1 /* FS-Cache interface to CacheFiles 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/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 enum fscache_obj_ref_trace why) 182 { 183 struct cachefiles_object *object = 184 container_of(_object, struct cachefiles_object, fscache); 185 int u; 186 187 _enter("{OBJ%x,%d}", _object->debug_id, atomic_read(&object->usage)); 188 189 #ifdef CACHEFILES_DEBUG_SLAB 190 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000); 191 #endif 192 193 u = atomic_inc_return(&object->usage); 194 trace_cachefiles_ref(object, _object->cookie, 195 (enum cachefiles_obj_ref_trace)why, u); 196 return &object->fscache; 197 } 198 199 /* 200 * update the auxiliary data for an object object on disk 201 */ 202 static void cachefiles_update_object(struct fscache_object *_object) 203 { 204 struct cachefiles_object *object; 205 struct cachefiles_xattr *auxdata; 206 struct cachefiles_cache *cache; 207 struct fscache_cookie *cookie; 208 const struct cred *saved_cred; 209 unsigned auxlen; 210 211 _enter("{OBJ%x}", _object->debug_id); 212 213 object = container_of(_object, struct cachefiles_object, fscache); 214 cache = container_of(object->fscache.cache, struct cachefiles_cache, 215 cache); 216 217 if (!fscache_use_cookie(_object)) { 218 _leave(" [relinq]"); 219 return; 220 } 221 222 cookie = object->fscache.cookie; 223 224 if (!cookie->def->get_aux) { 225 fscache_unuse_cookie(_object); 226 _leave(" [no aux]"); 227 return; 228 } 229 230 auxdata = kmalloc(2 + 512 + 3, cachefiles_gfp); 231 if (!auxdata) { 232 fscache_unuse_cookie(_object); 233 _leave(" [nomem]"); 234 return; 235 } 236 237 auxlen = cookie->def->get_aux(cookie->netfs_data, auxdata->data, 511); 238 fscache_unuse_cookie(_object); 239 ASSERTCMP(auxlen, <, 511); 240 241 auxdata->len = auxlen + 1; 242 auxdata->type = cookie->def->type; 243 244 cachefiles_begin_secure(cache, &saved_cred); 245 cachefiles_update_object_xattr(object, auxdata); 246 cachefiles_end_secure(cache, saved_cred); 247 kfree(auxdata); 248 _leave(""); 249 } 250 251 /* 252 * discard the resources pinned by an object and effect retirement if 253 * requested 254 */ 255 static void cachefiles_drop_object(struct fscache_object *_object) 256 { 257 struct cachefiles_object *object; 258 struct cachefiles_cache *cache; 259 const struct cred *saved_cred; 260 struct inode *inode; 261 blkcnt_t i_blocks = 0; 262 263 ASSERT(_object); 264 265 object = container_of(_object, struct cachefiles_object, fscache); 266 267 _enter("{OBJ%x,%d}", 268 object->fscache.debug_id, atomic_read(&object->usage)); 269 270 cache = container_of(object->fscache.cache, 271 struct cachefiles_cache, cache); 272 273 #ifdef CACHEFILES_DEBUG_SLAB 274 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000); 275 #endif 276 277 /* We need to tidy the object up if we did in fact manage to open it. 278 * It's possible for us to get here before the object is fully 279 * initialised if the parent goes away or the object gets retired 280 * before we set it up. 281 */ 282 if (object->dentry) { 283 /* delete retired objects */ 284 if (test_bit(FSCACHE_OBJECT_RETIRED, &object->fscache.flags) && 285 _object != cache->cache.fsdef 286 ) { 287 _debug("- retire object OBJ%x", object->fscache.debug_id); 288 inode = d_backing_inode(object->dentry); 289 if (inode) 290 i_blocks = inode->i_blocks; 291 292 cachefiles_begin_secure(cache, &saved_cred); 293 cachefiles_delete_object(cache, object); 294 cachefiles_end_secure(cache, saved_cred); 295 } 296 297 /* close the filesystem stuff attached to the object */ 298 if (object->backer != object->dentry) 299 dput(object->backer); 300 object->backer = NULL; 301 } 302 303 /* note that the object is now inactive */ 304 if (test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) 305 cachefiles_mark_object_inactive(cache, object, i_blocks); 