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 (dhowells@redhat.com)
   6  */
   7
   8 #include <linux/fs.h>
   9 #include <linux/namei.h>
  10 #include "internal.h"
  11
  12 /*
  13  * Mark the backing file as being a cache file if it's not already in use.  The
  14  * mark tells the culling request command that it's not allowed to cull the
  15  * file or directory.  The caller must hold the inode lock.
  16  */
  17 static bool __cachefiles_mark_inode_in_use(struct cachefiles_object *object,
  18                                            struct inode *inode)
  19 {
  20         bool can_use = false;
  21
  22         if (!(inode->i_flags & S_KERNEL_FILE)) {
  23                 inode->i_flags |= S_KERNEL_FILE;
  24                 trace_cachefiles_mark_active(object, inode);
  25                 can_use = true;
  26         } else {
  27                 trace_cachefiles_mark_failed(object, inode);
  28         }
  29
  30         return can_use;
  31 }
  32
  33 static bool cachefiles_mark_inode_in_use(struct cachefiles_object *object,
  34                                          struct inode *inode)
  35 {
  36         bool can_use;
  37
  38         inode_lock(inode);
  39         can_use = __cachefiles_mark_inode_in_use(object, inode);
  40         inode_unlock(inode);
  41         return can_use;
  42 }
  43
  44 /*
  45  * Unmark a backing inode.  The caller must hold the inode lock.
  46  */
  47 static void __cachefiles_unmark_inode_in_use(struct cachefiles_object *object,
  48                                              struct inode *inode)
  49 {
  50         inode->i_flags &= ~S_KERNEL_FILE;
  51         trace_cachefiles_mark_inactive(object, inode);
  52 }
  53
  54 static void cachefiles_do_unmark_inode_in_use(struct cachefiles_object *object,
  55                                               struct inode *inode)
  56 {
  57         inode_lock(inode);
  58         __cachefiles_unmark_inode_in_use(object, inode);
  59         inode_unlock(inode);
  60 }
  61
  62 /*
  63  * Unmark a backing inode and tell cachefilesd that there's something that can
  64  * be culled.
  65  */
  66 void cachefiles_unmark_inode_in_use(struct cachefiles_object *object,
  67                                     struct file *file)
  68 {
  69         struct cachefiles_cache *cache = object->volume->cache;
  70         struct inode *inode = file_inode(file);
  71
  72         cachefiles_do_unmark_inode_in_use(object, inode);
  73
  74         if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) {
  75                 atomic_long_add(inode->i_blocks, &cache->b_released);
  76                 if (atomic_inc_return(&cache->f_released))
  77                         cachefiles_state_changed(cache);
  78         }
  79 }
  80
  81 /*
  82  * get a subdirectory
  83  */
  84 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
  85                                         struct dentry *dir,
  86                                         const char *dirname,
  87                                         bool *_is_new)
  88 {
  89         struct dentry *subdir;
  90         struct path path;
  91         int ret;
  92
  93         _enter(",,%s", dirname);
  94
  95         /* search the current directory for the element name */
  96         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
  97
  98 retry:
  99         ret = cachefiles_inject_read_error();
 100         if (ret == 0)
 101                 subdir = lookup_one_len(dirname, dir, strlen(dirname));
 102         else
 103                 subdir = ERR_PTR(ret);
 104         trace_cachefiles_lookup(NULL, dir, subdir);
 105         if (IS_ERR(subdir)) {
 106                 trace_cachefiles_vfs_error(NULL, d_backing_inode(dir),
 107                                            PTR_ERR(subdir),
 108                                            cachefiles_trace_lookup_error);
 109                 if (PTR_ERR(subdir) == -ENOMEM)
 110                         goto nomem_d_alloc;
 111                 goto lookup_error;
 112         }
 113
 114         _debug("subdir -> %pd %s",
 115                subdir, d_backing_inode(subdir) ? "positive" : "negative");
 116
 117         /* we need to create the subdir if it doesn't exist yet */
 118         if (d_is_negative(subdir)) {
 119                 ret = cachefiles_has_space(cache, 1, 0,
 120                                            cachefiles_has_space_for_create);
 121                 if (ret < 0)
 122                         goto mkdir_error;
 123
 124                 _debug("attempt mkdir");
 125
 126                 path.mnt = cache->mnt;
 127                 path.dentry = dir;
 128                 ret = security_path_mkdir(&path, subdir, 0700);
 129                 if (ret < 0)
 130                         goto mkdir_error;
 131                 ret = cachefiles_inject_write_error();
 132                 if (ret == 0)
 133                         ret = vfs_mkdir(&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
 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  */
 414 int cachefiles_delete_object(struct cachefiles_object *object,
 415                              enum fscache_why_object_killed why)
 416 {
 417         struct cachefiles_volume *volume = object->volume;
 418         struct dentry *dentry = object->file->f_path.dentry;
 419         struct dentry *fan = volume->fanout[(u8)object->cookie->key_hash];
 420         int ret;
 421
 422         _enter(",OBJ%x{%pD}", object->debug_id, object->file);
 423
 424         /* Stop the dentry being negated if it's only pinned by a file struct. */
 425         dget(dentry);
 426
 427         inode_lock_nested(d_backing_inode(fan), I_MUTEX_PARENT);
 428         ret = cachefiles_unlink(volume->cache, object, fan, dentry, why);
 429         inode_unlock(d_backing_inode(fan));
 430         dput(dentry);
 431         return ret;
 432 }
 433
 434 /*
 435  * Create a temporary file and leave it unattached and un-xattr'd until the
 436  * time comes to discard the object from memory.
