fs/cachefiles/namei.c

   1 /* CacheFiles path walking and related routines
   2  *
   3  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   4  * Written by David Howells (dhowells@redhat.com)
   5  *
   6  * This program is free software; you can redistribute it and/or
   7  * modify it under the terms of the GNU General Public Licence
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the Licence, or (at your option) any later version.
  10  */
  11
  12 #include <linux/module.h>
  13 #include <linux/sched.h>
  14 #include <linux/file.h>
  15 #include <linux/fs.h>
  16 #include <linux/fsnotify.h>
  17 #include <linux/quotaops.h>
  18 #include <linux/xattr.h>
  19 #include <linux/mount.h>
  20 #include <linux/namei.h>
  21 #include <linux/security.h>
  22 #include "internal.h"
  23
  24 static int cachefiles_wait_bit(void *flags)
  25 {
  26         schedule();
  27         return 0;
  28 }
  29
  30 /*
  31  * record the fact that an object is now active
  32  */
  33 static void cachefiles_mark_object_active(struct cachefiles_cache *cache,
  34                                           struct cachefiles_object *object)
  35 {
  36         struct cachefiles_object *xobject;
  37         struct rb_node **_p, *_parent = NULL;
  38         struct dentry *dentry;
  39
  40         _enter(",%p", object);
  41
  42 try_again:
  43         write_lock(&cache->active_lock);
  44
  45         if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags))
  46                 BUG();
  47
  48         dentry = object->dentry;
  49         _p = &cache->active_nodes.rb_node;
  50         while (*_p) {
  51                 _parent = *_p;
  52                 xobject = rb_entry(_parent,
  53                                    struct cachefiles_object, active_node);
  54
  55                 ASSERT(xobject != object);
  56
  57                 if (xobject->dentry > dentry)
  58                         _p = &(*_p)->rb_left;
  59                 else if (xobject->dentry < dentry)
  60                         _p = &(*_p)->rb_right;
  61                 else
  62                         goto wait_for_old_object;
  63         }
  64
  65         rb_link_node(&object->active_node, _parent, _p);
  66         rb_insert_color(&object->active_node, &cache->active_nodes);
  67
  68         write_unlock(&cache->active_lock);
  69         _leave("");
  70         return;
  71
  72         /* an old object from a previous incarnation is hogging the slot - we
  73          * need to wait for it to be destroyed */
  74 wait_for_old_object:
  75         if (xobject->fscache.state < FSCACHE_OBJECT_DYING) {
  76                 printk(KERN_ERR "\n");
  77                 printk(KERN_ERR "CacheFiles: Error:"
  78                        " Unexpected object collision\n");
  79                 printk(KERN_ERR "xobject: OBJ%x\n",
  80                        xobject->fscache.debug_id);
  81                 printk(KERN_ERR "xobjstate=%s\n",
  82                        fscache_object_states[xobject->fscache.state]);
  83                 printk(KERN_ERR "xobjflags=%lx\n", xobject->fscache.flags);
  84                 printk(KERN_ERR "xobjevent=%lx [%lx]\n",
  85                        xobject->fscache.events, xobject->fscache.event_mask);
  86                 printk(KERN_ERR "xops=%u inp=%u exc=%u\n",
  87                        xobject->fscache.n_ops, xobject->fscache.n_in_progress,
  88                        xobject->fscache.n_exclusive);
  89                 printk(KERN_ERR "xcookie=%p [pr=%p nd=%p fl=%lx]\n",
  90                        xobject->fscache.cookie,
  91                        xobject->fscache.cookie->parent,
  92                        xobject->fscache.cookie->netfs_data,
  93                        xobject->fscache.cookie->flags);
  94                 printk(KERN_ERR "xparent=%p\n",
  95                        xobject->fscache.parent);
  96                 printk(KERN_ERR "object: OBJ%x\n",
  97                        object->fscache.debug_id);
  98                 printk(KERN_ERR "cookie=%p [pr=%p nd=%p fl=%lx]\n",
  99                        object->fscache.cookie,
