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 <linux/buffer_head.h>
15 #include "internal.h"
16
17 #define list_to_page(head) (list_entry((head)->prev, struct page, lru))
18
19 struct cachefiles_lookup_data {
20 struct cachefiles_xattr *auxdata; /* auxiliary data */
21 char *key; /* key path */
22 };
23
24 static int cachefiles_attr_changed(struct fscache_object *_object);
25
26 /*
27 * allocate an object record for a cookie lookup and prepare the lookup data
28 */
cachefiles_alloc_object(struct fscache_cache * _cache,struct fscache_cookie * cookie)29 static struct fscache_object *cachefiles_alloc_object(
30 struct fscache_cache *_cache,
31 struct fscache_cookie *cookie)
32 {
33 struct cachefiles_lookup_data *lookup_data;
34 struct cachefiles_object *object;
35 struct cachefiles_cache *cache;
36 struct cachefiles_xattr *auxdata;
37 unsigned keylen, auxlen;
38 void *buffer;
39 char *key;
40
41 cache = container_of(_cache, struct cachefiles_cache, cache);
42
43 _enter("{%s},%p,", cache->cache.identifier, cookie);
44
45 lookup_data = kmalloc(sizeof(*lookup_data), GFP_KERNEL);
46 if (!lookup_data)
47 goto nomem_lookup_data;
48
49 /* create a new object record and a temporary leaf image */
50 object = kmem_cache_alloc(cachefiles_object_jar, GFP_KERNEL);
51 if (!object)
52 goto nomem_object;
53
54 ASSERTCMP(object->backer, ==, NULL);
55
56 BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
57 atomic_set(&object->usage, 1);
58
59 fscache_object_init(&object->fscache, cookie, &cache->cache);
60
61 object->type = cookie->def->type;
62
63 /* get hold of the raw key
64 * - stick the length on the front and leave space on the back for the
65 * encoder
66 */
67 buffer = kmalloc((2 + 512) + 3, GFP_KERNEL);
68 if (!buffer)
69 goto nomem_buffer;
70
71 keylen = cookie->def->get_key(cookie->netfs_data, buffer + 2, 512);
72 ASSERTCMP(keylen, <, 512);
73
74 *(uint16_t *)buffer = keylen;
75 ((char *)buffer)[keylen + 2] = 0;
76 ((char *)buffer)[keylen + 3] = 0;
77 ((char *)buffer)[keylen + 4] = 0;
78
79 /* turn the raw key into something that can work with as a filename */
80 key = cachefiles_cook_key(buffer, keylen + 2, object->type);
81 if (!key)
82 goto nomem_key;
83
84 /* get hold of the auxiliary data and prepend the object type */
85 auxdata = buffer;
86 auxlen = 0;
87 if (cookie->def->get_aux) {
88 auxlen = cookie->def->get_aux(cookie->netfs_data,
89 auxdata->data, 511);
90 ASSERTCMP(auxlen, <, 511);
91 }
92
93 auxdata->len = auxlen + 1;
94 auxdata->type = cookie->def->type;
95
96 lookup_data->auxdata = auxdata;
97 lookup_data->key = key;
98 object->lookup_data = lookup_data;
99
100 _leave(" = %p [%p]", &object->fscache, lookup_data);
101 return &object->fscache;
102
103 nomem_key:
104 kfree(buffer);
105 nomem_buffer:
106 BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
107 kmem_cache_free(cachefiles_object_jar, object);
108 fscache_object_destroyed(&cache->cache);
109 nomem_object:
110 kfree(lookup_data);
111 nomem_lookup_data:
112 _leave(" = -ENOMEM");
113 return ERR_PTR(-ENOMEM);
114 }
115
116 /*
117 * attempt to look up the nominated node in this cache
118 * - return -ETIMEDOUT to be scheduled again
119 */
cachefiles_lookup_object(struct fscache_object * _object)120 static int cachefiles_lookup_object(struct fscache_object *_object)
121 {
122 struct cachefiles_lookup_data *lookup_data;
123 struct cachefiles_object *parent, *object;
124 struct cachefiles_cache *cache;
125 const struct cred *saved_cred;
126 int ret;
127
128 _enter("{OBJ%x}", _object->debug_id);
129
