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 ([email protected])
   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, object->fscache.event_mask);
  44         printk(KERN_ERR "%sops=%u inp=%u exc=%u\n",
  45                prefix, object->fscache.n_ops, object->fscache.n_in_progress,
  46                object->fscache.n_exclusive);
  47         printk(KERN_ERR "%sparent=%p\n",
  48                prefix, object->fscache.parent);
  49
  50         spin_lock(&object->fscache.lock);
  51         cookie = object->fscache.cookie;
  52         if (cookie) {
  53                 printk(KERN_ERR "%scookie=%p [pr=%p nd=%p fl=%lx]\n",
  54                        prefix,
  55                        object->fscache.cookie,
  56                        object->fscache.cookie->parent,
  57                        object->fscache.cookie->netfs_data,
  58                        object->fscache.cookie->flags);
  59                 if (keybuf)
  60                         keylen = cookie->def->get_key(cookie->netfs_data, keybuf,
  61                                                       CACHEFILES_KEYBUF_SIZE);
  62                 else
  63                         keylen = 0;
  64         } else {
  65                 printk(KERN_ERR "%scookie=NULL\n", prefix);
  66                 keylen = 0;
  67         }
  68         spin_unlock(&object->fscache.lock);
  69
  70         if (keylen) {
  71                 printk(KERN_ERR "%skey=[%u] '", prefix, keylen);
  72                 for (loop = 0; loop < keylen; loop++)
  73                         printk("%02x", keybuf[loop]);
  74                 printk("'\n");
  75         }
  76 }
  77
  78 /*
  79  * dump debugging info about a pair of objects
  80  */
  81 static noinline void cachefiles_printk_object(struct cachefiles_object *object,
  82                                               struct cachefiles_object *xobject)
  83 {
  84         u8 *keybuf;
  85
  86         keybuf = kmalloc(CACHEFILES_KEYBUF_SIZE, GFP_NOIO);
  87         if (object)
  88                 __cachefiles_printk_object(object, "", keybuf);
  89         if (xobject)
  90                 __cachefiles_printk_object(xobject, "x", keybuf);
  91         kfree(keybuf);
  92 }
  93
  94 /*
  95  * mark the owner of a dentry, if there is one, to indicate that that dentry
  96  * has been preemptively deleted
  97  * - the caller must hold the i_mutex on the dentry's parent as required to
  98  *   call vfs_unlink(), vfs_rmdir() or vfs_rename()
  99  */
 100 static void cachefiles_mark_object_buried(struct cachefiles_cache *cache,
 101                                           struct dentry *dentry)
 102 {
 103         struct cachefiles_object *object;
 104         struct rb_node *p;
 105
 106         _enter(",'%*.*s'",
 107                dentry->d_name.len, dentry->d_name.len, dentry->d_name.name);
 108
 109         write_lock(&cache->active_lock);
 110
 111         p = cache->active_nodes.rb_node;
 112         while (p) {
 113                 object = rb_entry(p, struct cachefiles_object, active_node);
 114                 if (object->dentry > dentry)
 115                         p = p->rb_left;
 116                 else if (object->dentry < dentry)
 117                         p = p->rb_right;
 118                 else
 119                         goto found_dentry;
 120         }
 121
 122         write_unlock(&cache->active_lock);
 123         _leave(" [no owner]");
 124         return;
 125
 126         /* found the dentry for  */
 127 found_dentry:
 128         kdebug("preemptive burial: OBJ%x [%s] %p",
 129                object->fscache.debug_id,
 130                fscache_object_states[object->fscache.state],
 131                dentry);
 132
 133         if (object->fscache.state < FSCACHE_OBJECT_DYING) {
 134                 printk(KERN_ERR "\n");
 135                 printk(KERN_ERR "CacheFiles: Error:"
 136                        " Can't preemptively bury live object\n");
 137                 cachefiles_printk_object(object, NULL);
 138         } else if (test_and_set_bit(CACHEFILES_OBJECT_BURIED, &object->flags)) {
 139                 printk(KERN_ERR "CacheFiles: Error:"
 140                        " Object already preemptively buried\n");
 141         }
 142
 143         write_unlock(&cache->active_lock);
 144         _leave(" [owner marked]");
 145 }
 146
 147 /*
 148  * record the fact that an object is now active
 149  */
 150 static int cachefiles_mark_object_active(struct cachefiles_cache *cache,