 100                        object->fscache.cookie->parent,
 101                        object->fscache.cookie->netfs_data,
 102                        object->fscache.cookie->flags);
 103                 printk(KERN_ERR "parent=%p\n",
 104                        object->fscache.parent);
 105                 BUG();
 106         }
 107         atomic_inc(&xobject->usage);
 108         write_unlock(&cache->active_lock);
 109
 110         _debug(">>> wait");
 111         wait_on_bit(&xobject->flags, CACHEFILES_OBJECT_ACTIVE,
 112                     cachefiles_wait_bit, TASK_UNINTERRUPTIBLE);
 113         _debug("<<< waited");
 114
 115         cache->cache.ops->put_object(&xobject->fscache);
 116         goto try_again;
 117 }
 118
 119 /*
 120  * delete an object representation from the cache
 121  * - file backed objects are unlinked
 122  * - directory backed objects are stuffed into the graveyard for userspace to
 123  *   delete
 124  * - unlocks the directory mutex
 125  */
 126 static int cachefiles_bury_object(struct cachefiles_cache *cache,
 127                                   struct dentry *dir,
 128                                   struct dentry *rep)
 129 {
 130         struct dentry *grave, *trap;
 131         char nbuffer[8 + 8 + 1];
 132         int ret;
 133
 134         _enter(",'%*.*s','%*.*s'",
 135                dir->d_name.len, dir->d_name.len, dir->d_name.name,
 136                rep->d_name.len, rep->d_name.len, rep->d_name.name);
 137
 138         /* non-directories can just be unlinked */
 139         if (!S_ISDIR(rep->d_inode->i_mode)) {
 140                 _debug("unlink stale object");
 141                 ret = vfs_unlink(dir->d_inode, rep);
 142
 143                 mutex_unlock(&dir->d_inode->i_mutex);
 144
 145                 if (ret == -EIO)
 146                         cachefiles_io_error(cache, "Unlink failed");
 147
 148                 _leave(" = %d", ret);
 149                 return ret;
 150         }
 151
 152         /* directories have to be moved to the graveyard */
 153         _debug("move stale object to graveyard");
 154         mutex_unlock(&dir->d_inode->i_mutex);
 155
 156 try_again:
 157         /* first step is to make up a grave dentry in the graveyard */
 158         sprintf(nbuffer, "%08x%08x",
 159                 (uint32_t) get_seconds(),
 160                 (uint32_t) atomic_inc_return(&cache->gravecounter));
 161
 162         /* do the multiway lock magic */
 163         trap = lock_rename(cache->graveyard, dir);
 164
 165         /* do some checks before getting the grave dentry */
 166         if (rep->d_parent != dir) {
 167                 /* the entry was probably culled when we dropped the parent dir
 168                  * lock */
 169                 unlock_rename(cache->graveyard, dir);
 170                 _leave(" = 0 [culled?]");
 171                 return 0;
 172         }
 173
 174         if (!S_ISDIR(cache->graveyard->d_inode->i_mode)) {
 175                 unlock_rename(cache->graveyard, dir);
 176                 cachefiles_io_error(cache, "Graveyard no longer a directory");
 177                 return -EIO;
 178         }
 179
 180         if (trap == rep) {
 181                 unlock_rename(cache->graveyard, dir);
 182                 cachefiles_io_error(cache, "May not make directory loop");
 183                 return -EIO;
 184         }
 185
 186         if (d_mountpoint(rep)) {
 187                 unlock_rename(cache->graveyard, dir);
 188                 cachefiles_io_error(cache, "Mountpoint in cache");
 189                 return -EIO;
 190         }
 191
 192         grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
 193         if (IS_ERR(grave)) {
 194                 unlock_rename(cache->graveyard, dir);
 195
 196                 if (PTR_ERR(grave) == -ENOMEM) {
 197                         _leave(" = -ENOMEM");
 198                         return -ENOMEM;
 199                 }
 200
 201                 cachefiles_io_error(cache, "Lookup error %ld",
 202                                     PTR_ERR(grave));
 203                 return -EIO;
