summaryrefslogtreecommitdiff
path: root/fs/fat/namei_vfat.c
blob: bf46a2d7dc50d3dba408b49360bc2177e7a829f5 (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
803
804
805
806
807
808
809
810
811
812
813
814
815
816
817
818
819
820
821
822
823
824
825
826
827
828
829
830
831
832
833
834
835
836
837
838
839
840
841
842
843
844
845
846
847
848
849
850
851
852
853
854
855
856
857
858
859
860
861
862
863
864
865
866
867
868
869
870
871
872
873
874
875
876
877
878
879
880
881
882
883
884
885
886
887
888
889
890
891
892
893
894
895
896
897
898
899
900
901
902
903
904
905
906
907
908
909
910
911
912
913
914
915
916
917
918
919
920
921
922
923
924
925
926
927
928
929
930
931
932
933
934
935
936
937
938
939
940
941
942
943
944
945
946
947
948
949
950
951
952
953
954
955
956
957
958
959
960
961
962
963
964
965
966
967
968
969
970
971
972
973
974
975
976
977
978
979
980
981
982
983
984
985
986
987
988
989
990
991
992
993
994
995
996
997
998
999
1000
1001
1002
1003
1004
1005
1006
1007
1008
1009
1010
1011
1012
1013
1014
1015
1016
1017
1018
1019
1020
1021
1022
1023
1024
1025
1026
1027
1028
1029
1030
1031
1032
1033
1034
1035
1036
1037
1038
1039
1040
1041
1042
1043
1044
1045
1046
1047
1048
1049
1050
1051
1052
1053
1054
1055
1056
1057
1058
1059
1060
1061
1062
1063
1064
1065
1066
1067
1068
1069
1070
1071
1072
1073
1074
1075
1076
1077
1078
1079
1080
1081
1082
1083
1084
1085
1086
1087
1088
1089
1090
1091
1092
1093
/*
 *  linux/fs/vfat/namei.c
 *
 *  Written 1992,1993 by Werner Almesberger
 *
 *  Windows95/Windows NT compatible extended MSDOS filesystem
 *    by Gordon Chaffee Copyright (C) 1995.  Send bug reports for the
 *    VFAT filesystem to <chaffee@cs.berkeley.edu>.  Specify
 *    what file operation caused you trouble and if you can duplicate
 *    the problem, send a script that demonstrates it.
 *
 *  Short name translation 1999, 2001 by Wolfram Pienkoss <wp@bszh.de>
 *
 *  Support Multibyte characters and cleanup by
 *				OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
 */

#include <linux/module.h>
#include <linux/ctype.h>
#include <linux/slab.h>
#include <linux/namei.h>
#include "fat.h"

/*
 * If new entry was created in the parent, it could create the 8.3
 * alias (the shortname of logname).  So, the parent may have the
 * negative-dentry which matches the created 8.3 alias.
 *
 * If it happened, the negative dentry isn't actually negative
 * anymore.  So, drop it.
 */
static int vfat_revalidate_shortname(struct dentry *dentry)
{
	int ret = 1;
	spin_lock(&dentry->d_lock);
	if (dentry->d_time != d_inode(dentry->d_parent)->i_version)
		ret = 0;
	spin_unlock(&dentry->d_lock);
	return ret;
}

static int vfat_revalidate(struct dentry *dentry, unsigned int flags)
{
	if (flags & LOOKUP_RCU)
		return -ECHILD;

	/* This is not negative dentry. Always valid. */
	if (d_really_is_positive(dentry))
		return 1;
	return vfat_revalidate_shortname(dentry);
}

static int vfat_revalidate_ci(struct dentry *dentry, unsigned int flags)
{
	if (flags & LOOKUP_RCU)
		return -ECHILD;

	/*
	 * This is not negative dentry. Always valid.
	 *
	 * Note, rename() to existing directory entry will have ->d_inode,
	 * and will use existing name which isn't specified name by user.
	 *
	 * We may be able to drop this positive dentry here. But dropping
	 * positive dentry isn't good idea. So it's unsupported like
	 * rename("filename", "FILENAME") for now.
	 */
	if (d_really_is_positive(dentry))
		return 1;

	/*
	 * This may be nfsd (or something), anyway, we can't see the
	 * intent of this. So, since this can be for creation, drop it.
	 */
	if (!flags)
		return 0;

