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TOMOYO Linux Cross Reference
Linux/fs/fat/namei_vfat.c

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  1 /*
  2  *  linux/fs/vfat/namei.c
  3  *
  4  *  Written 1992,1993 by Werner Almesberger
  5  *
  6  *  Windows95/Windows NT compatible extended MSDOS filesystem
  7  *    by Gordon Chaffee Copyright (C) 1995.  Send bug reports for the
  8  *    VFAT filesystem to <chaffee@cs.berkeley.edu>.  Specify
  9  *    what file operation caused you trouble and if you can duplicate
 10  *    the problem, send a script that demonstrates it.
 11  *
 12  *  Short name translation 1999, 2001 by Wolfram Pienkoss <wp@bszh.de>
 13  *
 14  *  Support Multibyte characters and cleanup by
 15  *                              OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
 16  */
 17 
 18 #include <linux/module.h>
 19 #include <linux/jiffies.h>
 20 #include <linux/ctype.h>
 21 #include <linux/slab.h>
 22 #include <linux/buffer_head.h>
 23 #include <linux/namei.h>
 24 #include "fat.h"
 25 
 26 /*
 27  * If new entry was created in the parent, it could create the 8.3
 28  * alias (the shortname of logname).  So, the parent may have the
 29  * negative-dentry which matches the created 8.3 alias.
 30  *
 31  * If it happened, the negative dentry isn't actually negative
 32  * anymore.  So, drop it.
 33  */
 34 static int vfat_revalidate_shortname(struct dentry *dentry)
 35 {
 36         int ret = 1;
 37         spin_lock(&dentry->d_lock);
 38         if (dentry->d_time != dentry->d_parent->d_inode->i_version)
 39                 ret = 0;
 40         spin_unlock(&dentry->d_lock);
 41         return ret;
 42 }
 43 
 44 static int vfat_revalidate(struct dentry *dentry, unsigned int flags)
 45 {
 46         if (flags & LOOKUP_RCU)
 47                 return -ECHILD;
 48 
 49         /* This is not negative dentry. Always valid. */
 50         if (dentry->d_inode)
 51                 return 1;
 52         return vfat_revalidate_shortname(dentry);
 53 }
 54 
 55 static int vfat_revalidate_ci(struct dentry *dentry, unsigned int flags)
 56 {
 57         if (flags & LOOKUP_RCU)
 58                 return -ECHILD;
 59 
 60         /*
 61          * This is not negative dentry. Always valid.
 62          *
 63          * Note, rename() to existing directory entry will have ->d_inode,
 64          * and will use existing name which isn't specified name by user.
 65          *
 66          * We may be able to drop this positive dentry here. But dropping
 67          * positive dentry isn't good idea. So it's unsupported like
 68          * rename("filename", "FILENAME") for now.
 69          */
 70         if (dentry->d_inode)
 71                 return 1;
 72 
 73         /*
 74          * This may be nfsd (or something), anyway, we can't see the
 75          * intent of this. So, since this can be for creation, drop it.
 76          */
 77         if (!flags)
 78                 return 0;
 79 
 80         /*
 81          * Drop the negative dentry, in order to make sure to use the
 82          * case sensitive name which is specified by user if this is
 83          * for creation.
 84          */
 85         if (flags & (LOOKUP_CREATE | LOOKUP_RENAME_TARGET))
 86                 return 0;
 87 
 88         return vfat_revalidate_shortname(dentry);
 89 }
 90 
 91 /* returns the length of a struct qstr, ignoring trailing dots */
 92 static unsigned int __vfat_striptail_len(unsigned int len, const char *name)
 93 {
 94         while (len && name[len - 1] == '.')
 95                 len--;
 96         return len;
 97 }
 98 
 99 static unsigned int vfat_striptail_len(const struct qstr *qstr)
100 {
101         return __vfat_striptail_len(qstr->len, qstr->name);
102 }
103 
104 /*
105  * Compute the hash for the vfat name corresponding to the dentry.
106  * Note: if the name is invalid, we leave the hash code unchanged so
107  * that the existing dentry can be used. The vfat fs routines will
108  * return ENOENT or EINVAL as appropriate.
109  */
110 static int vfat_hash(const struct dentry *dentry, const struct inode *inode,
111                 struct qstr *qstr)
112 {
113         qstr->hash = full_name_hash(qstr->name, vfat_striptail_len(qstr));
114         return 0;
115 }
116 
117 /*
118  * Compute the hash for the vfat name corresponding to the dentry.
119  * Note: if the name is invalid, we leave the hash code unchanged so
120  * that the existing dentry can be used. The vfat fs routines will
121  * return ENOENT or EINVAL as appropriate.
