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 #define CACHEFILES_KEYBUF_SIZE 512
  25
  26 /*
  27  * dump debugging info about an object
  28  */
  29 static noinline
  30 void __cachefiles_printk_object(struct cachefiles_object *object,
  31                                 const char *prefix,
  32                                 u8 *keybuf)
  33 {
  34         struct fscache_cookie *cookie;
  35         unsigned keylen, loop;
  36
  37         printk(KERN_ERR "%sobject: OBJ%x\n",
  38                prefix, object->fscache.debug_id);
  39         printk(KERN_ERR "%sobjstate=%s fl=%lx swfl=%lx ev=%lx[%lx]\n",
  40                prefix, fscache_object_states[object->fscache.state],
  41                object->fscache.flags, object->fscache.work.flags,
  42                object->fscache.events,
  43                object->fscache.event_mask & FSCACHE_OBJECT_EVENTS_MASK);
  44         printk(KERN_ERR "%sops=%u inp=%u exc=%u\n",
  45                prefix, object->fscache.n_ops, object->fscache.n_in_progress,
  46                object->fscache.n_exclusive);
  47         printk(KERN_ERR "%sparent=%p\n",
  48                prefix, object->fscache.parent);
  49
  50         spin_lock(&object->fscache.lock);
  51         cookie = object->fscache.cookie;
  52         if (cookie) {
  53                 printk(KERN_ERR "%scookie=%p [pr=%p nd=%p fl=%lx]\n",
  54                        prefix,
  55                        object->fscache.cookie,
  56                        object->fscache.cookie->parent,
  57                        object->fscache.cookie->netfs_data,
  58                        object->fscache.cookie->flags);
  59                 if (keybuf)
  60                         keylen = cookie->def->get_key(cookie->netfs_data, keybuf,
  61                                                       CACHEFILES_KEYBUF_SIZE);
  62                 else
  63                         keylen = 0;
  64         } else {
  65                 printk(KERN_ERR "%scookie=NULL\n", prefix);
  66                 keylen = 0;
  67         }
  68         spin_unlock(&object->fscache.lock);
  69
  70         if (keylen) {
  71                 printk(KERN_ERR "%skey=[%u] '", prefix, keylen);
  72                 for (loop = 0; loop < keylen; loop++)
  73                         printk("%02x", keybuf[loop]);
  74                 printk("'\n");
  75         }
  76 }
  77
  78 /*
  79  * dump debugging info about a pair of objects
  80  */
  81 static noinline void cachefiles_printk_object(struct cachefiles_object *object,
  82                                               struct cachefiles_object *xobject)
  83 {
  84         u8 *keybuf;
  85
  86         keybuf = kmalloc(CACHEFILES_KEYBUF_SIZE, GFP_NOIO);
  87         if (object)
  88                 __cachefiles_printk_object(object, "", keybuf);
  89         if (xobject)
  90                 __cachefiles_printk_object(xobject, "x", keybuf);
  91         kfree(keybuf);
  92 }
  93
  94 /*
  95  * record the fact that an object is now active
  96  */
  97 static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
  98                                          struct cachefiles_object *object)
  99 {
 100         struct cachefiles_object *xobject;
 101         struct rb_node **_p, *_parent = NULL;
 102         struct dentry *dentry;
 103
 104         _enter(",%p", object);
 105
 106 try_again:
 107         write_lock(&cache->active_lock);
 108
 109         if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
 110                 printk(KERN_ERR "CacheFiles: Error: Object already active\n");
 111                 cachefiles_printk_object(object, NULL);
 112                 BUG();
 113         }
 114
 115         dentry = object->dentry;
 116         _p = &cache->active_nodes.rb_node;
 117         while (*_p) {
 118                 _parent = *_p;
 119                 xobject = rb_entry(_parent,
 120                                    struct cachefiles_object, active_node);
 121
 122                 ASSERT(xobject != object);
 123
 124                 if (xobject->dentry > dentry)
 125                         _p = &(*_p)->rb_left;
 126                 else if (xobject->dentry < dentry)
 127                         _p = &(*_p)->rb_right;
 128                 else
 129                         goto wait_for_old_object;
 130         }
 131
 132         rb_link_node(&object->active_node, _parent, _p);
 133         rb_insert_color(&object->active_node, &cache->active_nodes);
 134
 135         write_unlock(&cache->active_lock);
 136         _leave(" = 0");
 137         return 0;
 138
 139         /* an old object from a previous incarnation is hogging the slot - we
