aboutsummaryrefslogtreecommitdiff
path: root/fs/ext2/dir.c
blob: a0995eb2dc232c2b7ddc79df644482a9a651c9e0 (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
/*
 *  linux/fs/ext2/dir.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/dir.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  ext2 directory handling functions
 *
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 *
 * All code that works with directory layout had been switched to pagecache
 * and moved here. AV
 */

#include "ext2.h"
#include <linux/buffer_head.h>
#include <linux/pagemap.h>
#include <linux/swap.h>

typedef struct ext2_dir_entry_2 ext2_dirent;

static inline unsigned ext2_rec_len_from_disk(__le16 dlen)
{
	unsigned len = le16_to_cpu(dlen);

	if (len == EXT2_MAX_REC_LEN)
		return 1 << 16;
	return len;
}

static inline __le16 ext2_rec_len_to_disk(unsigned len)
{
	if (len == (1 << 16))
		return cpu_to_le16(EXT2_MAX_REC_LEN);
	else if (len > (1 << 16))
		BUG();
	return cpu_to_le16(len);
}

/*
 * ext2 uses block-sized chunks. Arguably, sector-sized ones would be
 * more robust, but we have what we have
 */
static inline unsigned ext2_chunk_size(struct inode *inode)
{
	return inode->i_sb->s_blocksize;
}

static inline void ext2_put_page(struct page *page)
{
	kunmap(page);
	page_cache_release(page);
}

static inline unsigned long dir_pages(struct inode *inode)
{
	return (inode->i_size+PAGE_CACHE_SIZE-1)>>PAGE_CACHE_SHIFT;
}

/*
 * Return the offset into page `page_nr' of the last valid
 * byte in that page, plus one.
 */
static unsigned
ext2_last_byte(struct inode *inode, unsigned long page_nr)
{
	unsigned last_byte = inode->i_size;

	last_byte -= page_nr << PAGE_CACHE_SHIFT;
	if (last_byte > PAGE_CACHE_SIZE)
		last_byte = PAGE_CACHE_SIZE;
	return last_byte;
}

static int ext2_commit_chunk(struct page *page, loff_t pos, unsigned len)
{
	struct address_space *mapping = page->mapping;
	struct inode *dir = mapping->host;
	int err = 0;

	dir->i_version++;
	block_write_end(NULL, mapping, pos, len, len, page, NULL);

	if (pos+len > dir->i_size) {
		i_size_write(dir, pos+len);
		mark_inode_dirty(dir);
	}

	if (IS_DIRSYNC(dir))
		err = write_one_page(page, 1);
	else
		unlock_page(page);

	return err;
}

static void ext2_check_page(struct page *page)
{
	struct inode *dir = page->mapping->host;
	struct super_block *sb = dir->i_sb;
	unsigned chunk_size = ext2_chunk_size(dir);
	char *kaddr = page_address(page);
	u32 max_inumber = le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count);
	unsigned offs, rec_len;
	unsigned limit = PAGE_CACHE_SIZE;
	ext2_dirent *p;
	char *error;

	if ((dir->i_size >> PAGE_CACHE_SHIFT) == page->index) {
		limit = dir->i_size & ~PAGE_CACHE_MASK;
		if (limit & (chunk_size - 1))
			goto Ebadsize;
		if (!limit)
			goto out;
	}
	for (offs = 0; offs <= limit - EXT2_DIR_REC_LEN(1); offs += rec_len) {
		p = (ext2_dirent *)(kaddr + offs);
		rec_len = ext2_rec_len_from_disk(p->rec_len);

		if (rec_len < EXT2_DIR_REC_LEN(1))
			goto Eshort;
		if (rec_len & 3)
			goto Ealign;
		if (rec_len < EXT2_DIR_REC_LEN(p->name_len))
			goto Enamelen;
		if (((offs + rec_len - 1) ^ offs) & ~(chunk_size-1))
			goto Espan;
		if (le32_to_cpu(p->inode) > max_inumber)
			goto Einumber;
	}
	if (offs != limit)
		goto Eend;
out:
	SetPageChecked(page);
	return;

