fs/msdos/namei.c

   1 /*
   2  *  linux/fs/msdos/namei.c
   3  *
   4  *  Written 1992,1993 by Werner Almesberger
   5  *  Hidden files 1995 by Albert Cahalan <albert@ccs.neu.edu> <adc@coe.neu.edu>
   6  *  Rewritten for constant inumbers 1999 by Al Viro
   7  */
   8
   9 #include <linux/module.h>
  10 #include <linux/time.h>
  11 #include <linux/buffer_head.h>
  12 #include <linux/msdos_fs.h>
  13 #include <linux/smp_lock.h>
  14
  15 /* Characters that are undesirable in an MS-DOS file name */
  16 static unsigned char bad_chars[] = "*?<>|\"";
  17 static unsigned char bad_if_strict_pc[] = "+=,; ";
  18 /* GEMDOS is less restrictive */
  19 static unsigned char bad_if_strict_atari[] = " ";
  20
  21 #define bad_if_strict(opts) \
  22         ((opts)->atari ? bad_if_strict_atari : bad_if_strict_pc)
  23
  24 /***** Formats an MS-DOS file name. Rejects invalid names. */
  25 static int msdos_format_name(const unsigned char *name, int len,
  26                              unsigned char *res, struct fat_mount_options *opts)
  27         /*
  28          * name is the proposed name, len is its length, res is
  29          * the resulting name, opts->name_check is either (r)elaxed,
  30          * (n)ormal or (s)trict, opts->dotsOK allows dots at the
  31          * beginning of name (for hidden files)
  32          */
  33 {
  34         unsigned char *walk;
  35         unsigned char c;
  36         int space;
  37
  38         if (name[0] == '.') {   /* dotfile because . and .. already done */
  39                 if (opts->dotsOK) {
  40                         /* Get rid of dot - test for it elsewhere */
  41                         name++;
  42                         len--;
  43                 } else if (!opts->atari)
  44                         return -EINVAL;
  45         }
  46         /*
  47          * disallow names that _really_ start with a dot for MS-DOS,
  48          * GEMDOS does not care
  49          */
  50         space = !opts->atari;
  51         c = 0;
  52         for (walk = res; len && walk - res < 8; walk++) {
  53                 c = *name++;
  54                 len--;
  55                 if (opts->name_check != 'r' && strchr(bad_chars, c))
  56                         return -EINVAL;
  57                 if (opts->name_check == 's' && strchr(bad_if_strict(opts), c))
  58                         return -EINVAL;
  59                 if (c >= 'A' && c <= 'Z' && opts->name_check == 's')
  60                         return -EINVAL;
  61                 if (c < ' ' || c == ':' || c == '\\')
  62                         return -EINVAL;
  63         /*
  64          * 0xE5 is legal as a first character, but we must substitute
  65          * 0x05 because 0xE5 marks deleted files.  Yes, DOS really
  66          * does this.
  67          * It seems that Microsoft hacked DOS to support non-US
  68          * characters after the 0xE5 character was already in use to
  69          * mark deleted files.
  70          */
  71                 if ((res == walk) && (c == 0xE5))
  72                         c = 0x05;
  73                 if (c == '.')
  74                         break;
  75                 space = (c == ' ');
  76                 *walk = (!opts->nocase && c >= 'a' && c <= 'z') ? c - 32 : c;
  77         }
  78         if (space)
  79                 return -EINVAL;
  80         if (opts->name_check == 's' && len && c != '.') {
  81                 c = *name++;
  82                 len--;
  83                 if (c != '.')
