summaryrefslogtreecommitdiff
path: root/fs/ecryptfs/mmap.c
blob: 3014aa7199530660ac36e5ced86325ddd6cf7071 (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
519
520
521
522
523
524
525
526
527
528
529
530
531
532
533
534
535
536
537
538
539
540
541
542
543
544
545
546
547
548
549
550
551
552
553
554
555
556
557
558
559
560
561
562
563
564
565
566
567
568
569
570
571
572
573
574
575
576
577
578
579
580
581
582
583
584
585
586
587
588
589
590
591
592
593
594
595
596
597
598
599
600
601
602
603
604
605
606
607
608
609
610
611
612
613
614
615
616
617
618
619
620
621
622
623
624
625
626
627
628
629
630
631
632
633
634
635
636
637
638
639
640
641
642
643
644
645
646
647
648
649
650
651
652
653
654
655
656
657
658
659
660
661
662
663
664
665
666
667
668
669
670
671
672
673
674
675
676
677
678
679
680
681
682
683
684
685
686
687
688
689
690
691
692
693
694
695
696
697
698
699
700
701
702
703
704
705
706
707
708
709
710
711
712
713
714
715
716
717
718
719
720
721
722
723
724
725
726
727
728
729
730
731
732
733
734
735
736
737
738
739
740
741
742
743
744
745
746
747
748
749
750
751
752
753
754
755
756
757
758
759
760
761
762
763
764
765
766
767
768
769
770
771
772
773
774
775
776
777
778
779
780
781
782
783
784
785
786
787
788
789
790
791
792
793
794
795
796
797
798
799
800
801
802
/**
 * eCryptfs: Linux filesystem encryption layer
 * This is where eCryptfs coordinates the symmetric encryption and
 * decryption of the file data as it passes between the lower
 * encrypted file and the upper decrypted file.
 *
 * Copyright (C) 1997-2003 Erez Zadok
 * Copyright (C) 2001-2003 Stony Brook University
 * Copyright (C) 2004-2007 International Business Machines Corp.
 *   Author(s): Michael A. Halcrow <mahalcro@us.ibm.com>
 *
 * This program is free software; you can redistribute it and/or
 * modify it under the terms of the GNU General Public License as
 * published by the Free Software Foundation; either version 2 of the
 * License, or (at your option) any later version.
 *
 * This program is distributed in the hope that it will be useful, but
 * WITHOUT ANY WARRANTY; without even the implied warranty of
 * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the GNU
 * General Public License for more details.
 *
 * You should have received a copy of the GNU General Public License
 * along with this program; if not, write to the Free Software
 * Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA
 * 02111-1307, USA.
 */

#include <linux/pagemap.h>
#include <linux/writeback.h>
#include <linux/page-flags.h>
#include <linux/mount.h>
#include <linux/file.h>
#include <linux/crypto.h>
#include <linux/scatterlist.h>
#include "ecryptfs_kernel.h"

struct kmem_cache *ecryptfs_lower_page_cache;

/**
 * ecryptfs_get1page
 *
 * Get one page from cache or lower f/s, return error otherwise.
 *
 * Returns unlocked and up-to-date page (if ok), with increased
 * refcnt.
 */
static struct page *ecryptfs_get1page(struct file *file, int index)
{
	struct page *page;
	struct dentry *dentry;
	struct inode *inode;
	struct address_space *mapping;

	dentry = file->f_path.dentry;
	inode = dentry->d_inode;
	mapping = inode->i_mapping;
	page = read_cache_page(mapping, index,
			       (filler_t *)mapping->a_ops->readpage,
			       (void *)file);
	if (IS_ERR(page))
		goto out;
	wait_on_page_locked(page);
out:
	return page;
}

static
int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros);

