aboutsummaryrefslogtreecommitdiff
path: root/fs/cachefiles/interface.c
blob: 746ce532e130ac3f49b7a31096b95fda6ef1d18e (plain)
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
271
272
273
274
275
276
277
278
279
280
281
282
283
284
285
286
287
288
289
290
291
292
293
294
295
296
297
298
299
300
301
302
303
304
305
306
307
308
309
310
311
312
313
314
315
316
317
318
319
320
321
322
323
324
325
326
327
328
329
330
331
332
333
334
335
336
337
338
339
340
341
342
343
344
345
346
347
348
349
350
351
352
353
354
355
356
357
358
359
360
361
362
363
364
365
366
367
368
369
370
371
372
373
374
375
376
377
378
379
380
381
382
383
384
385
386
387
388
389
390
391
392
393
394
395
396
397
398
399
400
401
402
403
404
405
406
407
408
409
410
411
412
413
414
415
416
417
418
419
420
421
422
423
424
425
426
427
428
429
430
431
432
433
434
435
436
437
438
439
440
441
442
443
444
445
446
447
448
449
450
451
452
453
454
455
456
457
458
459
460
461
462
463
464
465
466
467
468
469
470
471
472
473
474
475
476
477
478
479
480
481
482
483
484
485
486
487
488
489
490
491
492
493
494
495
496
497
498
499
500
501
502
503
504
505
506
507
508
509
510
511
512
513
514
515
516
517
518
/* FS-Cache interface to CacheFiles
 *
 * Copyright (C) 2007 Red Hat, Inc. All Rights Reserved.
 * Written by David Howells (dhowells@redhat.com)
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public Licence
 * as published by the Free Software Foundation; either version
 * 2 of the Licence, or (at your option) any later version.
 */

#include <linux/slab.h>
#include <linux/mount.h>
#include "internal.h"

#define list_to_page(head) (list_entry((head)->prev, struct page, lru))

struct cachefiles_lookup_data {
	struct cachefiles_xattr	*auxdata;	/* auxiliary data */
	char			*key;		/* key path */
};

static int cachefiles_attr_changed(struct fscache_object *_object);

/*
 * allocate an object record for a cookie lookup and prepare the lookup data
 */
static struct fscache_object *cachefiles_alloc_object(
	struct fscache_cache *_cache,
	struct fscache_cookie *cookie)
{
	struct cachefiles_lookup_data *lookup_data;
	struct cachefiles_object *object;
	struct cachefiles_cache *cache;
	struct cachefiles_xattr *auxdata;
	unsigned keylen, auxlen;
	void *buffer;
	char *key;

	cache = container_of(_cache, struct cachefiles_cache, cache);

	_enter("{%s},%p,", cache->cache.identifier, cookie);

	lookup_data = kmalloc(sizeof(*lookup_data), cachefiles_gfp);
	if (!lookup_data)
		goto nomem_lookup_data;

	/* create a new object record and a temporary leaf image */
	object = kmem_cache_alloc(cachefiles_object_jar, cachefiles_gfp);
	if (!object)
		goto nomem_object;

	ASSERTCMP(object->backer, ==, NULL);

	BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
	atomic_set(&object->usage, 1);

	fscache_object_init(&object->fscache, cookie, &cache->cache);

	object->type = cookie->def->type;

	/* get hold of the raw key
	 * - stick the length on the front and leave space on the back for the
	 *   encoder
	 */
	buffer = kmalloc((2 + 512) + 3, cachefiles_gfp);
	if (!buffer)
		goto nomem_buffer;

	keylen = cookie->def->get_key(cookie->netfs_data, buffer + 2, 512);
	ASSERTCMP(keylen, <, 512);

	*(uint16_t *)buffer = keylen;
	((char *)buffer)[keylen + 2] = 0;
	((char *)buffer)[keylen + 3] = 0;
	((char *)buffer)[keylen + 4] = 0;

	/* turn the raw key into something that can work with as a filename */
	key = cachefiles_cook_key(buffer, keylen + 2, object->type);
	if (!key)
		goto nomem_key;

	/* get hold of the auxiliary data and prepend the object type */
	auxdata = buffer;
	auxlen = 0;
	if (cookie->def->get_aux) {
		auxlen = cookie->def->get_aux(cookie->netfs_data,
					      auxdata->data, 511);
		ASSERTCMP(auxlen, <, 511);
	}

	auxdata->len = auxlen + 1;
	auxdata->type = cookie->def->type;

	lookup_data->auxdata = auxdata;
	lookup_data->key = key;
	object->lookup_data = lookup_data;

