fs/cachefiles/namei.c

   1 // SPDX-License-Identifier: GPL-2.0-or-later
   2 /* CacheFiles path walking and related routines
   3  *
   4  * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
   5  * Written by David Howells ([email protected])
   6  */
   7
   8 #include <linux/module.h>
   9 #include <linux/sched.h>
  10 #include <linux/file.h>
  11 #include <linux/fs.h>
  12 #include <linux/fsnotify.h>
  13 #include <linux/quotaops.h>
  14 #include <linux/xattr.h>
  15 #include <linux/mount.h>
  16 #include <linux/namei.h>
  17 #include <linux/security.h>
  18 #include <linux/slab.h>
  19 #include "internal.h"
  20
  21 #define CACHEFILES_KEYBUF_SIZE 512
  22
  23 /*
  24  * dump debugging info about an object
  25  */
  26 static noinline
  27 void __cachefiles_printk_object(struct cachefiles_object *object,
  28                                 const char *prefix)
  29 {
  30         struct fscache_cookie *cookie;
  31         const u8 *k;
  32         unsigned loop;
  33
  34         pr_err("%sobject: OBJ%x\n", prefix, object->fscache.debug_id);
  35         pr_err("%sobjstate=%s fl=%lx wbusy=%x ev=%lx[%lx]\n",
  36                prefix, object->fscache.state->name,
  37                object->fscache.flags, work_busy(&object->fscache.work),
  38                object->fscache.events, object->fscache.event_mask);
  39         pr_err("%sops=%u inp=%u exc=%u\n",
  40                prefix, object->fscache.n_ops, object->fscache.n_in_progress,
  41                object->fscache.n_exclusive);
  42         pr_err("%sparent=%x\n",
  43                prefix, object->fscache.parent ? object->fscache.parent->debug_id : 0);
  44
  45         spin_lock(&object->fscache.lock);
  46         cookie = object->fscache.cookie;
  47         if (cookie) {
  48                 pr_err("%scookie=%x [pr=%x nd=%p fl=%lx]\n",
  49                        prefix,
  50                        cookie->debug_id,
  51                        cookie->parent ? cookie->parent->debug_id : 0,
  52                        cookie->netfs_data,
  53                        cookie->flags);
  54                 pr_err("%skey=[%u] '", prefix, cookie->key_len);
  55                 k = (cookie->key_len <= sizeof(cookie->inline_key)) ?
  56                         cookie->inline_key : cookie->key;
  57                 for (loop = 0; loop < cookie->key_len; loop++)
  58                         pr_cont("%02x", k[loop]);
  59                 pr_cont("'\n");
  60         } else {
  61                 pr_err("%scookie=NULL\n", prefix);
  62         }
  63         spin_unlock(&object->fscache.lock);
  64 }
  65
  66 /*
  67  * dump debugging info about a pair of objects
  68  */
  69 static noinline void cachefiles_printk_object(struct cachefiles_object *object,
  70                                               struct cachefiles_object *xobject)
  71 {
  72         if (object)
  73                 __cachefiles_printk_object(object, "");
  74         if (xobject)
  75                 __cachefiles_printk_object(xobject, "x");
  76 }
  77
  78 /*
  79  * mark the owner of a dentry, if there is one, to indicate that that dentry
  80  * has been preemptively deleted
  81  * - the caller must hold the i_mutex on the dentry's parent as required to
  82  *   call vfs_unlink(), vfs_rmdir() or vfs_rename()
  83  */
  84 static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
  85                                           struct dentry *dentry,
  86                                           enum fscache_why_object_killed why)
  87 {
  88         struct cachefiles_object *object;
  89         struct rb_node *p;
  90
  91         _enter(",'%pd'", dentry);
  92
  93         write_lock(&cache->active_lock);
  94
  95         p = cache->active_nodes.rb_node;
  96         while (p) {
  97                 object = rb_entry(p, struct cachefiles_object, active_node);
  98                 if (object->dentry > dentry)
  99                         p = p->rb_left;
 100                 else if (object->dentry < dentry)
 101                         p = p->rb_right;
 102                 else
 103                         goto found_dentry;
 104         }
 105
 106         write_unlock(&cache->active_lock);
 107         trace_cachefiles_mark_buried(NULL, dentry, why);
 108         _leave(" [no owner]");
 109         return;
 110
 111         /* found the dentry for  */
 112 found_dentry:
 113         kdebug("preemptive burial: OBJ%x [%s] %pd",
 114                object->fscache.debug_id,
 115                object->fscache.state->name,
 116                dentry);
 117
 118         trace_cachefiles_mark_buried(object, dentry, why);
 119
 120         if (fscache_object_is_live(&object->fscache)) {
 121                 pr_err("\n");
 122                 pr_err("Error: Can't preemptively bury live object\n");
 123                 cachefiles_printk_object(object, NULL);
 124         } else {
 125                 if (why != FSCACHE_OBJECT_IS_STALE)
 126                         fscache_object_mark_killed(&object->fscache, why);
 127         }
 128
 129         write_unlock(&cache->active_lock);
