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 <linux/slab.h>
  23 #include "internal.h"
  24
  25 #define CACHEFILES_KEYBUF_SIZE 512
  26
  27 /*
  28  * dump debugging info about an object
  29  */
  30 static noinline
  31 void __cachefiles_printk_object(struct cachefiles_object *object,
  32                                 const char *prefix,
  33                                 u8 *keybuf)
  34 {
  35         struct fscache_cookie *cookie;
  36         unsigned keylen, loop;
  37
  38         printk(KERN_ERR "%sobject: OBJ%x\n",
  39                prefix, object->fscache.debug_id);
  40         printk(KERN_ERR "%sobjstate=%s fl=%lx wbusy=%x ev=%lx[%lx]\n",
  41                prefix, fscache_object_states[object->fscache.state],
  42                object->fscache.flags, work_busy(&object->fscache.work),
  43                object->fscache.events,
  44                object->fscache.event_mask & FSCACHE_OBJECT_EVENTS_MASK);
  45         printk(KERN_ERR "%sops=%u inp=%u exc=%u\n",
  46                prefix, object->fscache.n_ops, object->fscache.n_in_progress,
  47                object->fscache.n_exclusive);
  48         printk(KERN_ERR "%sparent=%p\n",
  49                prefix, object->fscache.parent);
  50
  51         spin_lock(&object->fscache.lock);
  52         cookie = object->fscache.cookie;
  53         if (cookie) {
  54                 printk(KERN_ERR "%scookie=%p [pr=%p nd=%p fl=%lx]\n",
  55                        prefix,
  56                        object->fscache.cookie,
  57                        object->fscache.cookie->parent,
  58                        object->fscache.cookie->netfs_data,
  59                        object->fscache.cookie->flags);
  60                 if (keybuf)
  61                         keylen = cookie->def->get_key(cookie->netfs_data, keybuf,
  62                                                       CACHEFILES_KEYBUF_SIZE);
  63                 else
  64                         keylen = 0;
  65         } else {
  66                 printk(KERN_ERR "%scookie=NULL\n", prefix);
  67                 keylen = 0;
  68         }
  69         spin_unlock(&object->fscache.lock);
  70
  71         if (keylen) {
  72                 printk(KERN_ERR "%skey=[%u] '", prefix, keylen);
  73                 for (loop = 0; loop < keylen; loop++)
  74                         printk("%02x", keybuf[loop]);
  75                 printk("'\n");
  76         }
  77 }
  78
  79 /*
  80  * dump debugging info about a pair of objects
  81  */
  82 static noinline void cachefiles_printk_object(struct cachefiles_object *object,
  83                                               struct cachefiles_object *xobject)
  84 {
  85         u8 *keybuf;
  86
  87         keybuf = kmalloc(CACHEFILES_KEYBUF_SIZE, GFP_NOIO);
  88         if (object)
  89                 __cachefiles_printk_object(object, "", keybuf);
  90         if (xobject)
  91                 __cachefiles_printk_object(xobject, "x", keybuf);
  92         kfree(keybuf);
  93 }
  94
  95 /*
  96  * mark the owner of a dentry, if there is one, to indicate that that dentry
  97  * has been preemptively deleted
  98  * - the caller must hold the i_mutex on the dentry's parent as required to
  99  *   call vfs_unlink(), vfs_rmdir() or vfs_rename()
 100  */
 101 static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
 102                                           struct dentry *dentry)
 103 {
 104         struct cachefiles_object *object;
 105         struct rb_node *p;
 106
 107         _enter(",'%*.*s'",
 108                dentry->d_name.len, dentry->d_name.len, dentry->d_name.name);
 109
 110         write_lock(&cache->active_lock);
 111
 112         p = cache->active_nodes.rb_node;
 113         while (p) {
 114                 object = rb_entry(p, struct cachefiles_object, active_node);
 115                 if (object->dentry > dentry)
 116                         p = p->rb_left;
 117                 else if (object->dentry < dentry)
 118                         p = p->rb_right;
 119                 else
 120                         goto found_dentry;
 121         }
 122
 123         write_unlock(&cache->active_lock);
 124         _leave(" [no owner]");
 125         return;
 126
 127         /* found the dentry for  */
 128 found_dentry:
 129         kdebug("preemptive burial: OBJ%x [%s] %p",
 130                object->fscache.debug_id,
 131                fscache_object_states[object->fscache.state],
