fs/fscache/cookie.c

   1 /* netfs cookie management
   2  *
   3  * Copyright (C) 2004-2007 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 License
   8  * as published by the Free Software Foundation; either version
   9  * 2 of the License, or (at your option) any later version.
  10  *
  11  * See Documentation/filesystems/caching/netfs-api.txt for more information on
  12  * the netfs API.
  13  */
  14
  15 #define FSCACHE_DEBUG_LEVEL COOKIE
  16 #include <linux/module.h>
  17 #include <linux/slab.h>
  18 #include "internal.h"
  19
  20 struct kmem_cache *fscache_cookie_jar;
  21
  22 static atomic_t fscache_object_debug_id = ATOMIC_INIT(0);
  23
  24 #define fscache_cookie_hash_shift 15
  25 static struct hlist_bl_head fscache_cookie_hash[1 << fscache_cookie_hash_shift];
  26
  27 static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie,
  28                                             loff_t object_size);
  29 static int fscache_alloc_object(struct fscache_cache *cache,
  30                                 struct fscache_cookie *cookie);
  31 static int fscache_attach_object(struct fscache_cookie *cookie,
  32                                  struct fscache_object *object);
  33
  34 static void fscache_print_cookie(struct fscache_cookie *cookie, char prefix)
  35 {
  36         struct hlist_node *object;
  37         const u8 *k;
  38         unsigned loop;
  39
  40         pr_err("%c-cookie c=%p [p=%p fl=%lx nc=%u na=%u]\n",
  41                prefix, cookie, cookie->parent, cookie->flags,
  42                atomic_read(&cookie->n_children),
  43                atomic_read(&cookie->n_active));
  44         pr_err("%c-cookie d=%p n=%p\n",
  45                prefix, cookie->def, cookie->netfs_data);
  46
  47         object = READ_ONCE(cookie->backing_objects.first);
  48         if (object)
  49                 pr_err("%c-cookie o=%p\n",
  50                        prefix, hlist_entry(object, struct fscache_object, cookie_link));
  51
  52         pr_err("%c-key=[%u] '", prefix, cookie->key_len);
  53         k = (cookie->key_len <= sizeof(cookie->inline_key)) ?
  54                 cookie->inline_key : cookie->key;
  55         for (loop = 0; loop < cookie->key_len; loop++)
  56                 pr_cont("%02x", k[loop]);
  57         pr_cont("'\n");
  58 }
  59
  60 void fscache_free_cookie(struct fscache_cookie *cookie)
  61 {
  62         if (cookie) {
  63                 BUG_ON(!hlist_empty(&cookie->backing_objects));
  64                 if (cookie->aux_len > sizeof(cookie->inline_aux))
  65                         kfree(cookie->aux);
  66                 if (cookie->key_len > sizeof(cookie->inline_key))
  67                         kfree(cookie->key);
  68                 kmem_cache_free(fscache_cookie_jar, cookie);
  69         }
  70 }
  71
  72 /*
  73  * Set the index key in a cookie.  The cookie struct has space for a 16-byte
  74  * key plus length and hash, but if that's not big enough, it's instead a
  75  * pointer to a buffer containing 3 bytes of hash, 1 byte of length and then
  76  * the key data.
  77  */
  78 static int fscache_set_key(struct fscache_cookie *cookie,
  79                            const void *index_key, size_t index_key_len)
  80 {
  81         unsigned long long h;
  82         u32 *buf;
  83         int bufs;
  84         int i;
  85
  86         bufs = DIV_ROUND_UP(index_key_len, sizeof(*buf));
  87
  88         if (index_key_len > sizeof(cookie->inline_key)) {
  89                 buf = kcalloc(bufs, sizeof(*buf), GFP_KERNEL);
  90                 if (!buf)
  91                         return -ENOMEM;
  92                 cookie->key = buf;
  93         } else {
  94                 buf = (u32 *)cookie->inline_key;
  95         }
  96
  97         memcpy(buf, index_key, index_key_len);
  98
  99         /* Calculate a hash and combine this with the length in the first word
 100          * or first half word
 101          */
 102         h = (unsigned long)cookie->parent;
 103         h += index_key_len + cookie->type;
 104
 105         for (i = 0; i < bufs; i++)
 106                 h += buf[i];
 107
 108         cookie->key_hash = h ^ (h >> 32);
 109         return 0;
 110 }
 111
 112 static long fscache_compare_cookie(const struct fscache_cookie *a,
 113                                    const struct fscache_cookie *b)
 114 {
 115         const void *ka, *kb;
 116
 117         if (a->key_hash != b->key_hash)
 118                 return (long)a->key_hash - (long)b->key_hash;
 119         if (a->parent != b->parent)
 120                 return (long)a->parent - (long)b->parent;
 121         if (a->key_len != b->key_len)
 122                 return (long)a->key_len - (long)b->key_len;
 123         if (a->type != b->type)
 124                 return (long)a->type - (long)b->type;
 125
 126         if (a->key_len <= sizeof(a->inline_key)) {
 127                 ka = &a->inline_key;
 128                 kb = &b->inline_key;
 129         } else {
 130                 ka = a->key;
 131                 kb = b->key;
 132         }
 133         return memcmp(ka, kb, a->key_len);
 134 }
 135
 136 /*
 137  * Allocate a cookie.