 130         _leave(" [owner marked]");
 131 }
 132
 133 /*
 134  * record the fact that an object is now active
 135  */
 136 static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
 137                                          struct cachefiles_object *object)
 138 {
 139         struct cachefiles_object *xobject;
 140         struct rb_node **_p, *_parent = NULL;
 141         struct dentry *dentry;
 142
 143         _enter(",%x", object->fscache.debug_id);
 144
 145 try_again:
 146         write_lock(&cache->active_lock);
 147
 148         dentry = object->dentry;
 149         trace_cachefiles_mark_active(object, dentry);
 150
 151         if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
 152                 pr_err("Error: Object already active\n");
 153                 cachefiles_printk_object(object, NULL);
 154                 BUG();
 155         }
 156
 157         _p = &cache->active_nodes.rb_node;
 158         while (*_p) {
 159                 _parent = *_p;
 160                 xobject = rb_entry(_parent,
 161                                    struct cachefiles_object, active_node);
 162
 163                 ASSERT(xobject != object);
 164
 165                 if (xobject->dentry > dentry)
 166                         _p = &(*_p)->rb_left;
 167                 else if (xobject->dentry < dentry)
 168                         _p = &(*_p)->rb_right;
 169                 else
 170                         goto wait_for_old_object;
 171         }
 172
 173         rb_link_node(&object->active_node, _parent, _p);
 174         rb_insert_color(&object->active_node, &cache->active_nodes);
 175
 176         write_unlock(&cache->active_lock);
 177         _leave(" = 0");
 178         return 0;
 179
 180         /* an old object from a previous incarnation is hogging the slot - we
 181          * need to wait for it to be destroyed */
 182 wait_for_old_object:
 183         trace_cachefiles_wait_active(object, dentry, xobject);
 184         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 185
 186         if (fscache_object_is_live(&xobject->fscache)) {
 187                 pr_err("\n");
 188                 pr_err("Error: Unexpected object collision\n");
 189                 cachefiles_printk_object(object, xobject);
 190         }
 191         atomic_inc(&xobject->usage);
 192         write_unlock(&cache->active_lock);
 193
 194         if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 195                 wait_queue_head_t *wq;
 196
 197                 signed long timeout = 60 * HZ;
 198                 wait_queue_entry_t wait;
 199                 bool requeue;
 200
 201                 /* if the object we're waiting for is queued for processing,
 202                  * then just put ourselves on the queue behind it */
 203                 if (work_pending(&xobject->fscache.work)) {
 204                         _debug("queue OBJ%x behind OBJ%x immediately",
 205                                object->fscache.debug_id,
 206                                xobject->fscache.debug_id);
 207                         goto requeue;
 208                 }
 209
 210                 /* otherwise we sleep until either the object we're waiting for
 211                  * is done, or the fscache_object is congested */
 212                 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
 213                 init_wait(&wait);
 214                 requeue = false;
 215                 do {
 216                         prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
 217                         if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
 218                                 break;
 219
 220                         requeue = fscache_object_sleep_till_congested(&timeout);
 221                 } while (timeout > 0 && !requeue);
 222                 finish_wait(wq, &wait);
 223
 224                 if (requeue &&
 225                     test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 226                         _debug("queue OBJ%x behind OBJ%x after wait",
 227                                object->fscache.debug_id,
 228                                xobject->fscache.debug_id);
 229                         goto requeue;
 230                 }
 231
 232                 if (timeout <= 0) {
 233                         pr_err("\n");
 234                         pr_err("Error: Overlong wait for old active object to go away\n");
 235                         cachefiles_printk_object(object, xobject);
 236                         goto requeue;
 237                 }
 238         }
 239
 240         ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
 241
 242         cache->cache.ops->put_object(&xobject->fscache,
 243                 (enum fscache_obj_ref_trace)cachefiles_obj_put_wait_retry);
 244         goto try_again;
 245
 246 requeue:
 247         cache->cache.ops->put_object(&xobject->fscache,
 248                 (enum fscache_obj_ref_trace)cachefiles_obj_put_wait_timeo);
 249         _leave(" = -ETIMEDOUT");
 250         return -ETIMEDOUT;
 251 }
 252
 253 /*
 254  * Mark an object as being inactive.
