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         printk(KERN_ERR "%sobject: OBJ%x\n",
  39                prefix, object->fscache.debug_id);
  40         printk(KERN_ERR "%sobjstate=%s fl=%lx wbusy=%x ev=%lx[%lx]\n",
  41                prefix, fscache_object_states[object->fscache.state],
  42                object->fscache.flags, work_busy(&object->fscache.work),
  43                object->fscache.events,
  44                object->fscache.event_mask & FSCACHE_OBJECT_EVENTS_MASK);
  45         printk(KERN_ERR "%sops=%u inp=%u exc=%u\n",
  46                prefix, object->fscache.n_ops, object->fscache.n_in_progress,
  47                object->fscache.n_exclusive);
  48         printk(KERN_ERR "%sparent=%p\n",
  49                prefix, object->fscache.parent);
  50
  51         spin_lock(&object->fscache.lock);
  52         cookie = object->fscache.cookie;
  53         if (cookie) {
  54                 printk(KERN_ERR "%scookie=%p [pr=%p nd=%p fl=%lx]\n",
  55                        prefix,
  56                        object->fscache.cookie,
  57                        object->fscache.cookie->parent,
  58                        object->fscache.cookie->netfs_data,
  59                        object->fscache.cookie->flags);
  60                 if (keybuf)
  61                         keylen = cookie->def->get_key(cookie->netfs_data, keybuf,
  62                                                       CACHEFILES_KEYBUF_SIZE);
  63                 else
  64                         keylen = 0;
  65         } else {
  66                 printk(KERN_ERR "%scookie=NULL\n", prefix);
  67                 keylen = 0;
  68         }
  69         spin_unlock(&object->fscache.lock);
  70
  71         if (keylen) {
  72                 printk(KERN_ERR "%skey=[%u] '", prefix, keylen);
  73                 for (loop = 0; loop < keylen; loop++)
  74                         printk("%02x", keybuf[loop]);
  75                 printk("'\n");
  76         }
  77 }
  78
  79 /*
  80  * dump debugging info about a pair of objects
  81  */
  82 static noinline void cachefiles_printk_object(struct cachefiles_object *object,
  83                                               struct cachefiles_object *xobject)
  84 {
  85         u8 *keybuf;
  86
  87         keybuf = kmalloc(CACHEFILES_KEYBUF_SIZE, GFP_NOIO);
  88         if (object)
  89                 __cachefiles_printk_object(object, "", keybuf);
  90         if (xobject)
  91                 __cachefiles_printk_object(xobject, "x", keybuf);
  92         kfree(keybuf);
  93 }
  94
  95 /*
  96  * mark the owner of a dentry, if there is one, to indicate that that dentry
  97  * has been preemptively deleted
  98  * - the caller must hold the i_mutex on the dentry's parent as required to
  99  *   call vfs_unlink(), vfs_rmdir() or vfs_rename()
 100  */
 101 static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
 102                                           struct dentry *dentry)
 103 {
 104         struct cachefiles_object *object;
 105         struct rb_node *p;
 106
 107         _enter(",'%*.*s'",
 108                dentry->d_name.len, dentry->d_name.len, dentry->d_name.name);
 109
 110         write_lock(&cache->active_lock);
 111
 112         p = cache->active_nodes.rb_node;
 113         while (p) {
 114                 object = rb_entry(p, struct cachefiles_object, active_node);
 115                 if (object->dentry > dentry)
 116                         p = p->rb_left;
 117                 else if (object->dentry < dentry)
 118                         p = p->rb_right;
 119                 else
 120                         goto found_dentry;
 121         }
 122
 123         write_unlock(&cache->active_lock);
 124         _leave(" [no owner]");
 125         return;
 126
 127         /* found the dentry for  */
 128 found_dentry:
 129         kdebug("preemptive burial: OBJ%x [%s] %p",
 130                object->fscache.debug_id,
 131                fscache_object_states[object->fscache.state],
 132                dentry);
 133
 134         if (object->fscache.state < FSCACHE_OBJECT_DYING) {
 135                 printk(KERN_ERR "\n");
 136                 printk(KERN_ERR "CacheFiles: Error:"
 137                        " Can't preemptively bury live object\n");
 138                 cachefiles_printk_object(object, NULL);
 139         } else if (test_and_set_bit(CACHEFILES_OBJECT_BURIED, &object->flags)) {
