Version:  2.0.40 2.2.26 2.4.37 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15 3.16 3.17 3.18 3.19 4.0 4.1

Linux/fs/fat/namei_vfat.c

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

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