fs/cachefiles/namei.c

   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 ([email protected])
   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(&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
 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(&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  */
 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         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  */
 416 int 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  */
 440 struct 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         }
 504 out:
 505         cachefiles_end_secure(cache, saved_cred);
 506         return file;
 507
 508 err_unuse:
 509         cachefiles_do_unmark_inode_in_use(object, file_inode(file));
 510         fput(file);
 511 err:
 512         file = ERR_PTR(ret);
 513         goto out;
 514 }
 515
 516 /*
 517  * Create a new file.
 518  */
 519 static 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  */
 544 static 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, cache->cache_cred);
 567         if (IS_ERR(file)) {
 568                 trace_cachefiles_vfs_error(object, d_backing_inode(dentry),
 569                                            PTR_ERR(file),
 570                                            cachefiles_trace_open_error);
 571                 goto error;
 572         }
 573
 574         if (unlikely(!file->f_op->read_iter) ||
 575             unlikely(!file->f_op->write_iter)) {
 576                 pr_notice("Cache does not support read_iter and write_iter\n");
 577                 goto error_fput;
 578         }
 579         _debug("file -> %pd positive", dentry);
 580
 581         ret = cachefiles_ondemand_init_object(object);
 582         if (ret < 0)
 583                 goto error_fput;
 584
 585         ret = cachefiles_check_auxdata(object, file);
 586         if (ret < 0)
 587                 goto check_failed;
 588
 589         clear_bit(FSCACHE_COOKIE_NO_DATA_TO_READ, &object->cookie->flags);
 590
 591         object->file = file;
 592
 593         /* Always update the atime on an object we've just looked up (this is
 594          * used to keep track of culling, and atimes are only updated by read,
 595          * write and readdir but not lookup or open).
 596          */
 597         touch_atime(&file->f_path);
 598         dput(dentry);
 599         return true;
 600
 601 check_failed:
 602         fscache_cookie_lookup_negative(object->cookie);
 603         cachefiles_unmark_inode_in_use(object, file);
 604         fput(file);
 605         dput(dentry);
 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         dput(dentry);
 615         return false;
 616 }
 617
 618 /*
 619  * walk from the parent object to the child object through the backing
 620  * filesystem, creating directories as we go
 621  */
 622 bool cachefiles_look_up_object(struct cachefiles_object *object)
 623 {
 624         struct cachefiles_volume *volume = object->volume;
 625         struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash];
 626         int ret;
 627
 628         _enter("OBJ%x,%s,", object->debug_id, object->d_name);
 629
 630         /* Look up path "cache/vol/fanout/file". */
 631         ret = cachefiles_inject_read_error();
 632         if (ret == 0)
 633                 dentry = lookup_positive_unlocked(object->d_name, fan,
 634                                                   object->d_name_len);
 635         else
 636                 dentry = ERR_PTR(ret);
 637         trace_cachefiles_lookup(object, fan, dentry);
 638         if (IS_ERR(dentry)) {
 639                 if (dentry == ERR_PTR(-ENOENT))
 640                         goto new_file;
 641                 if (dentry == ERR_PTR(-EIO))
 642                         cachefiles_io_error_obj(object, "Lookup failed");
 643                 return false;
 644         }
 645
 646         if (!d_is_reg(dentry)) {
 647                 pr_err("%pd is not a file\n", dentry);
 648                 inode_lock_nested(d_inode(fan), I_MUTEX_PARENT);
 649                 ret = cachefiles_bury_object(volume->cache, object, fan, dentry,
 650                                              FSCACHE_OBJECT_IS_WEIRD);
 651                 dput(dentry);
 652                 if (ret < 0)
 653                         return false;
 654                 goto new_file;
 655         }
 656
 657         if (!cachefiles_open_file(object, dentry))
 658                 return false;
 659
 660         _leave(" = t [%lu]", file_inode(object->file)->i_ino);
 661         return true;
 662
 663 new_file:
 664         fscache_cookie_lookup_negative(object->cookie);
 665         return cachefiles_create_file(object);
 666 }
 667
 668 /*
 669  * Attempt to link a temporary file into its rightful place in the cache.
