1 // SPDX-License-Identifier: GPL-2.0-or-later 2 /* FS-Cache interface to CacheFiles 3 * 4 * Copyright (C) 2021 Red Hat, Inc. All Rights Reserved. 5 * Written by David Howells (dhowells@redhat.com) 6 */ 7 8 #include <linux/slab.h> 9 #include <linux/mount.h> 10 #include <linux/xattr.h> 11 #include <linux/file.h> 12 #include <linux/falloc.h> 13 #include <trace/events/fscache.h> 14 #include "internal.h" 15 16 static atomic_t cachefiles_object_debug_id; 17 18 /* 19 * Allocate a cache object record. 20 */ 21 static 22 struct cachefiles_object *cachefiles_alloc_object(struct fscache_cookie *cookie) 23 { 24 struct fscache_volume *vcookie = cookie->volume; 25 struct cachefiles_volume *volume = vcookie->cache_priv; 26 struct cachefiles_object *object; 27 28 _enter("{%s},%x,", vcookie->key, cookie->debug_id); 29 30 object = kmem_cache_zalloc(cachefiles_object_jar, GFP_KERNEL); 31 if (!object) 32 return NULL; 33 34 refcount_set(&object->ref, 1); 35 36 spin_lock_init(&object->lock); 37 INIT_LIST_HEAD(&object->cache_link); 38 object->volume = volume; 39 object->debug_id = atomic_inc_return(&cachefiles_object_debug_id); 40 object->cookie = fscache_get_cookie(cookie, fscache_cookie_get_attach_object); 41 42 fscache_count_object(vcookie->cache); 43 trace_cachefiles_ref(object->debug_id, cookie->debug_id, 1, 44 cachefiles_obj_new); 45 return object; 46 } 47 48 /* 49 * Note that an object has been seen. 50 */ 51 void cachefiles_see_object(struct cachefiles_object *object, 52 enum cachefiles_obj_ref_trace why) 53 { 54 trace_cachefiles_ref(object->debug_id, object->cookie->debug_id, 55 refcount_read(&object->ref), why); 56 } 57 58 /* 59 * Increment the usage count on an object; 60 */ 61 struct cachefiles_object *cachefiles_grab_object(struct cachefiles_object *object, 62 enum cachefiles_obj_ref_trace why) 63 { 64 int r; 65 66 __refcount_inc(&object->ref, &r); 67 trace_cachefiles_ref(object->debug_id, object->cookie->debug_id, r, why); 68 return object; 69 } 70 71 /* 72 * dispose of a reference to an object 73 */ 74 void cachefiles_put_object(struct cachefiles_object *object, 75 enum cachefiles_obj_ref_trace why) 76 { 77 unsigned int object_debug_id = object->debug_id; 78 unsigned int cookie_debug_id = object->cookie->debug_id; 79 struct fscache_cache *cache; 80 bool done; 81 int r; 82 83 done = __refcount_dec_and_test(&object->ref, &r); 84 trace_cachefiles_ref(object_debug_id, cookie_debug_id, r, why); 85 if (done) { 86 _debug("- kill object OBJ%x", object_debug_id); 87 88 ASSERTCMP(object->file, ==, NULL); 89 90 kfree(object->d_name); 91 92 cache = object->volume->cache->cache; 93 fscache_put_cookie(object->cookie, fscache_cookie_put_object); 94 object->cookie = NULL; 95 kmem_cache_free(cachefiles_object_jar, object); 96 fscache_uncount_object(cache); 97 } 98 99 _leave(""); 100 } 101 102 /* 103 * Adjust the size of a cache file if necessary to match the DIO size. We keep 104 * the EOF marker a multiple of DIO blocks so that we don't fall back to doing 105 * non-DIO for a partial block straddling the EOF, but we also have to be 106 * careful of someone expanding the file and accidentally accreting the 107 * padding. 