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 {
  34         struct fscache_cookie *cookie;
  35         const u8 *k;
  36         unsigned 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                 pr_err("%skey=[%u] '", prefix, cookie->key_len);
  59                 k = (cookie->key_len <= sizeof(cookie->inline_key)) ?
  60                         cookie->inline_key : cookie->key;
  61                 for (loop = 0; loop < cookie->key_len; loop++)
  62                         pr_cont("%02x", k[loop]);
  63                 pr_cont("'\n");
  64         } else {
  65                 pr_err("%scookie=NULL\n", prefix);
  66         }
  67         spin_unlock(&object->fscache.lock);
  68 }
  69
  70 /*
  71  * dump debugging info about a pair of objects
  72  */
  73 static noinline void cachefiles_printk_object(struct cachefiles_object *object,
  74                                               struct cachefiles_object *xobject)
  75 {
  76         if (object)
  77                 __cachefiles_printk_object(object, "");
  78         if (xobject)
  79                 __cachefiles_printk_object(xobject, "x");
  80 }
  81
  82 /*
  83  * mark the owner of a dentry, if there is one, to indicate that that dentry
  84  * has been preemptively deleted
  85  * - the caller must hold the i_mutex on the dentry's parent as required to
  86  *   call vfs_unlink(), vfs_rmdir() or vfs_rename()
  87  */
  88 static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
  89                                           struct dentry *dentry,
  90                                           enum fscache_why_object_killed why)
  91 {
  92         struct cachefiles_object *object;
  93         struct rb_node *p;
  94
  95         _enter(",'%pd'", dentry);
  96
  97         write_lock(&cache->active_lock);
  98
  99         p = cache->active_nodes.rb_node;
 100         while (p) {
 101                 object = rb_entry(p, struct cachefiles_object, active_node);
 102                 if (object->dentry > dentry)
 103                         p = p->rb_left;
 104                 else if (object->dentry < dentry)
 105                         p = p->rb_right;
 106                 else
 107                         goto found_dentry;
 108         }
 109
 110         write_unlock(&cache->active_lock);
 111         trace_cachefiles_mark_buried(NULL, dentry, why);
 112         _leave(" [no owner]");
 113         return;
 114
 115         /* found the dentry for  */
 116 found_dentry:
 117         kdebug("preemptive burial: OBJ%x [%s] %p",
 118                object->fscache.debug_id,
 119                object->fscache.state->name,
 120                dentry);
 121
 122         trace_cachefiles_mark_buried(object, dentry, why);
 123
 124         if (fscache_object_is_live(&object->fscache)) {
 125                 pr_err("\n");
 126                 pr_err("Error: Can't preemptively bury live object\n");
 127                 cachefiles_printk_object(object, NULL);
 128         } else {
 129                 if (why != FSCACHE_OBJECT_IS_STALE)
 130                         fscache_object_mark_killed(&object->fscache, why);
 131         }
 132
 133         write_unlock(&cache->active_lock);
 134         _leave(" [owner marked]");
 135 }
 136
 137 /*
 138  * record the fact that an object is now active
 139  */
 140 static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
 141                                          struct cachefiles_object *object)
 142 {
 143         struct cachefiles_object *xobject;
 144         struct rb_node **_p, *_parent = NULL;
 145         struct dentry *dentry;
 146
 147         _enter(",%p", object);
 148
 149 try_again:
 150         write_lock(&cache->active_lock);
 151
 152         dentry = object->dentry;
 153         trace_cachefiles_mark_active(object, dentry);
 154
 155         if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
 156                 pr_err("Error: Object already active\n");
 157                 cachefiles_printk_object(object, NULL);
 158                 BUG();
 159         }
 160
 161         _p = &cache->active_nodes.rb_node;
 162         while (*_p) {
 163                 _parent = *_p;
 164                 xobject = rb_entry(_parent,
 165                                    struct cachefiles_object, active_node);
 166
 167                 ASSERT(xobject != object);
 168
 169                 if (xobject->dentry > dentry)
 170                         _p = &(*_p)->rb_left;
 171                 else if (xobject->dentry < dentry)
 172                         _p = &(*_p)->rb_right;
