root/fs/ext2/super.c

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DEFINITIONS

This source file includes following definitions.
  1. ext2_error
  2. ext2_panic
  3. ext2_warning
  4. ext2_put_super
  5. parse_options
  6. ext2_setup_super
  7. ext2_check_descriptors
  8. ext2_read_super
  9. ext2_commit_super
  10. ext2_write_super
  11. ext2_remount
  12. init_module
  13. cleanup_module
  14. ext2_statfs

   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 
  16 #ifdef MODULE
  17 #include <linux/module.h>
  18 #include <linux/version.h>
  19 #else
  20 #define MOD_INC_USE_COUNT
  21 #define MOD_DEC_USE_COUNT
  22 #endif
  23 
  24 #include <stdarg.h>
  25 
  26 #include <asm/bitops.h>
  27 #include <asm/segment.h>
  28 #include <asm/system.h>
  29 
  30 #include <linux/errno.h>
  31 #include <linux/fs.h>
  32 #include <linux/ext2_fs.h>
  33 #include <linux/malloc.h>
  34 #include <linux/sched.h>
  35 #include <linux/stat.h>
  36 #include <linux/string.h>
  37 #include <linux/locks.h>
  38 
  39 static char error_buf[1024];
  40 
  41 void ext2_error (struct super_block * sb, const char * function,
     /* [previous][next][first][last][top][bottom][index][help] */
  42                  const char * fmt, ...)
  43 {
  44         va_list args;
  45 
  46         if (!(sb->s_flags & MS_RDONLY)) {
  47                 sb->u.ext2_sb.s_mount_state |= EXT2_ERROR_FS;
  48                 sb->u.ext2_sb.s_es->s_state |= EXT2_ERROR_FS;
  49                 mark_buffer_dirty(sb->u.ext2_sb.s_sbh, 1);
  50                 sb->s_dirt = 1;
  51         }
  52         va_start (args, fmt);
  53         vsprintf (error_buf, fmt, args);
  54         va_end (args);
  55         if (test_opt (sb, ERRORS_PANIC) ||
  56             (sb->u.ext2_sb.s_es->s_errors == EXT2_ERRORS_PANIC &&
  57              !test_opt (sb, ERRORS_CONT) && !test_opt (sb, ERRORS_RO)))
  58                 panic ("EXT2-fs panic (device %s): %s: %s\n",
  59                        kdevname(sb->s_dev), function, error_buf);
  60         printk (KERN_CRIT "EXT2-fs error (device %s): %s: %s\n",
  61                 kdevname(sb->s_dev), function, error_buf);
  62         if (test_opt (sb, ERRORS_RO) ||
  63             (sb->u.ext2_sb.s_es->s_errors == EXT2_ERRORS_RO &&
  64              !test_opt (sb, ERRORS_CONT) && !test_opt (sb, ERRORS_PANIC))) {
  65                 printk ("Remounting filesystem read-only\n");
  66                 sb->s_flags |= MS_RDONLY;
  67         }
  68 }
  69 
  70 NORET_TYPE void ext2_panic (struct super_block * sb, const char * function,
     /* [previous][next][first][last][top][bottom][index][help] */
  71                             const char * fmt, ...)
  72 {
  73         va_list args;
  74 
  75         if (!(sb->s_flags & MS_RDONLY)) {
  76                 sb->u.ext2_sb.s_mount_state |= EXT2_ERROR_FS;
  77                 sb->u.ext2_sb.s_es->s_state |= EXT2_ERROR_FS;
  78                 mark_buffer_dirty(sb->u.ext2_sb.s_sbh, 1);
  79                 sb->s_dirt = 1;
  80         }
  81         va_start (args, fmt);
  82         vsprintf (error_buf, fmt, args);
  83         va_end (args);
  84         panic ("EXT2-fs panic (device %s): %s: %s\n",
  85                kdevname(sb->s_dev), function, error_buf);
  86 }
  87 
  88 void ext2_warning (struct super_block * sb, const char * function,
     /* [previous][next][first][last][top][bottom][index][help] */
  89                    const char * fmt, ...)