 132                dentry);
 133
 134         if (object->fscache.state < FSCACHE_OBJECT_DYING) {
 135                 printk(KERN_ERR "\n");
 136                 printk(KERN_ERR "CacheFiles: Error:"
 137                        " Can't preemptively bury live object\n");
 138                 cachefiles_printk_object(object, NULL);
 139         } else if (test_and_set_bit(CACHEFILES_OBJECT_BURIED, &object->flags)) {
 140                 printk(KERN_ERR "CacheFiles: Error:"
 141                        " Object already preemptively buried\n");
 142         }
 143
 144         write_unlock(&cache->active_lock);
 145         _leave(" [owner marked]");
 146 }
 147
 148 /*
 149  * record the fact that an object is now active
 150  */
 151 static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
 152                                          struct cachefiles_object *object)
 153 {
 154         struct cachefiles_object *xobject;
 155         struct rb_node **_p, *_parent = NULL;
 156         struct dentry *dentry;
 157
 158         _enter(",%p", object);
 159
 160 try_again:
 161         write_lock(&cache->active_lock);
 162
 163         if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
 164                 printk(KERN_ERR "CacheFiles: Error: Object already active\n");
 165                 cachefiles_printk_object(object, NULL);
 166                 BUG();
 167         }
 168
 169         dentry = object->dentry;
 170         _p = &cache->active_nodes.rb_node;
 171         while (*_p) {
 172                 _parent = *_p;
 173                 xobject = rb_entry(_parent,
 174                                    struct cachefiles_object, active_node);
 175
 176                 ASSERT(xobject != object);
 177
 178                 if (xobject->dentry > dentry)
 179                         _p = &(*_p)->rb_left;
 180                 else if (xobject->dentry < dentry)
 181                         _p = &(*_p)->rb_right;
 182                 else
 183                         goto wait_for_old_object;
 184         }
 185
 186         rb_link_node(&object->active_node, _parent, _p);
 187         rb_insert_color(&object->active_node, &cache->active_nodes);
 188
 189         write_unlock(&cache->active_lock);
 190         _leave(" = 0");
 191         return 0;
 192
 193         /* an old object from a previous incarnation is hogging the slot - we
 194          * need to wait for it to be destroyed */
 195 wait_for_old_object:
 196         if (xobject->fscache.state < FSCACHE_OBJECT_DYING) {
 197                 printk(KERN_ERR "\n");
 198                 printk(KERN_ERR "CacheFiles: Error:"
 199                        " Unexpected object collision\n");
 200                 cachefiles_printk_object(object, xobject);
 201                 BUG();
 202         }
 203         atomic_inc(&xobject->usage);
 204         write_unlock(&cache->active_lock);
 205
 206         if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 207                 wait_queue_head_t *wq;
 208
 209                 signed long timeout = 60 * HZ;
 210                 wait_queue_t wait;
 211                 bool requeue;
 212
 213                 /* if the object we're waiting for is queued for processing,
 214                  * then just put ourselves on the queue behind it */
 215                 if (work_pending(&xobject->fscache.work)) {
 216                         _debug("queue OBJ%x behind OBJ%x immediately",
 217                                object->fscache.debug_id,
 218                                xobject->fscache.debug_id);
 219                         goto requeue;
 220                 }
 221
 222                 /* otherwise we sleep until either the object we're waiting for
 223                  * is done, or the fscache_object is congested */
 224                 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
 225                 init_wait(&wait);
 226                 requeue = false;
 227                 do {
 228                         prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
 229                         if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
 230                                 break;
 231
 232                         requeue = fscache_object_sleep_till_congested(&timeout);
 233                 } while (timeout > 0 && !requeue);
 234                 finish_wait(wq, &wait);
 235
 236                 if (requeue &&