122  */
123 static int vfat_hashi(const struct dentry *dentry, const struct inode *inode,
124                 struct qstr *qstr)
125 {
126         struct nls_table *t = MSDOS_SB(dentry->d_sb)->nls_io;
127         const unsigned char *name;
128         unsigned int len;
129         unsigned long hash;
130 
131         name = qstr->name;
132         len = vfat_striptail_len(qstr);
133 
134         hash = init_name_hash();
135         while (len--)
136                 hash = partial_name_hash(nls_tolower(t, *name++), hash);
137         qstr->hash = end_name_hash(hash);
138 
139         return 0;
140 }
141 
142 /*
143  * Case insensitive compare of two vfat names.
144  */
145 static int vfat_cmpi(const struct dentry *parent, const struct inode *pinode,
146                 const struct dentry *dentry, const struct inode *inode,
147                 unsigned int len, const char *str, const struct qstr *name)
148 {
149         struct nls_table *t = MSDOS_SB(parent->d_sb)->nls_io;
150         unsigned int alen, blen;
151 
152         /* A filename cannot end in '.' or we treat it like it has none */
153         alen = vfat_striptail_len(name);
154         blen = __vfat_striptail_len(len, str);
155         if (alen == blen) {
156                 if (nls_strnicmp(t, name->name, str, alen) == 0)
157                         return 0;
158         }
159         return 1;
160 }
161 
162 /*
163  * Case sensitive compare of two vfat names.
164  */
165 static int vfat_cmp(const struct dentry *parent, const struct inode *pinode,
166                 const struct dentry *dentry, const struct inode *inode,
167                 unsigned int len, const char *str, const struct qstr *name)
168 {
169         unsigned int alen, blen;
170 
171         /* A filename cannot end in '.' or we treat it like it has none */
172         alen = vfat_striptail_len(name);
173         blen = __vfat_striptail_len(len, str);
174         if (alen == blen) {
175                 if (strncmp(name->name, str, alen) == 0)
176                         return 0;
177         }
178         return 1;
179 }
180 
181 static const struct dentry_operations vfat_ci_dentry_ops = {
182         .d_revalidate   = vfat_revalidate_ci,
183         .d_hash         = vfat_hashi,
184         .d_compare      = vfat_cmpi,
185 };
186 
187 static const struct dentry_operations vfat_dentry_ops = {
188         .d_revalidate   = vfat_revalidate,
189         .d_hash         = vfat_hash,
190         .d_compare      = vfat_cmp,
191 };
192 
193 /* Characters that are undesirable in an MS-DOS file name */
194 
195 static inline wchar_t vfat_bad_char(wchar_t w)
196 {
197         return (w < 0x0020)
198             || (w == '*') || (w == '?') || (w == '<') || (w == '>')
199             || (w == '|') || (w == '"') || (w == ':') || (w == '/')
200             || (w == '\\');
201 }
202 
203 static inline wchar_t vfat_replace_char(wchar_t w)
204 {
205         return (w == '[') || (w == ']') || (w == ';') || (w == ',')
206             || (w == '+') || (w == '=');
207 }
208 
209 static wchar_t vfat_skip_char(wchar_t w)
210 {
211         return (w == '.') || (w == ' ');
212 }
213 
214 static inline int vfat_is_used_badchars(const wchar_t *s, int len)
215 {
216         int i;
217 
218         for (i = 0; i < len; i++)
219                 if (vfat_bad_char(s[i]))
220                         return -EINVAL;
221 
222         if (s[i - 1] == ' ') /* last character cannot be space */
223                 return -EINVAL;
224 
225         return 0;
226 }
227 
228 static int vfat_find_form(struct inode *dir, unsigned char *name)
229 {
230         struct fat_slot_info sinfo;
231         int err = fat_scan(dir, name, &sinfo);
232         if (err)
233                 return -ENOENT;
234         brelse(sinfo.bh);
235         return 0;
236 }
237 
238 /*
239  * 1) Valid characters for the 8.3 format alias are any combination of
240  * letters, uppercase alphabets, digits, any of the
241  * following special characters:
242  *     $ % ' ` - @ { } ~ ! # ( ) & _ ^
243  * In this case Longfilename is not stored in disk.
244  *
245  * WinNT's Extension:
246  * File name and extension name is contain uppercase/lowercase
247  * only. And it is expressed by CASE_LOWER_BASE and CASE_LOWER_EXT.
248  *
249  * 2) File name is 8.3 format, but it contain the uppercase and
250  * lowercase char, muliti bytes char, etc. In this case numtail is not
251  * added, but Longfilename is stored.
252  *
253  * 3) When the one except for the above, or the following special
254  * character are contained:
255  *        .   [ ] ; , + =
256  * numtail is added, and Longfilename must be stored in disk .