  90 {
  91         va_list args;
  92 
  93         va_start (args, fmt);
  94         vsprintf (error_buf, fmt, args);
  95         va_end (args);
  96         printk (KERN_WARNING "EXT2-fs warning (device %s): %s: %s\n",
  97                 kdevname(sb->s_dev), function, error_buf);
  98 }
  99 
 100 void ext2_put_super (struct super_block * sb)
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 101 {
 102         int db_count;
 103         int i;
 104 
 105         lock_super (sb);
 106         if (!(sb->s_flags & MS_RDONLY)) {
 107                 sb->u.ext2_sb.s_es->s_state = sb->u.ext2_sb.s_mount_state;
 108                 mark_buffer_dirty(sb->u.ext2_sb.s_sbh, 1);
 109         }
 110         sb->s_dev = 0;
 111         db_count = sb->u.ext2_sb.s_db_per_group;
 112         for (i = 0; i < db_count; i++)
 113                 if (sb->u.ext2_sb.s_group_desc[i])
 114                         brelse (sb->u.ext2_sb.s_group_desc[i]);
 115         kfree_s (sb->u.ext2_sb.s_group_desc,
 116                  db_count * sizeof (struct buffer_head *));
 117         for (i = 0; i < EXT2_MAX_GROUP_LOADED; i++)
 118                 if (sb->u.ext2_sb.s_inode_bitmap[i])
 119                         brelse (sb->u.ext2_sb.s_inode_bitmap[i]);
 120         for (i = 0; i < EXT2_MAX_GROUP_LOADED; i++)
 121                 if (sb->u.ext2_sb.s_block_bitmap[i])
 122                         brelse (sb->u.ext2_sb.s_block_bitmap[i]);
 123         brelse (sb->u.ext2_sb.s_sbh);
 124         unlock_super (sb);
 125         MOD_DEC_USE_COUNT;
 126         return;
 127 }
 128 
 129 static struct super_operations ext2_sops = { 
 130         ext2_read_inode,
 131         NULL,
 132         ext2_write_inode,
 133         ext2_put_inode,
 134         ext2_put_super,
 135         ext2_write_super,
 136         ext2_statfs,
 137         ext2_remount
 138 };
 139 
 140 /*
 141  * This function has been shamelessly adapted from the msdos fs
 142  */
 143 static int parse_options (char * options, unsigned long * sb_block,
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 144                           unsigned short *resuid, unsigned short * resgid,
 145                           unsigned long * mount_options)
 146 {
 147         char * this_char;
 148         char * value;
 149 
 150         if (!options)
 151                 return 1;
 152         for (this_char = strtok (options, ",");
 153              this_char != NULL;
 154              this_char = strtok (NULL, ",")) {
 155                 if ((value = strchr (this_char, '=')) != NULL)
 156                         *value++ = 0;
 157                 if (!strcmp (this_char, "bsddf"))
 158                         clear_opt (*mount_options, MINIX_DF);
 159                 else if (!strcmp (this_char, "check")) {
 160                         if (!value || !*value)
 161                                 set_opt (*mount_options, CHECK_NORMAL);
 162                         else if (!strcmp (value, "none")) {
 163                                 clear_opt (*mount_options, CHECK_NORMAL);
 164                                 clear_opt (*mount_options, CHECK_STRICT);
 165                         }
 166                         else if (strcmp (value, "normal"))
 167                                 set_opt (*mount_options, CHECK_NORMAL);
 168                         else if (strcmp (value, "strict")) {
 169                                 set_opt (*mount_options, CHECK_NORMAL);
 170                                 set_opt (*mount_options, CHECK_STRICT);
 171                         }
 172                         else {
 173                                 printk ("EXT2-fs: Invalid check option: %s\n",
 174                                         value);
 175                                 return 0;
 176                         }
 177                 }
 178                 else if (!strcmp (this_char, "debug"))
 179                         set_opt (*mount_options, DEBUG);
 180                 else if (!strcmp (this_char, "errors")) {
 181                         if (!value || !*value) {
 182                                 printk ("EXT2-fs: the errors option requires "
 183                                         "an argument");
 184                                 return 0;
 185                         }
 186                         if (!strcmp (value, "continue")) {
 187                                 clear_opt (*mount_options, ERRORS_RO);
 188                                 clear_opt (*mount_options, ERRORS_PANIC);