 140                 printk(KERN_ERR "CacheFiles: Error:"
 141                        " Object already preemptively buried\n");
 142         }
 143
 144         write_unlock(&cache->active_lock);
 145         _leave(" [owner marked]");
 146 }
 147
 148 /*
 149  * record the fact that an object is now active
 150  */
 151 static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
 152                                          struct cachefiles_object *object)
 153 {
 154         struct cachefiles_object *xobject;
 155         struct rb_node **_p, *_parent = NULL;
 156         struct dentry *dentry;
 157
 158         _enter(",%p", object);
 159
 160 try_again:
 161         write_lock(&cache->active_lock);
 162
 163         if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
 164                 printk(KERN_ERR "CacheFiles: Error: Object already active\n");
 165                 cachefiles_printk_object(object, NULL);
 166                 BUG();
 167         }
 168
 169         dentry = object->dentry;
 170         _p = &cache->active_nodes.rb_node;
 171         while (*_p) {
 172                 _parent = *_p;
 173                 xobject = rb_entry(_parent,
 174                                    struct cachefiles_object, active_node);
 175
 176                 ASSERT(xobject != object);
 177
 178                 if (xobject->dentry > dentry)
 179                         _p = &(*_p)->rb_left;
 180                 else if (xobject->dentry < dentry)
 181                         _p = &(*_p)->rb_right;
 182                 else
 183                         goto wait_for_old_object;
 184         }
 185
 186         rb_link_node(&object->active_node, _parent, _p);
 187         rb_insert_color(&object->active_node, &cache->active_nodes);
 188
 189         write_unlock(&cache->active_lock);
 190         _leave(" = 0");
 191         return 0;
 192
 193         /* an old object from a previous incarnation is hogging the slot - we
 194          * need to wait for it to be destroyed */
 195 wait_for_old_object:
 196         if (xobject->fscache.state < FSCACHE_OBJECT_DYING) {
 197                 printk(KERN_ERR "\n");
 198                 printk(KERN_ERR "CacheFiles: Error:"
 199                        " Unexpected object collision\n");
 200                 cachefiles_printk_object(object, xobject);
 201                 BUG();
 202         }
 203         atomic_inc(&xobject->usage);
 204         write_unlock(&cache->active_lock);
 205
 206         if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 207                 wait_queue_head_t *wq;
 208
 209                 signed long timeout = 60 * HZ;
 210                 wait_queue_t wait;
 211                 bool requeue;
 212
 213                 /* if the object we're waiting for is queued for processing,
 214                  * then just put ourselves on the queue behind it */
 215                 if (work_pending(&xobject->fscache.work)) {
 216                         _debug("queue OBJ%x behind OBJ%x immediately",
 217                                object->fscache.debug_id,
 218                                xobject->fscache.debug_id);
 219                         goto requeue;
 220                 }
 221
 222                 /* otherwise we sleep until either the object we're waiting for
 223                  * is done, or the fscache_object is congested */
 224                 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
 225                 init_wait(&wait);
 226                 requeue = false;
 227                 do {
 228                         prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
 229                         if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
 230                                 break;
 231
 232                         requeue = fscache_object_sleep_till_congested(&timeout);
 233                 } while (timeout > 0 && !requeue);
 234                 finish_wait(wq, &wait);
 235
 236                 if (requeue &&
 237                     test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 238                         _debug("queue OBJ%x behind OBJ%x after wait",
 239                                object->fscache.debug_id,
 240                                xobject->fscache.debug_id);
 241                         goto requeue;
 242                 }
 243
 244                 if (timeout <= 0) {