 140          * need to wait for it to be destroyed */
 141 wait_for_old_object:
 142         if (xobject->fscache.state < FSCACHE_OBJECT_DYING) {
 143                 printk(KERN_ERR "\n");
 144                 printk(KERN_ERR "CacheFiles: Error:"
 145                        " Unexpected object collision\n");
 146                 cachefiles_printk_object(object, xobject);
 147                 BUG();
 148         }
 149         atomic_inc(&xobject->usage);
 150         write_unlock(&cache->active_lock);
 151
 152         if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 153                 wait_queue_head_t *wq;
 154
 155                 signed long timeout = 60 * HZ;
 156                 wait_queue_t wait;
 157                 bool requeue;
 158
 159                 /* if the object we're waiting for is queued for processing,
 160                  * then just put ourselves on the queue behind it */
 161                 if (slow_work_is_queued(&xobject->fscache.work)) {
 162                         _debug("queue OBJ%x behind OBJ%x immediately",
 163                                object->fscache.debug_id,
 164                                xobject->fscache.debug_id);
 165                         goto requeue;
 166                 }
 167
 168                 /* otherwise we sleep until either the object we're waiting for
 169                  * is done, or the slow-work facility wants the thread back to
 170                  * do other work */
 171                 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
 172                 init_wait(&wait);
 173                 requeue = false;
 174                 do {
 175                         prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
 176                         if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
 177                                 break;
 178                         requeue = slow_work_sleep_till_thread_needed(
 179                                 &object->fscache.work, &timeout);
 180                 } while (timeout > 0 && !requeue);
 181                 finish_wait(wq, &wait);
 182
 183                 if (requeue &&
 184                     test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 185                         _debug("queue OBJ%x behind OBJ%x after wait",
 186                                object->fscache.debug_id,
 187                                xobject->fscache.debug_id);
 188                         goto requeue;
 189                 }
 190
 191                 if (timeout <= 0) {
 192                         printk(KERN_ERR "\n");
 193                         printk(KERN_ERR "CacheFiles: Error: Overlong"
 194                                " wait for old active object to go away\n");
 195                         cachefiles_printk_object(object, xobject);
 196                         goto requeue;
 197                 }
 198         }
 199
 200         ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
 201
 202         cache->cache.ops->put_object(&xobject->fscache);
 203         goto try_again;
 204
 205 requeue:
 206         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 207         cache->cache.ops->put_object(&xobject->fscache);
 208         _leave(" = -ETIMEDOUT");
 209         return -ETIMEDOUT;
 210 }
 211
 212 /*
 213  * delete an object representation from the cache
 214  * - file backed objects are unlinked
 215  * - directory backed objects are stuffed into the graveyard for userspace to
 216  *   delete
 217  * - unlocks the directory mutex
 218  */
 219 static int cachefiles_bury_object(struct cachefiles_cache *cache,
 220                                   struct dentry *dir,
 221                                   struct dentry *rep)
 222 {
 223         struct dentry *grave, *trap;
 224         char nbuffer[8 + 8 + 1];
 225         int ret;
 226
 227         _enter(",'%*.*s','%*.*s'",
 228                dir->d_name.len, dir->d_name.len, dir->d_name.name,
 229                rep->d_name.len, rep->d_name.len, rep->d_name.name);
 230
 231         /* non-directories can just be unlinked */
 232         if (!S_ISDIR(rep->d_inode->i_mode)) {
 233                 _debug("unlink stale object");
 234                 ret = vfs_unlink(dir->d_inode, rep);
 235
 236                 mutex_unlock(&dir->d_inode->i_mutex);
 237
 238                 if (ret == -EIO)
 239                         cachefiles_io_error(cache, "Unlink failed");
 240
 241                 _leave(" = %d", ret);
 242                 return ret;
 243         }
 244
 245         /* directories have to be moved to the graveyard */
 246         _debug("move stale object to graveyard");
