fs/ext2/super.c

   1 /*
   2  *  linux/fs/ext2/super.c
   3  *
   4  * Copyright (C) 1992, 1993, 1994, 1995
   5  * Remy Card (card@masi.ibp.fr)
   6  * Laboratoire MASI - Institut Blaise Pascal
   7  * Universite Pierre et Marie Curie (Paris VI)
   8  *
   9  *  from
  10  *
  11  *  linux/fs/minix/inode.c
  12  *
  13  *  Copyright (C) 1991, 1992  Linus Torvalds
  14  *
  15  *  Big-endian to little-endian byte-swapping/bitmaps by
  16  *        David S. Miller (davem@caip.rutgers.edu), 1995
  17  */
  18
  19 #include <linux/config.h>
  20 #include <linux/module.h>
  21 #include <linux/string.h>
  22 #include <linux/fs.h>
  23 #include <linux/ext2_fs.h>
  24 #include <linux/slab.h>
  25 #include <linux/init.h>
  26 #include <linux/locks.h>
  27 #include <linux/blkdev.h>
  28 #include <asm/uaccess.h>
  29
  30
  31 static void ext2_sync_super(struct super_block *sb,
  32                             struct ext2_super_block *es);
  33
  34 static char error_buf[1024];
  35
  36 void ext2_error (struct super_block * sb, const char * function,
  37                  const char * fmt, ...)
  38 {
  39         va_list args;
  40         struct ext2_super_block *es = EXT2_SB(sb)->s_es;
  41
  42         if (!(sb->s_flags & MS_RDONLY)) {
  43                 sb->u.ext2_sb.s_mount_state |= EXT2_ERROR_FS;
  44                 es->s_state =
  45                         cpu_to_le16(le16_to_cpu(es->s_state) | EXT2_ERROR_FS);
  46                 ext2_sync_super(sb, es);
  47         }
  48         va_start (args, fmt);
  49         vsprintf (error_buf, fmt, args);
  50         va_end (args);
  51         if (test_opt (sb, ERRORS_PANIC) ||
  52             (le16_to_cpu(sb->u.ext2_sb.s_es->s_errors) == EXT2_ERRORS_PANIC &&
  53              !test_opt (sb, ERRORS_CONT) && !test_opt (sb, ERRORS_RO)))
  54                 panic ("EXT2-fs panic (device %s): %s: %s\n",
  55                        bdevname(sb->s_dev), function, error_buf);
  56         printk (KERN_CRIT "EXT2-fs error (device %s): %s: %s\n",
  57                 bdevname(sb->s_dev), function, error_buf);
  58         if (test_opt (sb, ERRORS_RO) ||
  59             (le16_to_cpu(sb->u.ext2_sb.s_es->s_errors) == EXT2_ERRORS_RO &&
  60              !test_opt (sb, ERRORS_CONT) && !test_opt (sb, ERRORS_PANIC))) {
  61                 printk ("Remounting filesystem read-only\n");
  62                 sb->s_flags |= MS_RDONLY;
  63         }
  64 }
  65
  66 NORET_TYPE void ext2_panic (struct super_block * sb, const char * function,
  67                             const char * fmt, ...)
  68 {
  69         va_list args;
  70
  71         if (!(sb->s_flags & MS_RDONLY)) {
  72                 sb->u.ext2_sb.s_mount_state |= EXT2_ERROR_FS;
  73                 sb->u.ext2_sb.s_es->s_state =
  74                         cpu_to_le16(le16_to_cpu(sb->u.ext2_sb.s_es->s_state) | EXT2_ERROR_FS);
  75                 mark_buffer_dirty(sb->u.ext2_sb.s_sbh);
  76                 sb->s_dirt = 1;
  77         }
  78         va_start (args, fmt);
  79         vsprintf (error_buf, fmt, args);
  80         va_end (args);
  81         sb->s_flags |= MS_RDONLY;
  82         panic ("EXT2-fs panic (device %s): %s: %s\n",
  83                bdevname(sb->s_dev), function, error_buf);
  84 }
  85
  86 void ext2_warning (struct super_block * sb, const char * function,
  87                    const char * fmt, ...)