 237                     test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 238                         _debug("queue OBJ%x behind OBJ%x after wait",
 239                                object->fscache.debug_id,
 240                                xobject->fscache.debug_id);
 241                         goto requeue;
 242                 }
 243
 244                 if (timeout <= 0) {
 245                         printk(KERN_ERR "\n");
 246                         printk(KERN_ERR "CacheFiles: Error: Overlong"
 247                                " wait for old active object to go away\n");
 248                         cachefiles_printk_object(object, xobject);
 249                         goto requeue;
 250                 }
 251         }
 252
 253         ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
 254
 255         cache->cache.ops->put_object(&xobject->fscache);
 256         goto try_again;
 257
 258 requeue:
 259         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 260         cache->cache.ops->put_object(&xobject->fscache);
 261         _leave(" = -ETIMEDOUT");
 262         return -ETIMEDOUT;
 263 }
 264
 265 /*
 266  * delete an object representation from the cache
 267  * - file backed objects are unlinked
 268  * - directory backed objects are stuffed into the graveyard for userspace to
 269  *   delete
 270  * - unlocks the directory mutex
 271  */
 272 static int cachefiles_bury_object(struct cachefiles_cache *cache,
 273                                   struct dentry *dir,
 274                                   struct dentry *rep,
 275                                   bool preemptive)
 276 {
 277         struct dentry *grave, *trap;
 278         char nbuffer[8 + 8 + 1];
 279         int ret;
 280
 281         _enter(",'%*.*s','%*.*s'",
 282                dir->d_name.len, dir->d_name.len, dir->d_name.name,
 283                rep->d_name.len, rep->d_name.len, rep->d_name.name);
 284
 285         _debug("remove %p from %p", rep, dir);
 286
 287         /* non-directories can just be unlinked */
 288         if (!S_ISDIR(rep->d_inode->i_mode)) {
 289                 _debug("unlink stale object");
 290                 ret = vfs_unlink(dir->d_inode, rep);
 291
 292                 if (preemptive)
 293                         cachefiles_mark_object_buried(cache, rep);
 294
 295                 mutex_unlock(&dir->d_inode->i_mutex);
 296
 297                 if (ret == -EIO)
 298                         cachefiles_io_error(cache, "Unlink failed");
 299
 300                 _leave(" = %d", ret);
 301                 return ret;
 302         }
 303
 304         /* directories have to be moved to the graveyard */
 305         _debug("move stale object to graveyard");
 306         mutex_unlock(&dir->d_inode->i_mutex);
 307
 308 try_again:
 309         /* first step is to make up a grave dentry in the graveyard */
 310         sprintf(nbuffer, "%08x%08x",
 311                 (uint32_t) get_seconds(),
 312                 (uint32_t) atomic_inc_return(&cache->gravecounter));
 313
 314         /* do the multiway lock magic */
 315         trap = lock_rename(cache->graveyard, dir);
 316
 317         /* do some checks before getting the grave dentry */
 318         if (rep->d_parent != dir) {
 319                 /* the entry was probably culled when we dropped the parent dir
 320                  * lock */
 321                 unlock_rename(cache->graveyard, dir);
 322                 _leave(" = 0 [culled?]");
 323                 return 0;
 324         }
 325
 326         if (!S_ISDIR(cache->graveyard->d_inode->i_mode)) {
 327                 unlock_rename(cache->graveyard, dir);
 328                 cachefiles_io_error(cache, "Graveyard no longer a directory");
 329                 return -EIO;
 330         }
 331
 332         if (trap == rep) {
 333                 unlock_rename(cache->graveyard, dir);
 334                 cachefiles_io_error(cache, "May not make directory loop");
 335                 return -EIO;
 336         }
 337
 338         if (d_mountpoint(rep)) {
 339                 unlock_rename(cache->graveyard, dir);
 340                 cachefiles_io_error(cache, "Mountpoint in cache");
 341                 return -EIO;
 342         }
 343
 344         grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
 345         if (IS_ERR(grave)) {
 346                 unlock_rename(cache->graveyard, dir);
 347
 348                 if (PTR_ERR(grave) == -ENOMEM) {
 349                         _leave(" = -ENOMEM");
