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                                 u8 *keybuf)
  34 {
  35         struct fscache_cookie *cookie;
  36         unsigned keylen, 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                 if (keybuf && cookie->def)
  59                         keylen = cookie->def->get_key(cookie->netfs_data, keybuf,
  60                                                       CACHEFILES_KEYBUF_SIZE);
  61                 else
  62                         keylen = 0;
  63         } else {
  64                 pr_err("%scookie=NULL\n", prefix);
  65                 keylen = 0;
  66         }
  67         spin_unlock(&object->fscache.lock);
  68
  69         if (keylen) {
  70                 pr_err("%skey=[%u] '", prefix, keylen);
  71                 for (loop = 0; loop < keylen; loop++)
  72                         pr_cont("%02x", keybuf[loop]);
  73                 pr_cont("'\n");
  74         }
  75 }
  76
  77 /*
  78  * dump debugging info about a pair of objects
  79  */
  80 static noinline void cachefiles_printk_object(struct cachefiles_object *object,
  81                                               struct cachefiles_object *xobject)
  82 {
  83         u8 *keybuf;
  84
  85         keybuf = kmalloc(CACHEFILES_KEYBUF_SIZE, GFP_NOIO);
  86         if (object)
  87                 __cachefiles_printk_object(object, "", keybuf);
  88         if (xobject)
  89                 __cachefiles_printk_object(xobject, "x", keybuf);
  90         kfree(keybuf);
  91 }
  92
  93 /*
  94  * mark the owner of a dentry, if there is one, to indicate that that dentry
  95  * has been preemptively deleted
  96  * - the caller must hold the i_mutex on the dentry's parent as required to
  97  *   call vfs_unlink(), vfs_rmdir() or vfs_rename()
  98  */
  99 static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
 100                                           struct dentry *dentry,
 101                                           enum fscache_why_object_killed why)
 102 {
 103         struct cachefiles_object *object;
 104         struct rb_node *p;
 105
 106         _enter(",'%pd'", dentry);
 107
 108         write_lock(&cache->active_lock);
 109
 110         p = cache->active_nodes.rb_node;
 111         while (p) {
 112                 object = rb_entry(p, struct cachefiles_object, active_node);
 113                 if (object->dentry > dentry)
 114                         p = p->rb_left;
 115                 else if (object->dentry < dentry)
 116                         p = p->rb_right;
 117                 else
 118                         goto found_dentry;
 119         }
 120
 121         write_unlock(&cache->active_lock);
 122         _leave(" [no owner]");
 123         return;
 124
 125         /* found the dentry for  */
 126 found_dentry:
 127         kdebug("preemptive burial: OBJ%x [%s] %p",
 128                object->fscache.debug_id,
 129                object->fscache.state->name,
 130                dentry);
 131
 132         if (fscache_object_is_live(&object->fscache)) {
 133                 pr_err("\n");
 134                 pr_err("Error: Can't preemptively bury live object\n");
 135                 cachefiles_printk_object(object, NULL);
 136         } else {
 137                 if (why != FSCACHE_OBJECT_IS_STALE)
 138                         fscache_object_mark_killed(&object->fscache, why);
 139         }
 140
 141         write_unlock(&cache->active_lock);
 142         _leave(" [owner marked]");
 143 }
 144
 145 /*
 146  * record the fact that an object is now active
 147  */
 148 static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
 149                                          struct cachefiles_object *object)
 150 {
 151         struct cachefiles_object *xobject;
 152         struct rb_node **_p, *_parent = NULL;
 153         struct dentry *dentry;
 154
 155         _enter(",%p", object);
 156
 157 try_again:
 158         write_lock(&cache->active_lock);
 159
 160         if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
 161                 pr_err("Error: Object already active\n");
 162                 cachefiles_printk_object(object, NULL);
 163                 BUG();
 164         }
 165
 166         dentry = object->dentry;
 167         _p = &cache->active_nodes.rb_node;
 168         while (*_p) {
 169                 _parent = *_p;
 170                 xobject = rb_entry(_parent,
 171                                    struct cachefiles_object, active_node);
 172
