projects/linux·blob v3.13 · refs

551 lines · 14.6 KiB

1/* FS-Cache interface to CacheFiles
2 *
3 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
4 * Written by David Howells ([email protected])
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 "internal.h"
15
16struct cachefiles_lookup_data {
17 struct cachefiles_xattr *auxdata; /* auxiliary data */
18 char *key; /* key path */
19};
20
21static int cachefiles_attr_changed(struct fscache_object *_object);
22
23/*
24 * allocate an object record for a cookie lookup and prepare the lookup data
25 */
26static struct fscache_object *cachefiles_alloc_object(
27 struct fscache_cache *_cache,
28 struct fscache_cookie *cookie)
29{
30 struct cachefiles_lookup_data *lookup_data;
31 struct cachefiles_object *object;
32 struct cachefiles_cache *cache;
33 struct cachefiles_xattr *auxdata;
34 unsigned keylen, auxlen;
35 void *buffer;
36 char *key;
37
38 cache = container_of(_cache, struct cachefiles_cache, cache);
39
40 _enter("{%s},%p,", cache->cache.identifier, cookie);
41
42 lookup_data = kmalloc(sizeof(*lookup_data), cachefiles_gfp);
43 if (!lookup_data)
44 goto nomem_lookup_data;
45
46 /* create a new object record and a temporary leaf image */
47 object = kmem_cache_alloc(cachefiles_object_jar, cachefiles_gfp);
48 if (!object)
49 goto nomem_object;
50
51 ASSERTCMP(object->backer, ==, NULL);
52
53 BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
54 atomic_set(&object->usage, 1);
55
56 fscache_object_init(&object->fscache, cookie, &cache->cache);
57
58 object->type = cookie->def->type;
59
60 /* get hold of the raw key
61 * - stick the length on the front and leave space on the back for the
62 * encoder
63 */
64 buffer = kmalloc((2 + 512) + 3, cachefiles_gfp);
65 if (!buffer)
66 goto nomem_buffer;
67
68 keylen = cookie->def->get_key(cookie->netfs_data, buffer + 2, 512);
69 ASSERTCMP(keylen, <, 512);
70
71 *(uint16_t *)buffer = keylen;
72 ((char *)buffer)[keylen + 2] = 0;
73 ((char *)buffer)[keylen + 3] = 0;
74 ((char *)buffer)[keylen + 4] = 0;
75
76 /* turn the raw key into something that can work with as a filename */
77 key = cachefiles_cook_key(buffer, keylen + 2, object->type);
78 if (!key)
79 goto nomem_key;
80
81 /* get hold of the auxiliary data and prepend the object type */
82 auxdata = buffer;
83 auxlen = 0;
84 if (cookie->def->get_aux) {
85 auxlen = cookie->def->get_aux(cookie->netfs_data,
86 auxdata->data, 511);
87 ASSERTCMP(auxlen, <, 511);
88 }
89
90 auxdata->len = auxlen + 1;
91 auxdata->type = cookie->def->type;
92
93 lookup_data->auxdata = auxdata;
94 lookup_data->key = key;
95 object->lookup_data = lookup_data;
96
97 _leave(" = %p [%p]", &object->fscache, lookup_data);
98 return &object->fscache;
99
100nomem_key:
101 kfree(buffer);
102nomem_buffer:
103 BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
104 kmem_cache_free(cachefiles_object_jar, object);
105 fscache_object_destroyed(&cache->cache);
106nomem_object:
107 kfree(lookup_data);
108nomem_lookup_data:
109 _leave(" = -ENOMEM");
110 return ERR_PTR(-ENOMEM);
111}
112
113/*
114 * attempt to look up the nominated node in this cache
115 * - return -ETIMEDOUT to be scheduled again
116 */
117static int cachefiles_lookup_object(struct fscache_object *_object)
118{
119 struct cachefiles_lookup_data *lookup_data;
120 struct cachefiles_object *parent, *object;
121 struct cachefiles_cache *cache;
122 const struct cred *saved_cred;
123 int ret;
124
125 _enter("{OBJ%x}", _object->debug_id);
126
127 cache = container_of(_object->cache, struct cachefiles_cache, cache);
128 parent = container_of(_object->parent,
129 struct cachefiles_object, fscache);
130 object = container_of(_object, struct cachefiles_object, fscache);
131 lookup_data = object->lookup_data;
132
133 ASSERTCMP(lookup_data, !=, NULL);
134
135 /* look up the key, creating any missing bits */
136 cachefiles_begin_secure(cache, &saved_cred);
137 ret = cachefiles_walk_to_object(parent, object,
138 lookup_data->key,
139 lookup_data->auxdata);
