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