 cachefiles_io_error(cache, "Lookup failed"); 780 } else if (ret != -ENOMEM) { 781 pr_err("Internal error: %d\n", ret); 782 ret = -EIO; 783 } 784 785 return ERR_PTR(ret); 786} 787 788/* 789 * Cull an object if it's not in use 790 * - called only by cache manager daemon 791 */ 792int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir, 793 char *filename) 794{ 795 struct dentry *victim; 796 struct inode *inode; 797 int ret; 798 799 _enter(",%pd/,%s", dir, filename); 800 801 victim = cachefiles_lookup_for_cull(cache, dir, filename); 802 if (IS_ERR(victim)) 803 return PTR_ERR(victim); 804 805 /* check to see if someone is using this object */ 806 inode = d_inode(victim); 807 inode_lock(inode); 808 if (inode->i_flags & S_KERNEL_FILE) { 809 ret = -EBUSY; 810 } else { 811 /* Stop the cache from picking it back up */ 812 inode->i_flags |= S_KERNEL_FILE; 813 ret = 0; 814 } 815 inode_unlock(inode); 816 if (ret < 0) 817 goto error_unlock; 818 819 ret = cachefiles_bury_object(cache, NULL, dir, victim, 820 FSCACHE_OBJECT_WAS_CULLED); 821 if (ret < 0) 822 goto error; 823 824 fscache_count_culled(); 825 dput(victim); 826 _leave(" = 0"); 827 return 0; 828 829error_unlock: 830 inode_unlock(d_inode(dir)); 831error: 832 dput(victim); 833 if (ret == -ENOENT) 834 return -ESTALE; /* Probably got retired by the netfs */ 835 836 if (ret != -ENOMEM) { 837 pr_err("Internal error: %d\n", ret); 838 ret = -EIO; 839 } 840 841 _leave(" = %d", ret); 842 return ret; 843} 844 845/* 846 * Find out if an object is in use or not 847 * - called only by cache manager daemon 848 * - returns -EBUSY or 0 to indicate whether an object is in use or not 849 */ 850int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir, 851 char *filename) 852{ 853 struct dentry *victim; 854 int ret = 0; 855 856 victim = cachefiles_lookup_for_cull(cache, dir, filename); 857 if (IS_ERR(victim)) 858 return PTR_ERR(victim); 859 860 inode_unlock(d_inode(dir)); 861 dput(victim); 862 return ret; 863} 864