 189                                 set_opt (*mount_options, ERRORS_CONT);
 190                         }
 191                         else if (!strcmp (value, "remount-ro")) {
 192                                 clear_opt (*mount_options, ERRORS_CONT);
 193                                 clear_opt (*mount_options, ERRORS_PANIC);
 194                                 set_opt (*mount_options, ERRORS_RO);
 195                         }
 196                         else if (!strcmp (value, "panic")) {
 197                                 clear_opt (*mount_options, ERRORS_CONT);
 198                                 clear_opt (*mount_options, ERRORS_RO);
 199                                 set_opt (*mount_options, ERRORS_PANIC);
 200                         }
 201                         else {
 202                                 printk ("EXT2-fs: Invalid errors option: %s\n",
 203                                         value);
 204                                 return 0;
 205                         }
 206                 }
 207                 else if (!strcmp (this_char, "grpid") ||
 208                          !strcmp (this_char, "bsdgroups"))
 209                         set_opt (*mount_options, GRPID);
 210                 else if (!strcmp (this_char, "minixdf"))
 211                         set_opt (*mount_options, MINIX_DF);
 212                 else if (!strcmp (this_char, "nocheck")) {
 213                         clear_opt (*mount_options, CHECK_NORMAL);
 214                         clear_opt (*mount_options, CHECK_STRICT);
 215                 }
 216                 else if (!strcmp (this_char, "nogrpid") ||
 217                          !strcmp (this_char, "sysvgroups"))
 218                         clear_opt (*mount_options, GRPID);
 219                 else if (!strcmp (this_char, "resgid")) {
 220                         if (!value || !*value) {
 221                                 printk ("EXT2-fs: the resgid option requires "
 222                                         "an argument");
 223                                 return 0;
 224                         }
 225                         *resgid = simple_strtoul (value, &value, 0);
 226                         if (*value) {
 227                                 printk ("EXT2-fs: Invalid resgid option: %s\n",
 228                                         value);
 229                                 return 0;
 230                         }
 231                 }
 232                 else if (!strcmp (this_char, "resuid")) {
 233                         if (!value || !*value) {
 234                                 printk ("EXT2-fs: the resuid option requires "
 235                                         "an argument");
 236                                 return 0;
 237                         }
 238                         *resuid = simple_strtoul (value, &value, 0);
 239                         if (*value) {
 240                                 printk ("EXT2-fs: Invalid resuid option: %s\n",
 241                                         value);
 242                                 return 0;
 243                         }
 244                 }
 245                 else if (!strcmp (this_char, "sb")) {
 246                         if (!value || !*value) {
 247                                 printk ("EXT2-fs: the sb option requires "
 248                                         "an argument");
 249                                 return 0;
 250                         }
 251                         *sb_block = simple_strtoul (value, &value, 0);
 252                         if (*value) {
 253                                 printk ("EXT2-fs: Invalid sb option: %s\n",
 254                                         value);
 255                                 return 0;
 256                         }
 257                 }
 258                 else {
 259                         printk ("EXT2-fs: Unrecognized mount option %s\n", this_char);
 260                         return 0;
 261                 }
 262         }
 263         return 1;
 264 }
 265 
 266 static void ext2_setup_super (struct super_block * sb,
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 267                               struct ext2_super_block * es)
 268 {
 269         if (es->s_rev_level > EXT2_CURRENT_REV) {
 270                         printk ("EXT2-fs warning: revision level too high, "
 271                                 "forcing read/only mode\n");
 272                         sb->s_flags |= MS_RDONLY;
