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 <linux/xattr.h>
  24 #include "internal.h"
  25
  26 #define CACHEFILES_KEYBUF_SIZE 512
  27
  28 /*
  29  * dump debugging info about an object
  30  */
  31 static noinline
  32 void __cachefiles_printk_object(struct cachefiles_object *object,
  33                                 const char *prefix)
  34 {
  35         struct fscache_cookie *cookie;
  36         const u8 *k;
  37         unsigned loop;
  38
  39         pr_err("%sobject: OBJ%x\n", prefix, object->fscache.debug_id);
  40         pr_err("%sobjstate=%s fl=%lx wbusy=%x ev=%lx[%lx]\n",
  41                prefix, object->fscache.state->name,
  42                object->fscache.flags, work_busy(&object->fscache.work),
  43                object->fscache.events, object->fscache.event_mask);
  44         pr_err("%sops=%u inp=%u exc=%u\n",
  45                prefix, object->fscache.n_ops, object->fscache.n_in_progress,
  46                object->fscache.n_exclusive);
  47         pr_err("%sparent=%p\n",
  48                prefix, object->fscache.parent);
  49
  50         spin_lock(&object->fscache.lock);
  51         cookie = object->fscache.cookie;
  52         if (cookie) {
  53                 pr_err("%scookie=%p [pr=%p nd=%p fl=%lx]\n",
  54                        prefix,
  55                        object->fscache.cookie,
  56                        object->fscache.cookie->parent,
  57                        object->fscache.cookie->netfs_data,
  58                        object->fscache.cookie->flags);
  59                 pr_err("%skey=[%u] '", prefix, cookie->key_len);
  60                 k = (cookie->key_len <= sizeof(cookie->inline_key)) ?
  61                         cookie->inline_key : cookie->key;
  62                 for (loop = 0; loop < cookie->key_len; loop++)
  63                         pr_cont("%02x", k[loop]);
  64                 pr_cont("'\n");
  65         } else {
  66                 pr_err("%scookie=NULL\n", prefix);
  67         }
  68         spin_unlock(&object->fscache.lock);
  69 }
  70
  71 /*
  72  * dump debugging info about a pair of objects
  73  */
  74 static noinline void cachefiles_printk_object(struct cachefiles_object *object,
  75                                               struct cachefiles_object *xobject)
  76 {
  77         if (object)
  78                 __cachefiles_printk_object(object, "");
  79         if (xobject)
  80                 __cachefiles_printk_object(xobject, "x");
  81 }
  82
  83 /*
  84  * mark the owner of a dentry, if there is one, to indicate that that dentry
  85  * has been preemptively deleted
  86  * - the caller must hold the i_mutex on the dentry's parent as required to
  87  *   call vfs_unlink(), vfs_rmdir() or vfs_rename()
  88  */
  89 static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
  90                                           struct dentry *dentry,
  91                                           enum fscache_why_object_killed why)
  92 {
  93         struct cachefiles_object *object;
  94         struct rb_node *p;
  95
  96         _enter(",'%pd'", dentry);
  97
  98         write_lock(&cache->active_lock);
  99
 100         p = cache->active_nodes.rb_node;
 101         while (p) {
 102                 object = rb_entry(p, struct cachefiles_object, active_node);
 103                 if (object->dentry > dentry)
 104                         p = p->rb_left;
 105                 else if (object->dentry < dentry)
 106                         p = p->rb_right;
 107                 else
 108                         goto found_dentry;
 109         }
 110
 111         write_unlock(&cache->active_lock);
 112         trace_cachefiles_mark_buried(NULL, dentry, why);
 113         _leave(" [no owner]");
 114         return;
 115
 116         /* found the dentry for  */
 117 found_dentry:
 118         kdebug("preemptive burial: OBJ%x [%s] %p",
 119                object->fscache.debug_id,
 120                object->fscache.state->name,
 121                dentry);
 122
 123         trace_cachefiles_mark_buried(object, dentry, why);
 124
 125         if (fscache_object_is_live(&object->fscache)) {
 126                 pr_err("\n");
 127                 pr_err("Error: Can't preemptively bury live object\n");
 128                 cachefiles_printk_object(object, NULL);
 129         } else {
 130                 if (why != FSCACHE_OBJECT_IS_STALE)
 131                         fscache_object_mark_killed(&object->fscache, why);
 132         }
 133
 134         write_unlock(&cache->active_lock);
 135         _leave(" [owner marked]");
 136 }
 137
 138 /*
 139  * record the fact that an object is now active
 140  */
 141 static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
 142                                          struct cachefiles_object *object)
 143 {
 144         struct cachefiles_object *xobject;
 145         struct rb_node **_p, *_parent = NULL;
 146         struct dentry *dentry;
 147
 148         _enter(",%p", object);
 149
 150 try_again:
 151         write_lock(&cache->active_lock);
 152
 153         dentry = object->dentry;
