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 if (IS_ERR(trap)) 309 return PTR_ERR(trap); 310 311 /* do some checks before getting the grave dentry */ 312 if (rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) { 313 /* the entry was probably culled when we dropped the parent dir 314 * lock */ 315 unlock_rename(cache->graveyard, dir); 316 _leave(" = 0 [culled?]"); 317 return 0; 318 } 319 320 if (!d_can_lookup(cache->graveyard)) { 321 unlock_rename(cache->graveyard, dir); 322 cachefiles_io_error(cache, "Graveyard no longer a directory"); 323 return -EIO; 324 } 325 326 if (trap == rep) { 327 unlock_rename(cache->graveyard, dir); 328 cachefiles_io_error(cache, "May not make directory loop"); 329 return -EIO; 330 } 331 332 if (d_mountpoint(rep)) { 333 unlock_rename(cache->graveyard, dir); 334 cachefiles_io_error(cache, "Mountpoint in cache"); 335 return -EIO; 336 } 337 338 grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer)); 339 if (IS_ERR(grave)) { 340 unlock_rename(cache->graveyard, dir); 341 trace_cachefiles_vfs_error(object, d_inode(cache->graveyard), 342 PTR_ERR(grave), 343 cachefiles_trace_lookup_error); 344 345 if (PTR_ERR(grave) == -ENOMEM) { 346 _leave(" = -ENOMEM"); 347 return -ENOMEM; 348 } 349 350 cachefiles_io_error(cache, "Lookup error %ld", PTR_ERR(grave)); 351 return -EIO; 352 } 353 354 if (d_is_positive(grave)) { 355 unlock_rename(cache->graveyard, dir); 356 dput(grave); 357 grave = NULL; 358 cond_resched(); 359 goto try_again; 360 } 361 362 if (d_mountpoint(grave)) { 363 unlock_rename(cache->graveyard, dir); 364 dput(grave); 365 cachefiles_io_error(cache, "Mountpoint in graveyard"); 366 return -EIO; 367 } 368 369 /* target should not be an ancestor of source */ 370 if (trap == grave) { 371 unlock_rename(cache->graveyard, dir); 372 dput(grave); 373 cachefiles_io_error(cache, "May not make directory loop"); 374 return -EIO; 375 } 376 377 /* attempt the rename */ 378 path.mnt = cache->mnt; 379 path.dentry = dir; 380 path_to_graveyard.mnt = cache->mnt; 381 path_to_graveyard.dentry = cache->graveyard; 382 ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0); 383 if (ret < 0) { 384 cachefiles_io_error(cache, "Rename security error %d", ret); 385 } else { 386 struct renamedata rd = { 387 .old_mnt_idmap = &nop_mnt_idmap, 388 .old_dir = d_inode(dir), 389 .old_dentry = rep, 390 .new_mnt_idmap = &nop_mnt_idmap, 391 .new_dir = d_inode(cache->graveyard), 392 .new_dentry = grave, 393 }; 394 trace_cachefiles_rename(object, d_inode(rep)->i_ino, why); 395 ret = cachefiles_inject_read_error(); 396 if (ret == 0) 397 ret = vfs_rename(&rd); 398 if (ret != 0) 399 trace_cachefiles_vfs_error(object, d_inode(dir), ret, 400 cachefiles_trace_rename_error); 401 if (ret != 0 && ret != -ENOMEM) 402 cachefiles_io_error(cache, 403 "Rename failed with error %d", ret); 404 } 405 406 __cachefiles_unmark_inode_in_use(object, d_inode(rep)); 407 unlock_rename(cache->graveyard, dir); 408 dput(grave); 409 _leave(" = 0"); 410 return 0; 411} 412 413/* 414 * Delete a cache file. 415 */ 416int cachefiles_delete_object(struct cachefiles_object *object, 417 enum fscache_why_object_killed why) 418{ 419 struct cachefiles_volume *volume = object->volume; 420 struct dentry *dentry = object->file->f_path.dentry; 421 struct dentry *fan = volume->fanout[(u8)object->cookie->key_hash]; 422 int ret; 423 424 _enter(",OBJ%x{%pD}", object->debug_id, object->file); 425 426 /* Stop the dentry being negated if it's only pinned by a file struct. */ 427 dget(dentry); 428 429 inode_lock_nested(d_backing_inode(fan), I_MUTEX_PARENT); 430 ret = cachefiles_unlink(volume->cache, object, fan, dentry, why); 431 inode_unlock(d_backing_inode(fan)); 432 dput(dentry); 433 return ret; 434} 435 436/* 437 * Create a temporary file and leave it unattached and un-xattr'd until the 438 * time comes to discard the object from memory. 