  88 {
  89         va_list args;
  90
  91         va_start (args, fmt);
  92         vsprintf (error_buf, fmt, args);
  93         va_end (args);
  94         printk (KERN_WARNING "EXT2-fs warning (device %s): %s: %s\n",
  95                 bdevname(sb->s_dev), function, error_buf);
  96 }
  97
  98 void ext2_update_dynamic_rev(struct super_block *sb)
  99 {
 100         struct ext2_super_block *es = EXT2_SB(sb)->s_es;
 101
 102         if (le32_to_cpu(es->s_rev_level) > EXT2_GOOD_OLD_REV)
 103                 return;
 104
 105         ext2_warning(sb, __FUNCTION__,
 106                      "updating to rev %d because of new feature flag, "
 107                      "running e2fsck is recommended",
 108                      EXT2_DYNAMIC_REV);
 109
 110         es->s_first_ino = cpu_to_le32(EXT2_GOOD_OLD_FIRST_INO);
 111         es->s_inode_size = cpu_to_le16(EXT2_GOOD_OLD_INODE_SIZE);
 112         es->s_rev_level = cpu_to_le32(EXT2_DYNAMIC_REV);
 113         /* leave es->s_feature_*compat flags alone */
 114         /* es->s_uuid will be set by e2fsck if empty */
 115
 116         /*
 117          * The rest of the superblock fields should be zero, and if not it
 118          * means they are likely already in use, so leave them alone.  We
 119          * can leave it up to e2fsck to clean up any inconsistencies there.
 120          */
 121 }
 122
 123 void ext2_put_super (struct super_block * sb)
 124 {
 125         int db_count;
 126         int i;
 127
 128         if (!(sb->s_flags & MS_RDONLY)) {
 129                 struct ext2_super_block *es = EXT2_SB(sb)->s_es;
 130
 131                 es->s_state = le16_to_cpu(EXT2_SB(sb)->s_mount_state);
 132                 ext2_sync_super(sb, es);
 133         }
 134         db_count = EXT2_SB(sb)->s_gdb_count;
 135         for (i = 0; i < db_count; i++)
 136                 if (sb->u.ext2_sb.s_group_desc[i])
 137                         brelse (sb->u.ext2_sb.s_group_desc[i]);
 138         kfree(sb->u.ext2_sb.s_group_desc);
 139         for (i = 0; i < EXT2_MAX_GROUP_LOADED; i++)
 140                 if (sb->u.ext2_sb.s_inode_bitmap[i])
 141                         brelse (sb->u.ext2_sb.s_inode_bitmap[i]);
 142         for (i = 0; i < EXT2_MAX_GROUP_LOADED; i++)
 143                 if (sb->u.ext2_sb.s_block_bitmap[i])
 144                         brelse (sb->u.ext2_sb.s_block_bitmap[i]);
 145         brelse (sb->u.ext2_sb.s_sbh);
 146
 147         return;
 148 }
 149
 150 static struct super_operations ext2_sops = {
 151         read_inode:     ext2_read_inode,
 152         write_inode:    ext2_write_inode,
 153         put_inode:      ext2_put_inode,
 154         delete_inode:   ext2_delete_inode,
 155         put_super:      ext2_put_super,
 156         write_super:    ext2_write_super,
 157         statfs:         ext2_statfs,
 158         remount_fs:     ext2_remount,
 159 };
 160
 161 /*
 162  * This function has been shamelessly adapted from the msdos fs
 163  */
 164 static int parse_options (char * options, unsigned long * sb_block,
 165                           unsigned short *resuid, unsigned short * resgid,
 166                           unsigned long * mount_options)
 167 {
 168         char * this_char;
 169         char * value;
 170
 171         if (!options)
 172                 return 1;
 173         for (this_char = strtok (options, ",");
 174              this_char != NULL;
 175              this_char = strtok (NULL, ",")) {
 176                 if ((value = strchr (this_char, '=')) != NULL)
 177                         *value++ = 0;
 178                 if (!strcmp (this_char, "bsddf"))
 179                         clear_opt (*mount_options, MINIX_DF);
 180                 else if (!strcmp (this_char, "nouid32")) {
 181                         set_opt (*mount_options, NO_UID32);
 182                 }
 183                 else if (!strcmp (this_char, "check")) {
 184                         if (!value || !*value || !strcmp (value, "none"))
 185                                 clear_opt (*mount_options, CHECK);
 186                         else
 187 #ifdef CONFIG_EXT2_CHECK
 188                                 set_opt (*mount_options, CHECK);
 189 #else
 190                                 printk("EXT2 Check option not supported\n");
 191 #endif
 192                 }
 193                 else if (!strcmp (this_char, "debug"))
 194                         set_opt (*mount_options, DEBUG);
 195                 else if (!strcmp (this_char, "errors")) {
 196                         if (!value || !*value) {
 197                                 printk ("EXT2-fs: the errors option requires "
 198                                         "an argument\n");
 199                                 return 0;
 200                         }
 201                         if (!strcmp (value, "continue")) {
 202                                 clear_opt (*mount_options, ERRORS_RO);
 203                                 clear_opt (*mount_options, ERRORS_PANIC);
 204                                 set_opt (*mount_options, ERRORS_CONT);
 205                         }
 206                         else if (!strcmp (value, "remount-ro")) {
 207                                 clear_opt (*mount_options, ERRORS_CONT);
 208                                 clear_opt (*mount_options, ERRORS_PANIC);
 209                                 set_opt (*mount_options, ERRORS_RO);
 210                         }
 211                         else if (!strcmp (value, "panic")) {
 212                                 clear_opt (*mount_options, ERRORS_CONT);
 213                                 clear_opt (*mount_options, ERRORS_RO);
