fs/fat/namei

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This source file includes following definitions.
vfat_d_version
vfat_d_version_set
vfat_revalidate_shortname
vfat_revalidate
vfat_revalidate_ci
__vfat_striptail_len
vfat_striptail_len
vfat_hash
vfat_hashi
vfat_cmpi
vfat_cmp
vfat_bad_char
vfat_replace_char
vfat_skip_char
vfat_is_used_badchars
vfat_find_form
to_shortname_char
vfat_create_shortname
xlate_to_uni
vfat_build_slots
vfat_add_entry
vfat_find
vfat_lookup
vfat_create
vfat_rmdir
vfat_unlink
vfat_mkdir
vfat_rename
setup
vfat_fill_super
vfat_mount
init_vfat_fs
exit_vfat_fs
   1 // SPDX-License-Identifier: GPL-2.0-only
   2 /*
   3  *  linux/fs/vfat/namei.c
   4  *
   5  *  Written 1992,1993 by Werner Almesberger
   6  *
   7  *  Windows95/Windows NT compatible extended MSDOS filesystem
   8  *    by Gordon Chaffee Copyright (C) 1995.  Send bug reports for the
   9  *    VFAT filesystem to <chaffee@cs.berkeley.edu>.  Specify
  10  *    what file operation caused you trouble and if you can duplicate
  11  *    the problem, send a script that demonstrates it.
  12  *
  13  *  Short name translation 1999, 2001 by Wolfram Pienkoss <wp@bszh.de>
  14  *
  15  *  Support Multibyte characters and cleanup by
  16  *                              OGAWA Hirofumi <hirofumi@mail.parknet.co.jp>
  17  */
  18 
  19 #include <linux/module.h>
  20 #include <linux/ctype.h>
  21 #include <linux/slab.h>
  22 #include <linux/namei.h>
  23 #include <linux/kernel.h>
  24 #include <linux/iversion.h>
  25 #include "fat.h"
  26 
  27 static inline unsigned long vfat_d_version(struct dentry *dentry)
  28 {
  29         return (unsigned long) dentry->d_fsdata;
  30 }
  31 
  32 static inline void vfat_d_version_set(struct dentry *dentry,
  33                                       unsigned long version)
  34 {
  35         dentry->d_fsdata = (void *) version;
  36 }
  37 
  38 /*
  39  * If new entry was created in the parent, it could create the 8.3
  40  * alias (the shortname of logname).  So, the parent may have the
  41  * negative-dentry which matches the created 8.3 alias.
  42  *
  43  * If it happened, the negative dentry isn't actually negative
  44  * anymore.  So, drop it.
  45  */
  46 static int vfat_revalidate_shortname(struct dentry *dentry)
  47 {
  48         int ret = 1;
  49         spin_lock(&dentry->d_lock);
  50         if (!inode_eq_iversion(d_inode(dentry->d_parent), vfat_d_version(dentry)))
  51                 ret = 0;
  52         spin_unlock(&dentry->d_lock);
  53         return ret;
  54 }
  55 
  56 static int vfat_revalidate(struct dentry *dentry, unsigned int flags)
  57 {
  58         if (flags & LOOKUP_RCU)
  59                 return -ECHILD;
  60 
  61         /* This is not negative dentry. Always valid. */
  62         if (d_really_is_positive(dentry))
  63                 return 1;
  64         return vfat_revalidate_shortname(dentry);
  65 }
  66 
  67 static int vfat_revalidate_ci(struct dentry *dentry, unsigned int flags)
  68 {
  69         if (flags & LOOKUP_RCU)
  70                 return -ECHILD;
  71 
  72         /*
  73          * This is not negative dentry. Always valid.
  74          *
  75          * Note, rename() to existing directory entry will have ->d_inode,
  76          * and will use existing name which isn't specified name by user.
  77          *
  78          * We may be able to drop this positive dentry here. But dropping
  79          * positive dentry isn't good idea. So it's unsupported like
  80          * rename("filename", "FILENAME") for now.
  81          */
  82         if (d_really_is_positive(dentry))
  83                 return 1;
  84 
  85         /*
  86          * This may be nfsd (or something), anyway, we can't see the
  87          * intent of this. So, since this can be for creation, drop it.
  88          */
  89         if (!flags)
  90                 return 0;
  91 
  92         /*
  93          * Drop the negative dentry, in order to make sure to use the
  94          * case sensitive name which is specified by user if this is
  95          * for creation.
  96          */
  97         if (flags & (LOOKUP_CREATE | LOOKUP_RENAME_TARGET))
  98                 return 0;
  99 
 100         return vfat_revalidate_shortname(dentry);
 101 }
 102 
 103 /* returns the length of a struct qstr, ignoring trailing dots */
 104 static unsigned int __vfat_striptail_len(unsigned int len, const char *name)
 105 {
 106         while (len && name[len - 1] == '.')
 107                 len--;
 108         return len;
 109 }
 110 
 111 static unsigned int vfat_striptail_len(const struct qstr *qstr)
 112 {
 113         return __vfat_striptail_len(qstr->len, qstr->name);
 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_hash(const struct dentry *dentry, struct qstr *qstr)
 123 {
 124         qstr->hash = full_name_hash(dentry, qstr->name, vfat_striptail_len(qstr));
 125         return 0;
 126 }
 127 
 128 /*
 129  * Compute the hash for the vfat name corresponding to the dentry.