 255  */
 256 void cachefiles_mark_object_inactive(struct cachefiles_cache *cache,
 257                                      struct cachefiles_object *object,
 258                                      blkcnt_t i_blocks)
 259 {
 260         struct dentry *dentry = object->dentry;
 261         struct inode *inode = d_backing_inode(dentry);
 262
 263         trace_cachefiles_mark_inactive(object, dentry, inode);
 264
 265         write_lock(&cache->active_lock);
 266         rb_erase(&object->active_node, &cache->active_nodes);
 267         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 268         write_unlock(&cache->active_lock);
 269
 270         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
 271
 272         /* This object can now be culled, so we need to let the daemon know
 273          * that there is something it can remove if it needs to.
 274          */
 275         atomic_long_add(i_blocks, &cache->b_released);
 276         if (atomic_inc_return(&cache->f_released))
 277                 cachefiles_state_changed(cache);
 278 }
 279
 280 /*
 281  * delete an object representation from the cache
 282  * - file backed objects are unlinked
 283  * - directory backed objects are stuffed into the graveyard for userspace to
 284  *   delete
 285  * - unlocks the directory mutex
 286  */
 287 static int cachefiles_bury_object(struct cachefiles_cache *cache,
 288                                   struct cachefiles_object *object,
 289                                   struct dentry *dir,
 290                                   struct dentry *rep,
 291                                   bool preemptive,
 292                                   enum fscache_why_object_killed why)
 293 {
 294         struct dentry *grave, *trap;
 295         struct path path, path_to_graveyard;
 296         char nbuffer[8 + 8 + 1];
 297         int ret;
 298
 299         _enter(",'%pd','%pd'", dir, rep);
 300
 301         /* non-directories can just be unlinked */
 302         if (!d_is_dir(rep)) {
 303                 _debug("unlink stale object");
 304
 305                 path.mnt = cache->mnt;
 306                 path.dentry = dir;
 307                 ret = security_path_unlink(&path, rep);
 308                 if (ret < 0) {
 309                         cachefiles_io_error(cache, "Unlink security error");
 310                 } else {
 311                         trace_cachefiles_unlink(object, rep, why);
 312                         ret = vfs_unlink(&init_user_ns, d_inode(dir), rep,
 313                                          NULL);
 314
 315                         if (preemptive)
 316                                 cachefiles_mark_object_buried(cache, rep, why);
 317                 }
 318
 319                 inode_unlock(d_inode(dir));
 320
 321                 if (ret == -EIO)
 322                         cachefiles_io_error(cache, "Unlink failed");
 323
 324                 _leave(" = %d", ret);
 325                 return ret;
 326         }
 327
 328         /* directories have to be moved to the graveyard */
 329         _debug("move stale object to graveyard");
 330         inode_unlock(d_inode(dir));
 331
 332 try_again:
 333         /* first step is to make up a grave dentry in the graveyard */
 334         sprintf(nbuffer, "%08x%08x",
 335                 (uint32_t) ktime_get_real_seconds(),
 336                 (uint32_t) atomic_inc_return(&cache->gravecounter));
 337
 338         /* do the multiway lock magic */
 339         trap = lock_rename(cache->graveyard, dir);
 340
 341         /* do some checks before getting the grave dentry */
 342         if (rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) {
 343                 /* the entry was probably culled when we dropped the parent dir
 344                  * lock */
 345                 unlock_rename(cache->graveyard, dir);
 346                 _leave(" = 0 [culled?]");
 347                 return 0;
 348         }
 349
 350         if (!d_can_lookup(cache->graveyard)) {
 351                 unlock_rename(cache->graveyard, dir);
 352                 cachefiles_io_error(cache, "Graveyard no longer a directory");
 353                 return -EIO;
 354         }
 355
 356         if (trap == rep) {
 357                 unlock_rename(cache->graveyard, dir);
 358                 cachefiles_io_error(cache, "May not make directory loop");
 359                 return -EIO;
 360         }
 361
 362         if (d_mountpoint(rep)) {
 363                 unlock_rename(cache->graveyard, dir);
 364                 cachefiles_io_error(cache, "Mountpoint in cache");
 365                 return -EIO;
 366         }
 367