 173                 else
 174                         goto wait_for_old_object;
 175         }
 176
 177         rb_link_node(&object->active_node, _parent, _p);
 178         rb_insert_color(&object->active_node, &cache->active_nodes);
 179
 180         write_unlock(&cache->active_lock);
 181         _leave(" = 0");
 182         return 0;
 183
 184         /* an old object from a previous incarnation is hogging the slot - we
 185          * need to wait for it to be destroyed */
 186 wait_for_old_object:
 187         trace_cachefiles_wait_active(object, dentry, xobject);
 188         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 189
 190         if (fscache_object_is_live(&xobject->fscache)) {
 191                 pr_err("\n");
 192                 pr_err("Error: Unexpected object collision\n");
 193                 cachefiles_printk_object(object, xobject);
 194         }
 195         atomic_inc(&xobject->usage);
 196         write_unlock(&cache->active_lock);
 197
 198         if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 199                 wait_queue_head_t *wq;
 200
 201                 signed long timeout = 60 * HZ;
 202                 wait_queue_entry_t wait;
 203                 bool requeue;
 204
 205                 /* if the object we're waiting for is queued for processing,
 206                  * then just put ourselves on the queue behind it */
 207                 if (work_pending(&xobject->fscache.work)) {
 208                         _debug("queue OBJ%x behind OBJ%x immediately",
 209                                object->fscache.debug_id,
 210                                xobject->fscache.debug_id);
 211                         goto requeue;
 212                 }
 213
 214                 /* otherwise we sleep until either the object we're waiting for
 215                  * is done, or the fscache_object is congested */
 216                 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
 217                 init_wait(&wait);
 218                 requeue = false;
 219                 do {
 220                         prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
 221                         if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
 222                                 break;
 223
 224                         requeue = fscache_object_sleep_till_congested(&timeout);
 225                 } while (timeout > 0 && !requeue);
 226                 finish_wait(wq, &wait);
 227
 228                 if (requeue &&
 229                     test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 230                         _debug("queue OBJ%x behind OBJ%x after wait",
 231                                object->fscache.debug_id,
 232                                xobject->fscache.debug_id);
 233                         goto requeue;
 234                 }
 235
 236                 if (timeout <= 0) {
 237                         pr_err("\n");
 238                         pr_err("Error: Overlong wait for old active object to go away\n");
 239                         cachefiles_printk_object(object, xobject);
 240                         goto requeue;
 241                 }
 242         }
 243
 244         ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
 245
 246         cache->cache.ops->put_object(&xobject->fscache,
 247                 (enum fscache_obj_ref_trace)cachefiles_obj_put_wait_retry);
 248         goto try_again;
 249
 250 requeue:
 251         cache->cache.ops->put_object(&xobject->fscache,
 252                 (enum fscache_obj_ref_trace)cachefiles_obj_put_wait_timeo);
 253         _leave(" = -ETIMEDOUT");
 254         return -ETIMEDOUT;
 255 }
 256
 257 /*
 258  * Mark an object as being inactive.
 259  */
 260 void cachefiles_mark_object_inactive(struct cachefiles_cache *cache,
 261                                      struct cachefiles_object *object,
 262                                      blkcnt_t i_blocks)
 263 {
 264         struct dentry *dentry = object->dentry;
 265         struct inode *inode = d_backing_inode(dentry);
 266
 267         trace_cachefiles_mark_inactive(object, dentry, inode);
 268
 269         write_lock(&cache->active_lock);
 270         rb_erase(&object->active_node, &cache->active_nodes);
 271         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 272         write_unlock(&cache->active_lock);
 273
 274         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
 275
 276         /* This object can now be culled, so we need to let the daemon know
 277          * that there is something it can remove if it needs to.
