root/fs/cachefiles/namei.c

DEFINITIONS

1. __cachefiles_printk_object
2. cachefiles_printk_object
3. cachefiles_mark_object_buried
4. cachefiles_mark_object_active
5. cachefiles_mark_object_inactive
6. cachefiles_bury_object
7. cachefiles_delete_object
8. cachefiles_walk_to_object
9. cachefiles_get_directory
10. cachefiles_check_active
11. cachefiles_cull
12. cachefiles_check_in_use

   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 (dhowells@redhat.com)
   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=%p\n",
  43                prefix, object->fscache.parent);
  44 
  45         spin_lock(&object->fscache.lock);
  46         cookie = object->fscache.cookie;
  47         if (cookie) {
  48                 pr_err("%scookie=%p [pr=%p nd=%p fl=%lx]\n",
  49                        prefix,
  50                        object->fscache.cookie,
  51                        object->fscache.cookie->parent,
  52                        object->fscache.cookie->netfs_data,
  53                        object->fscache.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] %p",
 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(",%p", object);
 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         _debug("remove %p from %p", rep, dir);
 302 
 303         /* non-directories can just be unlinked */
 304         if (!d_is_dir(rep)) {
 305                 _debug("unlink stale object");
 306 
 307                 path.mnt = cache->mnt;
 308                 path.dentry = dir;
 309                 ret = security_path_unlink(&path, rep);
 310                 if (ret < 0) {
 311                         cachefiles_io_error(cache, "Unlink security error");
 312                 } else {
 313                         trace_cachefiles_unlink(object, rep, why);
 314                         ret = vfs_unlink(d_inode(dir), rep, NULL);
 315 
 316                         if (preemptive)
 317                                 cachefiles_mark_object_buried(cache, rep, why);
 318                 }
 319 
 320                 inode_unlock(d_inode(dir));
 321 
 322                 if (ret == -EIO)
 323                         cachefiles_io_error(cache, "Unlink failed");
 324 
 325                 _leave(" = %d", ret);
 326                 return ret;
 327         }
 328 
 329         /* directories have to be moved to the graveyard */
 330         _debug("move stale object to graveyard");
 331         inode_unlock(d_inode(dir));
 332 
 333 try_again:
 334         /* first step is to make up a grave dentry in the graveyard */
 335         sprintf(nbuffer, "%08x%08x",
 336                 (uint32_t) ktime_get_real_seconds(),
 337                 (uint32_t) atomic_inc_return(&cache->gravecounter));
 338 
 339         /* do the multiway lock magic */
 340         trap = lock_rename(cache->graveyard, dir);
 341 
 342         /* do some checks before getting the grave dentry */
 343         if (rep->d_parent != dir || IS_DEADDIR(d_inode(rep))) {
 344                 /* the entry was probably culled when we dropped the parent dir
 345                  * lock */
 346                 unlock_rename(cache->graveyard, dir);
 347                 _leave(" = 0 [culled?]");
 348                 return 0;
 349         }
 350 
 351         if (!d_can_lookup(cache->graveyard)) {
 352                 unlock_rename(cache->graveyard, dir);
 353                 cachefiles_io_error(cache, "Graveyard no longer a directory");
 354                 return -EIO;
 355         }
 356 
 357         if (trap == rep) {
 358                 unlock_rename(cache->graveyard, dir);
 359                 cachefiles_io_error(cache, "May not make directory loop");
 360                 return -EIO;
 361         }
 362 
 363         if (d_mountpoint(rep)) {
 364                 unlock_rename(cache->graveyard, dir);
 365                 cachefiles_io_error(cache, "Mountpoint in cache");
 366                 return -EIO;
 367         }
 368 
 369         grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
 370         if (IS_ERR(grave)) {
 371                 unlock_rename(cache->graveyard, dir);
 372 
 373                 if (PTR_ERR(grave) == -ENOMEM) {
 374                         _leave(" = -ENOMEM");
 375                         return -ENOMEM;
 376                 }
 377 
 378                 cachefiles_io_error(cache, "Lookup error %ld",
 379                                     PTR_ERR(grave));
 380                 return -EIO;
 381         }
 382 
 383         if (d_is_positive(grave)) {
 384                 unlock_rename(cache->graveyard, dir);
 385                 dput(grave);
 386                 grave = NULL;
