blob: 1e962348d1114267f85895c7b60870754692ac76 [file] [log] [blame]
David Howells9ae326a2009-04-03 16:42:41 +01001/* 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/mount.h>
13#include <linux/buffer_head.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 */
118static void cachefiles_lookup_object(struct fscache_object *_object)
119{
120 struct cachefiles_lookup_data *lookup_data;
121 struct cachefiles_object *parent, *object;
122 struct cachefiles_cache *cache;
123 const struct cred *saved_cred;
124 int ret;
125
126 _enter("{OBJ%x}", _object->debug_id);
127
128 cache = container_of(_object->cache, struct cachefiles_cache, cache);
129 parent = container_of(_object->parent,
130 struct cachefiles_object, fscache);
131 object = container_of(_object, struct cachefiles_object, fscache);
132 lookup_data = object->lookup_data;
133
134 ASSERTCMP(lookup_data, !=, NULL);
135
136 /* look up the key, creating any missing bits */
137 cachefiles_begin_secure(cache, &saved_cred);
138 ret = cachefiles_walk_to_object(parent, object,
139 lookup_data->key,
140 lookup_data->auxdata);
141 cachefiles_end_secure(cache, saved_cred);
142
143 /* polish off by setting the attributes of non-index files */
144 if (ret == 0 &&
145 object->fscache.cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX)
146 cachefiles_attr_changed(&object->fscache);
147
148 if (ret < 0) {
149 printk(KERN_WARNING "CacheFiles: Lookup failed error %d\n",
150 ret);
151 fscache_object_lookup_error(&object->fscache);
152 }
153
154 _leave(" [%d]", ret);
155}
156
157/*
158 * indication of lookup completion
159 */
160static void cachefiles_lookup_complete(struct fscache_object *_object)
161{
162 struct cachefiles_object *object;
163
164 object = container_of(_object, struct cachefiles_object, fscache);
165
166 _enter("{OBJ%x,%p}", object->fscache.debug_id, object->lookup_data);
167
168 if (object->lookup_data) {
169 kfree(object->lookup_data->key);
170 kfree(object->lookup_data->auxdata);
171 kfree(object->lookup_data);
172 object->lookup_data = NULL;
173 }
174}
175
176/*
177 * increment the usage count on an inode object (may fail if unmounting)
178 */
179static
180struct fscache_object *cachefiles_grab_object(struct fscache_object *_object)
181{
182 struct cachefiles_object *object =
183 container_of(_object, struct cachefiles_object, fscache);
184
185 _enter("{OBJ%x,%d}", _object->debug_id, atomic_read(&object->usage));
186
187#ifdef CACHEFILES_DEBUG_SLAB
188 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
189#endif
190
191 atomic_inc(&object->usage);
192 return &object->fscache;
193}
194
195/*
196 * update the auxilliary data for an object object on disk
197 */
198static void cachefiles_update_object(struct fscache_object *_object)
199{
200 struct cachefiles_object *object;
201 struct cachefiles_xattr *auxdata;
202 struct cachefiles_cache *cache;
203 struct fscache_cookie *cookie;
204 const struct cred *saved_cred;
205 unsigned auxlen;
206
207 _enter("{OBJ%x}", _object->debug_id);
208
209 object = container_of(_object, struct cachefiles_object, fscache);
210 cache = container_of(object->fscache.cache, struct cachefiles_cache,
211 cache);
212 cookie = object->fscache.cookie;
213
214 if (!cookie->def->get_aux) {
215 _leave(" [no aux]");
216 return;
217 }
218
219 auxdata = kmalloc(2 + 512 + 3, GFP_KERNEL);
220 if (!auxdata) {
221 _leave(" [nomem]");
222 return;
223 }
224
225 auxlen = cookie->def->get_aux(cookie->netfs_data, auxdata->data, 511);
226 ASSERTCMP(auxlen, <, 511);
227
228 auxdata->len = auxlen + 1;
229 auxdata->type = cookie->def->type;
230
231 cachefiles_begin_secure(cache, &saved_cred);
232 cachefiles_update_object_xattr(object, auxdata);
233 cachefiles_end_secure(cache, saved_cred);
234 kfree(auxdata);
235 _leave("");
236}
237
238/*
239 * discard the resources pinned by an object and effect retirement if
240 * requested
241 */
242static void cachefiles_drop_object(struct fscache_object *_object)
243{
244 struct cachefiles_object *object;
245 struct cachefiles_cache *cache;
246 const struct cred *saved_cred;
247
248 ASSERT(_object);
249
250 object = container_of(_object, struct cachefiles_object, fscache);
251
252 _enter("{OBJ%x,%d}",
253 object->fscache.debug_id, atomic_read(&object->usage));
254
255 cache = container_of(object->fscache.cache,
256 struct cachefiles_cache, cache);
257
258#ifdef CACHEFILES_DEBUG_SLAB
259 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
260#endif
261
262 /* delete retired objects */
263 if (object->fscache.state == FSCACHE_OBJECT_RECYCLING &&
264 _object != cache->cache.fsdef
265 ) {
266 _debug("- retire object OBJ%x", object->fscache.debug_id);
267 cachefiles_begin_secure(cache, &saved_cred);
268 cachefiles_delete_object(cache, object);
269 cachefiles_end_secure(cache, saved_cred);
270 }
271
272 /* close the filesystem stuff attached to the object */
273 if (object->backer != object->dentry)
274 dput(object->backer);
275 object->backer = NULL;
276
277 /* note that the object is now inactive */