 278          */
 279         atomic_long_add(i_blocks, &cache->b_released);
 280         if (atomic_inc_return(&cache->f_released))
 281                 cachefiles_state_changed(cache);
 282 }
 283
 284 /*
 285  * delete an object representation from the cache
 286  * - file backed objects are unlinked
 287  * - directory backed objects are stuffed into the graveyard for userspace to
 288  *   delete
 289  * - unlocks the directory mutex
 290  */
 291 static int cachefiles_bury_object(struct cachefiles_cache *cache,
 292                                   struct cachefiles_object *object,
 293                                   struct dentry *dir,
 294                                   struct dentry *rep,
 295                                   bool preemptive,
 296                                   enum fscache_why_object_killed why)
 297 {
 298         struct dentry *grave, *trap;
 299         struct path path, path_to_graveyard;
 300         char nbuffer[8 + 8 + 1];
 301         int ret;
 302
 303         _enter(",'%pd','%pd'", dir, rep);
 304
 305         _debug("remove %p from %p", rep, dir);
 306
 307         /* non-directories can just be unlinked */
 308         if (!d_is_dir(rep)) {
 309                 _debug("unlink stale object");
 310
 311                 path.mnt = cache->mnt;
 312                 path.dentry = dir;
 313                 ret = security_path_unlink(&path, rep);
 314                 if (ret < 0) {
 315                         cachefiles_io_error(cache, "Unlink security error");
 316                 } else {
 317                         trace_cachefiles_unlink(object, rep, why);
 318                         ret = vfs_unlink(d_inode(dir), rep, NULL);
 319
 320                         if (preemptive)
 321                                 cachefiles_mark_object_buried(cache, rep, why);
 322                 }
 323
 324                 inode_unlock(d_inode(dir));
 325
 326                 if (ret == -EIO)
 327                         cachefiles_io_error(cache, "Unlink failed");
 328
 329                 _leave(" = %d", ret);
 330                 return ret;
 331         }
 332
 333         /* directories have to be moved to the graveyard */
 334         _debug("move stale object to graveyard");
 335         inode_unlock(d_inode(dir));
 336
 337 try_again:
 338         /* first step is to make up a grave dentry in the graveyard */
 339         sprintf(nbuffer, "%08x%08x",
 340                 (uint32_t) ktime_get_real_seconds(),
 341                 (uint32_t) atomic_inc_return(&cache->gravecounter));
 342
 343         /* do the multiway lock magic */
 344         trap = lock_rename(cache->graveyard, dir);
 345
 346         /* do some checks before getting the grave dentry */
 347         if (rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) {
 348                 /* the entry was probably culled when we dropped the parent dir
 349                  * lock */
 350                 unlock_rename(cache->graveyard, dir);
 351                 _leave(" = 0 [culled?]");
 352                 return 0;
 353         }
 354
 355         if (!d_can_lookup(cache->graveyard)) {
 356                 unlock_rename(cache->graveyard, dir);
 357                 cachefiles_io_error(cache, "Graveyard no longer a directory");
 358                 return -EIO;
 359         }
 360
 361         if (trap == rep) {
 362                 unlock_rename(cache->graveyard, dir);
 363                 cachefiles_io_error(cache, "May not make directory loop");
 364                 return -EIO;
 365         }
 366
 367         if (d_mountpoint(rep)) {
 368                 unlock_rename(cache->graveyard, dir);
 369                 cachefiles_io_error(cache, "Mountpoint in cache");
 370                 return -EIO;
 371         }
 372
 373         grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
 374         if (IS_ERR(grave)) {
 375                 unlock_rename(cache->graveyard, dir);
 376
 377                 if (PTR_ERR(grave) == -ENOMEM) {
 378                         _leave(" = -ENOMEM");
 379                         return -ENOMEM;
 380                 }
 381
 382                 cachefiles_io_error(cache, "Lookup error %ld",
 383                                     PTR_ERR(grave));
 384                 return -EIO;
 385         }
 386
 387         if (d_is_positive(grave)) {
 388                 unlock_rename(cache->graveyard, dir);
 389                 dput(grave);
 390                 grave = NULL;
 391                 cond_resched();
 392                 goto try_again;
 393         }
 394
 395         if (d_mountpoint(grave)) {
 396                 unlock_rename(cache->graveyard, dir);
 397                 dput(grave);
 398                 cachefiles_io_error(cache, "Mountpoint in graveyard");