439 */ 440struct file *cachefiles_create_tmpfile(struct cachefiles_object *object) 441{ 442 struct cachefiles_volume *volume = object->volume; 443 struct cachefiles_cache *cache = volume->cache; 444 const struct cred *saved_cred; 445 struct dentry *fan = volume->fanout[(u8)object->cookie->key_hash]; 446 struct file *file; 447 const struct path parentpath = { .mnt = cache->mnt, .dentry = fan }; 448 uint64_t ni_size; 449 long ret; 450 451 452 cachefiles_begin_secure(cache, &saved_cred); 453 454 ret = cachefiles_inject_write_error(); 455 if (ret == 0) { 456 file = kernel_tmpfile_open(&nop_mnt_idmap, &parentpath, 457 S_IFREG | 0600, 458 O_RDWR | O_LARGEFILE | O_DIRECT, 459 cache->cache_cred); 460 ret = PTR_ERR_OR_ZERO(file); 461 } 462 if (ret) { 463 trace_cachefiles_vfs_error(object, d_inode(fan), ret, 464 cachefiles_trace_tmpfile_error); 465 if (ret == -EIO) 466 cachefiles_io_error_obj(object, "Failed to create tmpfile"); 467 goto err; 468 } 469 470 trace_cachefiles_tmpfile(object, file_inode(file)); 471 472 /* This is a newly created file with no other possible user */ 473 if (!cachefiles_mark_inode_in_use(object, file_inode(file))) 474 WARN_ON(1); 475 476 ret = cachefiles_ondemand_init_object(object); 477 if (ret < 0) 478 goto err_unuse; 479 480 ni_size = object->cookie->object_size; 481 ni_size = round_up(ni_size, CACHEFILES_DIO_BLOCK_SIZE); 482 483 if (ni_size > 0) { 484 trace_cachefiles_trunc(object, file_inode(file), 0, ni_size, 485 cachefiles_trunc_expand_tmpfile); 486 ret = cachefiles_inject_write_error(); 487 if (ret == 0) 488 ret = vfs_truncate(&file->f_path, ni_size); 489 if (ret < 0) { 490 trace_cachefiles_vfs_error( 491 object, file_inode(file), ret, 492 cachefiles_trace_trunc_error); 493 goto err_unuse; 494 } 495 } 496 497 ret = -EINVAL; 498 if (unlikely(!file->f_op->read_iter) || 499 unlikely(!file->f_op->write_iter)) { 500 fput(file); 501 pr_notice("Cache does not support read_iter and write_iter\n"); 502 goto err_unuse; 503 } 504out: 505 cachefiles_end_secure(cache, saved_cred); 506 return file; 507 508err_unuse: 509 cachefiles_do_unmark_inode_in_use(object, file_inode(file)); 510 fput(file); 511err: 512 file = ERR_PTR(ret); 513 goto out; 514} 515 516/* 517 * Create a new file. 518 */ 519static bool cachefiles_create_file(struct cachefiles_object *object) 520{ 521 struct file *file; 522 int ret; 523 524 ret = cachefiles_has_space(object->volume->cache, 1, 0, 525 cachefiles_has_space_for_create); 526 if (ret < 0) 527 return false; 528 529 file = cachefiles_create_tmpfile(object); 530 if (IS_ERR(file)) 531 return false; 532 533 set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags); 534 set_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); 535 _debug("create -> %pD{ino=%lu}", file, file_inode(file)->i_ino); 536 object->file = file; 537 return true; 538} 539 540/* 541 * Open an existing file, checking its attributes and replacing it if it is 542 * stale. 543 */ 544static bool cachefiles_open_file(struct cachefiles_object *object, 545 struct dentry *dentry) 546{ 547 struct cachefiles_cache *cache = object->volume->cache; 548 struct file *file; 549 struct path path; 550 int ret; 551 552 _enter("%pd", dentry); 553 554 if (!cachefiles_mark_inode_in_use(object, d_inode(dentry))) { 555 pr_notice("cachefiles: Inode already in use: %pd (B=%lx)\n", 556 dentry, d_inode(dentry)->i_ino); 557 return false; 558 } 559 560 /* We need to open a file interface onto a data file now as we can't do 561 * it on demand because writeback called from do_exit() sees 562 * current->fs == NULL - which breaks d_path() called