257  */
258 struct shortname_info {
259         unsigned char lower:1,
260                       upper:1,
261                       valid:1;
262 };
263 #define INIT_SHORTNAME_INFO(x)  do {            \
264         (x)->lower = 1;                         \
265         (x)->upper = 1;                         \
266         (x)->valid = 1;                         \
267 } while (0)
268 
269 static inline int to_shortname_char(struct nls_table *nls,
270                                     unsigned char *buf, int buf_size,
271                                     wchar_t *src, struct shortname_info *info)
272 {
273         int len;
274 
275         if (vfat_skip_char(*src)) {
276                 info->valid = 0;
277                 return 0;
278         }
279         if (vfat_replace_char(*src)) {
280                 info->valid = 0;
281                 buf[0] = '_';
282                 return 1;
283         }
284 
285         len = nls->uni2char(*src, buf, buf_size);
286         if (len <= 0) {
287                 info->valid = 0;
288                 buf[0] = '_';
289                 len = 1;
290         } else if (len == 1) {
291                 unsigned char prev = buf[0];
292 
293                 if (buf[0] >= 0x7F) {
294                         info->lower = 0;
295                         info->upper = 0;
296                 }
297 
298                 buf[0] = nls_toupper(nls, buf[0]);
299                 if (isalpha(buf[0])) {
300                         if (buf[0] == prev)
301                                 info->lower = 0;
302                         else
303                                 info->upper = 0;
304                 }
305         } else {
306                 info->lower = 0;
307                 info->upper = 0;
308         }
309 
310         return len;
311 }
312 
313 /*
314  * Given a valid longname, create a unique shortname.  Make sure the
315  * shortname does not exist
316  * Returns negative number on error, 0 for a normal
317  * return, and 1 for valid shortname
318  */
319 static int vfat_create_shortname(struct inode *dir, struct nls_table *nls,
320                                  wchar_t *uname, int ulen,
321                                  unsigned char *name_res, unsigned char *lcase)
322 {
323         struct fat_mount_options *opts = &MSDOS_SB(dir->i_sb)->options;
324         wchar_t *ip, *ext_start, *end, *name_start;
325         unsigned char base[9], ext[4], buf[5], *p;
326         unsigned char charbuf[NLS_MAX_CHARSET_SIZE];
327         int chl, chi;
328         int sz = 0, extlen, baselen, i, numtail_baselen, numtail2_baselen;
329         int is_shortname;
330         struct shortname_info base_info, ext_info;
331 
332         is_shortname = 1;
333         INIT_SHORTNAME_INFO(&base_info);
334         INIT_SHORTNAME_INFO(&ext_info);
335 
336         /* Now, we need to create a shortname from the long name */
337         ext_start = end = &uname[ulen];
338         while (--ext_start >= uname) {
339                 if (*ext_start == 0x002E) {     /* is `.' */
340                         if (ext_start == end - 1) {
341                                 sz = ulen;
342                                 ext_start = NULL;
343                         }
344                         break;
345                 }
346         }
347 
348         if (ext_start == uname - 1) {
349                 sz = ulen;
350                 ext_start = NULL;
351         } else if (ext_start) {
352                 /*
353                  * Names which start with a dot could be just
354                  * an extension eg. "...test".  In this case Win95
355                  * uses the extension as the name and sets no extension.
356                  */
357                 name_start = &uname[0];
358                 while (name_start < ext_start) {
359                         if (!vfat_skip_char(*name_start))
360                                 break;
361                         name_start++;
362                 }
363                 if (name_start != ext_start) {
364                         sz = ext_start - uname;
365                         ext_start++;
366                 } else {
367                         sz = ulen;
368                         ext_start = NULL;
369                 }
370         }
371 
372         numtail_baselen = 6;
373         numtail2_baselen = 2;
374         for (baselen = i = 0, p = base, ip = uname; i < sz; i++, ip++) {
375                 chl = to_shortname_char(nls, charbuf, sizeof(charbuf),
376                                         ip, &base_info);
377                 if (chl == 0)
378                         continue;
379 
380                 if (baselen < 2 && (baselen + chl) > 2)
381                         numtail2_baselen = baselen;
382                 if (baselen < 6 && (baselen + chl) > 6)
383                         numtail_baselen = baselen;
384                 for (chi = 0; chi < chl; chi++) {
385                         *p++ = charbuf[chi];
386                         baselen++;
387                         if (baselen >= 8)
388                                 break;
389                 }
390                 if (baselen >= 8) {
391                         if ((chi < chl - 1) || (ip + 1) - uname < sz)
392                                 is_shortname = 0;
393                         break;
394                 }
395         }
396         if (baselen == 0) {
397                 return -EINVAL;
398         }
399 
400         extlen = 0;
401         if (ext_start) {
402                 for (p = ext, ip = ext_start; extlen < 3 && ip < end; ip++) {
403                         chl = to_shortname_char(nls, charbuf, sizeof(charbuf),
404                                                 ip, &ext_info);
405                         if (chl == 0)
406                                 continue;
407 
408                         if ((extlen + chl) > 3) {
409                                 is_shortname = 0;
410                                 break;
411                         }
412                         for (chi = 0; chi < chl; chi++) {
413                                 *p++ = charbuf[chi];
414                                 extlen++;
415                         }
416                         if (extlen >= 3) {
417                                 if (ip + 1 != end)
418                                         is_shortname = 0;
419                                 break;
420                         }
421                 }
422         }
423         ext[extlen] = '\0';
424         base[baselen] = '\0';
425 
426         /* Yes, it can happen. ".\xe5" would do it. */
427         if (base[0] == DELETED_FLAG)
428                 base[0] = 0x05;
429 
430         /* OK, at this point we know that base is not longer than 8 symbols,
431          * ext is not longer than 3, base is nonempty, both don't contain
432          * any bad symbols (lowercase transformed to uppercase).
