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,
 248                 (enum fscache_obj_ref_trace)cachefiles_obj_put_wait_retry);
 249         goto try_again;
 250
 251 requeue:
 252         cache->cache.ops->put_object(&xobject->fscache,
 253                 (enum fscache_obj_ref_trace)cachefiles_obj_put_wait_timeo);
 254         _leave(" = -ETIMEDOUT");
 255         return -ETIMEDOUT;
 256 }
 257
 258 /*
 259  * Mark an object as being inactive.
 260  */
 261 void cachefiles_mark_object_inactive(struct cachefiles_cache *cache,
 262                                      struct cachefiles_object *object,
 263                                      blkcnt_t i_blocks)
 264 {
 265         struct dentry *dentry = object->dentry;
 266         struct inode *inode = d_backing_inode(dentry);
 267
 268         trace_cachefiles_mark_inactive(object, dentry, inode);
 269
 270         write_lock(&cache->active_lock);
 271         rb_erase(&object->active_node, &cache->active_nodes);
 272         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 273         write_unlock(&cache->active_lock);
 274
 275         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
 276
 277         /* This object can now be culled, so we need to let the daemon know
 278          * that there is something it can remove if it needs to.
 279          */
 280         atomic_long_add(i_blocks, &cache->b_released);
 281         if (atomic_inc_return(&cache->f_released))
 282                 cachefiles_state_changed(cache);
 283 }
 284
 285 /*
 286  * delete an object representation from the cache
 287  * - file backed objects are unlinked
 288  * - directory backed objects are stuffed into the graveyard for userspace to
 289  *   delete
 290  * - unlocks the directory mutex
 291  */
 292 static int cachefiles_bury_object(struct cachefiles_cache *cache,
 293                                   struct cachefiles_object *object,
 294                                   struct dentry *dir,
 295                                   struct dentry *rep,
 296                                   bool preemptive,
 297                                   enum fscache_why_object_killed why)
 298 {
 299         struct dentry *grave, *trap;
 300         struct path path, path_to_graveyard;
 301         char nbuffer[8 + 8 + 1];
 302         int ret;
 303
 304         _enter(",'%pd','%pd'", dir, rep);
 305
 306         _debug("remove %p from %p", rep, dir);
 307
 308         /* non-directories can just be unlinked */
 309         if (!d_is_dir(rep)) {
 310                 _debug("unlink stale object");
 311
 312                 path.mnt = cache->mnt;
 313                 path.dentry = dir;
 314                 ret = security_path_unlink(&path, rep);
 315                 if (ret < 0) {
 316                         cachefiles_io_error(cache, "Unlink security error");
 317                 } else {
 318                         trace_cachefiles_unlink(object, rep, why);
 319                         ret = vfs_unlink(d_inode(dir), rep, NULL);
 320
 321                         if (preemptive)
 322                                 cachefiles_mark_object_buried(cache, rep, why);
 323                 }
 324
 325                 inode_unlock(d_inode(dir));
 326
 327                 if (ret == -EIO)
 328                         cachefiles_io_error(cache, "Unlink failed");
 329
 330                 _leave(" = %d", ret);
 331                 return ret;
 332         }
 333
 334         /* directories have to be moved to the graveyard */
 335         _debug("move stale object to graveyard");
 336         inode_unlock(d_inode(dir));
 337
 338 try_again:
 339         /* first step is to make up a grave dentry in the graveyard */
 340         sprintf(nbuffer, "%08x%08x",
 341                 (uint32_t) ktime_get_real_seconds(),
 342                 (uint32_t) atomic_inc_return(&cache->gravecounter));
 343
 344         /* do the multiway lock magic */
 345         trap = lock_rename(cache->graveyard, dir);
 346
 347         /* do some checks before getting the grave dentry */
 348         if (rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) {
 349                 /* the entry was probably culled when we dropped the parent dir
 350                  * lock */
 351                 unlock_rename(cache->graveyard, dir);
 352                 _leave(" = 0 [culled?]");
 353                 return 0;
 354         }
 355
 356         if (!d_can_lookup(cache->graveyard)) {
 357                 unlock_rename(cache->graveyard, dir);
 358                 cachefiles_io_error(cache, "Graveyard no longer a directory");
 359                 return -EIO;
 360         }
 361
 362         if (trap == rep) {
 363                 unlock_rename(cache->graveyard, dir);
 364                 cachefiles_io_error(cache, "May not make directory loop");
