Version:  2.0.40 2.2.26 2.4.37 2.6.39 3.0 3.1 3.2 3.3 3.4 3.5 3.6 3.7 3.8 3.9 3.10 3.11 3.12 3.13 3.14 3.15

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/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, struct qstr *qstr)
111 {
112         qstr->hash = full_name_hash(qstr->name, vfat_striptail_len(qstr));
113         return 0;
114 }
115 
116 /*
117  * Compute the hash for the vfat name corresponding to the dentry.
118  * Note: if the name is invalid, we leave the hash code unchanged so
119  * that the existing dentry can be used. The vfat fs routines will
120  * return ENOENT or EINVAL as appropriate.
121  */
122 static int vfat_hashi(const struct dentry *dentry, struct qstr *qstr)
123 {
124         struct nls_table *t = MSDOS_SB(dentry->d_sb)->nls_io;
125         const unsigned char *name;
126         unsigned int len;
127         unsigned long hash;
128 
129         name = qstr->name;
130         len = vfat_striptail_len(qstr);
131 
132         hash = init_name_hash();
133         while (len--)
134                 hash = partial_name_hash(nls_tolower(t, *name++), hash);
135         qstr->hash = end_name_hash(hash);
136 
137         return 0;
138 }
139 
140 /*
141  * Case insensitive compare of two vfat names.
142  */
143 static int vfat_cmpi(const struct dentry *parent, const struct dentry *dentry,
144                 unsigned int len, const char *str, const struct qstr *name)
145 {
146         struct nls_table *t = MSDOS_SB(parent->d_sb)->nls_io;
147         unsigned int alen, blen;
148 
149         /* A filename cannot end in '.' or we treat it like it has none */
150         alen = vfat_striptail_len(name);
151         blen = __vfat_striptail_len(len, str);
152         if (alen == blen) {
153                 if (nls_strnicmp(t, name->name, str, alen) == 0)
154                         return 0;
155         }
156         return 1;
157 }
158 
159 /*
160  * Case sensitive compare of two vfat names.
161  */
162 static int vfat_cmp(const struct dentry *parent, const struct dentry *dentry,
163                 unsigned int len, const char *str, const struct qstr *name)
164 {
165         unsigned int alen, blen;
166 
167         /* A filename cannot end in '.' or we treat it like it has none */
168         alen = vfat_striptail_len(name);
169         blen = __vfat_striptail_len(len, str);
170         if (alen == blen) {
171                 if (strncmp(name->name, str, alen) == 0)
172                         return 0;
173         }
174         return 1;
175 }
176 
177 static const struct dentry_operations vfat_ci_dentry_ops = {
178         .d_revalidate   = vfat_revalidate_ci,
179         .d_hash         = vfat_hashi,
180         .d_compare      = vfat_cmpi,
181 };
182 
183 static const struct dentry_operations vfat_dentry_ops = {
184         .d_revalidate   = vfat_revalidate,
185         .d_hash         = vfat_hash,
186         .d_compare      = vfat_cmp,
187 };
188 
189 /* Characters that are undesirable in an MS-DOS file name */
190 
191 static inline wchar_t vfat_bad_char(wchar_t w)
192 {
193         return (w < 0x0020)
194             || (w == '*') || (w == '?') || (w == '<') || (w == '>')
195             || (w == '|') || (w == '"') || (w == ':') || (w == '/')
196             || (w == '\\');
197 }
198 
199 static inline wchar_t vfat_replace_char(wchar_t w)
200 {
201         return (w == '[') || (w == ']') || (w == ';') || (w == ',')
202             || (w == '+') || (w == '=');
203 }
204 
205 static wchar_t vfat_skip_char(wchar_t w)
206 {
207         return (w == '.') || (w == ' ');
208 }
209 
210 static inline int vfat_is_used_badchars(const wchar_t *s, int len)
211 {
212         int i;
213 
214         for (i = 0; i < len; i++)
215                 if (vfat_bad_char(s[i]))
216                         return -EINVAL;
217 
218         if (s[i - 1] == ' ') /* last character cannot be space */
219                 return -EINVAL;
220 
221         return 0;
222 }
223 
224 static int vfat_find_form(struct inode *dir, unsigned char *name)
225 {
226         struct fat_slot_info sinfo;
227         int err = fat_scan(dir, name, &sinfo);
228         if (err)
229                 return -ENOENT;
230         brelse(sinfo.bh);
231         return 0;
232 }
233 
234 /*
235  * 1) Valid characters for the 8.3 format alias are any combination of
236  * letters, uppercase alphabets, digits, any of the
237  * following special characters:
238  *     $ % ' ` - @ { } ~ ! # ( ) & _ ^
239  * In this case Longfilename is not stored in disk.