 173                 ASSERT(xobject != object);
 174
 175                 if (xobject->dentry > dentry)
 176                         _p = &(*_p)->rb_left;
 177                 else if (xobject->dentry < dentry)
 178                         _p = &(*_p)->rb_right;
 179                 else
 180                         goto wait_for_old_object;
 181         }
 182
 183         rb_link_node(&object->active_node, _parent, _p);
 184         rb_insert_color(&object->active_node, &cache->active_nodes);
 185
 186         write_unlock(&cache->active_lock);
 187         _leave(" = 0");
 188         return 0;
 189
 190         /* an old object from a previous incarnation is hogging the slot - we
 191          * need to wait for it to be destroyed */
 192 wait_for_old_object:
 193         if (fscache_object_is_live(&xobject->fscache)) {
 194                 pr_err("\n");
 195                 pr_err("Error: Unexpected object collision\n");
 196                 cachefiles_printk_object(object, xobject);
 197                 BUG();
 198         }
 199         atomic_inc(&xobject->usage);
 200         write_unlock(&cache->active_lock);
 201
 202         if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 203                 wait_queue_head_t *wq;
 204
 205                 signed long timeout = 60 * HZ;
 206                 wait_queue_t wait;
 207                 bool requeue;
 208
 209                 /* if the object we're waiting for is queued for processing,
 210                  * then just put ourselves on the queue behind it */
 211                 if (work_pending(&xobject->fscache.work)) {
 212                         _debug("queue OBJ%x behind OBJ%x immediately",
 213                                object->fscache.debug_id,
 214                                xobject->fscache.debug_id);
 215                         goto requeue;
 216                 }
 217
 218                 /* otherwise we sleep until either the object we're waiting for
 219                  * is done, or the fscache_object is congested */
 220                 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
 221                 init_wait(&wait);
 222                 requeue = false;
 223                 do {
 224                         prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
 225                         if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
 226                                 break;
 227
 228                         requeue = fscache_object_sleep_till_congested(&timeout);
 229                 } while (timeout > 0 && !requeue);
 230                 finish_wait(wq, &wait);
 231
 232                 if (requeue &&
 233                     test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 234                         _debug("queue OBJ%x behind OBJ%x after wait",
 235                                object->fscache.debug_id,
 236                                xobject->fscache.debug_id);
 237                         goto requeue;
 238                 }
 239
 240                 if (timeout <= 0) {
 241                         pr_err("\n");
 242                         pr_err("Error: Overlong wait for old active object to go away\n");
 243                         cachefiles_printk_object(object, xobject);
 244                         goto requeue;
 245                 }
 246         }
 247
 248         ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
 249
 250         cache->cache.ops->put_object(&xobject->fscache);
 251         goto try_again;
 252
 253 requeue:
 254         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 255         cache->cache.ops->put_object(&xobject->fscache);
 256         _leave(" = -ETIMEDOUT");
 257         return -ETIMEDOUT;
 258 }
 259
 260 /*
 261  * delete an object representation from the cache
 262  * - file backed objects are unlinked
 263  * - directory backed objects are stuffed into the graveyard for userspace to
 264  *   delete
 265  * - unlocks the directory mutex
 266  */
 267 static int cachefiles_bury_object(struct cachefiles_cache *cache,
 268                                   struct dentry *dir,
 269                                   struct dentry *rep,
 270                                   bool preemptive,
 271                                   enum fscache_why_object_killed why)
 272 {
 273         struct dentry *grave, *trap;
 274         struct path path, path_to_graveyard;
 275         char nbuffer[8 + 8 + 1];
 276         int ret;
 277
 278         _enter(",'%pd','%pd'", dir, rep);