 138  */
 139 struct fscache_cookie *fscache_alloc_cookie(
 140         struct fscache_cookie *parent,
 141         const struct fscache_cookie_def *def,
 142         const void *index_key, size_t index_key_len,
 143         const void *aux_data, size_t aux_data_len,
 144         void *netfs_data,
 145         loff_t object_size)
 146 {
 147         struct fscache_cookie *cookie;
 148
 149         /* allocate and initialise a cookie */
 150         cookie = kmem_cache_zalloc(fscache_cookie_jar, GFP_KERNEL);
 151         if (!cookie)
 152                 return NULL;
 153
 154         cookie->key_len = index_key_len;
 155         cookie->aux_len = aux_data_len;
 156
 157         if (fscache_set_key(cookie, index_key, index_key_len) < 0)
 158                 goto nomem;
 159
 160         if (cookie->aux_len <= sizeof(cookie->inline_aux)) {
 161                 memcpy(cookie->inline_aux, aux_data, cookie->aux_len);
 162         } else {
 163                 cookie->aux = kmemdup(aux_data, cookie->aux_len, GFP_KERNEL);
 164                 if (!cookie->aux)
 165                         goto nomem;
 166         }
 167
 168         atomic_set(&cookie->usage, 1);
 169         atomic_set(&cookie->n_children, 0);
 170
 171         /* We keep the active count elevated until relinquishment to prevent an
 172          * attempt to wake up every time the object operations queue quiesces.
 173          */
 174         atomic_set(&cookie->n_active, 1);
 175
 176         cookie->def             = def;
 177         cookie->parent          = parent;
 178         cookie->netfs_data      = netfs_data;
 179         cookie->flags           = (1 << FSCACHE_COOKIE_NO_DATA_YET);
 180         cookie->type            = def->type;
 181         spin_lock_init(&cookie->lock);
 182         spin_lock_init(&cookie->stores_lock);
 183         INIT_HLIST_HEAD(&cookie->backing_objects);
 184
 185         /* radix tree insertion won't use the preallocation pool unless it's
 186          * told it may not wait */
 187         INIT_RADIX_TREE(&cookie->stores, GFP_NOFS & ~__GFP_DIRECT_RECLAIM);
 188         return cookie;
 189
 190 nomem:
 191         fscache_free_cookie(cookie);
 192         return NULL;
 193 }
 194
 195 /*
 196  * Attempt to insert the new cookie into the hash.  If there's a collision, we
 197  * return the old cookie if it's not in use and an error otherwise.
 198  */
 199 struct fscache_cookie *fscache_hash_cookie(struct fscache_cookie *candidate)
 200 {
 201         struct fscache_cookie *cursor;
 202         struct hlist_bl_head *h;
 203         struct hlist_bl_node *p;
 204         unsigned int bucket;
 205
 206         bucket = candidate->key_hash & (ARRAY_SIZE(fscache_cookie_hash) - 1);
 207         h = &fscache_cookie_hash[bucket];
 208
 209         hlist_bl_lock(h);
 210         hlist_bl_for_each_entry(cursor, p, h, hash_link) {
 211                 if (fscache_compare_cookie(candidate, cursor) == 0)
 212                         goto collision;
 213         }
 214
 215         __set_bit(FSCACHE_COOKIE_ACQUIRED, &candidate->flags);
 216         fscache_cookie_get(candidate->parent, fscache_cookie_get_acquire_parent);
 217         atomic_inc(&candidate->parent->n_children);
 218         hlist_bl_add_head(&candidate->hash_link, h);
 219         hlist_bl_unlock(h);
 220         return candidate;
 221
 222 collision:
 223         if (test_and_set_bit(FSCACHE_COOKIE_ACQUIRED, &cursor->flags)) {
 224                 trace_fscache_cookie(cursor, fscache_cookie_collision,
 225                                      atomic_read(&cursor->usage));
 226                 pr_err("Duplicate cookie detected\n");
 227                 fscache_print_cookie(cursor, 'O');
 228                 fscache_print_cookie(candidate, 'N');
 229                 hlist_bl_unlock(h);
 230                 return NULL;
 231         }
 232
 233         fscache_cookie_get(cursor, fscache_cookie_get_reacquire);
 234         hlist_bl_unlock(h);
 235         return cursor;
 236 }
 237
 238 /*
 239  * request a cookie to represent an object (index, datafile, xattr, etc)
 240  * - parent specifies the parent object
 241  *   - the top level index cookie for each netfs is stored in the fscache_netfs
 242  *     struct upon registration
 243  * - def points to the definition
 244  * - the netfs_data will be passed to the functions pointed to in *def
 245  * - all attached caches will be searched to see if they contain this object