140 cachefiles_end_secure(cache, saved_cred);
141
142 /* polish off by setting the attributes of non-index files */
143 if (ret == 0 &&
144 object->fscache.cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX)
145 cachefiles_attr_changed(&object->fscache);
146
147 if (ret < 0 && ret != -ETIMEDOUT) {
148 if (ret != -ENOBUFS)
149 printk(KERN_WARNING
150 "CacheFiles: Lookup failed error %d\n", ret);
151 fscache_object_lookup_error(&object->fscache);
152 }
153
154 _leave(" [%d]", ret);
155 return ret;
156}
157
158/*
159 * indication of lookup completion
160 */
161static void cachefiles_lookup_complete(struct fscache_object *_object)
162{
163 struct cachefiles_object *object;
164
165 object = container_of(_object, struct cachefiles_object, fscache);
166
167 _enter("{OBJ%x,%p}", object->fscache.debug_id, object->lookup_data);
168
169 if (object->lookup_data) {
170 kfree(object->lookup_data->key);
171 kfree(object->lookup_data->auxdata);
172 kfree(object->lookup_data);
173 object->lookup_data = NULL;
174 }
175}
176
177/*
178 * increment the usage count on an inode object (may fail if unmounting)
179 */
180static
181struct fscache_object *cachefiles_grab_object(struct fscache_object *_object)
182{
183 struct cachefiles_object *object =
184 container_of(_object, struct cachefiles_object, fscache);
185
186 _enter("{OBJ%x,%d}", _object->debug_id, atomic_read(&object->usage));
187
188#ifdef CACHEFILES_DEBUG_SLAB
189 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
190#endif
191
192 atomic_inc(&object->usage);
193 return &object->fscache;
194}
195
196/*
197 * update the auxiliary data for an object object on disk
198 */
199static void cachefiles_update_object(struct fscache_object *_object)
200{
201 struct cachefiles_object *object;
202 struct cachefiles_xattr *auxdata;
203 struct cachefiles_cache *cache;
204 struct fscache_cookie *cookie;
205 const struct cred *saved_cred;
206 unsigned auxlen;
207
208 _enter("{OBJ%x}", _object->debug_id);
209
210 object = container_of(_object, struct cachefiles_object, fscache);
211 cache = container_of(object->fscache.cache, struct cachefiles_cache,
212 cache);
213
214 if (!fscache_use_cookie(_object)) {
215 _leave(" [relinq]");
216 return;
217 }
218
219 cookie = object->fscache.cookie;
220
221 if (!cookie->def->get_aux) {
222 fscache_unuse_cookie(_object);
223 _leave(" [no aux]");
224 return;
225 }
226
227 auxdata = kmalloc(2 + 512 + 3, cachefiles_gfp);
228 if (!auxdata) {
229 fscache_unuse_cookie(_object);
230 _leave(" [nomem]");
231 return;
232 }
233
234 auxlen = cookie->def->get_aux(cookie->netfs_data, auxdata->data, 511);
235 fscache_unuse_cookie(_object);
236 ASSERTCMP(auxlen, <, 511);
237
238 auxdata->len = auxlen + 1;
239 auxdata->type = cookie->def->type;
240
241 cachefiles_begin_secure(cache, &saved_cred);
242 cachefiles_update_object_xattr(object, auxdata);
243 cachefiles_end_secure(cache, saved_cred);
244 kfree(auxdata);
245 _leave("");
246}
247
248/*
249 * discard the resources pinned by an object and effect retirement if
250 * requested
251 */
252static void cachefiles_drop_object(struct fscache_object *_object)
253{
254 struct cachefiles_object *object;
255 struct cachefiles_cache *cache;
256 const struct cred *saved_cred;
257
258 ASSERT(_object);
259
260 object = container_of(_object, struct cachefiles_object, fscache);
261
262 _enter("{OBJ%x,%d}",
263 object->fscache.debug_id, atomic_read(&object->usage));
264
265 cache = container_of(object->fscache.cache,
266 struct cachefiles_cache, cache);
267
268#ifdef CACHEFILES_DEBUG_SLAB
269 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
270#endif
271
272 /* delete retired objects */
273 if (test_bit(FSCACHE_OBJECT_RETIRED, &object->fscache.flags) &&
274 _object != cache->cache.fsdef
275 ) {
276 _debug("- retire object OBJ%x", object->fscache.debug_id);
277 cachefiles_begin_secure(cache, &saved_cred);
278 cachefiles_delete_object(cache, object);
279 cachefiles_end_secure(cache, saved_cred);
280 }
281