240  *
241  * WinNT's Extension:
242  * File name and extension name is contain uppercase/lowercase
243  * only. And it is expressed by CASE_LOWER_BASE and CASE_LOWER_EXT.
244  *
245  * 2) File name is 8.3 format, but it contain the uppercase and
246  * lowercase char, muliti bytes char, etc. In this case numtail is not
247  * added, but Longfilename is stored.
248  *
249  * 3) When the one except for the above, or the following special
250  * character are contained:
251  *        .   [ ] ; , + =
252  * numtail is added, and Longfilename must be stored in disk .
253  */
254 struct shortname_info {
255         unsigned char lower:1,
256                       upper:1,
257                       valid:1;
258 };
259 #define INIT_SHORTNAME_INFO(x)  do {            \
260         (x)->lower = 1;                         \
261         (x)->upper = 1;                         \
262         (x)->valid = 1;                         \
263 } while (0)
264 
265 static inline int to_shortname_char(struct nls_table *nls,
266                                     unsigned char *buf, int buf_size,
267                                     wchar_t *src, struct shortname_info *info)
268 {
269         int len;
270 
271         if (vfat_skip_char(*src)) {
272                 info->valid = 0;
273                 return 0;
274         }
275         if (vfat_replace_char(*src)) {
276                 info->valid = 0;
277                 buf[0] = '_';
278                 return 1;
279         }
280 
281         len = nls->uni2char(*src, buf, buf_size);
282         if (len <= 0) {
283                 info->valid = 0;
284                 buf[0] = '_';
285                 len = 1;
286         } else if (len == 1) {
287                 unsigned char prev = buf[0];
288 
289                 if (buf[0] >= 0x7F) {
290                         info->lower = 0;
291                         info->upper = 0;
292                 }
293 
294                 buf[0] = nls_toupper(nls, buf[0]);
295                 if (isalpha(buf[0])) {
296                         if (buf[0] == prev)
297                                 info->lower = 0;
298                         else
299                                 info->upper = 0;
300                 }
301         } else {
302                 info->lower = 0;
303                 info->upper = 0;
304         }
305 
306         return len;
307 }
308 
309 /*
310  * Given a valid longname, create a unique shortname.  Make sure the
311  * shortname does not exist
312  * Returns negative number on error, 0 for a normal
313  * return, and 1 for valid shortname
314  */
315 static int vfat_create_shortname(struct inode *dir, struct nls_table *nls,
316                                  wchar_t *uname, int ulen,
317                                  unsigned char *name_res, unsigned char *lcase)
318 {
319         struct fat_mount_options *opts = &MSDOS_SB(dir->i_sb)->options;
320         wchar_t *ip, *ext_start, *end, *name_start;
321         unsigned char base[9], ext[4], buf[5], *p;
322         unsigned char charbuf[NLS_MAX_CHARSET_SIZE];
323         int chl, chi;
324         int sz = 0, extlen, baselen, i, numtail_baselen, numtail2_baselen;
325         int is_shortname;
326         struct shortname_info base_info, ext_info;
327 
328         is_shortname = 1;
329         INIT_SHORTNAME_INFO(&base_info);
330         INIT_SHORTNAME_INFO(&ext_info);
331 
332         /* Now, we need to create a shortname from the long name */
333         ext_start = end = &uname[ulen];
334         while (--ext_start >= uname) {
335                 if (*ext_start == 0x002E) {     /* is `.' */
336                         if (ext_start == end - 1) {
337                                 sz = ulen;
338                                 ext_start = NULL;
339                         }
340                         break;
341                 }
342         }
343 
344         if (ext_start == uname - 1) {
345                 sz = ulen;
346                 ext_start = NULL;
347         } else if (ext_start) {
348                 /*
349                  * Names which start with a dot could be just
350                  * an extension eg. "...test".  In this case Win95
351                  * uses the extension as the name and sets no extension.