433          */
434 
435         memset(name_res, ' ', MSDOS_NAME);
436         memcpy(name_res, base, baselen);
437         memcpy(name_res + 8, ext, extlen);
438         *lcase = 0;
439         if (is_shortname && base_info.valid && ext_info.valid) {
440                 if (vfat_find_form(dir, name_res) == 0)
441                         return -EEXIST;
442 
443                 if (opts->shortname & VFAT_SFN_CREATE_WIN95) {
444                         return (base_info.upper && ext_info.upper);
445                 } else if (opts->shortname & VFAT_SFN_CREATE_WINNT) {
446                         if ((base_info.upper || base_info.lower) &&
447                             (ext_info.upper || ext_info.lower)) {
448                                 if (!base_info.upper && base_info.lower)
449                                         *lcase |= CASE_LOWER_BASE;
450                                 if (!ext_info.upper && ext_info.lower)
451                                         *lcase |= CASE_LOWER_EXT;
452                                 return 1;
453                         }
454                         return 0;
455                 } else {
456                         BUG();
457                 }
458         }
459 
460         if (opts->numtail == 0)
461                 if (vfat_find_form(dir, name_res) < 0)
462                         return 0;
463 
464         /*
465          * Try to find a unique extension.  This used to
466          * iterate through all possibilities sequentially,
467          * but that gave extremely bad performance.  Windows
468          * only tries a few cases before using random
469          * values for part of the base.
470          */
471 
472         if (baselen > 6) {
473                 baselen = numtail_baselen;
474                 name_res[7] = ' ';
475         }
476         name_res[baselen] = '~';
477         for (i = 1; i < 10; i++) {
478                 name_res[baselen + 1] = i + '';
479                 if (vfat_find_form(dir, name_res) < 0)
480                         return 0;
481         }
482 
483         i = jiffies;
484         sz = (jiffies >> 16) & 0x7;
485         if (baselen > 2) {
486                 baselen = numtail2_baselen;
487                 name_res[7] = ' ';
488         }
489         name_res[baselen + 4] = '~';
490         name_res[baselen + 5] = '1' + sz;
491         while (1) {
492                 snprintf(buf, sizeof(buf), "%04X", i & 0xffff);
493                 memcpy(&name_res[baselen], buf, 4);
494                 if (vfat_find_form(dir, name_res) < 0)
495                         break;
496                 i -= 11;
497         }
498         return 0;
499 }
500 
501 /* Translate a string, including coded sequences into Unicode */
502 static int
503 xlate_to_uni(const unsigned char *name, int len, unsigned char *outname,
504              int *longlen, int *outlen, int escape, int utf8,
505              struct nls_table *nls)
506 {
507         const unsigned char *ip;
508         unsigned char nc;
509         unsigned char *op;
510         unsigned int ec;
511         int i, k, fill;
512         int charlen;
513 
514         if (utf8) {
515                 *outlen = utf8s_to_utf16s(name, len, UTF16_HOST_ENDIAN,
516                                 (wchar_t *) outname, FAT_LFN_LEN + 2);
517                 if (*outlen < 0)
518                         return *outlen;
519                 else if (*outlen > FAT_LFN_LEN)
520                         return -ENAMETOOLONG;
521 
522                 op = &outname[*outlen * sizeof(wchar_t)];
523         } else {
524                 for (i = 0, ip = name, op = outname, *outlen = 0;
525                          i < len && *outlen < FAT_LFN_LEN;
526                          *outlen += 1) {
527                         if (escape && (*ip == ':')) {
528                                 if (i > len - 5)
529                                         return -EINVAL;
530                                 ec = 0;
531                                 for (k = 1; k < 5; k++) {
532                                         nc = ip[k];
533                                         ec <<= 4;
534                                         if (nc >= '' && nc <= '9') {
535                                                 ec |= nc - '';
536                                                 continue;
537                                         }
538                                         if (nc >= 'a' && nc <= 'f') {
539                                                 ec |= nc - ('a' - 10);
540                                                 continue;
541                                         }
542                                         if (nc >= 'A' && nc <= 'F') {
543                                                 ec |= nc - ('A' - 10);
544                                                 continue;
545                                         }
546                                         return -EINVAL;
547                                 }
548                                 *op++ = ec & 0xFF;
549                                 *op++ = ec >> 8;
550                                 ip += 5;
551                                 i += 5;
552                         } else {
553                                 charlen = nls->char2uni(ip, len - i,
554                                                                         (wchar_t *)op);