 247         mutex_unlock(&dir->d_inode->i_mutex);
 248
 249 try_again:
 250         /* first step is to make up a grave dentry in the graveyard */
 251         sprintf(nbuffer, "%08x%08x",
 252                 (uint32_t) get_seconds(),
 253                 (uint32_t) atomic_inc_return(&cache->gravecounter));
 254
 255         /* do the multiway lock magic */
 256         trap = lock_rename(cache->graveyard, dir);
 257
 258         /* do some checks before getting the grave dentry */
 259         if (rep->d_parent != dir) {
 260                 /* the entry was probably culled when we dropped the parent dir
 261                  * lock */
 262                 unlock_rename(cache->graveyard, dir);
 263                 _leave(" = 0 [culled?]");
 264                 return 0;
 265         }
 266
 267         if (!S_ISDIR(cache->graveyard->d_inode->i_mode)) {
 268                 unlock_rename(cache->graveyard, dir);
 269                 cachefiles_io_error(cache, "Graveyard no longer a directory");
 270                 return -EIO;
 271         }
 272
 273         if (trap == rep) {
 274                 unlock_rename(cache->graveyard, dir);
 275                 cachefiles_io_error(cache, "May not make directory loop");
 276                 return -EIO;
 277         }
 278
 279         if (d_mountpoint(rep)) {
 280                 unlock_rename(cache->graveyard, dir);
 281                 cachefiles_io_error(cache, "Mountpoint in cache");
 282                 return -EIO;
 283         }
 284
 285         grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
 286         if (IS_ERR(grave)) {
 287                 unlock_rename(cache->graveyard, dir);
 288
 289                 if (PTR_ERR(grave) == -ENOMEM) {
 290                         _leave(" = -ENOMEM");
 291                         return -ENOMEM;
 292                 }
 293
 294                 cachefiles_io_error(cache, "Lookup error %ld",
 295                                     PTR_ERR(grave));
 296                 return -EIO;
 297         }
 298
 299         if (grave->d_inode) {
 300                 unlock_rename(cache->graveyard, dir);
 301                 dput(grave);
 302                 grave = NULL;
 303                 cond_resched();
 304                 goto try_again;
 305         }
 306
 307         if (d_mountpoint(grave)) {
 308                 unlock_rename(cache->graveyard, dir);
 309                 dput(grave);
 310                 cachefiles_io_error(cache, "Mountpoint in graveyard");
 311                 return -EIO;
 312         }
 313
 314         /* target should not be an ancestor of source */
 315         if (trap == grave) {
 316                 unlock_rename(cache->graveyard, dir);
 317                 dput(grave);
 318                 cachefiles_io_error(cache, "May not make directory loop");
 319                 return -EIO;
 320         }
 321
 322         /* attempt the rename */
 323         ret = vfs_rename(dir->d_inode, rep, cache->graveyard->d_inode, grave);
 324         if (ret != 0 && ret != -ENOMEM)
 325                 cachefiles_io_error(cache, "Rename failed with error %d", ret);
 326
 327         unlock_rename(cache->graveyard, dir);
 328         dput(grave);
 329         _leave(" = 0");
 330         return 0;
 331 }
 332
 333 /*
 334  * delete an object representation from the cache
 335  */
 336 int cachefiles_delete_object(struct cachefiles_cache *cache,
 337                              struct cachefiles_object *object)
 338 {
 339         struct dentry *dir;
 340         int ret;
 341
 342         _enter(",{%p}", object->dentry);
 343
 344         ASSERT(object->dentry);
 345         ASSERT(object->dentry->d_inode);
 346         ASSERT(object->dentry->d_parent);
 347
 348         dir = dget_parent(object->dentry);
 349
 350         mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 351
 352         /* we need to check that our parent is _still_ our parent - it may have
 353          * been renamed */
 354         if (dir == object->dentry->d_parent) {
 355                 ret = cachefiles_bury_object(cache, dir, object->dentry);
 356         } else {
 357                 /* it got moved, presumably by cachefilesd culling it, so it's
 358                  * no longer in the key path and we can ignore it */
 359                 mutex_unlock(&dir->d_inode->i_mutex);
 360                 ret = 0;
 361         }
 362
 363         dput(dir);
 364         _leave(" = %d", ret);
 365         return ret;
 366 }
 367
 368 /*
 369  * walk from the parent object to the child object through the backing
 370  * filesystem, creating directories as we go
 371  */