 273         }
 274         if (!(sb->s_flags & MS_RDONLY)) {
 275                 if (!(sb->u.ext2_sb.s_mount_state & EXT2_VALID_FS))
 276                         printk ("EXT2-fs warning: mounting unchecked fs, "
 277                                 "running e2fsck is recommended\n");
 278                 else if ((sb->u.ext2_sb.s_mount_state & EXT2_ERROR_FS))
 279                         printk ("EXT2-fs warning: mounting fs with errors, "
 280                                 "running e2fsck is recommended\n");
 281                 else if (es->s_max_mnt_count >= 0 &&
 282                          es->s_mnt_count >= (unsigned short) es->s_max_mnt_count)
 283                         printk ("EXT2-fs warning: maximal mount count reached, "
 284                                 "running e2fsck is recommended\n");
 285                 else if (es->s_checkinterval &&
 286                         (es->s_lastcheck + es->s_checkinterval <= CURRENT_TIME))
 287                         printk ("EXT2-fs warning: checktime reached, "
 288                                 "running e2fsck is recommended\n");
 289                 es->s_state &= ~EXT2_VALID_FS;
 290                 if (!es->s_max_mnt_count)
 291                         es->s_max_mnt_count = EXT2_DFL_MAX_MNT_COUNT;
 292                 es->s_mnt_count++;
 293                 es->s_mtime = CURRENT_TIME;
 294                 mark_buffer_dirty(sb->u.ext2_sb.s_sbh, 1);
 295                 sb->s_dirt = 1;
 296                 if (test_opt (sb, DEBUG))
 297                         printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
 298                                 "bpg=%lu, ipg=%lu, mo=%04lx]\n",
 299                                 EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
 300                                 sb->u.ext2_sb.s_frag_size,
 301                                 sb->u.ext2_sb.s_groups_count,
 302                                 EXT2_BLOCKS_PER_GROUP(sb),
 303                                 EXT2_INODES_PER_GROUP(sb),
 304                                 sb->u.ext2_sb.s_mount_opt);
 305                 if (test_opt (sb, CHECK)) {
 306                         ext2_check_blocks_bitmap (sb);
 307                         ext2_check_inodes_bitmap (sb);
 308                 }
 309         }
 310 }
 311 
 312 static int ext2_check_descriptors (struct super_block * sb)
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 313 {
 314         int i;
 315         int desc_block = 0;
 316         unsigned long block = sb->u.ext2_sb.s_es->s_first_data_block;
 317         struct ext2_group_desc * gdp = NULL;
 318 
 319         ext2_debug ("Checking group descriptors");
 320 
 321         for (i = 0; i < sb->u.ext2_sb.s_groups_count; i++)
 322         {
 323                 if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
 324                         gdp = (struct ext2_group_desc *) sb->u.ext2_sb.s_group_desc[desc_block++]->b_data;
 325                 if (gdp->bg_block_bitmap < block ||
 326                     gdp->bg_block_bitmap >= block + EXT2_BLOCKS_PER_GROUP(sb))
 327                 {
 328                         ext2_error (sb, "ext2_check_descriptors",
 329                                     "Block bitmap for group %d"
 330                                     " not in group (block %lu)!",
 331                                     i, (unsigned long) gdp->bg_block_bitmap);
 332                         return 0;
 333                 }
 334                 if (gdp->bg_inode_bitmap < block ||
 335                     gdp->bg_inode_bitmap >= block + EXT2_BLOCKS_PER_GROUP(sb))
 336                 {
 337                         ext2_error (sb, "ext2_check_descriptors",
 338                                     "Inode bitmap for group %d"
 339                                     " not in group (block %lu)!",
 340                                     i, (unsigned long) gdp->bg_inode_bitmap);
 341                         return 0;
 342                 }
 343                 if (gdp->bg_inode_table < block ||
 344                     gdp->bg_inode_table + sb->u.ext2_sb.s_itb_per_group >=
 345                     block + EXT2_BLOCKS_PER_GROUP(sb))
 346                 {
 347                         ext2_error (sb, "ext2_check_descriptors",
 348                                     "Inode table for group %d"
 349                                     " not in group (block %lu)!",
 350                                     i, (unsigned long) gdp->bg_inode_table);
