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/slab.h>
  23 #include <linux/init.h>
  24 #include <linux/blkdev.h>
  25 #include <linux/parser.h>
  26 #include <linux/random.h>
  27 #include <linux/buffer_head.h>
  28 #include <linux/smp_lock.h>
  29 #include <linux/vfs.h>
  30 #include <asm/uaccess.h>
  31 #include "ext2.h"
  32 #include "xattr.h"
  33 #include "acl.h"
  34
  35 static void ext2_sync_super(struct super_block *sb,
  36                             struct ext2_super_block *es);
  37 static int ext2_remount (struct super_block * sb, int * flags, char * data);
  38 static int ext2_statfs (struct super_block * sb, struct kstatfs * buf);
  39
  40 void ext2_error (struct super_block * sb, const char * function,
  41                  const char * fmt, ...)
  42 {
  43         va_list args;
  44         struct ext2_sb_info *sbi = EXT2_SB(sb);
  45         struct ext2_super_block *es = sbi->s_es;
  46
  47         if (!(sb->s_flags & MS_RDONLY)) {
  48                 sbi->s_mount_state |= EXT2_ERROR_FS;
  49                 es->s_state =
  50                         cpu_to_le16(le16_to_cpu(es->s_state) | EXT2_ERROR_FS);
  51                 ext2_sync_super(sb, es);
  52         }
  53
  54         va_start(args, fmt);
  55         printk(KERN_CRIT "EXT2-fs error (device %s): %s: ",sb->s_id, function);
  56         vprintk(fmt, args);
  57         printk("\n");
  58         va_end(args);
  59
  60         if (test_opt(sb, ERRORS_PANIC))
  61                 panic("EXT2-fs panic from previous error\n");
  62         if (test_opt(sb, ERRORS_RO)) {
  63                 printk("Remounting filesystem read-only\n");
  64                 sb->s_flags |= MS_RDONLY;
  65         }
  66 }
  67
  68 void ext2_warning (struct super_block * sb, const char * function,
  69                    const char * fmt, ...)
  70 {
  71         va_list args;
  72
  73         va_start(args, fmt);
  74         printk(KERN_WARNING "EXT2-fs warning (device %s): %s: ",
  75                sb->s_id, function);
  76         vprintk(fmt, args);
  77         printk("\n");
  78         va_end(args);
  79 }
  80
  81 void ext2_update_dynamic_rev(struct super_block *sb)
  82 {
  83         struct ext2_super_block *es = EXT2_SB(sb)->s_es;
  84
  85         if (le32_to_cpu(es->s_rev_level) > EXT2_GOOD_OLD_REV)
  86                 return;
  87
  88         ext2_warning(sb, __FUNCTION__,
  89                      "updating to rev %d because of new feature flag, "
  90                      "running e2fsck is recommended",
  91                      EXT2_DYNAMIC_REV);
  92
  93         es->s_first_ino = cpu_to_le32(EXT2_GOOD_OLD_FIRST_INO);
  94         es->s_inode_size = cpu_to_le16(EXT2_GOOD_OLD_INODE_SIZE);
  95         es->s_rev_level = cpu_to_le32(EXT2_DYNAMIC_REV);
  96         /* leave es->s_feature_*compat flags alone */
  97         /* es->s_uuid will be set by e2fsck if empty */
  98
  99         /*
 100          * The rest of the superblock fields should be zero, and if not it
 101          * means they are likely already in use, so leave them alone.  We
 102          * can leave it up to e2fsck to clean up any inconsistencies there.
 103          */
 104 }
 105
 106 static void ext2_put_super (struct super_block * sb)
 107 {
 108         int db_count;
 109         int i;
 110         struct ext2_sb_info *sbi = EXT2_SB(sb);
 111
 112         ext2_xattr_put_super(sb);
 113         if (!(sb->s_flags & MS_RDONLY)) {
 114                 struct ext2_super_block *es = sbi->s_es;
 115
 116                 es->s_state = cpu_to_le16(sbi->s_mount_state);
 117                 ext2_sync_super(sb, es);
 118         }
 119         db_count = sbi->s_gdb_count;
 120         for (i = 0; i < db_count; i++)
 121                 if (sbi->s_group_desc[i])
 122                         brelse (sbi->s_group_desc[i]);
 123         kfree(sbi->s_group_desc);
 124         kfree(sbi->s_debts);
 125         percpu_counter_destroy(&sbi->s_freeblocks_counter);
 126         percpu_counter_destroy(&sbi->s_freeinodes_counter);
 127         percpu_counter_destroy(&sbi->s_dirs_counter);
 128         brelse (sbi->s_sbh);
 129         sb->s_fs_info = NULL;
 130         kfree(sbi);
 131
 132         return;
 133 }
 134
 135 static kmem_cache_t * ext2_inode_cachep;
 136
 137 static struct inode *ext2_alloc_inode(struct super_block *sb)
 138 {
 139         struct ext2_inode_info *ei;
 140         ei = (struct ext2_inode_info *)kmem_cache_alloc(ext2_inode_cachep, SLAB_KERNEL);
 141         if (!ei)
 142                 return NULL;
