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         pr_err("%sobject: OBJ%x\n", prefix, object->fscache.debug_id);
  39         pr_err("%sobjstate=%s fl=%lx wbusy=%x ev=%lx[%lx]\n",
  40                prefix, object->fscache.state->name,
  41                object->fscache.flags, work_busy(&object->fscache.work),
  42                object->fscache.events, object->fscache.event_mask);
  43         pr_err("%sops=%u inp=%u exc=%u\n",
  44                prefix, object->fscache.n_ops, object->fscache.n_in_progress,
  45                object->fscache.n_exclusive);
  46         pr_err("%sparent=%p\n",
  47                prefix, object->fscache.parent);
  48
  49         spin_lock(&object->fscache.lock);
  50         cookie = object->fscache.cookie;
  51         if (cookie) {
  52                 pr_err("%scookie=%p [pr=%p nd=%p fl=%lx]\n",
  53                        prefix,
  54                        object->fscache.cookie,
  55                        object->fscache.cookie->parent,
  56                        object->fscache.cookie->netfs_data,
  57                        object->fscache.cookie->flags);
  58                 if (keybuf && cookie->def)
  59                         keylen = cookie->def->get_key(cookie->netfs_data, keybuf,
  60                                                       CACHEFILES_KEYBUF_SIZE);
  61                 else
  62                         keylen = 0;
  63         } else {
  64                 pr_err("%scookie=NULL\n", prefix);
  65                 keylen = 0;
  66         }
  67         spin_unlock(&object->fscache.lock);
  68
  69         if (keylen) {
  70                 pr_err("%skey=[%u] '", prefix, keylen);
  71                 for (loop = 0; loop < keylen; loop++)
  72                         pr_cont("%02x", keybuf[loop]);
  73                 pr_cont("'\n");
  74         }
  75 }
  76
  77 /*
  78  * dump debugging info about a pair of objects
  79  */
  80 static noinline void cachefiles_printk_object(struct cachefiles_object *object,
  81                                               struct cachefiles_object *xobject)
  82 {
  83         u8 *keybuf;
  84
  85         keybuf = kmalloc(CACHEFILES_KEYBUF_SIZE, GFP_NOIO);
  86         if (object)
  87                 __cachefiles_printk_object(object, "", keybuf);
  88         if (xobject)
  89                 __cachefiles_printk_object(xobject, "x", keybuf);
  90         kfree(keybuf);
  91 }
  92
  93 /*
  94  * mark the owner of a dentry, if there is one, to indicate that that dentry
  95  * has been preemptively deleted
  96  * - the caller must hold the i_mutex on the dentry's parent as required to
  97  *   call vfs_unlink(), vfs_rmdir() or vfs_rename()
  98  */
  99 static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
 100                                           struct dentry *dentry)
 101 {
 102         struct cachefiles_object *object;
 103         struct rb_node *p;
 104
 105         _enter(",'%pd'", dentry);
 106
 107         write_lock(&cache->active_lock);
 108
 109         p = cache->active_nodes.rb_node;
 110         while (p) {
 111                 object = rb_entry(p, struct cachefiles_object, active_node);
 112                 if (object->dentry > dentry)
 113                         p = p->rb_left;
 114                 else if (object->dentry < dentry)
 115                         p = p->rb_right;
 116                 else
 117                         goto found_dentry;
 118         }
 119
 120         write_unlock(&cache->active_lock);
 121         _leave(" [no owner]");
 122         return;
 123
 124         /* found the dentry for  */
 125 found_dentry:
 126         kdebug("preemptive burial: OBJ%x [%s] %p",
 127                object->fscache.debug_id,
 128                object->fscache.state->name,
 129                dentry);
 130
 131         if (fscache_object_is_live(&object->fscache)) {
 132                 pr_err("\n");
 133                 pr_err("Error: Can't preemptively bury live object\n");
 134                 cachefiles_printk_object(object, NULL);
 135         } else if (test_and_set_bit(CACHEFILES_OBJECT_BURIED, &object->flags)) {
 136                 pr_err("Error: Object already preemptively buried\n");
 137         }
 138
 139         write_unlock(&cache->active_lock);
 140         _leave(" [owner marked]");
 141 }
 142
 143 /*
 144  * record the fact that an object is now active
 145  */
 146 static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
 147                                          struct cachefiles_object *object)
 148 {
 149         struct cachefiles_object *xobject;
 150         struct rb_node **_p, *_parent = NULL;
 151         struct dentry *dentry;