 279
 280         _debug("remove %p from %p", rep, dir);
 281
 282         /* non-directories can just be unlinked */
 283         if (!d_is_dir(rep)) {
 284                 _debug("unlink stale object");
 285
 286                 path.mnt = cache->mnt;
 287                 path.dentry = dir;
 288                 ret = security_path_unlink(&path, rep);
 289                 if (ret < 0) {
 290                         cachefiles_io_error(cache, "Unlink security error");
 291                 } else {
 292                         ret = vfs_unlink(d_inode(dir), rep, NULL);
 293
 294                         if (preemptive)
 295                                 cachefiles_mark_object_buried(cache, rep, why);
 296                 }
 297
 298                 mutex_unlock(&d_inode(dir)->i_mutex);
 299
 300                 if (ret == -EIO)
 301                         cachefiles_io_error(cache, "Unlink failed");
 302
 303                 _leave(" = %d", ret);
 304                 return ret;
 305         }
 306
 307         /* directories have to be moved to the graveyard */
 308         _debug("move stale object to graveyard");
 309         mutex_unlock(&d_inode(dir)->i_mutex);
 310
 311 try_again:
 312         /* first step is to make up a grave dentry in the graveyard */
 313         sprintf(nbuffer, "%08x%08x",
 314                 (uint32_t) get_seconds(),
 315                 (uint32_t) atomic_inc_return(&cache->gravecounter));
 316
 317         /* do the multiway lock magic */
 318         trap = lock_rename(cache->graveyard, dir);
 319
 320         /* do some checks before getting the grave dentry */
 321         if (rep->d_parent != dir) {
 322                 /* the entry was probably culled when we dropped the parent dir
 323                  * lock */
 324                 unlock_rename(cache->graveyard, dir);
 325                 _leave(" = 0 [culled?]");
 326                 return 0;
 327         }
 328
 329         if (!d_can_lookup(cache->graveyard)) {
 330                 unlock_rename(cache->graveyard, dir);
 331                 cachefiles_io_error(cache, "Graveyard no longer a directory");
 332                 return -EIO;
 333         }
 334
 335         if (trap == rep) {
 336                 unlock_rename(cache->graveyard, dir);
 337                 cachefiles_io_error(cache, "May not make directory loop");
 338                 return -EIO;
 339         }
 340
 341         if (d_mountpoint(rep)) {
 342                 unlock_rename(cache->graveyard, dir);
 343                 cachefiles_io_error(cache, "Mountpoint in cache");
 344                 return -EIO;
 345         }
 346
 347         grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
 348         if (IS_ERR(grave)) {
 349                 unlock_rename(cache->graveyard, dir);
 350
 351                 if (PTR_ERR(grave) == -ENOMEM) {
 352                         _leave(" = -ENOMEM");
 353                         return -ENOMEM;
 354                 }
 355
 356                 cachefiles_io_error(cache, "Lookup error %ld",
 357                                     PTR_ERR(grave));
 358                 return -EIO;
 359         }
 360
 361         if (d_is_positive(grave)) {
 362                 unlock_rename(cache->graveyard, dir);
 363                 dput(grave);
 364                 grave = NULL;
 365                 cond_resched();
 366                 goto try_again;
 367         }
 368
 369         if (d_mountpoint(grave)) {
 370                 unlock_rename(cache->graveyard, dir);
 371                 dput(grave);
 372                 cachefiles_io_error(cache, "Mountpoint in graveyard");
 373                 return -EIO;
 374         }
 375
 376         /* target should not be an ancestor of source */
 377         if (trap == grave) {
 378                 unlock_rename(cache->graveyard, dir);
 379                 dput(grave);
 380                 cachefiles_io_error(cache, "May not make directory loop");
 381                 return -EIO;
 382         }
 383
 384         /* attempt the rename */
 385         path.mnt = cache->mnt;
 386         path.dentry = dir;
 387         path_to_graveyard.mnt = cache->mnt;
 388         path_to_graveyard.dentry = cache->graveyard;
 389         ret = security_path_rename(&path, rep, &path_to_graveyard, grave, 0);
 390         if (ret < 0) {
 391                 cachefiles_io_error(cache, "Rename security error %d", ret);
 392         } else {
 393                 ret = vfs_rename(d_inode(dir), rep,