 130  * Note: if the name is invalid, we leave the hash code unchanged so
 131  * that the existing dentry can be used. The vfat fs routines will
 132  * return ENOENT or EINVAL as appropriate.
 133  */
 134 static int vfat_hashi(const struct dentry *dentry, struct qstr *qstr)
 135 {
 136         struct nls_table *t = MSDOS_SB(dentry->d_sb)->nls_io;
 137         const unsigned char *name;
 138         unsigned int len;
 139         unsigned long hash;
 140 
 141         name = qstr->name;
 142         len = vfat_striptail_len(qstr);
 143 
 144         hash = init_name_hash(dentry);
 145         while (len--)
 146                 hash = partial_name_hash(nls_tolower(t, *name++), hash);
 147         qstr->hash = end_name_hash(hash);
 148 
 149         return 0;
 150 }
 151 
 152 /*
 153  * Case insensitive compare of two vfat names.
 154  */
 155 static int vfat_cmpi(const struct dentry *dentry,
 156                 unsigned int len, const char *str, const struct qstr *name)
 157 {
 158         struct nls_table *t = MSDOS_SB(dentry->d_sb)->nls_io;
 159         unsigned int alen, blen;
 160 
 161         /* A filename cannot end in '.' or we treat it like it has none */
 162         alen = vfat_striptail_len(name);
 163         blen = __vfat_striptail_len(len, str);
 164         if (alen == blen) {
 165                 if (nls_strnicmp(t, name->name, str, alen) == 0)
 166                         return 0;
 167         }
 168         return 1;
 169 }
 170 
 171 /*
 172  * Case sensitive compare of two vfat names.
 173  */
 174 static int vfat_cmp(const struct dentry *dentry,
 175                 unsigned int len, const char *str, const struct qstr *name)
 176 {
 177         unsigned int alen, blen;
 178 
 179         /* A filename cannot end in '.' or we treat it like it has none */
 180         alen = vfat_striptail_len(name);
 181         blen = __vfat_striptail_len(len, str);
 182         if (alen == blen) {
 183                 if (strncmp(name->name, str, alen) == 0)
 184                         return 0;
 185         }
 186         return 1;
 187 }
 188 
 189 static const struct dentry_operations vfat_ci_dentry_ops = {
 190         .d_revalidate   = vfat_revalidate_ci,
 191         .d_hash         = vfat_hashi,
 192         .d_compare      = vfat_cmpi,
 193 };
 194 
 195 static const struct dentry_operations vfat_dentry_ops = {
 196         .d_revalidate   = vfat_revalidate,
 197         .d_hash         = vfat_hash,
 198         .d_compare      = vfat_cmp,
 199 };
 200 
 201 /* Characters that are undesirable in an MS-DOS file name */
 202 
 203 static inline wchar_t vfat_bad_char(wchar_t w)
 204 {
 205         return (w < 0x0020)
 206             || (w == '*') || (w == '?') || (w == '<') || (w == '>')
 207             || (w == '|') || (w == '"') || (w == ':') || (w == '/')
 208             || (w == '\\');
 209 }
 210 
 211 static inline wchar_t vfat_replace_char(wchar_t w)
 212 {
 213         return (w == '[') || (w == ']') || (w == ';') || (w == ',')
 214             || (w == '+') || (w == '=');
 215 }
 216 
 217 static wchar_t vfat_skip_char(wchar_t w)
 218 {
 219         return (w == '.') || (w == ' ');
 220 }
 221 
 222 static inline int vfat_is_used_badchars(const wchar_t *s, int len)
 223 {
 224         int i;
 225 
 226         for (i = 0; i < len; i++)
 227                 if (vfat_bad_char(s[i]))
 228                         return -EINVAL;
 229 
 230         if (s[i - 1] == ' ') /* last character cannot be space */
 231                 return -EINVAL;
 232 
 233         return 0;
 234 }
 235 
 236 static int vfat_find_form(struct inode *dir, unsigned char *name)
 237 {
 238         struct fat_slot_info sinfo;
 239         int err = fat_scan(dir, name, &sinfo);
 240         if (err)
 241                 return -ENOENT;
 242         brelse(sinfo.bh);
 243         return 0;
 244 }
 245 
 246 /*
 247  * 1) Valid characters for the 8.3 format alias are any combination of
 248  * letters, uppercase alphabets, digits, any of the
 249  * following special characters:
 250  *     $ % ' ` - @ { } ~ ! # ( ) & _ ^
 251  * In this case Longfilename is not stored in disk.
 252  *
 253  * WinNT's Extension:
 254  * File name and extension name is contain uppercase/lowercase
 255  * only. And it is expressed by CASE_LOWER_BASE and CASE_LOWER_EXT.
 256  *
 257  * 2) File name is 8.3 format, but it contain the uppercase and
 258  * lowercase char, muliti bytes char, etc. In this case numtail is not
 259  * added, but Longfilename is stored.