306 307 dput(object->dentry); 308 object->dentry = NULL; 309 310 _leave(""); 311 } 312 313 /* 314 * dispose of a reference to an object 315 */ 316 static void cachefiles_put_object(struct fscache_object *_object, 317 enum fscache_obj_ref_trace why) 318 { 319 struct cachefiles_object *object; 320 struct fscache_cache *cache; 321 int u; 322 323 ASSERT(_object); 324 325 object = container_of(_object, struct cachefiles_object, fscache); 326 327 _enter("{OBJ%x,%d}", 328 object->fscache.debug_id, atomic_read(&object->usage)); 329 330 #ifdef CACHEFILES_DEBUG_SLAB 331 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000); 332 #endif 333 334 ASSERTIFCMP(object->fscache.parent, 335 object->fscache.parent->n_children, >, 0); 336 337 u = atomic_dec_return(&object->usage); 338 trace_cachefiles_ref(object, _object->cookie, 339 (enum cachefiles_obj_ref_trace)why, u); 340 ASSERTCMP(u, !=, -1); 341 if (u == 0) { 342 _debug("- kill object OBJ%x", object->fscache.debug_id); 343 344 ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)); 345 ASSERTCMP(object->fscache.parent, ==, NULL); 346 ASSERTCMP(object->backer, ==, NULL); 347 ASSERTCMP(object->dentry, ==, NULL); 348 ASSERTCMP(object->fscache.n_ops, ==, 0); 349 ASSERTCMP(object->fscache.n_children, ==, 0); 350 351 if (object->lookup_data) { 352 kfree(object->lookup_data->key); 353 kfree(object->lookup_data->auxdata); 354 kfree(object->lookup_data); 355 object->lookup_data = NULL; 356 } 357 358 cache = object->fscache.cache; 359 fscache_object_destroy(&object->fscache); 360 kmem_cache_free(cachefiles_object_jar, object); 361 fscache_object_destroyed(cache); 362 } 363 364 _leave(""); 365 } 366 367 /* 368 * sync a cache 369 */ 370 static void cachefiles_sync_cache(struct fscache_cache *_cache) 371 { 372 struct cachefiles_cache *cache; 373 const struct cred *saved_cred; 374 int ret; 375 376 _enter("%p", _cache); 377 378 cache = container_of(_cache, struct cachefiles_cache, cache); 379 380 /* make sure all pages pinned by operations on behalf of the netfs are 381 * written to disc */ 382 cachefiles_begin_secure(cache, &saved_cred); 383 down_read(&cache->mnt->mnt_sb->s_umount); 384 ret = sync_filesystem(cache->mnt->mnt_sb); 385 up_read(&cache->mnt->mnt_sb->s_umount); 386 cachefiles_end_secure(cache, saved_cred); 387 388 if (ret == -EIO) 389 cachefiles_io_error(cache, 390 "Attempt to sync backing fs superblock" 391 " returned error %d", 392 ret); 393 } 394 395 /* 396 * check if the backing cache is updated to FS-Cache 397 * - called by FS-Cache when evaluates if need to invalidate the cache 398 */ 399 static int cachefiles_check_consistency(struct fscache_operation *op) 400 { 401 struct cachefiles_object *object; 402 struct cachefiles_cache *cache; 403 const struct cred *saved_cred; 404 int ret; 405 406 _enter("{OBJ%x}", op->object->debug_id); 407 408 object = container_of(op->object, struct cachefiles_object, fscache); 409 cache = container_of(object->fscache.cache, 410 struct cachefiles_cache, cache); 411 412 cachefiles_begin_secure(cache, &saved_cred); 413 ret = cachefiles_check_auxdata(object); 414 cachefiles_end_secure(cache, saved_cred); 415 416 _leave(" = %d", ret); 417 return ret; 418 } 419 420 /* 421 * notification the attributes on an object have changed 422 * - called with reads/writes excluded by FS-Cache 423 */ 424 static int cachefiles_attr_changed(struct fscache_object *_object) 425 { 426 struct cachefiles_object *object; 427 struct cachefiles_cache *cache; 428 const struct cred *saved_cred; 429 struct iattr newattrs; 430 uint64_t ni_size; 431 loff_t oi_size; 432 int ret; 433 434 _object->cookie->def->get_attr(_object->cookie->netfs_data, &ni_size); 435 436 _enter("{OBJ%x},[%llu]", 437 _object->debug_id, (unsigned long long) ni_size); 438 439 object = container_of(_object, struct