108 */ 109 static int cachefiles_adjust_size(struct cachefiles_object *object) 110 { 111 struct iattr newattrs; 112 struct file *file = object->file; 113 uint64_t ni_size; 114 loff_t oi_size; 115 int ret; 116 117 ni_size = object->cookie->object_size; 118 ni_size = round_up(ni_size, CACHEFILES_DIO_BLOCK_SIZE); 119 120 _enter("{OBJ%x},[%llu]", 121 object->debug_id, (unsigned long long) ni_size); 122 123 if (!file) 124 return -ENOBUFS; 125 126 oi_size = i_size_read(file_inode(file)); 127 if (oi_size == ni_size) 128 return 0; 129 130 inode_lock(file_inode(file)); 131 132 /* if there's an extension to a partial page at the end of the backing 133 * file, we need to discard the partial page so that we pick up new 134 * data after it */ 135 if (oi_size & ~PAGE_MASK && ni_size > oi_size) { 136 _debug("discard tail %llx", oi_size); 137 newattrs.ia_valid = ATTR_SIZE; 138 newattrs.ia_size = oi_size & PAGE_MASK; 139 ret = cachefiles_inject_remove_error(); 140 if (ret == 0) 141 ret = notify_change(&init_user_ns, file->f_path.dentry, 142 &newattrs, NULL); 143 if (ret < 0) 144 goto truncate_failed; 145 } 146 147 newattrs.ia_valid = ATTR_SIZE; 148 newattrs.ia_size = ni_size; 149 ret = cachefiles_inject_write_error(); 150 if (ret == 0) 151 ret = notify_change(&init_user_ns, file->f_path.dentry, 152 &newattrs, NULL); 153 154 truncate_failed: 155 inode_unlock(file_inode(file)); 156 157 if (ret < 0) 158 trace_cachefiles_io_error(NULL, file_inode(file), ret, 159 cachefiles_trace_notify_change_error); 160 if (ret == -EIO) { 161 cachefiles_io_error_obj(object, "Size set failed"); 162 ret = -ENOBUFS; 163 } 164 165 _leave(" = %d", ret); 166 return ret; 167 } 168 169 /* 170 * Attempt to look up the nominated node in this cache 171 */ 172 static bool cachefiles_lookup_cookie(struct fscache_cookie *cookie) 173 { 174 struct cachefiles_object *object; 175 struct cachefiles_cache *cache = cookie->volume->cache->cache_priv; 176 const struct cred *saved_cred; 177 bool success; 178 179 object = cachefiles_alloc_object(cookie); 180 if (!object) 181 goto fail; 182 183 _enter("{OBJ%x}", object->debug_id); 184 185 if (!cachefiles_cook_key(object)) 186 goto fail_put; 187 188 cookie->cache_priv = object; 189 190 cachefiles_begin_secure(cache, &saved_cred); 191 192 success = cachefiles_look_up_object(object); 193 if (!success) 194 goto fail_withdraw; 195 196 cachefiles_see_object(object, cachefiles_obj_see_lookup_cookie); 197 198 spin_lock(&cache->object_list_lock); 199 list_add(&object->cache_link, &cache->object_list); 200 spin_unlock(&cache->object_list_lock); 201 cachefiles_adjust_size(object); 202 203 cachefiles_end_secure(cache, saved_cred); 204 _leave(" = t"); 205 return true; 206 207 fail_withdraw: 208 cachefiles_end_secure(cache, saved_cred); 209 cachefiles_see_object(object, cachefiles_obj_see_lookup_failed); 210 fscache_caching_failed(cookie); 211 _debug("failed c=%08x o=%08x", cookie->debug_id, object->debug_id); 212 /* The caller holds an access count on the cookie, so we need them to 213 * drop it before we can withdraw the object. 214 */ 215 return false; 216 217 fail_put: 218 cachefiles_put_object(object, cachefiles_obj_put_alloc_fail); 219 fail: 220 return false; 221 } 222 223 /* 224 * Shorten the backing object to discard any dirty data and free up 225 * any unused granules. 