 214                                 set_opt (*mount_options, ERRORS_PANIC);
 215                         }
 216                         else {
 217                                 printk ("EXT2-fs: Invalid errors option: %s\n",
 218                                         value);
 219                                 return 0;
 220                         }
 221                 }
 222                 else if (!strcmp (this_char, "grpid") ||
 223                          !strcmp (this_char, "bsdgroups"))
 224                         set_opt (*mount_options, GRPID);
 225                 else if (!strcmp (this_char, "minixdf"))
 226                         set_opt (*mount_options, MINIX_DF);
 227                 else if (!strcmp (this_char, "nocheck"))
 228                         clear_opt (*mount_options, CHECK);
 229                 else if (!strcmp (this_char, "nogrpid") ||
 230                          !strcmp (this_char, "sysvgroups"))
 231                         clear_opt (*mount_options, GRPID);
 232                 else if (!strcmp (this_char, "resgid")) {
 233                         if (!value || !*value) {
 234                                 printk ("EXT2-fs: the resgid option requires "
 235                                         "an argument\n");
 236                                 return 0;
 237                         }
 238                         *resgid = simple_strtoul (value, &value, 0);
 239                         if (*value) {
 240                                 printk ("EXT2-fs: Invalid resgid option: %s\n",
 241                                         value);
 242                                 return 0;
 243                         }
 244                 }
 245                 else if (!strcmp (this_char, "resuid")) {
 246                         if (!value || !*value) {
 247                                 printk ("EXT2-fs: the resuid option requires "
 248                                         "an argument");
 249                                 return 0;
 250                         }
 251                         *resuid = simple_strtoul (value, &value, 0);
 252                         if (*value) {
 253                                 printk ("EXT2-fs: Invalid resuid option: %s\n",
 254                                         value);
 255                                 return 0;
 256                         }
 257                 }
 258                 else if (!strcmp (this_char, "sb")) {
 259                         if (!value || !*value) {
 260                                 printk ("EXT2-fs: the sb option requires "
 261                                         "an argument");
 262                                 return 0;
 263                         }
 264                         *sb_block = simple_strtoul (value, &value, 0);
 265                         if (*value) {
 266                                 printk ("EXT2-fs: Invalid sb option: %s\n",
 267                                         value);
 268                                 return 0;
 269                         }
 270                 }
 271                 /* Silently ignore the quota options */
 272                 else if (!strcmp (this_char, "grpquota")
 273                          || !strcmp (this_char, "noquota")
 274                          || !strcmp (this_char, "quota")
 275                          || !strcmp (this_char, "usrquota"))
 276                         /* Don't do anything ;-) */ ;
 277                 else {
 278                         printk ("EXT2-fs: Unrecognized mount option %s\n", this_char);
 279                         return 0;
 280                 }
 281         }
 282         return 1;
 283 }
 284
 285 static int ext2_setup_super (struct super_block * sb,
 286                               struct ext2_super_block * es,
 287                               int read_only)
 288 {
 289         int res = 0;
 290         if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
 291                 printk ("EXT2-fs warning: revision level too high, "
 292                         "forcing read-only mode\n");
 293                 res = MS_RDONLY;
 294         }
 295         if (read_only)
 296                 return res;
 297         if (!(sb->u.ext2_sb.s_mount_state & EXT2_VALID_FS))
 298                 printk ("EXT2-fs warning: mounting unchecked fs, "
 299                         "running e2fsck is recommended\n");
 300         else if ((sb->u.ext2_sb.s_mount_state & EXT2_ERROR_FS))
 301                 printk ("EXT2-fs warning: mounting fs with errors, "
 302                         "running e2fsck is recommended\n");
 303         else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
 304                  le16_to_cpu(es->s_mnt_count) >=
 305                  (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
 306                 printk ("EXT2-fs warning: maximal mount count reached, "
 307                         "running e2fsck is recommended\n");
 308         else if (le32_to_cpu(es->s_checkinterval) &&
 309                 (le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= CURRENT_TIME))
 310                 printk ("EXT2-fs warning: checktime reached, "
 311                         "running e2fsck is recommended\n");
 312         if (!(__s16) le16_to_cpu(es->s_max_mnt_count))
 313                 es->s_max_mnt_count = (__s16) cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
 314         es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
 315         ext2_write_super(sb);
 316         if (test_opt (sb, DEBUG))
