fs/fat/inode.c

   1 /*
   2  *  linux/fs/fat/inode.c
   3  *
   4  *  Written 1992,1993 by Werner Almesberger
   5  *  VFAT extensions by Gordon Chaffee, merged with msdos fs by Henrik Storner
   6  *  Rewritten for the constant inumbers support by Al Viro
   7  *
   8  *  Fixes:
   9  *
  10  *      Max Cohan: Fixed invalid FSINFO offset when info_sector is 0
  11  */
  12
  13 #include <linux/module.h>
  14 #include <linux/msdos_fs.h>
  15 #include <linux/nls.h>
  16 #include <linux/kernel.h>
  17 #include <linux/sched.h>
  18 #include <linux/errno.h>
  19 #include <linux/string.h>
  20 #include <linux/bitops.h>
  21 #include <linux/major.h>
  22 #include <linux/blkdev.h>
  23 #include <linux/fs.h>
  24 #include <linux/stat.h>
  25 #include <linux/locks.h>
  26 #include <linux/fat_cvf.h>
  27 #include <linux/slab.h>
  28 #include <linux/smp_lock.h>
  29
  30 #include <asm/uaccess.h>
  31 #include <asm/unaligned.h>
  32
  33 extern struct cvf_format default_cvf;
  34
  35 /* #define FAT_PARANOIA 1 */
  36 #define DEBUG_LEVEL 0
  37 #ifdef FAT_DEBUG
  38 #  define PRINTK(x) printk x
  39 #else
  40 #  define PRINTK(x)
  41 #endif
  42 #if (DEBUG_LEVEL >= 1)
  43 #  define PRINTK1(x) printk x
  44 #else
  45 #  define PRINTK1(x)
  46 #endif
  47
  48 /*
  49  * New FAT inode stuff. We do the following:
  50  *      a) i_ino is constant and has nothing with on-disk location.
  51  *      b) FAT manages its own cache of directory entries.
  52  *      c) *This* cache is indexed by on-disk location.
  53  *      d) inode has an associated directory entry, all right, but
  54  *              it may be unhashed.
  55  *      e) currently entries are stored within struct inode. That should
  56  *              change.
  57  *      f) we deal with races in the following way:
  58  *              1. readdir() and lookup() do FAT-dir-cache lookup.
  59  *              2. rename() unhashes the F-d-c entry and rehashes it in
  60  *                      a new place.
  61  *              3. unlink() and rmdir() unhash F-d-c entry.
  62  *              4. fat_write_inode() checks whether the thing is unhashed.
  63  *                      If it is we silently return. If it isn't we do bread(),
  64  *                      check if the location is still valid and retry if it
  65  *                      isn't. Otherwise we do changes.
  66  *              5. Spinlock is used to protect hash/unhash/location check/lookup
  67  *              6. fat_clear_inode() unhashes the F-d-c entry.
  68  *              7. lookup() and readdir() do igrab() if they find a F-d-c entry
  69  *                      and consider negative result as cache miss.
  70  */
  71
  72 #define FAT_HASH_BITS   8
  73 #define FAT_HASH_SIZE   (1UL << FAT_HASH_BITS)
  74 #define FAT_HASH_MASK   (FAT_HASH_SIZE-1)
  75 static struct list_head fat_inode_hashtable[FAT_HASH_SIZE];
  76 spinlock_t fat_inode_lock = SPIN_LOCK_UNLOCKED;
  77
  78 void fat_hash_init(void)
  79 {
  80         int i;
  81         for(i = 0; i < FAT_HASH_SIZE; i++) {
  82                 INIT_LIST_HEAD(&fat_inode_hashtable[i]);
  83         }
  84 }
  85
  86 static inline unsigned long fat_hash(struct super_block *sb, int i_pos)
  87 {
  88         unsigned long tmp = (unsigned long)i_pos | (unsigned long) sb;
  89         tmp = tmp + (tmp >> FAT_HASH_BITS) + (tmp >> FAT_HASH_BITS * 2);
  90         return tmp & FAT_HASH_MASK;
  91 }
  92
  93 void fat_attach(struct inode *inode, int i_pos)
  94 {
  95         spin_lock(&fat_inode_lock);
  96         MSDOS_I(inode)->i_location = i_pos;
  97         list_add(&MSDOS_I(inode)->i_fat_hash,
  98                 fat_inode_hashtable + fat_hash(inode->i_sb, i_pos));
  99         spin_unlock(&fat_inode_lock);
 100 }
 101
 102 void fat_detach(struct inode *inode)
 103 {
 104         spin_lock(&fat_inode_lock);
 105         MSDOS_I(inode)->i_location = 0;
 106         list_del(&MSDOS_I(inode)->i_fat_hash);
 107         INIT_LIST_HEAD(&MSDOS_I(inode)->i_fat_hash);
 108         spin_unlock(&fat_inode_lock);
 109 }
 110
 111 struct inode *fat_iget(struct super_block *sb, int i_pos)
 112 {
 113         struct list_head *p = fat_inode_hashtable + fat_hash(sb, i_pos);
 114         struct list_head *walk;
 115         struct msdos_inode_info *i;
 116         struct inode *inode = NULL;
 117
 118         spin_lock(&fat_inode_lock);
 119         list_for_each(walk, p) {
 120                 i = list_entry(walk, struct msdos_inode_info, i_fat_hash);
 121                 if (i->i_fat_inode->i_sb != sb)
 122                         continue;
 123                 if (i->i_location != i_pos)
 124                         continue;
 125                 inode = igrab(i->i_fat_inode);
 126                 if (inode)
 127                         break;
 128         }
 129         spin_unlock(&fat_inode_lock);
 130         return inode;
 131 }
 132
 133 static void fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de);
 134
 135 struct inode *fat_build_inode(struct super_block *sb,
 136                                 struct msdos_dir_entry *de, int ino, int *res)
 137 {
 138         struct inode *inode;
 139         *res = 0;
 140         inode = fat_iget(sb, ino);
 141         if (inode)
 142                 goto out;
 143         inode = new_inode(sb);
 144         *res = -ENOMEM;
 145         if (!inode)
 146                 goto out;
 147         *res = 0;
 148         inode->i_ino = iunique(sb, MSDOS_ROOT_INO);
 149         fat_fill_inode(inode, de);
 150         fat_attach(inode, ino);
 151         insert_inode_hash(inode);
 152 out:
 153         return inode;
 154 }
 155
 156 void fat_delete_inode(struct inode *inode)
 157 {
 158         if (!is_bad_inode(inode)) {
 159                 lock_kernel();
 160                 inode->i_size = 0;
 161                 fat_truncate(inode);
 162                 unlock_kernel();
 163         }
 164         clear_inode(inode);
 165 }
 166
 167 void fat_clear_inode(struct inode *inode)
 168 {
 169         if (is_bad_inode(inode))
 170                 return;
 171         lock_kernel();