130 cache = container_of(_object->cache, struct cachefiles_cache, cache);
131 parent = container_of(_object->parent,
132 struct cachefiles_object, fscache);
133 object = container_of(_object, struct cachefiles_object, fscache);
134 lookup_data = object->lookup_data;
135
136 ASSERTCMP(lookup_data, !=, NULL);
137
138 /* look up the key, creating any missing bits */
139 cachefiles_begin_secure(cache, &saved_cred);
140 ret = cachefiles_walk_to_object(parent, object,
141 lookup_data->key,
142 lookup_data->auxdata);
143 cachefiles_end_secure(cache, saved_cred);
144
145 /* polish off by setting the attributes of non-index files */
146 if (ret == 0 &&
147 object->fscache.cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX)
148 cachefiles_attr_changed(&object->fscache);
149
150 if (ret < 0 && ret != -ETIMEDOUT) {
151 if (ret != -ENOBUFS)
152 printk(KERN_WARNING
153 "CacheFiles: Lookup failed error %d\n", ret);
154 fscache_object_lookup_error(&object->fscache);
155 }
156
157 _leave(" [%d]", ret);
158 return ret;
159 }
160
161 /*
162 * indication of lookup completion
163 */
cachefiles_lookup_complete(struct fscache_object * _object)164 static void cachefiles_lookup_complete(struct fscache_object *_object)
165 {
166 struct cachefiles_object *object;
167
168 object = container_of(_object, struct cachefiles_object, fscache);
169
170 _enter("{OBJ%x,%p}", object->fscache.debug_id, object->lookup_data);
171
172 if (object->lookup_data) {
173 kfree(object->lookup_data->key);
174 kfree(object->lookup_data->auxdata);
175 kfree(object->lookup_data);
176 object->lookup_data = NULL;
177 }
178 }
179
180 /*
181 * increment the usage count on an inode object (may fail if unmounting)
182 */
183 static
cachefiles_grab_object(struct fscache_object * _object)184 struct fscache_object *cachefiles_grab_object(struct fscache_object *_object)
185 {
186 struct cachefiles_object *object =
187 container_of(_object, struct cachefiles_object, fscache);
188
189 _enter("{OBJ%x,%d}", _object->debug_id, atomic_read(&object->usage));
190
191 #ifdef CACHEFILES_DEBUG_SLAB
192 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
193 #endif
194
195 atomic_inc(&object->usage);
196 return &object->fscache;
197 }
198
199 /*
200 * update the auxiliary data for an object object on disk
201 */
cachefiles_update_object(struct fscache_object * _object)202 static void cachefiles_update_object(struct fscache_object *_object)
203 {
204 struct cachefiles_object *object;
205 struct cachefiles_xattr *auxdata;
206 struct cachefiles_cache *cache;
207 struct fscache_cookie *cookie;
208 const struct cred *saved_cred;
209 unsigned auxlen;
210
211 _enter("{OBJ%x}", _object->debug_id);
212
213 object = container_of(_object, struct cachefiles_object, fscache);
214 cache = container_of(object->fscache.cache, struct cachefiles_cache,
215 cache);
216 cookie = object->fscache.cookie;
217
218 if (!cookie->def->get_aux) {
219 _leave(" [no aux]");
220 return;
221 }
222
223 auxdata = kmalloc(2 + 512 + 3, GFP_KERNEL);
224 if (!auxdata) {
225 _leave(" [nomem]");
226 return;
227 }
228
229 auxlen = cookie->def->get_aux(cookie->netfs_data, auxdata->data, 511);
230 ASSERTCMP(auxlen, <, 511);
231
232 auxdata->len = auxlen + 1;
233 auxdata->type = cookie->def->type;
234
235 cachefiles_begin_secure(cache, &saved_cred);
236 cachefiles_update_object_xattr(object, auxdata);
237 cachefiles_end_secure(cache, saved_cred);
238 kfree(auxdata);
239 _leave("");
240 }
241
242 /*
243 * discard the resources pinned by an object and effect retirement if
244 * requested
245 */