 365                 return -EIO;
 366         }
 367
 368         if (d_mountpoint(rep)) {
 369                 unlock_rename(cache->graveyard, dir);
 370                 cachefiles_io_error(cache, "Mountpoint in cache");
 371                 return -EIO;
 372         }
 373
 374         grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
 375         if (IS_ERR(grave)) {
 376                 unlock_rename(cache->graveyard, dir);
 377
 378                 if (PTR_ERR(grave) == -ENOMEM) {
 379                         _leave(" = -ENOMEM");
 380                         return -ENOMEM;
 381                 }
 382
 383                 cachefiles_io_error(cache, "Lookup error %ld",
 384                                     PTR_ERR(grave));
 385                 return -EIO;
 386         }
 387
 388         if (d_is_positive(grave)) {
 389                 unlock_rename(cache->graveyard, dir);
 390                 dput(grave);
 391                 grave = NULL;
 392                 cond_resched();
 393                 goto try_again;
 394         }
 395
 396         if (d_mountpoint(grave)) {
 397                 unlock_rename(cache->graveyard, dir);
 398                 dput(grave);
 399                 cachefiles_io_error(cache, "Mountpoint in graveyard");
 400                 return -EIO;
 401         }
 402
 403         /* target should not be an ancestor of source */
 404         if (trap == grave) {
 405                 unlock_rename(cache->graveyard, dir);
 406                 dput(grave);
 407                 cachefiles_io_error(cache, "May not make directory loop");
 408                 return -EIO;
 409         }
 410
 411         /* attempt the rename */
 412         path.mnt = cache->mnt;
 413         path.dentry = dir;
 414         path_to_graveyard.mnt = cache->mnt;
 415         path_to_graveyard.dentry = cache->graveyard;
 416         ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0);
 417         if (ret < 0) {
 418                 cachefiles_io_error(cache, "Rename security error %d", ret);
 419         } else {
 420                 trace_cachefiles_rename(object, rep, grave, why);
 421                 ret = vfs_rename(d_inode(dir), rep,
 422                                  d_inode(cache->graveyard), grave, NULL, 0);
 423                 if (ret != 0 && ret != -ENOMEM)
 424                         cachefiles_io_error(cache,
 425                                             "Rename failed with error %d", ret);
 426
 427                 if (preemptive)
 428                         cachefiles_mark_object_buried(cache, rep, why);
 429         }
 430
 431         unlock_rename(cache->graveyard, dir);
 432         dput(grave);
 433         _leave(" = 0");
 434         return 0;
 435 }
 436
 437 /*
 438  * delete an object representation from the cache
 439  */
 440 int cachefiles_delete_object(struct cachefiles_cache *cache,
 441                              struct cachefiles_object *object)
 442 {
 443         struct dentry *dir;
 444         int ret;
 445
 446         _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
 447
 448         ASSERT(object->dentry);
 449         ASSERT(d_backing_inode(object->dentry));
 450         ASSERT(object->dentry->d_parent);
 451
 452         dir = dget_parent(object->dentry);
 453
 454         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
 455
 456         if (test_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->fscache.flags)) {
 457                 /* object allocation for the same key preemptively deleted this
 458                  * object's file so that it could create its own file */
 459                 _debug("object preemptively buried");
 460                 inode_unlock(d_inode(dir));
 461                 ret = 0;
 462         } else {
 463                 /* we need to check that our parent is _still_ our parent - it
 464                  * may have been renamed */
 465                 if (dir == object->dentry->d_parent) {
 466                         ret = cachefiles_bury_object(cache, object, dir,
 467                                                      object->dentry, false,
 468                                                      FSCACHE_OBJECT_WAS_RETIRED);
 469                 } else {
 470                         /* it got moved, presumably by cachefilesd culling it,
 471                          * so it's no longer in the key path and we can ignore
 472                          * it */
 473                         inode_unlock(d_inode(dir));
 474                         ret = 0;
 475                 }
 476         }
 477
 478         dput(dir);
 479         _leave(" = %d", ret);
 480         return ret;
 481 }
 482
 483 /*
 484  * walk from the parent object to the child object through the backing
 485  * filesystem, creating directories as we go
 486  */