 172         spin_lock(&fat_inode_lock);
 173         fat_cache_inval_inode(inode);
 174         list_del(&MSDOS_I(inode)->i_fat_hash);
 175         spin_unlock(&fat_inode_lock);
 176         unlock_kernel();
 177 }
 178
 179 void fat_put_super(struct super_block *sb)
 180 {
 181         if (MSDOS_SB(sb)->cvf_format->cvf_version) {
 182                 dec_cvf_format_use_count_by_version(MSDOS_SB(sb)->cvf_format->cvf_version);
 183                 MSDOS_SB(sb)->cvf_format->unmount_cvf(sb);
 184         }
 185         if (MSDOS_SB(sb)->fat_bits == 32) {
 186                 fat_clusters_flush(sb);
 187         }
 188         fat_cache_inval_dev(sb->s_dev);
 189         set_blocksize (sb->s_dev,BLOCK_SIZE);
 190         if (MSDOS_SB(sb)->nls_disk) {
 191                 unload_nls(MSDOS_SB(sb)->nls_disk);
 192                 MSDOS_SB(sb)->nls_disk = NULL;
 193                 MSDOS_SB(sb)->options.codepage = 0;
 194         }
 195         if (MSDOS_SB(sb)->nls_io) {
 196                 unload_nls(MSDOS_SB(sb)->nls_io);
 197                 MSDOS_SB(sb)->nls_io = NULL;
 198         }
 199         /*
 200          * Note: the iocharset option might have been specified
 201          * without enabling nls_io, so check for it here.
 202          */
 203         if (MSDOS_SB(sb)->options.iocharset) {
 204                 kfree(MSDOS_SB(sb)->options.iocharset);
 205                 MSDOS_SB(sb)->options.iocharset = NULL;
 206         }
 207 }
 208
 209
 210 static int parse_options(char *options,int *fat, int *debug,
 211                          struct fat_mount_options *opts,
 212                          char *cvf_format, char *cvf_options)
 213 {
 214         char *this_char,*value,save,*savep;
 215         char *p;
 216         int ret = 1, len;
 217
 218         opts->name_check = 'n';
 219         opts->conversion = 'b';
 220         opts->fs_uid = current->uid;
 221         opts->fs_gid = current->gid;
 222         opts->fs_umask = current->fs->umask;
 223         opts->quiet = opts->sys_immutable = opts->dotsOK = opts->showexec = 0;
 224         opts->codepage = 0;
 225         opts->nocase = 0;
 226         opts->shortname = 0;
 227         opts->utf8 = 0;
 228         opts->iocharset = NULL;
 229         *debug = *fat = 0;
 230
 231         if (!options)
 232                 goto out;
 233         save = 0;
 234         savep = NULL;
 235         for (this_char = strtok(options,","); this_char;
 236              this_char = strtok(NULL,",")) {
 237                 if ((value = strchr(this_char,'=')) != NULL) {
 238                         save = *value;
 239                         savep = value;
 240                         *value++ = 0;
 241                 }
 242                 if (!strcmp(this_char,"check") && value) {
 243                         if (value[0] && !value[1] && strchr("rns",*value))
 244                                 opts->name_check = *value;
 245                         else if (!strcmp(value,"relaxed"))
 246                                 opts->name_check = 'r';
 247                         else if (!strcmp(value,"normal"))
 248                                 opts->name_check = 'n';
 249                         else if (!strcmp(value,"strict"))
 250                                 opts->name_check = 's';
 251                         else ret = 0;
 252                 }
 253                 else if (!strcmp(this_char,"conv") && value) {
 254                         if (value[0] && !value[1] && strchr("bta",*value))
 255                                 opts->conversion = *value;
 256                         else if (!strcmp(value,"binary"))
 257                                 opts->conversion = 'b';
 258                         else if (!strcmp(value,"text"))
 259                                 opts->conversion = 't';
 260                         else if (!strcmp(value,"auto"))
 261                                 opts->conversion = 'a';
 262                         else ret = 0;
 263                 }
 264                 else if (!strcmp(this_char,"dots")) {
 265                         opts->dotsOK = 1;
 266                 }
 267                 else if (!strcmp(this_char,"nocase")) {
 268                         opts->nocase = 1;
 269                 }
 270                 else if (!strcmp(this_char,"nodots")) {
 271                         opts->dotsOK = 0;
 272                 }
 273                 else if (!strcmp(this_char,"showexec")) {
 274                         opts->showexec = 1;
 275                 }
 276                 else if (!strcmp(this_char,"dotsOK") && value) {
 277                         if (!strcmp(value,"yes")) opts->dotsOK = 1;
 278                         else if (!strcmp(value,"no")) opts->dotsOK = 0;
 279                         else ret = 0;
 280                 }
 281                 else if (!strcmp(this_char,"uid")) {
 282                         if (!value || !*value) ret = 0;
 283                         else {
 284                                 opts->fs_uid = simple_strtoul(value,&value,0);
 285                                 if (*value) ret = 0;
 286                         }
 287                 }
 288                 else if (!strcmp(this_char,"gid")) {
 289                         if (!value || !*value) ret= 0;
 290                         else {
 291                                 opts->fs_gid = simple_strtoul(value,&value,0);
 292                                 if (*value) ret = 0;
 293                         }
 294                 }
 295                 else if (!strcmp(this_char,"umask")) {
 296                         if (!value || !*value) ret = 0;
 297                         else {
 298                                 opts->fs_umask = simple_strtoul(value,&value,8);
 299                                 if (*value) ret = 0;
 300                         }
 301                 }
 302                 else if (!strcmp(this_char,"debug")) {
 303                         if (value) ret = 0;
 304                         else *debug = 1;
 305                 }
 306                 else if (!strcmp(this_char,"fat")) {