/**
 * ecryptfs_fill_zeros
 * @file: The ecryptfs file
 * @new_length: The new length of the data in the underlying file;
 *              everything between the prior end of the file and the
 *              new end of the file will be filled with zero's.
 *              new_length must be greater than  current length
 *
 * Function for handling lseek-ing past the end of the file.
 *
 * This function does not support shrinking, only growing a file.
 *
 * Returns zero on success; non-zero otherwise.
 */
int ecryptfs_fill_zeros(struct file *file, loff_t new_length)
{
	int rc = 0;
	struct dentry *dentry = file->f_path.dentry;
	struct inode *inode = dentry->d_inode;
	pgoff_t old_end_page_index = 0;
	pgoff_t index = old_end_page_index;
	int old_end_pos_in_page = -1;
	pgoff_t new_end_page_index;
	int new_end_pos_in_page;
	loff_t cur_length = i_size_read(inode);

	if (cur_length != 0) {
		index = old_end_page_index =
		    ((cur_length - 1) >> PAGE_CACHE_SHIFT);
		old_end_pos_in_page = ((cur_length - 1) & ~PAGE_CACHE_MASK);
	}
	new_end_page_index = ((new_length - 1) >> PAGE_CACHE_SHIFT);
	new_end_pos_in_page = ((new_length - 1) & ~PAGE_CACHE_MASK);
	ecryptfs_printk(KERN_DEBUG, "old_end_page_index = [0x%.16x]; "
			"old_end_pos_in_page = [%d]; "
			"new_end_page_index = [0x%.16x]; "
			"new_end_pos_in_page = [%d]\n",
			old_end_page_index, old_end_pos_in_page,
			new_end_page_index, new_end_pos_in_page);
	if (old_end_page_index == new_end_page_index) {
		/* Start and end are in the same page; we just need to
		 * set a portion of the existing page to zero's */
		rc = write_zeros(file, index, (old_end_pos_in_page + 1),
				 (new_end_pos_in_page - old_end_pos_in_page));
		if (rc)
			ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
					"index=[0x%.16x], "
					"old_end_pos_in_page=[d], "
					"(PAGE_CACHE_SIZE - new_end_pos_in_page"
					"=[%d]"
					")=[d]) returned [%d]\n", file, index,
					old_end_pos_in_page,
					new_end_pos_in_page,
					(PAGE_CACHE_SIZE - new_end_pos_in_page),
					rc);
		goto out;
	}
	/* Fill the remainder of the previous last page with zeros */
	rc = write_zeros(file, index, (old_end_pos_in_page + 1),
			 ((PAGE_CACHE_SIZE - 1) - old_end_pos_in_page));
	if (rc) {
		ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
				"index=[0x%.16x], old_end_pos_in_page=[d], "
				"(PAGE_CACHE_SIZE - old_end_pos_in_page)=[d]) "
				"returned [%d]\n", file, index,
				old_end_pos_in_page,
				(PAGE_CACHE_SIZE - old_end_pos_in_page), rc);
		goto out;
	}
	index++;
	while (index < new_end_page_index) {
		/* Fill all intermediate pages with zeros */
		rc = write_zeros(file, index, 0, PAGE_CACHE_SIZE);
		if (rc) {
			ecryptfs_printk(KERN_ERR, "write_zeros(file=[%p], "
					"index=[0x%.16x], "
					"old_end_pos_in_page=[d], "
					"(PAGE_CACHE_SIZE - new_end_pos_in_page"
					"=[%d]"
					")=[d]) returned [%d]\n", file, index,
					old_end_pos_in_page,
					new_end_pos_in_page,
					(PAGE_CACHE_SIZE - new_end_pos_in_page),
					rc);
			goto out;
		}
		index++;
	}
	/* Fill the portion at the beginning of the last new page with
	 * zero's */
	rc = write_zeros(file, index, 0, (new_end_pos_in_page + 1));
	if (rc) {
		ecryptfs_printk(KERN_ERR, "write_zeros(file="
				"[%p], index=[0x%.16x], 0, "
				"new_end_pos_in_page=[%d]"
				"returned [%d]\n", file, index,
				new_end_pos_in_page, rc);
		goto out;
	}
out:
	return rc;
}

/**
 * ecryptfs_writepage
 * @page: Page that is locked before this call is made
 *
 * Returns zero on success; non-zero otherwise
 */
static int ecryptfs_writepage(struct page *page, struct writeback_control *wbc)
{
	struct ecryptfs_page_crypt_context ctx;
	int rc;

	ctx.page = page;
	ctx.mode = ECRYPTFS_WRITEPAGE_MODE;
	ctx.param.wbc = wbc;
	rc = ecryptfs_encrypt_page(&ctx);
	if (rc) {
		ecryptfs_printk(KERN_WARNING, "Error encrypting "
				"page (upper index [0x%.16x])\n", page->index);
		ClearPageUptodate(page);
		goto out;
	}
	SetPageUptodate(page);
	unlock_page(page);
out:
	return rc;
}