	/*
	 * Drop the negative dentry, in order to make sure to use the
	 * case sensitive name which is specified by user if this is
	 * for creation.
	 */
	if (flags & (LOOKUP_CREATE | LOOKUP_RENAME_TARGET))
		return 0;

	return vfat_revalidate_shortname(dentry);
}

/* returns the length of a struct qstr, ignoring trailing dots */
static unsigned int __vfat_striptail_len(unsigned int len, const char *name)
{
	while (len && name[len - 1] == '.')
		len--;
	return len;
}

static unsigned int vfat_striptail_len(const struct qstr *qstr)
{
	return __vfat_striptail_len(qstr->len, qstr->name);
}

/*
 * Compute the hash for the vfat name corresponding to the dentry.
 * Note: if the name is invalid, we leave the hash code unchanged so
 * that the existing dentry can be used. The vfat fs routines will
 * return ENOENT or EINVAL as appropriate.
 */
static int vfat_hash(const struct dentry *dentry, struct qstr *qstr)
{
	qstr->hash = full_name_hash(dentry, qstr->name, vfat_striptail_len(qstr));
	return 0;
}

/*
 * Compute the hash for the vfat name corresponding to the dentry.
 * Note: if the name is invalid, we leave the hash code unchanged so
 * that the existing dentry can be used. The vfat fs routines will
 * return ENOENT or EINVAL as appropriate.
 */
static int vfat_hashi(const struct dentry *dentry, struct qstr *qstr)
{
	struct nls_table *t = MSDOS_SB(dentry->d_sb)->nls_io;
	const unsigned char *name;
	unsigned int len;
	unsigned long hash;

	name = qstr->name;
	len = vfat_striptail_len(qstr);

	hash = init_name_hash(dentry);
	while (len--)
		hash = partial_name_hash(nls_tolower(t, *name++), hash);
	qstr->hash = end_name_hash(hash);

	return 0;
}

/*
 * Case insensitive compare of two vfat names.
 */
static int vfat_cmpi(const struct dentry *dentry,
		unsigned int len, const char *str, const struct qstr *name)
{
	struct nls_table *t = MSDOS_SB(dentry->d_sb)->nls_io;
	unsigned int alen, blen;

	/* A filename cannot end in '.' or we treat it like it has none */
	alen = vfat_striptail_len(name);
	blen = __vfat_striptail_len(len, str);
	if (alen == blen) {
		if (nls_strnicmp(t, name->name, str, alen) == 0)
			return 0;
	}
	return 1;
}

/*
 * Case sensitive compare of two vfat names.
 */
static int vfat_cmp(const struct dentry *dentry,
		unsigned int len, const char *str, const struct qstr *name)
{
	unsigned int alen, blen;

	/* A filename cannot end in '.' or we treat it like it has none */
	alen = vfat_striptail_len(name);
	blen = __vfat_striptail_len(len, str);
	if (alen == blen) {
		if (strncmp(name->name, str, alen) == 0)
			return 0;
	}
	return 1;
}

static const struct dentry_operations vfat_ci_dentry_ops = {
	.d_revalidate	= vfat_revalidate_ci,
	.d_hash		= vfat_hashi,
	.d_compare	= vfat_cmpi,
};

static const struct dentry_operations vfat_dentry_ops = {
	.d_revalidate	= vfat_revalidate,
	.d_hash		= vfat_hash,
	.d_compare	= vfat_cmp,
};

/* Characters that are undesirable in an MS-DOS file name */

static inline wchar_t vfat_bad_char(wchar_t w)
{
	return (w < 0x0020)
	    || (w == '*') || (w == '?') || (w == '<') || (w == '>')
	    || (w == '|') || (w == '"') || (w == ':') || (w == '/')
	    || (w == '\\');
}

static inline wchar_t vfat_replace_char(wchar_t w)
{
	return (w == '[') || (w == ']') || (w == ';') || (w == ',')
	    || (w == '+') || (w == '=');
}

static wchar_t vfat_skip_char(wchar_t w)
{
	return (w == '.') || (w == ' ');
}

static inline int vfat_is_used_badchars(const wchar_t *s, int len)
{
	int i;

	for (i = 0; i < len; i++)
		if (vfat_bad_char(s[i]))
			return -EINVAL;

	if (s[i - 1] == ' ') /* last character cannot be space */
		return -EINVAL;

	return 0;
}

static int vfat_find_form(struct inode *dir, unsigned char *name)
{
	struct fat_slot_info sinfo;
	int err = fat_scan(dir, name, &sinfo);
	if (err)
		return -ENOENT;
	brelse(sinfo.bh);
	return 0;
}