 399                 return -EIO;
 400         }
 401
 402         /* target should not be an ancestor of source */
 403         if (trap == grave) {
 404                 unlock_rename(cache->graveyard, dir);
 405                 dput(grave);
 406                 cachefiles_io_error(cache, "May not make directory loop");
 407                 return -EIO;
 408         }
 409
 410         /* attempt the rename */
 411         path.mnt = cache->mnt;
 412         path.dentry = dir;
 413         path_to_graveyard.mnt = cache->mnt;
 414         path_to_graveyard.dentry = cache->graveyard;
 415         ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0);
 416         if (ret < 0) {
 417                 cachefiles_io_error(cache, "Rename security error %d", ret);
 418         } else {
 419                 trace_cachefiles_rename(object, rep, grave, why);
 420                 ret = vfs_rename(d_inode(dir), rep,
 421                                  d_inode(cache->graveyard), grave, NULL, 0);
 422                 if (ret != 0 && ret != -ENOMEM)
 423                         cachefiles_io_error(cache,
 424                                             "Rename failed with error %d", ret);
 425
 426                 if (preemptive)
 427                         cachefiles_mark_object_buried(cache, rep, why);
 428         }
 429
 430         unlock_rename(cache->graveyard, dir);
 431         dput(grave);
 432         _leave(" = 0");
 433         return 0;
 434 }
 435
 436 /*
 437  * delete an object representation from the cache
 438  */
 439 int cachefiles_delete_object(struct cachefiles_cache *cache,
 440                              struct cachefiles_object *object)
 441 {
 442         struct dentry *dir;
 443         int ret;
 444
 445         _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
 446
 447         ASSERT(object->dentry);
 448         ASSERT(d_backing_inode(object->dentry));
 449         ASSERT(object->dentry->d_parent);
 450
 451         dir = dget_parent(object->dentry);
 452
 453         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
 454
 455         if (test_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->fscache.flags)) {
 456                 /* object allocation for the same key preemptively deleted this
 457                  * object's file so that it could create its own file */
 458                 _debug("object preemptively buried");
 459                 inode_unlock(d_inode(dir));
 460                 ret = 0;
 461         } else {
 462                 /* we need to check that our parent is _still_ our parent - it
 463                  * may have been renamed */
 464                 if (dir == object->dentry->d_parent) {
 465                         ret = cachefiles_bury_object(cache, object, dir,
 466                                                      object->dentry, false,
 467                                                      FSCACHE_OBJECT_WAS_RETIRED);
 468                 } else {
 469                         /* it got moved, presumably by cachefilesd culling it,
 470                          * so it's no longer in the key path and we can ignore
 471                          * it */
 472                         inode_unlock(d_inode(dir));
 473                         ret = 0;
 474                 }
 475         }
 476
 477         dput(dir);
 478         _leave(" = %d", ret);
 479         return ret;
 480 }
 481
 482 /*
 483  * walk from the parent object to the child object through the backing
 484  * filesystem, creating directories as we go
 485  */
 486 int cachefiles_walk_to_object(struct cachefiles_object *parent,
 487                               struct cachefiles_object *object,
 488                               const char *key,
 489                               struct cachefiles_xattr *auxdata)
 490 {
 491         struct cachefiles_cache *cache;
 492         struct dentry *dir, *next = NULL;
 493         struct inode *inode;
 494         struct path path;
 495         unsigned long start;
 496         const char *name;
 497         int ret, nlen;
 498
 499         _enter("OBJ%x{%p},OBJ%x,%s,",
 500                parent->fscache.debug_id, parent->dentry,
 501                object->fscache.debug_id, key);
 502
 503         cache = container_of(parent->fscache.cache,
 504                              struct cachefiles_cache, cache);
 505         path.mnt = cache->mnt;
 506
 507         ASSERT(parent->dentry);
 508         ASSERT(d_backing_inode(parent->dentry));
 509
 510         if (!(d_is_dir(parent->dentry))) {
 511                 // TODO: convert file to dir
 512                 _leave("looking up in none directory");
 513                 return -ENOBUFS;
 514         }
 515
 516         dir = dget(parent->dentry);
 517
 518 advance:
 519         /* attempt to transit the first directory component */