 368         grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
 369         if (IS_ERR(grave)) {
 370                 unlock_rename(cache->graveyard, dir);
 371
 372                 if (PTR_ERR(grave) == -ENOMEM) {
 373                         _leave(" = -ENOMEM");
 374                         return -ENOMEM;
 375                 }
 376
 377                 cachefiles_io_error(cache, "Lookup error %ld",
 378                                     PTR_ERR(grave));
 379                 return -EIO;
 380         }
 381
 382         if (d_is_positive(grave)) {
 383                 unlock_rename(cache->graveyard, dir);
 384                 dput(grave);
 385                 grave = NULL;
 386                 cond_resched();
 387                 goto try_again;
 388         }
 389
 390         if (d_mountpoint(grave)) {
 391                 unlock_rename(cache->graveyard, dir);
 392                 dput(grave);
 393                 cachefiles_io_error(cache, "Mountpoint in graveyard");
 394                 return -EIO;
 395         }
 396
 397         /* target should not be an ancestor of source */
 398         if (trap == grave) {
 399                 unlock_rename(cache->graveyard, dir);
 400                 dput(grave);
 401                 cachefiles_io_error(cache, "May not make directory loop");
 402                 return -EIO;
 403         }
 404
 405         /* attempt the rename */
 406         path.mnt = cache->mnt;
 407         path.dentry = dir;
 408         path_to_graveyard.mnt = cache->mnt;
 409         path_to_graveyard.dentry = cache->graveyard;
 410         ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0);
 411         if (ret < 0) {
 412                 cachefiles_io_error(cache, "Rename security error %d", ret);
 413         } else {
 414                 struct renamedata rd = {
 415                         .old_mnt_userns = &init_user_ns,
 416                         .old_dir        = d_inode(dir),
 417                         .old_dentry     = rep,
 418                         .new_mnt_userns = &init_user_ns,
 419                         .new_dir        = d_inode(cache->graveyard),
 420                         .new_dentry     = grave,
 421                 };
 422                 trace_cachefiles_rename(object, rep, grave, why);
 423                 ret = vfs_rename(&rd);
 424                 if (ret != 0 && ret != -ENOMEM)
 425                         cachefiles_io_error(cache,
 426                                             "Rename failed with error %d", ret);
 427
 428                 if (preemptive)
 429                         cachefiles_mark_object_buried(cache, rep, why);
 430         }
 431
 432         unlock_rename(cache->graveyard, dir);
 433         dput(grave);
 434         _leave(" = 0");
 435         return 0;
 436 }
 437
 438 /*
 439  * delete an object representation from the cache
 440  */
 441 int cachefiles_delete_object(struct cachefiles_cache *cache,
 442                              struct cachefiles_object *object)
 443 {
 444         struct dentry *dir;
 445         int ret;
 446
 447         _enter(",OBJ%x{%pd}", object->fscache.debug_id, object->dentry);
 448
 449         ASSERT(object->dentry);
 450         ASSERT(d_backing_inode(object->dentry));
 451         ASSERT(object->dentry->d_parent);
 452
 453         dir = dget_parent(object->dentry);
 454
 455         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
 456
 457         if (test_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->fscache.flags)) {
 458                 /* object allocation for the same key preemptively deleted this
 459                  * object's file so that it could create its own file */
 460                 _debug("object preemptively buried");
 461                 inode_unlock(d_inode(dir));
 462                 ret = 0;
 463         } else {
 464                 /* we need to check that our parent is _still_ our parent - it
 465                  * may have been renamed */
 466                 if (dir == object->dentry->d_parent) {
 467                         ret = cachefiles_bury_object(cache, object, dir,
 468                                                      object->dentry, false,
 469                                                      FSCACHE_OBJECT_WAS_RETIRED);
 470                 } else {
 471                         /* it got moved, presumably by cachefilesd culling it,
 472                          * so it's no longer in the key path and we can ignore
 473                          * it */
 474                         inode_unlock(d_inode(dir));
 475                         ret = 0;
 476                 }
 477         }
 478
 479         dput(dir);