/*
 * 1) Valid characters for the 8.3 format alias are any combination of
 * letters, uppercase alphabets, digits, any of the
 * following special characters:
 *     $ % ' ` - @ { } ~ ! # ( ) & _ ^
 * In this case Longfilename is not stored in disk.
 *
 * WinNT's Extension:
 * File name and extension name is contain uppercase/lowercase
 * only. And it is expressed by CASE_LOWER_BASE and CASE_LOWER_EXT.
 *
 * 2) File name is 8.3 format, but it contain the uppercase and
 * lowercase char, muliti bytes char, etc. In this case numtail is not
 * added, but Longfilename is stored.
 *
 * 3) When the one except for the above, or the following special
 * character are contained:
 *        .   [ ] ; , + =
 * numtail is added, and Longfilename must be stored in disk .
 */
struct shortname_info {
	unsigned char lower:1,
		      upper:1,
		      valid:1;
};
#define INIT_SHORTNAME_INFO(x)	do {		\
	(x)->lower = 1;				\
	(x)->upper = 1;				\
	(x)->valid = 1;				\
} while (0)

static inline int to_shortname_char(struct nls_table *nls,
				    unsigned char *buf, int buf_size,
				    wchar_t *src, struct shortname_info *info)
{
	int len;

	if (vfat_skip_char(*src)) {
		info->valid = 0;
		return 0;
	}
	if (vfat_replace_char(*src)) {
		info->valid = 0;
		buf[0] = '_';
		return 1;
	}

	len = nls->uni2char(*src, buf, buf_size);
	if (len <= 0) {
		info->valid = 0;
		buf[0] = '_';
		len = 1;
	} else if (len == 1) {
		unsigned char prev = buf[0];

		if (buf[0] >= 0x7F) {
			info->lower = 0;
			info->upper = 0;
		}

		buf[0] = nls_toupper(nls, buf[0]);
		if (isalpha(buf[0])) {
			if (buf[0] == prev)
				info->lower = 0;
			else
				info->upper = 0;
		}
	} else {
		info->lower = 0;
		info->upper = 0;
	}

	return len;
}

/*
 * Given a valid longname, create a unique shortname.  Make sure the
 * shortname does not exist
 * Returns negative number on error, 0 for a normal
 * return, and 1 for valid shortname
 */
static int vfat_create_shortname(struct inode *dir, struct nls_table *nls,
				 wchar_t *uname, int ulen,
				 unsigned char *name_res, unsigned char *lcase)
{
	struct fat_mount_options *opts = &MSDOS_SB(dir->i_sb)->options;
	wchar_t *ip, *ext_start, *end, *name_start;
	unsigned char base[9], ext[4], buf[5], *p;
	unsigned char charbuf[NLS_MAX_CHARSET_SIZE];
	int chl, chi;
	int sz = 0, extlen, baselen, i, numtail_baselen, numtail2_baselen;
	int is_shortname;
	struct shortname_info base_info, ext_info;

	is_shortname = 1;
	INIT_SHORTNAME_INFO(&base_info);
	INIT_SHORTNAME_INFO(&ext_info);

	/* Now, we need to create a shortname from the long name */
	ext_start = end = &uname[ulen];
	while (--ext_start >= uname) {
		if (*ext_start == 0x002E) {	/* is `.' */
			if (ext_start == end - 1) {
				sz = ulen;
				ext_start = NULL;
			}
			break;
		}
	}

	if (ext_start == uname - 1) {
		sz = ulen;
		ext_start = NULL;
	} else if (ext_start) {
		/*
		 * Names which start with a dot could be just
		 * an extension eg. "...test".  In this case Win95
		 * uses the extension as the name and sets no extension.
		 */
		name_start = &uname[0];
		while (name_start < ext_start) {
			if (!vfat_skip_char(*name_start))
				break;
			name_start++;
		}
		if (name_start != ext_start) {
			sz = ext_start - uname;
			ext_start++;
		} else {
			sz = ulen;
			ext_start = NULL;
		}
	}

	numtail_baselen = 6;
	numtail2_baselen = 2;
	for (baselen = i = 0, p = base, ip = uname; i < sz; i++, ip++) {
		chl = to_shortname_char(nls, charbuf, sizeof(charbuf),
					ip, &base_info);
		if (chl == 0)
			continue;