 246  * - index objects aren't stored on disk until there's a dependent file that
 247  *   needs storing
 248  * - other objects are stored in a selected cache immediately, and all the
 249  *   indices forming the path to it are instantiated if necessary
 250  * - we never let on to the netfs about errors
 251  *   - we may set a negative cookie pointer, but that's okay
 252  */
 253 struct fscache_cookie *__fscache_acquire_cookie(
 254         struct fscache_cookie *parent,
 255         const struct fscache_cookie_def *def,
 256         const void *index_key, size_t index_key_len,
 257         const void *aux_data, size_t aux_data_len,
 258         void *netfs_data,
 259         loff_t object_size,
 260         bool enable)
 261 {
 262         struct fscache_cookie *candidate, *cookie;
 263
 264         BUG_ON(!def);
 265
 266         _enter("{%s},{%s},%p,%u",
 267                parent ? (char *) parent->def->name : "<no-parent>",
 268                def->name, netfs_data, enable);
 269
 270         if (!index_key || !index_key_len || index_key_len > 255 || aux_data_len > 255)
 271                 return NULL;
 272         if (!aux_data || !aux_data_len) {
 273                 aux_data = NULL;
 274                 aux_data_len = 0;
 275         }
 276
 277         fscache_stat(&fscache_n_acquires);
 278
 279         /* if there's no parent cookie, then we don't create one here either */
 280         if (!parent) {
 281                 fscache_stat(&fscache_n_acquires_null);
 282                 _leave(" [no parent]");
 283                 return NULL;
 284         }
 285
 286         /* validate the definition */
 287         BUG_ON(!def->name[0]);
 288
 289         BUG_ON(def->type == FSCACHE_COOKIE_TYPE_INDEX &&
 290                parent->type != FSCACHE_COOKIE_TYPE_INDEX);
 291
 292         candidate = fscache_alloc_cookie(parent, def,
 293                                          index_key, index_key_len,
 294                                          aux_data, aux_data_len,
 295                                          netfs_data, object_size);
 296         if (!candidate) {
 297                 fscache_stat(&fscache_n_acquires_oom);
 298                 _leave(" [ENOMEM]");
 299                 return NULL;
 300         }
 301
 302         cookie = fscache_hash_cookie(candidate);
 303         if (!cookie) {
 304                 trace_fscache_cookie(candidate, fscache_cookie_discard, 1);
 305                 goto out;
 306         }
 307
 308         if (cookie == candidate)
 309                 candidate = NULL;
 310
 311         switch (cookie->type) {
 312         case FSCACHE_COOKIE_TYPE_INDEX:
 313                 fscache_stat(&fscache_n_cookie_index);
 314                 break;
 315         case FSCACHE_COOKIE_TYPE_DATAFILE:
 316                 fscache_stat(&fscache_n_cookie_data);
 317                 break;
 318         default:
 319                 fscache_stat(&fscache_n_cookie_special);
 320                 break;
 321         }
 322
 323         trace_fscache_acquire(cookie);
 324
 325         if (enable) {
 326                 /* if the object is an index then we need do nothing more here
 327                  * - we create indices on disk when we need them as an index
 328                  * may exist in multiple caches */
 329                 if (cookie->type != FSCACHE_COOKIE_TYPE_INDEX) {
 330                         if (fscache_acquire_non_index_cookie(cookie, object_size) == 0) {
 331                                 set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
 332                         } else {
 333                                 atomic_dec(&parent->n_children);
 334                                 fscache_cookie_put(cookie,
 335                                                    fscache_cookie_put_acquire_nobufs);
 336                                 fscache_stat(&fscache_n_acquires_nobufs);
 337                                 _leave(" = NULL");
 338                                 return NULL;
 339                         }
 340                 } else {
 341                         set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
 342                 }
 343         }
 344
 345         fscache_stat(&fscache_n_acquires_ok);
 346
 347 out:
 348         fscache_free_cookie(candidate);
 349         return cookie;
 350 }
 351 EXPORT_SYMBOL(__fscache_acquire_cookie);
 352
 353 /*
 354  * Enable a cookie to permit it to accept new operations.