 394                                  d_inode(cache->graveyard), grave, NULL, 0);
 395                 if (ret != 0 && ret != -ENOMEM)
 396                         cachefiles_io_error(cache,
 397                                             "Rename failed with error %d", ret);
 398
 399                 if (preemptive)
 400                         cachefiles_mark_object_buried(cache, rep, why);
 401         }
 402
 403         unlock_rename(cache->graveyard, dir);
 404         dput(grave);
 405         _leave(" = 0");
 406         return 0;
 407 }
 408
 409 /*
 410  * delete an object representation from the cache
 411  */
 412 int cachefiles_delete_object(struct cachefiles_cache *cache,
 413                              struct cachefiles_object *object)
 414 {
 415         struct dentry *dir;
 416         int ret;
 417
 418         _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
 419
 420         ASSERT(object->dentry);
 421         ASSERT(d_backing_inode(object->dentry));
 422         ASSERT(object->dentry->d_parent);
 423
 424         dir = dget_parent(object->dentry);
 425
 426         mutex_lock_nested(&d_inode(dir)->i_mutex, I_MUTEX_PARENT);
 427
 428         if (test_bit(FSCACHE_OBJECT_KILLED_BY_CACHE, &object->fscache.flags)) {
 429                 /* object allocation for the same key preemptively deleted this
 430                  * object's file so that it could create its own file */
 431                 _debug("object preemptively buried");
 432                 mutex_unlock(&d_inode(dir)->i_mutex);
 433                 ret = 0;
 434         } else {
 435                 /* we need to check that our parent is _still_ our parent - it
 436                  * may have been renamed */
 437                 if (dir == object->dentry->d_parent) {
 438                         ret = cachefiles_bury_object(cache, dir,
 439                                                      object->dentry, false,
 440                                                      FSCACHE_OBJECT_WAS_RETIRED);
 441                 } else {
 442                         /* it got moved, presumably by cachefilesd culling it,
 443                          * so it's no longer in the key path and we can ignore
 444                          * it */
 445                         mutex_unlock(&d_inode(dir)->i_mutex);
 446                         ret = 0;
 447                 }
 448         }
 449
 450         dput(dir);
 451         _leave(" = %d", ret);
 452         return ret;
 453 }
 454
 455 /*
 456  * walk from the parent object to the child object through the backing
 457  * filesystem, creating directories as we go
 458  */
 459 int cachefiles_walk_to_object(struct cachefiles_object *parent,
 460                               struct cachefiles_object *object,
 461                               const char *key,
 462                               struct cachefiles_xattr *auxdata)
 463 {
 464         struct cachefiles_cache *cache;
 465         struct dentry *dir, *next = NULL;
 466         struct path path;
 467         unsigned long start;
 468         const char *name;
 469         int ret, nlen;
 470
 471         _enter("OBJ%x{%p},OBJ%x,%s,",
 472                parent->fscache.debug_id, parent->dentry,
 473                object->fscache.debug_id, key);
 474
 475         cache = container_of(parent->fscache.cache,
 476                              struct cachefiles_cache, cache);
 477         path.mnt = cache->mnt;
 478
 479         ASSERT(parent->dentry);
 480         ASSERT(d_backing_inode(parent->dentry));
 481
 482         if (!(d_is_dir(parent->dentry))) {
 483                 // TODO: convert file to dir
 484                 _leave("looking up in none directory");
 485                 return -ENOBUFS;
 486         }
 487
 488         dir = dget(parent->dentry);
 489
 490 advance:
 491         /* attempt to transit the first directory component */
 492         name = key;
 493         nlen = strlen(key);
 494
 495         /* key ends in a double NUL */
 496         key = key + nlen + 1;
 497         if (!*key)
 498                 key = NULL;
 499
 500 lookup_again:
 501         /* search the current directory for the element name */
 502         _debug("lookup '%s'", name);
 503
 504         mutex_lock_nested(&d_inode(dir)->i_mutex, I_MUTEX_PARENT);
 505
 506         start = jiffies;
 507         next = lookup_one_len(name, dir, nlen);
 508         cachefiles_hist(cachefiles_lookup_histogram, start);
 509         if (IS_ERR(next))
 510                 goto lookup_error;
 511