 151                                          struct cachefiles_object *object)
 152 {
 153         struct cachefiles_object *xobject;
 154         struct rb_node **_p, *_parent = NULL;
 155         struct dentry *dentry;
 156
 157         _enter(",%p", object);
 158
 159 try_again:
 160         write_lock(&cache->active_lock);
 161
 162         if (test_and_set_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
 163                 printk(KERN_ERR "CacheFiles: Error: Object already active\n");
 164                 cachefiles_printk_object(object, NULL);
 165                 BUG();
 166         }
 167
 168         dentry = object->dentry;
 169         _p = &cache->active_nodes.rb_node;
 170         while (*_p) {
 171                 _parent = *_p;
 172                 xobject = rb_entry(_parent,
 173                                    struct cachefiles_object, active_node);
 174
 175                 ASSERT(xobject != object);
 176
 177                 if (xobject->dentry > dentry)
 178                         _p = &(*_p)->rb_left;
 179                 else if (xobject->dentry < dentry)
 180                         _p = &(*_p)->rb_right;
 181                 else
 182                         goto wait_for_old_object;
 183         }
 184
 185         rb_link_node(&object->active_node, _parent, _p);
 186         rb_insert_color(&object->active_node, &cache->active_nodes);
 187
 188         write_unlock(&cache->active_lock);
 189         _leave(" = 0");
 190         return 0;
 191
 192         /* an old object from a previous incarnation is hogging the slot - we
 193          * need to wait for it to be destroyed */
 194 wait_for_old_object:
 195         if (xobject->fscache.state < FSCACHE_OBJECT_DYING) {
 196                 printk(KERN_ERR "\n");
 197                 printk(KERN_ERR "CacheFiles: Error:"
 198                        " Unexpected object collision\n");
 199                 cachefiles_printk_object(object, xobject);
 200                 BUG();
 201         }
 202         atomic_inc(&xobject->usage);
 203         write_unlock(&cache->active_lock);
 204
 205         if (test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 206                 wait_queue_head_t *wq;
 207
 208                 signed long timeout = 60 * HZ;
 209                 wait_queue_t wait;
 210                 bool requeue;
 211
 212                 /* if the object we're waiting for is queued for processing,
 213                  * then just put ourselves on the queue behind it */
 214                 if (work_pending(&xobject->fscache.work)) {
 215                         _debug("queue OBJ%x behind OBJ%x immediately",
 216                                object->fscache.debug_id,
 217                                xobject->fscache.debug_id);
 218                         goto requeue;
 219                 }
 220
 221                 /* otherwise we sleep until either the object we're waiting for
 222                  * is done, or the fscache_object is congested */
 223                 wq = bit_waitqueue(&xobject->flags, CACHEFILES_OBJECT_ACTIVE);
 224                 init_wait(&wait);
 225                 requeue = false;
 226                 do {
 227                         prepare_to_wait(wq, &wait, TASK_UNINTERRUPTIBLE);
 228                         if (!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags))
 229                                 break;
 230
 231                         requeue = fscache_object_sleep_till_congested(&timeout);
 232                 } while (timeout > 0 && !requeue);
 233                 finish_wait(wq, &wait);
 234
 235                 if (requeue &&
 236                     test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags)) {
 237                         _debug("queue OBJ%x behind OBJ%x after wait",
 238                                object->fscache.debug_id,
 239                                xobject->fscache.debug_id);
 240                         goto requeue;
 241                 }
 242
 243                 if (timeout <= 0) {
 244                         printk(KERN_ERR "\n");
 245                         printk(KERN_ERR "CacheFiles: Error: Overlong"
 246                                " wait for old active object to go away\n");
 247                         cachefiles_printk_object(object, xobject);
 248                         goto requeue;
 249                 }
 250         }
 251
 252         ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &xobject->flags));
 253
 254         cache->cache.ops->put_object(&xobject->fscache);