 260  *
 261  * 3) When the one except for the above, or the following special
 262  * character are contained:
 263  *        .   [ ] ; , + =
 264  * numtail is added, and Longfilename must be stored in disk .
 265  */
 266 struct shortname_info {
 267         unsigned char lower:1,
 268                       upper:1,
 269                       valid:1;
 270 };
 271 #define INIT_SHORTNAME_INFO(x)  do {            \
 272         (x)->lower = 1;                         \
 273         (x)->upper = 1;                         \
 274         (x)->valid = 1;                         \
 275 } while (0)
 276 
 277 static inline int to_shortname_char(struct nls_table *nls,
 278                                     unsigned char *buf, int buf_size,
 279                                     wchar_t *src, struct shortname_info *info)
 280 {
 281         int len;
 282 
 283         if (vfat_skip_char(*src)) {
 284                 info->valid = 0;
 285                 return 0;
 286         }
 287         if (vfat_replace_char(*src)) {
 288                 info->valid = 0;
 289                 buf[0] = '_';
 290                 return 1;
 291         }
 292 
 293         len = nls->uni2char(*src, buf, buf_size);
 294         if (len <= 0) {
 295                 info->valid = 0;
 296                 buf[0] = '_';
 297                 len = 1;
 298         } else if (len == 1) {
 299                 unsigned char prev = buf[0];
 300 
 301                 if (buf[0] >= 0x7F) {
 302                         info->lower = 0;
 303                         info->upper = 0;
 304                 }
 305 
 306                 buf[0] = nls_toupper(nls, buf[0]);
 307                 if (isalpha(buf[0])) {
 308                         if (buf[0] == prev)
 309                                 info->lower = 0;
 310                         else
 311                                 info->upper = 0;
 312                 }
 313         } else {
 314                 info->lower = 0;
 315                 info->upper = 0;
 316         }
 317 
 318         return len;
 319 }
 320 
 321 /*
 322  * Given a valid longname, create a unique shortname.  Make sure the
 323  * shortname does not exist
 324  * Returns negative number on error, 0 for a normal
 325  * return, and 1 for valid shortname
 326  */
 327 static int vfat_create_shortname(struct inode *dir, struct nls_table *nls,
 328                                  wchar_t *uname, int ulen,
 329                                  unsigned char *name_res, unsigned char *lcase)
 330 {
 331         struct fat_mount_options *opts = &MSDOS_SB(dir->i_sb)->options;
 332         wchar_t *ip, *ext_start, *end, *name_start;
 333         unsigned char base[9], ext[4], buf[5], *p;
 334         unsigned char charbuf[NLS_MAX_CHARSET_SIZE];
 335         int chl, chi;
 336         int sz = 0, extlen, baselen, i, numtail_baselen, numtail2_baselen;
 337         int is_shortname;
 338         struct shortname_info base_info, ext_info;
 339 
 340         is_shortname = 1;
 341         INIT_SHORTNAME_INFO(&base_info);
 342         INIT_SHORTNAME_INFO(&ext_info);
 343 
 344         /* Now, we need to create a shortname from the long name */
 345         ext_start = end = &uname[ulen];
 346         while (--ext_start >= uname) {
 347                 if (*ext_start == 0x002E) {     /* is `.' */
 348                         if (ext_start == end - 1) {
 349                                 sz = ulen;
 350                                 ext_start = NULL;
 351                         }
 352                         break;
 353                 }
 354         }
 355 
 356         if (ext_start == uname - 1) {
 357                 sz = ulen;
 358                 ext_start = NULL;
 359         } else if (ext_start) {
 360                 /*
 361                  * Names which start with a dot could be just
 362                  * an extension eg. "...test".  In this case Win95
 363                  * uses the extension as the name and sets no extension.
 364                  */
 365                 name_start = &uname[0];
 366                 while (name_start < ext_start) {
 367                         if (!vfat_skip_char(*name_start))
 368                                 break;
 369                         name_start++;
 370                 }
 371                 if (name_start != ext_start) {
 372                         sz = ext_start - uname;
 373                         ext_start++;
 374                 } else {
 375                         sz = ulen;
 376                         ext_start = NULL;
 377                 }
 378         }
 379 
 380         numtail_baselen = 6;
 381         numtail2_baselen = 2;
 382         for (baselen = i = 0, p = base, ip = uname; i < sz; i++, ip++) {
 383                 chl = to_shortname_char(nls, charbuf, sizeof(charbuf),
 384                                         ip, &base_info);
 385                 if (chl == 0)
 386                         continue;
 387 
 388                 if (baselen < 2 && (baselen + chl) > 2)
 389                         numtail2_baselen = baselen;
 390                 if (baselen < 6 && (baselen + chl) > 6)
 391                         numtail_baselen = baselen;
 392                 for (chi = 0; chi < chl; chi++) {
 393                         *p++ = charbuf[chi];
 394                         baselen++;
 395                         if (baselen >= 8)
 396                                 break;
 397                 }
 398                 if (baselen >= 8) {
 399                         if ((chi < chl - 1) || (ip + 1) - uname < sz)
 400                                 is_shortname = 0;
 401                         break;
 402                 }
 403         }
 404         if (baselen == 0) {
 405                 return -EINVAL;
 406         }
 407 
 408         extlen = 0;
 409         if (ext_start) {
 410                 for (p = ext, ip = ext_start; extlen < 3 && ip < end; ip++) {
 411                         chl = to_shortname_char(nls, charbuf, sizeof(charbuf),
 412                                                 ip, &ext_info);
 413                         if (chl == 0)
 414                                 continue;
 415 
 416                         if ((extlen + chl) > 3) {
 417                                 is_shortname = 0;
 418                                 break;
 419                         }
 420                         for (chi = 0; chi < chl; chi++) {
 421                                 *p++ = charbuf[chi];
 422                                 extlen++;
 423                         }
 424                         if (extlen >= 3) {
 425                                 if (ip + 1 != end)
 426                                         is_shortname = 0;
 427                                 break;
 428                         }
 429                 }
 430         }
 431         ext[extlen] = '\0';
 432         base[baselen] = '\0';
 433 
 434         /* Yes, it can happen. ".\xe5" would do it. */
 435         if (base[0] == DELETED_FLAG)
 436                 base[0] = 0x05;
 437 
 438         /* OK, at this point we know that base is not longer than 8 symbols,
 439          * ext is not longer than 3, base is nonempty, both don't contain
 440          * any bad symbols (lowercase transformed to uppercase).