 487 int cachefiles_walk_to_object(struct cachefiles_object *parent,
 488                               struct cachefiles_object *object,
 489                               const char *key,
 490                               struct cachefiles_xattr *auxdata)
 491 {
 492         struct cachefiles_cache *cache;
 493         struct dentry *dir, *next = NULL;
 494         struct inode *inode;
 495         struct path path;
 496         unsigned long start;
 497         const char *name;
 498         int ret, nlen;
 499
 500         _enter("OBJ%x{%p},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         start = jiffies;
 536         next = lookup_one_len(name, dir, nlen);
 537         cachefiles_hist(cachefiles_lookup_histogram, start);
 538         if (IS_ERR(next)) {
 539                 trace_cachefiles_lookup(object, next, NULL);
 540                 goto lookup_error;
 541         }
 542
 543         inode = d_backing_inode(next);
 544         trace_cachefiles_lookup(object, next, inode);
 545         _debug("next -> %p %s", next, inode ? "positive" : "negative");
 546
 547         if (!key)
 548                 object->new = !inode;
 549
 550         /* if this element of the path doesn't exist, then the lookup phase
 551          * failed, and we can release any readers in the certain knowledge that
 552          * there's nothing for them to actually read */
 553         if (d_is_negative(next))
 554                 fscache_object_lookup_negative(&object->fscache);
 555
 556         /* we need to create the object if it's negative */
 557         if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
 558                 /* index objects and intervening tree levels must be subdirs */
 559                 if (d_is_negative(next)) {
 560                         ret = cachefiles_has_space(cache, 1, 0);
 561                         if (ret < 0)
 562                                 goto no_space_error;
 563
 564                         path.dentry = dir;
 565                         ret = security_path_mkdir(&path, next, 0);
 566                         if (ret < 0)
 567                                 goto create_error;
 568                         start = jiffies;
 569                         ret = vfs_mkdir(d_inode(dir), next, 0);
 570                         cachefiles_hist(cachefiles_mkdir_histogram, start);
 571                         if (!key)
 572                                 trace_cachefiles_mkdir(object, next, ret);
 573                         if (ret < 0)
 574                                 goto create_error;
 575
 576                         if (unlikely(d_unhashed(next))) {
 577                                 dput(next);
 578                                 inode_unlock(d_inode(dir));
 579                                 goto lookup_again;
 580                         }
 581                         ASSERT(d_backing_inode(next));
 582
 583                         _debug("mkdir -> %p{%p{ino=%lu}}",
 584                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
 585
 586                 } else if (!d_can_lookup(next)) {
 587                         pr_err("inode %lu is not a directory\n",
 588                                d_backing_inode(next)->i_ino);
 589                         ret = -ENOBUFS;
 590                         goto error;
 591                 }
 592
 593         } else {
 594                 /* non-index objects start out life as files */
 595                 if (d_is_negative(next)) {
 596                         ret = cachefiles_has_space(cache, 1, 0);
 597                         if (ret < 0)
 598                                 goto no_space_error;
 599
 600                         path.dentry = dir;
 601                         ret = security_path_mknod(&path, next, S_IFREG, 0);
 602                         if (ret < 0)
 603                                 goto create_error;
 604                         start = jiffies;
 605                         ret = vfs_create(d_inode(dir), next, S_IFREG, true);
 606                         cachefiles_hist(cachefiles_create_histogram, start);
 607                         trace_cachefiles_create(object, next, ret);
 608                         if (ret < 0)
 609                                 goto create_error;
 610
 611                         ASSERT(d_backing_inode(next));
 612
 613                         _debug("create -> %p{%p{ino=%lu}}",
 614                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
 615
 616                 } else if (!d_can_lookup(next) &&
 617                            !d_is_reg(next)
 618                            ) {
 619                         pr_err("inode %lu is not a file or directory\n",
 620                                d_backing_inode(next)->i_ino);
 621                         ret = -ENOBUFS;