 152
 153         _enter(",%p", object);
 154
 155 try_again:
 156         write_lock(&cache->active_lock);
 157
 158         if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
 159                 pr_err("Error: Object already active\n");
 160                 cachefiles_printk_object(object, NULL);
 161                 BUG();
 162         }
 163
 164         dentry = object->dentry;
 165         _p = &cache->active_nodes.rb_node;
 166         while (*_p) {
 167                 _parent = *_p;
 168                 xobject = rb_entry(_parent,
 169                                    struct cachefiles_object, active_node);
 170
 171                 ASSERT(xobject != object);
 172
 173                 if (xobject->dentry > dentry)
 174                         _p = &(*_p)->rb_left;
 175                 else if (xobject->dentry < dentry)
 176                         _p = &(*_p)->rb_right;
 177                 else
 178                         goto wait_for_old_object;
 179         }
 180
 181         rb_link_node(&object->active_node, _parent, _p);
 182         rb_insert_color(&object->active_node, &cache->active_nodes);
 183
 184         write_unlock(&cache->active_lock);
 185         _leave(" = 0");
 186         return 0;
 187
 188         /* an old object from a previous incarnation is hogging the slot - we
 189          * need to wait for it to be destroyed */
 190 wait_for_old_object:
 191         if (fscache_object_is_live(&xobject->fscache)) {
 192                 pr_err("\n");
 193                 pr_err("Error: Unexpected object collision\n");
 194                 cachefiles_printk_object(object, xobject);
 195                 BUG();
 196         }
 197         atomic_inc(&xobject->usage);
 198         write_unlock(&cache->active_lock);
 199
 200         if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 201                 wait_queue_head_t *wq;
 202
 203                 signed long timeout = 60 * HZ;
 204                 wait_queue_t wait;
 205                 bool requeue;
 206
 207                 /* if the object we're waiting for is queued for processing,
 208                  * then just put ourselves on the queue behind it */
 209                 if (work_pending(&xobject->fscache.work)) {
 210                         _debug("queue OBJ%x behind OBJ%x immediately",
 211                                object->fscache.debug_id,
 212                                xobject->fscache.debug_id);
 213                         goto requeue;
 214                 }
 215
 216                 /* otherwise we sleep until either the object we're waiting for
 217                  * is done, or the fscache_object is congested */
 218                 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
 219                 init_wait(&wait);
 220                 requeue = false;
 221                 do {
 222                         prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
 223                         if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
 224                                 break;
 225
 226                         requeue = fscache_object_sleep_till_congested(&timeout);
 227                 } while (timeout > 0 && !requeue);
 228                 finish_wait(wq, &wait);
 229
 230                 if (requeue &&
 231                     test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 232                         _debug("queue OBJ%x behind OBJ%x after wait",
 233                                object->fscache.debug_id,
 234                                xobject->fscache.debug_id);
 235                         goto requeue;
 236                 }
 237
 238                 if (timeout <= 0) {
 239                         pr_err("\n");
 240                         pr_err("Error: Overlong wait for old active object to go away\n");
 241                         cachefiles_printk_object(object, xobject);
 242                         goto requeue;
 243                 }
 244         }
 245
 246         ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
 247
 248         cache->cache.ops->put_object(&xobject->fscache);
 249         goto try_again;
 250
 251 requeue:
 252         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 253         cache->cache.ops->put_object(&xobject->fscache);
 254         _leave(" = -ETIMEDOUT");
 255         return -ETIMEDOUT;
 256 }
 257
 258 /*
 259  * delete an object representation from the cache
 260  * - file backed objects are unlinked
 261  * - directory backed objects are stuffed into the graveyard for userspace to
 262  *   delete
 263  * - unlocks the directory mutex
 264  */
 265 static int cachefiles_bury_object(struct cachefiles_cache *cache,