 307                         if (!value || !*value) ret = 0;
 308                         else {
 309                                 *fat = simple_strtoul(value,&value,0);
 310                                 if (*value || (*fat != 12 && *fat != 16 &&
 311                                                *fat != 32))
 312                                         ret = 0;
 313                         }
 314                 }
 315                 else if (!strcmp(this_char,"quiet")) {
 316                         if (value) ret = 0;
 317                         else opts->quiet = 1;
 318                 }
 319                 else if (!strcmp(this_char,"blocksize")) {
 320                         printk("FAT: blocksize option is obsolete, "
 321                                "not supported now\n");
 322                 }
 323                 else if (!strcmp(this_char,"sys_immutable")) {
 324                         if (value) ret = 0;
 325                         else opts->sys_immutable = 1;
 326                 }
 327                 else if (!strcmp(this_char,"codepage") && value) {
 328                         opts->codepage = simple_strtoul(value,&value,0);
 329                         if (*value) ret = 0;
 330                         else printk ("MSDOS FS: Using codepage %d\n",
 331                                         opts->codepage);
 332                 }
 333                 else if (!strcmp(this_char,"iocharset") && value) {
 334                         p = value;
 335                         while (*value && *value != ',')
 336                                 value++;
 337                         len = value - p;
 338                         if (len) {
 339                                 char *buffer;
 340
 341                                 if (opts->iocharset != NULL) {
 342                                         kfree(opts->iocharset);
 343                                         opts->iocharset = NULL;
 344                                 }
 345                                 buffer = kmalloc(len + 1, GFP_KERNEL);
 346                                 if (buffer != NULL) {
 347                                         opts->iocharset = buffer;
 348                                         memcpy(buffer, p, len);
 349                                         buffer[len] = 0;
 350                                         printk("MSDOS FS: IO charset %s\n", buffer);
 351                                 } else
 352                                         ret = 0;
 353                         }
 354                 }
 355                 else if (!strcmp(this_char,"cvf_format")) {
 356                         if (!value)
 357                                 return 0;
 358                         strncpy(cvf_format,value,20);
 359                 }
 360                 else if (!strcmp(this_char,"cvf_options")) {
 361                         if (!value)
 362                                 return 0;
 363                         strncpy(cvf_options,value,100);
 364                 }
 365
 366                 if (this_char != options) *(this_char-1) = ',';
 367                 if (value) *savep = save;
 368                 if (ret == 0)
 369                         break;
 370         }
 371 out:
 372         return ret;
 373 }
 374
 375 static void fat_read_root(struct inode *inode)
 376 {
 377         struct super_block *sb = inode->i_sb;
 378         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 379         int nr;
 380
 381         INIT_LIST_HEAD(&MSDOS_I(inode)->i_fat_hash);
 382         MSDOS_I(inode)->i_location = 0;
 383         MSDOS_I(inode)->i_fat_inode = inode;
 384         inode->i_uid = sbi->options.fs_uid;
 385         inode->i_gid = sbi->options.fs_gid;
 386         inode->i_version = ++event;
 387         inode->i_generation = 0;
 388         inode->i_mode = (S_IRWXUGO & ~sbi->options.fs_umask) | S_IFDIR;
 389         inode->i_op = sbi->dir_ops;
 390         inode->i_fop = &fat_dir_operations;
 391         if (sbi->fat_bits == 32) {
 392                 MSDOS_I(inode)->i_start = sbi->root_cluster;
 393                 if ((nr = MSDOS_I(inode)->i_start) != 0) {
 394                         while (nr != -1) {
 395                                 inode->i_size += 1 << sbi->cluster_bits;
 396                                 if (!(nr = fat_access(sb, nr, -1))) {
 397                                         printk("Directory %ld: bad FAT\n",
 398                                                inode->i_ino);
 399                                         break;
 400                                 }
 401                         }
 402                 }
 403         } else {
 404                 MSDOS_I(inode)->i_start = 0;
 405                 inode->i_size = sbi->dir_entries * sizeof(struct msdos_dir_entry);
 406         }
 407         inode->i_blksize = 1 << sbi->cluster_bits;
 408         inode->i_blocks = ((inode->i_size + inode->i_blksize - 1)
 409                            & ~(inode->i_blksize - 1)) >> 9;
 410         MSDOS_I(inode)->i_logstart = 0;
 411         MSDOS_I(inode)->mmu_private = inode->i_size;
 412
 413         MSDOS_I(inode)->i_attrs = 0;
 414         inode->i_mtime = inode->i_atime = inode->i_ctime = 0;
 415         MSDOS_I(inode)->i_ctime_ms = 0;
 416         inode->i_nlink = fat_subdirs(inode)+2;
 417 }
 418
 419 /*
 420  * a FAT file handle with fhtype 3 is
 421  *  0/  i_ino - for fast, reliable lookup if still in the cache
 422  *  1/  i_generation - to see if i_ino is still valid
 423  *          bit 0 == 0 iff directory
 424  *  2/  i_location - if ino has changed, but still in cache
 425  *  3/  i_logstart - to semi-verify inode found at i_location
 426  *  4/  parent->i_logstart - maybe used to hunt for the file on disc
 427  *
 428  */
 429 struct dentry *fat_fh_to_dentry(struct super_block *sb, __u32 *fh,
 430                                 int len, int fhtype, int parent)
 431 {
 432         struct inode *inode = NULL;
 433         struct list_head *lp;
 434         struct dentry *result;
 435
 436         if (fhtype != 3)