 387                 cond_resched();
 388                 goto try_again;
 389         }
 390 
 391         if (d_mountpoint(grave)) {
 392                 unlock_rename(cache->graveyard, dir);
 393                 dput(grave);
 394                 cachefiles_io_error(cache, "Mountpoint in graveyard");
 395                 return -EIO;
 396         }
 397 
 398         /* target should not be an ancestor of source */
 399         if (trap == grave) {
 400                 unlock_rename(cache->graveyard, dir);
 401                 dput(grave);
 402                 cachefiles_io_error(cache, "May not make directory loop");
 403                 return -EIO;
 404         }
 405 
 406         /* attempt the rename */
 407         path.mnt = cache->mnt;
 408         path.dentry = dir;
 409         path_to_graveyard.mnt = cache->mnt;
 410         path_to_graveyard.dentry = cache->graveyard;
 411         ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0);
 412         if (ret < 0) {
 413                 cachefiles_io_error(cache, "Rename security error %d", ret);
 414         } else {
 415                 trace_cachefiles_rename(object, rep, grave, why);
 416                 ret = vfs_rename(d_inode(dir), rep,
 417                                  d_inode(cache->graveyard), grave, NULL, 0);
 418                 if (ret != 0 && ret != -ENOMEM)
 419                         cachefiles_io_error(cache,
 420                                             "Rename failed with error %d", ret);
 421 
 422                 if (preemptive)
 423                         cachefiles_mark_object_buried(cache, rep, why);
 424         }
 425 
 426         unlock_rename(cache->graveyard, dir);
 427         dput(grave);
 428         _leave(" = 0");
 429         return 0;
 430 }
 431 
 432 /*
 433  * delete an object representation from the cache
 434  */
 435 int cachefiles_delete_object(struct cachefiles_cache *cache,
 436                              struct cachefiles_object *object)
 437 {
 438         struct dentry *dir;
 439         int ret;
 440 
 441         _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
 442 
 443         ASSERT(object->dentry);
 444         ASSERT(d_backing_inode(object->dentry));
 445         ASSERT(object->dentry->d_parent);
 446 
 447         dir = dget_parent(object->dentry);
 448 
 449         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
 450 
 451         if (test_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->fscache.flags)) {
 452                 /* object allocation for the same key preemptively deleted this
 453                  * object's file so that it could create its own file */
 454                 _debug("object preemptively buried");
 455                 inode_unlock(d_inode(dir));
 456                 ret = 0;
 457         } else {
 458                 /* we need to check that our parent is _still_ our parent - it
 459                  * may have been renamed */
 460                 if (dir == object->dentry->d_parent) {
 461                         ret = cachefiles_bury_object(cache, object, dir,
 462                                                      object->dentry, false,
 463                                                      FSCACHE_OBJECT_WAS_RETIRED);
 464                 } else {
 465                         /* it got moved, presumably by cachefilesd culling it,
 466                          * so it's no longer in the key path and we can ignore
 467                          * it */
 468                         inode_unlock(d_inode(dir));
 469                         ret = 0;
 470                 }
 471         }
 472 
 473         dput(dir);
 474         _leave(" = %d", ret);
 475         return ret;
 476 }
 477 
 478 /*
 479  * walk from the parent object to the child object through the backing
 480  * filesystem, creating directories as we go
 481  */
 482 int cachefiles_walk_to_object(struct cachefiles_object *parent,
 483                               struct cachefiles_object *object,
 484                               const char *key,
 485                               struct cachefiles_xattr *auxdata)
 486 {
 487         struct cachefiles_cache *cache;
 488         struct dentry *dir, *next = NULL;
 489         struct inode *inode;
 490         struct path path;
 491         unsigned long start;
 492         const char *name;
 493         int ret, nlen;
 494 
 495         _enter("OBJ%x{%p},OBJ%x,%s,",
 496                parent->fscache.debug_id, parent->dentry,
 497                object->fscache.debug_id, key);
 498 
 499         cache = container_of(parent->fscache.cache,
