interface.c revision ff01bb4832651c6d25ac509a06a10fcbd75c461c
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#define list_to_page(head) (list_entry((head)->prev, struct page, lru)) 17 18struct cachefiles_lookup_data { 19 struct cachefiles_xattr *auxdata; /* auxiliary data */ 20 char *key; /* key path */ 21}; 22 23static 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 */ 28static 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 102nomem_key: 103 kfree(buffer); 104nomem_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); 108nomem_object: 109 kfree(lookup_data); 110nomem_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 * - return -ETIMEDOUT to be scheduled again 118 */ 119static int cachefiles_lookup_object(struct fscache_object *_object) 120{ 121 struct cachefiles_lookup_data *lookup_data; 122 struct cachefiles_object *parent, *object; 123 struct cachefiles_cache *cache; 124 const struct cred *saved_cred; 125 int ret; 126 127 _enter("{OBJ%x}", _object->debug_id); 128 129 cache = container_of(_object->cache, struct cachefiles_cache, cache); 130 parent = container_of(_object->parent, 131 struct cachefiles_object, fscache); 132 object = container_of(_object, struct cachefiles_object, fscache); 133 lookup_data = object->lookup_data; 134 135 ASSERTCMP(lookup_data, !=, NULL); 136 137 /* look up the key, creating any missing bits */ 138 cachefiles_begin_secure(cache, &saved_cred); 139 ret = cachefiles_walk_to_object(parent, object, 140 lookup_data->key, 141 lookup_data->auxdata); 142 cachefiles_end_secure(cache, saved_cred); 143 144 /* polish off by setting the attributes of non-index files */ 145 if (ret == 0 && 146 object->fscache.cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX) 147 cachefiles_attr_changed(&object->fscache); 148 149 if (ret < 0 && ret != -ETIMEDOUT) { 150 if (ret != -ENOBUFS) 151 printk(KERN_WARNING 152 "CacheFiles: Lookup failed error %d\n", ret); 153 fscache_object_lookup_error(&object->fscache); 154 } 155 156 _leave(" [%d]", ret); 157 return ret; 158} 159 160/* 161 * indication of lookup completion 162 */ 163static void cachefiles_lookup_complete(struct fscache_object *_object) 164{ 165 struct cachefiles_object *object; 166 167 object = container_of(_object, struct cachefiles_object, fscache); 168 169 _enter("{OBJ%x,%p}", object->fscache.debug_id, object->lookup_data); 170 171 if (object->lookup_data) { 172 kfree(object->lookup_data->key); 173 kfree(object->lookup_data->auxdata); 174 kfree(object->lookup_data); 175 object->lookup_data = NULL; 176 } 177} 178 179/* 180 * increment the usage count on an inode object (may fail if unmounting) 181 */ 182static 183struct fscache_object *cachefiles_grab_object(struct fscache_object *_object) 184{ 185 struct cachefiles_object *object = 186 container_of(_object, struct cachefiles_object, fscache); 187 188 _enter("{OBJ%x,%d}", _object->debug_id, atomic_read(&object->usage)); 189 190#ifdef CACHEFILES_DEBUG_SLAB 191 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000); 192#endif 193 194 atomic_inc(&object->usage); 195 return &object->fscache; 196} 197 198/* 199 * update the auxiliary data for an object object on disk 200 */ 201static void cachefiles_update_object(struct fscache_object *_object) 202{ 203 struct cachefiles_object *object; 204 struct cachefiles_xattr *auxdata; 205 struct cachefiles_cache *cache; 206 struct fscache_cookie *cookie; 207 const struct cred *saved_cred; 208 unsigned auxlen; 209 210 _enter("{OBJ%x}", _object->debug_id); 211 212 object = container_of(_object, struct cachefiles_object, fscache); 213 cache = container_of(object->fscache.cache, struct cachefiles_cache, 214 cache); 215 cookie = object->fscache.cookie; 216 217 if (!cookie->def->get_aux) { 