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/mount.h> 13 #include <linux/buffer_head.h> 14 #include "internal.h" 15 16 #define list_to_page(head) (list_entry((head)->prev, struct page, lru)) 17 18 struct cachefiles_lookup_data { 19 struct cachefiles_xattr *auxdata; /* auxiliary data */ 20 char *key; /* key path */ 21 }; 22 23 static int cachefiles_attr_changed(struct fscache_object *_object); 24 25 /* 26 * allocate an object record for a cookie lookup and prepare the lookup data 27 */ 28 static struct fscache_object *cachefiles_alloc_object( 29 struct fscache_cache *_cache, 30 struct fscache_cookie *cookie) 31 { 32 struct cachefiles_lookup_data *lookup_data; 33 struct cachefiles_object *object; 34 struct cachefiles_cache *cache; 35 struct cachefiles_xattr *auxdata; 36 unsigned keylen, auxlen; 37 void *buffer; 38 char *key; 39 40 cache = container_of(_cache, struct cachefiles_cache, cache); 41 42 _enter("{%s},%p,", cache->cache.identifier, cookie); 43 44 lookup_data = kmalloc(sizeof(*lookup_data), GFP_KERNEL); 45 if (!lookup_data) 46 goto nomem_lookup_data; 47 48 /* create a new object record and a temporary leaf image */ 49 object = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL); 50 if (!object) 51 goto nomem_object; 52 53 ASSERTCMP(object->backer, ==, NULL); 54 55 BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)); 56 atomic_set(&object->usage, 1); 57 58 fscache_object_init(&object->fscache, cookie, &cache->cache); 59 60 object->type = cookie->def->type; 61 62 /* get hold of the raw key 63 * - stick the length on the front and leave space on the back for the 64 * encoder 65 */ 66 buffer = kmalloc((2 + 512) + 3, GFP_KERNEL); 67 if (!buffer) 68 goto nomem_buffer; 69 70 keylen = cookie->def->get_key(cookie->netfs_data, buffer + 2, 512); 71 ASSERTCMP(keylen, <, 512); 72 73 *(uint16_t *)buffer = keylen; 74 ((char *)buffer)[keylen + 2] = 0; 75 ((char *)buffer)[keylen + 3] = 0; 76 ((char *)buffer)[keylen + 4] = 0; 77 78 /* turn the raw key into something that can work with as a filename */ 79 key = cachefiles_cook_key(buffer, keylen + 2, object->type); 80 if (!key) 81 goto nomem_key; 82 83 /* get hold of the auxiliary data and prepend the object type */ 84 auxdata = buffer; 85 auxlen = 0; 86 if (cookie->def->get_aux) { 87 auxlen = cookie->def->get_aux(cookie->netfs_data, 88 auxdata->data, 511); 89 ASSERTCMP(auxlen, <, 511); 90 } 91 92 auxdata->len = auxlen + 1; 93 auxdata->type = cookie->def->type; 94 95 lookup_data->auxdata = auxdata; 96 lookup_data->key = key; 97 object->lookup_data = lookup_data; 98 99 _leave(" = %p [%p]", &object->fscache, lookup_data); 100 return &object->fscache; 101 102 nomem_key: 103 kfree(buffer); 104 nomem_buffer: 105 BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)); 106 kmem_cache_free(cachefiles_object_jar, object); 107 fscache_object_destroyed(&cache->cache); 108 nomem_object: 109 kfree(lookup_data); 110 nomem_lookup_data: 111 _leave(" = -ENOMEM"); 112 return ERR_PTR(-ENOMEM); 113 } 114 115 /* 116 * attempt to look up the nominated node in this cache 117 */ 118 static void cachefiles_lookup_object(struct fscache_object *_object) 119 { 120 struct cachefiles_lookup_data *lookup_data; 121 struct cachefiles_object *parent, *object; 122 struct cachefiles_cache *cache; 123 const struct cred *saved_cred; 124 int ret; 125 126 _enter("{OBJ%x}", _object->debug_id); 127 128 cache = container_of(_object->cache, struct cachefiles_cache, cache); 129 parent = container_of(_object->parent, 130 struct cachefiles_object, fscache); 131 object = container_of(_object, struct cachefiles_object, fscache); 132 lookup_data = object->lookup_data; 133 134 ASSERTCMP(lookup_data, !