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 swfl=%lx ev=%lx[%lx]\n",
  41                prefix, fscache_object_states[object->fscache.state],
  42                object->fscache.flags, object->fscache.work.flags,
  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 (slow_work_is_queued(&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 slow-work facility wants the thread back to
 224                  * do other work */
 225                 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
 226                 init_wait(&wait);
 227                 requeue = false;
 228                 do {
 229                         prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
 230                         if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
 231                                 break;
 232                         requeue = slow_work_sleep_till_thread_needed(
 233                                 &object->fscache.work, &timeout);
 234                 } while (timeout > 0 && !requeue);
 235                 finish_wait(wq, &wait);
 236
 237                 if (requeue &&
 238                     test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 239                         _debug("queue OBJ%x behind OBJ%x after wait",
 240                                object->fscache.debug_id,
 241                                xobject->fscache.debug_id);
 242                         goto requeue;
 243                 }
 244
 245                 if (timeout <= 0) {
 246                         printk(KERN_ERR "\n");
 247                         printk(KERN_ERR "CacheFiles: Error: Overlong"
 248                                " wait for old active object to go away\n");
 249                         cachefiles_printk_object(object, xobject);
 250                         goto requeue;
 251                 }
 252         }
 253
 254         ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
 255
 256         cache->cache.ops->put_object(&xobject->fscache);
 257         goto try_again;
 258
 259 requeue:
 260         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 261         cache->cache.ops->put_object(&xobject->fscache);
 262         _leave(" = -ETIMEDOUT");
 263         return -ETIMEDOUT;
 264 }
 265
 266 /*
 267  * delete an object representation from the cache
 268  * - file backed objects are unlinked
 269  * - directory backed objects are stuffed into the graveyard for userspace to
 270  *   delete
 271  * - unlocks the directory mutex
 272  */
 273 static int cachefiles_bury_object(struct cachefiles_cache *cache,
 274                                   struct dentry *dir,
 275                                   struct dentry *rep,
 276                                   bool preemptive)
 277 {
 278         struct dentry *grave, *trap;
 279         char nbuffer[8 + 8 + 1];
 280         int ret;
 281
 282         _enter(",'%*.*s','%*.*s'",
 283                dir->d_name.len, dir->d_name.len, dir->d_name.name,
 284                rep->d_name.len, rep->d_name.len, rep->d_name.name);
 285
 286         _debug("remove %p from %p", rep, dir);
 287
 288         /* non-directories can just be unlinked */
 289         if (!S_ISDIR(rep->d_inode->i_mode)) {
 290                 _debug("unlink stale object");
 291                 ret = vfs_unlink(dir->d_inode, rep);
 292
 293                 if (preemptive)
 294                         cachefiles_mark_object_buried(cache, rep);
 295
 296                 mutex_unlock(&dir->d_inode->i_mutex);
 297
 298                 if (ret == -EIO)
 299                         cachefiles_io_error(cache, "Unlink failed");
 300
 301                 _leave(" = %d", ret);
 302                 return ret;
 303         }
 304
 305         /* directories have to be moved to the graveyard */
 306         _debug("move stale object to graveyard");
 307         mutex_unlock(&dir->d_inode->i_mutex);
 308
 309 try_again:
 310         /* first step is to make up a grave dentry in the graveyard */
 311         sprintf(nbuffer, "%08x%08x",
 312                 (uint32_t) get_seconds(),
 313                 (uint32_t) atomic_inc_return(&cache->gravecounter));
 314
 315         /* do the multiway lock magic */
 316         trap = lock_rename(cache->graveyard, dir);
 317
 318         /* do some checks before getting the grave dentry */
 319         if (rep->d_parent != dir) {
 320                 /* the entry was probably culled when we dropped the parent dir
 321                  * lock */
 322                 unlock_rename(cache->graveyard, dir);
 323                 _leave(" = 0 [culled?]");
 324                 return 0;
 325         }