	/* Too bad, we had an error */

Ebadsize:
	ext2_error(sb, "ext2_check_page",
		"size of directory #%lu is not a multiple of chunk size",
		dir->i_ino
	);
	goto fail;
Eshort:
	error = "rec_len is smaller than minimal";
	goto bad_entry;
Ealign:
	error = "unaligned directory entry";
	goto bad_entry;
Enamelen:
	error = "rec_len is too small for name_len";
	goto bad_entry;
Espan:
	error = "directory entry across blocks";
	goto bad_entry;
Einumber:
	error = "inode out of bounds";
bad_entry:
	ext2_error (sb, "ext2_check_page", "bad entry in directory #%lu: %s - "
		"offset=%lu, inode=%lu, rec_len=%d, name_len=%d",
		dir->i_ino, error, (page->index<<PAGE_CACHE_SHIFT)+offs,
		(unsigned long) le32_to_cpu(p->inode),
		rec_len, p->name_len);
	goto fail;
Eend:
	p = (ext2_dirent *)(kaddr + offs);
	ext2_error (sb, "ext2_check_page",
		"entry in directory #%lu spans the page boundary"
		"offset=%lu, inode=%lu",
		dir->i_ino, (page->index<<PAGE_CACHE_SHIFT)+offs,
		(unsigned long) le32_to_cpu(p->inode));
fail:
	SetPageChecked(page);
	SetPageError(page);
}

static struct page * ext2_get_page(struct inode *dir, unsigned long n)
{
	struct address_space *mapping = dir->i_mapping;
	struct page *page = read_mapping_page(mapping, n, NULL);
	if (!IS_ERR(page)) {
		kmap(page);
		if (!PageChecked(page))
			ext2_check_page(page);
		if (PageError(page))
			goto fail;
	}
	return page;

fail:
	ext2_put_page(page);
	return ERR_PTR(-EIO);
}

/*
 * NOTE! unlike strncmp, ext2_match returns 1 for success, 0 for failure.
 *
 * len <= EXT2_NAME_LEN and de != NULL are guaranteed by caller.
 */
static inline int ext2_match (int len, const char * const name,
					struct ext2_dir_entry_2 * de)
{
	if (len != de->name_len)
		return 0;
	if (!de->inode)
		return 0;
	return !memcmp(name, de->name, len);
}

/*
 * p is at least 6 bytes before the end of page
 */
static inline ext2_dirent *ext2_next_entry(ext2_dirent *p)
{
	return (ext2_dirent *)((char *)p +
			ext2_rec_len_from_disk(p->rec_len));
}

static inline unsigned 
ext2_validate_entry(char *base, unsigned offset, unsigned mask)
{
	ext2_dirent *de = (ext2_dirent*)(base + offset);
	ext2_dirent *p = (ext2_dirent*)(base + (offset&mask));
	while ((char*)p < (char*)de) {
		if (p->rec_len == 0)
			break;
		p = ext2_next_entry(p);
	}
	return (char *)p - base;
}

static unsigned char ext2_filetype_table[EXT2_FT_MAX] = {
	[EXT2_FT_UNKNOWN]	= DT_UNKNOWN,
	[EXT2_FT_REG_FILE]	= DT_REG,
	[EXT2_FT_DIR]		= DT_DIR,
	[EXT2_FT_CHRDEV]	= DT_CHR,
	[EXT2_FT_BLKDEV]	= DT_BLK,
	[EXT2_FT_FIFO]		= DT_FIFO,
	[EXT2_FT_SOCK]		= DT_SOCK,
	[EXT2_FT_SYMLINK]	= DT_LNK,
};