 512         _debug("next -> %p %s", next, d_backing_inode(next) ? "positive" : "negative");
 513
 514         if (!key)
 515                 object->new = !d_backing_inode(next);
 516
 517         /* if this element of the path doesn't exist, then the lookup phase
 518          * failed, and we can release any readers in the certain knowledge that
 519          * there's nothing for them to actually read */
 520         if (d_is_negative(next))
 521                 fscache_object_lookup_negative(&object->fscache);
 522
 523         /* we need to create the object if it's negative */
 524         if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
 525                 /* index objects and intervening tree levels must be subdirs */
 526                 if (d_is_negative(next)) {
 527                         ret = cachefiles_has_space(cache, 1, 0);
 528                         if (ret < 0)
 529                                 goto no_space_error;
 530
 531                         path.dentry = dir;
 532                         ret = security_path_mkdir(&path, next, 0);
 533                         if (ret < 0)
 534                                 goto create_error;
 535                         start = jiffies;
 536                         ret = vfs_mkdir(d_inode(dir), next, 0);
 537                         cachefiles_hist(cachefiles_mkdir_histogram, start);
 538                         if (ret < 0)
 539                                 goto create_error;
 540
 541                         ASSERT(d_backing_inode(next));
 542
 543                         _debug("mkdir -> %p{%p{ino=%lu}}",
 544                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
 545
 546                 } else if (!d_can_lookup(next)) {
 547                         pr_err("inode %lu is not a directory\n",
 548                                d_backing_inode(next)->i_ino);
 549                         ret = -ENOBUFS;
 550                         goto error;
 551                 }
 552
 553         } else {
 554                 /* non-index objects start out life as files */
 555                 if (d_is_negative(next)) {
 556                         ret = cachefiles_has_space(cache, 1, 0);
 557                         if (ret < 0)
 558                                 goto no_space_error;
 559
 560                         path.dentry = dir;
 561                         ret = security_path_mknod(&path, next, S_IFREG, 0);
 562                         if (ret < 0)
 563                                 goto create_error;
 564                         start = jiffies;
 565                         ret = vfs_create(d_inode(dir), next, S_IFREG, true);
 566                         cachefiles_hist(cachefiles_create_histogram, start);
 567                         if (ret < 0)
 568                                 goto create_error;
 569
 570                         ASSERT(d_backing_inode(next));
 571
 572                         _debug("create -> %p{%p{ino=%lu}}",
 573                                next, d_backing_inode(next), d_backing_inode(next)->i_ino);
 574
 575                 } else if (!d_can_lookup(next) &&
 576                            !d_is_reg(next)
 577                            ) {
 578                         pr_err("inode %lu is not a file or directory\n",
 579                                d_backing_inode(next)->i_ino);
 580                         ret = -ENOBUFS;
 581                         goto error;
 582                 }
 583         }
 584
 585         /* process the next component */
 586         if (key) {
 587                 _debug("advance");
 588                 mutex_unlock(&d_inode(dir)->i_mutex);
 589                 dput(dir);
 590                 dir = next;
 591                 next = NULL;
 592                 goto advance;
 593         }
 594
 595         /* we've found the object we were looking for */
 596         object->dentry = next;
 597
 598         /* if we've found that the terminal object exists, then we need to
 599          * check its attributes and delete it if it's out of date */
 600         if (!object->new) {
 601                 _debug("validate '%pd'", next);
 602
 603                 ret = cachefiles_check_object_xattr(object, auxdata);
 604                 if (ret == -ESTALE) {
 605                         /* delete the object (the deleter drops the directory
 606                          * mutex) */
 607                         object->dentry = NULL;
 608
 609                         ret = cachefiles_bury_object(cache, dir, next, true,