 317                 printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
 318                         "bpg=%lu, ipg=%lu, mo=%04lx]\n",
 319                         EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
 320                         sb->u.ext2_sb.s_frag_size,
 321                         sb->u.ext2_sb.s_groups_count,
 322                         EXT2_BLOCKS_PER_GROUP(sb),
 323                         EXT2_INODES_PER_GROUP(sb),
 324                         sb->u.ext2_sb.s_mount_opt);
 325 #ifdef CONFIG_EXT2_CHECK
 326         if (test_opt (sb, CHECK)) {
 327                 ext2_check_blocks_bitmap (sb);
 328                 ext2_check_inodes_bitmap (sb);
 329         }
 330 #endif
 331         return res;
 332 }
 333
 334 static int ext2_check_descriptors (struct super_block * sb)
 335 {
 336         int i;
 337         int desc_block = 0;
 338         unsigned long block = le32_to_cpu(sb->u.ext2_sb.s_es->s_first_data_block);
 339         struct ext2_group_desc * gdp = NULL;
 340
 341         ext2_debug ("Checking group descriptors");
 342
 343         for (i = 0; i < sb->u.ext2_sb.s_groups_count; i++)
 344         {
 345                 if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
 346                         gdp = (struct ext2_group_desc *) sb->u.ext2_sb.s_group_desc[desc_block++]->b_data;
 347                 if (le32_to_cpu(gdp->bg_block_bitmap) < block ||
 348                     le32_to_cpu(gdp->bg_block_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
 349                 {
 350                         ext2_error (sb, "ext2_check_descriptors",
 351                                     "Block bitmap for group %d"
 352                                     " not in group (block %lu)!",
 353                                     i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
 354                         return 0;
 355                 }
 356                 if (le32_to_cpu(gdp->bg_inode_bitmap) < block ||
 357                     le32_to_cpu(gdp->bg_inode_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
 358                 {
 359                         ext2_error (sb, "ext2_check_descriptors",
 360                                     "Inode bitmap for group %d"
 361                                     " not in group (block %lu)!",
 362                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_bitmap));
 363                         return 0;
 364                 }
 365                 if (le32_to_cpu(gdp->bg_inode_table) < block ||
 366                     le32_to_cpu(gdp->bg_inode_table) + sb->u.ext2_sb.s_itb_per_group >=
 367                     block + EXT2_BLOCKS_PER_GROUP(sb))
 368                 {
 369                         ext2_error (sb, "ext2_check_descriptors",
 370                                     "Inode table for group %d"
 371                                     " not in group (block %lu)!",
 372                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
 373                         return 0;
 374                 }
 375                 block += EXT2_BLOCKS_PER_GROUP(sb);
 376                 gdp++;
 377         }
 378         return 1;
 379 }
 380
 381 #define log2(n) ffz(~(n))
 382
 383 /*
 384  * Maximal file size.  There is a direct, and {,double-,triple-}indirect
 385  * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
 386  * We need to be 1 filesystem block less than the 2^32 sector limit.
 387  */
 388 static loff_t ext2_max_size(int bits)
 389 {
 390         loff_t res = EXT2_NDIR_BLOCKS;
 391         res += 1LL << (bits-2);
 392         res += 1LL << (2*(bits-2));
 393         res += 1LL << (3*(bits-2));
 394         res <<= bits;
 395         if (res > (512LL << 32) - (1 << bits))
 396                 res = (512LL << 32) - (1 << bits);
 397         return res;
 398 }
 399
 400 static unsigned long descriptor_loc(struct super_block *sb,
 401                                     unsigned long logic_sb_block,
 402                                     int nr)
 403 {
 404         struct ext2_sb_info *sbi = EXT2_SB(sb);
 405         unsigned long bg, first_data_block, first_meta_bg;
 406         int has_super = 0;
 407
 408         first_data_block = le32_to_cpu(sbi->s_es->s_first_data_block);
 409         first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
 410
 411         if (!EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_META_BG) ||
 412             nr < first_meta_bg)
 413                 return (logic_sb_block + nr + 1);
 414         bg = sbi->s_desc_per_block * nr;
 415         if (ext2_bg_has_super(sb, bg))
 416                 has_super = 1;
 417         return (first_data_block + has_super + (bg * sbi->s_blocks_per_group));
 418 }
 419
 420 struct super_block * ext2_read_super (struct super_block * sb, void * data,
 421                                       int silent)
 422 {
 423         struct buffer_head * bh;
 424         struct ext2_sb_info * sbi = EXT2_SB(sb);
 425         struct ext2_super_block * es;
 426         unsigned long sb_block = 1;
 427         unsigned short resuid = EXT2_DEF_RESUID;
 428         unsigned short resgid = EXT2_DEF_RESGID;
 429         unsigned long block;
 430         unsigned long logic_sb_block;
 431         unsigned long offset = 0;
 432         kdev_t dev = sb->s_dev;
 433         int blocksize = BLOCK_SIZE;
 434         int db_count;
 435         int i, j;
 436
 437         /*
 438          * See what the current blocksize for the device is, and
 439          * use that as the blocksize.  Otherwise (or if the blocksize
 440          * is smaller than the default) use the default.