 326
 327         if (!S_ISDIR(cache->graveyard->d_inode->i_mode)) {
 328                 unlock_rename(cache->graveyard, dir);
 329                 cachefiles_io_error(cache, "Graveyard no longer a directory");
 330                 return -EIO;
 331         }
 332
 333         if (trap == rep) {
 334                 unlock_rename(cache->graveyard, dir);
 335                 cachefiles_io_error(cache, "May not make directory loop");
 336                 return -EIO;
 337         }
 338
 339         if (d_mountpoint(rep)) {
 340                 unlock_rename(cache->graveyard, dir);
 341                 cachefiles_io_error(cache, "Mountpoint in cache");
 342                 return -EIO;
 343         }
 344
 345         grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
 346         if (IS_ERR(grave)) {
 347                 unlock_rename(cache->graveyard, dir);
 348
 349                 if (PTR_ERR(grave) == -ENOMEM) {
 350                         _leave(" = -ENOMEM");
 351                         return -ENOMEM;
 352                 }
 353
 354                 cachefiles_io_error(cache, "Lookup error %ld",
 355                                     PTR_ERR(grave));
 356                 return -EIO;
 357         }
 358
 359         if (grave->d_inode) {
 360                 unlock_rename(cache->graveyard, dir);
 361                 dput(grave);
 362                 grave = NULL;
 363                 cond_resched();
 364                 goto try_again;
 365         }
 366
 367         if (d_mountpoint(grave)) {
 368                 unlock_rename(cache->graveyard, dir);
 369                 dput(grave);
 370                 cachefiles_io_error(cache, "Mountpoint in graveyard");
 371                 return -EIO;
 372         }
 373
 374         /* target should not be an ancestor of source */
 375         if (trap == grave) {
 376                 unlock_rename(cache->graveyard, dir);
 377                 dput(grave);
 378                 cachefiles_io_error(cache, "May not make directory loop");
 379                 return -EIO;
 380         }
 381
 382         /* attempt the rename */
 383         ret = vfs_rename(dir->d_inode, rep, cache->graveyard->d_inode, grave);
 384         if (ret != 0 && ret != -ENOMEM)
 385                 cachefiles_io_error(cache, "Rename failed with error %d", ret);
 386
 387         if (preemptive)
 388                 cachefiles_mark_object_buried(cache, rep);
 389
 390         unlock_rename(cache->graveyard, dir);
 391         dput(grave);
 392         _leave(" = 0");
 393         return 0;
 394 }
 395
 396 /*
 397  * delete an object representation from the cache
 398  */
 399 int cachefiles_delete_object(struct cachefiles_cache *cache,
 400                              struct cachefiles_object *object)
 401 {
 402         struct dentry *dir;
 403         int ret;
 404
 405         _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
 406
 407         ASSERT(object->dentry);
 408         ASSERT(object->dentry->d_inode);
 409         ASSERT(object->dentry->d_parent);
 410
 411         dir = dget_parent(object->dentry);
 412
 413         mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 414
 415         if (test_bit(CACHEFILES_OBJECT_BURIED, &object->flags)) {
 416                 /* object allocation for the same key preemptively deleted this
 417                  * object's file so that it could create its own file */
 418                 _debug("object preemptively buried");
 419                 mutex_unlock(&dir->d_inode->i_mutex);
 420                 ret = 0;
 421         } else {
 422                 /* we need to check that our parent is _still_ our parent - it
 423                  * may have been renamed */
 424                 if (dir == object->dentry->d_parent) {
 425                         ret = cachefiles_bury_object(cache, dir,
 426                                                      object->dentry, false);
 427                 } else {
 428                         /* it got moved, presumably by cachefilesd culling it,
 429                          * so it's no longer in the key path and we can ignore
 430                          * it */
 431                         mutex_unlock(&dir->d_inode->i_mutex);
 432                         ret = 0;
 433                 }
 434         }
 435
 436         dput(dir);
 437         _leave(" = %d", ret);
 438         return ret;
 439 }
 440
 441 /*
 442  * walk from the parent object to the child object through the backing
 443  * filesystem, creating directories as we go
 444  */
 445 int cachefiles_walk_to_object(struct cachefiles_object *parent,