 355  */
 356 void __fscache_enable_cookie(struct fscache_cookie *cookie,
 357                              const void *aux_data,
 358                              loff_t object_size,
 359                              bool (*can_enable)(void *data),
 360                              void *data)
 361 {
 362         _enter("%p", cookie);
 363
 364         trace_fscache_enable(cookie);
 365
 366         wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK,
 367                          TASK_UNINTERRUPTIBLE);
 368
 369         fscache_update_aux(cookie, aux_data);
 370
 371         if (test_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags))
 372                 goto out_unlock;
 373
 374         if (can_enable && !can_enable(data)) {
 375                 /* The netfs decided it didn't want to enable after all */
 376         } else if (cookie->type != FSCACHE_COOKIE_TYPE_INDEX) {
 377                 /* Wait for outstanding disablement to complete */
 378                 __fscache_wait_on_invalidate(cookie);
 379
 380                 if (fscache_acquire_non_index_cookie(cookie, object_size) == 0)
 381                         set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
 382         } else {
 383                 set_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags);
 384         }
 385
 386 out_unlock:
 387         clear_bit_unlock(FSCACHE_COOKIE_ENABLEMENT_LOCK, &cookie->flags);
 388         wake_up_bit(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK);
 389 }
 390 EXPORT_SYMBOL(__fscache_enable_cookie);
 391
 392 /*
 393  * acquire a non-index cookie
 394  * - this must make sure the index chain is instantiated and instantiate the
 395  *   object representation too
 396  */
 397 static int fscache_acquire_non_index_cookie(struct fscache_cookie *cookie,
 398                                             loff_t object_size)
 399 {
 400         struct fscache_object *object;
 401         struct fscache_cache *cache;
 402         int ret;
 403
 404         _enter("");
 405
 406         set_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags);
 407
 408         /* now we need to see whether the backing objects for this cookie yet
 409          * exist, if not there'll be nothing to search */
 410         down_read(&fscache_addremove_sem);
 411
 412         if (list_empty(&fscache_cache_list)) {
 413                 up_read(&fscache_addremove_sem);
 414                 _leave(" = 0 [no caches]");
 415                 return 0;
 416         }
 417
 418         /* select a cache in which to store the object */
 419         cache = fscache_select_cache_for_object(cookie->parent);
 420         if (!cache) {
 421                 up_read(&fscache_addremove_sem);
 422                 fscache_stat(&fscache_n_acquires_no_cache);
 423                 _leave(" = -ENOMEDIUM [no cache]");
 424                 return -ENOMEDIUM;
 425         }
 426
 427         _debug("cache %s", cache->tag->name);
 428
 429         set_bit(FSCACHE_COOKIE_LOOKING_UP, &cookie->flags);
 430
 431         /* ask the cache to allocate objects for this cookie and its parent
 432          * chain */
 433         ret = fscache_alloc_object(cache, cookie);
 434         if (ret < 0) {
 435                 up_read(&fscache_addremove_sem);
 436                 _leave(" = %d", ret);
 437                 return ret;
 438         }
 439
 440         spin_lock(&cookie->lock);
 441         if (hlist_empty(&cookie->backing_objects)) {
 442                 spin_unlock(&cookie->lock);
 443                 goto unavailable;
 444         }
 445
 446         object = hlist_entry(cookie->backing_objects.first,
 447                              struct fscache_object, cookie_link);
 448
 449         fscache_set_store_limit(object, object_size);
 450
 451         /* initiate the process of looking up all the objects in the chain
 452          * (done by fscache_initialise_object()) */
 453         fscache_raise_event(object, FSCACHE_OBJECT_EV_NEW_CHILD);
 454
 455         spin_unlock(&cookie->lock);
 456
 457         /* we may be required to wait for lookup to complete at this point */
 458         if (!fscache_defer_lookup) {
 459                 _debug("non-deferred lookup %p", &cookie->flags);
 460                 wait_on_bit(&cookie->flags, FSCACHE_COOKIE_LOOKING_UP,
 461                             TASK_UNINTERRUPTIBLE);
 462                 _debug("complete");
 463                 if (test_bit(FSCACHE_COOKIE_UNAVAILABLE, &cookie->flags))
 464                         goto unavailable;
 465         }
 466
 467         up_read(&fscache_addremove_sem);
 468         _leave(" = 0 [deferred]");
 469         return 0;
 470
 471 unavailable:
 472         up_read(&fscache_addremove_sem);
 473         _leave(" = -ENOBUFS");
 474         return -ENOBUFS;
 475 }
 476
 477 /*
 478  * recursively allocate cache object records for a cookie/cache combination
 479  * - caller must be holding the addremove sem
 480  */
 481 static int fscache_alloc_object(struct fscache_cache *cache,
 482                                 struct fscache_cookie *cookie)
 483 {
 484         struct fscache_object *object;
 485         int ret;