 245                         printk(KERN_ERR "\n");
 246                         printk(KERN_ERR "CacheFiles: Error: Overlong"
 247                                " wait for old active object to go away\n");
 248                         cachefiles_printk_object(object, xobject);
 249                         goto requeue;
 250                 }
 251         }
 252
 253         ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
 254
 255         cache->cache.ops->put_object(&xobject->fscache);
 256         goto try_again;
 257
 258 requeue:
 259         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 260         cache->cache.ops->put_object(&xobject->fscache);
 261         _leave(" = -ETIMEDOUT");
 262         return -ETIMEDOUT;
 263 }
 264
 265 /*
 266  * delete an object representation from the cache
 267  * - file backed objects are unlinked
 268  * - directory backed objects are stuffed into the graveyard for userspace to
 269  *   delete
 270  * - unlocks the directory mutex
 271  */
 272 static int cachefiles_bury_object(struct cachefiles_cache *cache,
 273                                   struct dentry *dir,
 274                                   struct dentry *rep,
 275                                   bool preemptive)
 276 {
 277         struct dentry *grave, *trap;
 278         struct path path, path_to_graveyard;
 279         char nbuffer[8 + 8 + 1];
 280         int ret;
 281
 282         _enter(",'%*.*s','%*.*s'",
 283                dir->d_name.len, dir->d_name.len, dir->d_name.name,
 284                rep->d_name.len, rep->d_name.len, rep->d_name.name);
 285
 286         _debug("remove %p from %p", rep, dir);
 287
 288         /* non-directories can just be unlinked */
 289         if (!S_ISDIR(rep->d_inode->i_mode)) {
 290                 _debug("unlink stale object");
 291
 292                 path.mnt = cache->mnt;
 293                 path.dentry = dir;
 294                 ret = security_path_unlink(&path, rep);
 295                 if (ret < 0) {
 296                         cachefiles_io_error(cache, "Unlink security error");
 297                 } else {
 298                         ret = vfs_unlink(dir->d_inode, rep);
 299
 300                         if (preemptive)
 301                                 cachefiles_mark_object_buried(cache, rep);
 302                 }
 303
 304                 mutex_unlock(&dir->d_inode->i_mutex);
 305
 306                 if (ret == -EIO)
 307                         cachefiles_io_error(cache, "Unlink failed");
 308
 309                 _leave(" = %d", ret);
 310                 return ret;
 311         }
 312
 313         /* directories have to be moved to the graveyard */
 314         _debug("move stale object to graveyard");
 315         mutex_unlock(&dir->d_inode->i_mutex);
 316
 317 try_again:
 318         /* first step is to make up a grave dentry in the graveyard */
 319         sprintf(nbuffer, "%08x%08x",
 320                 (uint32_t) get_seconds(),
 321                 (uint32_t) atomic_inc_return(&cache->gravecounter));
 322
 323         /* do the multiway lock magic */
 324         trap = lock_rename(cache->graveyard, dir);
 325
 326         /* do some checks before getting the grave dentry */
 327         if (rep->d_parent != dir) {
 328                 /* the entry was probably culled when we dropped the parent dir
 329                  * lock */
 330                 unlock_rename(cache->graveyard, dir);
 331                 _leave(" = 0 [culled?]");
 332                 return 0;
 333         }
 334
 335         if (!S_ISDIR(cache->graveyard->d_inode->i_mode)) {
 336                 unlock_rename(cache->graveyard, dir);
 337                 cachefiles_io_error(cache, "Graveyard no longer a directory");
 338                 return -EIO;
 339         }
 340
 341         if (trap == rep) {
 342                 unlock_rename(cache->graveyard, dir);
 343                 cachefiles_io_error(cache, "May not make directory loop");
 344                 return -EIO;
 345         }
 346
 347         if (d_mountpoint(rep)) {
 348                 unlock_rename(cache->graveyard, dir);
 349                 cachefiles_io_error(cache, "Mountpoint in cache");
 350                 return -EIO;
 351         }
 352
 353         grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
 354         if (IS_ERR(grave)) {
 355                 unlock_rename(cache->graveyard, dir);
