1 /* FS-Cache interface to CacheFiles 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/slab.h> 13 #include <linux/mount.h> 14 #include "internal.h" 15 16 struct cachefiles_lookup_data { 17 struct cachefiles_xattr *auxdata; /* auxiliary data */ 18 char *key; /* key path */ 19 }; 20 21 static int cachefiles_attr_changed(struct fscache_object *_object); 22 23 /* 24 * allocate an object record for a cookie lookup and prepare the lookup data 25 */ 26 static struct fscache_object *cachefiles_alloc_object( 27 struct fscache_cache *_cache, 28 struct fscache_cookie *cookie) 29 { 30 struct cachefiles_lookup_data *lookup_data; 31 struct cachefiles_object *object; 32 struct cachefiles_cache *cache; 33 struct cachefiles_xattr *auxdata; 34 unsigned keylen, auxlen; 35 void *buffer; 36 char *key; 37 38 cache = container_of(_cache, struct cachefiles_cache, cache); 39 40 _enter("{%s},%p,", cache->cache.identifier, cookie); 41 42 lookup_data = kmalloc(sizeof(*lookup_data), cachefiles_gfp); 43 if (!lookup_data) 44 goto nomem_lookup_data; 45 46 /* create a new object record and a temporary leaf image */ 47 object = kmem_cache_alloc(cachefiles_object_jar, cachefiles_gfp); 48 if (!object) 49 goto nomem_object; 50 51 ASSERTCMP(object->backer, ==, NULL); 52 53 BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)); 54 atomic_set(&object->usage, 1); 55 56 fscache_object_init(&object->fscache, cookie, &cache->cache); 57 58 object->type = cookie->def->type; 59 60 /* get hold of the raw key 61 * - stick the length on the front and leave space on the back for the 62 * encoder 63 */ 64 buffer = kmalloc((2 + 512) + 3, cachefiles_gfp); 65 if (!buffer) 66 goto nomem_buffer; 67 68 keylen = cookie->def->get_key(cookie->netfs_data, buffer + 2, 512); 69 ASSERTCMP(keylen, <, 512); 70 71 *(uint16_t *)buffer = keylen; 72 ((char *)buffer)[keylen + 2] = 0; 73 ((char *)buffer)[keylen + 3] = 0; 74 ((char *)buffer)[keylen + 4] = 0; 75 76 /* turn the raw key into something that can work with as a filename */ 77 key = cachefiles_cook_key(buffer, keylen + 2, object->type); 78 if (!key) 79 goto nomem_key; 80 81 /* get hold of the auxiliary data and prepend the object type */ 82 auxdata = buffer; 83 auxlen = 0; 84 if (cookie->def->get_aux) { 85 auxlen = cookie->def->get_aux(cookie->netfs_data, 86 auxdata->data, 511); 87 ASSERTCMP(auxlen, <, 511); 88 } 89 90 auxdata->len = auxlen + 1; 91 auxdata->type = cookie->def->type; 92 93 lookup_data->auxdata = auxdata; 94 lookup_data->key = key; 95 object->lookup_data = lookup_data; 96 97 _leave(" = %p [%p]", &object->fscache, lookup_data); 98 return &object->fscache; 99 100 nomem_key: 101 kfree(buffer); 102 nomem_buffer: 103 BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)); 104 kmem_cache_free(cachefiles_object_jar, object); 105 fscache_object_destroyed(&cache->cache); 106 nomem_object: 107 kfree(lookup_data); 108 nomem_lookup_data: 109 _leave(" = -ENOMEM"); 110 return ERR_PTR(-ENOMEM); 111 } 112 113 /* 114 * attempt to look up the nominated node in this cache 115 * - return -ETIMEDOUT to be scheduled again 116 */ 117 static int cachefiles_lookup_object(struct fscache_object *_object) 118 { 119 struct cachefiles_lookup_data *lookup_data; 120 struct cachefiles_object *parent, *object; 121 struct cachefiles_cache *cache; 122 const struct cred *saved_cred; 123 int ret; 124 125 _enter("{OBJ%x}", _object->debug_id); 126 127 cache = container_of(_object->cache, struct cachefiles_cache, cache); 128 parent = container_of(_object->parent, 129 struct cachefiles_object, fscache); 130 object = container_of(_object, struct cachefiles_object, fscache); 131 lookup_data = object->lookup_data; 132 133 ASSERTCMP(lookup_data, !