 154         trace_cachefiles_mark_active(object, dentry);
 155
 156         if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
 157                 pr_err("Error: Object already active\n");
 158                 cachefiles_printk_object(object, NULL);
 159                 BUG();
 160         }
 161
 162         _p = &cache->active_nodes.rb_node;
 163         while (*_p) {
 164                 _parent = *_p;
 165                 xobject = rb_entry(_parent,
 166                                    struct cachefiles_object, active_node);
 167
 168                 ASSERT(xobject != object);
 169
 170                 if (xobject->dentry > dentry)
 171                         _p = &(*_p)->rb_left;
 172                 else if (xobject->dentry < dentry)
 173                         _p = &(*_p)->rb_right;
 174                 else
 175                         goto wait_for_old_object;
 176         }
 177
 178         rb_link_node(&object->active_node, _parent, _p);
 179         rb_insert_color(&object->active_node, &cache->active_nodes);
 180
 181         write_unlock(&cache->active_lock);
 182         _leave(" = 0");
 183         return 0;
 184
 185         /* an old object from a previous incarnation is hogging the slot - we
 186          * need to wait for it to be destroyed */
 187 wait_for_old_object:
 188         trace_cachefiles_wait_active(object, dentry, xobject);
 189         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 190
 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         }
 196         atomic_inc(&xobject->usage);
 197         write_unlock(&cache->active_lock);
 198
 199         if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 200                 wait_queue_head_t *wq;
 201
 202                 signed long timeout = 60 * HZ;
 203                 wait_queue_entry_t wait;
 204                 bool requeue;
 205
 206                 /* if the object we're waiting for is queued for processing,
 207                  * then just put ourselves on the queue behind it */
 208                 if (work_pending(&xobject->fscache.work)) {
 209                         _debug("queue OBJ%x behind OBJ%x immediately",
 210                                object->fscache.debug_id,
 211                                xobject->fscache.debug_id);
 212                         goto requeue;
 213                 }
 214
 215                 /* otherwise we sleep until either the object we're waiting for
 216                  * is done, or the fscache_object is congested */
 217                 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
 218                 init_wait(&wait);
 219                 requeue = false;
 220                 do {
 221                         prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
 222                         if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
 223                                 break;
 224
 225                         requeue = fscache_object_sleep_till_congested(&timeout);
 226                 } while (timeout > 0 && !requeue);
 227                 finish_wait(wq, &wait);
 228
 229                 if (requeue &&
 230                     test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 231                         _debug("queue OBJ%x behind OBJ%x after wait",
 232                                object->fscache.debug_id,
 233                                xobject->fscache.debug_id);
 234                         goto requeue;
 235                 }
 236
 237                 if (timeout <= 0) {
 238                         pr_err("\n");
 239                         pr_err("Error: Overlong wait for old active object to go away\n");
 240                         cachefiles_printk_object(object, xobject);
 241                         goto requeue;
 242                 }
 243         }
 244
 245         ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
 246
 247         cache->cache.ops->put_object(&xobject->fscache, cachefiles_obj_put_wait_retry);
 248         goto try_again;
 249
 250 requeue:
 251         cache->cache.ops->put_object(&xobject->fscache, cachefiles_obj_put_wait_timeo);
 252         _leave(" = -ETIMEDOUT");
 253         return -ETIMEDOUT;
 254 }
 255
 256 /*
 257  * Mark an object as being inactive.
 258  */
 259 void cachefiles_mark_object_inactive(struct cachefiles_cache *cache,
 260                                      struct cachefiles_object *object,
 261                                      blkcnt_t i_blocks)
 262 {
 263         struct dentry *dentry = object->dentry;
 264         struct inode *inode = d_backing_inode(dentry);
 265
 266         trace_cachefiles_mark_inactive(object, dentry, inode);
 267
 268         write_lock(&cache->active_lock);
 269         rb_erase(&object->active_node, &cache->active_nodes);
 270         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 271         write_unlock(&cache->active_lock);
 272
 273         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
 274
 275         /* This object can now be culled, so we need to let the daemon know
 276          * that there is something it can remove if it needs to.