 255         goto try_again;
 256
 257 requeue:
 258         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 259         cache->cache.ops->put_object(&xobject->fscache);
 260         _leave(" = -ETIMEDOUT");
 261         return -ETIMEDOUT;
 262 }
 263
 264 /*
 265  * delete an object representation from the cache
 266  * - file backed objects are unlinked
 267  * - directory backed objects are stuffed into the graveyard for userspace to
 268  *   delete
 269  * - unlocks the directory mutex
 270  */
 271 static int cachefiles_bury_object(struct cachefiles_cache *cache,
 272                                   struct dentry *dir,
 273                                   struct dentry *rep,
 274                                   bool preemptive)
 275 {
 276         struct dentry *grave, *trap;
 277         struct path path, path_to_graveyard;
 278         char nbuffer[8 + 8 + 1];
 279         int ret;
 280
 281         _enter(",'%*.*s','%*.*s'",
 282                dir->d_name.len, dir->d_name.len, dir->d_name.name,
 283                rep->d_name.len, rep->d_name.len, rep->d_name.name);
 284
 285         _debug("remove %p from %p", rep, dir);
 286
 287         /* non-directories can just be unlinked */
 288         if (!S_ISDIR(rep->d_inode->i_mode)) {
 289                 _debug("unlink stale object");
 290
 291                 path.mnt = cache->mnt;
 292                 path.dentry = dir;
 293                 ret = security_path_unlink(&path, rep);
 294                 if (ret < 0) {
 295                         cachefiles_io_error(cache, "Unlink security error");
 296                 } else {
 297                         ret = vfs_unlink(dir->d_inode, rep);
 298
 299                         if (preemptive)
 300                                 cachefiles_mark_object_buried(cache, rep);
 301                 }
 302
 303                 mutex_unlock(&dir->d_inode->i_mutex);
 304
 305                 if (ret == -EIO)
 306                         cachefiles_io_error(cache, "Unlink failed");
 307
 308                 _leave(" = %d", ret);
 309                 return ret;
 310         }
 311
 312         /* directories have to be moved to the graveyard */
 313         _debug("move stale object to graveyard");
 314         mutex_unlock(&dir->d_inode->i_mutex);
 315
 316 try_again:
 317         /* first step is to make up a grave dentry in the graveyard */
 318         sprintf(nbuffer, "%08x%08x",
 319                 (uint32_t) get_seconds(),
 320                 (uint32_t) atomic_inc_return(&cache->gravecounter));
 321
 322         /* do the multiway lock magic */
 323         trap = lock_rename(cache->graveyard, dir);
 324
 325         /* do some checks before getting the grave dentry */
 326         if (rep->d_parent != dir) {
 327                 /* the entry was probably culled when we dropped the parent dir
 328                  * lock */
 329                 unlock_rename(cache->graveyard, dir);
 330                 _leave(" = 0 [culled?]");
 331                 return 0;
 332         }
 333
 334         if (!S_ISDIR(cache->graveyard->d_inode->i_mode)) {
 335                 unlock_rename(cache->graveyard, dir);
 336                 cachefiles_io_error(cache, "Graveyard no longer a directory");
 337                 return -EIO;
 338         }
 339
 340         if (trap == rep) {
 341                 unlock_rename(cache->graveyard, dir);
 342                 cachefiles_io_error(cache, "May not make directory loop");
 343                 return -EIO;
 344         }
 345
 346         if (d_mountpoint(rep)) {
 347                 unlock_rename(cache->graveyard, dir);
 348                 cachefiles_io_error(cache, "Mountpoint in cache");
 349                 return -EIO;
 350         }
 351
 352         grave = lookup_one_len(nbuffer, cache->graveyard, strlen(nbuffer));
 353         if (IS_ERR(grave)) {
 354                 unlock_rename(cache->graveyard, dir);
 355
 356                 if (PTR_ERR(grave) == -ENOMEM) {
 357                         _leave(" = -ENOMEM");
 358                         return -ENOMEM;
 359                 }
 360
 361                 cachefiles_io_error(cache, "Lookup error %ld",
 362                                     PTR_ERR(grave));
 363                 return -EIO;
 364         }
 365
 366         if (grave->d_inode) {
 367                 unlock_rename(cache->graveyard, dir);
 368                 dput(grave);
 369                 grave = NULL;
 370                 cond_resched();
 371                 goto try_again;