cachefiles_object, fscache); 440 cache = container_of(object->fscache.cache, 441 struct cachefiles_cache, cache); 442 443 if (ni_size == object->i_size) 444 return 0; 445 446 if (!object->backer) 447 return -ENOBUFS; 448 449 ASSERT(d_is_reg(object->backer)); 450 451 fscache_set_store_limit(&object->fscache, ni_size); 452 453 oi_size = i_size_read(d_backing_inode(object->backer)); 454 if (oi_size == ni_size) 455 return 0; 456 457 cachefiles_begin_secure(cache, &saved_cred); 458 inode_lock(d_inode(object->backer)); 459 460 /* if there's an extension to a partial page at the end of the backing 461 * file, we need to discard the partial page so that we pick up new 462 * data after it */ 463 if (oi_size & ~PAGE_MASK && ni_size > oi_size) { 464 _debug("discard tail %llx", oi_size); 465 newattrs.ia_valid = ATTR_SIZE; 466 newattrs.ia_size = oi_size & PAGE_MASK; 467 ret = notify_change(object->backer, &newattrs, NULL); 468 if (ret < 0) 469 goto truncate_failed; 470 } 471 472 newattrs.ia_valid = ATTR_SIZE; 473 newattrs.ia_size = ni_size; 474 ret = notify_change(object->backer, &newattrs, NULL); 475 476 truncate_failed: 477 inode_unlock(d_inode(object->backer)); 478 cachefiles_end_secure(cache, saved_cred); 479 480 if (ret == -EIO) { 481 fscache_set_store_limit(&object->fscache, 0); 482 cachefiles_io_error_obj(object, "Size set failed"); 483 ret = -ENOBUFS; 484 } 485 486 _leave(" = %d", ret); 487 return ret; 488 } 489 490 /* 491 * Invalidate an object 492 */ 493 static void cachefiles_invalidate_object(struct fscache_operation *op) 494 { 495 struct cachefiles_object *object; 496 struct cachefiles_cache *cache; 497 const struct cred *saved_cred; 498 struct path path; 499 uint64_t ni_size; 500 int ret; 501 502 object = container_of(op->object, struct cachefiles_object, fscache); 503 cache = container_of(object->fscache.cache, 504 struct cachefiles_cache, cache); 505 506 op->object->cookie->def->get_attr(op->object->cookie->netfs_data, 507 &ni_size); 508 509 _enter("{OBJ%x},[%llu]", 510 op->object->debug_id, (unsigned long long)ni_size); 511 512 if (object->backer) { 513 ASSERT(d_is_reg(object->backer)); 514 515 fscache_set_store_limit(&object->fscache, ni_size); 516 517 path.dentry = object->backer; 518 path.mnt = cache->mnt; 519 520 cachefiles_begin_secure(cache, &saved_cred); 521 ret = vfs_truncate(&path, 0); 522 if (ret == 0) 523 ret = vfs_truncate(&path, ni_size); 524 cachefiles_end_secure(cache, saved_cred); 525 526 if (ret != 0) { 527 fscache_set_store_limit(&object->fscache, 0); 528 if (ret == -EIO) 529 cachefiles_io_error_obj(object, 530 "Invalidate failed"); 531 } 532 } 533 534 fscache_op_complete(op, true); 535 _leave(""); 536 } 537 538 /* 539 * dissociate a cache from all the pages it was backing 540 */ 541 static void cachefiles_dissociate_pages(struct fscache_cache *cache) 542 { 543 _enter(""); 544 } 545 546 const struct fscache_cache_ops cachefiles_cache_ops = { 547 .name = "cachefiles", 548 .alloc_object = cachefiles_alloc_object, 549 .lookup_object = cachefiles_lookup_object, 550 .lookup_complete = cachefiles_lookup_complete, 551 .grab_object = cachefiles_grab_object, 552 .update_object = cachefiles_update_object, 553 .invalidate_object = cachefiles_invalidate_object, 554 .drop_object = cachefiles_drop_object, 555 .put_object = cachefiles_put_object, 556 .sync_cache = cachefiles_sync_cache, 557 .attr_changed = cachefiles_attr_changed, 558 .read_or_alloc_page = cachefiles_read_or_alloc_page, 559 .read_or_alloc_pages = cachefiles_read_or_alloc_pages, 560 .allocate_page = cachefiles_allocate_page, 561 .allocate_pages = cachefiles_allocate_pages, 562 .write_page = cachefiles_write_page, 563 .uncache_page = cachefiles_uncache_page, 564 .dissociate_pages = cachefiles_dissociate_pages, 565 .check_consistency = cachefiles_check_consistency, 566 }; 567