=, NULL); 134 135 /* look up the key, creating any missing bits */ 136 cachefiles_begin_secure(cache, &saved_cred); 137 ret = cachefiles_walk_to_object(parent, object, 138 lookup_data->key, 139 lookup_data->auxdata); 140 cachefiles_end_secure(cache, saved_cred); 141 142 /* polish off by setting the attributes of non-index files */ 143 if (ret == 0 && 144 object->fscache.cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) 145 cachefiles_attr_changed(&object->fscache); 146 147 if (ret < 0 && ret != -ETIMEDOUT) { 148 if (ret != -ENOBUFS) 149 pr_warn("Lookup failed error %d\n", ret); 150 fscache_object_lookup_error(&object->fscache); 151 } 152 153 _leave(" [%d]", ret); 154 return ret; 155 } 156 157 /* 158 * indication of lookup completion 159 */ 160 static void cachefiles_lookup_complete(struct fscache_object *_object) 161 { 162 struct cachefiles_object *object; 163 164 object = container_of(_object, struct cachefiles_object, fscache); 165 166 _enter("{OBJ%x,%p}", object->fscache.debug_id, object->lookup_data); 167 168 if (object->lookup_data) { 169 kfree(object->lookup_data->key); 170 kfree(object->lookup_data->auxdata); 171 kfree(object->lookup_data); 172 object->lookup_data = NULL; 173 } 174 } 175 176 /* 177 * increment the usage count on an inode object (may fail if unmounting) 178 */ 179 static 180 struct fscache_object *cachefiles_grab_object(struct fscache_object *_object) 181 { 182 struct cachefiles_object *object = 183 container_of(_object, struct cachefiles_object, fscache); 184 185 _enter("{OBJ%x,%d}", _object->debug_id, atomic_read(&object->usage)); 186 187 #ifdef CACHEFILES_DEBUG_SLAB 188 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000); 189 #endif 190 191 atomic_inc(&object->usage); 192 return &object->fscache; 193 } 194 195 /* 196 * update the auxiliary data for an object object on disk 197 */ 198 static void cachefiles_update_object(struct fscache_object *_object) 199 { 200 struct cachefiles_object *object; 201 struct cachefiles_xattr *auxdata; 202 struct cachefiles_cache *cache; 203 struct fscache_cookie *cookie; 204 const struct cred *saved_cred; 205 unsigned auxlen; 206 207 _enter("{OBJ%x}", _object->debug_id); 208 209 object = container_of(_object, struct cachefiles_object, fscache); 210 cache = container_of(object->fscache.cache, struct cachefiles_cache, 211 cache); 212 213 if (!fscache_use_cookie(_object)) { 214 _leave(" [relinq]"); 215 return; 216 } 217 218 cookie = object->fscache.cookie; 219 220 if (!cookie->def->get_aux) { 221 fscache_unuse_cookie(_object); 222 _leave(" [no aux]"); 223 return; 224 } 225 226 auxdata = kmalloc(2 + 512 + 3, cachefiles_gfp); 227 if (!auxdata) { 228 fscache_unuse_cookie(_object); 229 _leave(" [nomem]"); 230 return; 231 } 232 233 auxlen = cookie->def->get_aux(cookie->netfs_data, auxdata->data, 511); 234 fscache_unuse_cookie(_object); 235 ASSERTCMP(auxlen, <, 511); 236 237 auxdata->len = auxlen + 1; 238 auxdata->type = cookie->def->type; 239 240 cachefiles_begin_secure(cache, &saved_cred); 241 cachefiles_update_object_xattr(object, auxdata); 242 cachefiles_end_secure(cache, saved_cred); 243 kfree(auxdata); 244 _leave(""); 245 } 246 247 /* 248 * discard the resources pinned by an object and effect retirement if 249 * requested 250 */ 251 static void cachefiles_drop_object(struct fscache_object *_object) 252 { 253 struct cachefiles_object *object; 254 struct cachefiles_cache *cache; 255 const struct cred *saved_cred; 256 257 ASSERT(_object); 258 259 object = container_of(_object, struct cachefiles_object, fscache); 260 261 _enter("{OBJ%x,%d}", 262 object->fscache.debug_id, atomic_read(&object->usage)); 263 264 cache = container_of(object->fscache.cache, 265 struct cachefiles_cache, cache); 266 267 #ifdef CACHEFILES_DEBUG_SLAB 268 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000); 269 #endif 270 271 /* We need to tidy the object up if we did in fact manage to open it. 272 * It's possible for us to get here before the object is fully 273 * initialised if the parent goes away or the object gets retired 274 * before we set it up. 275 */ 276 if (object->dentry) { 277 /* delete retired objects */ 278 if (test_bit(FSCACHE_OBJECT_RETIRED, &object->fscache.flags) && 279 _object != cache->cache.fsdef 280 ) { 281 _debug("- retire object OBJ%x", object->fscache.debug_id); 282 cachefiles_begin_secure(cache, &saved_cred); 283 cachefiles_delete_object(cache, object); 