  84                         return -EINVAL;
  85         }
  86         while (c != '.' && len--)
  87                 c = *name++;
  88         if (c == '.') {
  89                 while (walk - res < 8)
  90                         *walk++ = ' ';
  91                 while (len > 0 && walk - res < MSDOS_NAME) {
  92                         c = *name++;
  93                         len--;
  94                         if (opts->name_check != 'r' && strchr(bad_chars, c))
  95                                 return -EINVAL;
  96                         if (opts->name_check == 's' &&
  97                             strchr(bad_if_strict(opts), c))
  98                                 return -EINVAL;
  99                         if (c < ' ' || c == ':' || c == '\\')
 100                                 return -EINVAL;
 101                         if (c == '.') {
 102                                 if (opts->name_check == 's')
 103                                         return -EINVAL;
 104                                 break;
 105                         }
 106                         if (c >= 'A' && c <= 'Z' && opts->name_check == 's')
 107                                 return -EINVAL;
 108                         space = c == ' ';
 109                         if (!opts->nocase && c >= 'a' && c <= 'z')
 110                                 *walk++ = c - 32;
 111                         else
 112                                 *walk++ = c;
 113                 }
 114                 if (space)
 115                         return -EINVAL;
 116                 if (opts->name_check == 's' && len)
 117                         return -EINVAL;
 118         }
 119         while (walk - res < MSDOS_NAME)
 120                 *walk++ = ' ';
 121
 122         return 0;
 123 }
 124
 125 /***** Locates a directory entry.  Uses unformatted name. */
 126 static int msdos_find(struct inode *dir, const unsigned char *name, int len,
 127                       struct fat_slot_info *sinfo)
 128 {
 129         struct msdos_sb_info *sbi = MSDOS_SB(dir->i_sb);
 130         unsigned char msdos_name[MSDOS_NAME];
 131         int err;
 132
 133         err = msdos_format_name(name, len, msdos_name, &sbi->options);
 134         if (err)
 135                 return -ENOENT;
 136
 137         err = fat_scan(dir, msdos_name, sinfo);
 138         if (!err && sbi->options.dotsOK) {
 139                 if (name[0] == '.') {
 140                         if (!(sinfo->de->attr & ATTR_HIDDEN))
 141                                 err = -ENOENT;
 142                 } else {
 143                         if (sinfo->de->attr & ATTR_HIDDEN)
 144                                 err = -ENOENT;
 145                 }
 146                 if (err)
 147                         brelse(sinfo->bh);
 148         }
 149         return err;
 150 }
 151
 152 /*
 153  * Compute the hash for the msdos name corresponding to the dentry.
 154  * Note: if the name is invalid, we leave the hash code unchanged so
 155  * that the existing dentry can be used. The msdos fs routines will
 156  * return ENOENT or EINVAL as appropriate.
 157  */
 158 static int msdos_hash(struct dentry *dentry, struct qstr *qstr)
 159 {
 160         struct fat_mount_options *options = &MSDOS_SB(dentry->d_sb)->options;
 161         unsigned char msdos_name[MSDOS_NAME];
 162         int error;
 163
 164         error = msdos_format_name(qstr->name, qstr->len, msdos_name, options);
 165         if (!error)
 166                 qstr->hash = full_name_hash(msdos_name, MSDOS_NAME);
 167         return 0;
 168 }
 169
 170 /*
 171  * Compare two msdos names. If either of the names are invalid,
 172  * we fall back to doing the standard name comparison.
 173  */
 174 static int msdos_cmp(struct dentry *dentry, struct qstr *a, struct qstr *b)
 175 {
 176         struct fat_mount_options *options = &MSDOS_SB(dentry->d_sb)->options;
 177         unsigned char a_msdos_name[MSDOS_NAME], b_msdos_name[MSDOS_NAME];
 178         int error;
 179
 180         error = msdos_format_name(a->name, a->len, a_msdos_name, options);
 181         if (error)
 182                 goto old_compare;
 183         error = msdos_format_name(b->name, b->len, b_msdos_name, options);
 184         if (error)
 185                 goto old_compare;
 186         error = memcmp(a_msdos_name, b_msdos_name, MSDOS_NAME);
 187 out:
 188         return error;
 189
 190 old_compare:
 191         error = 1;
 192         if (a->len == b->len)
 193                 error = memcmp(a->name, b->name, a->len);
 194         goto out;
 195 }
 196
 197 static struct dentry_operations msdos_dentry_operations = {
 198         .d_hash         = msdos_hash,
 199         .d_compare      = msdos_cmp,
 200 };
 201
 202 /*
 203  * AV. Wrappers for FAT sb operations. Is it wise?