#define S_SHIFT 12
static unsigned char ext2_type_by_mode[S_IFMT >> S_SHIFT] = {
	[S_IFREG >> S_SHIFT]	= EXT2_FT_REG_FILE,
	[S_IFDIR >> S_SHIFT]	= EXT2_FT_DIR,
	[S_IFCHR >> S_SHIFT]	= EXT2_FT_CHRDEV,
	[S_IFBLK >> S_SHIFT]	= EXT2_FT_BLKDEV,
	[S_IFIFO >> S_SHIFT]	= EXT2_FT_FIFO,
	[S_IFSOCK >> S_SHIFT]	= EXT2_FT_SOCK,
	[S_IFLNK >> S_SHIFT]	= EXT2_FT_SYMLINK,
};

static inline void ext2_set_de_type(ext2_dirent *de, struct inode *inode)
{
	mode_t mode = inode->i_mode;
	if (EXT2_HAS_INCOMPAT_FEATURE(inode->i_sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
		de->file_type = ext2_type_by_mode[(mode & S_IFMT)>>S_SHIFT];
	else
		de->file_type = 0;
}

static int
ext2_readdir (struct file * filp, void * dirent, filldir_t filldir)
{
	loff_t pos = filp->f_pos;
	struct inode *inode = filp->f_path.dentry->d_inode;
	struct super_block *sb = inode->i_sb;
	unsigned int offset = pos & ~PAGE_CACHE_MASK;
	unsigned long n = pos >> PAGE_CACHE_SHIFT;
	unsigned long npages = dir_pages(inode);
	unsigned chunk_mask = ~(ext2_chunk_size(inode)-1);
	unsigned char *types = NULL;
	int need_revalidate = filp->f_version != inode->i_version;

	if (pos > inode->i_size - EXT2_DIR_REC_LEN(1))
		return 0;

	if (EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_FILETYPE))
		types = ext2_filetype_table;

	for ( ; n < npages; n++, offset = 0) {
		char *kaddr, *limit;
		ext2_dirent *de;
		struct page *page = ext2_get_page(inode, n);

		if (IS_ERR(page)) {
			ext2_error(sb, __FUNCTION__,
				   "bad page in #%lu",
				   inode->i_ino);
			filp->f_pos += PAGE_CACHE_SIZE - offset;
			return PTR_ERR(page);
		}
		kaddr = page_address(page);
		if (unlikely(need_revalidate)) {
			if (offset) {
				offset = ext2_validate_entry(kaddr, offset, chunk_mask);
				filp->f_pos = (n<<PAGE_CACHE_SHIFT) + offset;
			}
			filp->f_version = inode->i_version;
			need_revalidate = 0;
		}
		de = (ext2_dirent *)(kaddr+offset);
		limit = kaddr + ext2_last_byte(inode, n) - EXT2_DIR_REC_LEN(1);
		for ( ;(char*)de <= limit; de = ext2_next_entry(de)) {
			if (de->rec_len == 0) {
				ext2_error(sb, __FUNCTION__,
					"zero-length directory entry");
				ext2_put_page(page);
				return -EIO;
			}
			if (de->inode) {
				int over;
				unsigned char d_type = DT_UNKNOWN;

				if (types && de->file_type < EXT2_FT_MAX)
					d_type = types[de->file_type];

				offset = (char *)de - kaddr;
				over = filldir(dirent, de->name, de->name_len,
						(n<<PAGE_CACHE_SHIFT) | offset,
						le32_to_cpu(de->inode), d_type);
				if (over) {
					ext2_put_page(page);
					return 0;
				}
			}
			filp->f_pos += ext2_rec_len_from_disk(de->rec_len);
		}
		ext2_put_page(page);
	}
	return 0;
}