 372         }
 373
 374         if (d_mountpoint(grave)) {
 375                 unlock_rename(cache->graveyard, dir);
 376                 dput(grave);
 377                 cachefiles_io_error(cache, "Mountpoint in graveyard");
 378                 return -EIO;
 379         }
 380
 381         /* target should not be an ancestor of source */
 382         if (trap == grave) {
 383                 unlock_rename(cache->graveyard, dir);
 384                 dput(grave);
 385                 cachefiles_io_error(cache, "May not make directory loop");
 386                 return -EIO;
 387         }
 388
 389         /* attempt the rename */
 390         path.mnt = cache->mnt;
 391         path.dentry = dir;
 392         path_to_graveyard.mnt = cache->mnt;
 393         path_to_graveyard.dentry = cache->graveyard;
 394         ret = security_path_rename(&path, rep, &path_to_graveyard, grave);
 395         if (ret < 0) {
 396                 cachefiles_io_error(cache, "Rename security error %d", ret);
 397         } else {
 398                 ret = vfs_rename(dir->d_inode, rep,
 399                                  cache->graveyard->d_inode, grave);
 400                 if (ret != 0 && ret != -ENOMEM)
 401                         cachefiles_io_error(cache,
 402                                             "Rename failed with error %d", ret);
 403
 404                 if (preemptive)
 405                         cachefiles_mark_object_buried(cache, rep);
 406         }
 407
 408         unlock_rename(cache->graveyard, dir);
 409         dput(grave);
 410         _leave(" = 0");
 411         return 0;
 412 }
 413
 414 /*
 415  * delete an object representation from the cache
 416  */
 417 int cachefiles_delete_object(struct cachefiles_cache *cache,
 418                              struct cachefiles_object *object)
 419 {
 420         struct dentry *dir;
 421         int ret;
 422
 423         _enter(",OBJ%x{%p}", object->fscache.debug_id, object->dentry);
 424
 425         ASSERT(object->dentry);
 426         ASSERT(object->dentry->d_inode);
 427         ASSERT(object->dentry->d_parent);
 428
 429         dir = dget_parent(object->dentry);
 430
 431         mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 432
 433         if (test_bit(CACHEFILES_OBJECT_BURIED, &object->flags)) {
 434                 /* object allocation for the same key preemptively deleted this
 435                  * object's file so that it could create its own file */
 436                 _debug("object preemptively buried");
 437                 mutex_unlock(&dir->d_inode->i_mutex);
 438                 ret = 0;
 439         } else {
 440                 /* we need to check that our parent is _still_ our parent - it
 441                  * may have been renamed */
 442                 if (dir == object->dentry->d_parent) {
 443                         ret = cachefiles_bury_object(cache, dir,
 444                                                      object->dentry, false);
 445                 } else {
 446                         /* it got moved, presumably by cachefilesd culling it,
 447                          * so it's no longer in the key path and we can ignore
 448                          * it */
 449                         mutex_unlock(&dir->d_inode->i_mutex);
 450                         ret = 0;
 451                 }
 452         }
 453
 454         dput(dir);
 455         _leave(" = %d", ret);
 456         return ret;
 457 }
 458
 459 /*
 460  * walk from the parent object to the child object through the backing
 461  * filesystem, creating directories as we go
 462  */
 463 int cachefiles_walk_to_object(struct cachefiles_object *parent,
 464                               struct cachefiles_object *object,
 465                               const char *key,
 466                               struct cachefiles_xattr *auxdata)
 467 {
 468         struct cachefiles_cache *cache;
 469         struct dentry *dir, *next = NULL;
 470         struct path path;
 471         unsigned long start;
 472         const char *name;
 473         int ret, nlen;
 474
 475         _enter("OBJ%x{%p},OBJ%x,%s,",
 476                parent->fscache.debug_id, parent->dentry,
 477                object->fscache.debug_id, key);
 478
 479         cache = container_of(parent->fscache.cache,
 480                              struct cachefiles_cache, cache);
 481         path.mnt = cache->mnt;
 482
 483         ASSERT(parent->dentry);
 484         ASSERT(parent->dentry->d_inode);