 441          */
 442 
 443         memset(name_res, ' ', MSDOS_NAME);
 444         memcpy(name_res, base, baselen);
 445         memcpy(name_res + 8, ext, extlen);
 446         *lcase = 0;
 447         if (is_shortname && base_info.valid && ext_info.valid) {
 448                 if (vfat_find_form(dir, name_res) == 0)
 449                         return -EEXIST;
 450 
 451                 if (opts->shortname & VFAT_SFN_CREATE_WIN95) {
 452                         return (base_info.upper && ext_info.upper);
 453                 } else if (opts->shortname & VFAT_SFN_CREATE_WINNT) {
 454                         if ((base_info.upper || base_info.lower) &&
 455                             (ext_info.upper || ext_info.lower)) {
 456                                 if (!base_info.upper && base_info.lower)
 457                                         *lcase |= CASE_LOWER_BASE;
 458                                 if (!ext_info.upper && ext_info.lower)
 459                                         *lcase |= CASE_LOWER_EXT;
 460                                 return 1;
 461                         }
 462                         return 0;
 463                 } else {
 464                         BUG();
 465                 }
 466         }
 467 
 468         if (opts->numtail == 0)
 469                 if (vfat_find_form(dir, name_res) < 0)
 470                         return 0;
 471 
 472         /*
 473          * Try to find a unique extension.  This used to
 474          * iterate through all possibilities sequentially,
 475          * but that gave extremely bad performance.  Windows
 476          * only tries a few cases before using random
 477          * values for part of the base.
 478          */
 479 
 480         if (baselen > 6) {
 481                 baselen = numtail_baselen;
 482                 name_res[7] = ' ';
 483         }
 484         name_res[baselen] = '~';
 485         for (i = 1; i < 10; i++) {
 486                 name_res[baselen + 1] = i + '0';
 487                 if (vfat_find_form(dir, name_res) < 0)
 488                         return 0;
 489         }
 490 
 491         i = jiffies;
 492         sz = (jiffies >> 16) & 0x7;
 493         if (baselen > 2) {
 494                 baselen = numtail2_baselen;
 495                 name_res[7] = ' ';
 496         }
 497         name_res[baselen + 4] = '~';
 498         name_res[baselen + 5] = '1' + sz;
 499         while (1) {
 500                 snprintf(buf, sizeof(buf), "%04X", i & 0xffff);
 501                 memcpy(&name_res[baselen], buf, 4);
 502                 if (vfat_find_form(dir, name_res) < 0)
 503                         break;
 504                 i -= 11;
 505         }
 506         return 0;
 507 }
 508 
 509 /* Translate a string, including coded sequences into Unicode */
 510 static int
 511 xlate_to_uni(const unsigned char *name, int len, unsigned char *outname,
 512              int *longlen, int *outlen, int escape, int utf8,
 513              struct nls_table *nls)
 514 {
 515         const unsigned char *ip;
 516         unsigned char *op;
 517         int i, fill;
 518         int charlen;
 519 
 520         if (utf8) {
 521                 *outlen = utf8s_to_utf16s(name, len, UTF16_HOST_ENDIAN,
 522                                 (wchar_t *) outname, FAT_LFN_LEN + 2);
 523                 if (*outlen < 0)
 524                         return *outlen;
 525                 else if (*outlen > FAT_LFN_LEN)
 526                         return -ENAMETOOLONG;
 527 
 528                 op = &outname[*outlen * sizeof(wchar_t)];
 529         } else {
 530                 for (i = 0, ip = name, op = outname, *outlen = 0;
 531                          i < len && *outlen < FAT_LFN_LEN;
 532                          *outlen += 1) {
 533                         if (escape && (*ip == ':')) {
 534                                 u8 uc[2];
 535 
 536                                 if (i > len - 5)
 537                                         return -EINVAL;
 538 
 539                                 if (hex2bin(uc, ip + 1, 2) < 0)
 540                                         return -EINVAL;
 541 
 542                                 *(wchar_t *)op = uc[0] << 8 | uc[1];
 543 
 544                                 op += 2;
 545                                 ip += 5;
 546                                 i += 5;
 547                         } else {
 548                                 charlen = nls->char2uni(ip, len - i,
 549                                                         (wchar_t *)op);
 550                                 if (charlen < 0)
 551                                         return -EINVAL;
 552                                 ip += charlen;
 553                                 i += charlen;
 554                                 op += 2;