 277          */
 278         atomic_long_add(i_blocks, &cache->b_released);
 279         if (atomic_inc_return(&cache->f_released))
 280                 cachefiles_state_changed(cache);
 281 }
 282
 283 /*
 284  * delete an object representation from the cache
 285  * - file backed objects are unlinked
 286  * - directory backed objects are stuffed into the graveyard for userspace to
 287  *   delete
 288  * - unlocks the directory mutex
 289  */
 290 static int cachefiles_bury_object(struct cachefiles_cache *cache,
 291                                   struct cachefiles_object *object,
 292                                   struct dentry *dir,
 293                                   struct dentry *rep,
 294                                   bool preemptive,
 295                                   enum fscache_why_object_killed why)
 296 {
 297         struct dentry *grave, *trap;
 298         struct path path, path_to_graveyard;
 299         char nbuffer[8 + 8 + 1];
 300         int ret;
 301
 302         _enter(",'%pd','%pd'", dir, rep);
 303
 304         _debug("remove %p from %p", rep, dir);
 305
 306         /* non-directories can just be unlinked */
 307         if (!d_is_dir(rep)) {
 308                 _debug("unlink stale object");
 309
 310                 path.mnt = cache->mnt;
 311                 path.dentry = dir;
 312                 ret = security_path_unlink(&path, rep);
 313                 if (ret < 0) {
 314                         cachefiles_io_error(cache, "Unlink security error");
 315                 } else {
 316                         trace_cachefiles_unlink(object, rep, why);
 317                         ret = vfs_unlink(d_inode(dir), rep, NULL);
 318
 319                         if (preemptive)
 320                                 cachefiles_mark_object_buried(cache, rep, why);
 321                 }
 322
 323                 inode_unlock(d_inode(dir));
 324
 325                 if (ret == -EIO)
 326                         cachefiles_io_error(cache, "Unlink failed");
 327
 328                 _leave(" = %d", ret);
 329                 return ret;
 330         }
 331
 332         /* directories have to be moved to the graveyard */
 333         _debug("move stale object to graveyard");
 334         inode_unlock(d_inode(dir));
 335
 336 try_again:
 337         /* first step is to make up a grave dentry in the graveyard */
 338         sprintf(nbuffer, "%08x%08x",
 339                 (uint32_t) get_seconds(),
 340                 (uint32_t) atomic_inc_return(&cache->gravecounter));
 341
 342         /* do the multiway lock magic */
 343         trap = lock_rename(cache->graveyard, dir);
 344
 345         /* do some checks before getting the grave dentry */
 346         if (rep->d_parent != dir) {
 347                 /* the entry was probably culled when we dropped the parent dir
 348                  * lock */
 349                 unlock_rename(cache->graveyard, dir);
 350                 _leave(" = 0 [culled?]");
 351                 return 0;
 352         }
 353
 354         if (!d_can_lookup(cache->graveyard)) {
 355                 unlock_rename(cache->graveyard, dir);
 356                 cachefiles_io_error(cache, "Graveyard no longer a directory");
 357                 return -EIO;
 358         }
 359
 360         if (trap == rep) {
 361                 unlock_rename(cache->graveyard, dir);
 362                 cachefiles_io_error(cache, "May not make directory loop");
 363                 return -EIO;
 364         }
 365
 366         if (d_mountpoint(rep)) {
 367                 unlock_rename(cache->graveyard, dir);
 368                 cachefiles_io_error(cache, "Mountpoint in cache");
 369                 return -EIO;
 370         }
 371
 372         grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
 373         if (IS_ERR(grave)) {
 374                 unlock_rename(cache->graveyard, dir);
 375
 376                 if (PTR_ERR(grave) == -ENOMEM) {
 377                         _leave(" = -ENOMEM");
 378                         return -ENOMEM;
 379                 }
 380
 381                 cachefiles_io_error(cache, "Lookup error %ld",
 382                                     PTR_ERR(grave));
 383                 return -EIO;
 384         }
 385
 386         if (d_is_positive(grave)) {
 387                 unlock_rename(cache->graveyard, dir);
 388                 dput(grave);
 389                 grave = NULL;
 390                 cond_resched();
 391                 goto try_again;
 392         }
 393
 394         if (d_mountpoint(grave)) {
 395                 unlock_rename(cache->graveyard, dir);
 396                 dput(grave);
 397                 cachefiles_io_error(cache, "Mountpoint in graveyard");
 398                 return -EIO;
 399         }
 400