 485
 486         if (!(S_ISDIR(parent->dentry->d_inode->i_mode))) {
 487                 // TODO: convert file to dir
 488                 _leave("looking up in none directory");
 489                 return -ENOBUFS;
 490         }
 491
 492         dir = dget(parent->dentry);
 493
 494 advance:
 495         /* attempt to transit the first directory component */
 496         name = key;
 497         nlen = strlen(key);
 498
 499         /* key ends in a double NUL */
 500         key = key + nlen + 1;
 501         if (!*key)
 502                 key = NULL;
 503
 504 lookup_again:
 505         /* search the current directory for the element name */
 506         _debug("lookup '%s'", name);
 507
 508         mutex_lock_nested(&dir->d_inode->i_mutex, I_MUTEX_PARENT);
 509
 510         start = jiffies;
 511         next = lookup_one_len(name, dir, nlen);
 512         cachefiles_hist(cachefiles_lookup_histogram, start);
 513         if (IS_ERR(next))
 514                 goto lookup_error;
 515
 516         _debug("next -> %p %s", next, next->d_inode ? "positive" : "negative");
 517
 518         if (!key)
 519                 object->new = !next->d_inode;
 520
 521         /* if this element of the path doesn't exist, then the lookup phase
 522          * failed, and we can release any readers in the certain knowledge that
 523          * there's nothing for them to actually read */
 524         if (!next->d_inode)
 525                 fscache_object_lookup_negative(&object->fscache);
 526
 527         /* we need to create the object if it's negative */
 528         if (key || object->type == FSCACHE_COOKIE_TYPE_INDEX) {
 529                 /* index objects and intervening tree levels must be subdirs */
 530                 if (!next->d_inode) {
 531                         ret = cachefiles_has_space(cache, 1, 0);
 532                         if (ret < 0)
 533                                 goto create_error;
 534
 535                         path.dentry = dir;
 536                         ret = security_path_mkdir(&path, next, 0);
 537                         if (ret < 0)
 538                                 goto create_error;
 539                         start = jiffies;
 540                         ret = vfs_mkdir(dir->d_inode, next, 0);
 541                         cachefiles_hist(cachefiles_mkdir_histogram, start);
 542                         if (ret < 0)
 543                                 goto create_error;
 544
 545                         ASSERT(next->d_inode);
 546
 547                         _debug("mkdir -> %p{%p{ino=%lu}}",
 548                                next, next->d_inode, next->d_inode->i_ino);
 549
 550                 } else if (!S_ISDIR(next->d_inode->i_mode)) {
 551                         kerror("inode %lu is not a directory",
 552                                next->d_inode->i_ino);
 553                         ret = -ENOBUFS;
 554                         goto error;
 555                 }
 556
 557         } else {
 558                 /* non-index objects start out life as files */
 559                 if (!next->d_inode) {
 560                         ret = cachefiles_has_space(cache, 1, 0);
 561                         if (ret < 0)
 562                                 goto create_error;
 563
 564                         path.dentry = dir;
 565                         ret = security_path_mknod(&path, next, S_IFREG, 0);
 566                         if (ret < 0)
 567                                 goto create_error;
 568                         start = jiffies;
 569                         ret = vfs_create(dir->d_inode, next, S_IFREG, true);
 570                         cachefiles_hist(cachefiles_create_histogram, start);
 571                         if (ret < 0)
 572                                 goto create_error;
 573
 574                         ASSERT(next->d_inode);
 575
 576                         _debug("create -> %p{%p{ino=%lu}}",
 577                                next, next->d_inode, next->d_inode->i_ino);
 578
 579                 } else if (!S_ISDIR(next->d_inode->i_mode) &&
 580                            !S_ISREG(next->d_inode->i_mode)
 581                            ) {
 582                         kerror("inode %lu is not a file or directory",
 583                                next->d_inode->i_ino);
 584                         ret = -ENOBUFS;
 585                         goto error;
 586                 }
 587         }
 588
 589         /* process the next component */
 590         if (key) {
