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 struct inode *inode; 257 blkcnt_t i_blocks = 0; 258 259 ASSERT(_object); 260 261 object = container_of(_object, struct cachefiles_object, fscache); 262 263 _enter("{OBJ%x,%d}", 264 object->fscache.debug_id, atomic_read(&object->usage)); 265 266 cache = container_of(object->fscache.cache, 267 struct cachefiles_cache, cache); 268 269 #ifdef CACHEFILES_DEBUG_SLAB 270 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000); 271 #endif 272 273 /* We need to tidy the object up if we did in fact manage to open it. 274 * It's possible for us to get here before the object is fully 275 * initialised if the parent goes away or the object gets retired 276 * before we set it up. 277 */ 278 if (object->dentry) { 279 /* delete retired objects */ 280 if (test_bit(FSCACHE_OBJECT_RETIRED, &object->fscache.flags) && 281 _object != cache->cache.fsdef 282 ) { 283 _debug("- retire object OBJ%x", object->fscache.debug_id); 284 inode = d_backing_inode(object->dentry); 285 if (inode) 286 i_blocks = inode->i_blocks; 287 288 cachefiles_begin_secure(cache, &saved_cred); 289 cachefiles_delete_object(cache, object); 290 cachefiles_end_secure(cache, saved_cred); 291 } 292 293 /* close the filesystem stuff attached to the object */ 294 if (object->backer != object->dentry) 295 dput(object->backer); 296 object->backer = NULL; 297 } 298 299 /* note that the object is now inactive */ 300 if (test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) 301 cachefiles_mark_object_inactive(cache, object, i_blocks); 302 303 dput(object->dentry); 304 object->dentry = NULL; 305 306 _leave(""); 307 } 308 309 /* 310 * dispose of a reference to an object 311 */ 312 static void cachefiles_put_object(struct fscache_object *_object) 313 { 314 struct cachefiles_object *object; 315 struct fscache_cache *cache; 316 317 ASSERT(_object); 318 319 object = container_of(_object, struct cachefiles_object, fscache); 320 321 _enter("{OBJ%x,%d}", 322 object->fscache.debug_id, atomic_read(&object->usage)); 323 324 #ifdef CACHEFILES_DEBUG_SLAB 325 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000); 326 #endif 327 328 ASSERTIFCMP(object->fscache.parent, 329 object->fscache.parent->n_children, >, 0); 330 331 if (atomic_dec_and_test(&object->usage)) { 332 _debug("- kill object OBJ%x", object->fscache.debug_id); 333 334 ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)); 335 ASSERTCMP(object->fscache.parent, ==, NULL); 336 ASSERTCMP(object->backer, ==, NULL); 337 ASSERTCMP(object->dentry, ==, NULL); 338 ASSERTCMP(object->fscache.n_ops, ==, 0); 339 ASSERTCMP(object->fscache.n_children, ==, 0); 340 341 if (object->lookup_data) { 342 kfree(object->lookup_data->key); 343 kfree(object->lookup_data->auxdata); 344 kfree(object->lookup_data); 345 object->lookup_data = NULL; 346 } 347 348 cache = object->fscache.cache; 349 fscache_object_destroy(&object->fscache); 350 kmem_cache_free(cachefiles_object_jar, object); 351 fscache_object_destroyed(cache); 352 } 353 354 _leave(""); 355 } 356 357 /* 358 * sync a cache 359 */ 360 static void cachefiles_sync_cache(struct fscache_cache *_cache) 361 { 362 struct cachefiles_cache *cache; 363 const struct cred *saved_cred; 364 int ret; 365 366 _enter("%p", _cache); 367 368 cache = container_of(_cache, struct cachefiles_cache, cache); 369 370 /* make sure all pages pinned by operations on behalf of the netfs are 371 * written to disc */ 372 cachefiles_begin_secure(cache, &saved_cred); 373 down_read(&cache->mnt->mnt_sb->s_umount); 374 ret = sync_filesystem(cache->mnt->mnt_sb); 375 up_read(&cache->mnt->mnt_sb->s_umount); 376 cachefiles_end_secure(cache, saved_cred); 377 378 if (ret == -EIO) 379 cachefiles_io_error(cache, 380 "Attempt to sync backing fs superblock" 381 " returned error %d", 382 ret); 383 } 384 385 /* 386 * check if the backing cache is updated to FS-Cache 387 * - called by FS-Cache when evaluates if need to invalidate the cache 388 */ 389 static int cachefiles_check_consistency(struct fscache_operation *op) 390 { 391 struct cachefiles_object *object; 392 struct cachefiles_cache *cache; 393 const struct cred *saved_cred; 394 int ret; 395 396 _enter("{OBJ%x}", op->object->debug_id); 397 398 object = container_of(op->object, struct cachefiles_object, fscache); 399 cache = container_of(object->fscache.cache, 400 struct cachefiles_cache, cache); 401 402 cachefiles_begin_secure(cache, &saved_cred); 403 ret = cachefiles_check_auxdata(object); 404 cachefiles_end_secure(cache, saved_cred); 