278 if (test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
279 write_lock(&cache->active_lock);
280 if (!test_and_clear_bit(CACHEFILES_OBJECT_ACTIVE,
281 &object->flags))
282 BUG();
283 rb_erase(&object->active_node, &cache->active_nodes);
284 wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
285 write_unlock(&cache->active_lock);
286 }
287
288 dput(object->dentry);
289 object->dentry = NULL;
290
291 _leave("");
292}
293
294/*
295 * dispose of a reference to an object
296 */
297static void cachefiles_put_object(struct fscache_object *_object)
298{
299 struct cachefiles_object *object;
300 struct fscache_cache *cache;
301
302 ASSERT(_object);
303
304 object = container_of(_object, struct cachefiles_object, fscache);
305
306 _enter("{OBJ%x,%d}",
307 object->fscache.debug_id, atomic_read(&object->usage));
308
309#ifdef CACHEFILES_DEBUG_SLAB
310 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
311#endif
312
313 ASSERTIFCMP(object->fscache.parent,
314 object->fscache.parent->n_children, >, 0);
315
316 if (atomic_dec_and_test(&object->usage)) {
317 _debug("- kill object OBJ%x", object->fscache.debug_id);
318
319 ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
320 ASSERTCMP(object->fscache.parent, ==, NULL);
321 ASSERTCMP(object->backer, ==, NULL);
322 ASSERTCMP(object->dentry, ==, NULL);
323 ASSERTCMP(object->fscache.n_ops, ==, 0);
324 ASSERTCMP(object->fscache.n_children, ==, 0);
325
326 if (object->lookup_data) {
327 kfree(object->lookup_data->key);
328 kfree(object->lookup_data->auxdata);
329 kfree(object->lookup_data);
330 object->lookup_data = NULL;
331 }
332
333 cache = object->fscache.cache;
334 kmem_cache_free(cachefiles_object_jar, object);
335 fscache_object_destroyed(cache);
336 }
337
338 _leave("");
339}
340
341/*
342 * sync a cache
343 */
344static void cachefiles_sync_cache(struct fscache_cache *_cache)
345{
346 struct cachefiles_cache *cache;
347 const struct cred *saved_cred;
348 int ret;
349
350 _enter("%p", _cache);
351
352 cache = container_of(_cache, struct cachefiles_cache, cache);
353
354 /* make sure all pages pinned by operations on behalf of the netfs are
355 * written to disc */
356 cachefiles_begin_secure(cache, &saved_cred);
357 ret = fsync_super(cache->mnt->mnt_sb);
358 cachefiles_end_secure(cache, saved_cred);
359
360 if (ret == -EIO)
361 cachefiles_io_error(cache,
362 "Attempt to sync backing fs superblock"
363 " returned error %d",
364 ret);
365}
366
367/*
368 * notification the attributes on an object have changed
369 * - called with reads/writes excluded by FS-Cache
370 */
371static int cachefiles_attr_changed(struct fscache_object *_object)
372{
373 struct cachefiles_object *object;
374 struct cachefiles_cache *cache;
375 const struct cred *saved_cred;
376 struct iattr newattrs;
377 uint64_t ni_size;
378 loff_t oi_size;
379 int ret;
380
381 _object->cookie->def->get_attr(_object->cookie->netfs_data, &ni_size);
382
383 _enter("{OBJ%x},[%llu]",
384 _object->debug_id, (unsigned long long) ni_size);
385
386 object = container_of(_object, struct cachefiles_object, fscache);
387 cache = container_of(object->fscache.cache,
388 struct cachefiles_cache, cache);
389
390 if (ni_size == object->i_size)
391 return 0;
392
393 if (!object->backer)
394 return -ENOBUFS;
395
396 ASSERT(S_ISREG(object->backer->d_inode->i_mode));
397
398 fscache_set_store_limit(&object->fscache, ni_size);
399
400 oi_size = i_size_read(object->backer->d_inode);
401 if (oi_size == ni_size)
402 return 0;
403
404 newattrs.ia_size = ni_size;
405 newattrs.ia_valid = ATTR_SIZE;
406
407 cachefiles_begin_secure(cache, &saved_cred);
408 mutex_lock(&object->backer->d_inode->i_mutex);
409 ret = notify_change(object->backer, &newattrs);
410 mutex_unlock(&object->backer->d_inode->i_mutex);
411 cachefiles_end_secure(cache, saved_cred);
412
413 if (ret == -EIO) {
414 fscache_set_store_limit(&object->fscache, 0);
415 cachefiles_io_error_obj(object, "Size set failed");
416 ret = -ENOBUFS;
417 }
418
419 _leave(" = %d", ret);
420 return ret;
421}
422
423/*
424 * dissociate a cache from all the pages it was backing
425 */
426static void cachefiles_dissociate_pages(struct fscache_cache *cache)
427{
428 _enter("");
429}
430
431const struct fscache_cache_ops cachefiles_cache_ops = {
432 .name = "cachefiles",
433 .alloc_object = cachefiles_alloc_object,
434 .lookup_object = cachefiles_lookup_object,
435 .lookup_complete = cachefiles_lookup_complete,
436 .grab_object = cachefiles_grab_object,
437 .update_object = cachefiles_update_object,
438 .drop_object = cachefiles_drop_object,
439 .put_object = cachefiles_put_object,
440 .sync_cache = cachefiles_sync_cache,
441 .attr_changed = cachefiles_attr_changed,
442 .read_or_alloc_page = cachefiles_read_or_alloc_page,
443 .read_or_alloc_pages = cachefiles_read_or_alloc_pages,
444 .allocate_page = cachefiles_allocate_page,
445 .allocate_pages = cachefiles_allocate_pages,
446 .write_page = cachefiles_write_page,
447 .uncache_page = cachefiles_uncache_page,
448 .dissociate_pages = cachefiles_dissociate_pages,
449};