 351                         return 0;
 352                 }
 353                 block += EXT2_BLOCKS_PER_GROUP(sb);
 354                 gdp++;
 355         }
 356         return 1;
 357 }
 358 
 359 #define log2(n) ffz(~(n))
 360 
 361 struct super_block * ext2_read_super (struct super_block * sb, void * data,
     /* [previous][next][first][last][top][bottom][index][help] */
 362                                       int silent)
 363 {
 364         struct buffer_head * bh;
 365         struct ext2_super_block * es;
 366         unsigned long sb_block = 1;
 367         unsigned short resuid = EXT2_DEF_RESUID;
 368         unsigned short resgid = EXT2_DEF_RESGID;
 369         unsigned long logic_sb_block = 1;
 370         kdev_t dev = sb->s_dev;
 371         int db_count;
 372         int i, j;
 373 
 374         set_opt (sb->u.ext2_sb.s_mount_opt, CHECK_NORMAL);
 375         if (!parse_options ((char *) data, &sb_block, &resuid, &resgid,
 376             &sb->u.ext2_sb.s_mount_opt)) {
 377                 sb->s_dev = 0;
 378                 return NULL;
 379         }
 380 
 381         MOD_INC_USE_COUNT;
 382         lock_super (sb);
 383         set_blocksize (dev, BLOCK_SIZE);
 384         if (!(bh = bread (dev, sb_block, BLOCK_SIZE))) {
 385                 sb->s_dev = 0;
 386                 unlock_super (sb);
 387                 printk ("EXT2-fs: unable to read superblock\n");
 388                 MOD_DEC_USE_COUNT;
 389                 return NULL;
 390         }
 391         /*
 392          * Note: s_es must be initialized s_es as soon as possible because
 393          * some ext2 macro-instructions depend on its value
 394          */
 395         es = (struct ext2_super_block *) bh->b_data;
 396         sb->u.ext2_sb.s_es = es;
 397         sb->s_magic = es->s_magic;
 398         if (sb->s_magic != EXT2_SUPER_MAGIC) {
 399                 sb->s_dev = 0;
 400                 unlock_super (sb);
 401                 brelse (bh);
 402                 if (!silent)
 403                         printk ("VFS: Can't find an ext2 filesystem on dev "
 404                                 "%s.\n", kdevname(dev));
 405                 return NULL;
 406         }
 407         sb->s_blocksize_bits = sb->u.ext2_sb.s_es->s_log_block_size + 10;
 408         sb->s_blocksize = 1 << sb->s_blocksize_bits;
 409         if (sb->s_blocksize != BLOCK_SIZE && 
 410             (sb->s_blocksize == 1024 || sb->s_blocksize == 2048 ||  
 411              sb->s_blocksize == 4096)) {
 412                 unsigned long offset;
 413 
 414                 brelse (bh);
 415                 set_blocksize (dev, sb->s_blocksize);
 416                 logic_sb_block = (sb_block*BLOCK_SIZE) / sb->s_blocksize;
 417                 offset = (sb_block*BLOCK_SIZE) % sb->s_blocksize;
 418                 bh = bread (dev, logic_sb_block, sb->s_blocksize);
 419                 if(!bh) {
 420                         MOD_DEC_USE_COUNT;
 421                         return NULL;
 422                       }
 423                 es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 424                 sb->u.ext2_sb.s_es = es;
 425                 if (es->s_magic != EXT2_SUPER_MAGIC) {
 426                         sb->s_dev = 0;
 427                         unlock_super (sb);
 428                         brelse (bh);
 429                         printk ("EXT2-fs: Magic mismatch, very weird !\n");
 430                         MOD_DEC_USE_COUNT;
 431                         return NULL;
 432                 }
 433         }
 434         sb->u.ext2_sb.s_frag_size = EXT2_MIN_FRAG_SIZE <<
 435                                    es->s_log_frag_size;
 436         if (sb->u.ext2_sb.s_frag_size)
 437                 sb->u.ext2_sb.s_frags_per_block = sb->s_blocksize /
 438                                                   sb->u.ext2_sb.s_frag_size;
 439         else
 440                 sb->s_magic = 0;
 441         sb->u.ext2_sb.s_blocks_per_group = es->s_blocks_per_group;
 442         sb->u.ext2_sb.s_frags_per_group = es->s_frags_per_group;
 443         sb->u.ext2_sb.s_inodes_per_group = es->s_inodes_per_group;
 444         sb->u.ext2_sb.s_inodes_per_block = sb->s_blocksize /
 445                                            sizeof (struct ext2_inode);
 446         sb->u.ext2_sb.s_itb_per_group = sb->u.ext2_sb.s_inodes_per_group /
 447                                         sb->u.ext2_sb.s_inodes_per_block;
 448         sb->u.ext2_sb.s_desc_per_block = sb->s_blocksize /