 441          * This is important for devices that have a hardware
 442          * sectorsize that is larger than the default.
 443          */
 444         blocksize = get_hardsect_size(dev);
 445         if(blocksize < BLOCK_SIZE )
 446             blocksize = BLOCK_SIZE;
 447
 448         sb->u.ext2_sb.s_mount_opt = 0;
 449         if (!parse_options ((char *) data, &sb_block, &resuid, &resgid,
 450             &sb->u.ext2_sb.s_mount_opt)) {
 451                 return NULL;
 452         }
 453
 454         if (set_blocksize(dev, blocksize) < 0) {
 455                 printk ("EXT2-fs: unable to set blocksize %d\n", blocksize);
 456                 return NULL;
 457         }
 458         sb->s_blocksize = blocksize;
 459
 460         /*
 461          * If the superblock doesn't start on a sector boundary,
 462          * calculate the offset.  FIXME(eric) this doesn't make sense
 463          * that we would have to do this.
 464          */
 465         if (blocksize != BLOCK_SIZE) {
 466                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 467                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 468         } else {
 469                 logic_sb_block = sb_block;
 470         }
 471
 472         if (!(bh = sb_bread(sb, logic_sb_block))) {
 473                 printk ("EXT2-fs: unable to read superblock\n");
 474                 return NULL;
 475         }
 476         /*
 477          * Note: s_es must be initialized as soon as possible because
 478          *       some ext2 macro-instructions depend on its value
 479          */
 480         es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 481         sb->u.ext2_sb.s_es = es;
 482         sb->s_magic = le16_to_cpu(es->s_magic);
 483         if (sb->s_magic != EXT2_SUPER_MAGIC)
 484                 goto cantfind_ext2;
 485         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
 486             (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
 487              EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
 488              EXT2_HAS_INCOMPAT_FEATURE(sb, ~0U)))
 489                 printk("EXT2-fs warning: feature flags set on rev 0 fs, "
 490                        "running e2fsck is recommended\n");
 491         /*
 492          * Check feature flags regardless of the revision level, since we
 493          * previously didn't change the revision level when setting the flags,
 494          * so there is a chance incompat flags are set on a rev 0 filesystem.
 495          */
 496         if ((i = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP))) {
 497                 printk("EXT2-fs: %s: couldn't mount because of "
 498                        "unsupported optional features (%x).\n",
 499                        bdevname(dev), i);
 500                 goto failed_mount;
 501         }
 502         if (!(sb->s_flags & MS_RDONLY) &&
 503             (i = EXT2_HAS_RO_COMPAT_FEATURE(sb, ~EXT2_FEATURE_RO_COMPAT_SUPP))){
 504                 printk("EXT2-fs: %s: couldn't mount RDWR because of "
 505                        "unsupported optional features (%x).\n",
 506                        bdevname(dev), i);
 507                 goto failed_mount;
 508         }
 509         if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
 510                 ext2_warning(sb, __FUNCTION__,
 511                         "mounting ext3 filesystem as ext2\n");
 512         sb->s_blocksize_bits =
 513                 le32_to_cpu(EXT2_SB(sb)->s_es->s_log_block_size) + 10;
 514         sb->s_blocksize = 1 << sb->s_blocksize_bits;
 515
 516         sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);
 517
 518         /* If the blocksize doesn't match, re-read the thing.. */
 519         if (sb->s_blocksize != blocksize) {
 520                 blocksize = sb->s_blocksize;
 521                 brelse(bh);
 522
 523                 if (set_blocksize(dev, blocksize) < 0) {
 524                         printk(KERN_ERR "EXT2-fs: blocksize too small for device.\n");
 525                         return NULL;
 526                 }
 527
 528                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 529                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 530                 bh = sb_bread(sb, logic_sb_block);
 531                 if(!bh) {
 532                         printk("EXT2-fs: Couldn't read superblock on "
 533                                "2nd try.\n");
 534                         goto failed_mount;
 535                 }
 536                 es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 537                 sb->u.ext2_sb.s_es = es;
 538                 if (es->s_magic != le16_to_cpu(EXT2_SUPER_MAGIC)) {
 539                         printk ("EXT2-fs: Magic mismatch, very weird !\n");
 540                         goto failed_mount;
 541                 }
 542         }
 543