 266                                   struct dentry *dir,
 267                                   struct dentry *rep,
 268                                   bool preemptive)
 269 {
 270         struct dentry *grave, *trap;
 271         struct path path, path_to_graveyard;
 272         char nbuffer[8 + 8 + 1];
 273         int ret;
 274
 275         _enter(",'%pd','%pd'", dir, rep);
 276
 277         _debug("remove %p from %p", rep, dir);
 278
 279         /* non-directories can just be unlinked */
 280         if (!d_is_dir(rep)) {
 281                 _debug("unlink stale object");
 282
 283                 path.mnt = cache->mnt;
 284                 path.dentry = dir;
 285                 ret = security_path_unlink(&path, rep);
 286                 if (ret < 0) {
 287                         cachefiles_io_error(cache, "Unlink security error");
 288                 } else {
 289                         ret = vfs_unlink(dir->d_inode, rep, NULL);
 290
 291                         if (preemptive)
 292                                 cachefiles_mark_object_buried(cache, rep);
 293                 }
 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 (!d_can_lookup(cache->graveyard)) {
 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         path.mnt = cache->mnt;
 383         path.dentry = dir;
 384         path_to_graveyard.mnt = cache->mnt;
 385         path_to_graveyard.dentry = cache->graveyard;
 386         ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0);
 387         if (ret < 0) {
 388                 cachefiles_io_error(cache, "Rename security error %d", ret);
 389         } else {
 390                 ret = vfs_rename(dir->d_inode, rep,
 391                                  cache->graveyard->d_inode, grave, NULL, 0);
 392                 if (ret != 0 && ret != -ENOMEM)
 393                         cachefiles_io_error(cache,
 394                                             "Rename failed with error %d", ret);
 395
 396                 if (preemptive)
 397                         cachefiles_mark_object_buried(cache, rep);
 398         }
 399
 400         unlock_rename(cache->graveyard, dir);
 401         dput(grave);
 402         _leave(" = 0");
 403         return 0;
 404 }
 405
 406 /*
 407  * delete an object representation from the cache
 408  */
 409 int cachefiles_delete_object(struct cachefiles_cache *cache,
 410                              struct cachefiles_object *object)
 411 {
 412         struct dentry *dir;
 413         int ret;
 414
 415         _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
 416
 417         ASSERT(object->dentry);
 418         ASSERT(object->dentry->d_inode);
 419         ASSERT(object->dentry->d_parent);
 420
 421         dir = dget_parent(object->dentry);
 422
 423         mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 424
 425         if (test_bit(CACHEFILES_OBJECT_BURIED, &object->flags)) {
 426                 /* object allocation for the same key preemptively deleted this
 427                  * object's file so that it could create its own file */
 428                 _debug("object preemptively buried");
 429                 mutex_unlock(&dir->d_inode->i_mutex);
 430                 ret = 0;
 431         } else {
 432                 /* we need to check that our parent is _still_ our parent - it
 433                  * may have been renamed */
 434                 if (dir == object->dentry->d_parent) {
 435                         ret = cachefiles_bury_object(cache, dir,
 436                                                      object->dentry, false);
 437                 } else {
 438                         /* it got moved, presumably by cachefilesd culling it,
 439                          * so it's no longer in the key path and we can ignore
 440                          * it */
 441                         mutex_unlock(&dir->d_inode->i_mutex);
 442                         ret = 0;
 443                 }
 444         }
 445
 446         dput(dir);
 447         _leave(" = %d", ret);
 448         return ret;
 449 }
 450
 451 /*
 452  * walk from the parent object to the child object through the backing
 453  * filesystem, creating directories as we go
 454  */
 455 int cachefiles_walk_to_object(struct cachefiles_object *parent,
 456                               struct cachefiles_object *object,
 457                               const char *key,
 458                               struct cachefiles_xattr *auxdata)
 459 {
 460         struct cachefiles_cache *cache;
 461         struct dentry *dir, *next = NULL;
 462         struct path path;
 463         unsigned long start;
 464         const char *name;
 465         int ret, nlen;