		if (baselen < 2 && (baselen + chl) > 2)
			numtail2_baselen = baselen;
		if (baselen < 6 && (baselen + chl) > 6)
			numtail_baselen = baselen;
		for (chi = 0; chi < chl; chi++) {
			*p++ = charbuf[chi];
			baselen++;
			if (baselen >= 8)
				break;
		}
		if (baselen >= 8) {
			if ((chi < chl - 1) || (ip + 1) - uname < sz)
				is_shortname = 0;
			break;
		}
	}
	if (baselen == 0) {
		return -EINVAL;
	}

	extlen = 0;
	if (ext_start) {
		for (p = ext, ip = ext_start; extlen < 3 && ip < end; ip++) {
			chl = to_shortname_char(nls, charbuf, sizeof(charbuf),
						ip, &ext_info);
			if (chl == 0)
				continue;

			if ((extlen + chl) > 3) {
				is_shortname = 0;
				break;
			}
			for (chi = 0; chi < chl; chi++) {
				*p++ = charbuf[chi];
				extlen++;
			}
			if (extlen >= 3) {
				if (ip + 1 != end)
					is_shortname = 0;
				break;
			}
		}
	}
	ext[extlen] = '\0';
	base[baselen] = '\0';

	/* Yes, it can happen. ".\xe5" would do it. */
	if (base[0] == DELETED_FLAG)
		base[0] = 0x05;

	/* OK, at this point we know that base is not longer than 8 symbols,
	 * ext is not longer than 3, base is nonempty, both don't contain
	 * any bad symbols (lowercase transformed to uppercase).
	 */

	memset(name_res, ' ', MSDOS_NAME);
	memcpy(name_res, base, baselen);
	memcpy(name_res + 8, ext, extlen);
	*lcase = 0;
	if (is_shortname && base_info.valid && ext_info.valid) {
		if (vfat_find_form(dir, name_res) == 0)
			return -EEXIST;

		if (opts->shortname & VFAT_SFN_CREATE_WIN95) {
			return (base_info.upper && ext_info.upper);
		} else if (opts->shortname & VFAT_SFN_CREATE_WINNT) {
			if ((base_info.upper || base_info.lower) &&
			    (ext_info.upper || ext_info.lower)) {
				if (!base_info.upper && base_info.lower)
					*lcase |= CASE_LOWER_BASE;
				if (!ext_info.upper && ext_info.lower)
					*lcase |= CASE_LOWER_EXT;
				return 1;
			}
			return 0;
		} else {
			BUG();
		}
	}

	if (opts->numtail == 0)
		if (vfat_find_form(dir, name_res) < 0)
			return 0;

	/*
	 * Try to find a unique extension.  This used to
	 * iterate through all possibilities sequentially,
	 * but that gave extremely bad performance.  Windows
	 * only tries a few cases before using random
	 * values for part of the base.
	 */

	if (baselen > 6) {
		baselen = numtail_baselen;
		name_res[7] = ' ';
	}
	name_res[baselen] = '~';
	for (i = 1; i < 10; i++) {
		name_res[baselen + 1] = i + '0';
		if (vfat_find_form(dir, name_res) < 0)
			return 0;
	}

	i = jiffies;
	sz = (jiffies >> 16) & 0x7;
	if (baselen > 2) {
		baselen = numtail2_baselen;
		name_res[7] = ' ';
	}
	name_res[baselen + 4] = '~';
	name_res[baselen + 5] = '1' + sz;
	while (1) {
		snprintf(buf, sizeof(buf), "%04X", i & 0xffff);
		memcpy(&name_res[baselen], buf, 4);
		if (vfat_find_form(dir, name_res) < 0)
			break;
		i -= 11;
	}
	return 0;
}

/* Translate a string, including coded sequences into Unicode */
static int
xlate_to_uni(const unsigned char *name, int len, unsigned char *outname,
	     int *longlen, int *outlen, int escape, int utf8,
	     struct nls_table *nls)
{
	const unsigned char *ip;
	unsigned char nc;
	unsigned char *op;
	unsigned int ec;
	int i, k, fill;
	int charlen;

	if (utf8) {
		*outlen = utf8s_to_utf16s(name, len, UTF16_HOST_ENDIAN,
				(wchar_t *) outname, FAT_LFN_LEN + 2);
		if (*outlen < 0)
			return *outlen;
		else if (*outlen > FAT_LFN_LEN)
			return -ENAMETOOLONG;