 356
 357                 if (PTR_ERR(grave) == -ENOMEM) {
 358                         _leave(" = -ENOMEM");
 359                         return -ENOMEM;
 360                 }
 361
 362                 cachefiles_io_error(cache, "Lookup error %ld",
 363                                     PTR_ERR(grave));
 364                 return -EIO;
 365         }
 366
 367         if (grave->d_inode) {
 368                 unlock_rename(cache->graveyard, dir);
 369                 dput(grave);
 370                 grave = NULL;
 371                 cond_resched();
 372                 goto try_again;
 373         }
 374
 375         if (d_mountpoint(grave)) {
 376                 unlock_rename(cache->graveyard, dir);
 377                 dput(grave);
 378                 cachefiles_io_error(cache, "Mountpoint in graveyard");
 379                 return -EIO;
 380         }
 381
 382         /* target should not be an ancestor of source */
 383         if (trap == grave) {
 384                 unlock_rename(cache->graveyard, dir);
 385                 dput(grave);
 386                 cachefiles_io_error(cache, "May not make directory loop");
 387                 return -EIO;
 388         }
 389
 390         /* attempt the rename */
 391         path.mnt = cache->mnt;
 392         path.dentry = dir;
 393         path_to_graveyard.mnt = cache->mnt;
 394         path_to_graveyard.dentry = cache->graveyard;
 395         ret = security_path_rename(&path, rep, &path_to_graveyard, grave);
 396         if (ret < 0) {
 397                 cachefiles_io_error(cache, "Rename security error %d", ret);
 398         } else {
 399                 ret = vfs_rename(dir->d_inode, rep,
 400                                  cache->graveyard->d_inode, grave);
 401                 if (ret != 0 && ret != -ENOMEM)
 402                         cachefiles_io_error(cache,
 403                                             "Rename failed with error %d", ret);
 404
 405                 if (preemptive)
 406                         cachefiles_mark_object_buried(cache, rep);
 407         }
 408
 409         unlock_rename(cache->graveyard, dir);
 410         dput(grave);
 411         _leave(" = 0");
 412         return 0;
 413 }
 414
 415 /*
 416  * delete an object representation from the cache
 417  */
 418 int cachefiles_delete_object(struct cachefiles_cache *cache,
 419                              struct cachefiles_object *object)
 420 {
 421         struct dentry *dir;
 422         int ret;
 423
 424         _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
 425
 426         ASSERT(object->dentry);
 427         ASSERT(object->dentry->d_inode);
 428         ASSERT(object->dentry->d_parent);
 429
 430         dir = dget_parent(object->dentry);
 431
 432         mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 433
 434         if (test_bit(CACHEFILES_OBJECT_BURIED, &object->flags)) {
 435                 /* object allocation for the same key preemptively deleted this
 436                  * object's file so that it could create its own file */
 437                 _debug("object preemptively buried");
 438                 mutex_unlock(&dir->d_inode->i_mutex);
 439                 ret = 0;
 440         } else {
 441                 /* we need to check that our parent is _still_ our parent - it
 442                  * may have been renamed */
 443                 if (dir == object->dentry->d_parent) {
 444                         ret = cachefiles_bury_object(cache, dir,
 445                                                      object->dentry, false);
 446                 } else {
 447                         /* it got moved, presumably by cachefilesd culling it,
 448                          * so it's no longer in the key path and we can ignore
 449                          * it */
 450                         mutex_unlock(&dir->d_inode->i_mutex);
 451                         ret = 0;
 452                 }
 453         }
 454
 455         dput(dir);
 456         _leave(" = %d", ret);
 457         return ret;
 458 }
 459
 460 /*
 461  * walk from the parent object to the child object through the backing
 462  * filesystem, creating directories as we go
 463  */
 464 int cachefiles_walk_to_object(struct cachefiles_object *parent,
 465                               struct cachefiles_object *object,
 466                               const char *key,