 544         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
 545                 sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
 546                 sbi->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
 547         } else {
 548                 sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
 549                 sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
 550                 if ((sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
 551                     (sbi->s_inode_size & (sbi->s_inode_size - 1)) ||
 552                     (sbi->s_inode_size > blocksize)) {
 553                         printk ("EXT2-fs: unsupported inode size: %d\n",
 554                                 sbi->s_inode_size);
 555                         goto failed_mount;
 556                 }
 557         }
 558         sb->u.ext2_sb.s_frag_size = EXT2_MIN_FRAG_SIZE <<
 559                                    le32_to_cpu(es->s_log_frag_size);
 560         if (sb->u.ext2_sb.s_frag_size == 0)
 561                 goto cantfind_ext2;
 562         sb->u.ext2_sb.s_frags_per_block = sb->s_blocksize /
 563                                           sb->u.ext2_sb.s_frag_size;
 564         sb->u.ext2_sb.s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
 565         sb->u.ext2_sb.s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
 566         sb->u.ext2_sb.s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
 567         if (EXT2_INODE_SIZE(sb) == 0)
 568                 goto cantfind_ext2;
 569         sb->u.ext2_sb.s_inodes_per_block = sb->s_blocksize /
 570                                            EXT2_INODE_SIZE(sb);
 571         if (sb->u.ext2_sb.s_inodes_per_block == 0)
 572                 goto cantfind_ext2;
 573         sb->u.ext2_sb.s_itb_per_group = sb->u.ext2_sb.s_inodes_per_group /
 574                                         sb->u.ext2_sb.s_inodes_per_block;
 575         sb->u.ext2_sb.s_desc_per_block = sb->s_blocksize /
 576                                          sizeof (struct ext2_group_desc);
 577         sb->u.ext2_sb.s_sbh = bh;
 578         if (resuid != EXT2_DEF_RESUID)
 579                 sb->u.ext2_sb.s_resuid = resuid;
 580         else
 581                 sb->u.ext2_sb.s_resuid = le16_to_cpu(es->s_def_resuid);
 582         if (resgid != EXT2_DEF_RESGID)
 583                 sb->u.ext2_sb.s_resgid = resgid;
 584         else
 585                 sb->u.ext2_sb.s_resgid = le16_to_cpu(es->s_def_resgid);
 586         sb->u.ext2_sb.s_mount_state = le16_to_cpu(es->s_state);
 587         sb->u.ext2_sb.s_addr_per_block_bits =
 588                 log2 (EXT2_ADDR_PER_BLOCK(sb));
 589         sb->u.ext2_sb.s_desc_per_block_bits =
 590                 log2 (EXT2_DESC_PER_BLOCK(sb));
 591
 592         if (sb->s_magic != EXT2_SUPER_MAGIC)
 593                 goto cantfind_ext2;
 594
 595         if (sb->s_blocksize != bh->b_size) {
 596                 if (!silent)
 597                         printk ("VFS: Unsupported blocksize on dev "
 598                                 "%s.\n", bdevname(dev));
 599                 goto failed_mount;
 600         }
 601
 602         if (sb->s_blocksize != sb->u.ext2_sb.s_frag_size) {
 603                 printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
 604                         sb->u.ext2_sb.s_frag_size, sb->s_blocksize);
 605                 goto failed_mount;
 606         }
 607
 608         if (sb->u.ext2_sb.s_blocks_per_group > sb->s_blocksize * 8) {
 609                 printk ("EXT2-fs: #blocks per group too big: %lu\n",
 610                         sb->u.ext2_sb.s_blocks_per_group);
 611                 goto failed_mount;
 612         }
 613         if (sb->u.ext2_sb.s_frags_per_group > sb->s_blocksize * 8) {
 614                 printk ("EXT2-fs: #fragments per group too big: %lu\n",
 615                         sb->u.ext2_sb.s_frags_per_group);
 616                 goto failed_mount;
 617         }
 618         if (sb->u.ext2_sb.s_inodes_per_group > sb->s_blocksize * 8) {
 619                 printk ("EXT2-fs: #inodes per group too big: %lu\n",
 620                         sb->u.ext2_sb.s_inodes_per_group);
 621                 goto failed_mount;
 622         }
 623
 624         if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
 625                 goto cantfind_ext2;
 626         sb->u.ext2_sb.s_groups_count = (le32_to_cpu(es->s_blocks_count) -
 627                                         le32_to_cpu(es->s_first_data_block) +
 628                                        EXT2_BLOCKS_PER_GROUP(sb) - 1) /
 629                                        EXT2_BLOCKS_PER_GROUP(sb);
 630         db_count = (sb->u.ext2_sb.s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
 631                    EXT2_DESC_PER_BLOCK(sb);
 632         sb->u.ext2_sb.s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
 633         if (sb->u.ext2_sb.s_group_desc == NULL) {