 500                              struct cachefiles_cache, cache);
 501         path.mnt = cache->mnt;
 502 
 503         ASSERT(parent->dentry);
 504         ASSERT(d_backing_inode(parent->dentry));
 505 
 506         if (!(d_is_dir(parent->dentry))) {
 507                 // TODO: convert file to dir
 508                 _leave("looking up in none directory");
 509                 return -ENOBUFS;
 510         }
 511 
 512         dir = dget(parent->dentry);
 513 
 514 advance:
 515         /* attempt to transit the first directory component */
 516         name = key;
 517         nlen = strlen(key);
 518 
 519         /* key ends in a double NUL */
 520         key = key + nlen + 1;
 521         if (!*key)
 522                 key = NULL;
 523 
 524 lookup_again:
 525         /* search the current directory for the element name */
 526         _debug("lookup '%s'", name);
 527 
 528         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
 529 
 530         start = jiffies;
 531         next = lookup_one_len(name, dir, nlen);
 532         cachefiles_hist(cachefiles_lookup_histogram, start);
 533         if (IS_ERR(next)) {
 534                 trace_cachefiles_lookup(object, next, NULL);
 535                 goto lookup_error;
 536         }
 537 
 538         inode = d_backing_inode(next);
 539         trace_cachefiles_lookup(object, next, inode);
 540         _debug("next -> %p %s", next, inode ? "positive" : "negative");
 541 
 542         if (!key)
 543                 object->new = !inode;
 544 
 545         /* if this element of the path doesn't exist, then the lookup phase
 546          * failed, and we can release any readers in the certain knowledge that
 547          * there's nothing for them to actually read */
 548         if (d_is_negative(next))
 549                 fscache_object_lookup_negative(&object->fscache);
 550 
 551         /* we need to create the object if it's negative */
 552         if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
 553                 /* index objects and intervening tree levels must be subdirs */
 554                 if (d_is_negative(next)) {
 555                         ret = cachefiles_has_space(cache, 1, 0);
 556                         if (ret < 0)
 557                                 goto no_space_error;
 558 
 559                         path.dentry = dir;
 560                         ret = security_path_mkdir(&path, next, 0);
 561                         if (ret < 0)
 562                                 goto create_error;
 563                         start = jiffies;
 564                         ret = vfs_mkdir(d_inode(dir), next, 0);
 565                         cachefiles_hist(cachefiles_mkdir_histogram, start);
 566                         if (!key)
 567                                 trace_cachefiles_mkdir(object, next, ret);
 568                         if (ret < 0)
 569                                 goto create_error;
 570 
 571                         if (unlikely(d_unhashed(next))) {
 572                                 dput(next);
 573                                 inode_unlock(d_inode(dir));
 574                                 goto lookup_again;
 575                         }
 576                         ASSERT(d_backing_inode(next));
 577 
 578                         _debug("mkdir -> %p{%p{ino=%lu}}",
 579                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
 580 
 581                 } else if (!d_can_lookup(next)) {
 582                         pr_err("inode %lu is not a directory\n",
 583                                d_backing_inode(next)->i_ino);
 584                         ret = -ENOBUFS;
 585                         goto error;
 586                 }
 587 
 588         } else {
 589                 /* non-index objects start out life as files */
 590                 if (d_is_negative(next)) {
 591                         ret = cachefiles_has_space(cache, 1, 0);
 592                         if (ret < 0)
 593                                 goto no_space_error;
 594 
 595                         path.dentry = dir;
 596                         ret = security_path_mknod(&path, next, S_IFREG, 0);
 597                         if (ret < 0)
 598                                 goto create_error;
 599                         start = jiffies;
 600                         ret = vfs_create(d_inode(dir), next, S_IFREG, true);
 601                         cachefiles_hist(cachefiles_create_histogram, start);
 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 -> %p{%p{ino=%lu}}",
 609                                next, d_backing_inode(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         unsigned long start;