 591                 _debug("advance");
 592                 mutex_unlock(&dir->d_inode->i_mutex);
 593                 dput(dir);
 594                 dir = next;
 595                 next = NULL;
 596                 goto advance;
 597         }
 598
 599         /* we've found the object we were looking for */
 600         object->dentry = next;
 601
 602         /* if we've found that the terminal object exists, then we need to
 603          * check its attributes and delete it if it's out of date */
 604         if (!object->new) {
 605                 _debug("validate '%*.*s'",
 606                        next->d_name.len, next->d_name.len, next->d_name.name);
 607
 608                 ret = cachefiles_check_object_xattr(object, auxdata);
 609                 if (ret == -ESTALE) {
 610                         /* delete the object (the deleter drops the directory
 611                          * mutex) */
 612                         object->dentry = NULL;
 613
 614                         ret = cachefiles_bury_object(cache, dir, next, true);
 615                         dput(next);
 616                         next = NULL;
 617
 618                         if (ret < 0)
 619                                 goto delete_error;
 620
 621                         _debug("redo lookup");
 622                         goto lookup_again;
 623                 }
 624         }
 625
 626         /* note that we're now using this object */
 627         ret = cachefiles_mark_object_active(cache, object);
 628
 629         mutex_unlock(&dir->d_inode->i_mutex);
 630         dput(dir);
 631         dir = NULL;
 632
 633         if (ret == -ETIMEDOUT)
 634                 goto mark_active_timed_out;
 635
 636         _debug("=== OBTAINED_OBJECT ===");
 637
 638         if (object->new) {
 639                 /* attach data to a newly constructed terminal object */
 640                 ret = cachefiles_set_object_xattr(object, auxdata);
 641                 if (ret < 0)
 642                         goto check_error;
 643         } else {
 644                 /* always update the atime on an object we've just looked up
 645                  * (this is used to keep track of culling, and atimes are only
 646                  * updated by read, write and readdir but not lookup or
 647                  * open) */
 648                 path.dentry = next;
 649                 touch_atime(&path);
 650         }
 651
 652         /* open a file interface onto a data file */
 653         if (object->type != FSCACHE_COOKIE_TYPE_INDEX) {
 654                 if (S_ISREG(object->dentry->d_inode->i_mode)) {
 655                         const struct address_space_operations *aops;
 656
 657                         ret = -EPERM;
 658                         aops = object->dentry->d_inode->i_mapping->a_ops;
 659                         if (!aops->bmap)
 660                                 goto check_error;
 661
 662                         object->backer = object->dentry;
 663                 } else {
 664                         BUG(); // TODO: open file in data-class subdir
 665                 }
 666         }
 667
 668         object->new = 0;
 669         fscache_obtained_object(&object->fscache);
 670
 671         _leave(" = 0 [%lu]", object->dentry->d_inode->i_ino);
 672         return 0;
 673
 674 create_error:
 675         _debug("create error %d", ret);
 676         if (ret == -EIO)
 677                 cachefiles_io_error(cache, "Create/mkdir failed");
 678         goto error;
 679
 680 mark_active_timed_out:
 681         _debug("mark active timed out");
 682         goto release_dentry;
 683
 684 check_error:
 685         _debug("check error %d", ret);
 686         write_lock(&cache->active_lock);
 687         rb_erase(&object->active_node, &cache->active_nodes);
 688         clear_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags);
 689         wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
 690         write_unlock(&cache->active_lock);
 691 release_dentry:
 692         dput(object->dentry);
 693         object->dentry = NULL;
 694         goto error_out;
 695
 696 delete_error:
 697         _debug("delete error %d", ret);
 698         goto error_out2;
 699
 700 lookup_error:
 701         _debug("lookup error %ld", PTR_ERR(next));
 702         ret = PTR_ERR(next);
 703         if (ret == -EIO)
 704                 cachefiles_io_error(cache, "Lookup failed");
 705         next = NULL;
 706 error:
 707         mutex_unlock(&dir->d_inode->i_mutex);