 520         name = key;
 521         nlen = strlen(key);
 522
 523         /* key ends in a double NUL */
 524         key = key + nlen + 1;
 525         if (!*key)
 526                 key = NULL;
 527
 528 lookup_again:
 529         /* search the current directory for the element name */
 530         _debug("lookup '%s'", name);
 531
 532         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
 533
 534         start = jiffies;
 535         next = lookup_one_len(name, dir, nlen);
 536         cachefiles_hist(cachefiles_lookup_histogram, start);
 537         if (IS_ERR(next)) {
 538                 trace_cachefiles_lookup(object, next, NULL);
 539                 goto lookup_error;
 540         }
 541
 542         inode = d_backing_inode(next);
 543         trace_cachefiles_lookup(object, next, inode);
 544         _debug("next -> %p %s", next, inode ? "positive" : "negative");
 545
 546         if (!key)
 547                 object->new = !inode;
 548
 549         /* if this element of the path doesn't exist, then the lookup phase
 550          * failed, and we can release any readers in the certain knowledge that
 551          * there's nothing for them to actually read */
 552         if (d_is_negative(next))
 553                 fscache_object_lookup_negative(&object->fscache);
 554
 555         /* we need to create the object if it's negative */
 556         if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
 557                 /* index objects and intervening tree levels must be subdirs */
 558                 if (d_is_negative(next)) {
 559                         ret = cachefiles_has_space(cache, 1, 0);
 560                         if (ret < 0)
 561                                 goto no_space_error;
 562
 563                         path.dentry = dir;
 564                         ret = security_path_mkdir(&path, next, 0);
 565                         if (ret < 0)
 566                                 goto create_error;
 567                         start = jiffies;
 568                         ret = vfs_mkdir(d_inode(dir), next, 0);
 569                         cachefiles_hist(cachefiles_mkdir_histogram, start);
 570                         if (!key)
 571                                 trace_cachefiles_mkdir(object, next, ret);
 572                         if (ret < 0)
 573                                 goto create_error;
 574
 575                         if (unlikely(d_unhashed(next))) {
 576                                 dput(next);
 577                                 inode_unlock(d_inode(dir));
 578                                 goto lookup_again;
 579                         }
 580                         ASSERT(d_backing_inode(next));
 581
 582                         _debug("mkdir -> %p{%p{ino=%lu}}",
 583                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
 584
 585                 } else if (!d_can_lookup(next)) {
 586                         pr_err("inode %lu is not a directory\n",
 587                                d_backing_inode(next)->i_ino);
 588                         ret = -ENOBUFS;
 589                         goto error;
 590                 }
 591
 592         } else {
 593                 /* non-index objects start out life as files */
 594                 if (d_is_negative(next)) {
 595                         ret = cachefiles_has_space(cache, 1, 0);
 596                         if (ret < 0)
 597                                 goto no_space_error;
 598
 599                         path.dentry = dir;
 600                         ret = security_path_mknod(&path, next, S_IFREG, 0);
 601                         if (ret < 0)
 602                                 goto create_error;
 603                         start = jiffies;
 604                         ret = vfs_create(d_inode(dir), next, S_IFREG, true);
 605                         cachefiles_hist(cachefiles_create_histogram, start);
 606                         trace_cachefiles_create(object, next, ret);
 607                         if (ret < 0)
 608                                 goto create_error;
 609
 610                         ASSERT(d_backing_inode(next));
 611
 612                         _debug("create -> %p{%p{ino=%lu}}",
 613                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
 614
 615                 } else if (!d_can_lookup(next) &&
 616                            !d_is_reg(next)
 617                            ) {
 618                         pr_err("inode %lu is not a file or directory\n",
 619                                d_backing_inode(next)->i_ino);
 620                         ret = -ENOBUFS;
 621                         goto error;
 622                 }
 623         }
 624
 625         /* process the next component */