/**
 * Reads the data from the lower file file at index lower_page_index
 * and copies that data into page.
 *
 * @param page	Page to fill
 * @param lower_page_index Index of the page in the lower file to get
 */
int ecryptfs_do_readpage(struct file *file, struct page *page,
			 pgoff_t lower_page_index)
{
	int rc;
	struct dentry *dentry;
	struct file *lower_file;
	struct dentry *lower_dentry;
	struct inode *inode;
	struct inode *lower_inode;
	char *page_data;
	struct page *lower_page = NULL;
	char *lower_page_data;
	const struct address_space_operations *lower_a_ops;

	dentry = file->f_path.dentry;
	lower_file = ecryptfs_file_to_lower(file);
	lower_dentry = ecryptfs_dentry_to_lower(dentry);
	inode = dentry->d_inode;
	lower_inode = ecryptfs_inode_to_lower(inode);
	lower_a_ops = lower_inode->i_mapping->a_ops;
	lower_page = read_cache_page(lower_inode->i_mapping, lower_page_index,
				     (filler_t *)lower_a_ops->readpage,
				     (void *)lower_file);
	if (IS_ERR(lower_page)) {
		rc = PTR_ERR(lower_page);
		lower_page = NULL;
		ecryptfs_printk(KERN_ERR, "Error reading from page cache\n");
		goto out;
	}
	wait_on_page_locked(lower_page);
	page_data = kmap_atomic(page, KM_USER0);
	lower_page_data = kmap_atomic(lower_page, KM_USER1);
	memcpy(page_data, lower_page_data, PAGE_CACHE_SIZE);
	kunmap_atomic(lower_page_data, KM_USER1);
	kunmap_atomic(page_data, KM_USER0);
	rc = 0;
out:
	if (likely(lower_page))
		page_cache_release(lower_page);
	if (rc == 0)
		SetPageUptodate(page);
	else
		ClearPageUptodate(page);
	return rc;
}
/**
 *   Header Extent:
 *     Octets 0-7:        Unencrypted file size (big-endian)
 *     Octets 8-15:       eCryptfs special marker
 *     Octets 16-19:      Flags
 *      Octet 16:         File format version number (between 0 and 255)
 *      Octets 17-18:     Reserved
 *      Octet 19:         Bit 1 (lsb): Reserved
 *                        Bit 2: Encrypted?
 *                        Bits 3-8: Reserved
 *     Octets 20-23:      Header extent size (big-endian)
 *     Octets 24-25:      Number of header extents at front of file
 *                        (big-endian)
 *     Octet  26:         Begin RFC 2440 authentication token packet set
 */
static void set_header_info(char *page_virt,
			    struct ecryptfs_crypt_stat *crypt_stat)
{
	size_t written;
	int save_num_header_extents_at_front =
		crypt_stat->num_header_extents_at_front;

	crypt_stat->num_header_extents_at_front = 1;
	ecryptfs_write_header_metadata(page_virt + 20, crypt_stat, &written);
	crypt_stat->num_header_extents_at_front =
		save_num_header_extents_at_front;
}

/**
 * ecryptfs_readpage
 * @file: This is an ecryptfs file
 * @page: ecryptfs associated page to stick the read data into
 *
 * Read in a page, decrypting if necessary.
 *
 * Returns zero on success; non-zero on error.
 */
static int ecryptfs_readpage(struct file *file, struct page *page)
{
	int rc = 0;
	struct ecryptfs_crypt_stat *crypt_stat;

	BUG_ON(!(file && file->f_path.dentry && file->f_path.dentry->d_inode));
	crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
			->crypt_stat;
	if (!crypt_stat
	    || !(crypt_stat->flags & ECRYPTFS_ENCRYPTED)
	    || (crypt_stat->flags & ECRYPTFS_NEW_FILE)) {
		ecryptfs_printk(KERN_DEBUG,
				"Passing through unencrypted page\n");
		rc = ecryptfs_do_readpage(file, page, page->index);
		if (rc) {
			ecryptfs_printk(KERN_ERR, "Error reading page; rc = "
					"[%d]\n", rc);
			goto out;
		}
	} else if (crypt_stat->flags & ECRYPTFS_VIEW_AS_ENCRYPTED) {
		if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR) {
			int num_pages_in_header_region =
				(crypt_stat->header_extent_size
				 / PAGE_CACHE_SIZE);