 401         /* target should not be an ancestor of source */
 402         if (trap == grave) {
 403                 unlock_rename(cache->graveyard, dir);
 404                 dput(grave);
 405                 cachefiles_io_error(cache, "May not make directory loop");
 406                 return -EIO;
 407         }
 408
 409         /* attempt the rename */
 410         path.mnt = cache->mnt;
 411         path.dentry = dir;
 412         path_to_graveyard.mnt = cache->mnt;
 413         path_to_graveyard.dentry = cache->graveyard;
 414         ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0);
 415         if (ret < 0) {
 416                 cachefiles_io_error(cache, "Rename security error %d", ret);
 417         } else {
 418                 trace_cachefiles_rename(object, rep, grave, why);
 419                 ret = vfs_rename(d_inode(dir), rep,
 420                                  d_inode(cache->graveyard), grave, NULL, 0);
 421                 if (ret != 0 && ret != -ENOMEM)
 422                         cachefiles_io_error(cache,
 423                                             "Rename failed with error %d", ret);
 424
 425                 if (preemptive)
 426                         cachefiles_mark_object_buried(cache, rep, why);
 427         }
 428
 429         unlock_rename(cache->graveyard, dir);
 430         dput(grave);
 431         _leave(" = 0");
 432         return 0;
 433 }
 434
 435 /*
 436  * delete an object representation from the cache
 437  */
 438 int cachefiles_delete_object(struct cachefiles_cache *cache,
 439                              struct cachefiles_object *object)
 440 {
 441         struct dentry *dir;
 442         int ret;
 443
 444         _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
 445
 446         ASSERT(object->dentry);
 447         ASSERT(d_backing_inode(object->dentry));
 448         ASSERT(object->dentry->d_parent);
 449
 450         dir = dget_parent(object->dentry);
 451
 452         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
 453
 454         if (test_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->fscache.flags)) {
 455                 /* object allocation for the same key preemptively deleted this
 456                  * object's file so that it could create its own file */
 457                 _debug("object preemptively buried");
 458                 inode_unlock(d_inode(dir));
 459                 ret = 0;
 460         } else {
 461                 /* we need to check that our parent is _still_ our parent - it
 462                  * may have been renamed */
 463                 if (dir == object->dentry->d_parent) {
 464                         ret = cachefiles_bury_object(cache, object, dir,
 465                                                      object->dentry, false,
 466                                                      FSCACHE_OBJECT_WAS_RETIRED);
 467                 } else {
 468                         /* it got moved, presumably by cachefilesd culling it,
 469                          * so it's no longer in the key path and we can ignore
 470                          * it */
 471                         inode_unlock(d_inode(dir));
 472                         ret = 0;
 473                 }
 474         }
 475
 476         dput(dir);
 477         _leave(" = %d", ret);
 478         return ret;
 479 }
 480
 481 /*
 482  * walk from the parent object to the child object through the backing
 483  * filesystem, creating directories as we go
 484  */
 485 int cachefiles_walk_to_object(struct cachefiles_object *parent,
 486                               struct cachefiles_object *object,
 487                               const char *key,
 488                               struct cachefiles_xattr *auxdata)
 489 {
 490         struct cachefiles_cache *cache;
 491         struct dentry *dir, *next = NULL;
 492         struct inode *inode;
 493         struct path path;
 494         unsigned long start;
 495         const char *name;
 496         int ret, nlen;
 497
 498         _enter("OBJ%x{%p},OBJ%x,%s,",
 499                parent->fscache.debug_id, parent->dentry,
 500                object->fscache.debug_id, key);
 501
 502         cache = container_of(parent->fscache.cache,
 503                              struct cachefiles_cache, cache);
 504         path.mnt = cache->mnt;
 505
 506         ASSERT(parent->dentry);
 507         ASSERT(d_backing_inode(parent->dentry));
 508
 509         if (!(d_is_dir(parent->dentry))) {
 510                 // TODO: convert file to dir
 511                 _leave("looking up in none directory");
 512                 return -ENOBUFS;
 513         }
 514
 515         dir = dget(parent->dentry);
 516
 517 advance:
 518         /* attempt to transit the first directory component */