 437  */
 438 struct file *cachefiles_create_tmpfile(struct cachefiles_object *object)
 439 {
 440         struct cachefiles_volume *volume = object->volume;
 441         struct cachefiles_cache *cache = volume->cache;
 442         const struct cred *saved_cred;
 443         struct dentry *fan = volume->fanout[(u8)object->cookie->key_hash];
 444         struct file *file;
 445         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 = vfs_tmpfile_open(&nop_mnt_idmap, &parentpath, S_IFREG,
 455                                         O_RDWR | O_LARGEFILE | O_DIRECT,
 456                                         cache->cache_cred);
 457                 ret = PTR_ERR_OR_ZERO(file);
 458         }
 459         if (ret) {
 460                 trace_cachefiles_vfs_error(object, d_inode(fan), ret,
 461                                            cachefiles_trace_tmpfile_error);
 462                 if (ret == -EIO)
 463                         cachefiles_io_error_obj(object, "Failed to create tmpfile");
 464                 goto err;
 465         }
 466
 467         trace_cachefiles_tmpfile(object, file_inode(file));
 468
 469         /* This is a newly created file with no other possible user */
 470         if (!cachefiles_mark_inode_in_use(object, file_inode(file)))
 471                 WARN_ON(1);
 472
 473         ret = cachefiles_ondemand_init_object(object);
 474         if (ret < 0)
 475                 goto err_unuse;
 476
 477         ni_size = object->cookie->object_size;
 478         ni_size = round_up(ni_size, CACHEFILES_DIO_BLOCK_SIZE);
 479
 480         if (ni_size > 0) {
 481                 trace_cachefiles_trunc(object, file_inode(file), 0, ni_size,
 482                                        cachefiles_trunc_expand_tmpfile);
 483                 ret = cachefiles_inject_write_error();
 484                 if (ret == 0)
 485                         ret = vfs_truncate(&file->f_path, ni_size);
 486                 if (ret < 0) {
 487                         trace_cachefiles_vfs_error(
 488                                 object, file_inode(file), ret,
 489                                 cachefiles_trace_trunc_error);
 490                         goto err_unuse;
 491                 }
 492         }
 493
 494         ret = -EINVAL;
 495         if (unlikely(!file->f_op->read_iter) ||
 496             unlikely(!file->f_op->write_iter)) {
 497                 fput(file);
 498                 pr_notice("Cache does not support read_iter and write_iter\n");
 499                 goto err_unuse;
 500         }
 501 out:
 502         cachefiles_end_secure(cache, saved_cred);
 503         return file;
 504
 505 err_unuse:
 506         cachefiles_do_unmark_inode_in_use(object, file_inode(file));
 507         fput(file);
 508 err:
 509         file = ERR_PTR(ret);
 510         goto out;
 511 }
 512
 513 /*
 514  * Create a new file.
 515  */
 516 static bool cachefiles_create_file(struct cachefiles_object *object)
 517 {
 518         struct file *file;
 519         int ret;
 520
 521         ret = cachefiles_has_space(object->volume->cache, 1, 0,
 522                                    cachefiles_has_space_for_create);
 523         if (ret < 0)
 524                 return false;
 525
 526         file = cachefiles_create_tmpfile(object);
 527         if (IS_ERR(file))
 528                 return false;
 529
 530         set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags);
 531         set_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags);
 532         _debug("create -> %pD{ino=%lu}", file, file_inode(file)->i_ino);
 533         object->file = file;
 534         return true;
 535 }
 536
 537 /*
 538  * Open an existing file, checking its attributes and replacing it if it is
 539  * stale.
 540  */
 541 static bool cachefiles_open_file(struct cachefiles_object *object,
 542                                  struct dentry *dentry)
 543 {
 544         struct cachefiles_cache *cache = object->volume->cache;
 545         struct file *file;
 546         struct path path;
 547         int ret;
 548
 549         _enter("%pd", dentry);
 550
 551         if (!cachefiles_mark_inode_in_use(object, d_inode(dentry))) {
 552                 pr_notice("cachefiles: Inode already in use: %pd (B=%lx)\n",
 553                           dentry, d_inode(dentry)->i_ino);
 554                 return false;
 555         }
 556
 557         /* We need to open a file interface onto a data file now as we can't do
 558          * it on demand because writeback called from do_exit() sees
 559          * current->fs == NULL - which breaks d_path() called from ext4 open.