cachefiles_drop_object(struct fscache_object * _object)246 static void cachefiles_drop_object(struct fscache_object *_object)
247 {
248 struct cachefiles_object *object;
249 struct cachefiles_cache *cache;
250 const struct cred *saved_cred;
251
252 ASSERT(_object);
253
254 object = container_of(_object, struct cachefiles_object, fscache);
255
256 _enter("{OBJ%x,%d}",
257 object->fscache.debug_id, atomic_read(&object->usage));
258
259 cache = container_of(object->fscache.cache,
260 struct cachefiles_cache, cache);
261
262 #ifdef CACHEFILES_DEBUG_SLAB
263 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
264 #endif
265
266 /* delete retired objects */
267 if (object->fscache.state == FSCACHE_OBJECT_RECYCLING &&
268 _object != cache->cache.fsdef
269 ) {
270 _debug("- retire object OBJ%x", object->fscache.debug_id);
271 cachefiles_begin_secure(cache, &saved_cred);
272 cachefiles_delete_object(cache, object);
273 cachefiles_end_secure(cache, saved_cred);
274 }
275
276 /* close the filesystem stuff attached to the object */
277 if (object->backer != object->dentry)
278 dput(object->backer);
279 object->backer = NULL;
280
281 /* note that the object is now inactive */
282 if (test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
283 write_lock(&cache->active_lock);
284 if (!test_and_clear_bit(CACHEFILES_OBJECT_ACTIVE,
285 &object->flags))
286 BUG();
287 rb_erase(&object->active_node, &cache->active_nodes);
288 wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
289 write_unlock(&cache->active_lock);
290 }
291
292 dput(object->dentry);
293 object->dentry = NULL;
294
295 _leave("");
296 }
297
298 /*
299 * dispose of a reference to an object
300 */
cachefiles_put_object(struct fscache_object * _object)301 static void cachefiles_put_object(struct fscache_object *_object)
302 {
303 struct cachefiles_object *object;
304 struct fscache_cache *cache;
305
306 ASSERT(_object);
307
308 object = container_of(_object, struct cachefiles_object, fscache);
309
310 _enter("{OBJ%x,%d}",
311 object->fscache.debug_id, atomic_read(&object->usage));
312
313 #ifdef CACHEFILES_DEBUG_SLAB
314 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
315 #endif
316
317 ASSERTIFCMP(object->fscache.parent,
318 object->fscache.parent->n_children, >, 0);
319
320 if (atomic_dec_and_test(&object->usage)) {
321 _debug("- kill object OBJ%x", object->fscache.debug_id);
322
323 ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
324 ASSERTCMP(object->fscache.parent, ==, NULL);
325 ASSERTCMP(object->backer, ==, NULL);
326 ASSERTCMP(object->dentry, ==, NULL);
327 ASSERTCMP(object->fscache.n_ops, ==, 0);
328 ASSERTCMP(object->fscache.n_children, ==, 0);
329
330 if (object->lookup_data) {
331 kfree(object->lookup_data->key);
332 kfree(object->lookup_data->auxdata);
333 kfree(object->lookup_data);
334 object->lookup_data = NULL;
335 }
336
337 cache = object->fscache.cache;
338 fscache_object_destroy(&object->fscache);
339 kmem_cache_free(cachefiles_object_jar, object);
340 fscache_object_destroyed(cache);
341 }
342
343 _leave("");
344 }
345
346 /*
347 * sync a cache
348 */
cachefiles_sync_cache(struct fscache_cache * _cache)349 static void cachefiles_sync_cache(struct fscache_cache *_cache)
350 {
351 struct cachefiles_cache *cache;
352 const struct cred *saved_cred;
353 int ret;
354
355 _enter("%p", _cache);
356
357 cache = container_of(_cache, struct cachefiles_cache, cache);
358
359 /* make sure all pages pinned by operations on behalf of the netfs are
360 * written to disc */
361 cachefiles_begin_secure(cache, &saved_cred);