 760         struct path path;
 761         int ret;
 762 
 763         _enter(",,%s", dirname);
 764 
 765         /* search the current directory for the element name */
 766         inode_lock(d_inode(dir));
 767 
 768 retry:
 769         start = jiffies;
 770         subdir = lookup_one_len(dirname, dir, strlen(dirname));
 771         cachefiles_hist(cachefiles_lookup_histogram, start);
 772         if (IS_ERR(subdir)) {
 773                 if (PTR_ERR(subdir) == -ENOMEM)
 774                         goto nomem_d_alloc;
 775                 goto lookup_error;
 776         }
 777 
 778         _debug("subdir -> %p %s",
 779                subdir, d_backing_inode(subdir) ? "positive" : "negative");
 780 
 781         /* we need to create the subdir if it doesn't exist yet */
 782         if (d_is_negative(subdir)) {
 783                 ret = cachefiles_has_space(cache, 1, 0);
 784                 if (ret < 0)
 785                         goto mkdir_error;
 786 
 787                 _debug("attempt mkdir");
 788 
 789                 path.mnt = cache->mnt;
 790                 path.dentry = dir;
 791                 ret = security_path_mkdir(&path, subdir, 0700);
 792                 if (ret < 0)
 793                         goto mkdir_error;
 794                 ret = vfs_mkdir(d_inode(dir), subdir, 0700);
 795                 if (ret < 0)
 796                         goto mkdir_error;
 797 
 798                 if (unlikely(d_unhashed(subdir))) {
 799                         dput(subdir);
 800                         goto retry;
 801                 }
 802                 ASSERT(d_backing_inode(subdir));
 803 
 804                 _debug("mkdir -> %p{%p{ino=%lu}}",
 805                        subdir,
 806                        d_backing_inode(subdir),
 807                        d_backing_inode(subdir)->i_ino);
 808         }
 809 
 810         inode_unlock(d_inode(dir));
 811 
 812         /* we need to make sure the subdir is a directory */
 813         ASSERT(d_backing_inode(subdir));
 814 
 815         if (!d_can_lookup(subdir)) {
 816                 pr_err("%s is not a directory\n", dirname);
 817                 ret = -EIO;
 818                 goto check_error;
 819         }
 820 
 821         ret = -EPERM;
 822         if (!(d_backing_inode(subdir)->i_opflags & IOP_XATTR) ||
 823             !d_backing_inode(subdir)->i_op->lookup ||
 824             !d_backing_inode(subdir)->i_op->mkdir ||
 825             !d_backing_inode(subdir)->i_op->create ||
 826             !d_backing_inode(subdir)->i_op->rename ||
 827             !d_backing_inode(subdir)->i_op->rmdir ||
 828             !d_backing_inode(subdir)->i_op->unlink)
 829                 goto check_error;
 830 
 831         _leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
 832         return subdir;
 833 
 834 check_error:
 835         dput(subdir);
 836         _leave(" = %d [check]", ret);
 837         return ERR_PTR(ret);
 838 
 839 mkdir_error:
 840         inode_unlock(d_inode(dir));
 841         dput(subdir);
 842         pr_err("mkdir %s failed with error %d\n", dirname, ret);
 843         return ERR_PTR(ret);
 844 
 845 lookup_error:
 846         inode_unlock(d_inode(dir));
 847         ret = PTR_ERR(subdir);
 848         pr_err("Lookup %s failed with error %d\n", dirname, ret);
 849         return ERR_PTR(ret);
 850 
 851 nomem_d_alloc:
 852         inode_unlock(d_inode(dir));
 853         _leave(" = -ENOMEM");
 854         return ERR_PTR(-ENOMEM);
 855 }
 856 
 857 /*
 858  * find out if an object is in use or not
 859  * - if finds object and it's not in use:
 860  *   - returns a pointer to the object and a reference on it
 861  *   - returns with the directory locked
 862  */
 863 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
 864                                               struct dentry *dir,
 865                                               char *filename)
 866 {
 867         struct cachefiles_object *object;
 868         struct rb_node *_n;
 869         struct dentry *victim;
 870         unsigned long start;
 871         int ret;
 872 
 873         //_enter(",%pd/,%s",
 874         //       dir, filename);
 875 
 876         /* look up the victim */
 877         inode_lock_nested(d_inode(dir), I_MUTEX_PARENT);
 878 
 879         start = jiffies;
 880         victim = lookup_one_len(filename, dir, strlen(filename));
 881         cachefiles_hist(cachefiles_lookup_histogram, start);
 882         if (IS_ERR(victim))
 883                 goto lookup_error;
 884 
 885         //_debug("victim -> %p %s",