 372 int cachefiles_walk_to_object(struct cachefiles_object *parent,
 373                               struct cachefiles_object *object,
 374                               const char *key,
 375                               struct cachefiles_xattr *auxdata)
 376 {
 377         struct cachefiles_cache *cache;
 378         struct dentry *dir, *next = NULL;
 379         unsigned long start;
 380         const char *name;
 381         int ret, nlen;
 382
 383         _enter("{%p},,%s,", parent->dentry, key);
 384
 385         cache = container_of(parent->fscache.cache,
 386                              struct cachefiles_cache, cache);
 387
 388         ASSERT(parent->dentry);
 389         ASSERT(parent->dentry->d_inode);
 390
 391         if (!(S_ISDIR(parent->dentry->d_inode->i_mode))) {
 392                 // TODO: convert file to dir
 393                 _leave("looking up in none directory");
 394                 return -ENOBUFS;
 395         }
 396
 397         dir = dget(parent->dentry);
 398
 399 advance:
 400         /* attempt to transit the first directory component */
 401         name = key;
 402         nlen = strlen(key);
 403
 404         /* key ends in a double NUL */
 405         key = key + nlen + 1;
 406         if (!*key)
 407                 key = NULL;
 408
 409 lookup_again:
 410         /* search the current directory for the element name */
 411         _debug("lookup '%s'", name);
 412
 413         mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 414
 415         start = jiffies;
 416         next = lookup_one_len(name, dir, nlen);
 417         cachefiles_hist(cachefiles_lookup_histogram, start);
 418         if (IS_ERR(next))
 419                 goto lookup_error;
 420
 421         _debug("next -> %p %s", next, next->d_inode ? "positive" : "negative");
 422
 423         if (!key)
 424                 object->new = !next->d_inode;
 425
 426         /* if this element of the path doesn't exist, then the lookup phase
 427          * failed, and we can release any readers in the certain knowledge that
 428          * there's nothing for them to actually read */
 429         if (!next->d_inode)
 430                 fscache_object_lookup_negative(&object->fscache);
 431
 432         /* we need to create the object if it's negative */
 433         if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
 434                 /* index objects and intervening tree levels must be subdirs */
 435                 if (!next->d_inode) {
 436                         ret = cachefiles_has_space(cache, 1, 0);
 437                         if (ret < 0)
 438                                 goto create_error;
 439
 440                         start = jiffies;
 441                         ret = vfs_mkdir(dir->d_inode, next, 0);
 442                         cachefiles_hist(cachefiles_mkdir_histogram, start);
 443                         if (ret < 0)
 444                                 goto create_error;
 445
 446                         ASSERT(next->d_inode);
 447
 448                         _debug("mkdir -> %p{%p{ino=%lu}}",
 449                                next, next->d_inode, next->d_inode->i_ino);
 450
 451                 } else if (!S_ISDIR(next->d_inode->i_mode)) {
 452                         kerror("inode %lu is not a directory",
 453                                next->d_inode->i_ino);
 454                         ret = -ENOBUFS;
 455                         goto error;
 456                 }
 457
 458         } else {
 459                 /* non-index objects start out life as files */
 460                 if (!next->d_inode) {
 461                         ret = cachefiles_has_space(cache, 1, 0);
 462                         if (ret < 0)
 463                                 goto create_error;
 464
 465                         start = jiffies;
 466                         ret = vfs_create(dir->d_inode, next, S_IFREG, NULL);
 467                         cachefiles_hist(cachefiles_create_histogram, start);
 468                         if (ret < 0)
 469                                 goto create_error;
 470
 471                         ASSERT(next->d_inode);
 472
 473                         _debug("create -> %p{%p{ino=%lu}}",
 474                                next, next->d_inode, next->d_inode->i_ino);
 475
 476                 } else if (!S_ISDIR(next->d_inode->i_mode) &&
 477                            !S_ISREG(next->d_inode->i_mode)
 478                            ) {
 479                         kerror("inode %lu is not a file or directory",
 480                                next->d_inode->i_ino);
 481                         ret = -ENOBUFS;