 519         name = key;
 520         nlen = strlen(key);
 521
 522         /* key ends in a double NUL */
 523         key = key + nlen + 1;
 524         if (!*key)
 525                 key = NULL;
 526
 527 lookup_again:
 528         /* search the current directory for the element name */
 529         _debug("lookup '%s'", name);
 530
 531         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
 532
 533         start = jiffies;
 534         next = lookup_one_len(name, dir, nlen);
 535         cachefiles_hist(cachefiles_lookup_histogram, start);
 536         if (IS_ERR(next)) {
 537                 trace_cachefiles_lookup(object, next, NULL);
 538                 goto lookup_error;
 539         }
 540
 541         inode = d_backing_inode(next);
 542         trace_cachefiles_lookup(object, next, inode);
 543         _debug("next -> %p %s", next, inode ? "positive" : "negative");
 544
 545         if (!key)
 546                 object->new = !inode;
 547
 548         /* if this element of the path doesn't exist, then the lookup phase
 549          * failed, and we can release any readers in the certain knowledge that
 550          * there's nothing for them to actually read */
 551         if (d_is_negative(next))
 552                 fscache_object_lookup_negative(&object->fscache);
 553
 554         /* we need to create the object if it's negative */
 555         if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
 556                 /* index objects and intervening tree levels must be subdirs */
 557                 if (d_is_negative(next)) {
 558                         ret = cachefiles_has_space(cache, 1, 0);
 559                         if (ret < 0)
 560                                 goto no_space_error;
 561
 562                         path.dentry = dir;
 563                         ret = security_path_mkdir(&path, next, 0);
 564                         if (ret < 0)
 565                                 goto create_error;
 566                         start = jiffies;
 567                         ret = vfs_mkdir(d_inode(dir), next, 0);
 568                         cachefiles_hist(cachefiles_mkdir_histogram, start);
 569                         if (!key)
 570                                 trace_cachefiles_mkdir(object, next, ret);
 571                         if (ret < 0)
 572                                 goto create_error;
 573
 574                         if (unlikely(d_unhashed(next))) {
 575                                 dput(next);
 576                                 inode_unlock(d_inode(dir));
 577                                 goto lookup_again;
 578                         }
 579                         ASSERT(d_backing_inode(next));
 580
 581                         _debug("mkdir -> %p{%p{ino=%lu}}",
 582                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
 583
 584                 } else if (!d_can_lookup(next)) {
 585                         pr_err("inode %lu is not a directory\n",
 586                                d_backing_inode(next)->i_ino);
 587                         ret = -ENOBUFS;
 588                         goto error;
 589                 }
 590
 591         } else {
 592                 /* non-index objects start out life as files */
 593                 if (d_is_negative(next)) {
 594                         ret = cachefiles_has_space(cache, 1, 0);
 595                         if (ret < 0)
 596                                 goto no_space_error;
 597
 598                         path.dentry = dir;
 599                         ret = security_path_mknod(&path, next, S_IFREG, 0);
 600                         if (ret < 0)
 601                                 goto create_error;
 602                         start = jiffies;
 603                         ret = vfs_create(d_inode(dir), next, S_IFREG, true);
 604                         cachefiles_hist(cachefiles_create_histogram, start);
 605                         trace_cachefiles_create(object, next, ret);
 606                         if (ret < 0)
 607                                 goto create_error;
 608
 609                         ASSERT(d_backing_inode(next));
 610
 611                         _debug("create -> %p{%p{ino=%lu}}",
 612                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
 613
 614                 } else if (!d_can_lookup(next) &&
 615                            !d_is_reg(next)
 616                            ) {
 617                         pr_err("inode %lu is not a file or directory\n",
 618                                d_backing_inode(next)->i_ino);
 619                         ret = -ENOBUFS;
 620                         goto error;
 621                 }
 622         }
 623
 624         /* process the next component */
 625         if (key) {