 555                         }
 556                 }
 557                 if (i < len)
 558                         return -ENAMETOOLONG;
 559         }
 560 
 561         *longlen = *outlen;
 562         if (*outlen % 13) {
 563                 *op++ = 0;
 564                 *op++ = 0;
 565                 *outlen += 1;
 566                 if (*outlen % 13) {
 567                         fill = 13 - (*outlen % 13);
 568                         for (i = 0; i < fill; i++) {
 569                                 *op++ = 0xff;
 570                                 *op++ = 0xff;
 571                         }
 572                         *outlen += fill;
 573                 }
 574         }
 575 
 576         return 0;
 577 }
 578 
 579 static int vfat_build_slots(struct inode *dir, const unsigned char *name,
 580                             int len, int is_dir, int cluster,
 581                             struct timespec64 *ts,
 582                             struct msdos_dir_slot *slots, int *nr_slots)
 583 {
 584         struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb);
 585         struct fat_mount_options *opts = &sbi->options;
 586         struct msdos_dir_slot *ps;
 587         struct msdos_dir_entry *de;
 588         unsigned char cksum, lcase;
 589         unsigned char msdos_name[MSDOS_NAME];
 590         wchar_t *uname;
 591         __le16 time, date;
 592         u8 time_cs;
 593         int err, ulen, usize, i;
 594         loff_t offset;
 595 
 596         *nr_slots = 0;
 597 
 598         uname = __getname();
 599         if (!uname)
 600                 return -ENOMEM;
 601 
 602         err = xlate_to_uni(name, len, (unsigned char *)uname, &ulen, &usize,
 603                            opts->unicode_xlate, opts->utf8, sbi->nls_io);
 604         if (err)
 605                 goto out_free;
 606 
 607         err = vfat_is_used_badchars(uname, ulen);
 608         if (err)
 609                 goto out_free;
 610 
 611         err = vfat_create_shortname(dir, sbi->nls_disk, uname, ulen,
 612                                     msdos_name, &lcase);
 613         if (err < 0)
 614                 goto out_free;
 615         else if (err == 1) {
 616                 de = (struct msdos_dir_entry *)slots;
 617                 err = 0;
 618                 goto shortname;
 619         }
 620 
 621         /* build the entry of long file name */
 622         cksum = fat_checksum(msdos_name);
 623 
 624         *nr_slots = usize / 13;
 625         for (ps = slots, i = *nr_slots; i > 0; i--, ps++) {
 626                 ps->id = i;
 627                 ps->attr = ATTR_EXT;
 628                 ps->reserved = 0;
 629                 ps->alias_checksum = cksum;
 630                 ps->start = 0;
 631                 offset = (i - 1) * 13;
 632                 fatwchar_to16(ps->name0_4, uname + offset, 5);
 633                 fatwchar_to16(ps->name5_10, uname + offset + 5, 6);
 634                 fatwchar_to16(ps->name11_12, uname + offset + 11, 2);
 635         }
 636         slots[0].id |= 0x40;
 637         de = (struct msdos_dir_entry *)ps;
 638 
 639 shortname:
 640         /* build the entry of 8.3 alias name */
 641         (*nr_slots)++;
 642         memcpy(de->name, msdos_name, MSDOS_NAME);
 643         de->attr = is_dir ? ATTR_DIR : ATTR_ARCH;
 644         de->lcase = lcase;
 645         fat_time_unix2fat(sbi, ts, &time, &date, &time_cs);
 646         de->time = de->ctime = time;
 647         de->date = de->cdate = de->adate = date;
 648         de->ctime_cs = time_cs;
 649         fat_set_start(de, cluster);
 650         de->size = 0;
 651 out_free:
 652         __putname(uname);
 653         return err;
 654 }
 655 
 656 static int vfat_add_entry(struct inode *dir, const struct qstr *qname,
 657                           int is_dir, int cluster, struct timespec64 *ts,
 658                           struct fat_slot_info *sinfo)
 659 {
 660         struct msdos_dir_slot *slots;
 661         unsigned int len;
 662         int err, nr_slots;
 663 
 664         len = vfat_striptail_len(qname);
 665         if (len == 0)
 666                 return -ENOENT;
 667 
 668         slots = kmalloc_array(MSDOS_SLOTS, sizeof(*slots), GFP_NOFS);
 669         if (slots == NULL)
 670                 return -ENOMEM;
 671 
 672         err = vfat_build_slots(dir, qname->name, len, is_dir, cluster, ts,
 673                                slots, &nr_slots);
 674         if (err)
 675                 goto cleanup;
 676 
 677         err = fat_add_entries(dir, slots, nr_slots, sinfo);
 678         if (err)
 679                 goto cleanup;
 680 
 681         /* update timestamp */
 682         fat_truncate_time(dir, ts, S_CTIME|S_MTIME);
 683         if (IS_DIRSYNC(dir))
 684                 (void)fat_sync_inode(dir);