 467                               struct cachefiles_xattr *auxdata)
 468 {
 469         struct cachefiles_cache *cache;
 470         struct dentry *dir, *next = NULL;
 471         struct path path;
 472         unsigned long start;
 473         const char *name;
 474         int ret, nlen;
 475
 476         _enter("OBJ%x{%p},OBJ%x,%s,",
 477                parent->fscache.debug_id, parent->dentry,
 478                object->fscache.debug_id, key);
 479
 480         cache = container_of(parent->fscache.cache,
 481                              struct cachefiles_cache, cache);
 482         path.mnt = cache->mnt;
 483
 484         ASSERT(parent->dentry);
 485         ASSERT(parent->dentry->d_inode);
 486
 487         if (!(S_ISDIR(parent->dentry->d_inode->i_mode))) {
 488                 // TODO: convert file to dir
 489                 _leave("looking up in none directory");
 490                 return -ENOBUFS;
 491         }
 492
 493         dir = dget(parent->dentry);
 494
 495 advance:
 496         /* attempt to transit the first directory component */
 497         name = key;
 498         nlen = strlen(key);
 499
 500         /* key ends in a double NUL */
 501         key = key + nlen + 1;
 502         if (!*key)
 503                 key = NULL;
 504
 505 lookup_again:
 506         /* search the current directory for the element name */
 507         _debug("lookup '%s'", name);
 508
 509         mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 510
 511         start = jiffies;
 512         next = lookup_one_len(name, dir, nlen);
 513         cachefiles_hist(cachefiles_lookup_histogram, start);
 514         if (IS_ERR(next))
 515                 goto lookup_error;
 516
 517         _debug("next -> %p %s", next, next->d_inode ? "positive" : "negative");
 518
 519         if (!key)
 520                 object->new = !next->d_inode;
 521
 522         /* if this element of the path doesn't exist, then the lookup phase
 523          * failed, and we can release any readers in the certain knowledge that
 524          * there's nothing for them to actually read */
 525         if (!next->d_inode)
 526                 fscache_object_lookup_negative(&object->fscache);
 527
 528         /* we need to create the object if it's negative */
 529         if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
 530                 /* index objects and intervening tree levels must be subdirs */
 531                 if (!next->d_inode) {
 532                         ret = cachefiles_has_space(cache, 1, 0);
 533                         if (ret < 0)
 534                                 goto create_error;
 535
 536                         path.dentry = dir;
 537                         ret = security_path_mkdir(&path, next, 0);
 538                         if (ret < 0)
 539                                 goto create_error;
 540                         start = jiffies;
 541                         ret = vfs_mkdir(dir->d_inode, next, 0);
 542                         cachefiles_hist(cachefiles_mkdir_histogram, start);
 543                         if (ret < 0)
 544                                 goto create_error;
 545
 546                         ASSERT(next->d_inode);
 547
 548                         _debug("mkdir -> %p{%p{ino=%lu}}",
 549                                next, next->d_inode, next->d_inode->i_ino);
 550
 551                 } else if (!S_ISDIR(next->d_inode->i_mode)) {
 552                         kerror("inode %lu is not a directory",
 553                                next->d_inode->i_ino);
 554                         ret = -ENOBUFS;
 555                         goto error;
 556                 }
 557
 558         } else {
 559                 /* non-index objects start out life as files */
 560                 if (!next->d_inode) {
 561                         ret = cachefiles_has_space(cache, 1, 0);
 562                         if (ret < 0)
 563                                 goto create_error;
 564
 565                         path.dentry = dir;
 566                         ret = security_path_mknod(&path, next, S_IFREG, 0);
 567                         if (ret < 0)
 568                                 goto create_error;
 569                         start = jiffies;
 570                         ret = vfs_create(dir->d_inode, next, S_IFREG, NULL);
 571                         cachefiles_hist(cachefiles_create_histogram, start);