226 */ 227 static bool cachefiles_shorten_object(struct cachefiles_object *object, 228 struct file *file, loff_t new_size) 229 { 230 struct cachefiles_cache *cache = object->volume->cache; 231 struct inode *inode = file_inode(file); 232 loff_t i_size, dio_size; 233 int ret; 234 235 dio_size = round_up(new_size, CACHEFILES_DIO_BLOCK_SIZE); 236 i_size = i_size_read(inode); 237 238 trace_cachefiles_trunc(object, inode, i_size, dio_size, 239 cachefiles_trunc_shrink); 240 ret = cachefiles_inject_remove_error(); 241 if (ret == 0) 242 ret = vfs_truncate(&file->f_path, dio_size); 243 if (ret < 0) { 244 trace_cachefiles_io_error(object, file_inode(file), ret, 245 cachefiles_trace_trunc_error); 246 cachefiles_io_error_obj(object, "Trunc-to-size failed %d", ret); 247 cachefiles_remove_object_xattr(cache, object, file->f_path.dentry); 248 return false; 249 } 250 251 if (new_size < dio_size) { 252 trace_cachefiles_trunc(object, inode, dio_size, new_size, 253 cachefiles_trunc_dio_adjust); 254 ret = cachefiles_inject_write_error(); 255 if (ret == 0) 256 ret = vfs_fallocate(file, FALLOC_FL_ZERO_RANGE, 257 new_size, dio_size - new_size); 258 if (ret < 0) { 259 trace_cachefiles_io_error(object, file_inode(file), ret, 260 cachefiles_trace_fallocate_error); 261 cachefiles_io_error_obj(object, "Trunc-to-dio-size failed %d", ret); 262 cachefiles_remove_object_xattr(cache, object, file->f_path.dentry); 263 return false; 264 } 265 } 266 267 return true; 268 } 269 270 /* 271 * Resize the backing object. 272 */ 273 static void cachefiles_resize_cookie(struct netfs_cache_resources *cres, 274 loff_t new_size) 275 { 276 struct cachefiles_object *object = cachefiles_cres_object(cres); 277 struct cachefiles_cache *cache = object->volume->cache; 278 struct fscache_cookie *cookie = object->cookie; 279 const struct cred *saved_cred; 280 struct file *file = cachefiles_cres_file(cres); 281 loff_t old_size = cookie->object_size; 282 283 _enter("%llu->%llu", old_size, new_size); 284 285 if (new_size < old_size) { 286 cachefiles_begin_secure(cache, &saved_cred); 287 cachefiles_shorten_object(object, file, new_size); 288 cachefiles_end_secure(cache, saved_cred); 289 object->cookie->object_size = new_size; 290 return; 291 } 292 293 /* The file is being expanded. We don't need to do anything 294 * particularly. cookie->initial_size doesn't change and so the point 295 * at which we have to download before doesn't change. 296 */ 297 cookie->object_size = new_size; 298 } 299 300 /* 301 * Commit changes to the object as we drop it. 302 */ 303 static void cachefiles_commit_object(struct cachefiles_object *object, 304 struct cachefiles_cache *cache) 305 { 306 bool update = false; 307 308 if (test_and_clear_bit(FSCACHE_COOKIE_LOCAL_WRITE, &object->cookie->flags)) 309 update = true; 310 if (test_and_clear_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags)) 311 update = true; 312 if (update) 313 cachefiles_set_object_xattr(object); 314 315 if (test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) 316 cachefiles_commit_tmpfile(cache, object); 317 } 318 319 /* 320 * Finalise and object and close the VFS structs that we have. 321 */ 322 static void cachefiles_clean_up_object(struct cachefiles_object *object, 323 struct cachefiles_cache *cache) 324 { 325 if (test_bit(FSCACHE_COOKIE_RETIRED, &object->cookie->flags)) { 326 if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) { 327 cachefiles_see_object(object, cachefiles_obj_see_clean_delete); 328 _debug("- inval object OBJ%x", object->debug_id); 329 cachefiles_delete_object(object, FSCACHE_OBJECT_WAS_RETIRED); 330 } else { 331 cachefiles_see_object(object, cachefiles_obj_see_clean_drop_tmp); 332 _debug("- inval object OBJ%x tmpfile", object->debug_id); 333 } 334 } else { 335 cachefiles_see_object(object, cachefiles_obj_see_clean_commit); 336 cachefiles_commit_object(object, cache); 337 } 338 339 cachefiles_unmark_inode_in_use(object, object->file); 340 if (object->file) { 341 fput(object->file); 342 object->file = NULL; 343 } 344 } 345 346 /* 347 * Withdraw caching for a cookie. 