 685         else
 686                 mark_inode_dirty(dir);
 687 cleanup:
 688         kfree(slots);
 689         return err;
 690 }
 691 
 692 static int vfat_find(struct inode *dir, const struct qstr *qname,
 693                      struct fat_slot_info *sinfo)
 694 {
 695         unsigned int len = vfat_striptail_len(qname);
 696         if (len == 0)
 697                 return -ENOENT;
 698         return fat_search_long(dir, qname->name, len, sinfo);
 699 }
 700 
 701 static struct dentry *vfat_lookup(struct inode *dir, struct dentry *dentry,
 702                                   unsigned int flags)
 703 {
 704         struct super_block *sb = dir->i_sb;
 705         struct fat_slot_info sinfo;
 706         struct inode *inode;
 707         struct dentry *alias;
 708         int err;
 709 
 710         mutex_lock(&MSDOS_SB(sb)->s_lock);
 711 
 712         err = vfat_find(dir, &dentry->d_name, &sinfo);
 713         if (err) {
 714                 if (err == -ENOENT) {
 715                         inode = NULL;
 716                         goto out;
 717                 }
 718                 goto error;
 719         }
 720 
 721         inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
 722         brelse(sinfo.bh);
 723         if (IS_ERR(inode)) {
 724                 err = PTR_ERR(inode);
 725                 goto error;
 726         }
 727 
 728         alias = d_find_alias(inode);
 729         /*
 730          * Checking "alias->d_parent == dentry->d_parent" to make sure
 731          * FS is not corrupted (especially double linked dir).
 732          */
 733         if (alias && alias->d_parent == dentry->d_parent) {
 734                 /*
 735                  * This inode has non anonymous-DCACHE_DISCONNECTED
 736                  * dentry. This means, the user did ->lookup() by an
 737                  * another name (longname vs 8.3 alias of it) in past.
 738                  *
 739                  * Switch to new one for reason of locality if possible.
 740                  */
 741                 if (!S_ISDIR(inode->i_mode))
 742                         d_move(alias, dentry);
 743                 iput(inode);
 744                 mutex_unlock(&MSDOS_SB(sb)->s_lock);
 745                 return alias;
 746         } else
 747                 dput(alias);
 748 
 749 out:
 750         mutex_unlock(&MSDOS_SB(sb)->s_lock);
 751         if (!inode)
 752                 vfat_d_version_set(dentry, inode_query_iversion(dir));
 753         return d_splice_alias(inode, dentry);
 754 error:
 755         mutex_unlock(&MSDOS_SB(sb)->s_lock);
 756         return ERR_PTR(err);
 757 }
 758 
 759 static int vfat_create(struct inode *dir, struct dentry *dentry, umode_t mode,
 760                        bool excl)
 761 {
 762         struct super_block *sb = dir->i_sb;
 763         struct inode *inode;
 764         struct fat_slot_info sinfo;
 765         struct timespec64 ts;
 766         int err;
 767 
 768         mutex_lock(&MSDOS_SB(sb)->s_lock);
 769 
 770         ts = current_time(dir);
 771         err = vfat_add_entry(dir, &dentry->d_name, 0, 0, &ts, &sinfo);
 772         if (err)
 773                 goto out;
 774         inode_inc_iversion(dir);
 775 
 776         inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
 777         brelse(sinfo.bh);
 778         if (IS_ERR(inode)) {
 779                 err = PTR_ERR(inode);
 780                 goto out;
 781         }
 782         inode_inc_iversion(inode);
 783         fat_truncate_time(inode, &ts, S_ATIME|S_CTIME|S_MTIME);
 784         /* timestamp is already written, so mark_inode_dirty() is unneeded. */
 785 
 786         d_instantiate(dentry, inode);
 787 out:
 788         mutex_unlock(&MSDOS_SB(sb)->s_lock);
 789         return err;
 790 }
 791 
 792 static int vfat_rmdir(struct inode *dir, struct dentry *dentry)
 793 {
 794         struct inode *inode = d_inode(dentry);
 795         struct super_block *sb = dir->i_sb;
 796         struct fat_slot_info sinfo;
 797         int err;
 798 
 799         mutex_lock(&MSDOS_SB(sb)->s_lock);
 800 
 801         err = fat_dir_empty(inode);
 802         if (err)
 803                 goto out;
 804         err = vfat_find(dir, &dentry->d_name, &sinfo);
 805         if (err)
 806                 goto out;
 807 
 808         err = fat_remove_entries(dir, &sinfo);  /* and releases bh */
 809         if (err)
 810                 goto out;
 811         drop_nlink(dir);
 812 
 813         clear_nlink(inode);
 814         fat_truncate_time(inode, NULL, S_ATIME|S_MTIME);
 815         fat_detach(inode);
 816         vfat_d_version_set(dentry, inode_query_iversion(dir));
 817 out:
 818         mutex_unlock(&MSDOS_SB(sb)->s_lock);
 819 
 820         return err;
 821 }
 822 