 446                               struct cachefiles_object *object,
 447                               const char *key,
 448                               struct cachefiles_xattr *auxdata)
 449 {
 450         struct cachefiles_cache *cache;
 451         struct dentry *dir, *next = NULL;
 452         unsigned long start;
 453         const char *name;
 454         int ret, nlen;
 455
 456         _enter("OBJ%x{%p},OBJ%x,%s,",
 457                parent->fscache.debug_id, parent->dentry,
 458                object->fscache.debug_id, key);
 459
 460         cache = container_of(parent->fscache.cache,
 461                              struct cachefiles_cache, cache);
 462
 463         ASSERT(parent->dentry);
 464         ASSERT(parent->dentry->d_inode);
 465
 466         if (!(S_ISDIR(parent->dentry->d_inode->i_mode))) {
 467                 // TODO: convert file to dir
 468                 _leave("looking up in none directory");
 469                 return -ENOBUFS;
 470         }
 471
 472         dir = dget(parent->dentry);
 473
 474 advance:
 475         /* attempt to transit the first directory component */
 476         name = key;
 477         nlen = strlen(key);
 478
 479         /* key ends in a double NUL */
 480         key = key + nlen + 1;
 481         if (!*key)
 482                 key = NULL;
 483
 484 lookup_again:
 485         /* search the current directory for the element name */
 486         _debug("lookup '%s'", name);
 487
 488         mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 489
 490         start = jiffies;
 491         next = lookup_one_len(name, dir, nlen);
 492         cachefiles_hist(cachefiles_lookup_histogram, start);
 493         if (IS_ERR(next))
 494                 goto lookup_error;
 495
 496         _debug("next -> %p %s", next, next->d_inode ? "positive" : "negative");
 497
 498         if (!key)
 499                 object->new = !next->d_inode;
 500
 501         /* if this element of the path doesn't exist, then the lookup phase
 502          * failed, and we can release any readers in the certain knowledge that
 503          * there's nothing for them to actually read */
 504         if (!next->d_inode)
 505                 fscache_object_lookup_negative(&object->fscache);
 506
 507         /* we need to create the object if it's negative */
 508         if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
 509                 /* index objects and intervening tree levels must be subdirs */
 510                 if (!next->d_inode) {
 511                         ret = cachefiles_has_space(cache, 1, 0);
 512                         if (ret < 0)
 513                                 goto create_error;
 514
 515                         start = jiffies;
 516                         ret = vfs_mkdir(dir->d_inode, next, 0);
 517                         cachefiles_hist(cachefiles_mkdir_histogram, start);
 518                         if (ret < 0)
 519                                 goto create_error;
 520
 521                         ASSERT(next->d_inode);
 522
 523                         _debug("mkdir -> %p{%p{ino=%lu}}",
 524                                next, next->d_inode, next->d_inode->i_ino);
 525
 526                 } else if (!S_ISDIR(next->d_inode->i_mode)) {
 527                         kerror("inode %lu is not a directory",
 528                                next->d_inode->i_ino);
 529                         ret = -ENOBUFS;
 530                         goto error;
 531                 }
 532
 533         } else {
 534                 /* non-index objects start out life as files */
 535                 if (!next->d_inode) {
 536                         ret = cachefiles_has_space(cache, 1, 0);
 537                         if (ret < 0)
 538                                 goto create_error;
 539
 540                         start = jiffies;
 541                         ret = vfs_create(dir->d_inode, next, S_IFREG, NULL);
 542                         cachefiles_hist(cachefiles_create_histogram, start);
 543                         if (ret < 0)
 544                                 goto create_error;
 545
 546                         ASSERT(next->d_inode);
 547
 548                         _debug("create -> %p{%p{ino=%lu}}",
 549                                next, next->d_inode, next->d_inode->i_ino);
 550
 551                 } else if (!S_ISDIR(next->d_inode->i_mode) &&
 552                            !S_ISREG(next->d_inode->i_mode)
 553                            ) {
 554                         kerror("inode %lu is not a file or directory",
 555                                next->d_inode->i_ino);
 556                         ret = -ENOBUFS;