555                                 if (charlen < 0)
556                                         return -EINVAL;
557                                 ip += charlen;
558                                 i += charlen;
559                                 op += 2;
560                         }
561                 }
562                 if (i < len)
563                         return -ENAMETOOLONG;
564         }
565 
566         *longlen = *outlen;
567         if (*outlen % 13) {
568                 *op++ = 0;
569                 *op++ = 0;
570                 *outlen += 1;
571                 if (*outlen % 13) {
572                         fill = 13 - (*outlen % 13);
573                         for (i = 0; i < fill; i++) {
574                                 *op++ = 0xff;
575                                 *op++ = 0xff;
576                         }
577                         *outlen += fill;
578                 }
579         }
580 
581         return 0;
582 }
583 
584 static int vfat_build_slots(struct inode *dir, const unsigned char *name,
585                             int len, int is_dir, int cluster,
586                             struct timespec *ts,
587                             struct msdos_dir_slot *slots, int *nr_slots)
588 {
589         struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb);
590         struct fat_mount_options *opts = &sbi->options;
591         struct msdos_dir_slot *ps;
592         struct msdos_dir_entry *de;
593         unsigned char cksum, lcase;
594         unsigned char msdos_name[MSDOS_NAME];
595         wchar_t *uname;
596         __le16 time, date;
597         u8 time_cs;
598         int err, ulen, usize, i;
599         loff_t offset;
600 
601         *nr_slots = 0;
602 
603         uname = __getname();
604         if (!uname)
605                 return -ENOMEM;
606 
607         err = xlate_to_uni(name, len, (unsigned char *)uname, &ulen, &usize,
608                            opts->unicode_xlate, opts->utf8, sbi->nls_io);
609         if (err)
610                 goto out_free;
611 
612         err = vfat_is_used_badchars(uname, ulen);
613         if (err)
614                 goto out_free;
615 
616         err = vfat_create_shortname(dir, sbi->nls_disk, uname, ulen,
617                                     msdos_name, &lcase);
618         if (err < 0)
619                 goto out_free;
620         else if (err == 1) {
621                 de = (struct msdos_dir_entry *)slots;
622                 err = 0;
623                 goto shortname;
624         }
625 
626         /* build the entry of long file name */
627         cksum = fat_checksum(msdos_name);
628 
629         *nr_slots = usize / 13;
630         for (ps = slots, i = *nr_slots; i > 0; i--, ps++) {
631                 ps->id = i;
632                 ps->attr = ATTR_EXT;
633                 ps->reserved = 0;
634                 ps->alias_checksum = cksum;
635                 ps->start = 0;
636                 offset = (i - 1) * 13;
637                 fatwchar_to16(ps->name0_4, uname + offset, 5);
638                 fatwchar_to16(ps->name5_10, uname + offset + 5, 6);
639                 fatwchar_to16(ps->name11_12, uname + offset + 11, 2);
640         }
641         slots[0].id |= 0x40;
642         de = (struct msdos_dir_entry *)ps;
643 
644 shortname:
645         /* build the entry of 8.3 alias name */
646         (*nr_slots)++;
647         memcpy(de->name, msdos_name, MSDOS_NAME);
648         de->attr = is_dir ? ATTR_DIR : ATTR_ARCH;
649         de->lcase = lcase;
650         fat_time_unix2fat(sbi, ts, &time, &date, &time_cs);
651         de->time = de->ctime = time;
652         de->date = de->cdate = de->adate = date;
653         de->ctime_cs = time_cs;
654         fat_set_start(de, cluster);
655         de->size = 0;
656 out_free:
657         __putname(uname);
658         return err;
659 }
660 
661 static int vfat_add_entry(struct inode *dir, struct qstr *qname, int is_dir,
662                           int cluster, struct timespec *ts,
663                           struct fat_slot_info *sinfo)
664 {
665         struct msdos_dir_slot *slots;
666         unsigned int len;
667         int err, nr_slots;
668 
669         len = vfat_striptail_len(qname);
670         if (len == 0)
671                 return -ENOENT;
672 
673         slots = kmalloc(sizeof(*slots) * MSDOS_SLOTS, GFP_NOFS);
674         if (slots == NULL)
675                 return -ENOMEM;
676 
677         err = vfat_build_slots(dir, qname->name, len, is_dir, cluster, ts,
678                                slots, &nr_slots);
679         if (err)
680                 goto cleanup;
681 
682         err = fat_add_entries(dir, slots, nr_slots, sinfo);
683         if (err)
684                 goto cleanup;
685 
686         /* update timestamp */
687         dir->i_ctime = dir->i_mtime = dir->i_atime = *ts;
688         if (IS_DIRSYNC(dir))
689                 (void)fat_sync_inode(dir);
690         else
691                 mark_inode_dirty(dir);
692 cleanup:
693         kfree(slots);
694         return err;
695 }
696 
697 static int vfat_find(struct inode *dir, struct qstr *qname,
698                      struct fat_slot_info *sinfo)
699 {
700         unsigned int len = vfat_striptail_len(qname);
701         if (len == 0)
702                 return -ENOENT;
703         return fat_search_long(dir, qname->name, len, sinfo);
704 }
705 
706 /*
707  * (nfsd's) anonymous disconnected dentry?