 350                         return -ENOMEM;
 351                 }
 352
 353                 cachefiles_io_error(cache, "Lookup error %ld",
 354                                     PTR_ERR(grave));
 355                 return -EIO;
 356         }
 357
 358         if (grave->d_inode) {
 359                 unlock_rename(cache->graveyard, dir);
 360                 dput(grave);
 361                 grave = NULL;
 362                 cond_resched();
 363                 goto try_again;
 364         }
 365
 366         if (d_mountpoint(grave)) {
 367                 unlock_rename(cache->graveyard, dir);
 368                 dput(grave);
 369                 cachefiles_io_error(cache, "Mountpoint in graveyard");
 370                 return -EIO;
 371         }
 372
 373         /* target should not be an ancestor of source */
 374         if (trap == grave) {
 375                 unlock_rename(cache->graveyard, dir);
 376                 dput(grave);
 377                 cachefiles_io_error(cache, "May not make directory loop");
 378                 return -EIO;
 379         }
 380
 381         /* attempt the rename */
 382         ret = vfs_rename(dir->d_inode, rep, cache->graveyard->d_inode, grave);
 383         if (ret != 0 && ret != -ENOMEM)
 384                 cachefiles_io_error(cache, "Rename failed with error %d", ret);
 385
 386         if (preemptive)
 387                 cachefiles_mark_object_buried(cache, rep);
 388
 389         unlock_rename(cache->graveyard, dir);
 390         dput(grave);
 391         _leave(" = 0");
 392         return 0;
 393 }
 394
 395 /*
 396  * delete an object representation from the cache
 397  */
 398 int cachefiles_delete_object(struct cachefiles_cache *cache,
 399                              struct cachefiles_object *object)
 400 {
 401         struct dentry *dir;
 402         int ret;
 403
 404         _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
 405
 406         ASSERT(object->dentry);
 407         ASSERT(object->dentry->d_inode);
 408         ASSERT(object->dentry->d_parent);
 409
 410         dir = dget_parent(object->dentry);
 411
 412         mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 413
 414         if (test_bit(CACHEFILES_OBJECT_BURIED, &object->flags)) {
 415                 /* object allocation for the same key preemptively deleted this
 416                  * object's file so that it could create its own file */
 417                 _debug("object preemptively buried");
 418                 mutex_unlock(&dir->d_inode->i_mutex);
 419                 ret = 0;
 420         } else {
 421                 /* we need to check that our parent is _still_ our parent - it
 422                  * may have been renamed */
 423                 if (dir == object->dentry->d_parent) {
 424                         ret = cachefiles_bury_object(cache, dir,
 425                                                      object->dentry, false);
 426                 } else {
 427                         /* it got moved, presumably by cachefilesd culling it,
 428                          * so it's no longer in the key path and we can ignore
 429                          * it */
 430                         mutex_unlock(&dir->d_inode->i_mutex);
 431                         ret = 0;
 432                 }
 433         }
 434
 435         dput(dir);
 436         _leave(" = %d", ret);
 437         return ret;
 438 }
 439
 440 /*
 441  * walk from the parent object to the child object through the backing
 442  * filesystem, creating directories as we go
 443  */
 444 int cachefiles_walk_to_object(struct cachefiles_object *parent,
 445                               struct cachefiles_object *object,
 446                               const char *key,
 447                               struct cachefiles_xattr *auxdata)
 448 {
 449         struct cachefiles_cache *cache;
 450         struct dentry *dir, *next = NULL;
 451         unsigned long start;
 452         const char *name;
 453         int ret, nlen;
 454
 455         _enter("OBJ%x{%p},OBJ%x,%s,",
 456                parent->fscache.debug_id, parent->dentry,
 457                object->fscache.debug_id, key);
 458
 459         cache = container_of(parent->fscache.cache,
 460                              struct cachefiles_cache, cache);
 461
 462         ASSERT(parent->dentry);
 463         ASSERT(parent->dentry->d_inode);
 464
 465         if (!(S_ISDIR(parent->dentry->d_inode->i_mode))) {