 708         dput(next);
 709 error_out2:
 710         dput(dir);
 711 error_out:
 712         _leave(" = error %d", -ret);
 713         return ret;
 714 }
 715
 716 /*
 717  * get a subdirectory
 718  */
 719 struct dentry *cachefiles_get_directory(struct cachefiles_cache *cache,
 720                                         struct dentry *dir,
 721                                         const char *dirname)
 722 {
 723         struct dentry *subdir;
 724         unsigned long start;
 725         struct path path;
 726         int ret;
 727
 728         _enter(",,%s", dirname);
 729
 730         /* search the current directory for the element name */
 731         mutex_lock(&dir->d_inode->i_mutex);
 732
 733         start = jiffies;
 734         subdir = lookup_one_len(dirname, dir, strlen(dirname));
 735         cachefiles_hist(cachefiles_lookup_histogram, start);
 736         if (IS_ERR(subdir)) {
 737                 if (PTR_ERR(subdir) == -ENOMEM)
 738                         goto nomem_d_alloc;
 739                 goto lookup_error;
 740         }
 741
 742         _debug("subdir -> %p %s",
 743                subdir, subdir->d_inode ? "positive" : "negative");
 744
 745         /* we need to create the subdir if it doesn't exist yet */
 746         if (!subdir->d_inode) {
 747                 ret = cachefiles_has_space(cache, 1, 0);
 748                 if (ret < 0)
 749                         goto mkdir_error;
 750
 751                 _debug("attempt mkdir");
 752
 753                 path.mnt = cache->mnt;
 754                 path.dentry = dir;
 755                 ret = security_path_mkdir(&path, subdir, 0700);
 756                 if (ret < 0)
 757                         goto mkdir_error;
 758                 ret = vfs_mkdir(dir->d_inode, subdir, 0700);
 759                 if (ret < 0)
 760                         goto mkdir_error;
 761
 762                 ASSERT(subdir->d_inode);
 763
 764                 _debug("mkdir -> %p{%p{ino=%lu}}",
 765                        subdir,
 766                        subdir->d_inode,
 767                        subdir->d_inode->i_ino);
 768         }
 769
 770         mutex_unlock(&dir->d_inode->i_mutex);
 771
 772         /* we need to make sure the subdir is a directory */
 773         ASSERT(subdir->d_inode);
 774
 775         if (!S_ISDIR(subdir->d_inode->i_mode)) {
 776                 kerror("%s is not a directory", dirname);
 777                 ret = -EIO;
 778                 goto check_error;
 779         }
 780
 781         ret = -EPERM;
 782         if (!subdir->d_inode->i_op ||
 783             !subdir->d_inode->i_op->setxattr ||
 784             !subdir->d_inode->i_op->getxattr ||
 785             !subdir->d_inode->i_op->lookup ||
 786             !subdir->d_inode->i_op->mkdir ||
 787             !subdir->d_inode->i_op->create ||
 788             !subdir->d_inode->i_op->rename ||
 789             !subdir->d_inode->i_op->rmdir ||
 790             !subdir->d_inode->i_op->unlink)
 791                 goto check_error;
 792
 793         _leave(" = [%lu]", subdir->d_inode->i_ino);
 794         return subdir;
 795
 796 check_error:
 797         dput(subdir);
 798         _leave(" = %d [check]", ret);
 799         return ERR_PTR(ret);
 800
 801 mkdir_error:
 802         mutex_unlock(&dir->d_inode->i_mutex);
 803         dput(subdir);
 804         kerror("mkdir %s failed with error %d", dirname, ret);
 805         return ERR_PTR(ret);
 806
 807 lookup_error:
 808         mutex_unlock(&dir->d_inode->i_mutex);
 809         ret = PTR_ERR(subdir);
 810         kerror("Lookup %s failed with error %d", dirname, ret);
 811         return ERR_PTR(ret);
 812
 813 nomem_d_alloc:
 814         mutex_unlock(&dir->d_inode->i_mutex);
 815         _leave(" = -ENOMEM");
 816         return ERR_PTR(-ENOMEM);
 817 }
 818
 819 /*
 820  * find out if an object is in use or not
 821  * - if finds object and it's not in use:
 822  *   - returns a pointer to the object and a reference on it
 823  *   - returns with the directory locked
 824  */
 825 static struct dentry *cachefiles_check_active(struct cachefiles_cache *cache,
 826                                               struct dentry *dir,
 827                                               char *filename)
 828 {
 829         struct cachefiles_object *object;
 830         struct rb_node *_n;
 831         struct dentry *victim;
 832         unsigned long start;
 833         int ret;
 834
 835         //_enter(",%*.*s/,%s",