 482                         goto error;
 483                 }
 484         }
 485
 486         /* process the next component */
 487         if (key) {
 488                 _debug("advance");
 489                 mutex_unlock(&dir->d_inode->i_mutex);
 490                 dput(dir);
 491                 dir = next;
 492                 next = NULL;
 493                 goto advance;
 494         }
 495
 496         /* we've found the object we were looking for */
 497         object->dentry = next;
 498
 499         /* if we've found that the terminal object exists, then we need to
 500          * check its attributes and delete it if it's out of date */
 501         if (!object->new) {
 502                 _debug("validate '%*.*s'",
 503                        next->d_name.len, next->d_name.len, next->d_name.name);
 504
 505                 ret = cachefiles_check_object_xattr(object, auxdata);
 506                 if (ret == -ESTALE) {
 507                         /* delete the object (the deleter drops the directory
 508                          * mutex) */
 509                         object->dentry = NULL;
 510
 511                         ret = cachefiles_bury_object(cache, dir, next);
 512                         dput(next);
 513                         next = NULL;
 514
 515                         if (ret < 0)
 516                                 goto delete_error;
 517
 518                         _debug("redo lookup");
 519                         goto lookup_again;
 520                 }
 521         }
 522
 523         /* note that we're now using this object */
 524         ret = cachefiles_mark_object_active(cache, object);
 525
 526         mutex_unlock(&dir->d_inode->i_mutex);
 527         dput(dir);
 528         dir = NULL;
 529
 530         if (ret == -ETIMEDOUT)
 531                 goto mark_active_timed_out;
 532
 533         _debug("=== OBTAINED_OBJECT ===");
 534
 535         if (object->new) {
 536                 /* attach data to a newly constructed terminal object */
 537                 ret = cachefiles_set_object_xattr(object, auxdata);
 538                 if (ret < 0)
 539                         goto check_error;
 540         } else {
 541                 /* always update the atime on an object we've just looked up
 542                  * (this is used to keep track of culling, and atimes are only
 543                  * updated by read, write and readdir but not lookup or
 544                  * open) */
 545                 touch_atime(cache->mnt, next);
 546         }
 547
 548         /* open a file interface onto a data file */
 549         if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
 550                 if (S_ISREG(object->dentry->d_inode->i_mode)) {
 551                         const struct address_space_operations *aops;
 552
 553                         ret = -EPERM;
 554                         aops = object->dentry->d_inode->i_mapping->a_ops;
 555                         if (!aops->bmap)
 556                                 goto check_error;
 557
 558                         object->backer = object->dentry;
 559                 } else {
 560                         BUG(); // TODO: open file in data-class subdir
 561                 }
 562         }
 563
 564         object->new = 0;
 565         fscache_obtained_object(&object->fscache);
 566
 567         _leave(" = 0 [%lu]", object->dentry->d_inode->i_ino);
 568         return 0;
 569
 570 create_error:
 571         _debug("create error %d", ret);
 572         if (ret == -EIO)
 573                 cachefiles_io_error(cache, "Create/mkdir failed");
 574         goto error;
 575
 576 mark_active_timed_out:
 577         _debug("mark active timed out");
 578         goto release_dentry;
 579
 580 check_error:
 581         _debug("check error %d", ret);
 582         write_lock(&cache->active_lock);
 583         rb_erase(&object->active_node, &cache->active_nodes);
 584         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 585         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
 586         write_unlock(&cache->active_lock);
 587 release_dentry:
 588         dput(object->dentry);
 589         object->dentry = NULL;
 590         goto error_out;
 591
 592 delete_error:
 593         _debug("delete error %d", ret);
 594         goto error_out2;
 595
 596 lookup_error:
 597         _debug("lookup error %ld", PTR_ERR(next));
 598         ret = PTR_ERR(next);
 599         if (ret == -EIO)
 600                 cachefiles_io_error(cache, "Lookup failed");
 601         next = NULL;
 602 error:
 603         mutex_unlock(&dir->d_inode->i_mutex);
 604         dput(next);