 610                                                      FSCACHE_OBJECT_IS_STALE);
 611                         dput(next);
 612                         next = NULL;
 613
 614                         if (ret < 0)
 615                                 goto delete_error;
 616
 617                         _debug("redo lookup");
 618                         fscache_object_retrying_stale(&object->fscache);
 619                         goto lookup_again;
 620                 }
 621         }
 622
 623         /* note that we're now using this object */
 624         ret = cachefiles_mark_object_active(cache, object);
 625
 626         mutex_unlock(&d_inode(dir)->i_mutex);
 627         dput(dir);
 628         dir = NULL;
 629
 630         if (ret == -ETIMEDOUT)
 631                 goto mark_active_timed_out;
 632
 633         _debug("=== OBTAINED_OBJECT ===");
 634
 635         if (object->new) {
 636                 /* attach data to a newly constructed terminal object */
 637                 ret = cachefiles_set_object_xattr(object, auxdata);
 638                 if (ret < 0)
 639                         goto check_error;
 640         } else {
 641                 /* always update the atime on an object we've just looked up
 642                  * (this is used to keep track of culling, and atimes are only
 643                  * updated by read, write and readdir but not lookup or
 644                  * open) */
 645                 path.dentry = next;
 646                 touch_atime(&path);
 647         }
 648
 649         /* open a file interface onto a data file */
 650         if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
 651                 if (d_is_reg(object->dentry)) {
 652                         const struct address_space_operations *aops;
 653
 654                         ret = -EPERM;
 655                         aops = d_backing_inode(object->dentry)->i_mapping->a_ops;
 656                         if (!aops->bmap)
 657                                 goto check_error;
 658                         if (object->dentry->d_sb->s_blocksize > PAGE_SIZE)
 659                                 goto check_error;
 660
 661                         object->backer = object->dentry;
 662                 } else {
 663                         BUG(); // TODO: open file in data-class subdir
 664                 }
 665         }
 666
 667         object->new = 0;
 668         fscache_obtained_object(&object->fscache);
 669
 670         _leave(" = 0 [%lu]", d_backing_inode(object->dentry)->i_ino);
 671         return 0;
 672
 673 no_space_error:
 674         fscache_object_mark_killed(&object->fscache, FSCACHE_OBJECT_NO_SPACE);
 675 create_error:
 676         _debug("create error %d", ret);
 677         if (ret == -EIO)
 678                 cachefiles_io_error(cache, "Create/mkdir failed");
 679         goto error;
 680
 681 mark_active_timed_out:
 682         _debug("mark active timed out");
 683         goto release_dentry;
 684
 685 check_error:
 686         _debug("check error %d", ret);
 687         write_lock(&cache->active_lock);
 688         rb_erase(&object->active_node, &cache->active_nodes);
 689         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 690         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
 691         write_unlock(&cache->active_lock);
 692 release_dentry:
 693         dput(object->dentry);
 694         object->dentry = NULL;
 695         goto error_out;
 696
 697 delete_error:
 698         _debug("delete error %d", ret);
 699         goto error_out2;
 700
 701 lookup_error:
 702         _debug("lookup error %ld", PTR_ERR(next));
 703         ret = PTR_ERR(next);
 704         if (ret == -EIO)
 705                 cachefiles_io_error(cache, "Lookup failed");
 706         next = NULL;
 707 error:
 708         mutex_unlock(&d_inode(dir)->i_mutex);
 709         dput(next);
 710 error_out2:
 711         dput(dir);
 712 error_out:
 713         _leave(" = error %d", -ret);
 714         return ret;
 715 }
 716
 717 /*
 718  * get a subdirectory
 719  */
 720 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
 721                                         struct dentry *dir,
 722                                         const char *dirname)
 723 {
 724         struct dentry *subdir;
 725         unsigned long start;
 726         struct path path;
 727         int ret;
 728
 729         _enter(",,%s", dirname);
 730
 731         /* search the current directory for the element name */