	_leave(" = %p [%p]", &object->fscache, lookup_data);
	return &object->fscache;

nomem_key:
	kfree(buffer);
nomem_buffer:
	BUG_ON(test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
	kmem_cache_free(cachefiles_object_jar, object);
	fscache_object_destroyed(&cache->cache);
nomem_object:
	kfree(lookup_data);
nomem_lookup_data:
	_leave(" = -ENOMEM");
	return ERR_PTR(-ENOMEM);
}

/*
 * attempt to look up the nominated node in this cache
 * - return -ETIMEDOUT to be scheduled again
 */
static int cachefiles_lookup_object(struct fscache_object *_object)
{
	struct cachefiles_lookup_data *lookup_data;
	struct cachefiles_object *parent, *object;
	struct cachefiles_cache *cache;
	const struct cred *saved_cred;
	int ret;

	_enter("{OBJ%x}", _object->debug_id);

	cache = container_of(_object->cache, struct cachefiles_cache, cache);
	parent = container_of(_object->parent,
			      struct cachefiles_object, fscache);
	object = container_of(_object, struct cachefiles_object, fscache);
	lookup_data = object->lookup_data;

	ASSERTCMP(lookup_data, !=, NULL);

	/* look up the key, creating any missing bits */
	cachefiles_begin_secure(cache, &saved_cred);
	ret = cachefiles_walk_to_object(parent, object,
					lookup_data->key,
					lookup_data->auxdata);
	cachefiles_end_secure(cache, saved_cred);

	/* polish off by setting the attributes of non-index files */
	if (ret == 0 &&
	    object->fscache.cookie->def->type != FSCACHE_COOKIE_TYPE_INDEX)
		cachefiles_attr_changed(&object->fscache);

	if (ret < 0 && ret != -ETIMEDOUT) {
		if (ret != -ENOBUFS)
			printk(KERN_WARNING
			       "CacheFiles: Lookup failed error %d\n", ret);
		fscache_object_lookup_error(&object->fscache);
	}

	_leave(" [%d]", ret);
	return ret;
}

/*
 * indication of lookup completion
 */
static void cachefiles_lookup_complete(struct fscache_object *_object)
{
	struct cachefiles_object *object;

	object = container_of(_object, struct cachefiles_object, fscache);

	_enter("{OBJ%x,%p}", object->fscache.debug_id, object->lookup_data);

	if (object->lookup_data) {
		kfree(object->lookup_data->key);
		kfree(object->lookup_data->auxdata);
		kfree(object->lookup_data);
		object->lookup_data = NULL;
	}
}

/*
 * increment the usage count on an inode object (may fail if unmounting)
 */
static
struct fscache_object *cachefiles_grab_object(struct fscache_object *_object)
{
	struct cachefiles_object *object =
		container_of(_object, struct cachefiles_object, fscache);

	_enter("{OBJ%x,%d}", _object->debug_id, atomic_read(&object->usage));

#ifdef CACHEFILES_DEBUG_SLAB
	ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
#endif

	atomic_inc(&object->usage);
	return &object->fscache;
}

/*
 * update the auxiliary data for an object object on disk
 */
static void cachefiles_update_object(struct fscache_object *_object)
{
	struct cachefiles_object *object;
	struct cachefiles_xattr *auxdata;
	struct cachefiles_cache *cache;
	struct fscache_cookie *cookie;
	const struct cred *saved_cred;
	unsigned auxlen;

	_enter("{OBJ%x}", _object->debug_id);

	object = container_of(_object, struct cachefiles_object, fscache);
	cache = container_of(object->fscache.cache, struct cachefiles_cache,
			     cache);
	cookie = object->fscache.cookie;

	if (!cookie->def->get_aux) {
		_leave(" [no aux]");
		return;
	}

	auxdata = kmalloc(2 + 512 + 3, cachefiles_gfp);
	if (!auxdata) {
		_leave(" [nomem]");
		return;
	}

	auxlen = cookie->def->get_aux(cookie->netfs_data, auxdata->data, 511);
	ASSERTCMP(auxlen, <, 511);

	auxdata->len = auxlen + 1;
	auxdata->type = cookie->def->type;

	cachefiles_begin_secure(cache, &saved_cred);
	cachefiles_update_object_xattr(object, auxdata);
	cachefiles_end_secure(cache, saved_cred);
	kfree(auxdata);
	_leave("");
}