 437                 return ERR_PTR(-ESTALE);
 438         if (len < 5)
 439                 return ERR_PTR(-ESTALE);
 440         /* We cannot find the parent,
 441            It better just *be* there */
 442         if (parent)
 443                 return ERR_PTR(-ESTALE);
 444
 445         inode = iget(sb, fh[0]);
 446         if (!inode || is_bad_inode(inode) ||
 447             inode->i_generation != fh[1]) {
 448                 if (inode) iput(inode);
 449                 inode = NULL;
 450         }
 451         if (!inode) {
 452                 /* try 2 - see if i_location is in F-d-c
 453                  * require i_logstart to be the same
 454                  * Will fail if you truncate and then re-write
 455                  */
 456
 457                 inode = fat_iget(sb, fh[2]);
 458                 if (inode && MSDOS_I(inode)->i_logstart != fh[3]) {
 459                         iput(inode);
 460                         inode = NULL;
 461                 }
 462         }
 463         if (!inode) {
 464                 /* For now, do nothing
 465                  * What we could do is:
 466                  * follow the file starting at fh[4], and record
 467                  * the ".." entry, and the name of the fh[2] entry.
 468                  * The follow the ".." file finding the next step up.
 469                  * This way we build a path to the root of
 470                  * the tree. If this works, we lookup the path and so
 471                  * get this inode into the cache.
 472                  * Finally try the fat_iget lookup again
 473                  * If that fails, then weare totally out of luck
 474                  * But all that is for another day
 475                  */
 476         }
 477         if (!inode)
 478                 return ERR_PTR(-ESTALE);
 479
 480
 481         /* now to find a dentry.
 482          * If possible, get a well-connected one
 483          *
 484          * Given the way that we found the inode, it *MUST* be
 485          * well-connected, but it is easiest to just copy the
 486          * code.
 487          */
 488         spin_lock(&dcache_lock);
 489         for (lp = inode->i_dentry.next; lp != &inode->i_dentry ; lp=lp->next) {
 490                 result = list_entry(lp,struct dentry, d_alias);
 491                 if (! (result->d_flags & DCACHE_NFSD_DISCONNECTED)) {
 492                         dget_locked(result);
 493                         result->d_vfs_flags |= DCACHE_REFERENCED;
 494                         spin_unlock(&dcache_lock);
 495                         iput(inode);
 496                         return result;
 497                 }
 498         }
 499         spin_unlock(&dcache_lock);
 500         result = d_alloc_root(inode);
 501         if (result == NULL) {
 502                 iput(inode);
 503                 return ERR_PTR(-ENOMEM);
 504         }
 505         result->d_op = sb->s_root->d_op;
 506         result->d_flags |= DCACHE_NFSD_DISCONNECTED;
 507         return result;
 508
 509
 510 }
 511
 512 int fat_dentry_to_fh(struct dentry *de, __u32 *fh, int *lenp, int needparent)
 513 {
 514         int len = *lenp;
 515         struct inode *inode =  de->d_inode;
 516
 517         if (len < 5)
 518                 return 255; /* no room */
 519         *lenp = 5;
 520         fh[0] = inode->i_ino;
 521         fh[1] = inode->i_generation;
 522         fh[2] = MSDOS_I(inode)->i_location;
 523         fh[3] = MSDOS_I(inode)->i_logstart;
 524         fh[4] = MSDOS_I(de->d_parent->d_inode)->i_logstart;
 525         return 3;
 526 }
 527
 528 static struct super_operations fat_sops = {
 529         write_inode:    fat_write_inode,
 530         delete_inode:   fat_delete_inode,
 531         put_super:      fat_put_super,
 532         statfs:         fat_statfs,
 533         clear_inode:    fat_clear_inode,
 534
 535         read_inode:     make_bad_inode,
 536         fh_to_dentry:   fat_fh_to_dentry,
 537         dentry_to_fh:   fat_dentry_to_fh,
 538 };
 539
 540 /*
 541  * Read the super block of an MS-DOS FS.
 542  *
 543  * Note that this may be called from vfat_read_super
 544  * with some fields already initialized.
 545  */
 546 struct super_block *
 547 fat_read_super(struct super_block *sb, void *data, int silent,
 548                 struct inode_operations *fs_dir_inode_ops)
 549 {
 550         struct inode *root_inode;
 551         struct buffer_head *bh;
 552         struct fat_boot_sector *b;
 553         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 554         char *p;
 555         int logical_sector_size, hard_blksize, fat_clusters = 0;
 556         unsigned int total_sectors, rootdir_sectors;
 557         int fat32, debug, error, fat, cp;
 558         struct fat_mount_options opts;
 559         char buf[50];
 560         int i;
 561         char cvf_format[21];
 562         char cvf_options[101];
 563
 564         cvf_format[0] = '\0';
 565         cvf_options[0] = '\0';
 566         sbi->cvf_format = NULL;
 567         sbi->private_data = NULL;
 568
 569         sbi->dir_ops = fs_dir_inode_ops;
 570
 571         sb->s_maxbytes = MAX_NON_LFS;
 572         sb->s_op = &fat_sops;
 573
 574         hard_blksize = get_hardsect_size(sb->s_dev);
 575         if (!hard_blksize)
 576                 hard_blksize = 512;
 577
 578         opts.isvfat = sbi->options.isvfat;
 579         if (!parse_options((char *) data, &fat, &debug, &opts,
 580                            cvf_format, cvf_options))
 581                 goto out_fail;
 582         /* N.B. we should parse directly into the sb structure */
 583         memcpy(&(sbi->options), &opts, sizeof(struct fat_mount_options));
 584
 585         fat_cache_init();
 586
 587         sb->s_blocksize = hard_blksize;
 588         set_blocksize(sb->s_dev, hard_blksize);
 589         bh = sb_bread(sb, 0);
 590         if (bh == NULL) {
 591                 printk("FAT: unable to read boot sector\n");
 592                 goto out_fail;
 593         }
 594
 595 /*
 596  * The DOS3 partition size limit is *not* 32M as many people think.