 204         }
 205
 206         if (grave->d_inode) {
 207                 unlock_rename(cache->graveyard, dir);
 208                 dput(grave);
 209                 grave = NULL;
 210                 cond_resched();
 211                 goto try_again;
 212         }
 213
 214         if (d_mountpoint(grave)) {
 215                 unlock_rename(cache->graveyard, dir);
 216                 dput(grave);
 217                 cachefiles_io_error(cache, "Mountpoint in graveyard");
 218                 return -EIO;
 219         }
 220
 221         /* target should not be an ancestor of source */
 222         if (trap == grave) {
 223                 unlock_rename(cache->graveyard, dir);
 224                 dput(grave);
 225                 cachefiles_io_error(cache, "May not make directory loop");
 226                 return -EIO;
 227         }
 228
 229         /* attempt the rename */
 230         ret = vfs_rename(dir->d_inode, rep, cache->graveyard->d_inode, grave);
 231         if (ret != 0 && ret != -ENOMEM)
 232                 cachefiles_io_error(cache, "Rename failed with error %d", ret);
 233
 234         unlock_rename(cache->graveyard, dir);
 235         dput(grave);
 236         _leave(" = 0");
 237         return 0;
 238 }
 239
 240 /*
 241  * delete an object representation from the cache
 242  */
 243 int cachefiles_delete_object(struct cachefiles_cache *cache,
 244                              struct cachefiles_object *object)
 245 {
 246         struct dentry *dir;
 247         int ret;
 248
 249         _enter(",{%p}", object->dentry);
 250
 251         ASSERT(object->dentry);
 252         ASSERT(object->dentry->d_inode);
 253         ASSERT(object->dentry->d_parent);
 254
 255         dir = dget_parent(object->dentry);
 256
 257         mutex_lock(&dir->d_inode->i_mutex);
 258         ret = cachefiles_bury_object(cache, dir, object->dentry);
 259
 260         dput(dir);
 261         _leave(" = %d", ret);
 262         return ret;
 263 }
 264
 265 /*
 266  * walk from the parent object to the child object through the backing
 267  * filesystem, creating directories as we go
 268  */
 269 int cachefiles_walk_to_object(struct cachefiles_object *parent,
 270                               struct cachefiles_object *object,
 271                               const char *key,
 272                               struct cachefiles_xattr *auxdata)
 273 {
 274         struct cachefiles_cache *cache;
 275         struct dentry *dir, *next = NULL;
 276         unsigned long start;
 277         const char *name;
 278         int ret, nlen;
 279
 280         _enter("{%p},,%s,", parent->dentry, key);
 281
 282         cache = container_of(parent->fscache.cache,
 283                              struct cachefiles_cache, cache);
 284
 285         ASSERT(parent->dentry);
 286         ASSERT(parent->dentry->d_inode);
 287
 288         if (!(S_ISDIR(parent->dentry->d_inode->i_mode))) {
 289                 // TODO: convert file to dir
 290                 _leave("looking up in none directory");
 291                 return -ENOBUFS;
 292         }
 293
 294         dir = dget(parent->dentry);
 295
 296 advance:
 297         /* attempt to transit the first directory component */
 298         name = key;
 299         nlen = strlen(key);
 300
 301         /* key ends in a double NUL */
 302         key = key + nlen + 1;
 303         if (!*key)
 304                 key = NULL;
 305
 306 lookup_again:
 307         /* search the current directory for the element name */
 308         _debug("lookup '%s'", name);
 309
 310         mutex_lock(&dir->d_inode->i_mutex);
 311
 312         start = jiffies;
 313         next = lookup_one_len(name, dir, nlen);
 314         cachefiles_hist(cachefiles_lookup_histogram, start);
 315         if (IS_ERR(next))
 316                 goto lookup_error;
 317
 318         _debug("next -> %p %s", next, next->d_inode ? "positive" : "negative");
 319
 320         if (!key)
 321                 object->new = !next->d_inode;
 322
 323         /* if this element of the path doesn't exist, then the lookup phase