			if (page->index < num_pages_in_header_region) {
				char *page_virt;

				page_virt = kmap_atomic(page, KM_USER0);
				memset(page_virt, 0, PAGE_CACHE_SIZE);
				if (page->index == 0) {
					rc = ecryptfs_read_xattr_region(
						page_virt, file->f_path.dentry);
					set_header_info(page_virt, crypt_stat);
				}
				kunmap_atomic(page_virt, KM_USER0);
				if (rc) {
					printk(KERN_ERR "Error reading xattr "
					       "region\n");
					goto out;
				}
			} else {
				rc = ecryptfs_do_readpage(
					file, page,
					(page->index
					 - num_pages_in_header_region));
				if (rc) {
					printk(KERN_ERR "Error reading page; "
					       "rc = [%d]\n", rc);
					goto out;
				}
			}
		} else {
			rc = ecryptfs_do_readpage(file, page, page->index);
			if (rc) {
				printk(KERN_ERR "Error reading page; rc = "
				       "[%d]\n", rc);
				goto out;
			}
		}
	} else {
		rc = ecryptfs_decrypt_page(file, page);
		if (rc) {
			ecryptfs_printk(KERN_ERR, "Error decrypting page; "
					"rc = [%d]\n", rc);
			goto out;
		}
	}
	SetPageUptodate(page);
out:
	if (rc)
		ClearPageUptodate(page);
	ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
			page->index);
	unlock_page(page);
	return rc;
}

/**
 * Called with lower inode mutex held.
 */
static int fill_zeros_to_end_of_page(struct page *page, unsigned int to)
{
	struct inode *inode = page->mapping->host;
	int end_byte_in_page;
	char *page_virt;

	if ((i_size_read(inode) / PAGE_CACHE_SIZE) != page->index)
		goto out;
	end_byte_in_page = i_size_read(inode) % PAGE_CACHE_SIZE;
	if (to > end_byte_in_page)
		end_byte_in_page = to;
	page_virt = kmap_atomic(page, KM_USER0);
	memset((page_virt + end_byte_in_page), 0,
	       (PAGE_CACHE_SIZE - end_byte_in_page));
	kunmap_atomic(page_virt, KM_USER0);
out:
	return 0;
}

static int ecryptfs_prepare_write(struct file *file, struct page *page,
				  unsigned from, unsigned to)
{
	int rc = 0;

	if (from == 0 && to == PAGE_CACHE_SIZE)
		goto out;	/* If we are writing a full page, it will be
				   up to date. */
	if (!PageUptodate(page))
		rc = ecryptfs_do_readpage(file, page, page->index);
out:
	return rc;
}

int ecryptfs_writepage_and_release_lower_page(struct page *lower_page,
					      struct inode *lower_inode,
					      struct writeback_control *wbc)
{
	int rc = 0;

	rc = lower_inode->i_mapping->a_ops->writepage(lower_page, wbc);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error calling lower writepage(); "
				"rc = [%d]\n", rc);
		goto out;
	}
	lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
	page_cache_release(lower_page);
out:
	return rc;
}

static void ecryptfs_release_lower_page(struct page *lower_page)
{
	unlock_page(lower_page);
	page_cache_release(lower_page);
}

/**
 * ecryptfs_write_inode_size_to_header
 *
 * Writes the lower file size to the first 8 bytes of the header.
 *
 * Returns zero on success; non-zero on error.
 */
static int ecryptfs_write_inode_size_to_header(struct file *lower_file,
					       struct inode *lower_inode,
					       struct inode *inode)
{
	int rc = 0;
	struct page *header_page;
	char *header_virt;
	const struct address_space_operations *lower_a_ops;
	u64 file_size;

	header_page = grab_cache_page(lower_inode->i_mapping, 0);
	if (!header_page) {
		ecryptfs_printk(KERN_ERR, "grab_cache_page for "
				"lower_page_index 0 failed\n");
		rc = -EINVAL;
		goto out;
	}
	lower_a_ops = lower_inode->i_mapping->a_ops;
	rc = lower_a_ops->prepare_write(lower_file, header_page, 0, 8);
	file_size = (u64)i_size_read(inode);
	ecryptfs_printk(KERN_DEBUG, "Writing size: [0x%.16x]\n", file_size);
	file_size = cpu_to_be64(file_size);
	header_virt = kmap_atomic(header_page, KM_USER0);
	memcpy(header_virt, &file_size, sizeof(u64));
	kunmap_atomic(header_virt, KM_USER0);
	rc = lower_a_ops->commit_write(lower_file, header_page, 0, 8);
	if (rc < 0)
		ecryptfs_printk(KERN_ERR, "Error commiting header page "
				"write\n");
	ecryptfs_release_lower_page(header_page);
	lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
	mark_inode_dirty_sync(inode);
out:
	return rc;
}