 466
 467         _enter("OBJ%x{%p},OBJ%x,%s,",
 468                parent->fscache.debug_id, parent->dentry,
 469                object->fscache.debug_id, key);
 470
 471         cache = container_of(parent->fscache.cache,
 472                              struct cachefiles_cache, cache);
 473         path.mnt = cache->mnt;
 474
 475         ASSERT(parent->dentry);
 476         ASSERT(parent->dentry->d_inode);
 477
 478         if (!(d_is_dir(parent->dentry))) {
 479                 // TODO: convert file to dir
 480                 _leave("looking up in none directory");
 481                 return -ENOBUFS;
 482         }
 483
 484         dir = dget(parent->dentry);
 485
 486 advance:
 487         /* attempt to transit the first directory component */
 488         name = key;
 489         nlen = strlen(key);
 490
 491         /* key ends in a double NUL */
 492         key = key + nlen + 1;
 493         if (!*key)
 494                 key = NULL;
 495
 496 lookup_again:
 497         /* search the current directory for the element name */
 498         _debug("lookup '%s'", name);
 499
 500         mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 501
 502         start = jiffies;
 503         next = lookup_one_len(name, dir, nlen);
 504         cachefiles_hist(cachefiles_lookup_histogram, start);
 505         if (IS_ERR(next))
 506                 goto lookup_error;
 507
 508         _debug("next -> %p %s", next, next->d_inode ? "positive" : "negative");
 509
 510         if (!key)
 511                 object->new = !next->d_inode;
 512
 513         /* if this element of the path doesn't exist, then the lookup phase
 514          * failed, and we can release any readers in the certain knowledge that
 515          * there's nothing for them to actually read */
 516         if (!next->d_inode)
 517                 fscache_object_lookup_negative(&object->fscache);
 518
 519         /* we need to create the object if it's negative */
 520         if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
 521                 /* index objects and intervening tree levels must be subdirs */
 522                 if (!next->d_inode) {
 523                         ret = cachefiles_has_space(cache, 1, 0);
 524                         if (ret < 0)
 525                                 goto create_error;
 526
 527                         path.dentry = dir;
 528                         ret = security_path_mkdir(&path, next, 0);
 529                         if (ret < 0)
 530                                 goto create_error;
 531                         start = jiffies;
 532                         ret = vfs_mkdir(dir->d_inode, next, 0);
 533                         cachefiles_hist(cachefiles_mkdir_histogram, start);
 534                         if (ret < 0)
 535                                 goto create_error;
 536
 537                         ASSERT(next->d_inode);
 538
 539                         _debug("mkdir -> %p{%p{ino=%lu}}",
 540                                next, next->d_inode, next->d_inode->i_ino);
 541
 542                 } else if (!d_can_lookup(next)) {
 543                         pr_err("inode %lu is not a directory\n",
 544                                next->d_inode->i_ino);
 545                         ret = -ENOBUFS;
 546                         goto error;
 547                 }
 548
 549         } else {
 550                 /* non-index objects start out life as files */
 551                 if (!next->d_inode) {
 552                         ret = cachefiles_has_space(cache, 1, 0);
 553                         if (ret < 0)
 554                                 goto create_error;
 555
 556                         path.dentry = dir;
 557                         ret = security_path_mknod(&path, next, S_IFREG, 0);
 558                         if (ret < 0)
 559                                 goto create_error;
 560                         start = jiffies;
 561                         ret = vfs_create(dir->d_inode, next, S_IFREG, true);
 562                         cachefiles_hist(cachefiles_create_histogram, start);
 563                         if (ret < 0)
 564                                 goto create_error;
 565
 566                         ASSERT(next->d_inode);
 567
 568                         _debug("create -> %p{%p{ino=%lu}}",
 569                                next, next->d_inode, next->d_inode->i_ino);
 570
 571                 } else if (!d_can_lookup(next) &&
 572                            !d_is_reg(next)
 573                            ) {
 574                         pr_err("inode %lu is not a file or directory\n",
 575                                next->d_inode->i_ino);