405 406 _leave(" = %d", ret); 407 return ret; 408 } 409 410 /* 411 * notification the attributes on an object have changed 412 * - called with reads/writes excluded by FS-Cache 413 */ 414 static int cachefiles_attr_changed(struct fscache_object *_object) 415 { 416 struct cachefiles_object *object; 417 struct cachefiles_cache *cache; 418 const struct cred *saved_cred; 419 struct iattr newattrs; 420 uint64_t ni_size; 421 loff_t oi_size; 422 int ret; 423 424 _object->cookie->def->get_attr(_object->cookie->netfs_data, &ni_size); 425 426 _enter("{OBJ%x},[%llu]", 427 _object->debug_id, (unsigned long long) ni_size); 428 429 object = container_of(_object, struct cachefiles_object, fscache); 430 cache = container_of(object->fscache.cache, 431 struct cachefiles_cache, cache); 432 433 if (ni_size == object->i_size) 434 return 0; 435 436 if (!object->backer) 437 return -ENOBUFS; 438 439 ASSERT(d_is_reg(object->backer)); 440 441 fscache_set_store_limit(&object->fscache, ni_size); 442 443 oi_size = i_size_read(d_backing_inode(object->backer)); 444 if (oi_size == ni_size) 445 return 0; 446 447 cachefiles_begin_secure(cache, &saved_cred); 448 inode_lock(d_inode(object->backer)); 449 450 /* if there's an extension to a partial page at the end of the backing 451 * file, we need to discard the partial page so that we pick up new 452 * data after it */ 453 if (oi_size & ~PAGE_MASK && ni_size > oi_size) { 454 _debug("discard tail %llx", oi_size); 455 newattrs.ia_valid = ATTR_SIZE; 456 newattrs.ia_size = oi_size & PAGE_MASK; 457 ret = notify_change(object->backer, &newattrs, NULL); 458 if (ret < 0) 459 goto truncate_failed; 460 } 461 462 newattrs.ia_valid = ATTR_SIZE; 463 newattrs.ia_size = ni_size; 464 ret = notify_change(object->backer, &newattrs, NULL); 465 466 truncate_failed: 467 inode_unlock(d_inode(object->backer)); 468 cachefiles_end_secure(cache, saved_cred); 469 470 if (ret == -EIO) { 471 fscache_set_store_limit(&object->fscache, 0); 472 cachefiles_io_error_obj(object, "Size set failed"); 473 ret = -ENOBUFS; 474 } 475 476 _leave(" = %d", ret); 477 return ret; 478 } 479 480 /* 481 * Invalidate an object 482 */ 483 static void cachefiles_invalidate_object(struct fscache_operation *op) 484 { 485 struct cachefiles_object *object; 486 struct cachefiles_cache *cache; 487 const struct cred *saved_cred; 488 struct path path; 489 uint64_t ni_size; 490 int ret; 491 492 object = container_of(op->object, struct cachefiles_object, fscache); 493 cache = container_of(object->fscache.cache, 494 struct cachefiles_cache, cache); 495 496 op->object->cookie->def->get_attr(op->object->cookie->netfs_data, 497 &ni_size); 498 499 _enter("{OBJ%x},[%llu]", 500 op->object->debug_id, (unsigned long long)ni_size); 501 502 if (object->backer) { 503 ASSERT(d_is_reg(object->backer)); 504 505 fscache_set_store_limit(&object->fscache, ni_size); 506 507 path.dentry = object->backer; 508 path.mnt = cache->mnt; 509 510 cachefiles_begin_secure(cache, &saved_cred); 511 ret = vfs_truncate(&path, 0); 512 if (ret == 0) 513 ret = vfs_truncate(&path, ni_size); 514 cachefiles_end_secure(cache, saved_cred); 515 516 if (ret != 0) { 517 fscache_set_store_limit(&object->fscache, 0); 518 if (ret == -EIO) 519 cachefiles_io_error_obj(object, 520 "Invalidate failed"); 521 } 522 } 523 524 fscache_op_complete(op, true); 525 _leave(""); 526 } 527 528 /* 529 * dissociate a cache from all the pages it was backing 530 */ 531 static void cachefiles_dissociate_pages(struct fscache_cache *cache) 532 { 533 _enter(""); 534 } 535 536 const struct fscache_cache_ops cachefiles_cache_ops = { 537 .name = "cachefiles", 538 .alloc_object = cachefiles_alloc_object, 539 .lookup_object = cachefiles_lookup_object, 540 .lookup_complete = cachefiles_lookup_complete, 541 .grab_object = cachefiles_grab_object, 542 .update_object = cachefiles_update_object, 543 .invalidate_object = cachefiles_invalidate_object, 544 .drop_object = cachefiles_drop_object, 545 .put_object = cachefiles_put_object, 546 .sync_cache = cachefiles_sync_cache, 547 .attr_changed = cachefiles_attr_changed, 548 .read_or_alloc_page = cachefiles_read_or_alloc_page, 549 .read_or_alloc_pages = cachefiles_read_or_alloc_pages, 550 .allocate_page = cachefiles_allocate_page, 551 .allocate_pages = cachefiles_allocate_pages, 552 .write_page = cachefiles_write_page, 553 .uncache_page = cachefiles_uncache_page, 554 .dissociate_pages = cachefiles_dissociate_pages, 555 .check_consistency = cachefiles_check_consistency, 556 }; 557