static int ecryptfs_write_inode_size_to_xattr(struct inode *lower_inode,
					      struct inode *inode,
					      struct dentry *ecryptfs_dentry,
					      int lower_i_mutex_held)
{
	ssize_t size;
	void *xattr_virt;
	struct dentry *lower_dentry;
	u64 file_size;
	int rc;

	xattr_virt = kmem_cache_alloc(ecryptfs_xattr_cache, GFP_KERNEL);
	if (!xattr_virt) {
		printk(KERN_ERR "Out of memory whilst attempting to write "
		       "inode size to xattr\n");
		rc = -ENOMEM;
		goto out;
	}
	lower_dentry = ecryptfs_dentry_to_lower(ecryptfs_dentry);
	if (!lower_dentry->d_inode->i_op->getxattr) {
		printk(KERN_WARNING
		       "No support for setting xattr in lower filesystem\n");
		rc = -ENOSYS;
		kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
		goto out;
	}
	if (!lower_i_mutex_held)
		mutex_lock(&lower_dentry->d_inode->i_mutex);
	size = lower_dentry->d_inode->i_op->getxattr(lower_dentry,
						     ECRYPTFS_XATTR_NAME,
						     xattr_virt,
						     PAGE_CACHE_SIZE);
	if (!lower_i_mutex_held)
		mutex_unlock(&lower_dentry->d_inode->i_mutex);
	if (size < 0)
		size = 8;
	file_size = (u64)i_size_read(inode);
	file_size = cpu_to_be64(file_size);
	memcpy(xattr_virt, &file_size, sizeof(u64));
	if (!lower_i_mutex_held)
		mutex_lock(&lower_dentry->d_inode->i_mutex);
	rc = lower_dentry->d_inode->i_op->setxattr(lower_dentry,
						   ECRYPTFS_XATTR_NAME,
						   xattr_virt, size, 0);
	if (!lower_i_mutex_held)
		mutex_unlock(&lower_dentry->d_inode->i_mutex);
	if (rc)
		printk(KERN_ERR "Error whilst attempting to write inode size "
		       "to lower file xattr; rc = [%d]\n", rc);
	kmem_cache_free(ecryptfs_xattr_cache, xattr_virt);
out:
	return rc;
}

int
ecryptfs_write_inode_size_to_metadata(struct file *lower_file,
				      struct inode *lower_inode,
				      struct inode *inode,
				      struct dentry *ecryptfs_dentry,
				      int lower_i_mutex_held)
{
	struct ecryptfs_crypt_stat *crypt_stat;

	crypt_stat = &ecryptfs_inode_to_private(inode)->crypt_stat;
	if (crypt_stat->flags & ECRYPTFS_METADATA_IN_XATTR)
		return ecryptfs_write_inode_size_to_xattr(lower_inode, inode,
							  ecryptfs_dentry,
							  lower_i_mutex_held);
	else
		return ecryptfs_write_inode_size_to_header(lower_file,
							   lower_inode,
							   inode);
}

int ecryptfs_get_lower_page(struct page **lower_page, struct inode *lower_inode,
			    struct file *lower_file,
			    unsigned long lower_page_index, int byte_offset,
			    int region_bytes)
{
	int rc = 0;

	*lower_page = grab_cache_page(lower_inode->i_mapping, lower_page_index);
	if (!(*lower_page)) {
		rc = -EINVAL;
		ecryptfs_printk(KERN_ERR, "Error attempting to grab "
				"lower page with index [0x%.16x]\n",
				lower_page_index);
		goto out;
	}
	rc = lower_inode->i_mapping->a_ops->prepare_write(lower_file,
							  (*lower_page),
							  byte_offset,
							  region_bytes);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "prepare_write for "
				"lower_page_index = [0x%.16x] failed; rc = "
				"[%d]\n", lower_page_index, rc);
	}
out:
	if (rc && (*lower_page)) {
		ecryptfs_release_lower_page(*lower_page);
		(*lower_page) = NULL;
	}
	return rc;
}