 557                         goto error;
 558                 }
 559         }
 560
 561         /* process the next component */
 562         if (key) {
 563                 _debug("advance");
 564                 mutex_unlock(&dir->d_inode->i_mutex);
 565                 dput(dir);
 566                 dir = next;
 567                 next = NULL;
 568                 goto advance;
 569         }
 570
 571         /* we've found the object we were looking for */
 572         object->dentry = next;
 573
 574         /* if we've found that the terminal object exists, then we need to
 575          * check its attributes and delete it if it's out of date */
 576         if (!object->new) {
 577                 _debug("validate '%*.*s'",
 578                        next->d_name.len, next->d_name.len, next->d_name.name);
 579
 580                 ret = cachefiles_check_object_xattr(object, auxdata);
 581                 if (ret == -ESTALE) {
 582                         /* delete the object (the deleter drops the directory
 583                          * mutex) */
 584                         object->dentry = NULL;
 585
 586                         ret = cachefiles_bury_object(cache, dir, next, true);
 587                         dput(next);
 588                         next = NULL;
 589
 590                         if (ret < 0)
 591                                 goto delete_error;
 592
 593                         _debug("redo lookup");
 594                         goto lookup_again;
 595                 }
 596         }
 597
 598         /* note that we're now using this object */
 599         ret = cachefiles_mark_object_active(cache, object);
 600
 601         mutex_unlock(&dir->d_inode->i_mutex);
 602         dput(dir);
 603         dir = NULL;
 604
 605         if (ret == -ETIMEDOUT)
 606                 goto mark_active_timed_out;
 607
 608         _debug("=== OBTAINED_OBJECT ===");
 609
 610         if (object->new) {
 611                 /* attach data to a newly constructed terminal object */
 612                 ret = cachefiles_set_object_xattr(object, auxdata);
 613                 if (ret < 0)
 614                         goto check_error;
 615         } else {
 616                 /* always update the atime on an object we've just looked up
 617                  * (this is used to keep track of culling, and atimes are only
 618                  * updated by read, write and readdir but not lookup or
 619                  * open) */
 620                 touch_atime(cache->mnt, next);
 621         }
 622
 623         /* open a file interface onto a data file */
 624         if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
 625                 if (S_ISREG(object->dentry->d_inode->i_mode)) {
 626                         const struct address_space_operations *aops;
 627
 628                         ret = -EPERM;
 629                         aops = object->dentry->d_inode->i_mapping->a_ops;
 630                         if (!aops->bmap)
 631                                 goto check_error;
 632
 633                         object->backer = object->dentry;
 634                 } else {
 635                         BUG(); // TODO: open file in data-class subdir
 636                 }
 637         }
 638
 639         object->new = 0;
 640         fscache_obtained_object(&object->fscache);
 641
 642         _leave(" = 0 [%lu]", object->dentry->d_inode->i_ino);
 643         return 0;
 644
 645 create_error:
 646         _debug("create error %d", ret);
 647         if (ret == -EIO)
 648                 cachefiles_io_error(cache, "Create/mkdir failed");
 649         goto error;
 650
 651 mark_active_timed_out:
 652         _debug("mark active timed out");
 653         goto release_dentry;
 654
 655 check_error:
 656         _debug("check error %d", ret);
 657         write_lock(&cache->active_lock);
 658         rb_erase(&object->active_node, &cache->active_nodes);
 659         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 660         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
 661         write_unlock(&cache->active_lock);
 662 release_dentry:
 663         dput(object->dentry);
 664         object->dentry = NULL;
 665         goto error_out;
 666
 667 delete_error:
 668         _debug("delete error %d", ret);
 669         goto error_out2;
 670
 671 lookup_error:
 672         _debug("lookup error %ld", PTR_ERR(next));
 673         ret = PTR_ERR(next);
 674         if (ret == -EIO)
 675                 cachefiles_io_error(cache, "Lookup failed");
 676         next = NULL;
 677 error:
 678         mutex_unlock(&dir->d_inode->i_mutex);
 679         dput(next);