 597  * Instead, it is 64K sectors (with the usual sector size being
 598  * 512 bytes, leading to a 32M limit).
 599  *
 600  * DOS 3 partition managers got around this problem by faking a
 601  * larger sector size, ie treating multiple physical sectors as
 602  * a single logical sector.
 603  *
 604  * We can accommodate this scheme by adjusting our cluster size,
 605  * fat_start, and data_start by an appropriate value.
 606  *
 607  * (by Drew Eckhardt)
 608  */
 609
 610
 611         b = (struct fat_boot_sector *) bh->b_data;
 612         logical_sector_size =
 613                 CF_LE_W(get_unaligned((unsigned short *) &b->sector_size));
 614         if (!logical_sector_size
 615             || (logical_sector_size & (logical_sector_size - 1))) {
 616                 printk("FAT: bogus logical sector size %d\n",
 617                        logical_sector_size);
 618                 brelse(bh);
 619                 goto out_invalid;
 620         }
 621
 622         sbi->cluster_size = b->cluster_size;
 623         if (!sbi->cluster_size
 624             || (sbi->cluster_size & (sbi->cluster_size - 1))) {
 625                 printk("FAT: bogus cluster size %d\n", sbi->cluster_size);
 626                 brelse(bh);
 627                 goto out_invalid;
 628         }
 629
 630         if (logical_sector_size < hard_blksize) {
 631                 printk("FAT: logical sector size too small for device"
 632                        " (logical sector size = %d)\n", logical_sector_size);
 633                 brelse(bh);
 634                 goto out_invalid;
 635         }
 636
 637         sbi->cluster_bits = ffs(logical_sector_size * sbi->cluster_size) - 1;
 638         sbi->fats = b->fats;
 639         sbi->fat_start = CF_LE_W(b->reserved);
 640         if (!b->fat_length && b->fat32_length) {
 641                 struct fat_boot_fsinfo *fsinfo;
 642                 struct buffer_head *fsinfo_bh;
 643                 int fsinfo_block, fsinfo_offset;
 644
 645                 /* Must be FAT32 */
 646                 fat32 = 1;
 647                 sbi->fat_length = CF_LE_L(b->fat32_length);
 648                 sbi->root_cluster = CF_LE_L(b->root_cluster);
 649
 650                 sbi->fsinfo_sector = CF_LE_W(b->info_sector);
 651                 /* MC - if info_sector is 0, don't multiply by 0 */
 652                 if (sbi->fsinfo_sector == 0)
 653                         sbi->fsinfo_sector = 1;
 654
 655                 fsinfo_block =
 656                         (sbi->fsinfo_sector * logical_sector_size) / hard_blksize;
 657                 fsinfo_offset =
 658                         (sbi->fsinfo_sector * logical_sector_size) % hard_blksize;
 659                 fsinfo_bh = bh;
 660                 if (fsinfo_block != 0) {
 661                         fsinfo_bh = sb_bread(sb, fsinfo_block);
 662                         if (fsinfo_bh == NULL) {
 663                                 printk("FAT: bread failed, FSINFO block"
 664                                        " (blocknr = %d)\n", fsinfo_block);
 665                                 brelse(bh);
 666                                 goto out_invalid;
 667                         }
 668                 }
 669                 fsinfo = (struct fat_boot_fsinfo *)&fsinfo_bh->b_data[fsinfo_offset];
 670                 if (!IS_FSINFO(fsinfo)) {
 671                         printk("FAT: Did not find valid FSINFO signature.\n"
 672                                "Found signature1 0x%x signature2 0x%x sector=%ld.\n",
 673                                CF_LE_L(fsinfo->signature1),
 674                                CF_LE_L(fsinfo->signature2),
 675                                sbi->fsinfo_sector);
 676                 } else {
 677                         sbi->free_clusters = CF_LE_L(fsinfo->free_clusters);
 678                 }
 679
 680                 if (fsinfo_block != 0)
 681                         brelse(fsinfo_bh);
 682         } else {
 683                 fat32 = 0;
 684                 sbi->fat_length = CF_LE_W(b->fat_length);
 685                 sbi->root_cluster = 0;
 686                 sbi->free_clusters = -1; /* Don't know yet */
 687         }
 688
 689         sbi->dir_per_block = logical_sector_size / sizeof(struct msdos_dir_entry);
 690         sbi->dir_per_block_bits = ffs(sbi->dir_per_block) - 1;
 691
 692         sbi->dir_start = sbi->fat_start + sbi->fats * sbi->fat_length;
 693         sbi->dir_entries =
 694                 CF_LE_W(get_unaligned((unsigned short *)&b->dir_entries));
 695         rootdir_sectors = sbi->dir_entries
 696                 * sizeof(struct msdos_dir_entry) / logical_sector_size;
 697         sbi->data_start = sbi->dir_start + rootdir_sectors;
 698         total_sectors = CF_LE_W(get_unaligned((unsigned short *)&b->sectors));
 699         if (total_sectors == 0)
 700                 total_sectors = CF_LE_L(b->total_sect);
 701         sbi->clusters = (total_sectors - sbi->data_start) / sbi->cluster_size;
 702
 703         error = 0;
 704         if (!error) {
 705                 sbi->fat_bits = fat32 ? 32 :
 706                         (fat ? fat :