 576                         ret = -ENOBUFS;
 577                         goto error;
 578                 }
 579         }
 580
 581         /* process the next component */
 582         if (key) {
 583                 _debug("advance");
 584                 mutex_unlock(&dir->d_inode->i_mutex);
 585                 dput(dir);
 586                 dir = next;
 587                 next = NULL;
 588                 goto advance;
 589         }
 590
 591         /* we've found the object we were looking for */
 592         object->dentry = next;
 593
 594         /* if we've found that the terminal object exists, then we need to
 595          * check its attributes and delete it if it's out of date */
 596         if (!object->new) {
 597                 _debug("validate '%pd'", next);
 598
 599                 ret = cachefiles_check_object_xattr(object, auxdata);
 600                 if (ret == -ESTALE) {
 601                         /* delete the object (the deleter drops the directory
 602                          * mutex) */
 603                         object->dentry = NULL;
 604
 605                         ret = cachefiles_bury_object(cache, dir, next, true);
 606                         dput(next);
 607                         next = NULL;
 608
 609                         if (ret < 0)
 610                                 goto delete_error;
 611
 612                         _debug("redo lookup");
 613                         goto lookup_again;
 614                 }
 615         }
 616
 617         /* note that we're now using this object */
 618         ret = cachefiles_mark_object_active(cache, object);
 619
 620         mutex_unlock(&dir->d_inode->i_mutex);
 621         dput(dir);
 622         dir = NULL;
 623
 624         if (ret == -ETIMEDOUT)
 625                 goto mark_active_timed_out;
 626
 627         _debug("=== OBTAINED_OBJECT ===");
 628
 629         if (object->new) {
 630                 /* attach data to a newly constructed terminal object */
 631                 ret = cachefiles_set_object_xattr(object, auxdata);
 632                 if (ret < 0)
 633                         goto check_error;
 634         } else {
 635                 /* always update the atime on an object we've just looked up
 636                  * (this is used to keep track of culling, and atimes are only
 637                  * updated by read, write and readdir but not lookup or
 638                  * open) */
 639                 path.dentry = next;
 640                 touch_atime(&path);
 641         }
 642
 643         /* open a file interface onto a data file */
 644         if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
 645                 if (d_is_reg(object->dentry)) {
 646                         const struct address_space_operations *aops;
 647
 648                         ret = -EPERM;
 649                         aops = object->dentry->d_inode->i_mapping->a_ops;
 650                         if (!aops->bmap)
 651                                 goto check_error;
 652
 653                         object->backer = object->dentry;
 654                 } else {
 655                         BUG(); // TODO: open file in data-class subdir
 656                 }
 657         }
 658
 659         object->new = 0;
 660         fscache_obtained_object(&object->fscache);
 661
 662         _leave(" = 0 [%lu]", object->dentry->d_inode->i_ino);
 663         return 0;
 664
 665 create_error:
 666         _debug("create error %d", ret);
 667         if (ret == -EIO)
 668                 cachefiles_io_error(cache, "Create/mkdir failed");
 669         goto error;
 670
 671 mark_active_timed_out:
 672         _debug("mark active timed out");
 673         goto release_dentry;
 674
 675 check_error:
 676         _debug("check error %d", ret);
 677         write_lock(&cache->active_lock);
 678         rb_erase(&object->active_node, &cache->active_nodes);
 679         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 680         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
 681         write_unlock(&cache->active_lock);
 682 release_dentry:
 683         dput(object->dentry);
 684         object->dentry = NULL;
 685         goto error_out;
 686
 687 delete_error:
 688         _debug("delete error %d", ret);
 689         goto error_out2;
 690
 691 lookup_error:
 692         _debug("lookup error %ld", PTR_ERR(next));
 693         ret = PTR_ERR(next);
 694         if (ret == -EIO)
 695                 cachefiles_io_error(cache, "Lookup failed");
 696         next = NULL;
 697 error:
 698         mutex_unlock(&dir->d_inode->i_mutex);
 699         dput(next);
 700 error_out2:
 701         dput(dir);
 702 error_out:
 703         _leave(" = error %d", -ret);
 704         return ret;
 705 }
 706
 707 /*
 708  * get a subdirectory
 709  */
 710 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
 711                                         struct dentry *dir,
 712                                         const char *dirname)
 713 {
 714         struct dentry *subdir;
 715         unsigned long start;
 716         struct path path;
 717         int ret;
 718
 719         _enter(",,%s", dirname);
 720
 721         /* search the current directory for the element name */
 722         mutex_lock(&dir->d_inode->i_mutex);
 723
 724         start = jiffies;
 725         subdir = lookup_one_len(dirname, dir, strlen(dirname));
 726         cachefiles_hist(cachefiles_lookup_histogram, start);
 727         if (IS_ERR(subdir)) {
 728                 if (PTR_ERR(subdir) == -ENOMEM)
 729                         goto nomem_d_alloc;
 730                 goto lookup_error;
 731         }
 732
 733         _debug("subdir -> %p %s",
 734                subdir, subdir->d_inode ? "positive" : "negative");
 735
 736         /* we need to create the subdir if it doesn't exist yet */
 737         if (!subdir->d_inode) {
 738                 ret = cachefiles_has_space(cache, 1, 0);
 739                 if (ret < 0)
 740                         goto mkdir_error;
 741
 742                 _debug("attempt mkdir");
 743
 744                 path.mnt = cache->mnt;
 745                 path.dentry = dir;
 746                 ret = security_path_mkdir(&path, subdir, 0700);
 747                 if (ret < 0)
 748                         goto mkdir_error;
 749                 ret = vfs_mkdir(dir->d_inode, subdir, 0700);
 750                 if (ret < 0)
 751                         goto mkdir_error;
 752
 753                 ASSERT(subdir->d_inode);
 754
 755                 _debug("mkdir -> %p{%p{ino=%lu}}",
 756                        subdir,
 757                        subdir->d_inode,
 758                        subdir->d_inode->i_ino);
 759         }
 760
 761         mutex_unlock(&dir->d_inode->i_mutex);
 762
 763         /* we need to make sure the subdir is a directory */
 764         ASSERT(subdir->d_inode);
 765
 766         if (!d_can_lookup(subdir)) {
 767                 pr_err("%s is not a directory\n", dirname);
 768                 ret = -EIO;
 769                 goto check_error;
 770         }
 771
 772         ret = -EPERM;
 773         if (!subdir->d_inode->i_op->setxattr ||
 774             !subdir->d_inode->i_op->getxattr ||
 775             !subdir->d_inode->i_op->lookup ||
 776             !subdir->d_inode->i_op->mkdir ||
 777             !subdir->d_inode->i_op->create ||
 778             (!subdir->d_inode->i_op->rename &&
 779              !subdir->d_inode->i_op->rename2) ||
 780             !subdir->d_inode->i_op->rmdir ||
 781             !subdir->d_inode->i_op->unlink)
 782                 goto check_error;
 783
 784         _leave(" = [%lu]", subdir->d_inode->i_ino);
 785         return subdir;
 786
 787 check_error:
 788         dput(subdir);
 789         _leave(" = %d [check]", ret);
 790         return ERR_PTR(ret);
 791
 792 mkdir_error:
 793         mutex_unlock(&dir->d_inode->i_mutex);
 794         dput(subdir);
 795         pr_err("mkdir %s failed with error %d\n", dirname, ret);
 796         return ERR_PTR(ret);
 797
 798 lookup_error:
 799         mutex_unlock(&dir->d_inode->i_mutex);
 800         ret = PTR_ERR(subdir);
 801         pr_err("Lookup %s failed with error %d\n", dirname, ret);
 802         return ERR_PTR(ret);
 803
 804 nomem_d_alloc:
 805         mutex_unlock(&dir->d_inode->i_mutex);
 806         _leave(" = -ENOMEM");
 807         return ERR_PTR(-ENOMEM);
 808 }
 809
 810 /*
 811  * find out if an object is in use or not
 812  * - if finds object and it's not in use:
 813  *   - returns a pointer to the object and a reference on it
 814  *   - returns with the directory locked
 815  */
 816 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
 817                                               struct dentry *dir,
 818                                               char *filename)
 819 {
 820         struct cachefiles_object *object;
 821         struct rb_node *_n;
 822         struct dentry *victim;
 823         unsigned long start;
 824         int ret;
 825
 826         //_enter(",%pd/,%s",
 827         //       dir, filename);
 828
 829         /* look up the victim */
 830         mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 831
 832         start = jiffies;
 833         victim = lookup_one_len(filename, dir, strlen(filename));
 834         cachefiles_hist(cachefiles_lookup_histogram, start);