 324          * failed, and we can release any readers in the certain knowledge that
 325          * there's nothing for them to actually read */
 326         if (!next->d_inode)
 327                 fscache_object_lookup_negative(&object->fscache);
 328
 329         /* we need to create the object if it's negative */
 330         if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
 331                 /* index objects and intervening tree levels must be subdirs */
 332                 if (!next->d_inode) {
 333                         ret = cachefiles_has_space(cache, 1, 0);
 334                         if (ret < 0)
 335                                 goto create_error;
 336
 337                         start = jiffies;
 338                         ret = vfs_mkdir(dir->d_inode, next, 0);
 339                         cachefiles_hist(cachefiles_mkdir_histogram, start);
 340                         if (ret < 0)
 341                                 goto create_error;
 342
 343                         ASSERT(next->d_inode);
 344
 345                         _debug("mkdir -> %p{%p{ino=%lu}}",
 346                                next, next->d_inode, next->d_inode->i_ino);
 347
 348                 } else if (!S_ISDIR(next->d_inode->i_mode)) {
 349                         kerror("inode %lu is not a directory",
 350                                next->d_inode->i_ino);
 351                         ret = -ENOBUFS;
 352                         goto error;
 353                 }
 354
 355         } else {
 356                 /* non-index objects start out life as files */
 357                 if (!next->d_inode) {
 358                         ret = cachefiles_has_space(cache, 1, 0);
 359                         if (ret < 0)
 360                                 goto create_error;
 361
 362                         start = jiffies;
 363                         ret = vfs_create(dir->d_inode, next, S_IFREG, NULL);
 364                         cachefiles_hist(cachefiles_create_histogram, start);
 365                         if (ret < 0)
 366                                 goto create_error;
 367
 368                         ASSERT(next->d_inode);
 369
 370                         _debug("create -> %p{%p{ino=%lu}}",
 371                                next, next->d_inode, next->d_inode->i_ino);
 372
 373                 } else if (!S_ISDIR(next->d_inode->i_mode) &&
 374                            !S_ISREG(next->d_inode->i_mode)
 375                            ) {
 376                         kerror("inode %lu is not a file or directory",
 377                                next->d_inode->i_ino);
 378                         ret = -ENOBUFS;
 379                         goto error;
 380                 }
 381         }
 382
 383         /* process the next component */
 384         if (key) {
 385                 _debug("advance");
 386                 mutex_unlock(&dir->d_inode->i_mutex);
 387                 dput(dir);
 388                 dir = next;
 389                 next = NULL;
 390                 goto advance;
 391         }
 392
 393         /* we've found the object we were looking for */
 394         object->dentry = next;
 395
 396         /* if we've found that the terminal object exists, then we need to
 397          * check its attributes and delete it if it's out of date */
 398         if (!object->new) {
 399                 _debug("validate '%*.*s'",
 400                        next->d_name.len, next->d_name.len, next->d_name.name);
 401
 402                 ret = cachefiles_check_object_xattr(object, auxdata);
 403                 if (ret == -ESTALE) {
 404                         /* delete the object (the deleter drops the directory
 405                          * mutex) */
 406                         object->dentry = NULL;
 407
 408                         ret = cachefiles_bury_object(cache, dir, next);
 409                         dput(next);
 410                         next = NULL;
 411
 412                         if (ret < 0)
 413                                 goto delete_error;
 414
 415                         _debug("redo lookup");