 634                 printk ("EXT2-fs: not enough memory\n");
 635                 goto failed_mount;
 636         }
 637         for (i = 0; i < db_count; i++) {
 638                 block = descriptor_loc(sb, logic_sb_block, i);
 639                 sbi->s_group_desc[i] = sb_bread(sb, block);
 640                 if (!sbi->s_group_desc[i]) {
 641                         for (j = 0; j < i; j++)
 642                                 brelse (sbi->s_group_desc[j]);
 643                         kfree(sbi->s_group_desc);
 644                         printk ("EXT2-fs: unable to read group descriptors\n");
 645                         goto failed_mount;
 646                 }
 647         }
 648         if (!ext2_check_descriptors (sb)) {
 649                 printk ("EXT2-fs: group descriptors corrupted!\n");
 650                 db_count = i;
 651                 goto failed_mount2;
 652         }
 653         for (i = 0; i < EXT2_MAX_GROUP_LOADED; i++) {
 654                 sb->u.ext2_sb.s_inode_bitmap_number[i] = 0;
 655                 sb->u.ext2_sb.s_inode_bitmap[i] = NULL;
 656                 sb->u.ext2_sb.s_block_bitmap_number[i] = 0;
 657                 sb->u.ext2_sb.s_block_bitmap[i] = NULL;
 658         }
 659         sb->u.ext2_sb.s_loaded_inode_bitmaps = 0;
 660         sb->u.ext2_sb.s_loaded_block_bitmaps = 0;
 661         sb->u.ext2_sb.s_gdb_count = db_count;
 662         /*
 663          * set up enough so that it can read an inode
 664          */
 665         sb->s_op = &ext2_sops;
 666         sb->s_root = d_alloc_root(iget(sb, EXT2_ROOT_INO));
 667         if (!sb->s_root || !S_ISDIR(sb->s_root->d_inode->i_mode) ||
 668             !sb->s_root->d_inode->i_blocks || !sb->s_root->d_inode->i_size) {
 669                 if (sb->s_root) {
 670                         dput(sb->s_root);
 671                         sb->s_root = NULL;
 672                         printk(KERN_ERR "EXT2-fs: corrupt root inode, run e2fsck\n");
 673                 } else
 674                         printk(KERN_ERR "EXT2-fs: get root inode failed\n");
 675                 goto failed_mount2;
 676         }
 677         ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
 678         return sb;
 679 cantfind_ext2:
 680         if (!silent)
 681                 printk ("VFS: Can't find ext2 filesystem on dev %s.\n",
 682                         bdevname(dev));
 683         goto failed_mount;
 684 failed_mount2:
 685         for (i = 0; i < db_count; i++)
 686                 brelse(sb->u.ext2_sb.s_group_desc[i]);
 687         kfree(sb->u.ext2_sb.s_group_desc);
 688 failed_mount:
 689         brelse(bh);
 690         return NULL;
 691 }
 692
 693 static void ext2_commit_super (struct super_block * sb,
 694                                struct ext2_super_block * es)
 695 {
 696         es->s_wtime = cpu_to_le32(CURRENT_TIME);
 697         mark_buffer_dirty(sb->u.ext2_sb.s_sbh);
 698         sb->s_dirt = 0;
 699 }
 700
 701 static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
 702 {
 703         es->s_wtime = cpu_to_le32(CURRENT_TIME);
 704         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 705         ll_rw_block(WRITE, 1, &EXT2_SB(sb)->s_sbh);
 706         wait_on_buffer(EXT2_SB(sb)->s_sbh);
 707         sb->s_dirt = 0;
 708 }
 709
 710 /*
 711  * In the second extended file system, it is not necessary to
 712  * write the super block since we use a mapping of the
 713  * disk super block in a buffer.
 714  *
 715  * However, this function is still used to set the fs valid
 716  * flags to 0.  We need to set this flag to 0 since the fs
 717  * may have been checked while mounted and e2fsck may have
 718  * set s_state to EXT2_VALID_FS after some corrections.
 719  */
 720
 721 void ext2_write_super (struct super_block * sb)
 722 {
 723         struct ext2_super_block * es;
 724
 725         if (!(sb->s_flags & MS_RDONLY)) {
 726                 es = sb->u.ext2_sb.s_es;
 727
 728                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
 729                         ext2_debug ("setting valid to 0\n");
 730                         es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) &
 731                                                   ~EXT2_VALID_FS);
 732                         es->s_mtime = cpu_to_le32(CURRENT_TIME);
 733                         ext2_sync_super(sb, es);
 734                 } else
 735                         ext2_commit_super (sb, es);
 736         }
 737         sb->s_dirt = 0;
 738 }
 739
 740 int ext2_remount (struct super_block * sb, int * flags, char * data)
 741 {
 742         struct ext2_super_block * es;
 743         unsigned short resuid = sb->u.ext2_sb.s_resuid;
 744         unsigned short resgid = sb->u.ext2_sb.s_resgid;
 745         unsigned long new_mount_opt;
 746         unsigned long tmp;
 747
 748         /*
 749          * Allow the "check" option to be passed as a remount option.