		op = &outname[*outlen * sizeof(wchar_t)];
	} else {
		for (i = 0, ip = name, op = outname, *outlen = 0;
			 i < len && *outlen < FAT_LFN_LEN;
			 *outlen += 1) {
			if (escape && (*ip == ':')) {
				if (i > len - 5)
					return -EINVAL;
				ec = 0;
				for (k = 1; k < 5; k++) {
					nc = ip[k];
					ec <<= 4;
					if (nc >= '0' && nc <= '9') {
						ec |= nc - '0';
						continue;
					}
					if (nc >= 'a' && nc <= 'f') {
						ec |= nc - ('a' - 10);
						continue;
					}
					if (nc >= 'A' && nc <= 'F') {
						ec |= nc - ('A' - 10);
						continue;
					}
					return -EINVAL;
				}
				*op++ = ec & 0xFF;
				*op++ = ec >> 8;
				ip += 5;
				i += 5;
			} else {
				charlen = nls->char2uni(ip, len - i,
									(wchar_t *)op);
				if (charlen < 0)
					return -EINVAL;
				ip += charlen;
				i += charlen;
				op += 2;
			}
		}
		if (i < len)
			return -ENAMETOOLONG;
	}

	*longlen = *outlen;
	if (*outlen % 13) {
		*op++ = 0;
		*op++ = 0;
		*outlen += 1;
		if (*outlen % 13) {
			fill = 13 - (*outlen % 13);
			for (i = 0; i < fill; i++) {
				*op++ = 0xff;
				*op++ = 0xff;
			}
			*outlen += fill;
		}
	}

	return 0;
}

static int vfat_build_slots(struct inode *dir, const unsigned char *name,
			    int len, int is_dir, int cluster,
			    struct timespec *ts,
			    struct msdos_dir_slot *slots, int *nr_slots)
{
	struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb);
	struct fat_mount_options *opts = &sbi->options;
	struct msdos_dir_slot *ps;
	struct msdos_dir_entry *de;
	unsigned char cksum, lcase;
	unsigned char msdos_name[MSDOS_NAME];
	wchar_t *uname;
	__le16 time, date;
	u8 time_cs;
	int err, ulen, usize, i;
	loff_t offset;

	*nr_slots = 0;

	uname = __getname();
	if (!uname)
		return -ENOMEM;

	err = xlate_to_uni(name, len, (unsigned char *)uname, &ulen, &usize,
			   opts->unicode_xlate, opts->utf8, sbi->nls_io);
	if (err)
		goto out_free;

	err = vfat_is_used_badchars(uname, ulen);
	if (err)
		goto out_free;

	err = vfat_create_shortname(dir, sbi->nls_disk, uname, ulen,
				    msdos_name, &lcase);
	if (err < 0)
		goto out_free;
	else if (err == 1) {
		de = (struct msdos_dir_entry *)slots;
		err = 0;
		goto shortname;
	}

	/* build the entry of long file name */
	cksum = fat_checksum(msdos_name);

	*nr_slots = usize / 13;
	for (ps = slots, i = *nr_slots; i > 0; i--, ps++) {
		ps->id = i;
		ps->attr = ATTR_EXT;
		ps->reserved = 0;
		ps->alias_checksum = cksum;
		ps->start = 0;
		offset = (i - 1) * 13;
		fatwchar_to16(ps->name0_4, uname + offset, 5);
		fatwchar_to16(ps->name5_10, uname + offset + 5, 6);
		fatwchar_to16(ps->name11_12, uname + offset + 11, 2);
	}
	slots[0].id |= 0x40;
	de = (struct msdos_dir_entry *)ps;

shortname:
	/* build the entry of 8.3 alias name */
	(*nr_slots)++;
	memcpy(de->name, msdos_name, MSDOS_NAME);
	de->attr = is_dir ? ATTR_DIR : ATTR_ARCH;
	de->lcase = lcase;
	fat_time_unix2fat(sbi, ts, &time, &date, &time_cs);
	de->time = de->ctime = time;
	de->date = de->cdate = de->adate = date;
	de->ctime_cs = time_cs;
	fat_set_start(de, cluster);
	de->size = 0;
out_free:
	__putname(uname);
	return err;
}

static int vfat_add_entry(struct inode *dir, const struct qstr *qname,
			  int is_dir, int cluster, struct timespec *ts,
			  struct fat_slot_info *sinfo)
{
	struct msdos_dir_slot *slots;
	unsigned int len;
	int err, nr_slots;

	len = vfat_striptail_len(qname);
	if (len == 0)
		return -ENOENT;

	slots = kmalloc(sizeof(*slots) * MSDOS_SLOTS, GFP_NOFS);
	if (slots == NULL)
		return -ENOMEM;

	err = vfat_build_slots(dir, qname->name, len, is_dir, cluster, ts,
			       slots, &nr_slots);
	if (err)
		goto cleanup;

	err = fat_add_entries(dir, slots, nr_slots, sinfo);
	if (err)
		goto cleanup;