 466                 // TODO: convert file to dir
 467                 _leave("looking up in none directory");
 468                 return -ENOBUFS;
 469         }
 470
 471         dir = dget(parent->dentry);
 472
 473 advance:
 474         /* attempt to transit the first directory component */
 475         name = key;
 476         nlen = strlen(key);
 477
 478         /* key ends in a double NUL */
 479         key = key + nlen + 1;
 480         if (!*key)
 481                 key = NULL;
 482
 483 lookup_again:
 484         /* search the current directory for the element name */
 485         _debug("lookup '%s'", name);
 486
 487         mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 488
 489         start = jiffies;
 490         next = lookup_one_len(name, dir, nlen);
 491         cachefiles_hist(cachefiles_lookup_histogram, start);
 492         if (IS_ERR(next))
 493                 goto lookup_error;
 494
 495         _debug("next -> %p %s", next, next->d_inode ? "positive" : "negative");
 496
 497         if (!key)
 498                 object->new = !next->d_inode;
 499
 500         /* if this element of the path doesn't exist, then the lookup phase
 501          * failed, and we can release any readers in the certain knowledge that
 502          * there's nothing for them to actually read */
 503         if (!next->d_inode)
 504                 fscache_object_lookup_negative(&object->fscache);
 505
 506         /* we need to create the object if it's negative */
 507         if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
 508                 /* index objects and intervening tree levels must be subdirs */
 509                 if (!next->d_inode) {
 510                         ret = cachefiles_has_space(cache, 1, 0);
 511                         if (ret < 0)
 512                                 goto create_error;
 513
 514                         start = jiffies;
 515                         ret = vfs_mkdir(dir->d_inode, next, 0);
 516                         cachefiles_hist(cachefiles_mkdir_histogram, start);
 517                         if (ret < 0)
 518                                 goto create_error;
 519
 520                         ASSERT(next->d_inode);
 521
 522                         _debug("mkdir -> %p{%p{ino=%lu}}",
 523                                next, next->d_inode, next->d_inode->i_ino);
 524
 525                 } else if (!S_ISDIR(next->d_inode->i_mode)) {
 526                         kerror("inode %lu is not a directory",
 527                                next->d_inode->i_ino);
 528                         ret = -ENOBUFS;
 529                         goto error;
 530                 }
 531
 532         } else {
 533                 /* non-index objects start out life as files */
 534                 if (!next->d_inode) {
 535                         ret = cachefiles_has_space(cache, 1, 0);
 536                         if (ret < 0)
 537                                 goto create_error;
 538
 539                         start = jiffies;
 540                         ret = vfs_create(dir->d_inode, next, S_IFREG, NULL);
 541                         cachefiles_hist(cachefiles_create_histogram, start);
 542                         if (ret < 0)
 543                                 goto create_error;
 544
 545                         ASSERT(next->d_inode);
 546
 547                         _debug("create -> %p{%p{ino=%lu}}",
 548                                next, next->d_inode, next->d_inode->i_ino);
 549
 550                 } else if (!S_ISDIR(next->d_inode->i_mode) &&
 551                            !S_ISREG(next->d_inode->i_mode)
 552                            ) {
 553                         kerror("inode %lu is not a file or directory",
 554                                next->d_inode->i_ino);
 555                         ret = -ENOBUFS;
 556                         goto error;
 557                 }
 558         }
 559
 560         /* process the next component */
 561         if (key) {
 562                 _debug("advance");
 563                 mutex_unlock(&dir->d_inode->i_mutex);
 564                 dput(dir);
 565                 dir = next;
 566                 next = NULL;
 567                 goto advance;
 568         }
 569
 570         /* we've found the object we were looking for */
 571         object->dentry = next;
 572
 573         /* if we've found that the terminal object exists, then we need to