 732         mutex_lock(&d_inode(dir)->i_mutex);
 733
 734         start = jiffies;
 735         subdir = lookup_one_len(dirname, dir, strlen(dirname));
 736         cachefiles_hist(cachefiles_lookup_histogram, start);
 737         if (IS_ERR(subdir)) {
 738                 if (PTR_ERR(subdir) == -ENOMEM)
 739                         goto nomem_d_alloc;
 740                 goto lookup_error;
 741         }
 742
 743         _debug("subdir -> %p %s",
 744                subdir, d_backing_inode(subdir) ? "positive" : "negative");
 745
 746         /* we need to create the subdir if it doesn't exist yet */
 747         if (d_is_negative(subdir)) {
 748                 ret = cachefiles_has_space(cache, 1, 0);
 749                 if (ret < 0)
 750                         goto mkdir_error;
 751
 752                 _debug("attempt mkdir");
 753
 754                 path.mnt = cache->mnt;
 755                 path.dentry = dir;
 756                 ret = security_path_mkdir(&path, subdir, 0700);
 757                 if (ret < 0)
 758                         goto mkdir_error;
 759                 ret = vfs_mkdir(d_inode(dir), subdir, 0700);
 760                 if (ret < 0)
 761                         goto mkdir_error;
 762
 763                 ASSERT(d_backing_inode(subdir));
 764
 765                 _debug("mkdir -> %p{%p{ino=%lu}}",
 766                        subdir,
 767                        d_backing_inode(subdir),
 768                        d_backing_inode(subdir)->i_ino);
 769         }
 770
 771         mutex_unlock(&d_inode(dir)->i_mutex);
 772
 773         /* we need to make sure the subdir is a directory */
 774         ASSERT(d_backing_inode(subdir));
 775
 776         if (!d_can_lookup(subdir)) {
 777                 pr_err("%s is not a directory\n", dirname);
 778                 ret = -EIO;
 779                 goto check_error;
 780         }
 781
 782         ret = -EPERM;
 783         if (!d_backing_inode(subdir)->i_op->setxattr ||
 784             !d_backing_inode(subdir)->i_op->getxattr ||
 785             !d_backing_inode(subdir)->i_op->lookup ||
 786             !d_backing_inode(subdir)->i_op->mkdir ||
 787             !d_backing_inode(subdir)->i_op->create ||
 788             (!d_backing_inode(subdir)->i_op->rename &&
 789              !d_backing_inode(subdir)->i_op->rename2) ||
 790             !d_backing_inode(subdir)->i_op->rmdir ||
 791             !d_backing_inode(subdir)->i_op->unlink)
 792                 goto check_error;
 793
 794         _leave(" = [%lu]", d_backing_inode(subdir)->i_ino);
 795         return subdir;
 796
 797 check_error:
 798         dput(subdir);
 799         _leave(" = %d [check]", ret);
 800         return ERR_PTR(ret);
 801
 802 mkdir_error:
 803         mutex_unlock(&d_inode(dir)->i_mutex);
 804         dput(subdir);
 805         pr_err("mkdir %s failed with error %d\n", dirname, ret);
 806         return ERR_PTR(ret);
 807
 808 lookup_error:
 809         mutex_unlock(&d_inode(dir)->i_mutex);
 810         ret = PTR_ERR(subdir);
 811         pr_err("Lookup %s failed with error %d\n", dirname, ret);
 812         return ERR_PTR(ret);
 813
 814 nomem_d_alloc:
 815         mutex_unlock(&d_inode(dir)->i_mutex);
 816         _leave(" = -ENOMEM");
 817         return ERR_PTR(-ENOMEM);
 818 }
 819
 820 /*
 821  * find out if an object is in use or not
 822  * - if finds object and it's not in use:
 823  *   - returns a pointer to the object and a reference on it
 824  *   - returns with the directory locked
 825  */
 826 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
 827                                               struct dentry *dir,
 828                                               char *filename)
 829 {
 830         struct cachefiles_object *object;
 831         struct rb_node *_n;
 832         struct dentry *victim;
 833         unsigned long start;
 834         int ret;
 835
 836         //_enter(",%pd/,%s",
 837         //       dir, filename);
 838
 839         /* look up the victim */
 840         mutex_lock_nested(&d_inode(dir)->i_mutex, I_MUTEX_PARENT);
 841
 842         start = jiffies;
 843         victim = lookup_one_len(filename, dir, strlen(filename));
 844         cachefiles_hist(cachefiles_lookup_histogram, start);
 845         if (IS_ERR(victim))
 846                 goto lookup_error;
 847
 848         //_debug("victim -> %p %s",
 849         //       victim, d_backing_inode(victim) ? "positive" : "negative");
 850
 851         /* if the object is no longer there then we probably retired the object