 204  */
 205
 206 /***** Get inode using directory and name */
 207 static struct dentry *msdos_lookup(struct inode *dir, struct dentry *dentry,
 208                                    struct nameidata *nd)
 209 {
 210         struct super_block *sb = dir->i_sb;
 211         struct fat_slot_info sinfo;
 212         struct inode *inode = NULL;
 213         int res;
 214
 215         dentry->d_op = &msdos_dentry_operations;
 216
 217         lock_kernel();
 218         res = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo);
 219         if (res == -ENOENT)
 220                 goto add;
 221         if (res < 0)
 222                 goto out;
 223         inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
 224         brelse(sinfo.bh);
 225         if (IS_ERR(inode)) {
 226                 res = PTR_ERR(inode);
 227                 goto out;
 228         }
 229 add:
 230         res = 0;
 231         dentry = d_splice_alias(inode, dentry);
 232         if (dentry)
 233                 dentry->d_op = &msdos_dentry_operations;
 234 out:
 235         unlock_kernel();
 236         if (!res)
 237                 return dentry;
 238         return ERR_PTR(res);
 239 }
 240
 241 /***** Creates a directory entry (name is already formatted). */
 242 static int msdos_add_entry(struct inode *dir, const unsigned char *name,
 243                            int is_dir, int is_hid, int cluster,
 244                            struct timespec *ts, struct fat_slot_info *sinfo)
 245 {
 246         struct msdos_dir_entry de;
 247         __le16 time, date;
 248         int err;
 249
 250         memcpy(de.name, name, MSDOS_NAME);
 251         de.attr = is_dir ? ATTR_DIR : ATTR_ARCH;
 252         if (is_hid)
 253                 de.attr |= ATTR_HIDDEN;
 254         de.lcase = 0;
 255         fat_date_unix2dos(ts->tv_sec, &time, &date);
 256         de.cdate = de.adate = 0;
 257         de.ctime = 0;
 258         de.ctime_cs = 0;
 259         de.time = time;
 260         de.date = date;
 261         de.start = cpu_to_le16(cluster);
 262         de.starthi = cpu_to_le16(cluster >> 16);
 263         de.size = 0;
 264
 265         err = fat_add_entries(dir, &de, 1, sinfo);
 266         if (err)
 267                 return err;
 268
 269         dir->i_ctime = dir->i_mtime = *ts;
 270         if (IS_DIRSYNC(dir))
 271                 (void)fat_sync_inode(dir);
 272         else
 273                 mark_inode_dirty(dir);
 274
 275         return 0;
 276 }
 277
 278 /***** Create a file */
 279 static int msdos_create(struct inode *dir, struct dentry *dentry, int mode,
 280                         struct nameidata *nd)
 281 {
 282         struct super_block *sb = dir->i_sb;
 283         struct inode *inode;
 284         struct fat_slot_info sinfo;
 285         struct timespec ts;
 286         unsigned char msdos_name[MSDOS_NAME];
 287         int err, is_hid;
 288
 289         lock_kernel();
 290
 291         err = msdos_format_name(dentry->d_name.name, dentry->d_name.len,
 292                                 msdos_name, &MSDOS_SB(sb)->options);
 293         if (err)
 294                 goto out;
 295         is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.');
 296         /* Have to do it due to foo vs. .foo conflicts */
 297         if (!fat_scan(dir, msdos_name, &sinfo)) {
 298                 brelse(sinfo.bh);
 299                 err = -EINVAL;
 300                 goto out;
 301         }
 302
 303         ts = CURRENT_TIME_SEC;
 304         err = msdos_add_entry(dir, msdos_name, 0, is_hid, 0, &ts, &sinfo);
 305         if (err)
 306                 goto out;
 307         inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
 308         brelse(sinfo.bh);
 309         if (IS_ERR(inode)) {
 310                 err = PTR_ERR(inode);
 311                 goto out;
 312         }
 313         inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
 314         /* timestamp is already written, so mark_inode_dirty() is unneeded. */
 315
 316         d_instantiate(dentry, inode);
 317 out:
 318         unlock_kernel();
 319         return err;
 320 }
 321
 322 /***** Remove a directory */
 323 static int msdos_rmdir(struct inode *dir, struct dentry *dentry)
 324 {
 325         struct inode *inode = dentry->d_inode;
 326         struct fat_slot_info sinfo;
 327         int err;
 328
 329         lock_kernel();
 330         /*
 331          * Check whether the directory is not in use, then check
 332          * whether it is empty.