 626         if (key) {
 627                 _debug("advance");
 628                 inode_unlock(d_inode(dir));
 629                 dput(dir);
 630                 dir = next;
 631                 next = NULL;
 632                 goto advance;
 633         }
 634
 635         /* we've found the object we were looking for */
 636         object->dentry = next;
 637
 638         /* if we've found that the terminal object exists, then we need to
 639          * check its attributes and delete it if it's out of date */
 640         if (!object->new) {
 641                 _debug("validate '%pd'", next);
 642
 643                 ret = cachefiles_check_object_xattr(object, auxdata);
 644                 if (ret == -ESTALE) {
 645                         /* delete the object (the deleter drops the directory
 646                          * mutex) */
 647                         object->dentry = NULL;
 648
 649                         ret = cachefiles_bury_object(cache, object, dir, next,
 650                                                      true,
 651                                                      FSCACHE_OBJECT_IS_STALE);
 652                         dput(next);
 653                         next = NULL;
 654
 655                         if (ret < 0)
 656                                 goto delete_error;
 657
 658                         _debug("redo lookup");
 659                         fscache_object_retrying_stale(&object->fscache);
 660                         goto lookup_again;
 661                 }
 662         }
 663
 664         /* note that we're now using this object */
 665         ret = cachefiles_mark_object_active(cache, object);
 666
 667         inode_unlock(d_inode(dir));
 668         dput(dir);
 669         dir = NULL;
 670
 671         if (ret == -ETIMEDOUT)
 672                 goto mark_active_timed_out;
 673
 674         _debug("=== OBTAINED_OBJECT ===");
 675
 676         if (object->new) {
 677                 /* attach data to a newly constructed terminal object */
 678                 ret = cachefiles_set_object_xattr(object, auxdata);
 679                 if (ret < 0)
 680                         goto check_error;
 681         } else {
 682                 /* always update the atime on an object we've just looked up
 683                  * (this is used to keep track of culling, and atimes are only
 684                  * updated by read, write and readdir but not lookup or
 685                  * open) */
 686                 path.dentry = next;
 687                 touch_atime(&path);
 688         }
 689
 690         /* open a file interface onto a data file */
 691         if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
 692                 if (d_is_reg(object->dentry)) {
 693                         const struct address_space_operations *aops;
 694
 695                         ret = -EPERM;
 696                         aops = d_backing_inode(object->dentry)->i_mapping->a_ops;
 697                         if (!aops->bmap)
 698                                 goto check_error;
 699                         if (object->dentry->d_sb->s_blocksize > PAGE_SIZE)
 700                                 goto check_error;
 701
 702                         object->backer = object->dentry;
 703                 } else {
 704                         BUG(); // TODO: open file in data-class subdir
 705                 }
 706         }
 707
 708         object->new = 0;
 709         fscache_obtained_object(&object->fscache);
 710
 711         _leave(" = 0 [%lu]", d_backing_inode(object->dentry)->i_ino);
 712         return 0;
 713
 714 no_space_error:
 715         fscache_object_mark_killed(&object->fscache, FSCACHE_OBJECT_NO_SPACE);
 716 create_error:
 717         _debug("create error %d", ret);
 718         if (ret == -EIO)
 719                 cachefiles_io_error(cache, "Create/mkdir failed");
 720         goto error;
 721
 722 mark_active_timed_out:
 723         _debug("mark active timed out");
 724         goto release_dentry;
 725
 726 check_error:
 727         _debug("check error %d", ret);
 728         cachefiles_mark_object_inactive(
 729                 cache, object, d_backing_inode(object->dentry)->i_blocks);
 730 release_dentry:
 731         dput(object->dentry);
 732         object->dentry = NULL;
 733         goto error_out;
 734
 735 delete_error:
 736         _debug("delete error %d", ret);
 737         goto error_out2;
 738
 739 lookup_error:
 740         _debug("lookup error %ld", PTR_ERR(next));
 741         ret = PTR_ERR(next);
 742         if (ret == -EIO)
 743                 cachefiles_io_error(cache, "Lookup failed");
 744         next = NULL;
 745 error:
 746         inode_unlock(d_inode(dir));
 747         dput(next);
 748 error_out2:
 749         dput(dir);