 574          * check its attributes and delete it if it's out of date */
 575         if (!object->new) {
 576                 _debug("validate '%*.*s'",
 577                        next->d_name.len, next->d_name.len, next->d_name.name);
 578
 579                 ret = cachefiles_check_object_xattr(object, auxdata);
 580                 if (ret == -ESTALE) {
 581                         /* delete the object (the deleter drops the directory
 582                          * mutex) */
 583                         object->dentry = NULL;
 584
 585                         ret = cachefiles_bury_object(cache, dir, next, true);
 586                         dput(next);
 587                         next = NULL;
 588
 589                         if (ret < 0)
 590                                 goto delete_error;
 591
 592                         _debug("redo lookup");
 593                         goto lookup_again;
 594                 }
 595         }
 596
 597         /* note that we're now using this object */
 598         ret = cachefiles_mark_object_active(cache, object);
 599
 600         mutex_unlock(&dir->d_inode->i_mutex);
 601         dput(dir);
 602         dir = NULL;
 603
 604         if (ret == -ETIMEDOUT)
 605                 goto mark_active_timed_out;
 606
 607         _debug("=== OBTAINED_OBJECT ===");
 608
 609         if (object->new) {
 610                 /* attach data to a newly constructed terminal object */
 611                 ret = cachefiles_set_object_xattr(object, auxdata);
 612                 if (ret < 0)
 613                         goto check_error;
 614         } else {
 615                 /* always update the atime on an object we've just looked up
 616                  * (this is used to keep track of culling, and atimes are only
 617                  * updated by read, write and readdir but not lookup or
 618                  * open) */
 619                 touch_atime(cache->mnt, next);
 620         }
 621
 622         /* open a file interface onto a data file */
 623         if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
 624                 if (S_ISREG(object->dentry->d_inode->i_mode)) {
 625                         const struct address_space_operations *aops;
 626
 627                         ret = -EPERM;
 628                         aops = object->dentry->d_inode->i_mapping->a_ops;
 629                         if (!aops->bmap)
 630                                 goto check_error;
 631
 632                         object->backer = object->dentry;
 633                 } else {
 634                         BUG(); // TODO: open file in data-class subdir
 635                 }
 636         }
 637
 638         object->new = 0;
 639         fscache_obtained_object(&object->fscache);
 640
 641         _leave(" = 0 [%lu]", object->dentry->d_inode->i_ino);
 642         return 0;
 643
 644 create_error:
 645         _debug("create error %d", ret);
 646         if (ret == -EIO)
 647                 cachefiles_io_error(cache, "Create/mkdir failed");
 648         goto error;
 649
 650 mark_active_timed_out:
 651         _debug("mark active timed out");
 652         goto release_dentry;
 653
 654 check_error:
 655         _debug("check error %d", ret);
 656         write_lock(&cache->active_lock);
 657         rb_erase(&object->active_node, &cache->active_nodes);
 658         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 659         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
 660         write_unlock(&cache->active_lock);
 661 release_dentry:
 662         dput(object->dentry);
 663         object->dentry = NULL;
 664         goto error_out;
 665
 666 delete_error:
 667         _debug("delete error %d", ret);
 668         goto error_out2;
 669
 670 lookup_error:
 671         _debug("lookup error %ld", PTR_ERR(next));
 672         ret = PTR_ERR(next);
 673         if (ret == -EIO)
 674                 cachefiles_io_error(cache, "Lookup failed");
 675         next = NULL;
 676 error:
 677         mutex_unlock(&dir->d_inode->i_mutex);
 678         dput(next);
 679 error_out2:
 680         dput(dir);
 681 error_out:
 682         _leave(" = error %d", -ret);
 683         return ret;
 684 }
 685
 686 /*
 687  * get a subdirectory
 688  */
 689 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
 690                                         struct dentry *dir,
 691                                         const char *dirname)
 692 {