 852          * at the netfs's request whilst the cull was in progress
 853          */
 854         if (d_is_negative(victim)) {
 855                 mutex_unlock(&d_inode(dir)->i_mutex);
 856                 dput(victim);
 857                 _leave(" = -ENOENT [absent]");
 858                 return ERR_PTR(-ENOENT);
 859         }
 860
 861         /* check to see if we're using this object */
 862         read_lock(&cache->active_lock);
 863
 864         _n = cache->active_nodes.rb_node;
 865
 866         while (_n) {
 867                 object = rb_entry(_n, struct cachefiles_object, active_node);
 868
 869                 if (object->dentry > victim)
 870                         _n = _n->rb_left;
 871                 else if (object->dentry < victim)
 872                         _n = _n->rb_right;
 873                 else
 874                         goto object_in_use;
 875         }
 876
 877         read_unlock(&cache->active_lock);
 878
 879         //_leave(" = %p", victim);
 880         return victim;
 881
 882 object_in_use:
 883         read_unlock(&cache->active_lock);
 884         mutex_unlock(&d_inode(dir)->i_mutex);
 885         dput(victim);
 886         //_leave(" = -EBUSY [in use]");
 887         return ERR_PTR(-EBUSY);
 888
 889 lookup_error:
 890         mutex_unlock(&d_inode(dir)->i_mutex);
 891         ret = PTR_ERR(victim);
 892         if (ret == -ENOENT) {
 893                 /* file or dir now absent - probably retired by netfs */
 894                 _leave(" = -ESTALE [absent]");
 895                 return ERR_PTR(-ESTALE);
 896         }
 897
 898         if (ret == -EIO) {
 899                 cachefiles_io_error(cache, "Lookup failed");
 900         } else if (ret != -ENOMEM) {
 901                 pr_err("Internal error: %d\n", ret);
 902                 ret = -EIO;
 903         }
 904
 905         _leave(" = %d", ret);
 906         return ERR_PTR(ret);
 907 }
 908
 909 /*
 910  * cull an object if it's not in use
 911  * - called only by cache manager daemon
 912  */
 913 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
 914                     char *filename)
 915 {
 916         struct dentry *victim;
 917         int ret;
 918
 919         _enter(",%pd/,%s", dir, filename);
 920
 921         victim = cachefiles_check_active(cache, dir, filename);
 922         if (IS_ERR(victim))
 923                 return PTR_ERR(victim);
 924
 925         _debug("victim -> %p %s",
 926                victim, d_backing_inode(victim) ? "positive" : "negative");
 927
 928         /* okay... the victim is not being used so we can cull it
 929          * - start by marking it as stale
 930          */
 931         _debug("victim is cullable");
 932
 933         ret = cachefiles_remove_object_xattr(cache, victim);
 934         if (ret < 0)
 935                 goto error_unlock;
 936
 937         /*  actually remove the victim (drops the dir mutex) */
 938         _debug("bury");
 939
 940         ret = cachefiles_bury_object(cache, dir, victim, false,
 941                                      FSCACHE_OBJECT_WAS_CULLED);
 942         if (ret < 0)
 943                 goto error;
 944
 945         dput(victim);
 946         _leave(" = 0");
 947         return 0;
 948
 949 error_unlock:
 950         mutex_unlock(&d_inode(dir)->i_mutex);
 951 error:
 952         dput(victim);
 953         if (ret == -ENOENT) {
 954                 /* file or dir now absent - probably retired by netfs */
 955                 _leave(" = -ESTALE [absent]");
 956                 return -ESTALE;
 957         }
 958
 959         if (ret != -ENOMEM) {
 960                 pr_err("Internal error: %d\n", ret);
 961                 ret = -EIO;
 962         }
 963
 964         _leave(" = %d", ret);
 965         return ret;
 966 }
 967
 968 /*
 969  * find out if an object is in use or not
 970  * - called only by cache manager daemon
 971  * - returns -EBUSY or 0 to indicate whether an object is in use or not
 972  */
 973 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
 974                             char *filename)
 975 {
 976         struct dentry *victim;
 977
 978         //_enter(",%pd/,%s",
 979         //       dir, filename);
 980
 981         victim = cachefiles_check_active(cache, dir, filename);
 982         if (IS_ERR(victim))
 983                 return PTR_ERR(victim);
 984
 985         mutex_unlock(&d_inode(dir)->i_mutex);
 986         dput(victim);
 987         //_leave(" = 0");
 988         return 0;
 989 }