 486
 487         _enter("%p,%p{%s}", cache, cookie, cookie->def->name);
 488
 489         spin_lock(&cookie->lock);
 490         hlist_for_each_entry(object, &cookie->backing_objects,
 491                              cookie_link) {
 492                 if (object->cache == cache)
 493                         goto object_already_extant;
 494         }
 495         spin_unlock(&cookie->lock);
 496
 497         /* ask the cache to allocate an object (we may end up with duplicate
 498          * objects at this stage, but we sort that out later) */
 499         fscache_stat(&fscache_n_cop_alloc_object);
 500         object = cache->ops->alloc_object(cache, cookie);
 501         fscache_stat_d(&fscache_n_cop_alloc_object);
 502         if (IS_ERR(object)) {
 503                 fscache_stat(&fscache_n_object_no_alloc);
 504                 ret = PTR_ERR(object);
 505                 goto error;
 506         }
 507
 508         ASSERTCMP(object->cookie, ==, cookie);
 509         fscache_stat(&fscache_n_object_alloc);
 510
 511         object->debug_id = atomic_inc_return(&fscache_object_debug_id);
 512
 513         _debug("ALLOC OBJ%x: %s {%lx}",
 514                object->debug_id, cookie->def->name, object->events);
 515
 516         ret = fscache_alloc_object(cache, cookie->parent);
 517         if (ret < 0)
 518                 goto error_put;
 519
 520         /* only attach if we managed to allocate all we needed, otherwise
 521          * discard the object we just allocated and instead use the one
 522          * attached to the cookie */
 523         if (fscache_attach_object(cookie, object) < 0) {
 524                 fscache_stat(&fscache_n_cop_put_object);
 525                 cache->ops->put_object(object, fscache_obj_put_attach_fail);
 526                 fscache_stat_d(&fscache_n_cop_put_object);
 527         }
 528
 529         _leave(" = 0");
 530         return 0;
 531
 532 object_already_extant:
 533         ret = -ENOBUFS;
 534         if (fscache_object_is_dying(object) ||
 535             fscache_cache_is_broken(object)) {
 536                 spin_unlock(&cookie->lock);
 537                 goto error;
 538         }
 539         spin_unlock(&cookie->lock);
 540         _leave(" = 0 [found]");
 541         return 0;
 542
 543 error_put:
 544         fscache_stat(&fscache_n_cop_put_object);
 545         cache->ops->put_object(object, fscache_obj_put_alloc_fail);
 546         fscache_stat_d(&fscache_n_cop_put_object);
 547 error:
 548         _leave(" = %d", ret);
 549         return ret;
 550 }
 551
 552 /*
 553  * attach a cache object to a cookie
 554  */
 555 static int fscache_attach_object(struct fscache_cookie *cookie,
 556                                  struct fscache_object *object)
 557 {
 558         struct fscache_object *p;
 559         struct fscache_cache *cache = object->cache;
 560         int ret;
 561
 562         _enter("{%s},{OBJ%x}", cookie->def->name, object->debug_id);
 563
 564         ASSERTCMP(object->cookie, ==, cookie);
 565
 566         spin_lock(&cookie->lock);
 567
 568         /* there may be multiple initial creations of this object, but we only
 569          * want one */
 570         ret = -EEXIST;
 571         hlist_for_each_entry(p, &cookie->backing_objects, cookie_link) {
 572                 if (p->cache == object->cache) {
 573                         if (fscache_object_is_dying(p))
 574                                 ret = -ENOBUFS;
 575                         goto cant_attach_object;
 576                 }
 577         }
 578
 579         /* pin the parent object */
 580         spin_lock_nested(&cookie->parent->lock, 1);
 581         hlist_for_each_entry(p, &cookie->parent->backing_objects,
 582                              cookie_link) {
 583                 if (p->cache == object->cache) {
 584                         if (fscache_object_is_dying(p)) {
 585                                 ret = -ENOBUFS;
 586                                 spin_unlock(&cookie->parent->lock);
 587                                 goto cant_attach_object;
 588                         }
 589                         object->parent = p;
 590                         spin_lock(&p->lock);
 591                         p->n_children++;
 592                         spin_unlock(&p->lock);
 593                         break;
 594                 }
 595         }
 596         spin_unlock(&cookie->parent->lock);
 597
 598         /* attach to the cache's object list */
 599         if (list_empty(&object->cache_link)) {
 600                 spin_lock(&cache->object_list_lock);
 601                 list_add(&object->cache_link, &cache->object_list);
 602                 spin_unlock(&cache->object_list_lock);
 603         }
 604
 605         /* Attach to the cookie.  The object already has a ref on it. */
 606         hlist_add_head(&object->cookie_link, &cookie->backing_objects);
 607
 608         fscache_objlist_add(object);
 609         ret = 0;
 610
 611 cant_attach_object:
 612         spin_unlock(&cookie->lock);
 613         _leave(" = %d", ret);
 614         return ret;
 615 }
 616
 617 /*
 618  * Invalidate an object.  Callable with spinlocks held.