 693         struct dentry *subdir;
 694         unsigned long start;
 695         int ret;
 696
 697         _enter(",,%s", dirname);
 698
 699         /* search the current directory for the element name */
 700         mutex_lock(&dir->d_inode->i_mutex);
 701
 702         start = jiffies;
 703         subdir = lookup_one_len(dirname, dir, strlen(dirname));
 704         cachefiles_hist(cachefiles_lookup_histogram, start);
 705         if (IS_ERR(subdir)) {
 706                 if (PTR_ERR(subdir) == -ENOMEM)
 707                         goto nomem_d_alloc;
 708                 goto lookup_error;
 709         }
 710
 711         _debug("subdir -> %p %s",
 712                subdir, subdir->d_inode ? "positive" : "negative");
 713
 714         /* we need to create the subdir if it doesn't exist yet */
 715         if (!subdir->d_inode) {
 716                 ret = cachefiles_has_space(cache, 1, 0);
 717                 if (ret < 0)
 718                         goto mkdir_error;
 719
 720                 _debug("attempt mkdir");
 721
 722                 ret = vfs_mkdir(dir->d_inode, subdir, 0700);
 723                 if (ret < 0)
 724                         goto mkdir_error;
 725
 726                 ASSERT(subdir->d_inode);
 727
 728                 _debug("mkdir -> %p{%p{ino=%lu}}",
 729                        subdir,
 730                        subdir->d_inode,
 731                        subdir->d_inode->i_ino);
 732         }
 733
 734         mutex_unlock(&dir->d_inode->i_mutex);
 735
 736         /* we need to make sure the subdir is a directory */
 737         ASSERT(subdir->d_inode);
 738
 739         if (!S_ISDIR(subdir->d_inode->i_mode)) {
 740                 kerror("%s is not a directory", dirname);
 741                 ret = -EIO;
 742                 goto check_error;
 743         }
 744
 745         ret = -EPERM;
 746         if (!subdir->d_inode->i_op ||
 747             !subdir->d_inode->i_op->setxattr ||
 748             !subdir->d_inode->i_op->getxattr ||
 749             !subdir->d_inode->i_op->lookup ||
 750             !subdir->d_inode->i_op->mkdir ||
 751             !subdir->d_inode->i_op->create ||
 752             !subdir->d_inode->i_op->rename ||
 753             !subdir->d_inode->i_op->rmdir ||
 754             !subdir->d_inode->i_op->unlink)
 755                 goto check_error;
 756
 757         _leave(" = [%lu]", subdir->d_inode->i_ino);
 758         return subdir;
 759
 760 check_error:
 761         dput(subdir);
 762         _leave(" = %d [check]", ret);
 763         return ERR_PTR(ret);
 764
 765 mkdir_error:
 766         mutex_unlock(&dir->d_inode->i_mutex);
 767         dput(subdir);
 768         kerror("mkdir %s failed with error %d", dirname, ret);
 769         return ERR_PTR(ret);
 770
 771 lookup_error:
 772         mutex_unlock(&dir->d_inode->i_mutex);
 773         ret = PTR_ERR(subdir);
 774         kerror("Lookup %s failed with error %d", dirname, ret);
 775         return ERR_PTR(ret);
 776
 777 nomem_d_alloc:
 778         mutex_unlock(&dir->d_inode->i_mutex);
 779         _leave(" = -ENOMEM");
 780         return ERR_PTR(-ENOMEM);
 781 }
 782
 783 /*
 784  * find out if an object is in use or not
 785  * - if finds object and it's not in use:
 786  *   - returns a pointer to the object and a reference on it
 787  *   - returns with the directory locked
 788  */
 789 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
 790                                               struct dentry *dir,
 791                                               char *filename)
 792 {
 793         struct cachefiles_object *object;
 794         struct rb_node *_n;
 795         struct dentry *victim;
 796         unsigned long start;
 797         int ret;
 798
 799         //_enter(",%*.*s/,%s",
 800         //       dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 801
 802         /* look up the victim */
 803         mutex_lock_nested(&dir->d_inode->i_mutex, 1);
 804
 805         start = jiffies;
 806         victim = lookup_one_len(filename, dir, strlen(filename));
 807         cachefiles_hist(cachefiles_lookup_histogram, start);
 808         if (IS_ERR(victim))
 809                 goto lookup_error;
 810
 811         //_debug("victim -> %p %s",
 812         //       victim, victim->d_inode ? "positive" : "negative");
 813
 814         /* if the object is no longer there then we probably retired the object
 815          * at the netfs's request whilst the cull was in progress