 750 error_out:
 751         _leave(" = error %d", -ret);
 752         return ret;
 753 }
 754
 755 /*
 756  * get a subdirectory
 757  */
 758 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
 759                                         struct dentry *dir,
 760                                         const char *dirname)
 761 {
 762         struct dentry *subdir;
 763         unsigned long start;
 764         struct path path;
 765         int ret;
 766
 767         _enter(",,%s", dirname);
 768
 769         /* search the current directory for the element name */
 770         inode_lock(d_inode(dir));
 771
 772 retry:
 773         start = jiffies;
 774         subdir = lookup_one_len(dirname, dir, strlen(dirname));
 775         cachefiles_hist(cachefiles_lookup_histogram, start);
 776         if (IS_ERR(subdir)) {
 777                 if (PTR_ERR(subdir) == -ENOMEM)
 778                         goto nomem_d_alloc;
 779                 goto lookup_error;
 780         }
 781
 782         _debug("subdir -> %p %s",
 783                subdir, d_backing_inode(subdir) ? "positive" : "negative");
 784
 785         /* we need to create the subdir if it doesn't exist yet */
 786         if (d_is_negative(subdir)) {
 787                 ret = cachefiles_has_space(cache, 1, 0);
 788                 if (ret < 0)
 789                         goto mkdir_error;
 790
 791                 _debug("attempt mkdir");
 792
 793                 path.mnt = cache->mnt;
 794                 path.dentry = dir;
 795                 ret = security_path_mkdir(&path, subdir, 0700);
 796                 if (ret < 0)
 797                         goto mkdir_error;
 798                 ret = vfs_mkdir(d_inode(dir), subdir, 0700);
 799                 if (ret < 0)
 800                         goto mkdir_error;
 801
 802                 if (unlikely(d_unhashed(subdir))) {
 803                         dput(subdir);
 804                         goto retry;
 805                 }
 806                 ASSERT(d_backing_inode(subdir));
 807
 808                 _debug("mkdir -> %p{%p{ino=%lu}}",
 809                        subdir,
 810                        d_backing_inode(subdir),
 811                        d_backing_inode(subdir)->i_ino);
 812         }
 813
 814         inode_unlock(d_inode(dir));
 815
 816         /* we need to make sure the subdir is a directory */
 817         ASSERT(d_backing_inode(subdir));
 818
 819         if (!d_can_lookup(subdir)) {
 820                 pr_err("%s is not a directory\n", dirname);
 821                 ret = -EIO;
 822                 goto check_error;
 823         }
 824
 825         ret = -EPERM;
 826         if (!(d_backing_inode(subdir)->i_opflags & IOP_XATTR) ||
 827             !d_backing_inode(subdir)->i_op->lookup ||
 828             !d_backing_inode(subdir)->i_op->mkdir ||
 829             !d_backing_inode(subdir)->i_op->create ||
 830             !d_backing_inode(subdir)->i_op->rename ||
 831             !d_backing_inode(subdir)->i_op->rmdir ||
 832             !d_backing_inode(subdir)->i_op->unlink)
 833                 goto check_error;
 834
 835         _leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
 836         return subdir;
 837
 838 check_error:
 839         dput(subdir);
 840         _leave(" = %d [check]", ret);
 841         return ERR_PTR(ret);
 842
 843 mkdir_error:
 844         inode_unlock(d_inode(dir));
 845         dput(subdir);
 846         pr_err("mkdir %s failed with error %d\n", dirname, ret);
 847         return ERR_PTR(ret);
 848
 849 lookup_error:
 850         inode_unlock(d_inode(dir));
 851         ret = PTR_ERR(subdir);
 852         pr_err("Lookup %s failed with error %d\n", dirname, ret);
 853         return ERR_PTR(ret);
 854
 855 nomem_d_alloc:
 856         inode_unlock(d_inode(dir));
 857         _leave(" = -ENOMEM");
 858         return ERR_PTR(-ENOMEM);
 859 }
 860
 861 /*
 862  * find out if an object is in use or not
 863  * - if finds object and it's not in use:
 864  *   - returns a pointer to the object and a reference on it
 865  *   - returns with the directory locked
 866  */
 867 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
 868                                               struct dentry *dir,
 869                                               char *filename)
 870 {
 871         struct cachefiles_object *object;
 872         struct rb_node *_n;
 873         struct dentry *victim;
 874         unsigned long start;
 875         int ret;
 876
 877         //_enter(",%pd/,%s",
 878         //       dir, filename);
 879
 880         /* look up the victim */
 881         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
 882
 883         start = jiffies;
 884         victim = lookup_one_len(filename, dir, strlen(filename));