 416                         goto lookup_again;
 417                 }
 418         }
 419
 420         /* note that we're now using this object */
 421         cachefiles_mark_object_active(cache, object);
 422
 423         mutex_unlock(&dir->d_inode->i_mutex);
 424         dput(dir);
 425         dir = NULL;
 426
 427         _debug("=== OBTAINED_OBJECT ===");
 428
 429         if (object->new) {
 430                 /* attach data to a newly constructed terminal object */
 431                 ret = cachefiles_set_object_xattr(object, auxdata);
 432                 if (ret < 0)
 433                         goto check_error;
 434         } else {
 435                 /* always update the atime on an object we've just looked up
 436                  * (this is used to keep track of culling, and atimes are only
 437                  * updated by read, write and readdir but not lookup or
 438                  * open) */
 439                 touch_atime(cache->mnt, next);
 440         }
 441
 442         /* open a file interface onto a data file */
 443         if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
 444                 if (S_ISREG(object->dentry->d_inode->i_mode)) {
 445                         const struct address_space_operations *aops;
 446
 447                         ret = -EPERM;
 448                         aops = object->dentry->d_inode->i_mapping->a_ops;
 449                         if (!aops->bmap)
 450                                 goto check_error;
 451
 452                         object->backer = object->dentry;
 453                 } else {
 454                         BUG(); // TODO: open file in data-class subdir
 455                 }
 456         }
 457
 458         object->new = 0;
 459         fscache_obtained_object(&object->fscache);
 460
 461         _leave(" = 0 [%lu]", object->dentry->d_inode->i_ino);
 462         return 0;
 463
 464 create_error:
 465         _debug("create error %d", ret);
 466         if (ret == -EIO)
 467                 cachefiles_io_error(cache, "Create/mkdir failed");
 468         goto error;
 469
 470 check_error:
 471         _debug("check error %d", ret);
 472         write_lock(&cache->active_lock);
 473         rb_erase(&object->active_node, &cache->active_nodes);
 474         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 475         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
 476         write_unlock(&cache->active_lock);
 477
 478         dput(object->dentry);
 479         object->dentry = NULL;
 480         goto error_out;
 481
 482 delete_error:
 483         _debug("delete error %d", ret);
 484         goto error_out2;
 485
 486 lookup_error:
 487         _debug("lookup error %ld", PTR_ERR(next));
 488         ret = PTR_ERR(next);
 489         if (ret == -EIO)
 490                 cachefiles_io_error(cache, "Lookup failed");
 491         next = NULL;
 492 error:
 493         mutex_unlock(&dir->d_inode->i_mutex);
 494         dput(next);
 495 error_out2:
 496         dput(dir);
 497 error_out:
 498         if (ret == -ENOSPC)
 499                 ret = -ENOBUFS;
 500
 501         _leave(" = error %d", -ret);
 502         return ret;
 503 }
 504
 505 /*
 506  * get a subdirectory
 507  */
 508 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
 509                                         struct dentry *dir,
 510                                         const char *dirname)
 511 {
 512         struct dentry *subdir;
 513         unsigned long start;
 514         int ret;
 515
 516         _enter(",,%s", dirname);
 517
 518         /* search the current directory for the element name */
 519         mutex_lock(&dir->d_inode->i_mutex);
 520
 521         start = jiffies;
 522         subdir = lookup_one_len(dirname, dir, strlen(dirname));
 523         cachefiles_hist(cachefiles_lookup_histogram, start);
 524         if (IS_ERR(subdir)) {
 525                 if (PTR_ERR(subdir) == -ENOMEM)
 526                         goto nomem_d_alloc;
 527                 goto lookup_error;
 528         }
 529
 530         _debug("subdir -> %p %s",