 816          */
 817         if (!victim->d_inode) {
 818                 mutex_unlock(&dir->d_inode->i_mutex);
 819                 dput(victim);
 820                 _leave(" = -ENOENT [absent]");
 821                 return ERR_PTR(-ENOENT);
 822         }
 823
 824         /* check to see if we're using this object */
 825         read_lock(&cache->active_lock);
 826
 827         _n = cache->active_nodes.rb_node;
 828
 829         while (_n) {
 830                 object = rb_entry(_n, struct cachefiles_object, active_node);
 831
 832                 if (object->dentry > victim)
 833                         _n = _n->rb_left;
 834                 else if (object->dentry < victim)
 835                         _n = _n->rb_right;
 836                 else
 837                         goto object_in_use;
 838         }
 839
 840         read_unlock(&cache->active_lock);
 841
 842         //_leave(" = %p", victim);
 843         return victim;
 844
 845 object_in_use:
 846         read_unlock(&cache->active_lock);
 847         mutex_unlock(&dir->d_inode->i_mutex);
 848         dput(victim);
 849         //_leave(" = -EBUSY [in use]");
 850         return ERR_PTR(-EBUSY);
 851
 852 lookup_error:
 853         mutex_unlock(&dir->d_inode->i_mutex);
 854         ret = PTR_ERR(victim);
 855         if (ret == -ENOENT) {
 856                 /* file or dir now absent - probably retired by netfs */
 857                 _leave(" = -ESTALE [absent]");
 858                 return ERR_PTR(-ESTALE);
 859         }
 860
 861         if (ret == -EIO) {
 862                 cachefiles_io_error(cache, "Lookup failed");
 863         } else if (ret != -ENOMEM) {
 864                 kerror("Internal error: %d", ret);
 865                 ret = -EIO;
 866         }
 867
 868         _leave(" = %d", ret);
 869         return ERR_PTR(ret);
 870 }
 871
 872 /*
 873  * cull an object if it's not in use
 874  * - called only by cache manager daemon
 875  */
 876 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
 877                     char *filename)
 878 {
 879         struct dentry *victim;
 880         int ret;
 881
 882         _enter(",%*.*s/,%s",
 883                dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 884
 885         victim = cachefiles_check_active(cache, dir, filename);
 886         if (IS_ERR(victim))
 887                 return PTR_ERR(victim);
 888
 889         _debug("victim -> %p %s",
 890                victim, victim->d_inode ? "positive" : "negative");
 891
 892         /* okay... the victim is not being used so we can cull it
 893          * - start by marking it as stale
 894          */
 895         _debug("victim is cullable");
 896
 897         ret = cachefiles_remove_object_xattr(cache, victim);
 898         if (ret < 0)
 899                 goto error_unlock;
 900
 901         /*  actually remove the victim (drops the dir mutex) */
 902         _debug("bury");
 903
 904         ret = cachefiles_bury_object(cache, dir, victim, false);
 905         if (ret < 0)
 906                 goto error;
 907
 908         dput(victim);
 909         _leave(" = 0");
 910         return 0;
 911
 912 error_unlock:
 913         mutex_unlock(&dir->d_inode->i_mutex);
 914 error:
 915         dput(victim);
 916         if (ret == -ENOENT) {
 917                 /* file or dir now absent - probably retired by netfs */
 918                 _leave(" = -ESTALE [absent]");
 919                 return -ESTALE;
 920         }
 921
 922         if (ret != -ENOMEM) {
 923                 kerror("Internal error: %d", ret);
 924                 ret = -EIO;
 925         }
 926
 927         _leave(" = %d", ret);
 928         return ret;
 929 }
 930
 931 /*
 932  * find out if an object is in use or not
 933  * - called only by cache manager daemon
 934  * - returns -EBUSY or 0 to indicate whether an object is in use or not
 935  */
 936 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
 937                             char *filename)
 938 {
 939         struct dentry *victim;
 940
 941         //_enter(",%*.*s/,%s",
 942         //       dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 943
 944         victim = cachefiles_check_active(cache, dir, filename);
 945         if (IS_ERR(victim))
 946                 return PTR_ERR(victim);
 947
 948         mutex_unlock(&dir->d_inode->i_mutex);
 949         dput(victim);
 950         //_leave(" = 0");
 951         return 0;
 952 }