 886         //       victim, d_backing_inode(victim) ? "positive" : "negative");
 887 
 888         /* if the object is no longer there then we probably retired the object
 889          * at the netfs's request whilst the cull was in progress
 890          */
 891         if (d_is_negative(victim)) {
 892                 inode_unlock(d_inode(dir));
 893                 dput(victim);
 894                 _leave(" = -ENOENT [absent]");
 895                 return ERR_PTR(-ENOENT);
 896         }
 897 
 898         /* check to see if we're using this object */
 899         read_lock(&cache->active_lock);
 900 
 901         _n = cache->active_nodes.rb_node;
 902 
 903         while (_n) {
 904                 object = rb_entry(_n, struct cachefiles_object, active_node);
 905 
 906                 if (object->dentry > victim)
 907                         _n = _n->rb_left;
 908                 else if (object->dentry < victim)
 909                         _n = _n->rb_right;
 910                 else
 911                         goto object_in_use;
 912         }
 913 
 914         read_unlock(&cache->active_lock);
 915 
 916         //_leave(" = %p", victim);
 917         return victim;
 918 
 919 object_in_use:
 920         read_unlock(&cache->active_lock);
 921         inode_unlock(d_inode(dir));
 922         dput(victim);
 923         //_leave(" = -EBUSY [in use]");
 924         return ERR_PTR(-EBUSY);
 925 
 926 lookup_error:
 927         inode_unlock(d_inode(dir));
 928         ret = PTR_ERR(victim);
 929         if (ret == -ENOENT) {
 930                 /* file or dir now absent - probably retired by netfs */
 931                 _leave(" = -ESTALE [absent]");
 932                 return ERR_PTR(-ESTALE);
 933         }
 934 
 935         if (ret == -EIO) {
 936                 cachefiles_io_error(cache, "Lookup failed");
 937         } else if (ret != -ENOMEM) {
 938                 pr_err("Internal error: %d\n", ret);
 939                 ret = -EIO;
 940         }
 941 
 942         _leave(" = %d", ret);
 943         return ERR_PTR(ret);
 944 }
 945 
 946 /*
 947  * cull an object if it's not in use
 948  * - called only by cache manager daemon
 949  */
 950 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
 951                     char *filename)
 952 {
 953         struct dentry *victim;
 954         int ret;
 955 
 956         _enter(",%pd/,%s", dir, filename);
 957 
 958         victim = cachefiles_check_active(cache, dir, filename);
 959         if (IS_ERR(victim))
 960                 return PTR_ERR(victim);
 961 
 962         _debug("victim -> %p %s",
 963                victim, d_backing_inode(victim) ? "positive" : "negative");
 964 
 965         /* okay... the victim is not being used so we can cull it
 966          * - start by marking it as stale
 967          */
 968         _debug("victim is cullable");
 969 
 970         ret = cachefiles_remove_object_xattr(cache, victim);
 971         if (ret < 0)
 972                 goto error_unlock;
 973 
 974         /*  actually remove the victim (drops the dir mutex) */
 975         _debug("bury");
 976 
 977         ret = cachefiles_bury_object(cache, NULL, dir, victim, false,
 978                                      FSCACHE_OBJECT_WAS_CULLED);
 979         if (ret < 0)
 980                 goto error;
 981 
 982         dput(victim);
 983         _leave(" = 0");
 984         return 0;
 985 
 986 error_unlock:
 987         inode_unlock(d_inode(dir));
 988 error:
 989         dput(victim);
 990         if (ret == -ENOENT) {
 991                 /* file or dir now absent - probably retired by netfs */
 992                 _leave(" = -ESTALE [absent]");
 993                 return -ESTALE;
 994         }
 995 
 996         if (ret != -ENOMEM) {
 997                 pr_err("Internal error: %d\n", ret);
 998                 ret = -EIO;
 999         }
1000 
1001         _leave(" = %d", ret);
1002         return ret;
1003 }
1004 
1005 /*
1006  * find out if an object is in use or not
1007  * - called only by cache manager daemon
1008  * - returns -EBUSY or 0 to indicate whether an object is in use or not
1009  */
1010 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
1011                             char *filename)
1012 {
1013         struct dentry *victim;
1014 
1015         //_enter(",%pd/,%s",
1016         //       dir, filename);
1017 
1018         victim = cachefiles_check_active(cache, dir, filename);
1019         if (IS_ERR(victim))
1020                 return PTR_ERR(victim);
1021 
1022         inode_unlock(d_inode(dir));
1023         dput(victim);
1024         //_leave(" = 0");
1025         return 0;
1026 }