 823 static int vfat_unlink(struct inode *dir, struct dentry *dentry)
 824 {
 825         struct inode *inode = d_inode(dentry);
 826         struct super_block *sb = dir->i_sb;
 827         struct fat_slot_info sinfo;
 828         int err;
 829 
 830         mutex_lock(&MSDOS_SB(sb)->s_lock);
 831 
 832         err = vfat_find(dir, &dentry->d_name, &sinfo);
 833         if (err)
 834                 goto out;
 835 
 836         err = fat_remove_entries(dir, &sinfo);  /* and releases bh */
 837         if (err)
 838                 goto out;
 839         clear_nlink(inode);
 840         fat_truncate_time(inode, NULL, S_ATIME|S_MTIME);
 841         fat_detach(inode);
 842         vfat_d_version_set(dentry, inode_query_iversion(dir));
 843 out:
 844         mutex_unlock(&MSDOS_SB(sb)->s_lock);
 845 
 846         return err;
 847 }
 848 
 849 static int vfat_mkdir(struct inode *dir, struct dentry *dentry, umode_t mode)
 850 {
 851         struct super_block *sb = dir->i_sb;
 852         struct inode *inode;
 853         struct fat_slot_info sinfo;
 854         struct timespec64 ts;
 855         int err, cluster;
 856 
 857         mutex_lock(&MSDOS_SB(sb)->s_lock);
 858 
 859         ts = current_time(dir);
 860         cluster = fat_alloc_new_dir(dir, &ts);
 861         if (cluster < 0) {
 862                 err = cluster;
 863                 goto out;
 864         }
 865         err = vfat_add_entry(dir, &dentry->d_name, 1, cluster, &ts, &sinfo);
 866         if (err)
 867                 goto out_free;
 868         inode_inc_iversion(dir);
 869         inc_nlink(dir);
 870 
 871         inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
 872         brelse(sinfo.bh);
 873         if (IS_ERR(inode)) {
 874                 err = PTR_ERR(inode);
 875                 /* the directory was completed, just return a error */
 876                 goto out;
 877         }
 878         inode_inc_iversion(inode);
 879         set_nlink(inode, 2);
 880         fat_truncate_time(inode, &ts, S_ATIME|S_CTIME|S_MTIME);
 881         /* timestamp is already written, so mark_inode_dirty() is unneeded. */
 882 
 883         d_instantiate(dentry, inode);
 884 
 885         mutex_unlock(&MSDOS_SB(sb)->s_lock);
 886         return 0;
 887 
 888 out_free:
 889         fat_free_clusters(dir, cluster);
 890 out:
 891         mutex_unlock(&MSDOS_SB(sb)->s_lock);
 892         return err;
 893 }
 894 
 895 static int vfat_rename(struct inode *old_dir, struct dentry *old_dentry,
 896                        struct inode *new_dir, struct dentry *new_dentry,
 897                        unsigned int flags)
 898 {
 899         struct buffer_head *dotdot_bh;
 900         struct msdos_dir_entry *dotdot_de;
 901         struct inode *old_inode, *new_inode;
 902         struct fat_slot_info old_sinfo, sinfo;
 903         struct timespec64 ts;
 904         loff_t new_i_pos;
 905         int err, is_dir, update_dotdot, corrupt = 0;
 906         struct super_block *sb = old_dir->i_sb;
 907 
 908         if (flags & ~RENAME_NOREPLACE)
 909                 return -EINVAL;
 910 
 911         old_sinfo.bh = sinfo.bh = dotdot_bh = NULL;
 912         old_inode = d_inode(old_dentry);
 913         new_inode = d_inode(new_dentry);
 914         mutex_lock(&MSDOS_SB(sb)->s_lock);
 915         err = vfat_find(old_dir, &old_dentry->d_name, &old_sinfo);
 916         if (err)
 917                 goto out;
 918 
 919         is_dir = S_ISDIR(old_inode->i_mode);
 920         update_dotdot = (is_dir && old_dir != new_dir);
 921         if (update_dotdot) {
 922                 if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de)) {
 923                         err = -EIO;
 924                         goto out;
 925                 }
 926         }
 927 
 928         ts = current_time(old_dir);
 929         if (new_inode) {
 930                 if (is_dir) {
 931                         err = fat_dir_empty(new_inode);
 932                         if (err)
 933                                 goto out;
 934                 }
 935                 new_i_pos = MSDOS_I(new_inode)->i_pos;
 936                 fat_detach(new_inode);
 937         } else {
 938                 err = vfat_add_entry(new_dir, &new_dentry->d_name, is_dir, 0,
 939                                      &ts, &sinfo);
 940                 if (err)
 941                         goto out;
 942                 new_i_pos = sinfo.i_pos;
 943         }
 944         inode_inc_iversion(new_dir);
 945 
 946         fat_detach(old_inode);
 947         fat_attach(old_inode, new_i_pos);
 948         if (IS_DIRSYNC(new_dir)) {
 949                 err = fat_sync_inode(old_inode);
 950                 if (err)
 951                         goto error_inode;
 952         } else
 953                 mark_inode_dirty(old_inode);
 954 