 619  */
 620 void __fscache_invalidate(struct fscache_cookie *cookie)
 621 {
 622         struct fscache_object *object;
 623
 624         _enter("{%s}", cookie->def->name);
 625
 626         fscache_stat(&fscache_n_invalidates);
 627
 628         /* Only permit invalidation of data files.  Invalidating an index will
 629          * require the caller to release all its attachments to the tree rooted
 630          * there, and if it's doing that, it may as well just retire the
 631          * cookie.
 632          */
 633         ASSERTCMP(cookie->type, ==, FSCACHE_COOKIE_TYPE_DATAFILE);
 634
 635         /* If there's an object, we tell the object state machine to handle the
 636          * invalidation on our behalf, otherwise there's nothing to do.
 637          */
 638         if (!hlist_empty(&cookie->backing_objects)) {
 639                 spin_lock(&cookie->lock);
 640
 641                 if (fscache_cookie_enabled(cookie) &&
 642                     !hlist_empty(&cookie->backing_objects) &&
 643                     !test_and_set_bit(FSCACHE_COOKIE_INVALIDATING,
 644                                       &cookie->flags)) {
 645                         object = hlist_entry(cookie->backing_objects.first,
 646                                              struct fscache_object,
 647                                              cookie_link);
 648                         if (fscache_object_is_live(object))
 649                                 fscache_raise_event(
 650                                         object, FSCACHE_OBJECT_EV_INVALIDATE);
 651                 }
 652
 653                 spin_unlock(&cookie->lock);
 654         }
 655
 656         _leave("");
 657 }
 658 EXPORT_SYMBOL(__fscache_invalidate);
 659
 660 /*
 661  * Wait for object invalidation to complete.
 662  */
 663 void __fscache_wait_on_invalidate(struct fscache_cookie *cookie)
 664 {
 665         _enter("%p", cookie);
 666
 667         wait_on_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING,
 668                     TASK_UNINTERRUPTIBLE);
 669
 670         _leave("");
 671 }
 672 EXPORT_SYMBOL(__fscache_wait_on_invalidate);
 673
 674 /*
 675  * update the index entries backing a cookie
 676  */
 677 void __fscache_update_cookie(struct fscache_cookie *cookie, const void *aux_data)
 678 {
 679         struct fscache_object *object;
 680
 681         fscache_stat(&fscache_n_updates);
 682
 683         if (!cookie) {
 684                 fscache_stat(&fscache_n_updates_null);
 685                 _leave(" [no cookie]");
 686                 return;
 687         }
 688
 689         _enter("{%s}", cookie->def->name);
 690
 691         spin_lock(&cookie->lock);
 692
 693         fscache_update_aux(cookie, aux_data);
 694
 695         if (fscache_cookie_enabled(cookie)) {
 696                 /* update the index entry on disk in each cache backing this
 697                  * cookie.
 698                  */
 699                 hlist_for_each_entry(object,
 700                                      &cookie->backing_objects, cookie_link) {
 701                         fscache_raise_event(object, FSCACHE_OBJECT_EV_UPDATE);
 702                 }
 703         }
 704
 705         spin_unlock(&cookie->lock);
 706         _leave("");
 707 }
 708 EXPORT_SYMBOL(__fscache_update_cookie);
 709
 710 /*
 711  * Disable a cookie to stop it from accepting new requests from the netfs.
 712  */
 713 void __fscache_disable_cookie(struct fscache_cookie *cookie,
 714                               const void *aux_data,
 715                               bool invalidate)
 716 {
 717         struct fscache_object *object;
 718         bool awaken = false;
 719
 720         _enter("%p,%u", cookie, invalidate);
 721
 722         trace_fscache_disable(cookie);
 723
 724         ASSERTCMP(atomic_read(&cookie->n_active), >, 0);
 725
 726         if (atomic_read(&cookie->n_children) != 0) {
 727                 pr_err("Cookie '%s' still has children\n",
 728                        cookie->def->name);
 729                 BUG();
 730         }
 731
 732         wait_on_bit_lock(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK,
 733                          TASK_UNINTERRUPTIBLE);
 734
 735         fscache_update_aux(cookie, aux_data);
 736
 737         if (!test_and_clear_bit(FSCACHE_COOKIE_ENABLED, &cookie->flags))
 738                 goto out_unlock_enable;
 739
 740         /* If the cookie is being invalidated, wait for that to complete first
 741          * so that we can reuse the flag.