 622                         goto error;
 623                 }
 624         }
 625
 626         /* process the next component */
 627         if (key) {
 628                 _debug("advance");
 629                 inode_unlock(d_inode(dir));
 630                 dput(dir);
 631                 dir = next;
 632                 next = NULL;
 633                 goto advance;
 634         }
 635
 636         /* we've found the object we were looking for */
 637         object->dentry = next;
 638
 639         /* if we've found that the terminal object exists, then we need to
 640          * check its attributes and delete it if it's out of date */
 641         if (!object->new) {
 642                 _debug("validate '%pd'", next);
 643
 644                 ret = cachefiles_check_object_xattr(object, auxdata);
 645                 if (ret == -ESTALE) {
 646                         /* delete the object (the deleter drops the directory
 647                          * mutex) */
 648                         object->dentry = NULL;
 649
 650                         ret = cachefiles_bury_object(cache, object, dir, next,
 651                                                      true,
 652                                                      FSCACHE_OBJECT_IS_STALE);
 653                         dput(next);
 654                         next = NULL;
 655
 656                         if (ret < 0)
 657                                 goto delete_error;
 658
 659                         _debug("redo lookup");
 660                         fscache_object_retrying_stale(&object->fscache);
 661                         goto lookup_again;
 662                 }
 663         }
 664
 665         /* note that we're now using this object */
 666         ret = cachefiles_mark_object_active(cache, object);
 667
 668         inode_unlock(d_inode(dir));
 669         dput(dir);
 670         dir = NULL;
 671
 672         if (ret == -ETIMEDOUT)
 673                 goto mark_active_timed_out;
 674
 675         _debug("=== OBTAINED_OBJECT ===");
 676
 677         if (object->new) {
 678                 /* attach data to a newly constructed terminal object */
 679                 ret = cachefiles_set_object_xattr(object, auxdata);
 680                 if (ret < 0)
 681                         goto check_error;
 682         } else {
 683                 /* always update the atime on an object we've just looked up
 684                  * (this is used to keep track of culling, and atimes are only
 685                  * updated by read, write and readdir but not lookup or
 686                  * open) */
 687                 path.dentry = next;
 688                 touch_atime(&path);
 689         }
 690
 691         /* open a file interface onto a data file */
 692         if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
 693                 if (d_is_reg(object->dentry)) {
 694                         const struct address_space_operations *aops;
 695
 696                         ret = -EPERM;
 697                         aops = d_backing_inode(object->dentry)->i_mapping->a_ops;
 698                         if (!aops->bmap)
 699                                 goto check_error;
 700                         if (object->dentry->d_sb->s_blocksize > PAGE_SIZE)
 701                                 goto check_error;
 702
 703                         object->backer = object->dentry;
 704                 } else {
 705                         BUG(); // TODO: open file in data-class subdir
 706                 }
 707         }
 708
 709         object->new = 0;
 710         fscache_obtained_object(&object->fscache);
 711
 712         _leave(" = 0 [%lu]", d_backing_inode(object->dentry)->i_ino);
 713         return 0;
 714
 715 no_space_error:
 716         fscache_object_mark_killed(&object->fscache, FSCACHE_OBJECT_NO_SPACE);
 717 create_error:
 718         _debug("create error %d", ret);
 719         if (ret == -EIO)
 720                 cachefiles_io_error(cache, "Create/mkdir failed");
 721         goto error;
 722
 723 mark_active_timed_out:
 724         _debug("mark active timed out");
 725         goto release_dentry;
 726
 727 check_error:
 728         _debug("check error %d", ret);
 729         cachefiles_mark_object_inactive(
 730                 cache, object, d_backing_inode(object->dentry)->i_blocks);
 731 release_dentry:
 732         dput(object->dentry);
 733         object->dentry = NULL;
 734         goto error_out;
 735
 736 delete_error:
 737         _debug("delete error %d", ret);
 738         goto error_out2;
 739
 740 lookup_error:
 741         _debug("lookup error %ld", PTR_ERR(next));
 742         ret = PTR_ERR(next);
 743         if (ret == -EIO)
 744                 cachefiles_io_error(cache, "Lookup failed");
 745         next = NULL;
 746 error:
 747         inode_unlock(d_inode(dir));