/*
 * discard the resources pinned by an object and effect retirement if
 * requested
 */
static void cachefiles_drop_object(struct fscache_object *_object)
{
	struct cachefiles_object *object;
	struct cachefiles_cache *cache;
	const struct cred *saved_cred;

	ASSERT(_object);

	object = container_of(_object, struct cachefiles_object, fscache);

	_enter("{OBJ%x,%d}",
	       object->fscache.debug_id, atomic_read(&object->usage));

	cache = container_of(object->fscache.cache,
			     struct cachefiles_cache, cache);

#ifdef CACHEFILES_DEBUG_SLAB
	ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
#endif

	/* delete retired objects */
	if (object->fscache.state == FSCACHE_OBJECT_RECYCLING &&
	    _object != cache->cache.fsdef
	    ) {
		_debug("- retire object OBJ%x", object->fscache.debug_id);
		cachefiles_begin_secure(cache, &saved_cred);
		cachefiles_delete_object(cache, object);
		cachefiles_end_secure(cache, saved_cred);
	}

	/* close the filesystem stuff attached to the object */
	if (object->backer != object->dentry)
		dput(object->backer);
	object->backer = NULL;

	/* note that the object is now inactive */
	if (test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags)) {
		write_lock(&cache->active_lock);
		if (!test_and_clear_bit(CACHEFILES_OBJECT_ACTIVE,
					&object->flags))
			BUG();
		rb_erase(&object->active_node, &cache->active_nodes);
		wake_up_bit(&object->flags, CACHEFILES_OBJECT_ACTIVE);
		write_unlock(&cache->active_lock);
	}

	dput(object->dentry);
	object->dentry = NULL;

	_leave("");
}

/*
 * dispose of a reference to an object
 */
static void cachefiles_put_object(struct fscache_object *_object)
{
	struct cachefiles_object *object;
	struct fscache_cache *cache;

	ASSERT(_object);

	object = container_of(_object, struct cachefiles_object, fscache);

	_enter("{OBJ%x,%d}",
	       object->fscache.debug_id, atomic_read(&object->usage));

#ifdef CACHEFILES_DEBUG_SLAB
	ASSERT((atomic_read(&object->usage) & 0xffff0000) != 0x6b6b0000);
#endif

	ASSERTIFCMP(object->fscache.parent,
		    object->fscache.parent->n_children, >, 0);

	if (atomic_dec_and_test(&object->usage)) {
		_debug("- kill object OBJ%x", object->fscache.debug_id);

		ASSERT(!test_bit(CACHEFILES_OBJECT_ACTIVE, &object->flags));
		ASSERTCMP(object->fscache.parent, ==, NULL);
		ASSERTCMP(object->backer, ==, NULL);
		ASSERTCMP(object->dentry, ==, NULL);
		ASSERTCMP(object->fscache.n_ops, ==, 0);
		ASSERTCMP(object->fscache.n_children, ==, 0);

		if (object->lookup_data) {
			kfree(object->lookup_data->key);
			kfree(object->lookup_data->auxdata);
			kfree(object->lookup_data);
			object->lookup_data = NULL;
		}

		cache = object->fscache.cache;
		fscache_object_destroy(&object->fscache);
		kmem_cache_free(cachefiles_object_jar, object);
		fscache_object_destroyed(cache);
	}

	_leave("");
}

/*
 * sync a cache
 */
static void cachefiles_sync_cache(struct fscache_cache *_cache)
{
	struct cachefiles_cache *cache;
	const struct cred *saved_cred;
	int ret;

	_enter("%p", _cache);

	cache = container_of(_cache, struct cachefiles_cache, cache);

	/* make sure all pages pinned by operations on behalf of the netfs are
	 * written to disc */
	cachefiles_begin_secure(cache, &saved_cred);
	down_read(&cache->mnt->mnt_sb->s_umount);
	ret = sync_filesystem(cache->mnt->mnt_sb);
	up_read(&cache->mnt->mnt_sb->s_umount);
	cachefiles_end_secure(cache, saved_cred);

	if (ret == -EIO)
		cachefiles_io_error(cache,
				    "Attempt to sync backing fs superblock"
				    " returned error %d",
				    ret);
}

/*
 * notification the attributes on an object have changed
 * - called with reads/writes excluded by FS-Cache
 */
static int cachefiles_attr_changed(struct fscache_object *_object)
{
	struct cachefiles_object *object;
	struct cachefiles_cache *cache;
	const struct cred *saved_cred;
	struct iattr newattrs;
	uint64_t ni_size;
	loff_t oi_size;
	int ret;