	/* update timestamp */
	dir->i_ctime = dir->i_mtime = dir->i_atime = *ts;
	if (IS_DIRSYNC(dir))
		(void)fat_sync_inode(dir);
	else
		mark_inode_dirty(dir);
cleanup:
	kfree(slots);
	return err;
}

static int vfat_find(struct inode *dir, const struct qstr *qname,
		     struct fat_slot_info *sinfo)
{
	unsigned int len = vfat_striptail_len(qname);
	if (len == 0)
		return -ENOENT;
	return fat_search_long(dir, qname->name, len, sinfo);
}

/*
 * (nfsd's) anonymous disconnected dentry?
 * NOTE: !IS_ROOT() is not anonymous (I.e. d_splice_alias() did the job).
 */
static int vfat_d_anon_disconn(struct dentry *dentry)
{
	return IS_ROOT(dentry) && (dentry->d_flags & DCACHE_DISCONNECTED);
}

static struct dentry *vfat_lookup(struct inode *dir, struct dentry *dentry,
				  unsigned int flags)
{
	struct super_block *sb = dir->i_sb;
	struct fat_slot_info sinfo;
	struct inode *inode;
	struct dentry *alias;
	int err;

	mutex_lock(&MSDOS_SB(sb)->s_lock);

	err = vfat_find(dir, &dentry->d_name, &sinfo);
	if (err) {
		if (err == -ENOENT) {
			inode = NULL;
			goto out;
		}
		goto error;
	}

	inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
	brelse(sinfo.bh);
	if (IS_ERR(inode)) {
		err = PTR_ERR(inode);
		goto error;
	}

	alias = d_find_alias(inode);
	/*
	 * Checking "alias->d_parent == dentry->d_parent" to make sure
	 * FS is not corrupted (especially double linked dir).
	 */
	if (alias && alias->d_parent == dentry->d_parent &&
	    !vfat_d_anon_disconn(alias)) {
		/*
		 * This inode has non anonymous-DCACHE_DISCONNECTED
		 * dentry. This means, the user did ->lookup() by an
		 * another name (longname vs 8.3 alias of it) in past.
		 *
		 * Switch to new one for reason of locality if possible.
		 */
		BUG_ON(d_unhashed(alias));
		if (!S_ISDIR(inode->i_mode))
			d_move(alias, dentry);
		iput(inode);
		mutex_unlock(&MSDOS_SB(sb)->s_lock);
		return alias;
	} else
		dput(alias);

out:
	mutex_unlock(&MSDOS_SB(sb)->s_lock);
	if (!inode)
		dentry->d_time = dir->i_version;
	return d_splice_alias(inode, dentry);
error:
	mutex_unlock(&MSDOS_SB(sb)->s_lock);
	return ERR_PTR(err);
}

static int vfat_create(struct inode *dir, struct dentry *dentry, umode_t mode,
		       bool excl)
{
	struct super_block *sb = dir->i_sb;
	struct inode *inode;
	struct fat_slot_info sinfo;
	struct timespec ts;
	int err;

	mutex_lock(&MSDOS_SB(sb)->s_lock);

	ts = current_time(dir);
	err = vfat_add_entry(dir, &dentry->d_name, 0, 0, &ts, &sinfo);
	if (err)
		goto out;
	dir->i_version++;

	inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
	brelse(sinfo.bh);
	if (IS_ERR(inode)) {
		err = PTR_ERR(inode);
		goto out;
	}
	inode->i_version++;
	inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
	/* timestamp is already written, so mark_inode_dirty() is unneeded. */

	d_instantiate(dentry, inode);
out:
	mutex_unlock(&MSDOS_SB(sb)->s_lock);
	return err;
}

static int vfat_rmdir(struct inode *dir, struct dentry *dentry)
{
	struct inode *inode = d_inode(dentry);
	struct super_block *sb = dir->i_sb;
	struct fat_slot_info sinfo;
	int err;