 605 error_out2:
 606         dput(dir);
 607 error_out:
 608         _leave(" = error %d", -ret);
 609         return ret;
 610 }
 611
 612 /*
 613  * get a subdirectory
 614  */
 615 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
 616                                         struct dentry *dir,
 617                                         const char *dirname)
 618 {
 619         struct dentry *subdir;
 620         unsigned long start;
 621         int ret;
 622
 623         _enter(",,%s", dirname);
 624
 625         /* search the current directory for the element name */
 626         mutex_lock(&dir->d_inode->i_mutex);
 627
 628         start = jiffies;
 629         subdir = lookup_one_len(dirname, dir, strlen(dirname));
 630         cachefiles_hist(cachefiles_lookup_histogram, start);
 631         if (IS_ERR(subdir)) {
 632                 if (PTR_ERR(subdir) == -ENOMEM)
 633                         goto nomem_d_alloc;
 634                 goto lookup_error;
 635         }
 636
 637         _debug("subdir -> %p %s",
 638                subdir, subdir->d_inode ? "positive" : "negative");
 639
 640         /* we need to create the subdir if it doesn't exist yet */
 641         if (!subdir->d_inode) {
 642                 ret = cachefiles_has_space(cache, 1, 0);
 643                 if (ret < 0)
 644                         goto mkdir_error;
 645
 646                 _debug("attempt mkdir");
 647
 648                 ret = vfs_mkdir(dir->d_inode, subdir, 0700);
 649                 if (ret < 0)
 650                         goto mkdir_error;
 651
 652                 ASSERT(subdir->d_inode);
 653
 654                 _debug("mkdir -> %p{%p{ino=%lu}}",
 655                        subdir,
 656                        subdir->d_inode,
 657                        subdir->d_inode->i_ino);
 658         }
 659
 660         mutex_unlock(&dir->d_inode->i_mutex);
 661
 662         /* we need to make sure the subdir is a directory */
 663         ASSERT(subdir->d_inode);
 664
 665         if (!S_ISDIR(subdir->d_inode->i_mode)) {
 666                 kerror("%s is not a directory", dirname);
 667                 ret = -EIO;
 668                 goto check_error;
 669         }
 670
 671         ret = -EPERM;
 672         if (!subdir->d_inode->i_op ||
 673             !subdir->d_inode->i_op->setxattr ||
 674             !subdir->d_inode->i_op->getxattr ||
 675             !subdir->d_inode->i_op->lookup ||
 676             !subdir->d_inode->i_op->mkdir ||
 677             !subdir->d_inode->i_op->create ||
 678             !subdir->d_inode->i_op->rename ||
 679             !subdir->d_inode->i_op->rmdir ||
 680             !subdir->d_inode->i_op->unlink)
 681                 goto check_error;
 682
 683         _leave(" = [%lu]", subdir->d_inode->i_ino);
 684         return subdir;
 685
 686 check_error:
 687         dput(subdir);
 688         _leave(" = %d [check]", ret);
 689         return ERR_PTR(ret);
 690
 691 mkdir_error:
 692         mutex_unlock(&dir->d_inode->i_mutex);
 693         dput(subdir);
 694         kerror("mkdir %s failed with error %d", dirname, ret);
 695         return ERR_PTR(ret);
 696
 697 lookup_error:
 698         mutex_unlock(&dir->d_inode->i_mutex);
 699         ret = PTR_ERR(subdir);
 700         kerror("Lookup %s failed with error %d", dirname, ret);
 701         return ERR_PTR(ret);
 702
 703 nomem_d_alloc:
 704         mutex_unlock(&dir->d_inode->i_mutex);
 705         _leave(" = -ENOMEM");
 706         return ERR_PTR(-ENOMEM);
 707 }
 708
 709 /*
 710  * find out if an object is in use or not
 711  * - if finds object and it's not in use:
 712  *   - returns a pointer to the object and a reference on it
 713  *   - returns with the directory locked
 714  */
 715 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
 716                                               struct dentry *dir,
 717                                               char *filename)
 718 {
 719         struct cachefiles_object *object;
 720         struct rb_node *_n;
 721         struct dentry *victim;
 722         unsigned long start;
 723         int ret;
 724
 725         //_enter(",%*.*s/,%s",
 726         //       dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 727
 728         /* look up the victim */
 729         mutex_lock_nested(&dir->d_inode->i_mutex, 1);
 730
 731         start = jiffies;
 732         victim = lookup_one_len(filename, dir, strlen(filename));
 733         cachefiles_hist(cachefiles_lookup_histogram, start);
 734         if (IS_ERR(victim))
 735                 goto lookup_error;
 736
 737         //_debug("victim -> %p %s",