 680 error_out2:
 681         dput(dir);
 682 error_out:
 683         _leave(" = error %d", -ret);
 684         return ret;
 685 }
 686
 687 /*
 688  * get a subdirectory
 689  */
 690 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
 691                                         struct dentry *dir,
 692                                         const char *dirname)
 693 {
 694         struct dentry *subdir;
 695         unsigned long start;
 696         int ret;
 697
 698         _enter(",,%s", dirname);
 699
 700         /* search the current directory for the element name */
 701         mutex_lock(&dir->d_inode->i_mutex);
 702
 703         start = jiffies;
 704         subdir = lookup_one_len(dirname, dir, strlen(dirname));
 705         cachefiles_hist(cachefiles_lookup_histogram, start);
 706         if (IS_ERR(subdir)) {
 707                 if (PTR_ERR(subdir) == -ENOMEM)
 708                         goto nomem_d_alloc;
 709                 goto lookup_error;
 710         }
 711
 712         _debug("subdir -> %p %s",
 713                subdir, subdir->d_inode ? "positive" : "negative");
 714
 715         /* we need to create the subdir if it doesn't exist yet */
 716         if (!subdir->d_inode) {
 717                 ret = cachefiles_has_space(cache, 1, 0);
 718                 if (ret < 0)
 719                         goto mkdir_error;
 720
 721                 _debug("attempt mkdir");
 722
 723                 ret = vfs_mkdir(dir->d_inode, subdir, 0700);
 724                 if (ret < 0)
 725                         goto mkdir_error;
 726
 727                 ASSERT(subdir->d_inode);
 728
 729                 _debug("mkdir -> %p{%p{ino=%lu}}",
 730                        subdir,
 731                        subdir->d_inode,
 732                        subdir->d_inode->i_ino);
 733         }
 734
 735         mutex_unlock(&dir->d_inode->i_mutex);
 736
 737         /* we need to make sure the subdir is a directory */
 738         ASSERT(subdir->d_inode);
 739
 740         if (!S_ISDIR(subdir->d_inode->i_mode)) {
 741                 kerror("%s is not a directory", dirname);
 742                 ret = -EIO;
 743                 goto check_error;
 744         }
 745
 746         ret = -EPERM;
 747         if (!subdir->d_inode->i_op ||
 748             !subdir->d_inode->i_op->setxattr ||
 749             !subdir->d_inode->i_op->getxattr ||
 750             !subdir->d_inode->i_op->lookup ||
 751             !subdir->d_inode->i_op->mkdir ||
 752             !subdir->d_inode->i_op->create ||
 753             !subdir->d_inode->i_op->rename ||
 754             !subdir->d_inode->i_op->rmdir ||
 755             !subdir->d_inode->i_op->unlink)
 756                 goto check_error;
 757
 758         _leave(" = [%lu]", subdir->d_inode->i_ino);
 759         return subdir;
 760
 761 check_error:
 762         dput(subdir);
 763         _leave(" = %d [check]", ret);
 764         return ERR_PTR(ret);
 765
 766 mkdir_error:
 767         mutex_unlock(&dir->d_inode->i_mutex);
 768         dput(subdir);
 769         kerror("mkdir %s failed with error %d", dirname, ret);
 770         return ERR_PTR(ret);
 771
 772 lookup_error:
 773         mutex_unlock(&dir->d_inode->i_mutex);
 774         ret = PTR_ERR(subdir);
 775         kerror("Lookup %s failed with error %d", dirname, ret);
 776         return ERR_PTR(ret);
 777
 778 nomem_d_alloc:
 779         mutex_unlock(&dir->d_inode->i_mutex);
 780         _leave(" = -ENOMEM");
 781         return ERR_PTR(-ENOMEM);
 782 }
 783
 784 /*
 785  * find out if an object is in use or not
 786  * - if finds object and it's not in use:
 787  *   - returns a pointer to the object and a reference on it
 788  *   - returns with the directory locked
 789  */
 790 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
 791                                               struct dentry *dir,
 792                                               char *filename)
 793 {
 794         struct cachefiles_object *object;
 795         struct rb_node *_n;
 796         struct dentry *victim;
 797         unsigned long start;
 798         int ret;
 799
 800         //_enter(",%*.*s/,%s",
 801         //       dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 802
 803         /* look up the victim */
 804         mutex_lock_nested(&dir->d_inode->i_mutex, 1);
 805
 806         start = jiffies;
 807         victim = lookup_one_len(filename, dir, strlen(filename));
 808         cachefiles_hist(cachefiles_lookup_histogram, start);
 809         if (IS_ERR(victim))
 810                 goto lookup_error;
 811
 812         //_debug("victim -> %p %s",