	mutex_lock(&MSDOS_SB(sb)->s_lock);

	err = fat_dir_empty(inode);
	if (err)
		goto out;
	err = vfat_find(dir, &dentry->d_name, &sinfo);
	if (err)
		goto out;

	err = fat_remove_entries(dir, &sinfo);	/* and releases bh */
	if (err)
		goto out;
	drop_nlink(dir);

	clear_nlink(inode);
	inode->i_mtime = inode->i_atime = current_time(inode);
	fat_detach(inode);
	dentry->d_time = dir->i_version;
out:
	mutex_unlock(&MSDOS_SB(sb)->s_lock);

	return err;
}

static int vfat_unlink(struct inode *dir, struct dentry *dentry)
{
	struct inode *inode = d_inode(dentry);
	struct super_block *sb = dir->i_sb;
	struct fat_slot_info sinfo;
	int err;

	mutex_lock(&MSDOS_SB(sb)->s_lock);

	err = vfat_find(dir, &dentry->d_name, &sinfo);
	if (err)
		goto out;

	err = fat_remove_entries(dir, &sinfo);	/* and releases bh */
	if (err)
		goto out;
	clear_nlink(inode);
	inode->i_mtime = inode->i_atime = current_time(inode);
	fat_detach(inode);
	dentry->d_time = dir->i_version;
out:
	mutex_unlock(&MSDOS_SB(sb)->s_lock);

	return err;
}

static int vfat_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
{
	struct super_block *sb = dir->i_sb;
	struct inode *inode;
	struct fat_slot_info sinfo;
	struct timespec ts;
	int err, cluster;

	mutex_lock(&MSDOS_SB(sb)->s_lock);

	ts = current_time(dir);
	cluster = fat_alloc_new_dir(dir, &ts);
	if (cluster < 0) {
		err = cluster;
		goto out;
	}
	err = vfat_add_entry(dir, &dentry->d_name, 1, cluster, &ts, &sinfo);
	if (err)
		goto out_free;
	dir->i_version++;
	inc_nlink(dir);

	inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
	brelse(sinfo.bh);
	if (IS_ERR(inode)) {
		err = PTR_ERR(inode);
		/* the directory was completed, just return a error */
		goto out;
	}
	inode->i_version++;
	set_nlink(inode, 2);
	inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
	/* timestamp is already written, so mark_inode_dirty() is unneeded. */

	d_instantiate(dentry, inode);

	mutex_unlock(&MSDOS_SB(sb)->s_lock);
	return 0;

out_free:
	fat_free_clusters(dir, cluster);
out:
	mutex_unlock(&MSDOS_SB(sb)->s_lock);
	return err;
}

static int vfat_rename(struct inode *old_dir, struct dentry *old_dentry,
		       struct inode *new_dir, struct dentry *new_dentry,
		       unsigned int flags)
{
	struct buffer_head *dotdot_bh;
	struct msdos_dir_entry *dotdot_de;
	struct inode *old_inode, *new_inode;
	struct fat_slot_info old_sinfo, sinfo;
	struct timespec ts;
	loff_t new_i_pos;
	int err, is_dir, update_dotdot, corrupt = 0;
	struct super_block *sb = old_dir->i_sb;

	if (flags & ~RENAME_NOREPLACE)
		return -EINVAL;

	old_sinfo.bh = sinfo.bh = dotdot_bh = NULL;
	old_inode = d_inode(old_dentry);
	new_inode = d_inode(new_dentry);
	mutex_lock(&MSDOS_SB(sb)->s_lock);
	err = vfat_find(old_dir, &old_dentry->d_name, &old_sinfo);
	if (err)
		goto out;

	is_dir = S_ISDIR(old_inode->i_mode);
	update_dotdot = (is_dir && old_dir != new_dir);
	if (update_dotdot) {
		if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de)) {
			err = -EIO;
			goto out;
		}
	}

	ts = current_time(old_dir);
	if (new_inode) {
		if (is_dir) {
			err = fat_dir_empty(new_inode);
			if (err)
				goto out;
		}
		new_i_pos = MSDOS_I(new_inode)->i_pos;
		fat_detach(new_inode);
	} else {
		err = vfat_add_entry(new_dir, &new_dentry->d_name, is_dir, 0,
				     &ts, &sinfo);
		if (err)
			goto out;
		new_i_pos = sinfo.i_pos;
	}
	new_dir->i_version++;