218 _leave(" [no aux]"); 219 return; 220 } 221 222 auxdata = kmalloc(2 + 512 + 3, GFP_KERNEL); 223 if (!auxdata) { 224 _leave(" [nomem]"); 225 return; 226 } 227 228 auxlen = cookie->def->get_aux(cookie->netfs_data, auxdata->data, 511); 229 ASSERTCMP(auxlen, <, 511); 230 231 auxdata->len = auxlen + 1; 232 auxdata->type = cookie->def->type; 233 234 cachefiles_begin_secure(cache, &saved_cred); 235 cachefiles_update_object_xattr(object, auxdata); 236 cachefiles_end_secure(cache, saved_cred); 237 kfree(auxdata); 238 _leave(""); 239} 240 241/* 242 * discard the resources pinned by an object and effect retirement if 243 * requested 244 */ 245static void cachefiles_drop_object(struct fscache_object *_object) 246{ 247 struct cachefiles_object *object; 248 struct cachefiles_cache *cache; 249 const struct cred *saved_cred; 250 251 ASSERT(_object); 252 253 object = container_of(_object, struct cachefiles_object, fscache); 254 255 _enter("{OBJ%x,%d}", 256 object->fscache.debug_id, atomic_read(&object->usage)); 257 258 cache = container_of(object->fscache.cache, 259 struct cachefiles_cache, cache); 260 261#ifdef CACHEFILES_DEBUG_SLAB 262 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000); 263#endif 264 265 /* delete retired objects */ 266 if (object->fscache.state == FSCACHE_OBJECT_RECYCLING && 267 _object != cache->cache.fsdef 268 ) { 269 _debug("- retire object OBJ%x", object->fscache.debug_id); 270 cachefiles_begin_secure(cache, &saved_cred); 271 cachefiles_delete_object(cache, object); 272 cachefiles_end_secure(cache, saved_cred); 273 } 274 275 /* close the filesystem stuff attached to the object */ 276 if (object->backer != object->dentry) 277 dput(object->backer); 278 object->backer = NULL; 279 280 /* note that the object is now inactive */ 281 if (test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) { 282 write_lock(&cache->active_lock); 283 if (!test_and_clear_bit(CACHEFILES_OBJECT_ACTIVE, 284 &object->flags)) 285 BUG(); 286 rb_erase(&object->active_node, &cache->active_nodes); 287 wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE); 288 write_unlock(&cache->active_lock); 289 } 290 291 dput(object->dentry); 292 object->dentry = NULL; 293 294 _leave(""); 295} 296 297/* 298 * dispose of a reference to an object 299 */ 300static void cachefiles_put_object(struct fscache_object *_object) 301{ 302 struct cachefiles_object *object; 303 struct fscache_cache *cache; 304 305 ASSERT(_object); 306 307 object = container_of(_object, struct cachefiles_object, fscache); 308 309 _enter("{OBJ%x,%d}", 310 object->fscache.debug_id, atomic_read(&object->usage)); 311 312#ifdef CACHEFILES_DEBUG_SLAB 313 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000); 314#endif 315 316 ASSERTIFCMP(object->fscache.parent, 317 object->fscache.parent->n_children, >, 0); 318 319 if (atomic_dec_and_test(&object->usage)) { 320 _debug("- kill object OBJ%x", object->fscache.debug_id); 321 322 ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)); 323 ASSERTCMP(object->fscache.parent, ==, NULL); 324 ASSERTCMP(object->backer, ==, NULL); 325 ASSERTCMP(object->dentry, ==, NULL); 326 ASSERTCMP(object->fscache.n_ops, ==, 0); 327 ASSERTCMP(object->fscache.n_children, ==, 0); 328 329 if (object->lookup_data) { 330 kfree(object->lookup_data->key); 331 kfree(object->lookup_data->auxdata); 332 kfree(object->lookup_data); 333 object->lookup_data = NULL; 334 } 335 336 cache = object->fscache.cache; 337 fscache_object_destroy(&object->fscache); 338 kmem_cache_free(cachefiles_object_jar, object); 339 fscache_object_destroyed(cache); 340 } 341 342 _leave(""); 343} 344 345/* 346 * sync a cache 347 */ 348static void cachefiles_sync_cache(struct fscache_cache *_cache) 349{ 350 struct