282 /* close the filesystem stuff attached to the object */
283 if (object->backer != object->dentry)
284 dput(object->backer);
285 object->backer = NULL;
286
287 /* note that the object is now inactive */
288 if (test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
289 write_lock(&cache->active_lock);
290 if (!test_and_clear_bit(CACHEFILES_OBJECT_ACTIVE,
291 &object->flags))
292 BUG();
293 rb_erase(&object->active_node, &cache->active_nodes);
294 wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
295 write_unlock(&cache->active_lock);
296 }
297
298 dput(object->dentry);
299 object->dentry = NULL;
300
301 _leave("");
302}
303
304/*
305 * dispose of a reference to an object
306 */
307static void cachefiles_put_object(struct fscache_object *_object)
308{
309 struct cachefiles_object *object;
310 struct fscache_cache *cache;
311
312 ASSERT(_object);
313
314 object = container_of(_object, struct cachefiles_object, fscache);
315
316 _enter("{OBJ%x,%d}",
317 object->fscache.debug_id, atomic_read(&object->usage));
318
319#ifdef CACHEFILES_DEBUG_SLAB
320 ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
321#endif
322
323 ASSERTIFCMP(object->fscache.parent,
324 object->fscache.parent->n_children, >, 0);
325
326 if (atomic_dec_and_test(&object->usage)) {
327 _debug("- kill object OBJ%x", object->fscache.debug_id);
328
329 ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
330 ASSERTCMP(object->fscache.parent, ==, NULL);
331 ASSERTCMP(object->backer, ==, NULL);
332 ASSERTCMP(object->dentry, ==, NULL);
333 ASSERTCMP(object->fscache.n_ops, ==, 0);
334 ASSERTCMP(object->fscache.n_children, ==, 0);
335
336 if (object->lookup_data) {
337 kfree(object->lookup_data->key);
338 kfree(object->lookup_data->auxdata);
339 kfree(object->lookup_data);
340 object->lookup_data = NULL;
341 }
342
343 cache = object->fscache.cache;
344 fscache_object_destroy(&object->fscache);
345 kmem_cache_free(cachefiles_object_jar, object);
346 fscache_object_destroyed(cache);
347 }
348
349 _leave("");
350}
351
352/*
353 * sync a cache
354 */
355static void cachefiles_sync_cache(struct fscache_cache *_cache)
356{
357 struct cachefiles_cache *cache;
358 const struct cred *saved_cred;
359 int ret;
360
361 _enter("%p", _cache);
362
363 cache = container_of(_cache, struct cachefiles_cache, cache);
364
365 /* make sure all pages pinned by operations on behalf of the netfs are
366 * written to disc */
367 cachefiles_begin_secure(cache, &saved_cred);
368 down_read(&cache->mnt->mnt_sb->s_umount);
369 ret = sync_filesystem(cache->mnt->mnt_sb);
370 up_read(&cache->mnt->mnt_sb->s_umount);
371 cachefiles_end_secure(cache, saved_cred);
372
373 if (ret == -EIO)
374 cachefiles_io_error(cache,
375 "Attempt to sync backing fs superblock"
376 " returned error %d",
377 ret);
378}
379
380/*
381 * check if the backing cache is updated to FS-Cache
382 * - called by FS-Cache when evaluates if need to invalidate the cache
383 */
384static bool cachefiles_check_consistency(struct fscache_operation *op)
385{
386 struct cachefiles_object *object;
387 struct cachefiles_cache *cache;
388 const struct cred *saved_cred;
389 int ret;
390
391 _enter("{OBJ%x}", op->object->debug_id);
392
393 object = container_of(op->object, struct cachefiles_object, fscache);
394 cache = container_of(object->fscache.cache,
395 struct cachefiles_cache, cache);
396
397 cachefiles_begin_secure(cache, &saved_cred);
398 ret = cachefiles_check_auxdata(object);
399 cachefiles_end_secure(cache, saved_cred);
400
401 _leave(" = %d", ret);
402 return ret;
403}
404
405/*
406 * notification the attributes on an object have changed
407 * - called with reads/writes excluded by FS-Cache
408 */
409static int cachefiles_attr_changed(struct fscache_object *_object)
410{
411 struct cachefiles_object *object;
412 struct cachefiles_cache *cache;
413 const struct cred *saved_cred;
414 struct iattr newattrs;
415 uint64_t ni_size;
416 loff_t oi_size;
417 int ret;
418
419 _object->cookie->def->get_attr(_object->cookie->netfs_data, &ni_size);