 707                          (sbi->clusters > MSDOS_FAT12 ? 16 : 12));
 708                 fat_clusters =
 709                         sbi->fat_length * logical_sector_size * 8 / sbi->fat_bits;
 710                 error = !sbi->fats || (sbi->dir_entries & (sbi->dir_per_block - 1))
 711                         || sbi->clusters + 2 > fat_clusters + MSDOS_MAX_EXTRA
 712                         || logical_sector_size < 512
 713                         || PAGE_CACHE_SIZE < logical_sector_size
 714                         || !b->secs_track || !b->heads;
 715         }
 716         brelse(bh);
 717
 718         if (error)
 719                 goto out_invalid;
 720
 721         sb->s_blocksize = logical_sector_size;
 722         sb->s_blocksize_bits = ffs(logical_sector_size) - 1;
 723         set_blocksize(sb->s_dev, sb->s_blocksize);
 724         sbi->cvf_format = &default_cvf;
 725         if (!strcmp(cvf_format, "none"))
 726                 i = -1;
 727         else
 728                 i = detect_cvf(sb,cvf_format);
 729         if (i >= 0)
 730                 error = cvf_formats[i]->mount_cvf(sb, cvf_options);
 731         if (error || debug) {
 732                 /* The MSDOS_CAN_BMAP is obsolete, but left just to remember */
 733                 printk("[MS-DOS FS Rel. 12,FAT %d,check=%c,conv=%c,"
 734                        "uid=%d,gid=%d,umask=%03o%s]\n",
 735                        sbi->fat_bits,opts.name_check,
 736                        opts.conversion,opts.fs_uid,opts.fs_gid,opts.fs_umask,
 737                        MSDOS_CAN_BMAP(sbi) ? ",bmap" : "");
 738                 printk("[me=0x%x,cs=%d,#f=%d,fs=%d,fl=%ld,ds=%ld,de=%d,data=%ld,"
 739                        "se=%u,ts=%u,ls=%d,rc=%ld,fc=%u]\n",
 740                        b->media, sbi->cluster_size, sbi->fats,
 741                        sbi->fat_start, sbi->fat_length, sbi->dir_start,
 742                        sbi->dir_entries, sbi->data_start,
 743                        CF_LE_W(get_unaligned((unsigned short *)&b->sectors)),
 744                        CF_LE_L(b->total_sect), logical_sector_size,
 745                        sbi->root_cluster, sbi->free_clusters);
 746                 printk ("hard sector size = %d\n", hard_blksize);
 747         }
 748         if (i < 0)
 749                 if (sbi->clusters + 2 > fat_clusters)
 750                         sbi->clusters = fat_clusters - 2;
 751         if (error)
 752                 goto out_invalid;
 753
 754         sb->s_magic = MSDOS_SUPER_MAGIC;
 755         /* set up enough so that it can read an inode */
 756         init_MUTEX(&sbi->fat_lock);
 757         sbi->prev_free = 0;
 758
 759         cp = opts.codepage ? opts.codepage : 437;
 760         sprintf(buf, "cp%d", cp);
 761         sbi->nls_disk = load_nls(buf);
 762         if (! sbi->nls_disk) {
 763                 /* Fail only if explicit charset specified */
 764                 if (opts.codepage != 0)
 765                         goto out_fail;
 766                 sbi->options.codepage = 0; /* already 0?? */
 767                 sbi->nls_disk = load_nls_default();
 768         }
 769
 770         sbi->nls_io = NULL;
 771         if (sbi->options.isvfat && !opts.utf8) {
 772                 p = opts.iocharset ? opts.iocharset : CONFIG_NLS_DEFAULT;
 773                 sbi->nls_io = load_nls(p);
 774                 if (! sbi->nls_io)
 775                         /* Fail only if explicit charset specified */
 776                         if (opts.iocharset)
 777                                 goto out_unload_nls;
 778         }
 779         if (! sbi->nls_io)
 780                 sbi->nls_io = load_nls_default();
 781
 782         root_inode = new_inode(sb);
 783         if (!root_inode)
 784                 goto out_unload_nls;
 785         root_inode->i_ino = MSDOS_ROOT_INO;
 786         fat_read_root(root_inode);
 787         insert_inode_hash(root_inode);
 788         sb->s_root = d_alloc_root(root_inode);
 789         if (!sb->s_root)
 790                 goto out_no_root;
 791         if(i >= 0) {
 792                 sbi->cvf_format = cvf_formats[i];
 793                 ++cvf_format_use_count[i];
 794         }
 795         return sb;
 796
 797 out_no_root:
 798         printk("FAT: get root inode failed\n");
 799         iput(root_inode);
 800         unload_nls(sbi->nls_io);
 801 out_unload_nls:
 802         unload_nls(sbi->nls_disk);
 803         goto out_fail;
 804 out_invalid:
 805         if (!silent) {
 806                 printk("VFS: Can't find a valid FAT filesystem on dev %s.\n",
 807                         kdevname(sb->s_dev));
 808         }
 809 out_fail:
 810         if (opts.iocharset) {
 811                 printk("FAT: freeing iocharset=%s\n", opts.iocharset);
 812                 kfree(opts.iocharset);
 813         }
 814         if(sbi->private_data)
 815                 kfree(sbi->private_data);
 816         sbi->private_data = NULL;
 817
 818         return NULL;
 819 }
 820
 821 int fat_statfs(struct super_block *sb,struct statfs *buf)
 822 {
 823         int free,nr;
 824
 825         if (MSDOS_SB(sb)->cvf_format &&
 826             MSDOS_SB(sb)->cvf_format->cvf_statfs)