 480         _leave(" = %d", ret);
 481         return ret;
 482 }
 483
 484 /*
 485  * walk from the parent object to the child object through the backing
 486  * filesystem, creating directories as we go
 487  */
 488 int cachefiles_walk_to_object(struct cachefiles_object *parent,
 489                               struct cachefiles_object *object,
 490                               const char *key,
 491                               struct cachefiles_xattr *auxdata)
 492 {
 493         struct cachefiles_cache *cache;
 494         struct dentry *dir, *next = NULL;
 495         struct inode *inode;
 496         struct path path;
 497         const char *name;
 498         int ret, nlen;
 499
 500         _enter("OBJ%x{%pd},OBJ%x,%s,",
 501                parent->fscache.debug_id, parent->dentry,
 502                object->fscache.debug_id, key);
 503
 504         cache = container_of(parent->fscache.cache,
 505                              struct cachefiles_cache, cache);
 506         path.mnt = cache->mnt;
 507
 508         ASSERT(parent->dentry);
 509         ASSERT(d_backing_inode(parent->dentry));
 510
 511         if (!(d_is_dir(parent->dentry))) {
 512                 // TODO: convert file to dir
 513                 _leave("looking up in none directory");
 514                 return -ENOBUFS;
 515         }
 516
 517         dir = dget(parent->dentry);
 518
 519 advance:
 520         /* attempt to transit the first directory component */
 521         name = key;
 522         nlen = strlen(key);
 523
 524         /* key ends in a double NUL */
 525         key = key + nlen + 1;
 526         if (!*key)
 527                 key = NULL;
 528
 529 lookup_again:
 530         /* search the current directory for the element name */
 531         _debug("lookup '%s'", name);
 532
 533         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
 534
 535         next = lookup_one_len(name, dir, nlen);
 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 -> %pd %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                         ret = vfs_mkdir(&init_user_ns, d_inode(dir), next, 0);
 567                         if (!key)
 568                                 trace_cachefiles_mkdir(object, next, ret);
 569                         if (ret < 0)
 570                                 goto create_error;
 571
 572                         if (unlikely(d_unhashed(next))) {
 573                                 dput(next);
 574                                 inode_unlock(d_inode(dir));
 575                                 goto lookup_again;
 576                         }
 577                         ASSERT(d_backing_inode(next));
 578
 579                         _debug("mkdir -> %pd{ino=%lu}",
 580                                next, d_backing_inode(next)->i_ino);
 581
 582                 } else if (!d_can_lookup(next)) {
 583                         pr_err("inode %lu is not a directory\n",
 584                                d_backing_inode(next)->i_ino);
 585                         ret = -ENOBUFS;
 586                         goto error;
 587                 }
 588
 589         } else {
 590                 /* non-index objects start out life as files */
 591                 if (d_is_negative(next)) {
 592                         ret = cachefiles_has_space(cache, 1, 0);
 593                         if (ret < 0)
 594                                 goto no_space_error;
 595
 596                         path.dentry = dir;
 597                         ret = security_path_mknod(&path, next, S_IFREG, 0);
 598                         if (ret < 0)
 599                                 goto create_error;
 600                         ret = vfs_create(&init_user_ns, d_inode(dir), next,
 601                                          S_IFREG, true);
 602                         trace_cachefiles_create(object, next, ret);
 603                         if (ret < 0)
 604                                 goto create_error;
 605
 606                         ASSERT(d_backing_inode(next));
 607
 608                         _debug("create -> %pd{ino=%lu}",
 609                                next, d_backing_inode(next)->i_ino);
 610
 611                 } else if (!d_can_lookup(next) &&
 612                            !d_is_reg(next)
 613                            ) {
 614                         pr_err("inode %lu is not a file or directory\n",
 615                                d_backing_inode(next)->i_ino);
 616                         ret = -ENOBUFS;
 617                         goto error;
 618                 }
 619         }
 620
 621         /* process the next component */
 622         if (key) {