 748         dput(next);
 749 error_out2:
 750         dput(dir);
 751 error_out:
 752         _leave(" = error %d", -ret);
 753         return ret;
 754 }
 755
 756 /*
 757  * get a subdirectory
 758  */
 759 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
 760                                         struct dentry *dir,
 761                                         const char *dirname)
 762 {
 763         struct dentry *subdir;
 764         unsigned long start;
 765         struct path path;
 766         int ret;
 767
 768         _enter(",,%s", dirname);
 769
 770         /* search the current directory for the element name */
 771         inode_lock(d_inode(dir));
 772
 773 retry:
 774         start = jiffies;
 775         subdir = lookup_one_len(dirname, dir, strlen(dirname));
 776         cachefiles_hist(cachefiles_lookup_histogram, start);
 777         if (IS_ERR(subdir)) {
 778                 if (PTR_ERR(subdir) == -ENOMEM)
 779                         goto nomem_d_alloc;
 780                 goto lookup_error;
 781         }
 782
 783         _debug("subdir -> %p %s",
 784                subdir, d_backing_inode(subdir) ? "positive" : "negative");
 785
 786         /* we need to create the subdir if it doesn't exist yet */
 787         if (d_is_negative(subdir)) {
 788                 ret = cachefiles_has_space(cache, 1, 0);
 789                 if (ret < 0)
 790                         goto mkdir_error;
 791
 792                 _debug("attempt mkdir");
 793
 794                 path.mnt = cache->mnt;
 795                 path.dentry = dir;
 796                 ret = security_path_mkdir(&path, subdir, 0700);
 797                 if (ret < 0)
 798                         goto mkdir_error;
 799                 ret = vfs_mkdir(d_inode(dir), subdir, 0700);
 800                 if (ret < 0)
 801                         goto mkdir_error;
 802
 803                 if (unlikely(d_unhashed(subdir))) {
 804                         dput(subdir);
 805                         goto retry;
 806                 }
 807                 ASSERT(d_backing_inode(subdir));
 808
 809                 _debug("mkdir -> %p{%p{ino=%lu}}",
 810                        subdir,
 811                        d_backing_inode(subdir),
 812                        d_backing_inode(subdir)->i_ino);
 813         }
 814
 815         inode_unlock(d_inode(dir));
 816
 817         /* we need to make sure the subdir is a directory */
 818         ASSERT(d_backing_inode(subdir));
 819
 820         if (!d_can_lookup(subdir)) {
 821                 pr_err("%s is not a directory\n", dirname);
 822                 ret = -EIO;
 823                 goto check_error;
 824         }
 825
 826         ret = -EPERM;
 827         if (!(d_backing_inode(subdir)->i_opflags & IOP_XATTR) ||
 828             !d_backing_inode(subdir)->i_op->lookup ||
 829             !d_backing_inode(subdir)->i_op->mkdir ||
 830             !d_backing_inode(subdir)->i_op->create ||
 831             !d_backing_inode(subdir)->i_op->rename ||
 832             !d_backing_inode(subdir)->i_op->rmdir ||
 833             !d_backing_inode(subdir)->i_op->unlink)
 834                 goto check_error;
 835
 836         _leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
 837         return subdir;
 838
 839 check_error:
 840         dput(subdir);
 841         _leave(" = %d [check]", ret);
 842         return ERR_PTR(ret);
 843
 844 mkdir_error:
 845         inode_unlock(d_inode(dir));
 846         dput(subdir);
 847         pr_err("mkdir %s failed with error %d\n", dirname, ret);
 848         return ERR_PTR(ret);
 849
 850 lookup_error:
 851         inode_unlock(d_inode(dir));
 852         ret = PTR_ERR(subdir);
 853         pr_err("Lookup %s failed with error %d\n", dirname, ret);
 854         return ERR_PTR(ret);
 855
 856 nomem_d_alloc:
 857         inode_unlock(d_inode(dir));
 858         _leave(" = -ENOMEM");
 859         return ERR_PTR(-ENOMEM);
 860 }
 861
 862 /*
 863  * find out if an object is in use or not
 864  * - if finds object and it's not in use:
 865  *   - returns a pointer to the object and a reference on it
 866  *   - returns with the directory locked
 867  */
 868 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
 869                                               struct dentry *dir,
 870                                               char *filename)
 871 {
 872         struct cachefiles_object *object;
 873         struct rb_node *_n;
 874         struct dentry *victim;
 875         unsigned long start;
 876         int ret;
 877
 878         //_enter(",%pd/,%s",
 879         //       dir, filename);
 880
 881         /* look up the victim */
 882         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
 883
 884         start = jiffies;
 885         victim = lookup_one_len(filename, dir, strlen(filename));