 333          */
 334         err = fat_dir_empty(inode);
 335         if (err)
 336                 goto out;
 337         err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo);
 338         if (err)
 339                 goto out;
 340
 341         err = fat_remove_entries(dir, &sinfo);  /* and releases bh */
 342         if (err)
 343                 goto out;
 344         dir->i_nlink--;
 345
 346         inode->i_nlink = 0;
 347         inode->i_ctime = CURRENT_TIME_SEC;
 348         fat_detach(inode);
 349 out:
 350         unlock_kernel();
 351
 352         return err;
 353 }
 354
 355 /***** Make a directory */
 356 static int msdos_mkdir(struct inode *dir, struct dentry *dentry, int mode)
 357 {
 358         struct super_block *sb = dir->i_sb;
 359         struct fat_slot_info sinfo;
 360         struct inode *inode;
 361         unsigned char msdos_name[MSDOS_NAME];
 362         struct timespec ts;
 363         int err, is_hid, cluster;
 364
 365         lock_kernel();
 366
 367         err = msdos_format_name(dentry->d_name.name, dentry->d_name.len,
 368                                 msdos_name, &MSDOS_SB(sb)->options);
 369         if (err)
 370                 goto out;
 371         is_hid = (dentry->d_name.name[0] == '.') && (msdos_name[0] != '.');
 372         /* foo vs .foo situation */
 373         if (!fat_scan(dir, msdos_name, &sinfo)) {
 374                 brelse(sinfo.bh);
 375                 err = -EINVAL;
 376                 goto out;
 377         }
 378
 379         ts = CURRENT_TIME_SEC;
 380         cluster = fat_alloc_new_dir(dir, &ts);
 381         if (cluster < 0) {
 382                 err = cluster;
 383                 goto out;
 384         }
 385         err = msdos_add_entry(dir, msdos_name, 1, is_hid, cluster, &ts, &sinfo);
 386         if (err)
 387                 goto out_free;
 388         dir->i_nlink++;
 389
 390         inode = fat_build_inode(sb, sinfo.de, sinfo.i_pos);
 391         brelse(sinfo.bh);
 392         if (IS_ERR(inode)) {
 393                 err = PTR_ERR(inode);
 394                 /* the directory was completed, just return a error */
 395                 goto out;
 396         }
 397         inode->i_nlink = 2;
 398         inode->i_mtime = inode->i_atime = inode->i_ctime = ts;
 399         /* timestamp is already written, so mark_inode_dirty() is unneeded. */
 400
 401         d_instantiate(dentry, inode);
 402
 403         unlock_kernel();
 404         return 0;
 405
 406 out_free:
 407         fat_free_clusters(dir, cluster);
 408 out:
 409         unlock_kernel();
 410         return err;
 411 }
 412
 413 /***** Unlink a file */
 414 static int msdos_unlink(struct inode *dir, struct dentry *dentry)
 415 {
 416         struct inode *inode = dentry->d_inode;
 417         struct fat_slot_info sinfo;
 418         int err;
 419
 420         lock_kernel();
 421         err = msdos_find(dir, dentry->d_name.name, dentry->d_name.len, &sinfo);
 422         if (err)
 423                 goto out;
 424
 425         err = fat_remove_entries(dir, &sinfo);  /* and releases bh */
 426         if (err)
 427                 goto out;
 428         inode->i_nlink = 0;
 429         inode->i_ctime = CURRENT_TIME_SEC;
 430         fat_detach(inode);
 431 out:
 432         unlock_kernel();
 433
 434         return err;
 435 }
 436
 437 static int do_msdos_rename(struct inode *old_dir, unsigned char *old_name,
 438                            struct dentry *old_dentry,
 439                            struct inode *new_dir, unsigned char *new_name,
 440                            struct dentry *new_dentry, int is_hid)
 441 {
 442         struct buffer_head *dotdot_bh;
 443         struct msdos_dir_entry *dotdot_de;
 444         struct inode *old_inode, *new_inode;
 445         struct fat_slot_info old_sinfo, sinfo;
 446         struct timespec ts;
 447         loff_t dotdot_i_pos, new_i_pos;
 448         int err, old_attrs, is_dir, update_dotdot, corrupt = 0;
 449
 450         old_sinfo.bh = sinfo.bh = dotdot_bh = NULL;
 451         old_inode = old_dentry->d_inode;
 452         new_inode = new_dentry->d_inode;
 453
 454         err = fat_scan(old_dir, old_name, &old_sinfo);
 455         if (err) {
 456                 err = -EIO;
 457                 goto out;
 458         }
 459
 460         is_dir = S_ISDIR(old_inode->i_mode);
 461         update_dotdot = (is_dir && old_dir != new_dir);
 462         if (update_dotdot) {
 463                 if (fat_get_dotdot_entry(old_inode, &dotdot_bh, &dotdot_de,
 464                                          &dotdot_i_pos) < 0) {
 465                         err = -EIO;
 466                         goto out;
 467                 }
 468         }
 469
 470         old_attrs = MSDOS_I(old_inode)->i_attrs;
 471         err = fat_scan(new_dir, new_name, &sinfo);
 472         if (!err) {
 473                 if (!new_inode) {
 474                         /* "foo" -> ".foo" case. just change the ATTR_HIDDEN */
 475                         if (sinfo.de != old_sinfo.de) {