 670  */
 671 bool cachefiles_commit_tmpfile(struct cachefiles_cache *cache,
 672                                struct cachefiles_object *object)
 673 {
 674         struct cachefiles_volume *volume = object->volume;
 675         struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash];
 676         bool success = false;
 677         int ret;
 678
 679         _enter(",%pD", object->file);
 680
 681         inode_lock_nested(d_inode(fan), I_MUTEX_PARENT);
 682         ret = cachefiles_inject_read_error();
 683         if (ret == 0)
 684                 dentry = lookup_one_len(object->d_name, fan, object->d_name_len);
 685         else
 686                 dentry = ERR_PTR(ret);
 687         if (IS_ERR(dentry)) {
 688                 trace_cachefiles_vfs_error(object, d_inode(fan), PTR_ERR(dentry),
 689                                            cachefiles_trace_lookup_error);
 690                 _debug("lookup fail %ld", PTR_ERR(dentry));
 691                 goto out_unlock;
 692         }
 693
 694         if (!d_is_negative(dentry)) {
 695                 if (d_backing_inode(dentry) == file_inode(object->file)) {
 696                         success = true;
 697                         goto out_dput;
 698                 }
 699
 700                 ret = cachefiles_unlink(volume->cache, object, fan, dentry,
 701                                         FSCACHE_OBJECT_IS_STALE);
 702                 if (ret < 0)
 703                         goto out_dput;
 704
 705                 dput(dentry);
 706                 ret = cachefiles_inject_read_error();
 707                 if (ret == 0)
 708                         dentry = lookup_one_len(object->d_name, fan, object->d_name_len);
 709                 else
 710                         dentry = ERR_PTR(ret);
 711                 if (IS_ERR(dentry)) {
 712                         trace_cachefiles_vfs_error(object, d_inode(fan), PTR_ERR(dentry),
 713                                                    cachefiles_trace_lookup_error);
 714                         _debug("lookup fail %ld", PTR_ERR(dentry));
 715                         goto out_unlock;
 716                 }
 717         }
 718
 719         ret = cachefiles_inject_read_error();
 720         if (ret == 0)
 721                 ret = vfs_link(object->file->f_path.dentry, &nop_mnt_idmap,
 722                                d_inode(fan), dentry, NULL);
 723         if (ret < 0) {
 724                 trace_cachefiles_vfs_error(object, d_inode(fan), ret,
 725                                            cachefiles_trace_link_error);
 726                 _debug("link fail %d", ret);
 727         } else {
 728                 trace_cachefiles_link(object, file_inode(object->file));
 729                 spin_lock(&object->lock);
 730                 /* TODO: Do we want to switch the file pointer to the new dentry? */
 731                 clear_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags);
 732                 spin_unlock(&object->lock);
 733                 success = true;
 734         }
 735
 736 out_dput:
 737         dput(dentry);
 738 out_unlock:
 739         inode_unlock(d_inode(fan));
 740         _leave(" = %u", success);
 741         return success;
 742 }
 743
 744 /*
 745  * Look up an inode to be checked or culled.  Return -EBUSY if the inode is
 746  * marked in use.
 747  */
 748 static struct dentry *cachefiles_lookup_for_cull(struct cachefiles_cache *cache,
 749                                                  struct dentry *dir,
 750                                                  char *filename)
 751 {
 752         struct dentry *victim;
 753         int ret = -ENOENT;
 754
 755         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
 756
 757         victim = lookup_one_len(filename, dir, strlen(filename));
 758         if (IS_ERR(victim))
 759                 goto lookup_error;
 760         if (d_is_negative(victim))
 761                 goto lookup_put;
 762         if (d_inode(victim)->i_flags & S_KERNEL_FILE)
 763                 goto lookup_busy;
 764         return victim;
 765
 766 lookup_busy:
 767         ret = -EBUSY;
 768 lookup_put:
 769         inode_unlock(d_inode(dir));
 770         dput(victim);
 771         return ERR_PTR(ret);
 772
 773 lookup_error:
 774         inode_unlock(d_inode(dir));
 775         ret = PTR_ERR(victim);
 776         if (ret == -ENOENT)
 777                 return ERR_PTR(-ESTALE); /* Probably got retired by the netfs */
 778
 779         if (ret == -EIO) {
 780                 cachefiles_io_error(cache, "Lookup failed");
 781         } else if (ret != -ENOMEM) {
 782                 pr_err("Internal error: %d\n", ret);
 783                 ret = -EIO;
 784         }
 785
 786         return ERR_PTR(ret);
 787 }
 788
 789 /*
 790  * Cull an object if it's not in use
 791  * - called only by cache manager daemon
 792  */
 793 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
 794                     char *filename)
 795 {
 796         struct dentry *victim;
 797         struct inode *inode;
 798         int ret;
 799
 800         _enter(",%pd/,%s", dir, filename);
 801
 802         victim = cachefiles_lookup_for_cull(cache, dir, filename);
 803         if (IS_ERR(victim))
 804                 return PTR_ERR(victim);
 805
 806         /* check to see if someone is using this object */
 807         inode = d_inode(victim);
 808         inode_lock(inode);
 809         if (inode->i_flags & S_KERNEL_FILE) {
 810                 ret = -EBUSY;
 811         } else {
 812                 /* Stop the cache from picking it back up */
 813                 inode->i_flags |= S_KERNEL_FILE;
 814                 ret = 0;
 815         }
 816         inode_unlock(inode);
 817         if (ret < 0)
 818                 goto error_unlock;
 819
 820         ret = cachefiles_bury_object(cache, NULL, dir, victim,
 821                                      FSCACHE_OBJECT_WAS_CULLED);
 822         if (ret < 0)
 823                 goto error;
 824
 825         fscache_count_culled();
 826         dput(victim);
 827         _leave(" = 0");
 828         return 0;
 829
 830 error_unlock:
 831         inode_unlock(d_inode(dir));
 832 error:
 833         dput(victim);
 834         if (ret == -ENOENT)
 835                 return -ESTALE; /* Probably got retired by the netfs */
 836
 837         if (ret != -ENOMEM) {
 838                 pr_err("Internal error: %d\n", ret);
 839                 ret = -EIO;
 840         }
 841
 842         _leave(" = %d", ret);
 843         return ret;
 844 }
 845
 846 /*
 847  * Find out if an object is in use or not
 848  * - called only by cache manager daemon
 849  * - returns -EBUSY or 0 to indicate whether an object is in use or not
 850  */
 851 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
 852                             char *filename)
 853 {
 854         struct dentry *victim;
 855         int ret = 0;
 856
 857         victim = cachefiles_lookup_for_cull(cache, dir, filename);
 858         if (IS_ERR(victim))
 859                 return PTR_ERR(victim);
 860
 861         inode_unlock(d_inode(dir));
 862         dput(victim);
 863         return ret;
 864 }