708  * NOTE: !IS_ROOT() is not anonymous (I.e. d_splice_alias() did the job).
709  */
710 static int vfat_d_anon_disconn(struct dentry *dentry)
711 {
712         return IS_ROOT(dentry) && (dentry->d_flags & DCACHE_DISCONNECTED);
713 }
714 
715 static struct dentry *vfat_lookup(struct inode *dir, struct dentry *dentry,
716                                   unsigned int flags)
717 {
718         struct super_block *sb = dir->i_sb;
719         struct fat_slot_info sinfo;
720         struct inode *inode;
721         struct dentry *alias;
722         int err;
723 
724         mutex_lock(&MSDOS_SB(sb)->s_lock);
725 
726         err = vfat_find(dir, &dentry->d_name, &sinfo);
727         if (err) {
728                 if (err == -ENOENT) {
729                         inode = NULL;
730                         goto out;
731                 }
732                 goto error;
733         }
734 
735         inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
736         brelse(sinfo.bh);
737         if (IS_ERR(inode)) {
738                 err = PTR_ERR(inode);
739                 goto error;
740         }
741 
742         alias = d_find_alias(inode);
743         if (alias && !vfat_d_anon_disconn(alias)) {
744                 /*
745                  * This inode has non anonymous-DCACHE_DISCONNECTED
746                  * dentry. This means, the user did ->lookup() by an
747                  * another name (longname vs 8.3 alias of it) in past.
748                  *
749                  * Switch to new one for reason of locality if possible.
750                  */
751                 BUG_ON(d_unhashed(alias));
752                 if (!S_ISDIR(inode->i_mode))
753                         d_move(alias, dentry);
754                 iput(inode);
755                 mutex_unlock(&MSDOS_SB(sb)->s_lock);
756                 return alias;
757         } else
758                 dput(alias);
759 
760 out:
761         mutex_unlock(&MSDOS_SB(sb)->s_lock);
762         dentry->d_time = dentry->d_parent->d_inode->i_version;
763         dentry = d_splice_alias(inode, dentry);
764         if (dentry)
765                 dentry->d_time = dentry->d_parent->d_inode->i_version;
766         return dentry;
767 
768 error:
769         mutex_unlock(&MSDOS_SB(sb)->s_lock);
770         return ERR_PTR(err);
771 }
772 
773 static int vfat_create(struct inode *dir, struct dentry *dentry, umode_t mode,
774                        bool excl)
775 {
776         struct super_block *sb = dir->i_sb;
777         struct inode *inode;
778         struct fat_slot_info sinfo;
779         struct timespec ts;
780         int err;
781 
782         mutex_lock(&MSDOS_SB(sb)->s_lock);
783 
784         ts = CURRENT_TIME_SEC;
785         err = vfat_add_entry(dir, &dentry->d_name, 0, 0, &ts, &sinfo);
786         if (err)
787                 goto out;
788         dir->i_version++;
789 
790         inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
791         brelse(sinfo.bh);
792         if (IS_ERR(inode)) {
793                 err = PTR_ERR(inode);
794                 goto out;
795         }
796         inode->i_version++;
797         inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
798         /* timestamp is already written, so mark_inode_dirty() is unneeded. */
799 
800         dentry->d_time = dentry->d_parent->d_inode->i_version;
801         d_instantiate(dentry, inode);
802 out:
803         mutex_unlock(&MSDOS_SB(sb)->s_lock);
804         return err;
805 }
806 
807 static int vfat_rmdir(struct inode *dir, struct dentry *dentry)
808 {
809         struct inode *inode = dentry->d_inode;
810         struct super_block *sb = dir->i_sb;
811         struct fat_slot_info sinfo;
812         int err;
813 
814         mutex_lock(&MSDOS_SB(sb)->s_lock);
815 
816         err = fat_dir_empty(inode);
817         if (err)
818                 goto out;
819         err = vfat_find(dir, &dentry->d_name, &sinfo);
820         if (err)
821                 goto out;
822 
823         err = fat_remove_entries(dir, &sinfo);  /* and releases bh */
824         if (err)
825                 goto out;
826         drop_nlink(dir);
827 
828         clear_nlink(inode);
829         inode->i_mtime = inode->i_atime = CURRENT_TIME_SEC;
830         fat_detach(inode);
831 out:
832         mutex_unlock(&MSDOS_SB(sb)->s_lock);
833 
834         return err;
835 }
836 
837 static int vfat_unlink(struct inode *dir, struct dentry *dentry)
838 {
839         struct inode *inode = dentry->d_inode;
840         struct super_block *sb = dir->i_sb;