 827                 return MSDOS_SB(sb)->cvf_format->cvf_statfs(sb,buf,
 828                                                 sizeof(struct statfs));
 829
 830         lock_fat(sb);
 831         if (MSDOS_SB(sb)->free_clusters != -1)
 832                 free = MSDOS_SB(sb)->free_clusters;
 833         else {
 834                 free = 0;
 835                 for (nr = 2; nr < MSDOS_SB(sb)->clusters+2; nr++)
 836                         if (!fat_access(sb,nr,-1)) free++;
 837                 MSDOS_SB(sb)->free_clusters = free;
 838         }
 839         unlock_fat(sb);
 840         buf->f_type = sb->s_magic;
 841         buf->f_bsize = 1 << MSDOS_SB(sb)->cluster_bits;
 842         buf->f_blocks = MSDOS_SB(sb)->clusters;
 843         buf->f_bfree = free;
 844         buf->f_bavail = free;
 845         buf->f_namelen = MSDOS_SB(sb)->options.isvfat ? 260 : 12;
 846         return 0;
 847 }
 848
 849 static int is_exec(char *extension)
 850 {
 851         char *exe_extensions = "EXECOMBAT", *walk;
 852
 853         for (walk = exe_extensions; *walk; walk += 3)
 854                 if (!strncmp(extension, walk, 3))
 855                         return 1;
 856         return 0;
 857 }
 858
 859 static int fat_writepage(struct page *page)
 860 {
 861         return block_write_full_page(page,fat_get_block);
 862 }
 863 static int fat_readpage(struct file *file, struct page *page)
 864 {
 865         return block_read_full_page(page,fat_get_block);
 866 }
 867 static int fat_prepare_write(struct file *file, struct page *page, unsigned from, unsigned to)
 868 {
 869         return cont_prepare_write(page,from,to,fat_get_block,
 870                 &MSDOS_I(page->mapping->host)->mmu_private);
 871 }
 872 static int _fat_bmap(struct address_space *mapping, long block)
 873 {
 874         return generic_block_bmap(mapping,block,fat_get_block);
 875 }
 876 static struct address_space_operations fat_aops = {
 877         readpage: fat_readpage,
 878         writepage: fat_writepage,
 879         sync_page: block_sync_page,
 880         prepare_write: fat_prepare_write,
 881         commit_write: generic_commit_write,
 882         bmap: _fat_bmap
 883 };
 884
 885 /* doesn't deal with root inode */
 886 static void fat_fill_inode(struct inode *inode, struct msdos_dir_entry *de)
 887 {
 888         struct super_block *sb = inode->i_sb;
 889         struct msdos_sb_info *sbi = MSDOS_SB(sb);
 890         int nr;
 891
 892         INIT_LIST_HEAD(&MSDOS_I(inode)->i_fat_hash);
 893         MSDOS_I(inode)->i_location = 0;
 894         MSDOS_I(inode)->i_fat_inode = inode;
 895         inode->i_uid = sbi->options.fs_uid;
 896         inode->i_gid = sbi->options.fs_gid;
 897         inode->i_version = ++event;
 898         inode->i_generation = CURRENT_TIME;
 899
 900         if ((de->attr & ATTR_DIR) && !IS_FREE(de->name)) {
 901                 inode->i_generation &= ~1;
 902                 inode->i_mode = MSDOS_MKMODE(de->attr,S_IRWXUGO &
 903                     ~sbi->options.fs_umask) | S_IFDIR;
 904                 inode->i_op = sbi->dir_ops;
 905                 inode->i_fop = &fat_dir_operations;
 906
 907                 MSDOS_I(inode)->i_start = CF_LE_W(de->start);
 908                 if (sbi->fat_bits == 32) {
 909                         MSDOS_I(inode)->i_start |=
 910                                 (CF_LE_W(de->starthi) << 16);
 911                 }
 912                 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 913                 inode->i_nlink = fat_subdirs(inode);
 914                     /* includes .., compensating for "self" */
 915 #ifdef DEBUG
 916                 if (!inode->i_nlink) {
 917                         printk("directory %d: i_nlink == 0\n",inode->i_ino);
 918                         inode->i_nlink = 1;
 919                 }
 920 #endif
 921                 if ((nr = MSDOS_I(inode)->i_start) != 0)
 922                         while (nr != -1) {
 923                                 inode->i_size += 1 << sbi->cluster_bits;
 924                                 if (!(nr = fat_access(sb, nr, -1))) {
 925                                         printk("Directory %ld: bad FAT\n",
 926                                             inode->i_ino);
 927                                         break;
 928                                 }
 929                         }
 930                 MSDOS_I(inode)->mmu_private = inode->i_size;
 931         } else { /* not a directory */
 932                 inode->i_generation |= 1;
 933                 inode->i_mode = MSDOS_MKMODE(de->attr,
 934                     ((sbi->options.showexec &&
 935                        !is_exec(de->ext))
 936                         ? S_IRUGO|S_IWUGO : S_IRWXUGO)
 937                     & ~sbi->options.fs_umask) | S_IFREG;
 938                 MSDOS_I(inode)->i_start = CF_LE_W(de->start);
 939                 if (sbi->fat_bits == 32) {
 940                         MSDOS_I(inode)->i_start |=
 941                                 (CF_LE_W(de->starthi) << 16);
 942                 }
 943                 MSDOS_I(inode)->i_logstart = MSDOS_I(inode)->i_start;