 623                 _debug("advance");
 624                 inode_unlock(d_inode(dir));
 625                 dput(dir);
 626                 dir = next;
 627                 next = NULL;
 628                 goto advance;
 629         }
 630
 631         /* we've found the object we were looking for */
 632         object->dentry = next;
 633
 634         /* if we've found that the terminal object exists, then we need to
 635          * check its attributes and delete it if it's out of date */
 636         if (!object->new) {
 637                 _debug("validate '%pd'", next);
 638
 639                 ret = cachefiles_check_object_xattr(object, auxdata);
 640                 if (ret == -ESTALE) {
 641                         /* delete the object (the deleter drops the directory
 642                          * mutex) */
 643                         object->dentry = NULL;
 644
 645                         ret = cachefiles_bury_object(cache, object, dir, next,
 646                                                      true,
 647                                                      FSCACHE_OBJECT_IS_STALE);
 648                         dput(next);
 649                         next = NULL;
 650
 651                         if (ret < 0)
 652                                 goto delete_error;
 653
 654                         _debug("redo lookup");
 655                         fscache_object_retrying_stale(&object->fscache);
 656                         goto lookup_again;
 657                 }
 658         }
 659
 660         /* note that we're now using this object */
 661         ret = cachefiles_mark_object_active(cache, object);
 662
 663         inode_unlock(d_inode(dir));
 664         dput(dir);
 665         dir = NULL;
 666
 667         if (ret == -ETIMEDOUT)
 668                 goto mark_active_timed_out;
 669
 670         _debug("=== OBTAINED_OBJECT ===");
 671
 672         if (object->new) {
 673                 /* attach data to a newly constructed terminal object */
 674                 ret = cachefiles_set_object_xattr(object, auxdata);
 675                 if (ret < 0)
 676                         goto check_error;
 677         } else {
 678                 /* always update the atime on an object we've just looked up
 679                  * (this is used to keep track of culling, and atimes are only
 680                  * updated by read, write and readdir but not lookup or
 681                  * open) */
 682                 path.dentry = next;
 683                 touch_atime(&path);
 684         }
 685
 686         /* open a file interface onto a data file */
 687         if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
 688                 if (d_is_reg(object->dentry)) {
 689                         const struct address_space_operations *aops;
 690
 691                         ret = -EPERM;
 692                         aops = d_backing_inode(object->dentry)->i_mapping->a_ops;
 693                         if (!aops->bmap)
 694                                 goto check_error;
 695                         if (object->dentry->d_sb->s_blocksize > PAGE_SIZE)
 696                                 goto check_error;
 697
 698                         object->backer = object->dentry;
 699                 } else {
 700                         BUG(); // TODO: open file in data-class subdir
 701                 }
 702         }
 703
 704         object->new = 0;
 705         fscache_obtained_object(&object->fscache);
 706
 707         _leave(" = 0 [%lu]", d_backing_inode(object->dentry)->i_ino);
 708         return 0;
 709
 710 no_space_error:
 711         fscache_object_mark_killed(&object->fscache, FSCACHE_OBJECT_NO_SPACE);
 712 create_error:
 713         _debug("create error %d", ret);
 714         if (ret == -EIO)
 715                 cachefiles_io_error(cache, "Create/mkdir failed");
 716         goto error;
 717
 718 mark_active_timed_out:
 719         _debug("mark active timed out");
 720         goto release_dentry;
 721
 722 check_error:
 723         _debug("check error %d", ret);
 724         cachefiles_mark_object_inactive(
 725                 cache, object, d_backing_inode(object->dentry)->i_blocks);
 726 release_dentry:
 727         dput(object->dentry);
 728         object->dentry = NULL;
 729         goto error_out;
 730
 731 delete_error:
 732         _debug("delete error %d", ret);
 733         goto error_out2;
 734
 735 lookup_error:
 736         _debug("lookup error %ld", PTR_ERR(next));
 737         ret = PTR_ERR(next);
 738         if (ret == -EIO)
 739                 cachefiles_io_error(cache, "Lookup failed");
 740         next = NULL;
 741 error:
 742         inode_unlock(d_inode(dir));