 750          */
 751         new_mount_opt = sb->u.ext2_sb.s_mount_opt;
 752         if (!parse_options (data, &tmp, &resuid, &resgid,
 753                             &new_mount_opt))
 754                 return -EINVAL;
 755
 756         sb->u.ext2_sb.s_mount_opt = new_mount_opt;
 757         sb->u.ext2_sb.s_resuid = resuid;
 758         sb->u.ext2_sb.s_resgid = resgid;
 759         es = sb->u.ext2_sb.s_es;
 760         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 761                 return 0;
 762         if (*flags & MS_RDONLY) {
 763                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
 764                     !(sb->u.ext2_sb.s_mount_state & EXT2_VALID_FS))
 765                         return 0;
 766                 /*
 767                  * OK, we are remounting a valid rw partition rdonly, so set
 768                  * the rdonly flag and then mark the partition as valid again.
 769                  */
 770                 es->s_state = cpu_to_le16(sb->u.ext2_sb.s_mount_state);
 771                 es->s_mtime = cpu_to_le32(CURRENT_TIME);
 772         } else {
 773                 int ret;
 774                 if ((ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
 775                                                ~EXT2_FEATURE_RO_COMPAT_SUPP))) {
 776                         printk("EXT2-fs: %s: couldn't remount RDWR because of "
 777                                "unsupported optional features (%x).\n",
 778                                bdevname(sb->s_dev), ret);
 779                         return -EROFS;
 780                 }
 781                 /*
 782                  * Mounting a RDONLY partition read-write, so reread and
 783                  * store the current valid flag.  (It may have been changed
 784                  * by e2fsck since we originally mounted the partition.)
 785                  */
 786                 sb->u.ext2_sb.s_mount_state = le16_to_cpu(es->s_state);
 787                 if (!ext2_setup_super (sb, es, 0))
 788                         sb->s_flags &= ~MS_RDONLY;
 789         }
 790         ext2_sync_super(sb, es);
 791         return 0;
 792 }
 793
 794 int ext2_statfs (struct super_block * sb, struct statfs * buf)
 795 {
 796         unsigned long overhead;
 797         int i;
 798
 799         if (test_opt (sb, MINIX_DF))
 800                 overhead = 0;
 801         else {
 802                 /*
 803                  * Compute the overhead (FS structures)
 804                  */
 805
 806                 /*
 807                  * All of the blocks before first_data_block are
 808                  * overhead
 809                  */
 810                 overhead = le32_to_cpu(sb->u.ext2_sb.s_es->s_first_data_block);
 811
 812                 /*
 813                  * Add the overhead attributed to the superblock and
 814                  * block group descriptors.  If the sparse superblocks
 815                  * feature is turned on, then not all groups have this.
 816                  */
 817                 for (i = 0; i < EXT2_SB(sb)->s_groups_count; i++)
 818                         overhead += ext2_bg_has_super(sb, i) +
 819                                 ext2_bg_num_gdb(sb, i);
 820
 821                 /*
 822                  * Every block group has an inode bitmap, a block
 823                  * bitmap, and an inode table.
 824                  */
 825                 overhead += (sb->u.ext2_sb.s_groups_count *
 826                              (2 + sb->u.ext2_sb.s_itb_per_group));
 827         }
 828
 829         buf->f_type = EXT2_SUPER_MAGIC;
 830         buf->f_bsize = sb->s_blocksize;
 831         buf->f_blocks = le32_to_cpu(sb->u.ext2_sb.s_es->s_blocks_count) - overhead;
 832         buf->f_bfree = ext2_count_free_blocks (sb);
 833         buf->f_bavail = buf->f_bfree - le32_to_cpu(sb->u.ext2_sb.s_es->s_r_blocks_count);
 834         if (buf->f_bfree < le32_to_cpu(sb->u.ext2_sb.s_es->s_r_blocks_count))
 835                 buf->f_bavail = 0;
 836         buf->f_files = le32_to_cpu(sb->u.ext2_sb.s_es->s_inodes_count);
 837         buf->f_ffree = ext2_count_free_inodes (sb);
 838         buf->f_namelen = EXT2_NAME_LEN;
 839         return 0;
 840 }
 841
 842 static DECLARE_FSTYPE_DEV(ext2_fs_type, "ext2", ext2_read_super);
 843
 844 static int __init init_ext2_fs(void)
 845 {
 846         return register_filesystem(&ext2_fs_type);
 847 }
 848
 849 static void __exit exit_ext2_fs(void)
 850 {
 851         unregister_filesystem(&ext2_fs_type);
 852 }
 853
 854 EXPORT_NO_SYMBOLS;
 855
 856 module_init(init_ext2_fs)
 857 module_exit(exit_ext2_fs)