284 cachefiles_end_secure(cache, saved_cred); 285 } 286 287 /* close the filesystem stuff attached to the object */ 288 if (object->backer != object->dentry) 289 dput(object->backer); 290 object->backer = NULL; 291 } 292 293 /* note that the object is now inactive */ 294 if (test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) { 295 write_lock(&cache->active_lock); 296 if (!test_and_clear_bit(CACHEFILES_OBJECT_ACTIVE, 297 &object->flags)) 298 BUG(); 299 rb_erase(&object->active_node, &cache->active_nodes); 300 wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE); 301 write_unlock(&cache->active_lock); 302 } 303 304 dput(object->dentry); 305 object->dentry = NULL; 306 307 _leave(""); 308 } 309 310 /* 311 * dispose of a reference to an object 312 */ 313 static void cachefiles_put_object(struct fscache_object *_object) 314 { 315 struct cachefiles_object *object; 316 struct fscache_cache *cache; 317 318 ASSERT(_object); 319 320 object = container_of(_object, struct cachefiles_object, fscache); 321 322 _enter("{OBJ%x,%d}", 323 object->fscache.debug_id, atomic_read(&object->usage)); 324 325 #ifdef CACHEFILES_DEBUG_SLAB 326 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000); 327 #endif 328 329 ASSERTIFCMP(object->fscache.parent, 330 object->fscache.parent->n_children, >, 0); 331 332 if (atomic_dec_and_test(&object->usage)) { 333 _debug("- kill object OBJ%x", object->fscache.debug_id); 334 335 ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)); 336 ASSERTCMP(object->fscache.parent, ==, NULL); 337 ASSERTCMP(object->backer, ==, NULL); 338 ASSERTCMP(object->dentry, ==, NULL); 339 ASSERTCMP(object->fscache.n_ops, ==, 0); 340 ASSERTCMP(object->fscache.n_children, ==, 0); 341 342 if (object->lookup_data) { 343 kfree(object->lookup_data->key); 344 kfree(object->lookup_data->auxdata); 345 kfree(object->lookup_data); 346 object->lookup_data = NULL; 347 } 348 349 cache = object->fscache.cache; 350 fscache_object_destroy(&object->fscache); 351 kmem_cache_free(cachefiles_object_jar, object); 352 fscache_object_destroyed(cache); 353 } 354 355 _leave(""); 356 } 357 358 /* 359 * sync a cache 360 */ 361 static void cachefiles_sync_cache(struct fscache_cache *_cache) 362 { 363 struct cachefiles_cache *cache; 364 const struct cred *saved_cred; 365 int ret; 366 367 _enter("%p", _cache); 368 369 cache = container_of(_cache, struct cachefiles_cache, cache); 370 371 /* make sure all pages pinned by operations on behalf of the netfs are 372 * written to disc */ 373 cachefiles_begin_secure(cache, &saved_cred); 374 down_read(&cache->mnt->mnt_sb->s_umount); 375 ret = sync_filesystem(cache->mnt->mnt_sb); 376 up_read(&cache->mnt->mnt_sb->s_umount); 377 cachefiles_end_secure(cache, saved_cred); 378 379 if (ret == -EIO) 380 cachefiles_io_error(cache, 381 "Attempt to sync backing fs superblock" 382 " returned error %d", 383 ret); 384 } 385 386 /* 387 * check if the backing cache is updated to FS-Cache 388 * - called by FS-Cache when evaluates if need to invalidate the cache 389 */ 390 static bool cachefiles_check_consistency(struct fscache_operation *op) 391 { 392 struct cachefiles_object *object; 393 struct cachefiles_cache *cache; 394 const struct cred *saved_cred; 395 int ret; 396 397 _enter("{OBJ%x}", op->object->debug_id); 398 399 object = container_of(op->object, struct cachefiles_object, fscache); 400 cache = container_of(object->fscache.cache, 401 struct cachefiles_cache, cache); 402 403 cachefiles_begin_secure(cache, &saved_cred); 404 ret = cachefiles_check_auxdata(object); 405 cachefiles_end_secure(cache, saved_cred); 406 407 _leave(" = %d", ret); 408 return ret; 409 } 410 411 /* 412 * notification the attributes on an object have changed 413 * - called with reads/writes excluded by FS-Cache 414 */ 415 static int cachefiles_attr_changed(struct fscache_object *_object) 416 { 417 struct cachefiles_object *object; 418 struct cachefiles_cache *cache; 419 const struct cred *saved_cred; 420 struct iattr newattrs; 421 uint64_t ni_size; 422 loff_t oi_size; 423 int