/*
 *	ext2_find_entry()
 *
 * finds an entry in the specified directory with the wanted name. It
 * returns the page in which the entry was found, and the entry itself
 * (as a parameter - res_dir). Page is returned mapped and unlocked.
 * Entry is guaranteed to be valid.
 */
struct ext2_dir_entry_2 * ext2_find_entry (struct inode * dir,
			struct dentry *dentry, struct page ** res_page)
{
	const char *name = dentry->d_name.name;
	int namelen = dentry->d_name.len;
	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
	unsigned long start, n;
	unsigned long npages = dir_pages(dir);
	struct page *page = NULL;
	struct ext2_inode_info *ei = EXT2_I(dir);
	ext2_dirent * de;

	if (npages == 0)
		goto out;

	/* OFFSET_CACHE */
	*res_page = NULL;

	start = ei->i_dir_start_lookup;
	if (start >= npages)
		start = 0;
	n = start;
	do {
		char *kaddr;
		page = ext2_get_page(dir, n);
		if (!IS_ERR(page)) {
			kaddr = page_address(page);
			de = (ext2_dirent *) kaddr;
			kaddr += ext2_last_byte(dir, n) - reclen;
			while ((char *) de <= kaddr) {
				if (de->rec_len == 0) {
					ext2_error(dir->i_sb, __FUNCTION__,
						"zero-length directory entry");
					ext2_put_page(page);
					goto out;
				}
				if (ext2_match (namelen, name, de))
					goto found;
				de = ext2_next_entry(de);
			}
			ext2_put_page(page);
		}
		if (++n >= npages)
			n = 0;
		/* next page is past the blocks we've got */
		if (unlikely(n > (dir->i_blocks >> (PAGE_CACHE_SHIFT - 9)))) {
			ext2_error(dir->i_sb, __FUNCTION__,
				"dir %lu size %lld exceeds block count %llu",
				dir->i_ino, dir->i_size,
				(unsigned long long)dir->i_blocks);
			goto out;
		}
	} while (n != start);
out:
	return NULL;

found:
	*res_page = page;
	ei->i_dir_start_lookup = n;
	return de;
}

struct ext2_dir_entry_2 * ext2_dotdot (struct inode *dir, struct page **p)
{
	struct page *page = ext2_get_page(dir, 0);
	ext2_dirent *de = NULL;

	if (!IS_ERR(page)) {
		de = ext2_next_entry((ext2_dirent *) page_address(page));
		*p = page;
	}
	return de;
}

ino_t ext2_inode_by_name(struct inode * dir, struct dentry *dentry)
{
	ino_t res = 0;
	struct ext2_dir_entry_2 * de;
	struct page *page;
	
	de = ext2_find_entry (dir, dentry, &page);
	if (de) {
		res = le32_to_cpu(de->inode);
		ext2_put_page(page);
	}
	return res;
}

/* Releases the page */
void ext2_set_link(struct inode *dir, struct ext2_dir_entry_2 *de,
			struct page *page, struct inode *inode)
{
	loff_t pos = page_offset(page) +
			(char *) de - (char *) page_address(page);
	unsigned len = ext2_rec_len_from_disk(de->rec_len);
	int err;

	lock_page(page);
	err = __ext2_write_begin(NULL, page->mapping, pos, len,
				AOP_FLAG_UNINTERRUPTIBLE, &page, NULL);
	BUG_ON(err);
	de->inode = cpu_to_le32(inode->i_ino);
	ext2_set_de_type(de, inode);
	err = ext2_commit_chunk(page, pos, len);
	ext2_put_page(page);
	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
	mark_inode_dirty(dir);
}

/*
 *	Parent is locked.
 */
int ext2_add_link (struct dentry *dentry, struct inode *inode)
{
	struct inode *dir = dentry->d_parent->d_inode;
	const char *name = dentry->d_name.name;
	int namelen = dentry->d_name.len;
	unsigned chunk_size = ext2_chunk_size(dir);
	unsigned reclen = EXT2_DIR_REC_LEN(namelen);
	unsigned short rec_len, name_len;
	struct page *page = NULL;
	ext2_dirent * de;
	unsigned long npages = dir_pages(dir);
	unsigned long n;
	char *kaddr;
	loff_t pos;
	int err;