 742          */
 743         __fscache_wait_on_invalidate(cookie);
 744
 745         /* Dispose of the backing objects */
 746         set_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags);
 747
 748         spin_lock(&cookie->lock);
 749         if (!hlist_empty(&cookie->backing_objects)) {
 750                 hlist_for_each_entry(object, &cookie->backing_objects, cookie_link) {
 751                         if (invalidate)
 752                                 set_bit(FSCACHE_OBJECT_RETIRED, &object->flags);
 753                         clear_bit(FSCACHE_OBJECT_PENDING_WRITE, &object->flags);
 754                         fscache_raise_event(object, FSCACHE_OBJECT_EV_KILL);
 755                 }
 756         } else {
 757                 if (test_and_clear_bit(FSCACHE_COOKIE_INVALIDATING, &cookie->flags))
 758                         awaken = true;
 759         }
 760         spin_unlock(&cookie->lock);
 761         if (awaken)
 762                 wake_up_bit(&cookie->flags, FSCACHE_COOKIE_INVALIDATING);
 763
 764         /* Wait for cessation of activity requiring access to the netfs (when
 765          * n_active reaches 0).  This makes sure outstanding reads and writes
 766          * have completed.
 767          */
 768         if (!atomic_dec_and_test(&cookie->n_active)) {
 769                 wait_var_event(&cookie->n_active,
 770                                !atomic_read(&cookie->n_active));
 771         }
 772
 773         /* Make sure any pending writes are cancelled. */
 774         if (cookie->type != FSCACHE_COOKIE_TYPE_INDEX)
 775                 fscache_invalidate_writes(cookie);
 776
 777         /* Reset the cookie state if it wasn't relinquished */
 778         if (!test_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags)) {
 779                 atomic_inc(&cookie->n_active);
 780                 set_bit(FSCACHE_COOKIE_NO_DATA_YET, &cookie->flags);
 781         }
 782
 783 out_unlock_enable:
 784         clear_bit_unlock(FSCACHE_COOKIE_ENABLEMENT_LOCK, &cookie->flags);
 785         wake_up_bit(&cookie->flags, FSCACHE_COOKIE_ENABLEMENT_LOCK);
 786         _leave("");
 787 }
 788 EXPORT_SYMBOL(__fscache_disable_cookie);
 789
 790 /*
 791  * release a cookie back to the cache
 792  * - the object will be marked as recyclable on disk if retire is true
 793  * - all dependents of this cookie must have already been unregistered
 794  *   (indices/files/pages)
 795  */
 796 void __fscache_relinquish_cookie(struct fscache_cookie *cookie,
 797                                  const void *aux_data,
 798                                  bool retire)
 799 {
 800         fscache_stat(&fscache_n_relinquishes);
 801         if (retire)
 802                 fscache_stat(&fscache_n_relinquishes_retire);
 803
 804         if (!cookie) {
 805                 fscache_stat(&fscache_n_relinquishes_null);
 806                 _leave(" [no cookie]");
 807                 return;
 808         }
 809
 810         _enter("%p{%s,%p,%d},%d",
 811                cookie, cookie->def->name, cookie->netfs_data,
 812                atomic_read(&cookie->n_active), retire);
 813
 814         trace_fscache_relinquish(cookie, retire);
 815
 816         /* No further netfs-accessing operations on this cookie permitted */
 817         if (test_and_set_bit(FSCACHE_COOKIE_RELINQUISHED, &cookie->flags))
 818                 BUG();
 819
 820         __fscache_disable_cookie(cookie, aux_data, retire);
 821
 822         /* Clear pointers back to the netfs */
 823         cookie->netfs_data      = NULL;
 824         cookie->def             = NULL;
 825         BUG_ON(!radix_tree_empty(&cookie->stores));
 826
 827         if (cookie->parent) {
 828                 ASSERTCMP(atomic_read(&cookie->parent->usage), >, 0);
 829                 ASSERTCMP(atomic_read(&cookie->parent->n_children), >, 0);
 830                 atomic_dec(&cookie->parent->n_children);
 831         }
 832
 833         /* Dispose of the netfs's link to the cookie */
 834         ASSERTCMP(atomic_read(&cookie->usage), >, 0);
 835         fscache_cookie_put(cookie, fscache_cookie_put_relinquish);
 836
 837         _leave("");
 838 }
 839 EXPORT_SYMBOL(__fscache_relinquish_cookie);
 840
 841 /*
 842  * Remove a cookie from the hash table.