 743         dput(next);
 744 error_out2:
 745         dput(dir);
 746 error_out:
 747         _leave(" = error %d", -ret);
 748         return ret;
 749 }
 750
 751 /*
 752  * get a subdirectory
 753  */
 754 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
 755                                         struct dentry *dir,
 756                                         const char *dirname)
 757 {
 758         struct dentry *subdir;
 759         struct path path;
 760         int ret;
 761
 762         _enter(",,%s", dirname);
 763
 764         /* search the current directory for the element name */
 765         inode_lock(d_inode(dir));
 766
 767 retry:
 768         subdir = lookup_one_len(dirname, dir, strlen(dirname));
 769         if (IS_ERR(subdir)) {
 770                 if (PTR_ERR(subdir) == -ENOMEM)
 771                         goto nomem_d_alloc;
 772                 goto lookup_error;
 773         }
 774
 775         _debug("subdir -> %pd %s",
 776                subdir, d_backing_inode(subdir) ? "positive" : "negative");
 777
 778         /* we need to create the subdir if it doesn't exist yet */
 779         if (d_is_negative(subdir)) {
 780                 ret = cachefiles_has_space(cache, 1, 0);
 781                 if (ret < 0)
 782                         goto mkdir_error;
 783
 784                 _debug("attempt mkdir");
 785
 786                 path.mnt = cache->mnt;
 787                 path.dentry = dir;
 788                 ret = security_path_mkdir(&path, subdir, 0700);
 789                 if (ret < 0)
 790                         goto mkdir_error;
 791                 ret = vfs_mkdir(&init_user_ns, d_inode(dir), subdir, 0700);
 792                 if (ret < 0)
 793                         goto mkdir_error;
 794
 795                 if (unlikely(d_unhashed(subdir))) {
 796                         dput(subdir);
 797                         goto retry;
 798                 }
 799                 ASSERT(d_backing_inode(subdir));
 800
 801                 _debug("mkdir -> %pd{ino=%lu}",
 802                        subdir, d_backing_inode(subdir)->i_ino);
 803         }
 804
 805         inode_unlock(d_inode(dir));
 806
 807         /* we need to make sure the subdir is a directory */
 808         ASSERT(d_backing_inode(subdir));
 809
 810         if (!d_can_lookup(subdir)) {
 811                 pr_err("%s is not a directory\n", dirname);
 812                 ret = -EIO;
 813                 goto check_error;
 814         }
 815
 816         ret = -EPERM;
 817         if (!(d_backing_inode(subdir)->i_opflags & IOP_XATTR) ||
 818             !d_backing_inode(subdir)->i_op->lookup ||
 819             !d_backing_inode(subdir)->i_op->mkdir ||
 820             !d_backing_inode(subdir)->i_op->create ||
 821             !d_backing_inode(subdir)->i_op->rename ||
 822             !d_backing_inode(subdir)->i_op->rmdir ||
 823             !d_backing_inode(subdir)->i_op->unlink)
 824                 goto check_error;
 825
 826         _leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
 827         return subdir;
 828
 829 check_error:
 830         dput(subdir);
 831         _leave(" = %d [check]", ret);
 832         return ERR_PTR(ret);
 833
 834 mkdir_error:
 835         inode_unlock(d_inode(dir));
 836         dput(subdir);
 837         pr_err("mkdir %s failed with error %d\n", dirname, ret);
 838         return ERR_PTR(ret);
 839
 840 lookup_error:
 841         inode_unlock(d_inode(dir));
 842         ret = PTR_ERR(subdir);
 843         pr_err("Lookup %s failed with error %d\n", dirname, ret);
 844         return ERR_PTR(ret);
 845
 846 nomem_d_alloc:
 847         inode_unlock(d_inode(dir));
 848         _leave(" = -ENOMEM");
 849         return ERR_PTR(-ENOMEM);
 850 }
 851
 852 /*
 853  * find out if an object is in use or not
 854  * - if finds object and it's not in use:
 855  *   - returns a pointer to the object and a reference on it
 856  *   - returns with the directory locked
 857  */
 858 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
 859                                               struct dentry *dir,
 860                                               char *filename)
 861 {
 862         struct cachefiles_object *object;
 863         struct rb_node *_n;
 864         struct dentry *victim;
 865         int ret;
 866
 867         //_enter(",%pd/,%s",
 868         //       dir, filename);
 869
 870         /* look up the victim */
 871         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
 872
 873         victim = lookup_one_len(filename, dir, strlen(filename));
 874         if (IS_ERR(victim))
 875                 goto lookup_error;
 876
