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/namei.h> 13 #include <linux/falloc.h> 14 #include <trace/events/fscache.h> 15 #include "internal.h" 16 17 static atomic_t cachefiles_object_debug_id; 18 19 /* 20 * Allocate a cache object record. 21 */ 22 static 23 struct cachefiles_object *cachefiles_alloc_object(struct fscache_cookie *cookie) 24 { 25 struct fscache_volume *vcookie = cookie->volume; 26 struct cachefiles_volume *volume = vcookie->cache_priv; 27 struct cachefiles_object *object; 28 29 _enter("{%s},%x,", vcookie->key, cookie->debug_id); 30 31 object = kmem_cache_zalloc(cachefiles_object_jar, GFP_KERNEL); 32 if (!object) 33 return NULL; 34 35 refcount_set(&object->ref, 1); 36 37 spin_lock_init(&object->lock); 38 INIT_LIST_HEAD(&object->cache_link); 39 object->volume = volume; 40 object->debug_id = atomic_inc_return(&cachefiles_object_debug_id); 41 object->cookie = fscache_get_cookie(cookie, fscache_cookie_get_attach_object); 42 43 fscache_count_object(vcookie->cache); 44 trace_cachefiles_ref(object->debug_id, cookie->debug_id, 1, 45 cachefiles_obj_new); 46 return object; 47 } 48 49 /* 50 * Note that an object has been seen. 51 */ 52 void cachefiles_see_object(struct cachefiles_object *object, 53 enum cachefiles_obj_ref_trace why) 54 { 55 trace_cachefiles_ref(object->debug_id, object->cookie->debug_id, 56 refcount_read(&object->ref), why); 57 } 58 59 /* 60 * Increment the usage count on an object; 61 */ 62 struct cachefiles_object *cachefiles_grab_object(struct cachefiles_object *object, 63 enum cachefiles_obj_ref_trace why) 64 { 65 int r; 66 67 __refcount_inc(&object->ref, &r); 68 trace_cachefiles_ref(object->debug_id, object->cookie->debug_id, r, why); 69 return object; 70 } 71 72 /* 73 * dispose of a reference to an object 74 */ 75 void cachefiles_put_object(struct cachefiles_object *object, 76 enum cachefiles_obj_ref_trace why) 77 { 78 unsigned int object_debug_id = object->debug_id; 79 unsigned int cookie_debug_id = object->cookie->debug_id; 80 struct fscache_cache *cache; 81 bool done; 82 int r; 83 84 done = __refcount_dec_and_test(&object->ref, &r); 85 trace_cachefiles_ref(object_debug_id, cookie_debug_id, r, why); 86 if (done) { 87 _debug("- kill object OBJ%x", object_debug_id); 88 89 ASSERTCMP(object->file, ==, NULL); 90 91 kfree(object->d_name); 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(&nop_mnt_idmap, 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(&nop_mnt_idmap, 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 struct file *file; 326 327 if (test_bit(FSCACHE_COOKIE_RETIRED, &object->cookie->flags)) { 328 if (!test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags)) { 329 cachefiles_see_object(object, cachefiles_obj_see_clean_delete); 330 _debug("- inval object OBJ%x", object->debug_id); 331 cachefiles_delete_object(object, FSCACHE_OBJECT_WAS_RETIRED); 332 } else { 333 cachefiles_see_object(object, cachefiles_obj_see_clean_drop_tmp); 334 _debug("- inval object OBJ%x tmpfile", object->debug_id); 335 } 336 } else { 337 cachefiles_see_object(object, cachefiles_obj_see_clean_commit); 338 cachefiles_commit_object(object, cache); 339 } 340 341 cachefiles_unmark_inode_in_use(object, object->file); 342 343 spin_lock(&object->lock); 344 file = object->file; 345 object->file = NULL; 346 spin_unlock(&object->lock); 347 348 if (file) 349 fput(file); 350 } 351 352 /* 353 * Withdraw caching for a cookie. 354 */ 355 static void cachefiles_withdraw_cookie(struct fscache_cookie *cookie) 356 { 357 struct cachefiles_object *object = cookie->cache_priv; 358 struct cachefiles_cache *cache = object->volume->cache; 359 const struct cred *saved_cred; 360 361 _enter("o=%x", object->debug_id); 362 cachefiles_see_object(object, cachefiles_obj_see_withdraw_cookie); 363 364 if (!list_empty(&object->cache_link)) { 365 spin_lock(&cache->object_list_lock); 366 cachefiles_see_object(object, cachefiles_obj_see_withdrawal); 367 list_del_init(&object->cache_link); 368 spin_unlock(&cache->object_list_lock); 369 } 370 371 if (object->file) { 372 cachefiles_begin_secure(cache, &saved_cred); 373 cachefiles_clean_up_object(object, cache); 374 cachefiles_end_secure(cache, saved_cred); 375 } 376 377 cookie->cache_priv = NULL; 378 cachefiles_put_object(object, cachefiles_obj_put_detach); 379 } 380 381 /* 382 * Invalidate the storage associated with a cookie. 383 */ 384 static bool cachefiles_invalidate_cookie(struct fscache_cookie *cookie) 385 { 386 struct cachefiles_object *object = cookie->cache_priv; 387 struct file *new_file, *old_file; 388 bool old_tmpfile; 389 390 _enter("o=%x,[%llu]", object->debug_id, object->cookie->object_size); 391 392 old_tmpfile = test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); 393 394 if (!object->file) { 395 fscache_resume_after_invalidation(cookie); 396 _leave(" = t [light]"); 397 return true; 398 } 399 400 new_file = cachefiles_create_tmpfile(object); 401 if (IS_ERR(new_file)) 402 goto failed; 403 404 /* Substitute the VFS target */ 405 _debug("sub"); 406 spin_lock(&object->lock); 407 408 old_file = object->file; 409 object->file = new_file; 410 object->content_info = CACHEFILES_CONTENT_NO_DATA; 411 set_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); 412 set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags); 413 414 spin_unlock(&object->lock); 415 _debug("subbed"); 416 417 /* Allow I/O to take place again */ 418 fscache_resume_after_invalidation(cookie); 419 420 if (old_file) { 421 if (!old_tmpfile) { 422 struct cachefiles_volume *volume = object->volume; 423 struct dentry *fan = volume->fanout[(u8)cookie->key_hash]; 424 struct dentry *obj; 425 426 obj = start_removing_dentry(fan, old_file->f_path.dentry); 427 if (!IS_ERR(obj)) 428 cachefiles_bury_object(volume->cache, object, 429 fan, obj, 430 FSCACHE_OBJECT_INVALIDATED); 431 } 432 fput(old_file); 433 } 434 435 _leave(" = t"); 436 return true; 437 438 failed: 439 _leave(" = f"); 440 return false; 441 } 442 443 const struct fscache_cache_ops cachefiles_cache_ops = { 444 .name = "cachefiles", 445 .acquire_volume = cachefiles_acquire_volume, 446 .free_volume = cachefiles_free_volume, 447 .lookup_cookie = cachefiles_lookup_cookie, 448 .withdraw_cookie = cachefiles_withdraw_cookie, 449 .invalidate_cookie = cachefiles_invalidate_cookie, 450 .begin_operation = cachefiles_begin_operation, 451 .resize_cookie = cachefiles_resize_cookie, 452 .prepare_to_write = cachefiles_prepare_to_write, 453 }; 454