 531                subdir, subdir->d_inode ? "positive" : "negative");
 532
 533         /* we need to create the subdir if it doesn't exist yet */
 534         if (!subdir->d_inode) {
 535                 ret = cachefiles_has_space(cache, 1, 0);
 536                 if (ret < 0)
 537                         goto mkdir_error;
 538
 539                 _debug("attempt mkdir");
 540
 541                 ret = vfs_mkdir(dir->d_inode, subdir, 0700);
 542                 if (ret < 0)
 543                         goto mkdir_error;
 544
 545                 ASSERT(subdir->d_inode);
 546
 547                 _debug("mkdir -> %p{%p{ino=%lu}}",
 548                        subdir,
 549                        subdir->d_inode,
 550                        subdir->d_inode->i_ino);
 551         }
 552
 553         mutex_unlock(&dir->d_inode->i_mutex);
 554
 555         /* we need to make sure the subdir is a directory */
 556         ASSERT(subdir->d_inode);
 557
 558         if (!S_ISDIR(subdir->d_inode->i_mode)) {
 559                 kerror("%s is not a directory", dirname);
 560                 ret = -EIO;
 561                 goto check_error;
 562         }
 563
 564         ret = -EPERM;
 565         if (!subdir->d_inode->i_op ||
 566             !subdir->d_inode->i_op->setxattr ||
 567             !subdir->d_inode->i_op->getxattr ||
 568             !subdir->d_inode->i_op->lookup ||
 569             !subdir->d_inode->i_op->mkdir ||
 570             !subdir->d_inode->i_op->create ||
 571             !subdir->d_inode->i_op->rename ||
 572             !subdir->d_inode->i_op->rmdir ||
 573             !subdir->d_inode->i_op->unlink)
 574                 goto check_error;
 575
 576         _leave(" = [%lu]", subdir->d_inode->i_ino);
 577         return subdir;
 578
 579 check_error:
 580         dput(subdir);
 581         _leave(" = %d [check]", ret);
 582         return ERR_PTR(ret);
 583
 584 mkdir_error:
 585         mutex_unlock(&dir->d_inode->i_mutex);
 586         dput(subdir);
 587         kerror("mkdir %s failed with error %d", dirname, ret);
 588         return ERR_PTR(ret);
 589
 590 lookup_error:
 591         mutex_unlock(&dir->d_inode->i_mutex);
 592         ret = PTR_ERR(subdir);
 593         kerror("Lookup %s failed with error %d", dirname, ret);
 594         return ERR_PTR(ret);
 595
 596 nomem_d_alloc:
 597         mutex_unlock(&dir->d_inode->i_mutex);
 598         _leave(" = -ENOMEM");
 599         return ERR_PTR(-ENOMEM);
 600 }
 601
 602 /*
 603  * find out if an object is in use or not
 604  * - if finds object and it's not in use:
 605  *   - returns a pointer to the object and a reference on it
 606  *   - returns with the directory locked
 607  */
 608 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
 609                                               struct dentry *dir,
 610                                               char *filename)
 611 {
 612         struct cachefiles_object *object;
 613         struct rb_node *_n;
 614         struct dentry *victim;
 615         unsigned long start;
 616         int ret;
 617
 618         //_enter(",%*.*s/,%s",
 619         //       dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 620
 621         /* look up the victim */
 622         mutex_lock_nested(&dir->d_inode->i_mutex, 1);
 623
 624         start = jiffies;
 625         victim = lookup_one_len(filename, dir, strlen(filename));
 626         cachefiles_hist(cachefiles_lookup_histogram, start);
 627         if (IS_ERR(victim))
 628                 goto lookup_error;
 629
 630         //_debug("victim -> %p %s",
 631         //       victim, victim->d_inode ? "positive" : "negative");
 632
 633         /* if the object is no longer there then we probably retired the object
 634          * at the netfs's request whilst the cull was in progress
 635          */
 636         if (!victim->d_inode) {
 637                 mutex_unlock(&dir->d_inode->i_mutex);
 638                 dput(victim);
 639                 _leave(" = -ENOENT [absent]");
 640                 return ERR_PTR(-ENOENT);
 641         }
 642
 643         /* check to see if we're using this object */