 626                 _debug("advance");
 627                 inode_unlock(d_inode(dir));
 628                 dput(dir);
 629                 dir = next;
 630                 next = NULL;
 631                 goto advance;
 632         }
 633
 634         /* we've found the object we were looking for */
 635         object->dentry = next;
 636
 637         /* if we've found that the terminal object exists, then we need to
 638          * check its attributes and delete it if it's out of date */
 639         if (!object->new) {
 640                 _debug("validate '%pd'", next);
 641
 642                 ret = cachefiles_check_object_xattr(object, auxdata);
 643                 if (ret == -ESTALE) {
 644                         /* delete the object (the deleter drops the directory
 645                          * mutex) */
 646                         object->dentry = NULL;
 647
 648                         ret = cachefiles_bury_object(cache, object, dir, next,
 649                                                      true,
 650                                                      FSCACHE_OBJECT_IS_STALE);
 651                         dput(next);
 652                         next = NULL;
 653
 654                         if (ret < 0)
 655                                 goto delete_error;
 656
 657                         _debug("redo lookup");
 658                         fscache_object_retrying_stale(&object->fscache);
 659                         goto lookup_again;
 660                 }
 661         }
 662
 663         /* note that we're now using this object */
 664         ret = cachefiles_mark_object_active(cache, object);
 665
 666         inode_unlock(d_inode(dir));
 667         dput(dir);
 668         dir = NULL;
 669
 670         if (ret == -ETIMEDOUT)
 671                 goto mark_active_timed_out;
 672
 673         _debug("=== OBTAINED_OBJECT ===");
 674
 675         if (object->new) {
 676                 /* attach data to a newly constructed terminal object */
 677                 ret = cachefiles_set_object_xattr(object, auxdata);
 678                 if (ret < 0)
 679                         goto check_error;
 680         } else {
 681                 /* always update the atime on an object we've just looked up
 682                  * (this is used to keep track of culling, and atimes are only
 683                  * updated by read, write and readdir but not lookup or
 684                  * open) */
 685                 path.dentry = next;
 686                 touch_atime(&path);
 687         }
 688
 689         /* open a file interface onto a data file */
 690         if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
 691                 if (d_is_reg(object->dentry)) {
 692                         const struct address_space_operations *aops;
 693
 694                         ret = -EPERM;
 695                         aops = d_backing_inode(object->dentry)->i_mapping->a_ops;
 696                         if (!aops->bmap)
 697                                 goto check_error;
 698                         if (object->dentry->d_sb->s_blocksize > PAGE_SIZE)
 699                                 goto check_error;
 700
 701                         object->backer = object->dentry;
 702                 } else {
 703                         BUG(); // TODO: open file in data-class subdir
 704                 }
 705         }
 706
 707         object->new = 0;
 708         fscache_obtained_object(&object->fscache);
 709
 710         _leave(" = 0 [%lu]", d_backing_inode(object->dentry)->i_ino);
 711         return 0;
 712
 713 no_space_error:
 714         fscache_object_mark_killed(&object->fscache, FSCACHE_OBJECT_NO_SPACE);
 715 create_error:
 716         _debug("create error %d", ret);
 717         if (ret == -EIO)
 718                 cachefiles_io_error(cache, "Create/mkdir failed");
 719         goto error;
 720
 721 mark_active_timed_out:
 722         _debug("mark active timed out");
 723         goto release_dentry;
 724
 725 check_error:
 726         _debug("check error %d", ret);
 727         cachefiles_mark_object_inactive(
 728                 cache, object, d_backing_inode(object->dentry)->i_blocks);
 729 release_dentry:
 730         dput(object->dentry);
 731         object->dentry = NULL;
 732         goto error_out;
 733
 734 delete_error:
 735         _debug("delete error %d", ret);
 736         goto error_out2;
 737
 738 lookup_error:
 739         _debug("lookup error %ld", PTR_ERR(next));
 740         ret = PTR_ERR(next);
 741         if (ret == -EIO)
 742                 cachefiles_io_error(cache, "Lookup failed");
 743         next = NULL;
 744 error:
 745         inode_unlock(d_inode(dir));
 746         dput(next);
 747 error_out2:
 748         dput(dir);
 749 error_out:
 750         _leave(" = error %d", -ret);
 751         return ret;
 752 }
 753
 754 /*
 755  * get a subdirectory
 756  */
 757 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
 758                                         struct dentry *dir,
 759                                         const char *dirname)
 760 {
 761         struct dentry *subdir;
 762         unsigned long start;
 763         struct path path;
 764         int ret;
 765
 766         _enter(",,%s", dirname);
 767
 768         /* search the current directory for the element name */
 769         inode_lock(d_inode(dir));
 770
 771 retry:
 772         start = jiffies;
 773         subdir = lookup_one_len(dirname, dir, strlen(dirname));
 774         cachefiles_hist(cachefiles_lookup_histogram, start);
 775         if (IS_ERR(subdir)) {
 776                 if (PTR_ERR(subdir) == -ENOMEM)
 777                         goto nomem_d_alloc;
 778                 goto lookup_error;
 779         }
 780
 781         _debug("subdir -> %p %s",
 782                subdir, d_backing_inode(subdir) ? "positive" : "negative");
 783
 784         /* we need to create the subdir if it doesn't exist yet */
 785         if (d_is_negative(subdir)) {
 786                 ret = cachefiles_has_space(cache, 1, 0);
 787                 if (ret < 0)
 788                         goto mkdir_error;
 789
 790                 _debug("attempt mkdir");
 791
 792                 path.mnt = cache->mnt;
 793                 path.dentry = dir;
 794                 ret = security_path_mkdir(&path, subdir, 0700);
 795                 if (ret < 0)
 796                         goto mkdir_error;
 797                 ret = vfs_mkdir(d_inode(dir), subdir, 0700);
 798                 if (ret < 0)
 799                         goto mkdir_error;
 800
 801                 if (unlikely(d_unhashed(subdir))) {
 802                         dput(subdir);
 803                         goto retry;
 804                 }
 805                 ASSERT(d_backing_inode(subdir));
 806
 807                 _debug("mkdir -> %p{%p{ino=%lu}}",
 808                        subdir,
 809                        d_backing_inode(subdir),
 810                        d_backing_inode(subdir)->i_ino);
 811         }
 812
 813         inode_unlock(d_inode(dir));
 814
 815         /* we need to make sure the subdir is a directory */
 816         ASSERT(d_backing_inode(subdir));
 817
 818         if (!d_can_lookup(subdir)) {
 819                 pr_err("%s is not a directory\n", dirname);
 820                 ret = -EIO;
 821                 goto check_error;
 822         }
 823
 824         ret = -EPERM;
 825         if (!(d_backing_inode(subdir)->i_opflags & IOP_XATTR) ||
 826             !d_backing_inode(subdir)->i_op->lookup ||
 827             !d_backing_inode(subdir)->i_op->mkdir ||
 828             !d_backing_inode(subdir)->i_op->create ||
 829             !d_backing_inode(subdir)->i_op->rename ||
 830             !d_backing_inode(subdir)->i_op->rmdir ||
 831             !d_backing_inode(subdir)->i_op->unlink)
 832                 goto check_error;
 833
 834         _leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
 835         return subdir;
 836
 837 check_error:
 838         dput(subdir);
 839         _leave(" = %d [check]", ret);
 840         return ERR_PTR(ret);
 841
 842 mkdir_error:
 843         inode_unlock(d_inode(dir));
 844         dput(subdir);
 845         pr_err("mkdir %s failed with error %d\n", dirname, ret);
 846         return ERR_PTR(ret);
 847
 848 lookup_error:
 849         inode_unlock(d_inode(dir));
 850         ret = PTR_ERR(subdir);
 851         pr_err("Lookup %s failed with error %d\n", dirname, ret);
 852         return ERR_PTR(ret);
 853
 854 nomem_d_alloc:
 855         inode_unlock(d_inode(dir));
 856         _leave(" = -ENOMEM");
 857         return ERR_PTR(-ENOMEM);
 858 }
 859
 860 /*
 861  * find out if an object is in use or not
 862  * - if finds object and it's not in use:
 863  *   - returns a pointer to the object and a reference on it
 864  *   - returns with the directory locked
 865  */
 866 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
 867                                               struct dentry *dir,
 868                                               char *filename)
 869 {
 870         struct cachefiles_object *object;
 871         struct rb_node *_n;
 872         struct dentry *victim;
 873         unsigned long start;
 874         int ret;
 875
 876         //_enter(",%pd/,%s",
 877         //       dir, filename);
 878
 879         /* look up the victim */
 880         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
 881
 882         start = jiffies;
 883         victim = lookup_one_len(filename, dir, strlen(filename));