 476                                 err = -EINVAL;
 477                                 goto out;
 478                         }
 479                         if (is_hid)
 480                                 MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN;
 481                         else
 482                                 MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN;
 483                         if (IS_DIRSYNC(old_dir)) {
 484                                 err = fat_sync_inode(old_inode);
 485                                 if (err) {
 486                                         MSDOS_I(old_inode)->i_attrs = old_attrs;
 487                                         goto out;
 488                                 }
 489                         } else
 490                                 mark_inode_dirty(old_inode);
 491
 492                         old_dir->i_version++;
 493                         old_dir->i_ctime = old_dir->i_mtime = CURRENT_TIME_SEC;
 494                         if (IS_DIRSYNC(old_dir))
 495                                 (void)fat_sync_inode(old_dir);
 496                         else
 497                                 mark_inode_dirty(old_dir);
 498                         goto out;
 499                 }
 500         }
 501
 502         ts = CURRENT_TIME_SEC;
 503         if (new_inode) {
 504                 if (err)
 505                         goto out;
 506                 if (is_dir) {
 507                         err = fat_dir_empty(new_inode);
 508                         if (err)
 509                                 goto out;
 510                 }
 511                 new_i_pos = MSDOS_I(new_inode)->i_pos;
 512                 fat_detach(new_inode);
 513         } else {
 514                 err = msdos_add_entry(new_dir, new_name, is_dir, is_hid, 0,
 515                                       &ts, &sinfo);
 516                 if (err)
 517                         goto out;
 518                 new_i_pos = sinfo.i_pos;
 519         }
 520         new_dir->i_version++;
 521
 522         fat_detach(old_inode);
 523         fat_attach(old_inode, new_i_pos);
 524         if (is_hid)
 525                 MSDOS_I(old_inode)->i_attrs |= ATTR_HIDDEN;
 526         else
 527                 MSDOS_I(old_inode)->i_attrs &= ~ATTR_HIDDEN;
 528         if (IS_DIRSYNC(new_dir)) {
 529                 err = fat_sync_inode(old_inode);
 530                 if (err)
 531                         goto error_inode;
 532         } else
 533                 mark_inode_dirty(old_inode);
 534
 535         if (update_dotdot) {
 536                 int start = MSDOS_I(new_dir)->i_logstart;
 537                 dotdot_de->start = cpu_to_le16(start);
 538                 dotdot_de->starthi = cpu_to_le16(start >> 16);
 539                 mark_buffer_dirty(dotdot_bh);
 540                 if (IS_DIRSYNC(new_dir)) {
 541                         err = sync_dirty_buffer(dotdot_bh);
 542                         if (err)
 543                                 goto error_dotdot;
 544                 }
 545                 old_dir->i_nlink--;
 546                 if (!new_inode)
 547                         new_dir->i_nlink++;
 548         }
 549
 550         err = fat_remove_entries(old_dir, &old_sinfo);  /* and releases bh */
 551         old_sinfo.bh = NULL;
 552         if (err)
 553                 goto error_dotdot;
 554         old_dir->i_version++;
 555         old_dir->i_ctime = old_dir->i_mtime = ts;
 556         if (IS_DIRSYNC(old_dir))
 557                 (void)fat_sync_inode(old_dir);
 558         else
 559                 mark_inode_dirty(old_dir);
 560
 561         if (new_inode) {
 562                 if (is_dir)
 563                         new_inode->i_nlink -= 2;
 564                 else
 565                         new_inode->i_nlink--;
 566                 new_inode->i_ctime = ts;
 567         }
 568 out:
 569         brelse(sinfo.bh);
 570         brelse(dotdot_bh);
 571         brelse(old_sinfo.bh);
 572         return err;
 573
 574 error_dotdot:
 575         /* data cluster is shared, serious corruption */
 576         corrupt = 1;
 577
 578         if (update_dotdot) {
 579                 int start = MSDOS_I(old_dir)->i_logstart;
 580                 dotdot_de->start = cpu_to_le16(start);
 581                 dotdot_de->starthi = cpu_to_le16(start >> 16);
 582                 mark_buffer_dirty(dotdot_bh);
 583                 corrupt |= sync_dirty_buffer(dotdot_bh);
 584         }
 585 error_inode:
 586         fat_detach(old_inode);
 587         fat_attach(old_inode, old_sinfo.i_pos);
 588         MSDOS_I(old_inode)->i_attrs = old_attrs;
 589         if (new_inode) {
 590                 fat_attach(new_inode, new_i_pos);
 591                 if (corrupt)
 592                         corrupt |= fat_sync_inode(new_inode);
 593         } else {
 594                 /*
 595                  * If new entry was not sharing the data cluster, it
 596                  * shouldn't be serious corruption.