352                  */
353                 name_start = &uname[0];
354                 while (name_start < ext_start) {
355                         if (!vfat_skip_char(*name_start))
356                                 break;
357                         name_start++;
358                 }
359                 if (name_start != ext_start) {
360                         sz = ext_start - uname;
361                         ext_start++;
362                 } else {
363                         sz = ulen;
364                         ext_start = NULL;
365                 }
366         }
367 
368         numtail_baselen = 6;
369         numtail2_baselen = 2;
370         for (baselen = i = 0, p = base, ip = uname; i < sz; i++, ip++) {
371                 chl = to_shortname_char(nls, charbuf, sizeof(charbuf),
372                                         ip, &base_info);
373                 if (chl == 0)
374                         continue;
375 
376                 if (baselen < 2 && (baselen + chl) > 2)
377                         numtail2_baselen = baselen;
378                 if (baselen < 6 && (baselen + chl) > 6)
379                         numtail_baselen = baselen;
380                 for (chi = 0; chi < chl; chi++) {
381                         *p++ = charbuf[chi];
382                         baselen++;
383                         if (baselen >= 8)
384                                 break;
385                 }
386                 if (baselen >= 8) {
387                         if ((chi < chl - 1) || (ip + 1) - uname < sz)
388                                 is_shortname = 0;
389                         break;
390                 }
391         }
392         if (baselen == 0) {
393                 return -EINVAL;
394         }
395 
396         extlen = 0;
397         if (ext_start) {
398                 for (p = ext, ip = ext_start; extlen < 3 && ip < end; ip++) {
399                         chl = to_shortname_char(nls, charbuf, sizeof(charbuf),
400                                                 ip, &ext_info);
401                         if (chl == 0)
402                                 continue;
403 
404                         if ((extlen + chl) > 3) {
405                                 is_shortname = 0;
406                                 break;
407                         }
408                         for (chi = 0; chi < chl; chi++) {
409                                 *p++ = charbuf[chi];
410                                 extlen++;
411                         }
412                         if (extlen >= 3) {
413                                 if (ip + 1 != end)
414                                         is_shortname = 0;
415                                 break;
416                         }
417                 }
418         }
419         ext[extlen] = '\0';
420         base[baselen] = '\0';
421 
422         /* Yes, it can happen. ".\xe5" would do it. */
423         if (base[0] == DELETED_FLAG)
424                 base[0] = 0x05;
425 
426         /* OK, at this point we know that base is not longer than 8 symbols,
427          * ext is not longer than 3, base is nonempty, both don't contain
428          * any bad symbols (lowercase transformed to uppercase).
429          */
430 
431         memset(name_res, ' ', MSDOS_NAME);
432         memcpy(name_res, base, baselen);
433         memcpy(name_res + 8, ext, extlen);
434         *lcase = 0;
435         if (is_shortname && base_info.valid && ext_info.valid) {
436                 if (vfat_find_form(dir, name_res) == 0)
437                         return -EEXIST;
438 
439                 if (opts->shortname & VFAT_SFN_CREATE_WIN95) {
440                         return (base_info.upper && ext_info.upper);
441                 } else if (opts->shortname & VFAT_SFN_CREATE_WINNT) {
442                         if ((base_info.upper || base_info.lower) &&
443                             (ext_info.upper || ext_info.lower)) {
444                                 if (!base_info.upper && base_info.lower)
445                                         *lcase |= CASE_LOWER_BASE;
446                                 if (!ext_info.upper && ext_info.lower)
447                                         *lcase |= CASE_LOWER_EXT;
448                                 return 1;
449                         }
450                         return 0;
451                 } else {
452                         BUG();
453                 }
454         }
455 
456         if (opts->numtail == 0)
457                 if (vfat_find_form(dir, name_res) < 0)
458                         return 0;
459 
460         /*
461          * Try to find a unique extension.  This used to
462          * iterate through all possibilities sequentially,
463          * but that gave extremely bad performance.  Windows
464          * only tries a few cases before using random
465          * values for part of the base.