 572                         if (ret < 0)
 573                                 goto create_error;
 574
 575                         ASSERT(next->d_inode);
 576
 577                         _debug("create -> %p{%p{ino=%lu}}",
 578                                next, next->d_inode, next->d_inode->i_ino);
 579
 580                 } else if (!S_ISDIR(next->d_inode->i_mode) &&
 581                            !S_ISREG(next->d_inode->i_mode)
 582                            ) {
 583                         kerror("inode %lu is not a file or directory",
 584                                next->d_inode->i_ino);
 585                         ret = -ENOBUFS;
 586                         goto error;
 587                 }
 588         }
 589
 590         /* process the next component */
 591         if (key) {
 592                 _debug("advance");
 593                 mutex_unlock(&dir->d_inode->i_mutex);
 594                 dput(dir);
 595                 dir = next;
 596                 next = NULL;
 597                 goto advance;
 598         }
 599
 600         /* we've found the object we were looking for */
 601         object->dentry = next;
 602
 603         /* if we've found that the terminal object exists, then we need to
 604          * check its attributes and delete it if it's out of date */
 605         if (!object->new) {
 606                 _debug("validate '%*.*s'",
 607                        next->d_name.len, next->d_name.len, next->d_name.name);
 608
 609                 ret = cachefiles_check_object_xattr(object, auxdata);
 610                 if (ret == -ESTALE) {
 611                         /* delete the object (the deleter drops the directory
 612                          * mutex) */
 613                         object->dentry = NULL;
 614
 615                         ret = cachefiles_bury_object(cache, dir, next, true);
 616                         dput(next);
 617                         next = NULL;
 618
 619                         if (ret < 0)
 620                                 goto delete_error;
 621
 622                         _debug("redo lookup");
 623                         goto lookup_again;
 624                 }
 625         }
 626
 627         /* note that we're now using this object */
 628         ret = cachefiles_mark_object_active(cache, object);
 629
 630         mutex_unlock(&dir->d_inode->i_mutex);
 631         dput(dir);
 632         dir = NULL;
 633
 634         if (ret == -ETIMEDOUT)
 635                 goto mark_active_timed_out;
 636
 637         _debug("=== OBTAINED_OBJECT ===");
 638
 639         if (object->new) {
 640                 /* attach data to a newly constructed terminal object */
 641                 ret = cachefiles_set_object_xattr(object, auxdata);
 642                 if (ret < 0)
 643                         goto check_error;
 644         } else {
 645                 /* always update the atime on an object we've just looked up
 646                  * (this is used to keep track of culling, and atimes are only
 647                  * updated by read, write and readdir but not lookup or
 648                  * open) */
 649                 path.dentry = next;
 650                 touch_atime(&path);
 651         }
 652
 653         /* open a file interface onto a data file */
 654         if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
 655                 if (S_ISREG(object->dentry->d_inode->i_mode)) {
 656                         const struct address_space_operations *aops;
 657
 658                         ret = -EPERM;
 659                         aops = object->dentry->d_inode->i_mapping->a_ops;
 660                         if (!aops->bmap)
 661                                 goto check_error;
 662
 663                         object->backer = object->dentry;
 664                 } else {
 665                         BUG(); // TODO: open file in data-class subdir
 666                 }
 667         }
 668
 669         object->new = 0;
 670         fscache_obtained_object(&object->fscache);
 671
 672         _leave(" = 0 [%lu]", object->dentry->d_inode->i_ino);
 673         return 0;
 674
 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(&dir->d_inode->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(&dir->d_inode->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, subdir->d_inode ? "positive" : "negative");
 745