 560          */
 561         path.mnt = cache->mnt;
 562         path.dentry = dentry;
 563         file = open_with_fake_path(&path, O_RDWR | O_LARGEFILE | O_DIRECT,
 564                                    d_backing_inode(dentry), cache->cache_cred);
 565         if (IS_ERR(file)) {
 566                 trace_cachefiles_vfs_error(object, d_backing_inode(dentry),
 567                                            PTR_ERR(file),
 568                                            cachefiles_trace_open_error);
 569                 goto error;
 570         }
 571
 572         if (unlikely(!file->f_op->read_iter) ||
 573             unlikely(!file->f_op->write_iter)) {
 574                 pr_notice("Cache does not support read_iter and write_iter\n");
 575                 goto error_fput;
 576         }
 577         _debug("file -> %pd positive", dentry);
 578
 579         ret = cachefiles_ondemand_init_object(object);
 580         if (ret < 0)
 581                 goto error_fput;
 582
 583         ret = cachefiles_check_auxdata(object, file);
 584         if (ret < 0)
 585                 goto check_failed;
 586
 587         object->file = file;
 588
 589         /* Always update the atime on an object we've just looked up (this is
 590          * used to keep track of culling, and atimes are only updated by read,
 591          * write and readdir but not lookup or open).
 592          */
 593         touch_atime(&file->f_path);
 594         dput(dentry);
 595         return true;
 596
 597 check_failed:
 598         fscache_cookie_lookup_negative(object->cookie);
 599         cachefiles_unmark_inode_in_use(object, file);
 600         fput(file);
 601         dput(dentry);
 602         if (ret == -ESTALE)
 603                 return cachefiles_create_file(object);
 604         return false;
 605
 606 error_fput:
 607         fput(file);
 608 error:
 609         cachefiles_do_unmark_inode_in_use(object, d_inode(dentry));
 610         dput(dentry);
 611         return false;
 612 }
 613
 614 /*
 615  * walk from the parent object to the child object through the backing
 616  * filesystem, creating directories as we go
 617  */
 618 bool cachefiles_look_up_object(struct cachefiles_object *object)
 619 {
 620         struct cachefiles_volume *volume = object->volume;
 621         struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash];
 622         int ret;
 623
 624         _enter("OBJ%x,%s,", object->debug_id, object->d_name);
 625
 626         /* Look up path "cache/vol/fanout/file". */
 627         ret = cachefiles_inject_read_error();
 628         if (ret == 0)
 629                 dentry = lookup_positive_unlocked(object->d_name, fan,
 630                                                   object->d_name_len);
 631         else
 632                 dentry = ERR_PTR(ret);
 633         trace_cachefiles_lookup(object, fan, dentry);
 634         if (IS_ERR(dentry)) {
 635                 if (dentry == ERR_PTR(-ENOENT))
 636                         goto new_file;
 637                 if (dentry == ERR_PTR(-EIO))
 638                         cachefiles_io_error_obj(object, "Lookup failed");
 639                 return false;
 640         }
 641
 642         if (!d_is_reg(dentry)) {
 643                 pr_err("%pd is not a file\n", dentry);
 644                 inode_lock_nested(d_inode(fan), I_MUTEX_PARENT);
 645                 ret = cachefiles_bury_object(volume->cache, object, fan, dentry,
 646                                              FSCACHE_OBJECT_IS_WEIRD);
 647                 dput(dentry);
 648                 if (ret < 0)
 649                         return false;
 650                 goto new_file;
 651         }
 652
 653         if (!cachefiles_open_file(object, dentry))
 654                 return false;
 655
 656         _leave(" = t [%lu]", file_inode(object->file)->i_ino);
 657         return true;
 658
 659 new_file:
 660         fscache_cookie_lookup_negative(object->cookie);
 661         return cachefiles_create_file(object);
 662 }
 663
 664 /*
 665  * Attempt to link a temporary file into its rightful place in the cache.
 666  */
 667 bool cachefiles_commit_tmpfile(struct cachefiles_cache *cache,
 668                                struct cachefiles_object *object)
 669 {
 670         struct cachefiles_volume *volume = object->volume;
 671         struct dentry *dentry, *fan = volume->fanout[(u8)object->cookie->key_hash];
 672         bool success = false;
 673         int ret;
 674
 675         _enter(",%pD", object->file);
 676
 677         inode_lock_nested(d_inode(fan), I_MUTEX_PARENT);
 678         ret = cachefiles_inject_read_error();
 679         if (ret == 0)
 680                 dentry = lookup_one_len(object->d_name, fan, object->d_name_len);
 681         else
 682                 dentry = ERR_PTR(ret);
 683         if (IS_ERR(dentry)) {
 684                 trace_cachefiles_vfs_error(object, d_inode(fan), PTR_ERR(dentry),
 685                                            cachefiles_trace_lookup_error);
 686                 _debug("lookup fail %ld", PTR_ERR(dentry));
 687                 goto out_unlock;
 688         }
 689
 690         if (!d_is_negative(dentry)) {
 691                 if (d_backing_inode(dentry) == file_inode(object->file)) {
 692                         success = true;
 693                         goto out_dput;
 694                 }
 695
 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_len(object->d_name, fan, object->d_name_len);
 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_len(filename, dir, strlen(filename));
 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 }