420
421 _enter("{OBJ%x},[%llu]",
422 _object->debug_id, (unsigned long long) ni_size);
423
424 object = container_of(_object, struct cachefiles_object, fscache);
425 cache = container_of(object->fscache.cache,
426 struct cachefiles_cache, cache);
427
428 if (ni_size == object->i_size)
429 return 0;
430
431 if (!object->backer)
432 return -ENOBUFS;
433
434 ASSERT(S_ISREG(object->backer->d_inode->i_mode));
435
436 fscache_set_store_limit(&object->fscache, ni_size);
437
438 oi_size = i_size_read(object->backer->d_inode);
439 if (oi_size == ni_size)
440 return 0;
441
442 cachefiles_begin_secure(cache, &saved_cred);
443 mutex_lock(&object->backer->d_inode->i_mutex);
444
445 /* if there's an extension to a partial page at the end of the backing
446 * file, we need to discard the partial page so that we pick up new
447 * data after it */
448 if (oi_size & ~PAGE_MASK && ni_size > oi_size) {
449 _debug("discard tail %llx", oi_size);
450 newattrs.ia_valid = ATTR_SIZE;
451 newattrs.ia_size = oi_size & PAGE_MASK;
452 ret = notify_change(object->backer, &newattrs, NULL);
453 if (ret < 0)
454 goto truncate_failed;
455 }
456
457 newattrs.ia_valid = ATTR_SIZE;
458 newattrs.ia_size = ni_size;
459 ret = notify_change(object->backer, &newattrs, NULL);
460
461truncate_failed:
462 mutex_unlock(&object->backer->d_inode->i_mutex);
463 cachefiles_end_secure(cache, saved_cred);
464
465 if (ret == -EIO) {
466 fscache_set_store_limit(&object->fscache, 0);
467 cachefiles_io_error_obj(object, "Size set failed");
468 ret = -ENOBUFS;
469 }
470
471 _leave(" = %d", ret);
472 return ret;
473}
474
475/*
476 * Invalidate an object
477 */
478static void cachefiles_invalidate_object(struct fscache_operation *op)
479{
480 struct cachefiles_object *object;
481 struct cachefiles_cache *cache;
482 const struct cred *saved_cred;
483 struct path path;
484 uint64_t ni_size;
485 int ret;
486
487 object = container_of(op->object, struct cachefiles_object, fscache);
488 cache = container_of(object->fscache.cache,
489 struct cachefiles_cache, cache);
490
491 op->object->cookie->def->get_attr(op->object->cookie->netfs_data,
492 &ni_size);
493
494 _enter("{OBJ%x},[%llu]",
495 op->object->debug_id, (unsigned long long)ni_size);
496
497 if (object->backer) {
498 ASSERT(S_ISREG(object->backer->d_inode->i_mode));
499
500 fscache_set_store_limit(&object->fscache, ni_size);
501
502 path.dentry = object->backer;
503 path.mnt = cache->mnt;
504
505 cachefiles_begin_secure(cache, &saved_cred);
506 ret = vfs_truncate(&path, 0);
507 if (ret == 0)
508 ret = vfs_truncate(&path, ni_size);
509 cachefiles_end_secure(cache, saved_cred);
510
511 if (ret != 0) {
512 fscache_set_store_limit(&object->fscache, 0);
513 if (ret == -EIO)
514 cachefiles_io_error_obj(object,
515 "Invalidate failed");
516 }
517 }
518
519 fscache_op_complete(op, true);
520 _leave("");
521}
522
523/*
524 * dissociate a cache from all the pages it was backing
525 */
526static void cachefiles_dissociate_pages(struct fscache_cache *cache)
527{
528 _enter("");
529}
530
531const struct fscache_cache_ops cachefiles_cache_ops = {
532 .name = "cachefiles",
533 .alloc_object = cachefiles_alloc_object,
534 .lookup_object = cachefiles_lookup_object,
535 .lookup_complete = cachefiles_lookup_complete,
536 .grab_object = cachefiles_grab_object,
537 .update_object = cachefiles_update_object,
538 .invalidate_object = cachefiles_invalidate_object,
539 .drop_object = cachefiles_drop_object,
540 .put_object = cachefiles_put_object,
541 .sync_cache = cachefiles_sync_cache,
542 .attr_changed = cachefiles_attr_changed,
543 .read_or_alloc_page = cachefiles_read_or_alloc_page,
544 .read_or_alloc_pages = cachefiles_read_or_alloc_pages,
545 .allocate_page = cachefiles_allocate_page,
546 .allocate_pages = cachefiles_allocate_pages,
547 .write_page = cachefiles_write_page,
548 .uncache_page = cachefiles_uncache_page,
549 .dissociate_pages = cachefiles_dissociate_pages,
550 .check_consistency = cachefiles_check_consistency,
551};