841         struct fat_slot_info sinfo;
842         int err;
843 
844         mutex_lock(&MSDOS_SB(sb)->s_lock);
845 
846         err = vfat_find(dir, &dentry->d_name, &sinfo);
847         if (err)
848                 goto out;
849 
850         err = fat_remove_entries(dir, &sinfo);  /* and releases bh */
851         if (err)
852                 goto out;
853         clear_nlink(inode);
854         inode->i_mtime = inode->i_atime = CURRENT_TIME_SEC;
855         fat_detach(inode);
856 out:
857         mutex_unlock(&MSDOS_SB(sb)->s_lock);
858 
859         return err;
860 }
861 
862 static int vfat_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
863 {
864         struct super_block *sb = dir->i_sb;
865         struct inode *inode;
866         struct fat_slot_info sinfo;
867         struct timespec ts;
868         int err, cluster;
869 
870         mutex_lock(&MSDOS_SB(sb)->s_lock);
871 
872         ts = CURRENT_TIME_SEC;
873         cluster = fat_alloc_new_dir(dir, &ts);
874         if (cluster < 0) {
875                 err = cluster;
876                 goto out;
877         }
878         err = vfat_add_entry(dir, &dentry->d_name, 1, cluster, &ts, &sinfo);
879         if (err)
880                 goto out_free;
881         dir->i_version++;
882         inc_nlink(dir);
883 
884         inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
885         brelse(sinfo.bh);
886         if (IS_ERR(inode)) {
887                 err = PTR_ERR(inode);
888                 /* the directory was completed, just return a error */
889                 goto out;
890         }
891         inode->i_version++;
892         set_nlink(inode, 2);
893         inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
894         /* timestamp is already written, so mark_inode_dirty() is unneeded. */
895 
896         dentry->d_time = dentry->d_parent->d_inode->i_version;
897         d_instantiate(dentry, inode);
898 
899         mutex_unlock(&MSDOS_SB(sb)->s_lock);
900         return 0;
901 
902 out_free:
903         fat_free_clusters(dir, cluster);
904 out:
905         mutex_unlock(&MSDOS_SB(sb)->s_lock);
906         return err;
907 }
908 
909 static int vfat_rename(struct inode *old_dir, struct dentry *old_dentry,
910                        struct inode *new_dir, struct dentry *new_dentry)
911 {
912         struct buffer_head *dotdot_bh;
913         struct msdos_dir_entry *dotdot_de;
914         struct inode *old_inode, *new_inode;
915         struct fat_slot_info old_sinfo, sinfo;
916         struct timespec ts;
917         loff_t new_i_pos;
918         int err, is_dir, update_dotdot, corrupt = 0;
919         struct super_block *sb = old_dir->i_sb;
920 
921         old_sinfo.bh = sinfo.bh = dotdot_bh = NULL;
922         old_inode = old_dentry->d_inode;
923         new_inode = new_dentry->d_inode;
924         mutex_lock(&MSDOS_SB(sb)->s_lock);
925         err = vfat_find(old_dir, &old_dentry->d_name, &old_sinfo);
926         if (err)
927                 goto out;
928 
929         is_dir = S_ISDIR(old_inode->i_mode);
930         update_dotdot = (is_dir && old_dir != new_dir);
931         if (update_dotdot) {
932                 if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de)) {
933                         err = -EIO;
934                         goto out;
935                 }
936         }
937 
938         ts = CURRENT_TIME_SEC;
939         if (new_inode) {
940                 if (is_dir) {
941                         err = fat_dir_empty(new_inode);
942                         if (err)
943                                 goto out;
944                 }
945                 new_i_pos = MSDOS_I(new_inode)->i_pos;
946                 fat_detach(new_inode);
947         } else {
948                 err = vfat_add_entry(new_dir, &new_dentry->d_name, is_dir, 0,
949                                      &ts, &sinfo);
950                 if (err)
951                         goto out;
952                 new_i_pos = sinfo.i_pos;
953         }
954         new_dir->i_version++;
955 
956         fat_detach(old_inode);
957         fat_attach(old_inode, new_i_pos);
958         if (IS_DIRSYNC(new_dir)) {
959                 err = fat_sync_inode(old_inode);
960                 if (err)
961                         goto error_inode;
962         } else
963                 mark_inode_dirty(old_inode);
964 
965         if (update_dotdot) {
966                 fat_set_start(dotdot_de, MSDOS_I(new_dir)->i_logstart);
967                 mark_buffer_dirty_inode(dotdot_bh, old_inode);