/**
 * ecryptfs_commit_lower_page
 *
 * Returns zero on success; non-zero on error
 */
int
ecryptfs_commit_lower_page(struct page *lower_page, struct inode *lower_inode,
			   struct file *lower_file, int byte_offset,
			   int region_size)
{
	int rc = 0;

	rc = lower_inode->i_mapping->a_ops->commit_write(
		lower_file, lower_page, byte_offset, region_size);
	if (rc < 0) {
		ecryptfs_printk(KERN_ERR,
				"Error committing write; rc = [%d]\n", rc);
	} else
		rc = 0;
	ecryptfs_release_lower_page(lower_page);
	return rc;
}

/**
 * ecryptfs_copy_page_to_lower
 *
 * Used for plaintext pass-through; no page index interpolation
 * required.
 */
int ecryptfs_copy_page_to_lower(struct page *page, struct inode *lower_inode,
				struct file *lower_file)
{
	int rc = 0;
	struct page *lower_page;

	rc = ecryptfs_get_lower_page(&lower_page, lower_inode, lower_file,
				     page->index, 0, PAGE_CACHE_SIZE);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error attempting to get page "
				"at index [0x%.16x]\n", page->index);
		goto out;
	}
	/* TODO: aops */
	memcpy((char *)page_address(lower_page), page_address(page),
	       PAGE_CACHE_SIZE);
	rc = ecryptfs_commit_lower_page(lower_page, lower_inode, lower_file,
					0, PAGE_CACHE_SIZE);
	if (rc)
		ecryptfs_printk(KERN_ERR, "Error attempting to commit page "
				"at index [0x%.16x]\n", page->index);
out:
	return rc;
}

struct kmem_cache *ecryptfs_xattr_cache;

/**
 * ecryptfs_commit_write
 * @file: The eCryptfs file object
 * @page: The eCryptfs page
 * @from: Ignored (we rotate the page IV on each write)
 * @to: Ignored
 *
 * This is where we encrypt the data and pass the encrypted data to
 * the lower filesystem.  In OpenPGP-compatible mode, we operate on
 * entire underlying packets.
 */
static int ecryptfs_commit_write(struct file *file, struct page *page,
				 unsigned from, unsigned to)
{
	struct ecryptfs_page_crypt_context ctx;
	loff_t pos;
	struct inode *inode;
	struct inode *lower_inode;
	struct file *lower_file;
	struct ecryptfs_crypt_stat *crypt_stat;
	int rc;

	inode = page->mapping->host;
	lower_inode = ecryptfs_inode_to_lower(inode);
	lower_file = ecryptfs_file_to_lower(file);
	mutex_lock(&lower_inode->i_mutex);
	crypt_stat = &ecryptfs_inode_to_private(file->f_path.dentry->d_inode)
				->crypt_stat;
	if (crypt_stat->flags & ECRYPTFS_NEW_FILE) {
		ecryptfs_printk(KERN_DEBUG, "ECRYPTFS_NEW_FILE flag set in "
			"crypt_stat at memory location [%p]\n", crypt_stat);
		crypt_stat->flags &= ~(ECRYPTFS_NEW_FILE);
	} else
		ecryptfs_printk(KERN_DEBUG, "Not a new file\n");
	ecryptfs_printk(KERN_DEBUG, "Calling fill_zeros_to_end_of_page"
			"(page w/ index = [0x%.16x], to = [%d])\n", page->index,
			to);
	rc = fill_zeros_to_end_of_page(page, to);
	if (rc) {
		ecryptfs_printk(KERN_WARNING, "Error attempting to fill "
				"zeros in page with index = [0x%.16x]\n",
				page->index);
		goto out;
	}
	ctx.page = page;
	ctx.mode = ECRYPTFS_PREPARE_COMMIT_MODE;
	ctx.param.lower_file = lower_file;
	rc = ecryptfs_encrypt_page(&ctx);
	if (rc) {
		ecryptfs_printk(KERN_WARNING, "Error encrypting page (upper "
				"index [0x%.16x])\n", page->index);
		goto out;
	}
	inode->i_blocks = lower_inode->i_blocks;
	pos = (page->index << PAGE_CACHE_SHIFT) + to;
	if (pos > i_size_read(inode)) {
		i_size_write(inode, pos);
		ecryptfs_printk(KERN_DEBUG, "Expanded file size to "
				"[0x%.16x]\n", i_size_read(inode));
	}
	rc = ecryptfs_write_inode_size_to_metadata(lower_file, lower_inode,
						   inode, file->f_dentry,
						   ECRYPTFS_LOWER_I_MUTEX_HELD);
	if (rc)
		printk(KERN_ERR "Error writing inode size to metadata; "
		       "rc = [%d]\n", rc);
	lower_inode->i_mtime = lower_inode->i_ctime = CURRENT_TIME;
	mark_inode_dirty_sync(inode);
out:
	if (rc < 0)
		ClearPageUptodate(page);
	else
		SetPageUptodate(page);
	mutex_unlock(&lower_inode->i_mutex);
	return rc;
}