 835         if (IS_ERR(victim))
 836                 goto lookup_error;
 837
 838         //_debug("victim -> %p %s",
 839         //       victim, victim->d_inode ? "positive" : "negative");
 840
 841         /* if the object is no longer there then we probably retired the object
 842          * at the netfs's request whilst the cull was in progress
 843          */
 844         if (!victim->d_inode) {
 845                 mutex_unlock(&dir->d_inode->i_mutex);
 846                 dput(victim);
 847                 _leave(" = -ENOENT [absent]");
 848                 return ERR_PTR(-ENOENT);
 849         }
 850
 851         /* check to see if we're using this object */
 852         read_lock(&cache->active_lock);
 853
 854         _n = cache->active_nodes.rb_node;
 855
 856         while (_n) {
 857                 object = rb_entry(_n, struct cachefiles_object, active_node);
 858
 859                 if (object->dentry > victim)
 860                         _n = _n->rb_left;
 861                 else if (object->dentry < victim)
 862                         _n = _n->rb_right;
 863                 else
 864                         goto object_in_use;
 865         }
 866
 867         read_unlock(&cache->active_lock);
 868
 869         //_leave(" = %p", victim);
 870         return victim;
 871
 872 object_in_use:
 873         read_unlock(&cache->active_lock);
 874         mutex_unlock(&dir->d_inode->i_mutex);
 875         dput(victim);
 876         //_leave(" = -EBUSY [in use]");
 877         return ERR_PTR(-EBUSY);
 878
 879 lookup_error:
 880         mutex_unlock(&dir->d_inode->i_mutex);
 881         ret = PTR_ERR(victim);
 882         if (ret == -ENOENT) {
 883                 /* file or dir now absent - probably retired by netfs */
 884                 _leave(" = -ESTALE [absent]");
 885                 return ERR_PTR(-ESTALE);
 886         }
 887
 888         if (ret == -EIO) {
 889                 cachefiles_io_error(cache, "Lookup failed");
 890         } else if (ret != -ENOMEM) {
 891                 pr_err("Internal error: %d\n", ret);
 892                 ret = -EIO;
 893         }
 894
 895         _leave(" = %d", ret);
 896         return ERR_PTR(ret);
 897 }
 898
 899 /*
 900  * cull an object if it's not in use
 901  * - called only by cache manager daemon
 902  */
 903 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
 904                     char *filename)
 905 {
 906         struct dentry *victim;
 907         int ret;
 908
 909         _enter(",%pd/,%s", dir, filename);
 910
 911         victim = cachefiles_check_active(cache, dir, filename);
 912         if (IS_ERR(victim))
 913                 return PTR_ERR(victim);
 914
 915         _debug("victim -> %p %s",
 916                victim, victim->d_inode ? "positive" : "negative");
 917
 918         /* okay... the victim is not being used so we can cull it
 919          * - start by marking it as stale
 920          */
 921         _debug("victim is cullable");
 922
 923         ret = cachefiles_remove_object_xattr(cache, victim);
 924         if (ret < 0)
 925                 goto error_unlock;
 926
 927         /*  actually remove the victim (drops the dir mutex) */
 928         _debug("bury");
 929
 930         ret = cachefiles_bury_object(cache, dir, victim, false);
 931         if (ret < 0)
 932                 goto error;
 933
 934         dput(victim);
 935         _leave(" = 0");
 936         return 0;
 937
 938 error_unlock:
 939         mutex_unlock(&dir->d_inode->i_mutex);
 940 error:
 941         dput(victim);
 942         if (ret == -ENOENT) {
 943                 /* file or dir now absent - probably retired by netfs */
 944                 _leave(" = -ESTALE [absent]");
 945                 return -ESTALE;
 946         }
 947
 948         if (ret != -ENOMEM) {
 949                 pr_err("Internal error: %d\n", ret);
 950                 ret = -EIO;
 951         }
 952
 953         _leave(" = %d", ret);
 954         return ret;
 955 }
 956
 957 /*
 958  * find out if an object is in use or not
 959  * - called only by cache manager daemon
 960  * - returns -EBUSY or 0 to indicate whether an object is in use or not
 961  */
 962 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
 963                             char *filename)
 964 {
 965         struct dentry *victim;
 966
 967         //_enter(",%pd/,%s",
 968         //       dir, filename);
 969
 970         victim = cachefiles_check_active(cache, dir, filename);
 971         if (IS_ERR(victim))
 972                 return PTR_ERR(victim);
 973
 974         mutex_unlock(&dir->d_inode->i_mutex);
 975         dput(victim);
 976         //_leave(" = 0");
 977         return 0;
 978 }