 738         //       victim, victim->d_inode ? "positive" : "negative");
 739
 740         /* if the object is no longer there then we probably retired the object
 741          * at the netfs's request whilst the cull was in progress
 742          */
 743         if (!victim->d_inode) {
 744                 mutex_unlock(&dir->d_inode->i_mutex);
 745                 dput(victim);
 746                 _leave(" = -ENOENT [absent]");
 747                 return ERR_PTR(-ENOENT);
 748         }
 749
 750         /* check to see if we're using this object */
 751         read_lock(&cache->active_lock);
 752
 753         _n = cache->active_nodes.rb_node;
 754
 755         while (_n) {
 756                 object = rb_entry(_n, struct cachefiles_object, active_node);
 757
 758                 if (object->dentry > victim)
 759                         _n = _n->rb_left;
 760                 else if (object->dentry < victim)
 761                         _n = _n->rb_right;
 762                 else
 763                         goto object_in_use;
 764         }
 765
 766         read_unlock(&cache->active_lock);
 767
 768         //_leave(" = %p", victim);
 769         return victim;
 770
 771 object_in_use:
 772         read_unlock(&cache->active_lock);
 773         mutex_unlock(&dir->d_inode->i_mutex);
 774         dput(victim);
 775         //_leave(" = -EBUSY [in use]");
 776         return ERR_PTR(-EBUSY);
 777
 778 lookup_error:
 779         mutex_unlock(&dir->d_inode->i_mutex);
 780         ret = PTR_ERR(victim);
 781         if (ret == -ENOENT) {
 782                 /* file or dir now absent - probably retired by netfs */
 783                 _leave(" = -ESTALE [absent]");
 784                 return ERR_PTR(-ESTALE);
 785         }
 786
 787         if (ret == -EIO) {
 788                 cachefiles_io_error(cache, "Lookup failed");
 789         } else if (ret != -ENOMEM) {
 790                 kerror("Internal error: %d", ret);
 791                 ret = -EIO;
 792         }
 793
 794         _leave(" = %d", ret);
 795         return ERR_PTR(ret);
 796 }
 797
 798 /*
 799  * cull an object if it's not in use
 800  * - called only by cache manager daemon
 801  */
 802 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
 803                     char *filename)
 804 {
 805         struct dentry *victim;
 806         int ret;
 807
 808         _enter(",%*.*s/,%s",
 809                dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 810
 811         victim = cachefiles_check_active(cache, dir, filename);
 812         if (IS_ERR(victim))
 813                 return PTR_ERR(victim);
 814
 815         _debug("victim -> %p %s",
 816                victim, victim->d_inode ? "positive" : "negative");
 817
 818         /* okay... the victim is not being used so we can cull it
 819          * - start by marking it as stale
 820          */
 821         _debug("victim is cullable");
 822
 823         ret = cachefiles_remove_object_xattr(cache, victim);
 824         if (ret < 0)
 825                 goto error_unlock;
 826
 827         /*  actually remove the victim (drops the dir mutex) */
 828         _debug("bury");
 829
 830         ret = cachefiles_bury_object(cache, dir, victim);
 831         if (ret < 0)
 832                 goto error;
 833
 834         dput(victim);
 835         _leave(" = 0");
 836         return 0;
 837
 838 error_unlock:
 839         mutex_unlock(&dir->d_inode->i_mutex);
 840 error:
 841         dput(victim);
 842         if (ret == -ENOENT) {
 843                 /* file or dir now absent - probably retired by netfs */
 844                 _leave(" = -ESTALE [absent]");
 845                 return -ESTALE;
 846         }
 847
 848         if (ret != -ENOMEM) {
 849                 kerror("Internal error: %d", ret);
 850                 ret = -EIO;
 851         }
 852
 853         _leave(" = %d", ret);
 854         return ret;
 855 }
 856
 857 /*
 858  * find out if an object is in use or not
 859  * - called only by cache manager daemon
 860  * - returns -EBUSY or 0 to indicate whether an object is in use or not
 861  */
 862 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
 863                             char *filename)
 864 {
 865         struct dentry *victim;
 866
 867         //_enter(",%*.*s/,%s",
 868         //       dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 869
 870         victim = cachefiles_check_active(cache, dir, filename);
 871         if (IS_ERR(victim))
 872                 return PTR_ERR(victim);
 873
 874         mutex_unlock(&dir->d_inode->i_mutex);
 875         dput(victim);
 876         //_leave(" = 0");
 877         return 0;
 878 }