 843  */
 844 static void fscache_unhash_cookie(struct fscache_cookie *cookie)
 845 {
 846         struct hlist_bl_head *h;
 847         unsigned int bucket;
 848
 849         bucket = cookie->key_hash & (ARRAY_SIZE(fscache_cookie_hash) - 1);
 850         h = &fscache_cookie_hash[bucket];
 851
 852         hlist_bl_lock(h);
 853         hlist_bl_del(&cookie->hash_link);
 854         hlist_bl_unlock(h);
 855 }
 856
 857 /*
 858  * Drop a reference to a cookie.
 859  */
 860 void fscache_cookie_put(struct fscache_cookie *cookie,
 861                         enum fscache_cookie_trace where)
 862 {
 863         struct fscache_cookie *parent;
 864         int usage;
 865
 866         _enter("%p", cookie);
 867
 868         do {
 869                 usage = atomic_dec_return(&cookie->usage);
 870                 trace_fscache_cookie(cookie, where, usage);
 871
 872                 if (usage > 0)
 873                         return;
 874                 BUG_ON(usage < 0);
 875
 876                 parent = cookie->parent;
 877                 fscache_unhash_cookie(cookie);
 878                 fscache_free_cookie(cookie);
 879
 880                 cookie = parent;
 881                 where = fscache_cookie_put_parent;
 882         } while (cookie);
 883
 884         _leave("");
 885 }
 886
 887 /*
 888  * check the consistency between the netfs inode and the backing cache
 889  *
 890  * NOTE: it only serves no-index type
 891  */
 892 int __fscache_check_consistency(struct fscache_cookie *cookie,
 893                                 const void *aux_data)
 894 {
 895         struct fscache_operation *op;
 896         struct fscache_object *object;
 897         bool wake_cookie = false;
 898         int ret;
 899
 900         _enter("%p,", cookie);
 901
 902         ASSERTCMP(cookie->type, ==, FSCACHE_COOKIE_TYPE_DATAFILE);
 903
 904         if (fscache_wait_for_deferred_lookup(cookie) < 0)
 905                 return -ERESTARTSYS;
 906
 907         if (hlist_empty(&cookie->backing_objects))
 908                 return 0;
 909
 910         op = kzalloc(sizeof(*op), GFP_NOIO | __GFP_NOMEMALLOC | __GFP_NORETRY);
 911         if (!op)
 912                 return -ENOMEM;
 913
 914         fscache_operation_init(cookie, op, NULL, NULL, NULL);
 915         op->flags = FSCACHE_OP_MYTHREAD |
 916                 (1 << FSCACHE_OP_WAITING) |
 917                 (1 << FSCACHE_OP_UNUSE_COOKIE);
 918         trace_fscache_page_op(cookie, NULL, op, fscache_page_op_check_consistency);
 919
 920         spin_lock(&cookie->lock);
 921
 922         fscache_update_aux(cookie, aux_data);
 923
 924         if (!fscache_cookie_enabled(cookie) ||
 925             hlist_empty(&cookie->backing_objects))
 926                 goto inconsistent;
 927         object = hlist_entry(cookie->backing_objects.first,
 928                              struct fscache_object, cookie_link);
 929         if (test_bit(FSCACHE_IOERROR, &object->cache->flags))
 930                 goto inconsistent;
 931
 932         op->debug_id = atomic_inc_return(&fscache_op_debug_id);
 933
 934         __fscache_use_cookie(cookie);
 935         if (fscache_submit_op(object, op) < 0)
 936                 goto submit_failed;
 937
 938         /* the work queue now carries its own ref on the object */
 939         spin_unlock(&cookie->lock);
 940
 941         ret = fscache_wait_for_operation_activation(object, op, NULL, NULL);
 942         if (ret == 0) {
 943                 /* ask the cache to honour the operation */
 944                 ret = object->cache->ops->check_consistency(op);
 945                 fscache_op_complete(op, false);
 946         } else if (ret == -ENOBUFS) {
 947                 ret = 0;
 948         }
 949
 950         fscache_put_operation(op);
 951         _leave(" = %d", ret);
 952         return ret;
 953
 954 submit_failed:
 955         wake_cookie = __fscache_unuse_cookie(cookie);
 956 inconsistent:
 957         spin_unlock(&cookie->lock);
 958         if (wake_cookie)
 959                 __fscache_wake_unused_cookie(cookie);
 960         kfree(op);
 961         _leave(" = -ESTALE");
 962         return -ESTALE;
 963 }
 964 EXPORT_SYMBOL(__fscache_check_consistency);