466          */
467 
468         if (baselen > 6) {
469                 baselen = numtail_baselen;
470                 name_res[7] = ' ';
471         }
472         name_res[baselen] = '~';
473         for (i = 1; i < 10; i++) {
474                 name_res[baselen + 1] = i + '';
475                 if (vfat_find_form(dir, name_res) < 0)
476                         return 0;
477         }
478 
479         i = jiffies;
480         sz = (jiffies >> 16) & 0x7;
481         if (baselen > 2) {
482                 baselen = numtail2_baselen;
483                 name_res[7] = ' ';
484         }
485         name_res[baselen + 4] = '~';
486         name_res[baselen + 5] = '1' + sz;
487         while (1) {
488                 snprintf(buf, sizeof(buf), "%04X", i & 0xffff);
489                 memcpy(&name_res[baselen], buf, 4);
490                 if (vfat_find_form(dir, name_res) < 0)
491                         break;
492                 i -= 11;
493         }
494         return 0;
495 }
496 
497 /* Translate a string, including coded sequences into Unicode */
498 static int
499 xlate_to_uni(const unsigned char *name, int len, unsigned char *outname,
500              int *longlen, int *outlen, int escape, int utf8,
501              struct nls_table *nls)
502 {
503         const unsigned char *ip;
504         unsigned char nc;
505         unsigned char *op;
506         unsigned int ec;
507         int i, k, fill;
508         int charlen;
509 
510         if (utf8) {
511                 *outlen = utf8s_to_utf16s(name, len, UTF16_HOST_ENDIAN,
512                                 (wchar_t *) outname, FAT_LFN_LEN + 2);
513                 if (*outlen < 0)
514                         return *outlen;
515                 else if (*outlen > FAT_LFN_LEN)
516                         return -ENAMETOOLONG;
517 
518                 op = &outname[*outlen * sizeof(wchar_t)];
519         } else {
520                 for (i = 0, ip = name, op = outname, *outlen = 0;
521                          i < len && *outlen < FAT_LFN_LEN;
522                          *outlen += 1) {
523                         if (escape && (*ip == ':')) {
524                                 if (i > len - 5)
525                                         return -EINVAL;
526                                 ec = 0;
527                                 for (k = 1; k < 5; k++) {
528                                         nc = ip[k];
529                                         ec <<= 4;
530                                         if (nc >= '' && nc <= '9') {
531                                                 ec |= nc - '';
532                                                 continue;
533                                         }
534                                         if (nc >= 'a' && nc <= 'f') {
535                                                 ec |= nc - ('a' - 10);
536                                                 continue;
537                                         }
538                                         if (nc >= 'A' && nc <= 'F') {
539                                                 ec |= nc - ('A' - 10);
540                                                 continue;
541                                         }
542                                         return -EINVAL;
543                                 }
544                                 *op++ = ec & 0xFF;
545                                 *op++ = ec >> 8;
546                                 ip += 5;
547                                 i += 5;
548                         } else {
549                                 charlen = nls->char2uni(ip, len - i,
550                                                                         (wchar_t *)op);
551                                 if (charlen < 0)
552                                         return -EINVAL;
553                                 ip += charlen;
554                                 i += charlen;
555                                 op += 2;
556                         }
557                 }
558                 if (i < len)
559                         return -ENAMETOOLONG;
560         }
561 
562         *longlen = *outlen;
563         if (*outlen % 13) {
564                 *op++ = 0;
565                 *op++ = 0;
566                 *outlen += 1;
567                 if (*outlen % 13) {
568                         fill = 13 - (*outlen % 13);
569                         for (i = 0; i < fill; i++) {
570                                 *op++ = 0xff;
571                                 *op++ = 0xff;
572                         }
573                         *outlen += fill;