 836         //       dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 837
 838         /* look up the victim */
 839         mutex_lock_nested(&dir->d_inode->i_mutex, 1);
 840
 841         start = jiffies;
 842         victim = lookup_one_len(filename, dir, strlen(filename));
 843         cachefiles_hist(cachefiles_lookup_histogram, start);
 844         if (IS_ERR(victim))
 845                 goto lookup_error;
 846
 847         //_debug("victim -> %p %s",
 848         //       victim, victim->d_inode ? "positive" : "negative");
 849
 850         /* if the object is no longer there then we probably retired the object
 851          * at the netfs's request whilst the cull was in progress
 852          */
 853         if (!victim->d_inode) {
 854                 mutex_unlock(&dir->d_inode->i_mutex);
 855                 dput(victim);
 856                 _leave(" = -ENOENT [absent]");
 857                 return ERR_PTR(-ENOENT);
 858         }
 859
 860         /* check to see if we're using this object */
 861         read_lock(&cache->active_lock);
 862
 863         _n = cache->active_nodes.rb_node;
 864
 865         while (_n) {
 866                 object = rb_entry(_n, struct cachefiles_object, active_node);
 867
 868                 if (object->dentry > victim)
 869                         _n = _n->rb_left;
 870                 else if (object->dentry < victim)
 871                         _n = _n->rb_right;
 872                 else
 873                         goto object_in_use;
 874         }
 875
 876         read_unlock(&cache->active_lock);
 877
 878         //_leave(" = %p", victim);
 879         return victim;
 880
 881 object_in_use:
 882         read_unlock(&cache->active_lock);
 883         mutex_unlock(&dir->d_inode->i_mutex);
 884         dput(victim);
 885         //_leave(" = -EBUSY [in use]");
 886         return ERR_PTR(-EBUSY);
 887
 888 lookup_error:
 889         mutex_unlock(&dir->d_inode->i_mutex);
 890         ret = PTR_ERR(victim);
 891         if (ret == -ENOENT) {
 892                 /* file or dir now absent - probably retired by netfs */
 893                 _leave(" = -ESTALE [absent]");
 894                 return ERR_PTR(-ESTALE);
 895         }
 896
 897         if (ret == -EIO) {
 898                 cachefiles_io_error(cache, "Lookup failed");
 899         } else if (ret != -ENOMEM) {
 900                 kerror("Internal error: %d", ret);
 901                 ret = -EIO;
 902         }
 903
 904         _leave(" = %d", ret);
 905         return ERR_PTR(ret);
 906 }
 907
 908 /*
 909  * cull an object if it's not in use
 910  * - called only by cache manager daemon
 911  */
 912 int cachefiles_cull(struct cachefiles_cache *cache, struct dentry *dir,
 913                     char *filename)
 914 {
 915         struct dentry *victim;
 916         int ret;
 917
 918         _enter(",%*.*s/,%s",
 919                dir->d_name.len, dir->d_name.len, dir->d_name.name, 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, victim->d_inode ? "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         if (ret < 0)
 942                 goto error;
 943
 944         dput(victim);
 945         _leave(" = 0");
 946         return 0;
 947
 948 error_unlock:
 949         mutex_unlock(&dir->d_inode->i_mutex);
 950 error:
 951         dput(victim);
 952         if (ret == -ENOENT) {
 953                 /* file or dir now absent - probably retired by netfs */
 954                 _leave(" = -ESTALE [absent]");
 955                 return -ESTALE;
 956         }
 957
 958         if (ret != -ENOMEM) {
 959                 kerror("Internal error: %d", ret);
 960                 ret = -EIO;
 961         }
 962
 963         _leave(" = %d", ret);
 964         return ret;
 965 }
 966
 967 /*
 968  * find out if an object is in use or not
 969  * - called only by cache manager daemon
 970  * - returns -EBUSY or 0 to indicate whether an object is in use or not
 971  */
 972 int cachefiles_check_in_use(struct cachefiles_cache *cache, struct dentry *dir,
 973                             char *filename)
 974 {
 975         struct dentry *victim;
 976
 977         //_enter(",%*.*s/,%s",
 978         //       dir->d_name.len, dir->d_name.len, dir->d_name.name, filename);
 979
 980         victim = cachefiles_check_active(cache, dir, filename);
 981         if (IS_ERR(victim))
 982                 return PTR_ERR(victim);
 983
 984         mutex_unlock(&dir->d_inode->i_mutex);
 985         dput(victim);
 986         //_leave(" = 0");
 987         return 0;
 988 }