 884         cachefiles_hist(cachefiles_lookup_histogram, start);
 885         if (IS_ERR(victim))
 886                 goto lookup_error;
 887
 888         //_debug("victim -> %p %s",
 889         //       victim, d_backing_inode(victim) ? "positive" : "negative");
 890
 891         /* if the object is no longer there then we probably retired the object
 892          * at the netfs's request whilst the cull was in progress
 893          */
 894         if (d_is_negative(victim)) {
 895                 inode_unlock(d_inode(dir));
 896                 dput(victim);
 897                 _leave(" = -ENOENT [absent]");
 898                 return ERR_PTR(-ENOENT);
 899         }
 900
 901         /* check to see if we're using this object */
 902         read_lock(&cache->active_lock);
 903
 904         _n = cache->active_nodes.rb_node;
 905
 906         while (_n) {
 907                 object = rb_entry(_n, struct cachefiles_object, active_node);
 908
 909                 if (object->dentry > victim)
 910                         _n = _n->rb_left;
 911                 else if (object->dentry < victim)
 912                         _n = _n->rb_right;
 913                 else
 914                         goto object_in_use;
 915         }
 916
 917         read_unlock(&cache->active_lock);
 918
 919         //_leave(" = %p", victim);
 920         return victim;
 921
 922 object_in_use:
 923         read_unlock(&cache->active_lock);
 924         inode_unlock(d_inode(dir));
 925         dput(victim);
 926         //_leave(" = -EBUSY [in use]");
 927         return ERR_PTR(-EBUSY);
 928
 929 lookup_error:
 930         inode_unlock(d_inode(dir));
 931         ret = PTR_ERR(victim);
 932         if (ret == -ENOENT) {
 933                 /* file or dir now absent - probably retired by netfs */
 934                 _leave(" = -ESTALE [absent]");
 935                 return ERR_PTR(-ESTALE);
 936         }
 937
 938         if (ret == -EIO) {
 939                 cachefiles_io_error(cache, "Lookup failed");
 940         } else if (ret != -ENOMEM) {
 941                 pr_err("Internal error: %d\n", ret);
 942                 ret = -EIO;
 943         }
 944
 945         _leave(" = %d", ret);
 946         return ERR_PTR(ret);
 947 }
 948
 949 /*
 950  * cull an object if it's not in use
 951  * - called only by cache manager daemon
 952  */
 953 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
 954                     char *filename)
 955 {
 956         struct dentry *victim;
 957         int ret;
 958
 959         _enter(",%pd/,%s", dir, filename);
 960
 961         victim = cachefiles_check_active(cache, dir, filename);
 962         if (IS_ERR(victim))
 963                 return PTR_ERR(victim);
 964
 965         _debug("victim -> %p %s",
 966                victim, d_backing_inode(victim) ? "positive" : "negative");
 967
 968         /* okay... the victim is not being used so we can cull it
 969          * - start by marking it as stale
 970          */
 971         _debug("victim is cullable");
 972
 973         ret = cachefiles_remove_object_xattr(cache, victim);
 974         if (ret < 0)
 975                 goto error_unlock;
 976
 977         /*  actually remove the victim (drops the dir mutex) */
 978         _debug("bury");
 979
 980         ret = cachefiles_bury_object(cache, NULL, dir, victim, false,
 981                                      FSCACHE_OBJECT_WAS_CULLED);
 982         if (ret < 0)
 983                 goto error;
 984
 985         dput(victim);
 986         _leave(" = 0");
 987         return 0;
 988
 989 error_unlock:
 990         inode_unlock(d_inode(dir));
 991 error:
 992         dput(victim);
 993         if (ret == -ENOENT) {
 994                 /* file or dir now absent - probably retired by netfs */
 995                 _leave(" = -ESTALE [absent]");
 996                 return -ESTALE;
 997         }
 998
 999         if (ret != -ENOMEM) {
1000                 pr_err("Internal error: %d\n", ret);
1001                 ret = -EIO;
1002         }
1003
1004         _leave(" = %d", ret);
1005         return ret;
1006 }
1007
1008 /*
1009  * find out if an object is in use or not
1010  * - called only by cache manager daemon
1011  * - returns -EBUSY or 0 to indicate whether an object is in use or not
1012  */
1013 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
1014                             char *filename)
1015 {
1016         struct dentry *victim;
1017
1018         //_enter(",%pd/,%s",
1019         //       dir, filename);
1020
1021         victim = cachefiles_check_active(cache, dir, filename);
1022         if (IS_ERR(victim))
1023                 return PTR_ERR(victim);
1024
1025         inode_unlock(d_inode(dir));
1026         dput(victim);
1027         //_leave(" = 0");
1028         return 0;
1029 }