968                 if (IS_DIRSYNC(new_dir)) {
969                         err = sync_dirty_buffer(dotdot_bh);
970                         if (err)
971                                 goto error_dotdot;
972                 }
973                 drop_nlink(old_dir);
974                 if (!new_inode)
975                         inc_nlink(new_dir);
976         }
977 
978         err = fat_remove_entries(old_dir, &old_sinfo);  /* and releases bh */
979         old_sinfo.bh = NULL;
980         if (err)
981                 goto error_dotdot;
982         old_dir->i_version++;
983         old_dir->i_ctime = old_dir->i_mtime = ts;
984         if (IS_DIRSYNC(old_dir))
985                 (void)fat_sync_inode(old_dir);
986         else
987                 mark_inode_dirty(old_dir);
988 
989         if (new_inode) {
990                 drop_nlink(new_inode);
991                 if (is_dir)
992                         drop_nlink(new_inode);
993                 new_inode->i_ctime = ts;
994         }
995 out:
996         brelse(sinfo.bh);
997         brelse(dotdot_bh);
998         brelse(old_sinfo.bh);
999         mutex_unlock(&MSDOS_SB(sb)->s_lock);
1000 
1001         return err;
1002 
1003 error_dotdot:
1004         /* data cluster is shared, serious corruption */
1005         corrupt = 1;
1006 
1007         if (update_dotdot) {
1008                 fat_set_start(dotdot_de, MSDOS_I(old_dir)->i_logstart);
1009                 mark_buffer_dirty_inode(dotdot_bh, old_inode);
1010                 corrupt |= sync_dirty_buffer(dotdot_bh);
1011         }
1012 error_inode:
1013         fat_detach(old_inode);
1014         fat_attach(old_inode, old_sinfo.i_pos);
1015         if (new_inode) {
1016                 fat_attach(new_inode, new_i_pos);
1017                 if (corrupt)
1018                         corrupt |= fat_sync_inode(new_inode);
1019         } else {
1020                 /*
1021                  * If new entry was not sharing the data cluster, it
1022                  * shouldn't be serious corruption.
1023                  */
1024                 int err2 = fat_remove_entries(new_dir, &sinfo);
1025                 if (corrupt)
1026                         corrupt |= err2;
1027                 sinfo.bh = NULL;
1028         }
1029         if (corrupt < 0) {
1030                 fat_fs_error(new_dir->i_sb,
1031                              "%s: Filesystem corrupted (i_pos %lld)",
1032                              __func__, sinfo.i_pos);
1033         }
1034         goto out;
1035 }
1036 
1037 static const struct inode_operations vfat_dir_inode_operations = {
1038         .create         = vfat_create,
1039         .lookup         = vfat_lookup,
1040         .unlink         = vfat_unlink,
1041         .mkdir          = vfat_mkdir,
1042         .rmdir          = vfat_rmdir,
1043         .rename         = vfat_rename,
1044         .setattr        = fat_setattr,
1045         .getattr        = fat_getattr,
1046 };
1047 
1048 static void setup(struct super_block *sb)
1049 {
1050         MSDOS_SB(sb)->dir_ops = &vfat_dir_inode_operations;
1051         if (MSDOS_SB(sb)->options.name_check != 's')
1052                 sb->s_d_op = &vfat_ci_dentry_ops;
1053         else
1054                 sb->s_d_op = &vfat_dentry_ops;
1055 }
1056 
1057 static int vfat_fill_super(struct super_block *sb, void *data, int silent)
1058 {
1059         return fat_fill_super(sb, data, silent, 1, setup);
1060 }
1061 
1062 static struct dentry *vfat_mount(struct file_system_type *fs_type,
1063                        int flags, const char *dev_name,
1064                        void *data)
1065 {
1066         return mount_bdev(fs_type, flags, dev_name, data, vfat_fill_super);
1067 }
1068 
1069 static struct file_system_type vfat_fs_type = {
1070         .owner          = THIS_MODULE,
1071         .name           = "vfat",
1072         .mount          = vfat_mount,
1073         .kill_sb        = kill_block_super,
1074         .fs_flags       = FS_REQUIRES_DEV,
1075 };
1076 MODULE_ALIAS_FS("vfat");
1077 
1078 static int __init init_vfat_fs(void)
1079 {
1080         return register_filesystem(&vfat_fs_type);
1081 }
1082 
1083 static void __exit exit_vfat_fs(void)
1084 {
1085         unregister_filesystem(&vfat_fs_type);
1086 }
1087 
1088 MODULE_LICENSE("GPL");
1089 MODULE_DESCRIPTION("VFAT filesystem support");
1090 MODULE_AUTHOR("Gordon Chaffee");
1091 
1092 module_init(init_vfat_fs)
1093 module_exit(exit_vfat_fs)
1094 

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