ret; 424 425 _object->cookie->def->get_attr(_object->cookie->netfs_data, &ni_size); 426 427 _enter("{OBJ%x},[%llu]", 428 _object->debug_id, (unsigned long long) ni_size); 429 430 object = container_of(_object, struct cachefiles_object, fscache); 431 cache = container_of(object->fscache.cache, 432 struct cachefiles_cache, cache); 433 434 if (ni_size == object->i_size) 435 return 0; 436 437 if (!object->backer) 438 return -ENOBUFS; 439 440 ASSERT(d_is_reg(object->backer)); 441 442 fscache_set_store_limit(&object->fscache, ni_size); 443 444 oi_size = i_size_read(d_backing_inode(object->backer)); 445 if (oi_size == ni_size) 446 return 0; 447 448 cachefiles_begin_secure(cache, &saved_cred); 449 inode_lock(d_inode(object->backer)); 450 451 /* if there's an extension to a partial page at the end of the backing 452 * file, we need to discard the partial page so that we pick up new 453 * data after it */ 454 if (oi_size & ~PAGE_MASK && ni_size > oi_size) { 455 _debug("discard tail %llx", oi_size); 456 newattrs.ia_valid = ATTR_SIZE; 457 newattrs.ia_size = oi_size & PAGE_MASK; 458 ret = notify_change(object->backer, &newattrs, NULL); 459 if (ret < 0) 460 goto truncate_failed; 461 } 462 463 newattrs.ia_valid = ATTR_SIZE; 464 newattrs.ia_size = ni_size; 465 ret = notify_change(object->backer, &newattrs, NULL); 466 467 truncate_failed: 468 inode_unlock(d_inode(object->backer)); 469 cachefiles_end_secure(cache, saved_cred); 470 471 if (ret == -EIO) { 472 fscache_set_store_limit(&object->fscache, 0); 473 cachefiles_io_error_obj(object, "Size set failed"); 474 ret = -ENOBUFS; 475 } 476 477 _leave(" = %d", ret); 478 return ret; 479 } 480 481 /* 482 * Invalidate an object 483 */ 484 static void cachefiles_invalidate_object(struct fscache_operation *op) 485 { 486 struct cachefiles_object *object; 487 struct cachefiles_cache *cache; 488 const struct cred *saved_cred; 489 struct path path; 490 uint64_t ni_size; 491 int ret; 492 493 object = container_of(op->object, struct cachefiles_object, fscache); 494 cache = container_of(object->fscache.cache, 495 struct cachefiles_cache, cache); 496 497 op->object->cookie->def->get_attr(op->object->cookie->netfs_data, 498 &ni_size); 499 500 _enter("{OBJ%x},[%llu]", 501 op->object->debug_id, (unsigned long long)ni_size); 502 503 if (object->backer) { 504 ASSERT(d_is_reg(object->backer)); 505 506 fscache_set_store_limit(&object->fscache, ni_size); 507 508 path.dentry = object->backer; 509 path.mnt = cache->mnt; 510 511 cachefiles_begin_secure(cache, &saved_cred); 512 ret = vfs_truncate(&path, 0); 513 if (ret == 0) 514 ret = vfs_truncate(&path, ni_size); 515 cachefiles_end_secure(cache, saved_cred); 516 517 if (ret != 0) { 518 fscache_set_store_limit(&object->fscache, 0); 519 if (ret == -EIO) 520 cachefiles_io_error_obj(object, 521 "Invalidate failed"); 522 } 523 } 524 525 fscache_op_complete(op, true); 526 _leave(""); 527 } 528 529 /* 530 * dissociate a cache from all the pages it was backing 531 */ 532 static void cachefiles_dissociate_pages(struct fscache_cache *cache) 533 { 534 _enter(""); 535 } 536 537 const struct fscache_cache_ops cachefiles_cache_ops = { 538 .name = "cachefiles", 539 .alloc_object = cachefiles_alloc_object, 540 .lookup_object = cachefiles_lookup_object, 541 .lookup_complete = cachefiles_lookup_complete, 542 .grab_object = cachefiles_grab_object, 543 .update_object = cachefiles_update_object, 544 .invalidate_object = cachefiles_invalidate_object, 545 .drop_object = cachefiles_drop_object, 546 .put_object = cachefiles_put_object, 547 .sync_cache = cachefiles_sync_cache, 548 .attr_changed = cachefiles_attr_changed, 549 .read_or_alloc_page = cachefiles_read_or_alloc_page, 550 .read_or_alloc_pages = cachefiles_read_or_alloc_pages, 551 .allocate_page = cachefiles_allocate_page, 552 .allocate_pages = cachefiles_allocate_pages, 553 .write_page = cachefiles_write_page, 554 .uncache_page = cachefiles_uncache_page, 555 .dissociate_pages = cachefiles_dissociate_pages, 556 .check_consistency = cachefiles_check_consistency, 557 }; 558