 449                                          sizeof (struct ext2_group_desc);
 450         sb->u.ext2_sb.s_sbh = bh;
 451         if (resuid != EXT2_DEF_RESUID)
 452                 sb->u.ext2_sb.s_resuid = resuid;
 453         else
 454                 sb->u.ext2_sb.s_resuid = es->s_def_resuid;
 455         if (resgid != EXT2_DEF_RESGID)
 456                 sb->u.ext2_sb.s_resgid = resgid;
 457         else
 458                 sb->u.ext2_sb.s_resgid = es->s_def_resgid;
 459         sb->u.ext2_sb.s_mount_state = es->s_state;
 460         sb->u.ext2_sb.s_rename_lock = 0;
 461         sb->u.ext2_sb.s_rename_wait = NULL;
 462         sb->u.ext2_sb.s_addr_per_block_bits =
 463                 log2 (EXT2_ADDR_PER_BLOCK(sb));
 464         sb->u.ext2_sb.s_inodes_per_block_bits =
 465                 log2 (EXT2_INODES_PER_BLOCK(sb));
 466         sb->u.ext2_sb.s_desc_per_block_bits =
 467                 log2 (EXT2_DESC_PER_BLOCK(sb));
 468         if (sb->s_magic != EXT2_SUPER_MAGIC) {
 469                 sb->s_dev = 0;
 470                 unlock_super (sb);
 471                 brelse (bh);
 472                 if (!silent)
 473                         printk ("VFS: Can't find an ext2 filesystem on dev "
 474                                 "%s.\n",
 475                                 kdevname(dev));
 476                 MOD_DEC_USE_COUNT;
 477                 return NULL;
 478         }
 479         if (sb->s_blocksize != bh->b_size) {
 480                 sb->s_dev = 0;
 481                 unlock_super (sb);
 482                 brelse (bh);
 483                 if (!silent)
 484                         printk ("VFS: Unsupported blocksize on dev "
 485                                 "%s.\n", kdevname(dev));
 486                 MOD_DEC_USE_COUNT;
 487                 return NULL;
 488         }
 489 
 490         if (sb->s_blocksize != sb->u.ext2_sb.s_frag_size) {
 491                 sb->s_dev = 0;
 492                 unlock_super (sb);
 493                 brelse (bh);
 494                 printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
 495                         sb->u.ext2_sb.s_frag_size, sb->s_blocksize);
 496                 MOD_DEC_USE_COUNT;
 497                 return NULL;
 498         }
 499 
 500         if (sb->u.ext2_sb.s_blocks_per_group > sb->s_blocksize * 8) {
 501                 sb->s_dev = 0;
 502                 unlock_super (sb);
 503                 brelse (bh);
 504                 printk ("EXT2-fs: #blocks per group too big: %lu\n",
 505                         sb->u.ext2_sb.s_blocks_per_group);
 506                 MOD_DEC_USE_COUNT;
 507                 return NULL;
 508         }
 509         if (sb->u.ext2_sb.s_frags_per_group > sb->s_blocksize * 8) {
 510                 sb->s_dev = 0;
 511                 unlock_super (sb);
 512                 brelse (bh);
 513                 printk ("EXT2-fs: #fragments per group too big: %lu\n",
 514                         sb->u.ext2_sb.s_frags_per_group);
 515                 MOD_DEC_USE_COUNT;
 516                 return NULL;
 517         }
 518         if (sb->u.ext2_sb.s_inodes_per_group > sb->s_blocksize * 8) {
 519                 sb->s_dev = 0;
 520                 unlock_super (sb);
 521                 brelse (bh);
 522                 printk ("EXT2-fs: #inodes per group too big: %lu\n",
 523                         sb->u.ext2_sb.s_inodes_per_group);
 524                 MOD_DEC_USE_COUNT;
 525                 return NULL;
 526         }
 527 
 528         sb->u.ext2_sb.s_groups_count = (es->s_blocks_count -
 529                                         es->s_first_data_block +
 530                                        EXT2_BLOCKS_PER_GROUP(sb) - 1) /
 531                                        EXT2_BLOCKS_PER_GROUP(sb);
 532         db_count = (sb->u.ext2_sb.s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
 533                    EXT2_DESC_PER_BLOCK(sb);
 534         sb->u.ext2_sb.s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
 535         if (sb->u.ext2_sb.s_group_desc == NULL) {
 536                 sb->s_dev = 0;
 537                 unlock_super (sb);
 538                 brelse (bh);
 539                 printk ("EXT2-fs: not enough memory\n");
 540                 MOD_DEC_USE_COUNT;
 541                 return NULL;
 542         }
 543         for (i = 0; i < db_count; i++) {
 544                 sb->u.ext2_sb.s_group_desc[i] = bread (dev, logic_sb_block + i + 1,
 545                                                        sb->s_blocksize);