	_object->cookie->def->get_attr(_object->cookie->netfs_data, &ni_size);

	_enter("{OBJ%x},[%llu]",
	       _object->debug_id, (unsigned long long) ni_size);

	object = container_of(_object, struct cachefiles_object, fscache);
	cache = container_of(object->fscache.cache,
			     struct cachefiles_cache, cache);

	if (ni_size == object->i_size)
		return 0;

	if (!object->backer)
		return -ENOBUFS;

	ASSERT(S_ISREG(object->backer->d_inode->i_mode));

	fscache_set_store_limit(&object->fscache, ni_size);

	oi_size = i_size_read(object->backer->d_inode);
	if (oi_size == ni_size)
		return 0;

	cachefiles_begin_secure(cache, &saved_cred);
	mutex_lock(&object->backer->d_inode->i_mutex);

	/* if there's an extension to a partial page at the end of the backing
	 * file, we need to discard the partial page so that we pick up new
	 * data after it */
	if (oi_size & ~PAGE_MASK && ni_size > oi_size) {
		_debug("discard tail %llx", oi_size);
		newattrs.ia_valid = ATTR_SIZE;
		newattrs.ia_size = oi_size & PAGE_MASK;
		ret = notify_change(object->backer, &newattrs);
		if (ret < 0)
			goto truncate_failed;
	}

	newattrs.ia_valid = ATTR_SIZE;
	newattrs.ia_size = ni_size;
	ret = notify_change(object->backer, &newattrs);

truncate_failed:
	mutex_unlock(&object->backer->d_inode->i_mutex);
	cachefiles_end_secure(cache, saved_cred);

	if (ret == -EIO) {
		fscache_set_store_limit(&object->fscache, 0);
		cachefiles_io_error_obj(object, "Size set failed");
		ret = -ENOBUFS;
	}

	_leave(" = %d", ret);
	return ret;
}

/*
 * Invalidate an object
 */
static void cachefiles_invalidate_object(struct fscache_operation *op)
{
	struct cachefiles_object *object;
	struct cachefiles_cache *cache;
	const struct cred *saved_cred;
	struct path path;
	uint64_t ni_size;
	int ret;

	object = container_of(op->object, struct cachefiles_object, fscache);
	cache = container_of(object->fscache.cache,
			     struct cachefiles_cache, cache);

	op->object->cookie->def->get_attr(op->object->cookie->netfs_data,
					  &ni_size);

	_enter("{OBJ%x},[%llu]",
	       op->object->debug_id, (unsigned long long)ni_size);

	if (object->backer) {
		ASSERT(S_ISREG(object->backer->d_inode->i_mode));

		fscache_set_store_limit(&object->fscache, ni_size);

		path.dentry = object->backer;
		path.mnt = cache->mnt;

		cachefiles_begin_secure(cache, &saved_cred);
		ret = vfs_truncate(&path, 0);
		if (ret == 0)
			ret = vfs_truncate(&path, ni_size);
		cachefiles_end_secure(cache, saved_cred);

		if (ret != 0) {
			fscache_set_store_limit(&object->fscache, 0);
			if (ret == -EIO)
				cachefiles_io_error_obj(object,
							"Invalidate failed");
		}
	}

	fscache_op_complete(op, true);
	_leave("");
}

/*
 * dissociate a cache from all the pages it was backing
 */
static void cachefiles_dissociate_pages(struct fscache_cache *cache)
{
	_enter("");
}

const struct fscache_cache_ops cachefiles_cache_ops = {
	.name			= "cachefiles",
	.alloc_object		= cachefiles_alloc_object,
	.lookup_object		= cachefiles_lookup_object,
	.lookup_complete	= cachefiles_lookup_complete,
	.grab_object		= cachefiles_grab_object,
	.update_object		= cachefiles_update_object,
	.invalidate_object	= cachefiles_invalidate_object,
	.drop_object		= cachefiles_drop_object,
	.put_object		= cachefiles_put_object,
	.sync_cache		= cachefiles_sync_cache,
	.attr_changed		= cachefiles_attr_changed,
	.read_or_alloc_page	= cachefiles_read_or_alloc_page,
	.read_or_alloc_pages	= cachefiles_read_or_alloc_pages,
	.allocate_page		= cachefiles_allocate_page,
	.allocate_pages		= cachefiles_allocate_pages,
	.write_page		= cachefiles_write_page,
	.uncache_page		= cachefiles_uncache_page,
	.dissociate_pages	= cachefiles_dissociate_pages,
};