/**
 * write_zeros
 * @file: The ecryptfs file
 * @index: The index in which we are writing
 * @start: The position after the last block of data
 * @num_zeros: The number of zeros to write
 *
 * Write a specified number of zero's to a page.
 *
 * (start + num_zeros) must be less than or equal to PAGE_CACHE_SIZE
 */
static
int write_zeros(struct file *file, pgoff_t index, int start, int num_zeros)
{
	int rc = 0;
	struct page *tmp_page;
	char *tmp_page_virt;

	tmp_page = ecryptfs_get1page(file, index);
	if (IS_ERR(tmp_page)) {
		ecryptfs_printk(KERN_ERR, "Error getting page at index "
				"[0x%.16x]\n", index);
		rc = PTR_ERR(tmp_page);
		goto out;
	}
	rc = ecryptfs_prepare_write(file, tmp_page, start, start + num_zeros);
	if (rc) {
		ecryptfs_printk(KERN_ERR, "Error preparing to write zero's "
				"to remainder of page at index [0x%.16x]\n",
				index);
		page_cache_release(tmp_page);
		goto out;
	}
	tmp_page_virt = kmap_atomic(tmp_page, KM_USER0);
	memset(((char *)tmp_page_virt + start), 0, num_zeros);
	kunmap_atomic(tmp_page_virt, KM_USER0);
	rc = ecryptfs_commit_write(file, tmp_page, start, start + num_zeros);
	if (rc < 0) {
		ecryptfs_printk(KERN_ERR, "Error attempting to write zero's "
				"to remainder of page at index [0x%.16x]\n",
				index);
		page_cache_release(tmp_page);
		goto out;
	}
	rc = 0;
	page_cache_release(tmp_page);
out:
	return rc;
}

static sector_t ecryptfs_bmap(struct address_space *mapping, sector_t block)
{
	int rc = 0;
	struct inode *inode;
	struct inode *lower_inode;

	inode = (struct inode *)mapping->host;
	lower_inode = ecryptfs_inode_to_lower(inode);
	if (lower_inode->i_mapping->a_ops->bmap)
		rc = lower_inode->i_mapping->a_ops->bmap(lower_inode->i_mapping,
							 block);
	return rc;
}

static void ecryptfs_sync_page(struct page *page)
{
	struct inode *inode;
	struct inode *lower_inode;
	struct page *lower_page;

	inode = page->mapping->host;
	lower_inode = ecryptfs_inode_to_lower(inode);
	/* NOTE: Recently swapped with grab_cache_page(), since
	 * sync_page() just makes sure that pending I/O gets done. */
	lower_page = find_lock_page(lower_inode->i_mapping, page->index);
	if (!lower_page) {
		ecryptfs_printk(KERN_DEBUG, "find_lock_page failed\n");
		return;
	}
	lower_page->mapping->a_ops->sync_page(lower_page);
	ecryptfs_printk(KERN_DEBUG, "Unlocking page with index = [0x%.16x]\n",
			lower_page->index);
	unlock_page(lower_page);
	page_cache_release(lower_page);
}

struct address_space_operations ecryptfs_aops = {
	.writepage = ecryptfs_writepage,
	.readpage = ecryptfs_readpage,
	.prepare_write = ecryptfs_prepare_write,
	.commit_write = ecryptfs_commit_write,
	.bmap = ecryptfs_bmap,
	.sync_page = ecryptfs_sync_page,
};