 813         //       victim, victim->d_inode ? "positive" : "negative");
 814
 815         /* if the object is no longer there then we probably retired the object
 816          * at the netfs's request whilst the cull was in progress
 817          */
 818         if (!victim->d_inode) {
 819                 mutex_unlock(&dir->d_inode->i_mutex);
 820                 dput(victim);
 821                 _leave(" = -ENOENT [absent]");
 822                 return ERR_PTR(-ENOENT);
 823         }
 824
 825         /* check to see if we're using this object */
 826         read_lock(&cache->active_lock);
 827
 828         _n = cache->active_nodes.rb_node;
 829
 830         while (_n) {
 831                 object = rb_entry(_n, struct cachefiles_object, active_node);
 832
 833                 if (object->dentry > victim)
 834                         _n = _n->rb_left;
 835                 else if (object->dentry < victim)
 836                         _n = _n->rb_right;
 837                 else
 838                         goto object_in_use;
 839         }
 840
 841         read_unlock(&cache->active_lock);
 842
 843         //_leave(" = %p", victim);
 844         return victim;
 845
 846 object_in_use:
 847         read_unlock(&cache->active_lock);
 848         mutex_unlock(&dir->d_inode->i_mutex);
 849         dput(victim);
 850         //_leave(" = -EBUSY [in use]");
 851         return ERR_PTR(-EBUSY);
 852
 853 lookup_error:
 854         mutex_unlock(&dir->d_inode->i_mutex);
 855         ret = PTR_ERR(victim);
 856         if (ret == -ENOENT) {
 857                 /* file or dir now absent - probably retired by netfs */
 858                 _leave(" = -ESTALE [absent]");
 859                 return ERR_PTR(-ESTALE);
 860         }
 861
 862         if (ret == -EIO) {
 863                 cachefiles_io_error(cache, "Lookup failed");
 864         } else if (ret != -ENOMEM) {
 865                 kerror("Internal error: %d", ret);
 866                 ret = -EIO;
 867         }
 868
 869         _leave(" = %d", ret);
 870         return ERR_PTR(ret);
 871 }
 872
 873 /*
 874  * cull an object if it's not in use
 875  * - called only by cache manager daemon
 876  */
 877 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
 878                     char *filename)
 879 {
 880         struct dentry *victim;
 881         int ret;
 882
 883         _enter(",%*.*s/,%s",
 884                dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 885
 886         victim = cachefiles_check_active(cache, dir, filename);
 887         if (IS_ERR(victim))
 888                 return PTR_ERR(victim);
 889
 890         _debug("victim -> %p %s",
 891                victim, victim->d_inode ? "positive" : "negative");
 892
 893         /* okay... the victim is not being used so we can cull it
 894          * - start by marking it as stale
 895          */
 896         _debug("victim is cullable");
 897
 898         ret = cachefiles_remove_object_xattr(cache, victim);
 899         if (ret < 0)
 900                 goto error_unlock;
 901
 902         /*  actually remove the victim (drops the dir mutex) */
 903         _debug("bury");
 904
 905         ret = cachefiles_bury_object(cache, dir, victim, false);
 906         if (ret < 0)
 907                 goto error;
 908
 909         dput(victim);
 910         _leave(" = 0");
 911         return 0;
 912
 913 error_unlock:
 914         mutex_unlock(&dir->d_inode->i_mutex);
 915 error:
 916         dput(victim);
 917         if (ret == -ENOENT) {
 918                 /* file or dir now absent - probably retired by netfs */
 919                 _leave(" = -ESTALE [absent]");
 920                 return -ESTALE;
 921         }
 922
 923         if (ret != -ENOMEM) {
 924                 kerror("Internal error: %d", ret);
 925                 ret = -EIO;
 926         }
 927
 928         _leave(" = %d", ret);
 929         return ret;
 930 }
 931
 932 /*
 933  * find out if an object is in use or not
 934  * - called only by cache manager daemon
 935  * - returns -EBUSY or 0 to indicate whether an object is in use or not
 936  */
 937 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
 938                             char *filename)
 939 {
 940         struct dentry *victim;
 941
 942         //_enter(",%*.*s/,%s",
 943         //       dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 944
 945         victim = cachefiles_check_active(cache, dir, filename);
 946         if (IS_ERR(victim))
 947                 return PTR_ERR(victim);
 948
 949         mutex_unlock(&dir->d_inode->i_mutex);
 950         dput(victim);
 951         //_leave(" = 0");
 952         return 0;
 953 }