	/*
	 * We take care of directory expansion in the same loop.
	 * This code plays outside i_size, so it locks the page
	 * to protect that region.
	 */
	for (n = 0; n <= npages; n++) {
		char *dir_end;

		page = ext2_get_page(dir, n);
		err = PTR_ERR(page);
		if (IS_ERR(page))
			goto out;
		lock_page(page);
		kaddr = page_address(page);
		dir_end = kaddr + ext2_last_byte(dir, n);
		de = (ext2_dirent *)kaddr;
		kaddr += PAGE_CACHE_SIZE - reclen;
		while ((char *)de <= kaddr) {
			if ((char *)de == dir_end) {
				/* We hit i_size */
				name_len = 0;
				rec_len = chunk_size;
				de->rec_len = ext2_rec_len_to_disk(chunk_size);
				de->inode = 0;
				goto got_it;
			}
			if (de->rec_len == 0) {
				ext2_error(dir->i_sb, __FUNCTION__,
					"zero-length directory entry");
				err = -EIO;
				goto out_unlock;
			}
			err = -EEXIST;
			if (ext2_match (namelen, name, de))
				goto out_unlock;
			name_len = EXT2_DIR_REC_LEN(de->name_len);
			rec_len = ext2_rec_len_from_disk(de->rec_len);
			if (!de->inode && rec_len >= reclen)
				goto got_it;
			if (rec_len >= name_len + reclen)
				goto got_it;
			de = (ext2_dirent *) ((char *) de + rec_len);
		}
		unlock_page(page);
		ext2_put_page(page);
	}
	BUG();
	return -EINVAL;

got_it:
	pos = page_offset(page) +
		(char*)de - (char*)page_address(page);
	err = __ext2_write_begin(NULL, page->mapping, pos, rec_len, 0,
							&page, NULL);
	if (err)
		goto out_unlock;
	if (de->inode) {
		ext2_dirent *de1 = (ext2_dirent *) ((char *) de + name_len);
		de1->rec_len = ext2_rec_len_to_disk(rec_len - name_len);
		de->rec_len = ext2_rec_len_to_disk(name_len);
		de = de1;
	}
	de->name_len = namelen;
	memcpy(de->name, name, namelen);
	de->inode = cpu_to_le32(inode->i_ino);
	ext2_set_de_type (de, inode);
	err = ext2_commit_chunk(page, pos, rec_len);
	dir->i_mtime = dir->i_ctime = CURRENT_TIME_SEC;
	EXT2_I(dir)->i_flags &= ~EXT2_BTREE_FL;
	mark_inode_dirty(dir);
	/* OFFSET_CACHE */
out_put:
	ext2_put_page(page);
out:
	return err;
out_unlock:
	unlock_page(page);
	goto out_put;
}

/*
 * ext2_delete_entry deletes a directory entry by merging it with the
 * previous entry. Page is up-to-date. Releases the page.
 */
int ext2_delete_entry (struct ext2_dir_entry_2 * dir, struct page * page )
{
	struct address_space *mapping = page->mapping;
	struct inode *inode = mapping->host;
	char *kaddr = page_address(page);
	unsigned from = ((char*)dir - kaddr) & ~(ext2_chunk_size(inode)-1);
	unsigned to = ((char *)dir - kaddr) +
				ext2_rec_len_from_disk(dir->rec_len);
	loff_t pos;
	ext2_dirent * pde = NULL;
	ext2_dirent * de = (ext2_dirent *) (kaddr + from);
	int err;

	while ((char*)de < (char*)dir) {
		if (de->rec_len == 0) {
			ext2_error(inode->i_sb, __FUNCTION__,
				"zero-length directory entry");
			err = -EIO;
			goto out;
		}
		pde = de;
		de = ext2_next_entry(de);
	}
	if (pde)
		from = (char*)pde - (char*)page_address(page);
	pos = page_offset(page) + from;
	lock_page(page);
	err = __ext2_write_begin(NULL, page->mapping, pos, to - from, 0,
							&page, NULL);
	BUG_ON(err);
	if (pde)
		pde->rec_len = ext2_rec_len_to_disk(to - from);
	dir->inode = 0;
	err = ext2_commit_chunk(page, pos, to - from);
	inode->i_ctime = inode->i_mtime = CURRENT_TIME_SEC;
	EXT2_I(inode)->i_flags &= ~EXT2_BTREE_FL;
	mark_inode_dirty(inode);
out:
	ext2_put_page(page);
	return err;
}