 546                 if (!sb->u.ext2_sb.s_group_desc[i]) {
 547                         sb->s_dev = 0;
 548                         unlock_super (sb);
 549                         for (j = 0; j < i; j++)
 550                                 brelse (sb->u.ext2_sb.s_group_desc[j]);
 551                         kfree_s (sb->u.ext2_sb.s_group_desc,
 552                                  db_count * sizeof (struct buffer_head *));
 553                         brelse (bh);
 554                         printk ("EXT2-fs: unable to read group descriptors\n");
 555                         MOD_DEC_USE_COUNT;
 556                         return NULL;
 557                 }
 558         }
 559         if (!ext2_check_descriptors (sb)) {
 560                 sb->s_dev = 0;
 561                 unlock_super (sb);
 562                 for (j = 0; j < db_count; j++)
 563                         brelse (sb->u.ext2_sb.s_group_desc[j]);
 564                 kfree_s (sb->u.ext2_sb.s_group_desc,
 565                          db_count * sizeof (struct buffer_head *));
 566                 brelse (bh);
 567                 printk ("EXT2-fs: group descriptors corrupted !\n");
 568                 MOD_DEC_USE_COUNT;
 569                 return NULL;
 570         }
 571         for (i = 0; i < EXT2_MAX_GROUP_LOADED; i++) {
 572                 sb->u.ext2_sb.s_inode_bitmap_number[i] = 0;
 573                 sb->u.ext2_sb.s_inode_bitmap[i] = NULL;
 574                 sb->u.ext2_sb.s_block_bitmap_number[i] = 0;
 575                 sb->u.ext2_sb.s_block_bitmap[i] = NULL;
 576         }
 577         sb->u.ext2_sb.s_loaded_inode_bitmaps = 0;
 578         sb->u.ext2_sb.s_loaded_block_bitmaps = 0;
 579         sb->u.ext2_sb.s_db_per_group = db_count;
 580         unlock_super (sb);
 581         /*
 582          * set up enough so that it can read an inode
 583          */
 584         sb->s_dev = dev;
 585         sb->s_op = &ext2_sops;
 586         if (!(sb->s_mounted = iget (sb, EXT2_ROOT_INO))) {
 587                 sb->s_dev = 0;
 588                 for (i = 0; i < db_count; i++)
 589                         if (sb->u.ext2_sb.s_group_desc[i])
 590                                 brelse (sb->u.ext2_sb.s_group_desc[i]);
 591                 kfree_s (sb->u.ext2_sb.s_group_desc,
 592                          db_count * sizeof (struct buffer_head *));
 593                 brelse (bh);
 594                 printk ("EXT2-fs: get root inode failed\n");
 595                 MOD_DEC_USE_COUNT;
 596                 return NULL;
 597         }
 598         ext2_setup_super (sb, es);
 599         return sb;
 600 }
 601 
 602 static void ext2_commit_super (struct super_block * sb,
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 603                                struct ext2_super_block * es)
 604 {
 605         es->s_wtime = CURRENT_TIME;
 606         mark_buffer_dirty(sb->u.ext2_sb.s_sbh, 1);
 607         sb->s_dirt = 0;
 608 }
 609 
 610 /*
 611  * In the second extended file system, it is not necessary to
 612  * write the super block since we use a mapping of the
 613  * disk super block in a buffer.
 614  *
 615  * However, this function is still used to set the fs valid
 616  * flags to 0.  We need to set this flag to 0 since the fs
 617  * may have been checked while mounted and e2fsck may have
 618  * set s_state to EXT2_VALID_FS after some corrections.
 619  */
 620 
 621 void ext2_write_super (struct super_block * sb)
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 622 {
 623         struct ext2_super_block * es;
 624 
 625         if (!(sb->s_flags & MS_RDONLY)) {
 626                 es = sb->u.ext2_sb.s_es;
 627 
 628                 ext2_debug ("setting valid to 0\n");
 629 
 630                 if (es->s_state & EXT2_VALID_FS) {
 631                         es->s_state &= ~EXT2_VALID_FS;
 632                         es->s_mtime = CURRENT_TIME;
 633                 }
 634                 ext2_commit_super (sb, es);
 635         }
 636         sb->s_dirt = 0;
 637 }
 638 
 639 int ext2_remount (struct super_block * sb, int * flags, char * data)
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 640 {
 641         struct ext2_super_block * es;
 642         unsigned short resuid = sb->u.ext2_sb.s_resuid;
 643         unsigned short resgid = sb->u.ext2_sb.s_resgid;
 644         unsigned long new_mount_opt;
 645         unsigned long tmp;
 646 
 647         /*
 648          * Allow the "check" option to be passed as a remount option.