 955         if (update_dotdot) {
 956                 fat_set_start(dotdot_de, MSDOS_I(new_dir)->i_logstart);
 957                 mark_buffer_dirty_inode(dotdot_bh, old_inode);
 958                 if (IS_DIRSYNC(new_dir)) {
 959                         err = sync_dirty_buffer(dotdot_bh);
 960                         if (err)
 961                                 goto error_dotdot;
 962                 }
 963                 drop_nlink(old_dir);
 964                 if (!new_inode)
 965                         inc_nlink(new_dir);
 966         }
 967 
 968         err = fat_remove_entries(old_dir, &old_sinfo);  /* and releases bh */
 969         old_sinfo.bh = NULL;
 970         if (err)
 971                 goto error_dotdot;
 972         inode_inc_iversion(old_dir);
 973         fat_truncate_time(old_dir, &ts, S_CTIME|S_MTIME);
 974         if (IS_DIRSYNC(old_dir))
 975                 (void)fat_sync_inode(old_dir);
 976         else
 977                 mark_inode_dirty(old_dir);
 978 
 979         if (new_inode) {
 980                 drop_nlink(new_inode);
 981                 if (is_dir)
 982                         drop_nlink(new_inode);
 983                 fat_truncate_time(new_inode, &ts, S_CTIME);
 984         }
 985 out:
 986         brelse(sinfo.bh);
 987         brelse(dotdot_bh);
 988         brelse(old_sinfo.bh);
 989         mutex_unlock(&MSDOS_SB(sb)->s_lock);
 990 
 991         return err;
 992 
 993 error_dotdot:
 994         /* data cluster is shared, serious corruption */
 995         corrupt = 1;
 996 
 997         if (update_dotdot) {
 998                 fat_set_start(dotdot_de, MSDOS_I(old_dir)->i_logstart);
 999                 mark_buffer_dirty_inode(dotdot_bh, old_inode);
1000                 corrupt |= sync_dirty_buffer(dotdot_bh);
1001         }
1002 error_inode:
1003         fat_detach(old_inode);
1004         fat_attach(old_inode, old_sinfo.i_pos);
1005         if (new_inode) {
1006                 fat_attach(new_inode, new_i_pos);
1007                 if (corrupt)
1008                         corrupt |= fat_sync_inode(new_inode);
1009         } else {
1010                 /*
1011                  * If new entry was not sharing the data cluster, it
1012                  * shouldn't be serious corruption.
1013                  */
1014                 int err2 = fat_remove_entries(new_dir, &sinfo);
1015                 if (corrupt)
1016                         corrupt |= err2;
1017                 sinfo.bh = NULL;
1018         }
1019         if (corrupt < 0) {
1020                 fat_fs_error(new_dir->i_sb,
1021                              "%s: Filesystem corrupted (i_pos %lld)",
1022                              __func__, sinfo.i_pos);
1023         }
1024         goto out;
1025 }
1026 
1027 static const struct inode_operations vfat_dir_inode_operations = {
1028         .create         = vfat_create,
1029         .lookup         = vfat_lookup,
1030         .unlink         = vfat_unlink,
1031         .mkdir          = vfat_mkdir,
1032         .rmdir          = vfat_rmdir,
1033         .rename         = vfat_rename,
1034         .setattr        = fat_setattr,
1035         .getattr        = fat_getattr,
1036         .update_time    = fat_update_time,
1037 };
1038 
1039 static void setup(struct super_block *sb)
1040 {
1041         MSDOS_SB(sb)->dir_ops = &vfat_dir_inode_operations;
1042         if (MSDOS_SB(sb)->options.name_check != 's')
1043                 sb->s_d_op = &vfat_ci_dentry_ops;
1044         else
1045                 sb->s_d_op = &vfat_dentry_ops;
1046 }
1047 
1048 static int vfat_fill_super(struct super_block *sb, void *data, int silent)
1049 {
1050         return fat_fill_super(sb, data, silent, 1, setup);
1051 }
1052 
1053 static struct dentry *vfat_mount(struct file_system_type *fs_type,
1054                        int flags, const char *dev_name,
1055                        void *data)
1056 {
1057         return mount_bdev(fs_type, flags, dev_name, data, vfat_fill_super);
1058 }
1059 
1060 static struct file_system_type vfat_fs_type = {
1061         .owner          = THIS_MODULE,
1062         .name           = "vfat",
1063         .mount          = vfat_mount,
1064         .kill_sb        = kill_block_super,
1065         .fs_flags       = FS_REQUIRES_DEV,
1066 };
1067 MODULE_ALIAS_FS("vfat");
1068 
1069 static int __init init_vfat_fs(void)
1070 {
1071         return register_filesystem(&vfat_fs_type);
1072 }
1073 
1074 static void __exit exit_vfat_fs(void)
1075 {
1076         unregister_filesystem(&vfat_fs_type);
1077 }
1078 
1079 MODULE_LICENSE("GPL");
1080 MODULE_DESCRIPTION("VFAT filesystem support");
1081 MODULE_AUTHOR("Gordon Chaffee");
1082 
1083 module_init(init_vfat_fs)
1084 module_exit(exit_vfat_fs)
/* [<][>][^][v][top][bottom][index][help] */
root/fs/fat/namei_vfat.c

DEFINITIONS