 746         /* we need to create the subdir if it doesn't exist yet */
 747         if (!subdir->d_inode) {
 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(dir->d_inode, subdir, 0700);
 760                 if (ret < 0)
 761                         goto mkdir_error;
 762
 763                 ASSERT(subdir->d_inode);
 764
 765                 _debug("mkdir -> %p{%p{ino=%lu}}",
 766                        subdir,
 767                        subdir->d_inode,
 768                        subdir->d_inode->i_ino);
 769         }
 770
 771         mutex_unlock(&dir->d_inode->i_mutex);
 772
 773         /* we need to make sure the subdir is a directory */
 774         ASSERT(subdir->d_inode);
 775
 776         if (!S_ISDIR(subdir->d_inode->i_mode)) {
 777                 kerror("%s is not a directory", dirname);
 778                 ret = -EIO;
 779                 goto check_error;
 780         }
 781
 782         ret = -EPERM;
 783         if (!subdir->d_inode->i_op ||
 784             !subdir->d_inode->i_op->setxattr ||
 785             !subdir->d_inode->i_op->getxattr ||
 786             !subdir->d_inode->i_op->lookup ||
 787             !subdir->d_inode->i_op->mkdir ||
 788             !subdir->d_inode->i_op->create ||
 789             !subdir->d_inode->i_op->rename ||
 790             !subdir->d_inode->i_op->rmdir ||
 791             !subdir->d_inode->i_op->unlink)
 792                 goto check_error;
 793
 794         _leave(" = [%lu]", subdir->d_inode->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(&dir->d_inode->i_mutex);
 804         dput(subdir);
 805         kerror("mkdir %s failed with error %d", dirname, ret);
 806         return ERR_PTR(ret);
 807
 808 lookup_error:
 809         mutex_unlock(&dir->d_inode->i_mutex);
 810         ret = PTR_ERR(subdir);
 811         kerror("Lookup %s failed with error %d", dirname, ret);
 812         return ERR_PTR(ret);
 813
 814 nomem_d_alloc:
 815         mutex_unlock(&dir->d_inode->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(",%*.*s/,%s",
 837         //       dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 838
 839         /* look up the victim */
 840         mutex_lock_nested(&dir->d_inode->i_mutex, 1);
 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, victim->d_inode ? "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 (!victim->d_inode) {
 855                 mutex_unlock(&dir->d_inode->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(&dir->d_inode->i_mutex);
 885         dput(victim);
 886         //_leave(" = -EBUSY [in use]");
 887         return ERR_PTR(-EBUSY);
 888
 889 lookup_error:
 890         mutex_unlock(&dir->d_inode->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                 kerror("Internal error: %d", 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(",%*.*s/,%s",
 920                dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 921
 922         victim = cachefiles_check_active(cache, dir, filename);
 923         if (IS_ERR(victim))
 924                 return PTR_ERR(victim);
 925
 926         _debug("victim -> %p %s",
 927                victim, victim->d_inode ? "positive" : "negative");
 928
 929         /* okay... the victim is not being used so we can cull it
 930          * - start by marking it as stale
 931          */
 932         _debug("victim is cullable");
 933
 934         ret = cachefiles_remove_object_xattr(cache, victim);
 935         if (ret < 0)
 936                 goto error_unlock;
 937
 938         /*  actually remove the victim (drops the dir mutex) */
 939         _debug("bury");
 940
 941         ret = cachefiles_bury_object(cache, dir, victim, false);
 942         if (ret < 0)
 943                 goto error;
 944
 945         dput(victim);
 946         _leave(" = 0");
 947         return 0;
 948
 949 error_unlock:
 950         mutex_unlock(&dir->d_inode->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                 kerror("Internal error: %d", 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(",%*.*s/,%s",
 979         //       dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 980
 981         victim = cachefiles_check_active(cache, dir, filename);
 982         if (IS_ERR(victim))
 983                 return PTR_ERR(victim);
 984
 985         mutex_unlock(&dir->d_inode->i_mutex);
 986         dput(victim);
 987         //_leave(" = 0");
 988         return 0;
 989 }