/*
 * Set the first fragment of directory.
 */
int ext2_make_empty(struct inode *inode, struct inode *parent)
{
	struct address_space *mapping = inode->i_mapping;
	struct page *page = grab_cache_page(mapping, 0);
	unsigned chunk_size = ext2_chunk_size(inode);
	struct ext2_dir_entry_2 * de;
	int err;
	void *kaddr;

	if (!page)
		return -ENOMEM;

	err = __ext2_write_begin(NULL, page->mapping, 0, chunk_size, 0,
							&page, NULL);
	if (err) {
		unlock_page(page);
		goto fail;
	}
	kaddr = kmap_atomic(page, KM_USER0);
	memset(kaddr, 0, chunk_size);
	de = (struct ext2_dir_entry_2 *)kaddr;
	de->name_len = 1;
	de->rec_len = ext2_rec_len_to_disk(EXT2_DIR_REC_LEN(1));
	memcpy (de->name, ".\0\0", 4);
	de->inode = cpu_to_le32(inode->i_ino);
	ext2_set_de_type (de, inode);

	de = (struct ext2_dir_entry_2 *)(kaddr + EXT2_DIR_REC_LEN(1));
	de->name_len = 2;
	de->rec_len = ext2_rec_len_to_disk(chunk_size - EXT2_DIR_REC_LEN(1));
	de->inode = cpu_to_le32(parent->i_ino);
	memcpy (de->name, "..\0", 4);
	ext2_set_de_type (de, inode);
	kunmap_atomic(kaddr, KM_USER0);
	err = ext2_commit_chunk(page, 0, chunk_size);
fail:
	page_cache_release(page);
	return err;
}

/*
 * routine to check that the specified directory is empty (for rmdir)
 */
int ext2_empty_dir (struct inode * inode)
{
	struct page *page = NULL;
	unsigned long i, npages = dir_pages(inode);

	for (i = 0; i < npages; i++) {
		char *kaddr;
		ext2_dirent * de;
		page = ext2_get_page(inode, i);

		if (IS_ERR(page))
			continue;

		kaddr = page_address(page);
		de = (ext2_dirent *)kaddr;
		kaddr += ext2_last_byte(inode, i) - EXT2_DIR_REC_LEN(1);

		while ((char *)de <= kaddr) {
			if (de->rec_len == 0) {
				ext2_error(inode->i_sb, __FUNCTION__,
					"zero-length directory entry");
				printk("kaddr=%p, de=%p\n", kaddr, de);
				goto not_empty;
			}
			if (de->inode != 0) {
				/* check for . and .. */
				if (de->name[0] != '.')
					goto not_empty;
				if (de->name_len > 2)
					goto not_empty;
				if (de->name_len < 2) {
					if (de->inode !=
					    cpu_to_le32(inode->i_ino))
						goto not_empty;
				} else if (de->name[1] != '.')
					goto not_empty;
			}
			de = ext2_next_entry(de);
		}
		ext2_put_page(page);
	}
	return 1;

not_empty:
	ext2_put_page(page);
	return 0;
}

const struct file_operations ext2_dir_operations = {
	.llseek		= generic_file_llseek,
	.read		= generic_read_dir,
	.readdir	= ext2_readdir,
	.unlocked_ioctl = ext2_ioctl,
#ifdef CONFIG_COMPAT
	.compat_ioctl	= ext2_compat_ioctl,
#endif
	.fsync		= ext2_sync_file,
};