 597                  */
 598                 int err2 = fat_remove_entries(new_dir, &sinfo);
 599                 if (corrupt)
 600                         corrupt |= err2;
 601                 sinfo.bh = NULL;
 602         }
 603         if (corrupt < 0) {
 604                 fat_fs_panic(new_dir->i_sb,
 605                              "%s: Filesystem corrupted (i_pos %lld)",
 606                              __FUNCTION__, sinfo.i_pos);
 607         }
 608         goto out;
 609 }
 610
 611 /***** Rename, a wrapper for rename_same_dir & rename_diff_dir */
 612 static int msdos_rename(struct inode *old_dir, struct dentry *old_dentry,
 613                         struct inode *new_dir, struct dentry *new_dentry)
 614 {
 615         unsigned char old_msdos_name[MSDOS_NAME], new_msdos_name[MSDOS_NAME];
 616         int err, is_hid;
 617
 618         lock_kernel();
 619
 620         err = msdos_format_name(old_dentry->d_name.name,
 621                                 old_dentry->d_name.len, old_msdos_name,
 622                                 &MSDOS_SB(old_dir->i_sb)->options);
 623         if (err)
 624                 goto out;
 625         err = msdos_format_name(new_dentry->d_name.name,
 626                                 new_dentry->d_name.len, new_msdos_name,
 627                                 &MSDOS_SB(new_dir->i_sb)->options);
 628         if (err)
 629                 goto out;
 630
 631         is_hid =
 632              (new_dentry->d_name.name[0] == '.') && (new_msdos_name[0] != '.');
 633
 634         err = do_msdos_rename(old_dir, old_msdos_name, old_dentry,
 635                               new_dir, new_msdos_name, new_dentry, is_hid);
 636 out:
 637         unlock_kernel();
 638         return err;
 639 }
 640
 641 static struct inode_operations msdos_dir_inode_operations = {
 642         .create         = msdos_create,
 643         .lookup         = msdos_lookup,
 644         .unlink         = msdos_unlink,
 645         .mkdir          = msdos_mkdir,
 646         .rmdir          = msdos_rmdir,
 647         .rename         = msdos_rename,
 648         .setattr        = fat_notify_change,
 649 };
 650
 651 static int msdos_fill_super(struct super_block *sb, void *data, int silent)
 652 {
 653         int res;
 654
 655         res = fat_fill_super(sb, data, silent, &msdos_dir_inode_operations, 0);
 656         if (res)
 657                 return res;
 658
 659         sb->s_flags |= MS_NOATIME;
 660         sb->s_root->d_op = &msdos_dentry_operations;
 661         return 0;
 662 }
 663
 664 static struct super_block *msdos_get_sb(struct file_system_type *fs_type,
 665                                         int flags, const char *dev_name,
 666                                         void *data)
 667 {
 668         return get_sb_bdev(fs_type, flags, dev_name, data, msdos_fill_super);
 669 }
 670
 671 static struct file_system_type msdos_fs_type = {
 672         .owner          = THIS_MODULE,
 673         .name           = "msdos",
 674         .get_sb         = msdos_get_sb,
 675         .kill_sb        = kill_block_super,
 676         .fs_flags       = FS_REQUIRES_DEV,
 677 };
 678
 679 static int __init init_msdos_fs(void)
 680 {
 681         return register_filesystem(&msdos_fs_type);
 682 }
 683
 684 static void __exit exit_msdos_fs(void)
 685 {
 686         unregister_filesystem(&msdos_fs_type);
 687 }
 688
 689 MODULE_LICENSE("GPL");
 690 MODULE_AUTHOR("Werner Almesberger");
 691 MODULE_DESCRIPTION("MS-DOS filesystem support");
 692
 693 module_init(init_msdos_fs)
 694 module_exit(exit_msdos_fs)