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d1065b0a DH |
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 | ||
df98e87f DH |
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 | ||
1f08c925 DH |
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 | ||
7623ed67 DH |
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, | |
b08968f1 | 257 | new_size, dio_size - new_size); |
7623ed67 DH |
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 | ||
1f08c925 DH |
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 | ||
324b954a JX |
365 | cachefiles_ondemand_clean_object(object); |
366 | ||
1f08c925 DH |
367 | if (object->file) { |
368 | cachefiles_begin_secure(cache, &saved_cred); | |
369 | cachefiles_clean_up_object(object, cache); | |
370 | cachefiles_end_secure(cache, saved_cred); | |
371 | } | |
372 | ||
373 | cookie->cache_priv = NULL; | |
374 | cachefiles_put_object(object, cachefiles_obj_put_detach); | |
375 | } | |
376 | ||
377 | /* | |
378 | * Invalidate the storage associated with a cookie. | |
379 | */ | |
380 | static bool cachefiles_invalidate_cookie(struct fscache_cookie *cookie) | |
381 | { | |
382 | struct cachefiles_object *object = cookie->cache_priv; | |
383 | struct file *new_file, *old_file; | |
384 | bool old_tmpfile; | |
385 | ||
386 | _enter("o=%x,[%llu]", object->debug_id, object->cookie->object_size); | |
387 | ||
388 | old_tmpfile = test_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); | |
389 | ||
390 | if (!object->file) { | |
391 | fscache_resume_after_invalidation(cookie); | |
392 | _leave(" = t [light]"); | |
393 | return true; | |
394 | } | |
395 | ||
396 | new_file = cachefiles_create_tmpfile(object); | |
397 | if (IS_ERR(new_file)) | |
398 | goto failed; | |
399 | ||
400 | /* Substitute the VFS target */ | |
401 | _debug("sub"); | |
402 | spin_lock(&object->lock); | |
403 | ||
404 | old_file = object->file; | |
405 | object->file = new_file; | |
406 | object->content_info = CACHEFILES_CONTENT_NO_DATA; | |
407 | set_bit(CACHEFILES_OBJECT_USING_TMPFILE, &object->flags); | |
408 | set_bit(FSCACHE_COOKIE_NEEDS_UPDATE, &object->cookie->flags); | |
409 | ||
410 | spin_unlock(&object->lock); | |
411 | _debug("subbed"); | |
412 | ||
413 | /* Allow I/O to take place again */ | |
414 | fscache_resume_after_invalidation(cookie); | |
415 | ||
416 | if (old_file) { | |
417 | if (!old_tmpfile) { | |
418 | struct cachefiles_volume *volume = object->volume; | |
419 | struct dentry *fan = volume->fanout[(u8)cookie->key_hash]; | |
420 | ||
421 | inode_lock_nested(d_inode(fan), I_MUTEX_PARENT); | |
422 | cachefiles_bury_object(volume->cache, object, fan, | |
423 | old_file->f_path.dentry, | |
424 | FSCACHE_OBJECT_INVALIDATED); | |
425 | } | |
426 | fput(old_file); | |
427 | } | |
428 | ||
429 | _leave(" = t"); | |
430 | return true; | |
431 | ||
432 | failed: | |
433 | _leave(" = f"); | |
434 | return false; | |
435 | } | |
436 | ||
d1065b0a DH |
437 | const struct fscache_cache_ops cachefiles_cache_ops = { |
438 | .name = "cachefiles", | |
fe2140e2 DH |
439 | .acquire_volume = cachefiles_acquire_volume, |
440 | .free_volume = cachefiles_free_volume, | |
1f08c925 DH |
441 | .lookup_cookie = cachefiles_lookup_cookie, |
442 | .withdraw_cookie = cachefiles_withdraw_cookie, | |
443 | .invalidate_cookie = cachefiles_invalidate_cookie, | |
287fd611 | 444 | .begin_operation = cachefiles_begin_operation, |
7623ed67 | 445 | .resize_cookie = cachefiles_resize_cookie, |
1f08c925 | 446 | .prepare_to_write = cachefiles_prepare_to_write, |
d1065b0a | 447 | }; |