 885         cachefiles_hist(cachefiles_lookup_histogram, start);
 886         if (IS_ERR(victim))
 887                 goto lookup_error;
 888
 889         //_debug("victim -> %p %s",
 890         //       victim, d_backing_inode(victim) ? "positive" : "negative");
 891
 892         /* if the object is no longer there then we probably retired the object
 893          * at the netfs's request whilst the cull was in progress
 894          */
 895         if (d_is_negative(victim)) {
 896                 inode_unlock(d_inode(dir));
 897                 dput(victim);
 898                 _leave(" = -ENOENT [absent]");
 899                 return ERR_PTR(-ENOENT);
 900         }
 901
 902         /* check to see if we're using this object */
 903         read_lock(&cache->active_lock);
 904
 905         _n = cache->active_nodes.rb_node;
 906
 907         while (_n) {
 908                 object = rb_entry(_n, struct cachefiles_object, active_node);
 909
 910                 if (object->dentry > victim)
 911                         _n = _n->rb_left;
 912                 else if (object->dentry < victim)
 913                         _n = _n->rb_right;
 914                 else
 915                         goto object_in_use;
 916         }
 917
 918         read_unlock(&cache->active_lock);
 919
 920         //_leave(" = %p", victim);
 921         return victim;
 922
 923 object_in_use:
 924         read_unlock(&cache->active_lock);
 925         inode_unlock(d_inode(dir));
 926         dput(victim);
 927         //_leave(" = -EBUSY [in use]");
 928         return ERR_PTR(-EBUSY);
 929
 930 lookup_error:
 931         inode_unlock(d_inode(dir));
 932         ret = PTR_ERR(victim);
 933         if (ret == -ENOENT) {
 934                 /* file or dir now absent - probably retired by netfs */
 935                 _leave(" = -ESTALE [absent]");
 936                 return ERR_PTR(-ESTALE);
 937         }
 938
 939         if (ret == -EIO) {
 940                 cachefiles_io_error(cache, "Lookup failed");
 941         } else if (ret != -ENOMEM) {
 942                 pr_err("Internal error: %d\n", ret);
 943                 ret = -EIO;
 944         }
 945
 946         _leave(" = %d", ret);
 947         return ERR_PTR(ret);
 948 }
 949
 950 /*
 951  * cull an object if it's not in use
 952  * - called only by cache manager daemon
 953  */
 954 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
 955                     char *filename)
 956 {
 957         struct dentry *victim;
 958         int ret;
 959
 960         _enter(",%pd/,%s", dir, filename);
 961
 962         victim = cachefiles_check_active(cache, dir, filename);
 963         if (IS_ERR(victim))
 964                 return PTR_ERR(victim);
 965
 966         _debug("victim -> %p %s",
 967                victim, d_backing_inode(victim) ? "positive" : "negative");
 968
 969         /* okay... the victim is not being used so we can cull it
 970          * - start by marking it as stale
 971          */
 972         _debug("victim is cullable");
 973
 974         ret = cachefiles_remove_object_xattr(cache, victim);
 975         if (ret < 0)
 976                 goto error_unlock;
 977
 978         /*  actually remove the victim (drops the dir mutex) */
 979         _debug("bury");
 980
 981         ret = cachefiles_bury_object(cache, NULL, dir, victim, false,
 982                                      FSCACHE_OBJECT_WAS_CULLED);
 983         if (ret < 0)
 984                 goto error;
 985
 986         dput(victim);
 987         _leave(" = 0");
 988         return 0;
 989
 990 error_unlock:
 991         inode_unlock(d_inode(dir));
 992 error:
 993         dput(victim);
 994         if (ret == -ENOENT) {
 995                 /* file or dir now absent - probably retired by netfs */
 996                 _leave(" = -ESTALE [absent]");
 997                 return -ESTALE;
 998         }
 999
1000         if (ret != -ENOMEM) {
1001                 pr_err("Internal error: %d\n", ret);
1002                 ret = -EIO;
1003         }
1004
1005         _leave(" = %d", ret);
1006         return ret;
1007 }
1008
1009 /*
1010  * find out if an object is in use or not
1011  * - called only by cache manager daemon
1012  * - returns -EBUSY or 0 to indicate whether an object is in use or not
1013  */
1014 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
1015                             char *filename)
1016 {
1017         struct dentry *victim;
1018
1019         //_enter(",%pd/,%s",
1020         //       dir, filename);
1021
1022         victim = cachefiles_check_active(cache, dir, filename);
1023         if (IS_ERR(victim))
1024                 return PTR_ERR(victim);
1025
1026         inode_unlock(d_inode(dir));
1027         dput(victim);
1028         //_leave(" = 0");
1029         return 0;
1030 }