=, NULL); 135 136 /* look up the key, creating any missing bits */ 137 cachefiles_begin_secure(cache, &saved_cred); 138 ret = cachefiles_walk_to_object(parent, object, 139 lookup_data->key, 140 lookup_data->auxdata); 141 cachefiles_end_secure(cache, saved_cred); 142 143 /* polish off by setting the attributes of non-index files */ 144 if (ret == 0 && 145 object->fscache.cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) 146 cachefiles_attr_changed(&object->fscache); 147 148 if (ret < 0) { 149 printk(KERN_WARNING "CacheFiles: Lookup failed error %d\n", 150 ret); 151 fscache_object_lookup_error(&object->fscache); 152 } 153 154 _leave(" [%d]", 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 auxilliary 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 cookie = object->fscache.cookie; 213 214 if (!cookie->def->get_aux) { 215 _leave(" [no aux]"); 216 return; 217 } 218 219 auxdata = kmalloc(2 + 512 + 3, GFP_KERNEL); 220 if (!auxdata) { 221 _leave(" [nomem]"); 222 return; 223 } 224 225 auxlen = cookie->def->get_aux(cookie->netfs_data, auxdata->data, 511); 226 ASSERTCMP(auxlen, <, 511); 227 228 auxdata->len = auxlen + 1; 229 auxdata->type = cookie->def->type; 230 231 cachefiles_begin_secure(cache, &saved_cred); 232 cachefiles_update_object_xattr(object, auxdata); 233 cachefiles_end_secure(cache, saved_cred); 234 kfree(auxdata); 235 _leave(""); 236 } 237 238 /* 239 * discard the resources pinned by an object and effect retirement if 240 * requested 241 */ 242 static void cachefiles_drop_object(struct fscache_object *_object) 243 { 244 struct cachefiles_object *object; 245 struct cachefiles_cache *cache; 246 const struct cred *saved_cred; 247 248 ASSERT(_object); 249 250 object = container_of(_object, struct cachefiles_object, fscache); 251 252 _enter("{OBJ%x,%d}", 253 object->fscache.debug_id, atomic_read(&object->usage)); 254 255 cache = container_of(object->fscache.cache, 256 struct cachefiles_cache, cache); 257 258 #ifdef CACHEFILES_DEBUG_SLAB 259 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000); 260 #endif 261 262 /* delete retired objects */ 263 if (object->fscache.state == FSCACHE_OBJECT_RECYCLING && 264 _object != cache->cache.fsdef 265 ) { 266 _debug("- retire object OBJ%x", object->fscache.debug_id); 267 cachefiles_begin_secure(cache, &saved_cred); 268 cachefiles_delete_object(cache, object); 269 cachefiles_end_secure(cache, saved_cred); 270 } 271 272 /* close the filesystem stuff attached to the object */ 273 if (object->backer != object->dentry) 274 dput(object->backer); 275 object->backer = NULL; 276 277 /* note that the object is now inactive */ 278 if (test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) { 279 write_lock(&cache->active_lock); 280 if (!test_and_clear_bit(CACHEFILES_OBJECT_ACTIVE, 281 &object->flags)) 282 BUG(); 283 rb_erase(&object->active_node, &cache->active_nodes); 284 wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE); 285 write_unlock(&cache->active_lock); 286 } 287 288 dput(object->dentry); 289 object->dentry = NULL; 290 291 _leave(""); 292 } 293 294 /* 295 * dispose of a reference to an object 296 */ 297 static void cachefiles_put_object(struct fscache_object *_object) 298 { 299 struct cachefiles_object *object; 300 struct fscache_cache *cache; 301 302 ASSERT(_object); 303 304 object = container_of(_object, struct cachefiles_object, fscache); 305 306 _enter("{OBJ%x,%d}", 307 object->fscache.debug_id, atomic_read(&object->usage)); 308 309 #ifdef CACHEFILES_DEBUG_SLAB 310 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000); 311 #endif 312 313 ASSERTIFCMP(object->fscache.parent, 314 object->fscache.parent->n_children, >, 0); 315 316 if (atomic_dec_and_test(&object->usage)) { 317 _debug("- kill object OBJ%x", object->fscache.debug_id); 318 319 ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)); 320 ASSERTCMP(object->fscache.parent, ==, NULL); 321 ASSERTCMP(object->backer, ==, NULL); 322 ASSERTCMP(object->dentry, ==, NULL); 323 