574                 }
575         }
576 
577         return 0;
578 }
579 
580 static int vfat_build_slots(struct inode *dir, const unsigned char *name,
581                             int len, int is_dir, int cluster,
582                             struct timespec *ts,
583                             struct msdos_dir_slot *slots, int *nr_slots)
584 {
585         struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb);
586         struct fat_mount_options *opts = &sbi->options;
587         struct msdos_dir_slot *ps;
588         struct msdos_dir_entry *de;
589         unsigned char cksum, lcase;
590         unsigned char msdos_name[MSDOS_NAME];
591         wchar_t *uname;
592         __le16 time, date;
593         u8 time_cs;
594         int err, ulen, usize, i;
595         loff_t offset;
596 
597         *nr_slots = 0;
598 
599         uname = __getname();
600         if (!uname)
601                 return -ENOMEM;
602 
603         err = xlate_to_uni(name, len, (unsigned char *)uname, &ulen, &usize,
604                            opts->unicode_xlate, opts->utf8, sbi->nls_io);
605         if (err)
606                 goto out_free;
607 
608         err = vfat_is_used_badchars(uname, ulen);
609         if (err)
610                 goto out_free;
611 
612         err = vfat_create_shortname(dir, sbi->nls_disk, uname, ulen,
613                                     msdos_name, &lcase);
614         if (err < 0)
615                 goto out_free;
616         else if (err == 1) {
617                 de = (struct msdos_dir_entry *)slots;
618                 err = 0;
619                 goto shortname;
620         }
621 
622         /* build the entry of long file name */
623         cksum = fat_checksum(msdos_name);
624 
625         *nr_slots = usize / 13;
626         for (ps = slots, i = *nr_slots; i > 0; i--, ps++) {
627                 ps->id = i;
628                 ps->attr = ATTR_EXT;
629                 ps->reserved = 0;
630                 ps->alias_checksum = cksum;
631                 ps->start = 0;
632                 offset = (i - 1) * 13;
633                 fatwchar_to16(ps->name0_4, uname + offset, 5);
634                 fatwchar_to16(ps->name5_10, uname + offset + 5, 6);
635                 fatwchar_to16(ps->name11_12, uname + offset + 11, 2);
636         }
637         slots[0].id |= 0x40;
638         de = (struct msdos_dir_entry *)ps;
639 
640 shortname:
641         /* build the entry of 8.3 alias name */
642         (*nr_slots)++;
643         memcpy(de->name, msdos_name, MSDOS_NAME);
644         de->attr = is_dir ? ATTR_DIR : ATTR_ARCH;
645         de->lcase = lcase;
646         fat_time_unix2fat(sbi, ts, &time, &date, &time_cs);
647         de->time = de->ctime = time;
648         de->date = de->cdate = de->adate = date;
649         de->ctime_cs = time_cs;
650         fat_set_start(de, cluster);
651         de->size = 0;
652 out_free:
653         __putname(uname);
654         return err;
655 }
656 
657 static int vfat_add_entry(struct inode *dir, struct qstr *qname, int is_dir,
658                           int cluster, struct timespec *ts,
659                           struct fat_slot_info *sinfo)
660 {
661         struct msdos_dir_slot *slots;
662         unsigned int len;
663         int err, nr_slots;
664 
665         len = vfat_striptail_len(qname);
666         if (len == 0)
667                 return -ENOENT;
668 
669         slots = kmalloc(sizeof(*slots) * MSDOS_SLOTS, GFP_NOFS);
670         if (slots == NULL)
671                 return -ENOMEM;
672 
673         err = vfat_build_slots(dir, qname->name, len, is_dir, cluster, ts,
674                                slots, &nr_slots);
675         if (err)
676                 goto cleanup;
677 
678         err = fat_add_entries(dir, slots, nr_slots, sinfo);
679         if (err)
680                 goto cleanup;
681 
682         /* update timestamp */
683         dir->i_ctime = dir->i_mtime = dir->i_atime = *ts;
684         if (IS_DIRSYNC(dir))
685                 (void)fat_sync_inode(dir);
686         else
687                 mark_inode_dirty(dir);
688 cleanup:
689         kfree(slots);
690         return err;
691 }
692 
693 static int vfat_find(struct inode *dir, struct qstr *qname,
694                      struct fat_slot_info *sinfo)
695 {
696         unsigned int len = vfat_striptail_len(qname);
697         if (len == 0)
698                 return -ENOENT;
699         return fat_search_long(dir, qname->name, len, sinfo);
700 }
701 
702 /*
703  * (nfsd's) anonymous disconnected dentry?
704  * NOTE: !IS_ROOT() is not anonymous (I.e. d_splice_alias() did the job).