	fat_detach(old_inode);
	fat_attach(old_inode, new_i_pos);
	if (IS_DIRSYNC(new_dir)) {
		err = fat_sync_inode(old_inode);
		if (err)
			goto error_inode;
	} else
		mark_inode_dirty(old_inode);

	if (update_dotdot) {
		fat_set_start(dotdot_de, MSDOS_I(new_dir)->i_logstart);
		mark_buffer_dirty_inode(dotdot_bh, old_inode);
		if (IS_DIRSYNC(new_dir)) {
			err = sync_dirty_buffer(dotdot_bh);
			if (err)
				goto error_dotdot;
		}
		drop_nlink(old_dir);
		if (!new_inode)
 			inc_nlink(new_dir);
	}

	err = fat_remove_entries(old_dir, &old_sinfo);	/* and releases bh */
	old_sinfo.bh = NULL;
	if (err)
		goto error_dotdot;
	old_dir->i_version++;
	old_dir->i_ctime = old_dir->i_mtime = ts;
	if (IS_DIRSYNC(old_dir))
		(void)fat_sync_inode(old_dir);
	else
		mark_inode_dirty(old_dir);

	if (new_inode) {
		drop_nlink(new_inode);
		if (is_dir)
			drop_nlink(new_inode);
		new_inode->i_ctime = ts;
	}
out:
	brelse(sinfo.bh);
	brelse(dotdot_bh);
	brelse(old_sinfo.bh);
	mutex_unlock(&MSDOS_SB(sb)->s_lock);

	return err;

error_dotdot:
	/* data cluster is shared, serious corruption */
	corrupt = 1;

	if (update_dotdot) {
		fat_set_start(dotdot_de, MSDOS_I(old_dir)->i_logstart);
		mark_buffer_dirty_inode(dotdot_bh, old_inode);
		corrupt |= sync_dirty_buffer(dotdot_bh);
	}
error_inode:
	fat_detach(old_inode);
	fat_attach(old_inode, old_sinfo.i_pos);
	if (new_inode) {
		fat_attach(new_inode, new_i_pos);
		if (corrupt)
			corrupt |= fat_sync_inode(new_inode);
	} else {
		/*
		 * If new entry was not sharing the data cluster, it
		 * shouldn't be serious corruption.
		 */
		int err2 = fat_remove_entries(new_dir, &sinfo);
		if (corrupt)
			corrupt |= err2;
		sinfo.bh = NULL;
	}
	if (corrupt < 0) {
		fat_fs_error(new_dir->i_sb,
			     "%s: Filesystem corrupted (i_pos %lld)",
			     __func__, sinfo.i_pos);
	}
	goto out;
}

static const struct inode_operations vfat_dir_inode_operations = {
	.create		= vfat_create,
	.lookup		= vfat_lookup,
	.unlink		= vfat_unlink,
	.mkdir		= vfat_mkdir,
	.rmdir		= vfat_rmdir,
	.rename		= vfat_rename,
	.setattr	= fat_setattr,
	.getattr	= fat_getattr,
};

static void setup(struct super_block *sb)
{
	MSDOS_SB(sb)->dir_ops = &vfat_dir_inode_operations;
	if (MSDOS_SB(sb)->options.name_check != 's')
		sb->s_d_op = &vfat_ci_dentry_ops;
	else
		sb->s_d_op = &vfat_dentry_ops;
}

static int vfat_fill_super(struct super_block *sb, void *data, int silent)
{
	return fat_fill_super(sb, data, silent, 1, setup);
}

static struct dentry *vfat_mount(struct file_system_type *fs_type,
		       int flags, const char *dev_name,
		       void *data)
{
	return mount_bdev(fs_type, flags, dev_name, data, vfat_fill_super);
}

static struct file_system_type vfat_fs_type = {
	.owner		= THIS_MODULE,
	.name		= "vfat",
	.mount		= vfat_mount,
	.kill_sb	= kill_block_super,
	.fs_flags	= FS_REQUIRES_DEV,
};
MODULE_ALIAS_FS("vfat");

static int __init init_vfat_fs(void)
{
	return register_filesystem(&vfat_fs_type);
}

static void __exit exit_vfat_fs(void)
{
	unregister_filesystem(&vfat_fs_type);
}

MODULE_LICENSE("GPL");
MODULE_DESCRIPTION("VFAT filesystem support");
MODULE_AUTHOR("Gordon Chaffee");

module_init(init_vfat_fs)
module_exit(exit_vfat_fs)