 644         read_lock(&cache->active_lock);
 645
 646         _n = cache->active_nodes.rb_node;
 647
 648         while (_n) {
 649                 object = rb_entry(_n, struct cachefiles_object, active_node);
 650
 651                 if (object->dentry > victim)
 652                         _n = _n->rb_left;
 653                 else if (object->dentry < victim)
 654                         _n = _n->rb_right;
 655                 else
 656                         goto object_in_use;
 657         }
 658
 659         read_unlock(&cache->active_lock);
 660
 661         //_leave(" = %p", victim);
 662         return victim;
 663
 664 object_in_use:
 665         read_unlock(&cache->active_lock);
 666         mutex_unlock(&dir->d_inode->i_mutex);
 667         dput(victim);
 668         //_leave(" = -EBUSY [in use]");
 669         return ERR_PTR(-EBUSY);
 670
 671 lookup_error:
 672         mutex_unlock(&dir->d_inode->i_mutex);
 673         ret = PTR_ERR(victim);
 674         if (ret == -ENOENT) {
 675                 /* file or dir now absent - probably retired by netfs */
 676                 _leave(" = -ESTALE [absent]");
 677                 return ERR_PTR(-ESTALE);
 678         }
 679
 680         if (ret == -EIO) {
 681                 cachefiles_io_error(cache, "Lookup failed");
 682         } else if (ret != -ENOMEM) {
 683                 kerror("Internal error: %d", ret);
 684                 ret = -EIO;
 685         }
 686
 687         _leave(" = %d", ret);
 688         return ERR_PTR(ret);
 689 }
 690
 691 /*
 692  * cull an object if it's not in use
 693  * - called only by cache manager daemon
 694  */
 695 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
 696                     char *filename)
 697 {
 698         struct dentry *victim;
 699         int ret;
 700
 701         _enter(",%*.*s/,%s",
 702                dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 703
 704         victim = cachefiles_check_active(cache, dir, filename);
 705         if (IS_ERR(victim))
 706                 return PTR_ERR(victim);
 707
 708         _debug("victim -> %p %s",
 709                victim, victim->d_inode ? "positive" : "negative");
 710
 711         /* okay... the victim is not being used so we can cull it
 712          * - start by marking it as stale
 713          */
 714         _debug("victim is cullable");
 715
 716         ret = cachefiles_remove_object_xattr(cache, victim);
 717         if (ret < 0)
 718                 goto error_unlock;
 719
 720         /*  actually remove the victim (drops the dir mutex) */
 721         _debug("bury");
 722
 723         ret = cachefiles_bury_object(cache, dir, victim);
 724         if (ret < 0)
 725                 goto error;
 726
 727         dput(victim);
 728         _leave(" = 0");
 729         return 0;
 730
 731 error_unlock:
 732         mutex_unlock(&dir->d_inode->i_mutex);
 733 error:
 734         dput(victim);
 735         if (ret == -ENOENT) {
 736                 /* file or dir now absent - probably retired by netfs */
 737                 _leave(" = -ESTALE [absent]");
 738                 return -ESTALE;
 739         }
 740
 741         if (ret != -ENOMEM) {
 742                 kerror("Internal error: %d", ret);
 743                 ret = -EIO;
 744         }
 745
 746         _leave(" = %d", ret);
 747         return ret;
 748 }
 749
 750 /*
 751  * find out if an object is in use or not
 752  * - called only by cache manager daemon
 753  * - returns -EBUSY or 0 to indicate whether an object is in use or not
 754  */
 755 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
 756                             char *filename)
 757 {
 758         struct dentry *victim;
 759
 760         //_enter(",%*.*s/,%s",
 761         //       dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 762
 763         victim = cachefiles_check_active(cache, dir, filename);
 764         if (IS_ERR(victim))
 765                 return PTR_ERR(victim);
 766
 767         mutex_unlock(&dir->d_inode->i_mutex);
 768         dput(victim);
 769         //_leave(" = 0");
 770         return 0;
 771 }