705  */
706 static int vfat_d_anon_disconn(struct dentry *dentry)
707 {
708         return IS_ROOT(dentry) && (dentry->d_flags & DCACHE_DISCONNECTED);
709 }
710 
711 static struct dentry *vfat_lookup(struct inode *dir, struct dentry *dentry,
712                                   unsigned int flags)
713 {
714         struct super_block *sb = dir->i_sb;
715         struct fat_slot_info sinfo;
716         struct inode *inode;
717         struct dentry *alias;
718         int err;
719 
720         mutex_lock(&MSDOS_SB(sb)->s_lock);
721 
722         err = vfat_find(dir, &dentry->d_name, &sinfo);
723         if (err) {
724                 if (err == -ENOENT) {
725                         inode = NULL;
726                         goto out;
727                 }
728                 goto error;
729         }
730 
731         inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
732         brelse(sinfo.bh);
733         if (IS_ERR(inode)) {
734                 err = PTR_ERR(inode);
735                 goto error;
736         }
737 
738         alias = d_find_alias(inode);
739         if (alias && !vfat_d_anon_disconn(alias)) {
740                 /*
741                  * This inode has non anonymous-DCACHE_DISCONNECTED
742                  * dentry. This means, the user did ->lookup() by an
743                  * another name (longname vs 8.3 alias of it) in past.
744                  *
745                  * Switch to new one for reason of locality if possible.
746                  */
747                 BUG_ON(d_unhashed(alias));
748                 if (!S_ISDIR(inode->i_mode))
749                         d_move(alias, dentry);
750                 iput(inode);
751                 mutex_unlock(&MSDOS_SB(sb)->s_lock);
752                 return alias;
753         } else
754                 dput(alias);
755 
756 out:
757         mutex_unlock(&MSDOS_SB(sb)->s_lock);
758         dentry->d_time = dentry->d_parent->d_inode->i_version;
759         dentry = d_splice_alias(inode, dentry);
760         if (dentry)
761                 dentry->d_time = dentry->d_parent->d_inode->i_version;
762         return dentry;
763 
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         dentry->d_time = dentry->d_parent->d_inode->i_version;
797         d_instantiate(dentry, inode);
798 out:
799         mutex_unlock(&MSDOS_SB(sb)->s_lock);
800         return err;
801 }
802 
803 static int vfat_rmdir(struct inode *dir, struct dentry *dentry)
804 {
805         struct inode *inode = dentry->d_inode;
806         struct super_block *sb = dir->i_sb;
807         struct fat_slot_info sinfo;
808         int err;
809 
810         mutex_lock(&MSDOS_SB(sb)->s_lock);
811 
812         err = fat_dir_empty(inode);
813         if (err)
814                 goto out;
815         err = vfat_find(dir, &dentry->d_name, &sinfo);
816         if (err)
817                 goto out;
818 
819         err = fat_remove_entries(dir, &sinfo);  /* and releases bh */
820         if (err)
821                 goto out;
822         drop_nlink(dir);
823 
824         clear_nlink(inode);
825         inode->i_mtime = inode->i_atime = CURRENT_TIME_SEC;
826         fat_detach(inode);
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 = dentry->d_inode;
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 out:
853         mutex_unlock(&MSDOS_SB(sb)->s_lock);
854 
855         return err;
856 }
857 
858 static int vfat_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
859 {
860         struct super_block *sb = dir->i_sb;
861         struct inode *inode;
862         struct fat_slot_info sinfo;
863         struct timespec ts;
864         int err, cluster;
865 
866         mutex_lock(&MSDOS_SB(sb)->s_lock);
867 
868         ts = CURRENT_TIME_SEC;
869         cluster = fat_alloc_new_dir(dir, &ts);
870         if (cluster < 0) {
871                 err = cluster;
872                 goto out;
873         }
874         err = vfat_add_entry(dir, &dentry->d_name, 1, cluster, &ts, &sinfo);
875         if (err)
876                 goto out_free;
877         dir->i_version++;
878         inc_nlink(dir);
879 
880         inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
881         brelse(sinfo.bh);
882         if (IS_ERR(inode)) {
883                 err = PTR_ERR(inode);
884                 /* the directory was completed, just return a error */
885                 goto out;
886         }
887         inode->i_version++;
888         set_nlink(inode, 2);
889         inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
890         /* timestamp is already written, so mark_inode_dirty() is unneeded. */
891 
892         dentry->d_time = dentry->d_parent->d_inode->i_version;
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 = old_dentry->d_inode;
919         new_inode = new_dentry->d_inode;
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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