348 */ 349 static void cachefiles_withdraw_cookie(struct fscache_cookie *cookie) 350 { 351 struct cachefiles_object *object = cookie->cache_priv; 352 struct cachefiles_cache *cache = object->volume->cache; 353 const struct cred *saved_cred; 354 355 _enter("o=%x", object->debug_id); 356 cachefiles_see_object(object, cachefiles_obj_see_withdraw_cookie); 357 358 if (!list_empty(&object->cache_link)) { 359 spin_lock(&cache->object_list_lock); 360 cachefiles_see_object(object, cachefiles_obj_see_withdrawal); 361 list_del_init(&object->cache_link); 362 spin_unlock(&cache->object_list_lock); 363 } 364 365 if (object->file) { 366 cachefiles_begin_secure(cache, &saved_cred); 367 cachefiles_clean_up_object(object, cache); 368 cachefiles_end_secure(cache, saved_cred); 369 } 370 371 cookie->cache_priv = NULL; 372 cachefiles_put_object(object, cachefiles_obj_put_detach); 373 } 374 375 /* 376 * Invalidate the storage associated with a cookie. 377 */ 378 static bool cachefiles_invalidate_cookie(struct fscache_cookie *cookie) 379 { 380 struct cachefiles_object *object = cookie->cache_priv; 381 struct file *new_file, *old_file; 382 bool old_tmpfile; 383 384 _enter("o=%x,[%llu]", object->debug_id, object->cookie->object_size); 385 386 old_tmpfile = test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); 387 388 if (!object->file) { 389 fscache_resume_after_invalidation(cookie); 390 _leave(" = t [light]"); 391 return true; 392 } 393 394 new_file = cachefiles_create_tmpfile(object); 395 if (IS_ERR(new_file)) 396 goto failed; 397 398 /* Substitute the VFS target */ 399 _debug("sub"); 400 spin_lock(&object->lock); 401 402 old_file = object->file; 403 object->file = new_file; 404 object->content_info = CACHEFILES_CONTENT_NO_DATA; 405 set_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); 406 set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags); 407 408 spin_unlock(&object->lock); 409 _debug("subbed"); 410 411 /* Allow I/O to take place again */ 412 fscache_resume_after_invalidation(cookie); 413 414 if (old_file) { 415 if (!old_tmpfile) { 416 struct cachefiles_volume *volume = object->volume; 417 struct dentry *fan = volume->fanout[(u8)cookie->key_hash]; 418 419 inode_lock_nested(d_inode(fan), I_MUTEX_PARENT); 420 cachefiles_bury_object(volume->cache, object, fan, 421 old_file->f_path.dentry, 422 FSCACHE_OBJECT_INVALIDATED); 423 } 424 fput(old_file); 425 } 426 427 _leave(" = t"); 428 return true; 429 430 failed: 431 _leave(" = f"); 432 return false; 433 } 434 435 const struct fscache_cache_ops cachefiles_cache_ops = { 436 .name = "cachefiles", 437 .acquire_volume = cachefiles_acquire_volume, 438 .free_volume = cachefiles_free_volume, 439 .lookup_cookie = cachefiles_lookup_cookie, 440 .withdraw_cookie = cachefiles_withdraw_cookie, 441 .invalidate_cookie = cachefiles_invalidate_cookie, 442 .begin_operation = cachefiles_begin_operation, 443 .resize_cookie = cachefiles_resize_cookie, 444 .prepare_to_write = cachefiles_prepare_to_write, 445 }; 446