 944                 inode->i_size = CF_LE_L(de->size);
 945                 inode->i_op = &fat_file_inode_operations;
 946                 inode->i_fop = &fat_file_operations;
 947                 inode->i_mapping->a_ops = &fat_aops;
 948                 MSDOS_I(inode)->mmu_private = inode->i_size;
 949         }
 950         if(de->attr & ATTR_SYS)
 951                 if (sbi->options.sys_immutable)
 952                         inode->i_flags |= S_IMMUTABLE;
 953         MSDOS_I(inode)->i_attrs = de->attr & ATTR_UNUSED;
 954         /* this is as close to the truth as we can get ... */
 955         inode->i_blksize = 1 << sbi->cluster_bits;
 956         inode->i_blocks = ((inode->i_size + inode->i_blksize - 1)
 957                            & ~(inode->i_blksize - 1)) >> 9;
 958         inode->i_mtime = inode->i_atime =
 959                 date_dos2unix(CF_LE_W(de->time),CF_LE_W(de->date));
 960         inode->i_ctime =
 961                 MSDOS_SB(sb)->options.isvfat
 962                 ? date_dos2unix(CF_LE_W(de->ctime),CF_LE_W(de->cdate))
 963                 : inode->i_mtime;
 964         MSDOS_I(inode)->i_ctime_ms = de->ctime_ms;
 965 }
 966
 967 void fat_write_inode(struct inode *inode, int wait)
 968 {
 969         struct super_block *sb = inode->i_sb;
 970         struct buffer_head *bh;
 971         struct msdos_dir_entry *raw_entry;
 972         unsigned int i_pos;
 973
 974 retry:
 975         i_pos = MSDOS_I(inode)->i_location;
 976         if (inode->i_ino == MSDOS_ROOT_INO || !i_pos) {
 977                 return;
 978         }
 979         lock_kernel();
 980         if (!(bh = fat_bread(sb, i_pos >> MSDOS_SB(sb)->dir_per_block_bits))) {
 981                 printk("dev = %s, ino = %d\n", kdevname(inode->i_dev), i_pos);
 982                 fat_fs_panic(sb, "msdos_write_inode: unable to read i-node block");
 983                 unlock_kernel();
 984                 return;
 985         }
 986         spin_lock(&fat_inode_lock);
 987         if (i_pos != MSDOS_I(inode)->i_location) {
 988                 spin_unlock(&fat_inode_lock);
 989                 fat_brelse(sb, bh);
 990                 unlock_kernel();
 991                 goto retry;
 992         }
 993
 994         raw_entry = &((struct msdos_dir_entry *) (bh->b_data))
 995             [i_pos & (MSDOS_SB(sb)->dir_per_block - 1)];
 996         if (S_ISDIR(inode->i_mode)) {
 997                 raw_entry->attr = ATTR_DIR;
 998                 raw_entry->size = 0;
 999         }
1000         else {
1001                 raw_entry->attr = ATTR_NONE;
1002                 raw_entry->size = CT_LE_L(inode->i_size);
1003         }
1004         raw_entry->attr |= MSDOS_MKATTR(inode->i_mode) |
1005             MSDOS_I(inode)->i_attrs;
1006         raw_entry->start = CT_LE_W(MSDOS_I(inode)->i_logstart);
1007         raw_entry->starthi = CT_LE_W(MSDOS_I(inode)->i_logstart >> 16);
1008         fat_date_unix2dos(inode->i_mtime,&raw_entry->time,&raw_entry->date);
1009         raw_entry->time = CT_LE_W(raw_entry->time);
1010         raw_entry->date = CT_LE_W(raw_entry->date);
1011         if (MSDOS_SB(sb)->options.isvfat) {
1012                 fat_date_unix2dos(inode->i_ctime,&raw_entry->ctime,&raw_entry->cdate);
1013                 raw_entry->ctime_ms = MSDOS_I(inode)->i_ctime_ms;
1014                 raw_entry->ctime = CT_LE_W(raw_entry->ctime);
1015                 raw_entry->cdate = CT_LE_W(raw_entry->cdate);
1016         }
1017         spin_unlock(&fat_inode_lock);
1018         fat_mark_buffer_dirty(sb, bh);
1019         fat_brelse(sb, bh);
1020         unlock_kernel();
1021 }
1022
1023
1024 int fat_notify_change(struct dentry * dentry, struct iattr * attr)
1025 {
1026         struct super_block *sb = dentry->d_sb;
1027         struct inode *inode = dentry->d_inode;
1028         int error;
1029
1030         /* FAT cannot truncate to a longer file */
1031         if (attr->ia_valid & ATTR_SIZE) {
1032                 if (attr->ia_size > inode->i_size)
1033                         return -EPERM;
1034         }
1035
1036         error = inode_change_ok(inode, attr);
1037         if (error)
1038                 return MSDOS_SB(sb)->options.quiet ? 0 : error;
1039
1040         if (((attr->ia_valid & ATTR_UID) &&
1041              (attr->ia_uid != MSDOS_SB(sb)->options.fs_uid)) ||
1042             ((attr->ia_valid & ATTR_GID) &&
1043              (attr->ia_gid != MSDOS_SB(sb)->options.fs_gid)) ||
1044             ((attr->ia_valid & ATTR_MODE) &&
1045              (attr->ia_mode & ~MSDOS_VALID_MODE)))
1046                 error = -EPERM;
1047
1048         if (error)
1049                 return MSDOS_SB(sb)->options.quiet ? 0 : error;
1050
1051         error = inode_setattr(inode, attr);
1052         if (error)
1053                 return error;
1054
1055         if (S_ISDIR(inode->i_mode))
1056                 inode->i_mode |= S_IXUGO;
1057
1058         inode->i_mode = ((inode->i_mode & S_IFMT) | ((((inode->i_mode & S_IRWXU
1059             & ~MSDOS_SB(sb)->options.fs_umask) | S_IRUSR) >> 6)*S_IXUGO)) &
1060             ~MSDOS_SB(sb)->options.fs_umask;
1061         return 0;
1062 }
1063 MODULE_LICENSE("GPL");