cachefiles_cache *cache; 351 const struct cred *saved_cred; 352 int ret; 353 354 _enter("%p", _cache); 355 356 cache = container_of(_cache, struct cachefiles_cache, cache); 357 358 /* make sure all pages pinned by operations on behalf of the netfs are 359 * written to disc */ 360 cachefiles_begin_secure(cache, &saved_cred); 361 down_read(&cache->mnt->mnt_sb->s_umount); 362 ret = sync_filesystem(cache->mnt->mnt_sb); 363 up_read(&cache->mnt->mnt_sb->s_umount); 364 cachefiles_end_secure(cache, saved_cred); 365 366 if (ret == -EIO) 367 cachefiles_io_error(cache, 368 "Attempt to sync backing fs superblock" 369 " returned error %d", 370 ret); 371} 372 373/* 374 * notification the attributes on an object have changed 375 * - called with reads/writes excluded by FS-Cache 376 */ 377static int cachefiles_attr_changed(struct fscache_object *_object) 378{ 379 struct cachefiles_object *object; 380 struct cachefiles_cache *cache; 381 const struct cred *saved_cred; 382 struct iattr newattrs; 383 uint64_t ni_size; 384 loff_t oi_size; 385 int ret; 386 387 _object->cookie->def->get_attr(_object->cookie->netfs_data, &ni_size); 388 389 _enter("{OBJ%x},[%llu]", 390 _object->debug_id, (unsigned long long) ni_size); 391 392 object = container_of(_object, struct cachefiles_object, fscache); 393 cache = container_of(object->fscache.cache, 394 struct cachefiles_cache, cache); 395 396 if (ni_size == object->i_size) 397 return 0; 398 399 if (!object->backer) 400 return -ENOBUFS; 401 402 ASSERT(S_ISREG(object->backer->d_inode->i_mode)); 403 404 fscache_set_store_limit(&object->fscache, ni_size); 405 406 oi_size = i_size_read(object->backer->d_inode); 407 if (oi_size == ni_size) 408 return 0; 409 410 cachefiles_begin_secure(cache, &saved_cred); 411 mutex_lock(&object->backer->d_inode->i_mutex); 412 413 /* if there's an extension to a partial page at the end of the backing 414 * file, we need to discard the partial page so that we pick up new 415 * data after it */ 416 if (oi_size & ~PAGE_MASK && ni_size > oi_size) { 417 _debug("discard tail %llx", oi_size); 418 newattrs.ia_valid = ATTR_SIZE; 419 newattrs.ia_size = oi_size & PAGE_MASK; 420 ret = notify_change(object->backer, &newattrs); 421 if (ret < 0) 422 goto truncate_failed; 423 } 424 425 newattrs.ia_valid = ATTR_SIZE; 426 newattrs.ia_size = ni_size; 427 ret = notify_change(object->backer, &newattrs); 428 429truncate_failed: 430 mutex_unlock(&object->backer->d_inode->i_mutex); 431 cachefiles_end_secure(cache, saved_cred); 432 433 if (ret == -EIO) { 434 fscache_set_store_limit(&object->fscache, 0); 435 cachefiles_io_error_obj(object, "Size set failed"); 436 ret = -ENOBUFS; 437 } 438 439 _leave(" = %d", ret); 440 return ret; 441} 442 443/* 444 * dissociate a cache from all the pages it was backing 445 */ 446static void cachefiles_dissociate_pages(struct fscache_cache *cache) 447{ 448 _enter(""); 449} 450 451const struct fscache_cache_ops cachefiles_cache_ops = { 452 .name = "cachefiles", 453 .alloc_object = cachefiles_alloc_object, 454 .lookup_object = cachefiles_lookup_object, 455 .lookup_complete = cachefiles_lookup_complete, 456 .grab_object = cachefiles_grab_object, 457 .update_object = cachefiles_update_object, 458 .drop_object = cachefiles_drop_object, 459 .put_object = cachefiles_put_object, 460 .sync_cache = cachefiles_sync_cache, 461 .attr_changed = cachefiles_attr_changed, 462 .read_or_alloc_page = cachefiles_read_or_alloc_page, 463 .read_or_alloc_pages = cachefiles_read_or_alloc_pages, 464 .allocate_page = cachefiles_allocate_page, 465 .allocate_pages = cachefiles_allocate_pages, 466 .write_page = cachefiles_write_page, 467 .uncache_page = cachefiles_uncache_page, 468 .dissociate_pages = cachefiles_dissociate_pages, 469}; 470