 877         //_debug("victim -> %pd %s",
 878         //       victim, d_backing_inode(victim) ? "positive" : "negative");
 879
 880         /* if the object is no longer there then we probably retired the object
 881          * at the netfs's request whilst the cull was in progress
 882          */
 883         if (d_is_negative(victim)) {
 884                 inode_unlock(d_inode(dir));
 885                 dput(victim);
 886                 _leave(" = -ENOENT [absent]");
 887                 return ERR_PTR(-ENOENT);
 888         }
 889
 890         /* check to see if we're using this object */
 891         read_lock(&cache->active_lock);
 892
 893         _n = cache->active_nodes.rb_node;
 894
 895         while (_n) {
 896                 object = rb_entry(_n, struct cachefiles_object, active_node);
 897
 898                 if (object->dentry > victim)
 899                         _n = _n->rb_left;
 900                 else if (object->dentry < victim)
 901                         _n = _n->rb_right;
 902                 else
 903                         goto object_in_use;
 904         }
 905
 906         read_unlock(&cache->active_lock);
 907
 908         //_leave(" = %pd", victim);
 909         return victim;
 910
 911 object_in_use:
 912         read_unlock(&cache->active_lock);
 913         inode_unlock(d_inode(dir));
 914         dput(victim);
 915         //_leave(" = -EBUSY [in use]");
 916         return ERR_PTR(-EBUSY);
 917
 918 lookup_error:
 919         inode_unlock(d_inode(dir));
 920         ret = PTR_ERR(victim);
 921         if (ret == -ENOENT) {
 922                 /* file or dir now absent - probably retired by netfs */
 923                 _leave(" = -ESTALE [absent]");
 924                 return ERR_PTR(-ESTALE);
 925         }
 926
 927         if (ret == -EIO) {
 928                 cachefiles_io_error(cache, "Lookup failed");
 929         } else if (ret != -ENOMEM) {
 930                 pr_err("Internal error: %d\n", ret);
 931                 ret = -EIO;
 932         }
 933
 934         _leave(" = %d", ret);
 935         return ERR_PTR(ret);
 936 }
 937
 938 /*
 939  * cull an object if it's not in use
 940  * - called only by cache manager daemon
 941  */
 942 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
 943                     char *filename)
 944 {
 945         struct dentry *victim;
 946         int ret;
 947
 948         _enter(",%pd/,%s", dir, filename);
 949
 950         victim = cachefiles_check_active(cache, dir, filename);
 951         if (IS_ERR(victim))
 952                 return PTR_ERR(victim);
 953
 954         _debug("victim -> %pd %s",
 955                victim, d_backing_inode(victim) ? "positive" : "negative");
 956
 957         /* okay... the victim is not being used so we can cull it
 958          * - start by marking it as stale
 959          */
 960         _debug("victim is cullable");
 961
 962         ret = cachefiles_remove_object_xattr(cache, victim);
 963         if (ret < 0)
 964                 goto error_unlock;
 965
 966         /*  actually remove the victim (drops the dir mutex) */
 967         _debug("bury");
 968
 969         ret = cachefiles_bury_object(cache, NULL, dir, victim, false,
 970                                      FSCACHE_OBJECT_WAS_CULLED);
 971         if (ret < 0)
 972                 goto error;
 973
 974         dput(victim);
 975         _leave(" = 0");
 976         return 0;
 977
 978 error_unlock:
 979         inode_unlock(d_inode(dir));
 980 error:
 981         dput(victim);
 982         if (ret == -ENOENT) {
 983                 /* file or dir now absent - probably retired by netfs */
 984                 _leave(" = -ESTALE [absent]");
 985                 return -ESTALE;
 986         }
 987
 988         if (ret != -ENOMEM) {
 989                 pr_err("Internal error: %d\n", ret);
 990                 ret = -EIO;
 991         }
 992
 993         _leave(" = %d", ret);
 994         return ret;
 995 }
 996
 997 /*
 998  * find out if an object is in use or not
 999  * - called only by cache manager daemon
1000  * - returns -EBUSY or 0 to indicate whether an object is in use or not
1001  */
1002 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
1003                             char *filename)
1004 {
1005         struct dentry *victim;
1006
1007         //_enter(",%pd/,%s",
1008         //       dir, filename);
1009
1010         victim = cachefiles_check_active(cache, dir, filename);
1011         if (IS_ERR(victim))
1012                 return PTR_ERR(victim);
1013
1014         inode_unlock(d_inode(dir));
1015         dput(victim);
1016         //_leave(" = 0");
1017         return 0;
1018 }