362 down_read(&cache->mnt->mnt_sb->s_umount);
363 ret = sync_filesystem(cache->mnt->mnt_sb);
364 up_read(&cache->mnt->mnt_sb->s_umount);
365 cachefiles_end_secure(cache, saved_cred);
366
367 if (ret == -EIO)
368 cachefiles_io_error(cache,
369 "Attempt to sync backing fs superblock"
370 " returned error %d",
371 ret);
372 }
373
374 /*
375 * notification the attributes on an object have changed
376 * - called with reads/writes excluded by FS-Cache
377 */
cachefiles_attr_changed(struct fscache_object * _object)378 static int cachefiles_attr_changed(struct fscache_object *_object)
379 {
380 struct cachefiles_object *object;
381 struct cachefiles_cache *cache;
382 const struct cred *saved_cred;
383 struct iattr newattrs;
384 uint64_t ni_size;
385 loff_t oi_size;
386 int ret;
387
388 _object->cookie->def->get_attr(_object->cookie->netfs_data, &ni_size);
389
390 _enter("{OBJ%x},[%llu]",
391 _object->debug_id, (unsigned long long) ni_size);
392
393 object = container_of(_object, struct cachefiles_object, fscache);
394 cache = container_of(object->fscache.cache,
395 struct cachefiles_cache, cache);
396
397 if (ni_size == object->i_size)
398 return 0;
399
400 if (!object->backer)
401 return -ENOBUFS;
402
403 ASSERT(S_ISREG(object->backer->d_inode->i_mode));
404
405 fscache_set_store_limit(&object->fscache, ni_size);
406
407 oi_size = i_size_read(object->backer->d_inode);
408 if (oi_size == ni_size)
409 return 0;
410
411 cachefiles_begin_secure(cache, &saved_cred);
412 mutex_lock(&object->backer->d_inode->i_mutex);
413
414 /* if there's an extension to a partial page at the end of the backing
415 * file, we need to discard the partial page so that we pick up new
416 * data after it */
417 if (oi_size & ~PAGE_MASK && ni_size > oi_size) {
418 _debug("discard tail %llx", oi_size);
419 newattrs.ia_valid = ATTR_SIZE;
420 newattrs.ia_size = oi_size & PAGE_MASK;
421 ret = notify_change(object->backer, &newattrs);
422 if (ret < 0)
423 goto truncate_failed;
424 }
425
426 newattrs.ia_valid = ATTR_SIZE;
427 newattrs.ia_size = ni_size;
428 ret = notify_change(object->backer, &newattrs);
429
430 truncate_failed:
431 mutex_unlock(&object->backer->d_inode->i_mutex);
432 cachefiles_end_secure(cache, saved_cred);
433
434 if (ret == -EIO) {
435 fscache_set_store_limit(&object->fscache, 0);
436 cachefiles_io_error_obj(object, "Size set failed");
437 ret = -ENOBUFS;
438 }
439
440 _leave(" = %d", ret);
441 return ret;
442 }
443
444 /*
445 * dissociate a cache from all the pages it was backing
446 */
cachefiles_dissociate_pages(struct fscache_cache * cache)447 static void cachefiles_dissociate_pages(struct fscache_cache *cache)
448 {
449 _enter("");
450 }
451
452 const struct fscache_cache_ops cachefiles_cache_ops = {
453 .name = "cachefiles",
454 .alloc_object = cachefiles_alloc_object,
455 .lookup_object = cachefiles_lookup_object,
456 .lookup_complete = cachefiles_lookup_complete,
457 .grab_object = cachefiles_grab_object,
458 .update_object = cachefiles_update_object,
459 .drop_object = cachefiles_drop_object,
460 .put_object = cachefiles_put_object,
461 .sync_cache = cachefiles_sync_cache,
462 .attr_changed = cachefiles_attr_changed,
463 .read_or_alloc_page = cachefiles_read_or_alloc_page,
464 .read_or_alloc_pages = cachefiles_read_or_alloc_pages,
465 .allocate_page = cachefiles_allocate_page,
466 .allocate_pages = cachefiles_allocate_pages,
467 .write_page = cachefiles_write_page,
468 .uncache_page = cachefiles_uncache_page,
469 .dissociate_pages = cachefiles_dissociate_pages,
470 };
471