 649          */
 650         set_opt (new_mount_opt, CHECK_NORMAL);
 651         if (!parse_options (data, &tmp, &resuid, &resgid,
 652                             &new_mount_opt))
 653                 return -EINVAL;
 654 
 655         sb->u.ext2_sb.s_mount_opt = new_mount_opt;
 656         sb->u.ext2_sb.s_resuid = resuid;
 657         sb->u.ext2_sb.s_resgid = resgid;
 658         es = sb->u.ext2_sb.s_es;
 659         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 660                 return 0;
 661         if (*flags & MS_RDONLY) {
 662                 if (es->s_state & EXT2_VALID_FS ||
 663                     !(sb->u.ext2_sb.s_mount_state & EXT2_VALID_FS))
 664                         return 0;
 665                 /*
 666                  * OK, we are remounting a valid rw partition rdonly, so set
 667                  * the rdonly flag and then mark the partition as valid again.
 668                  */
 669                 es->s_state = sb->u.ext2_sb.s_mount_state;
 670                 es->s_mtime = CURRENT_TIME;
 671                 mark_buffer_dirty(sb->u.ext2_sb.s_sbh, 1);
 672                 sb->s_dirt = 1;
 673                 ext2_commit_super (sb, es);
 674         }
 675         else {
 676                 /*
 677                  * Mounting a RDONLY partition read-write, so reread and
 678                  * store the current valid flag.  (It may have been changed 
 679                  * by e2fsck since we originally mounted the partition.)
 680                  */
 681                 sb->u.ext2_sb.s_mount_state = es->s_state;
 682                 sb->s_flags &= ~MS_RDONLY;
 683                 ext2_setup_super (sb, es);
 684         }
 685         return 0;
 686 }
 687 
 688 #ifdef MODULE
 689 
 690 char kernel_version[] = UTS_RELEASE;
 691 
 692 static struct file_system_type ext2_fs_type = {
 693         ext2_read_super, "ext2", 1, NULL
 694 };
 695 
 696 int init_module(void)
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 697 {
 698         register_filesystem(&ext2_fs_type);
 699         return 0;
 700 }
 701 
 702 void cleanup_module(void)
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 703 {
 704         unregister_filesystem(&ext2_fs_type);
 705 }
 706 
 707 #endif
 708 
 709 void ext2_statfs (struct super_block * sb, struct statfs * buf, int bufsiz)
     /* [previous][next][first][last][top][bottom][index][help] */
 710 {
 711         unsigned long overhead;
 712         unsigned long overhead_per_group;
 713         struct statfs tmp;
 714 
 715         if (test_opt (sb, MINIX_DF))
 716                 overhead = 0;
 717         else {
 718                 /*
 719                  * Compute the overhead (FS structures)
 720                  */
 721                 overhead_per_group = 1 /* super block */ +
 722                                      sb->u.ext2_sb.s_db_per_group /* descriptors */ +
 723                                      1 /* block bitmap */ +
 724                                      1 /* inode bitmap */ +
 725                                      sb->u.ext2_sb.s_itb_per_group /* inode table */;
 726                 overhead = sb->u.ext2_sb.s_es->s_first_data_block +
 727                            sb->u.ext2_sb.s_groups_count * overhead_per_group;
 728         }
 729 
 730         tmp.f_type = EXT2_SUPER_MAGIC;
 731         tmp.f_bsize = sb->s_blocksize;
 732         tmp.f_blocks = sb->u.ext2_sb.s_es->s_blocks_count - overhead;
 733         tmp.f_bfree = ext2_count_free_blocks (sb);
 734         tmp.f_bavail = tmp.f_bfree - sb->u.ext2_sb.s_es->s_r_blocks_count;
 735         if (tmp.f_bfree < sb->u.ext2_sb.s_es->s_r_blocks_count)
 736                 tmp.f_bavail = 0;
 737         tmp.f_files = sb->u.ext2_sb.s_es->s_inodes_count;
 738         tmp.f_ffree = ext2_count_free_inodes (sb);
 739         tmp.f_namelen = EXT2_NAME_LEN;
 740         memcpy_tofs(buf, &tmp, bufsiz);
 741 }

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