 886         cachefiles_hist(cachefiles_lookup_histogram, start);
 887         if (IS_ERR(victim))
 888                 goto lookup_error;
 889
 890         //_debug("victim -> %p %s",
 891         //       victim, d_backing_inode(victim) ? "positive" : "negative");
 892
 893         /* if the object is no longer there then we probably retired the object
 894          * at the netfs's request whilst the cull was in progress
 895          */
 896         if (d_is_negative(victim)) {
 897                 inode_unlock(d_inode(dir));
 898                 dput(victim);
 899                 _leave(" = -ENOENT [absent]");
 900                 return ERR_PTR(-ENOENT);
 901         }
 902
 903         /* check to see if we're using this object */
 904         read_lock(&cache->active_lock);
 905
 906         _n = cache->active_nodes.rb_node;
 907
 908         while (_n) {
 909                 object = rb_entry(_n, struct cachefiles_object, active_node);
 910
 911                 if (object->dentry > victim)
 912                         _n = _n->rb_left;
 913                 else if (object->dentry < victim)
 914                         _n = _n->rb_right;
 915                 else
 916                         goto object_in_use;
 917         }
 918
 919         read_unlock(&cache->active_lock);
 920
 921         //_leave(" = %p", victim);
 922         return victim;
 923
 924 object_in_use:
 925         read_unlock(&cache->active_lock);
 926         inode_unlock(d_inode(dir));
 927         dput(victim);
 928         //_leave(" = -EBUSY [in use]");
 929         return ERR_PTR(-EBUSY);
 930
 931 lookup_error:
 932         inode_unlock(d_inode(dir));
 933         ret = PTR_ERR(victim);
 934         if (ret == -ENOENT) {
 935                 /* file or dir now absent - probably retired by netfs */
 936                 _leave(" = -ESTALE [absent]");
 937                 return ERR_PTR(-ESTALE);
 938         }
 939
 940         if (ret == -EIO) {
 941                 cachefiles_io_error(cache, "Lookup failed");
 942         } else if (ret != -ENOMEM) {
 943                 pr_err("Internal error: %d\n", ret);
 944                 ret = -EIO;
 945         }
 946
 947         _leave(" = %d", ret);
 948         return ERR_PTR(ret);
 949 }
 950
 951 /*
 952  * cull an object if it's not in use
 953  * - called only by cache manager daemon
 954  */
 955 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
 956                     char *filename)
 957 {
 958         struct dentry *victim;
 959         int ret;
 960
 961         _enter(",%pd/,%s", dir, filename);
 962
 963         victim = cachefiles_check_active(cache, dir, filename);
 964         if (IS_ERR(victim))
 965                 return PTR_ERR(victim);
 966
 967         _debug("victim -> %p %s",
 968                victim, d_backing_inode(victim) ? "positive" : "negative");
 969
 970         /* okay... the victim is not being used so we can cull it
 971          * - start by marking it as stale
 972          */
 973         _debug("victim is cullable");
 974
 975         ret = cachefiles_remove_object_xattr(cache, victim);
 976         if (ret < 0)
 977                 goto error_unlock;
 978
 979         /*  actually remove the victim (drops the dir mutex) */
 980         _debug("bury");
 981
 982         ret = cachefiles_bury_object(cache, NULL, dir, victim, false,
 983                                      FSCACHE_OBJECT_WAS_CULLED);
 984         if (ret < 0)
 985                 goto error;
 986
 987         dput(victim);
 988         _leave(" = 0");
 989         return 0;
 990
 991 error_unlock:
 992         inode_unlock(d_inode(dir));
 993 error:
 994         dput(victim);
 995         if (ret == -ENOENT) {
 996                 /* file or dir now absent - probably retired by netfs */
 997                 _leave(" = -ESTALE [absent]");
 998                 return -ESTALE;
 999         }
1000
1001         if (ret != -ENOMEM) {
1002                 pr_err("Internal error: %d\n", ret);
1003                 ret = -EIO;
1004         }
1005
1006         _leave(" = %d", ret);
1007         return ret;
1008 }
1009
1010 /*
1011  * find out if an object is in use or not
1012  * - called only by cache manager daemon
1013  * - returns -EBUSY or 0 to indicate whether an object is in use or not
1014  */
1015 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
1016                             char *filename)
1017 {
1018         struct dentry *victim;
1019
1020         //_enter(",%pd/,%s",
1021         //       dir, filename);
1022
1023         victim = cachefiles_check_active(cache, dir, filename);
1024         if (IS_ERR(victim))
1025                 return PTR_ERR(victim);
1026
1027         inode_unlock(d_inode(dir));
1028         dput(victim);
1029         //_leave(" = 0");
1030         return 0;
1031 }