ASSERTCMP(object->fscache.n_ops, ==, 0); 324 ASSERTCMP(object->fscache.n_children, ==, 0); 325 326 if (object->lookup_data) { 327 kfree(object->lookup_data->key); 328 kfree(object->lookup_data->auxdata); 329 kfree(object->lookup_data); 330 object->lookup_data = NULL; 331 } 332 333 cache = object->fscache.cache; 334 kmem_cache_free(cachefiles_object_jar, object); 335 fscache_object_destroyed(cache); 336 } 337 338 _leave(""); 339 } 340 341 /* 342 * sync a cache 343 */ 344 static void cachefiles_sync_cache(struct fscache_cache *_cache) 345 { 346 struct cachefiles_cache *cache; 347 const struct cred *saved_cred; 348 int ret; 349 350 _enter("%p", _cache); 351 352 cache = container_of(_cache, struct cachefiles_cache, cache); 353 354 /* make sure all pages pinned by operations on behalf of the netfs are 355 * written to disc */ 356 cachefiles_begin_secure(cache, &saved_cred); 357 down_read(&cache->mnt->mnt_sb->s_umount); 358 ret = sync_filesystem(cache->mnt->mnt_sb); 359 up_read(&cache->mnt->mnt_sb->s_umount); 360 cachefiles_end_secure(cache, saved_cred); 361 362 if (ret == -EIO) 363 cachefiles_io_error(cache, 364 "Attempt to sync backing fs superblock" 365 " returned error %d", 366 ret); 367 } 368 369 /* 370 * notification the attributes on an object have changed 371 * - called with reads/writes excluded by FS-Cache 372 */ 373 static int cachefiles_attr_changed(struct fscache_object *_object) 374 { 375 struct cachefiles_object *object; 376 struct cachefiles_cache *cache; 377 const struct cred *saved_cred; 378 struct iattr newattrs; 379 uint64_t ni_size; 380 loff_t oi_size; 381 int ret; 382 383 _object->cookie->def->get_attr(_object->cookie->netfs_data, &ni_size); 384 385 _enter("{OBJ%x},[%llu]", 386 _object->debug_id, (unsigned long long) ni_size); 387 388 object = container_of(_object, struct cachefiles_object, fscache); 389 cache = container_of(object->fscache.cache, 390 struct cachefiles_cache, cache); 391 392 if (ni_size == object->i_size) 393 return 0; 394 395 if (!object->backer) 396 return -ENOBUFS; 397 398 ASSERT(S_ISREG(object->backer->d_inode->i_mode)); 399 400 fscache_set_store_limit(&object->fscache, ni_size); 401 402 oi_size = i_size_read(object->backer->d_inode); 403 if (oi_size == ni_size) 404 return 0; 405 406 newattrs.ia_size = ni_size; 407 newattrs.ia_valid = ATTR_SIZE; 408 409 cachefiles_begin_secure(cache, &saved_cred); 410 mutex_lock(&object->backer->d_inode->i_mutex); 411 ret = notify_change(object->backer, &newattrs); 412 mutex_unlock(&object->backer->d_inode->i_mutex); 413 cachefiles_end_secure(cache, saved_cred); 414 415 if (ret == -EIO) { 416 fscache_set_store_limit(&object->fscache, 0); 417 cachefiles_io_error_obj(object, "Size set failed"); 418 ret = -ENOBUFS; 419 } 420 421 _leave(" = %d", ret); 422 return ret; 423 } 424 425 /* 426 * dissociate a cache from all the pages it was backing 427 */ 428 static void cachefiles_dissociate_pages(struct fscache_cache *cache) 429 { 430 _enter(""); 431 } 432 433 const struct fscache_cache_ops cachefiles_cache_ops = { 434 .name = "cachefiles", 435 .alloc_object = cachefiles_alloc_object, 436 .lookup_object = cachefiles_lookup_object, 437 .lookup_complete = cachefiles_lookup_complete, 438 .grab_object = cachefiles_grab_object, 439 .update_object = cachefiles_update_object, 440 .drop_object = cachefiles_drop_object, 441 .put_object = cachefiles_put_object, 442 .sync_cache = cachefiles_sync_cache, 443 .attr_changed = cachefiles_attr_changed, 444 .read_or_alloc_page = cachefiles_read_or_alloc_page, 445 .read_or_alloc_pages = cachefiles_read_or_alloc_pages, 446 .allocate_page = cachefiles_allocate_page, 447 .allocate_pages = cachefiles_allocate_pages, 448 .write_page = cachefiles_write_page, 449 .uncache_page = cachefiles_uncache_page, 450 .dissociate_pages = cachefiles_dissociate_pages, 451 }; 452