from ext4 open. 563 */ 564 path.mnt = cache->mnt; 565 path.dentry = dentry; 566 file = kernel_file_open(&path, O_RDWR | O_LARGEFILE | O_DIRECT, 567 d_backing_inode(dentry), cache->cache_cred); 568 if (IS_ERR(file)) { 569 trace_cachefiles_vfs_error(object, d_backing_inode(dentry), 570 PTR_ERR(file), 571 cachefiles_trace_open_error); 572 goto error; 573 } 574 575 if (unlikely(!file->f_op->read_iter) || 576 unlikely(!file->f_op->write_iter)) { 577 pr_notice("Cache does not support read_iter and write_iter\n"); 578 goto error_fput; 579 } 580 _debug("file -> %pd positive", dentry); 581 582 ret = cachefiles_ondemand_init_object(object); 583 if (ret < 0) 584 goto error_fput; 585 586 ret = cachefiles_check_auxdata(object, file); 587 if (ret < 0) 588 goto check_failed; 589 590 clear_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &object->cookie->flags); 591 592 object->file = file; 593 594 /* Always update the atime on an object we've just looked up (this is 595 * used to keep track of culling, and atimes are only updated by read, 596 * write and readdir but not lookup or open). 597 */ 598 touch_atime(&file->f_path); 599 dput(dentry); 600 return true; 601 602check_failed: 603 fscache_cookie_lookup_negative(object->cookie); 604 cachefiles_unmark_inode_in_use(object, file); 605 fput(file); 606 dput(dentry); 607 if (ret == -ESTALE) 608 return cachefiles_create_file(object); 609 return false; 610 611error_fput: 612 fput(file); 613error: 614 cachefiles_do_unmark_inode_in_use(object, d_inode(dentry)); 615 dput(dentry); 616 return false; 617} 618 619/* 620 * walk from the parent object to the child object through the backing 621 * filesystem, creating directories as we go 622 */ 623bool cachefiles_look_up_object(struct cachefiles_object *object) 624{ 625 struct cachefiles_volume *volume = object->volume; 626 struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash]; 627 int ret; 628 629 _enter("OBJ%x,%s,", object->debug_id, object->d_name); 630 631 /* Look up path "cache/vol/fanout/file". */ 632 ret = cachefiles_inject_read_error(); 633 if (ret == 0) 634 dentry = lookup_positive_unlocked(object->d_name, fan, 635 object->d_name_len); 636 else 637 dentry = ERR_PTR(ret); 638 trace_cachefiles_lookup(object, fan, dentry); 639 if (IS_ERR(dentry)) { 640 if (dentry == ERR_PTR(-ENOENT)) 641 goto new_file; 642 if (dentry == ERR_PTR(-EIO)) 643 cachefiles_io_error_obj(object, "Lookup failed"); 644 return false; 645 } 646 647 if (!d_is_reg(dentry)) { 648 pr_err("%pd is not a file\n", dentry); 649 inode_lock_nested(d_inode(fan), I_MUTEX_PARENT); 650 ret = cachefiles_bury_object(volume->cache, object, fan, dentry, 651 FSCACHE_OBJECT_IS_WEIRD); 652 dput(dentry); 653 if (ret < 0) 654 return false; 655 goto new_file; 656 } 657 658 if (!cachefiles_open_file(object, dentry)) 659 return false; 660 661 _leave(" = t [%lu]", file_inode(object->file)->i_ino); 662 return true; 663 664new_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 */ 672bool 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_len(object->d_name, fan, object->d_name_len); 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 if (d_backing_inode(dentry) == file_inode(object->file)) { 697 success = true; 698 goto out_dput; 699 } 700 701 ret = cachefiles_unlink(volume->cache, object, fan, dentry, 702 FSCACHE_OBJECT_IS_STALE); 703 if (ret < 0) 704 goto out_dput; 705 706 dput(dentry); 707 ret = cachefiles_inject_read_error(); 708 if (ret == 0) 709 dentry = lookup_one_len(object->d_name, fan, object->d_name_len); 710 else 711 dentry = ERR_PTR(ret); 712 if (IS_ERR(dentry)) { 713 trace_cachefiles_vfs_error(object, d_inode(fan), PTR_ERR(dentry), 714 cachefiles_trace_lookup_error); 715 _debug("lookup fail %ld", PTR_ERR(dentry)); 716 goto out_unlock; 717 } 718 } 719 720 ret = cachefiles_inject_read_error(); 721 if (ret == 0) 722 ret = vfs_link(object->file->f_path.dentry, &nop_mnt_idmap, 723 d_inode(fan), dentry, NULL); 724 if (ret < 0) { 725 trace_cachefiles_vfs_error(object, d_inode(fan), ret, 726 cachefiles_trace_link_error); 727 _debug("link fail %d", ret); 728 } else { 729 trace_cachefiles_link(object, file_inode(object->file)); 730 spin_lock(&object->lock); 731 /* TODO: Do we want to switch the file pointer to the new dentry? */ 732 clear_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); 733 spin_unlock(&object->lock); 734 success = true; 735 } 736 737out_dput: 738 dput(dentry); 739out_unlock: 740 inode_unlock(d_inode(fan)); 741 _leave(" = %u", success); 742 return success; 743} 744 745/* 746 * Look up an inode to be checked or culled. Return -EBUSY if the inode is 747 * marked in use. 748 */ 749static struct dentry *cachefiles_lookup_for_cull(struct cachefiles_cache *cache, 750 struct dentry *dir, 751 char *filename) 752{ 753 struct dentry *victim; 754 int ret = -ENOENT; 755 756 inode_lock_nested(d_inode(dir), I_MUTEX_PARENT); 757 758 victim = lookup_one_len(filename, dir, strlen(filename)); 759 if (IS_ERR(victim)) 760 goto lookup_error; 761 if (d_is_negative(victim)) 762 goto lookup_put; 763 if (d_inode(victim)->i_flags & S_KERNEL_FILE) 764 goto lookup_busy; 765 return victim; 766 767lookup_busy: 768 ret = -EBUSY; 769lookup_put: 770 inode_unlock(d_inode(dir)); 771 dput(victim); 772 return ERR_PTR(ret); 773 774lookup_error: 775 inode_unlock(d_inode(dir)); 776 ret = PTR_ERR(victim); 777 if (ret == -ENOENT) 778 return ERR_PTR(-ESTALE); /* Probably got retired by the netfs */ 779 780 if (ret == -EIO) { 781 cachefiles_io_error(cache, "Lookup failed"); 782 } else if (ret != -ENOMEM) { 783 pr_err("Internal error: %d\n", ret); 784 ret = -EIO; 785 } 786 787 return ERR_PTR(ret); 788} 789 790/* 791 * Cull an object if it's not in use 792 * - called only by cache manager daemon 793 */ 794int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir, 795 char *filename) 796{ 797 struct dentry *victim; 798 struct inode *inode; 799 int ret; 800 801 _enter(",%pd/,%s", dir, filename); 802 803 victim = cachefiles_lookup_for_cull(cache, dir, filename); 804 if (IS_ERR(victim)) 805 return PTR_ERR(victim); 806 807 /* check to see if someone is using this object */ 808 inode = d_inode(victim); 809 inode_lock(inode); 810 if (inode->i_flags & S_KERNEL_FILE) { 811 ret = -EBUSY; 812 } else { 813 /* Stop the cache from picking it back up */ 814 inode->i_flags |= S_KERNEL_FILE; 815 ret = 0; 816 } 817 inode_unlock(inode); 818 if (ret < 0) 819 goto error_unlock; 820 821 ret = cachefiles_bury_object(cache, NULL, dir, victim, 822 FSCACHE_OBJECT_WAS_CULLED); 823 if (ret < 0) 824 goto error; 825 826 fscache_count_culled(); 827 dput(victim); 828 _leave(" = 0"); 829 return 0; 830 831error_unlock: 832 inode_unlock(d_inode(dir)); 833error: 834 dput(victim); 835 if (ret == -ENOENT) 836 return -ESTALE; /* Probably got retired by the netfs */ 837 838 if (ret != -ENOMEM) { 839 pr_err("Internal error: %d\n", ret); 840 ret = -EIO; 841 } 842 843 _leave(" = %d", ret); 844 return ret; 845} 846 847/* 848 * Find out if an object is in use or not 849 * - called only by cache manager daemon 850 * - returns -EBUSY or 0 to indicate whether an object is in use or not 851 */ 852int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir, 853 char *filename) 854{ 855 struct dentry *victim; 856 int ret = 0; 857 858 victim = cachefiles_lookup_for_cull(cache, dir, filename); 859 if (IS_ERR(victim)) 860 return PTR_ERR(victim); 861 862 inode_unlock(d_inode(dir)); 863 dput(victim); 864 return ret; 865} 866