 143 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 144         ei->i_acl = EXT2_ACL_NOT_CACHED;
 145         ei->i_default_acl = EXT2_ACL_NOT_CACHED;
 146 #endif
 147         ei->vfs_inode.i_version = 1;
 148         return &ei->vfs_inode;
 149 }
 150
 151 static void ext2_destroy_inode(struct inode *inode)
 152 {
 153         kmem_cache_free(ext2_inode_cachep, EXT2_I(inode));
 154 }
 155
 156 static void init_once(void * foo, kmem_cache_t * cachep, unsigned long flags)
 157 {
 158         struct ext2_inode_info *ei = (struct ext2_inode_info *) foo;
 159
 160         if ((flags & (SLAB_CTOR_VERIFY|SLAB_CTOR_CONSTRUCTOR)) ==
 161             SLAB_CTOR_CONSTRUCTOR) {
 162                 rwlock_init(&ei->i_meta_lock);
 163 #ifdef CONFIG_EXT2_FS_XATTR
 164                 init_rwsem(&ei->xattr_sem);
 165 #endif
 166                 inode_init_once(&ei->vfs_inode);
 167         }
 168 }
 169
 170 static int init_inodecache(void)
 171 {
 172         ext2_inode_cachep = kmem_cache_create("ext2_inode_cache",
 173                                              sizeof(struct ext2_inode_info),
 174                                              0, SLAB_RECLAIM_ACCOUNT,
 175                                              init_once, NULL);
 176         if (ext2_inode_cachep == NULL)
 177                 return -ENOMEM;
 178         return 0;
 179 }
 180
 181 static void destroy_inodecache(void)
 182 {
 183         if (kmem_cache_destroy(ext2_inode_cachep))
 184                 printk(KERN_INFO "ext2_inode_cache: not all structures were freed\n");
 185 }
 186
 187 static void ext2_clear_inode(struct inode *inode)
 188 {
 189 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 190         struct ext2_inode_info *ei = EXT2_I(inode);
 191
 192         if (ei->i_acl && ei->i_acl != EXT2_ACL_NOT_CACHED) {
 193                 posix_acl_release(ei->i_acl);
 194                 ei->i_acl = EXT2_ACL_NOT_CACHED;
 195         }
 196         if (ei->i_default_acl && ei->i_default_acl != EXT2_ACL_NOT_CACHED) {
 197                 posix_acl_release(ei->i_default_acl);
 198                 ei->i_default_acl = EXT2_ACL_NOT_CACHED;
 199         }
 200 #endif
 201         if (!is_bad_inode(inode))
 202                 ext2_discard_prealloc(inode);
 203 }
 204
 205
 206 static struct super_operations ext2_sops = {
 207         .alloc_inode    = ext2_alloc_inode,
 208         .destroy_inode  = ext2_destroy_inode,
 209         .read_inode     = ext2_read_inode,
 210         .write_inode    = ext2_write_inode,
 211         .delete_inode   = ext2_delete_inode,
 212         .put_super      = ext2_put_super,
 213         .write_super    = ext2_write_super,
 214         .statfs         = ext2_statfs,
 215         .remount_fs     = ext2_remount,
 216         .clear_inode    = ext2_clear_inode,
 217 };
 218
 219 /* Yes, most of these are left as NULL!!
 220  * A NULL value implies the default, which works with ext2-like file
 221  * systems, but can be improved upon.
 222  * Currently only get_parent is required.
 223  */
 224 struct dentry *ext2_get_parent(struct dentry *child);
 225 static struct export_operations ext2_export_ops = {
 226         .get_parent = ext2_get_parent,
 227 };
 228
 229 static unsigned long get_sb_block(void **data)
 230 {
 231         unsigned long   sb_block;
 232         char            *options = (char *) *data;
 233
 234         if (!options || strncmp(options, "sb=", 3) != 0)
 235                 return 1;       /* Default location */
 236         options += 3;
 237         sb_block = simple_strtoul(options, &options, 0);
 238         if (*options && *options != ',') {
 239                 printk("EXT2-fs: Invalid sb specification: %s\n",
 240                        (char *) *data);
 241                 return 1;
 242         }
 243         if (*options == ',')
 244                 options++;
 245         *data = (void *) options;
 246         return sb_block;
 247 }
 248
 249 enum {
 250         Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid,
 251         Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic, Opt_err_ro,
 252         Opt_nouid32, Opt_check, Opt_nocheck, Opt_debug, Opt_oldalloc, Opt_orlov, Opt_nobh,
 253         Opt_user_xattr, Opt_nouser_xattr, Opt_acl, Opt_noacl, Opt_tagxid,
 254         Opt_ignore, Opt_err,
 255 };
 256
 257 static match_table_t tokens = {
 258         {Opt_bsd_df, "bsddf"},
 259         {Opt_minix_df, "minixdf"},
 260         {Opt_grpid, "grpid"},
 261         {Opt_grpid, "bsdgroups"},
 262         {Opt_nogrpid, "nogrpid"},
 263         {Opt_nogrpid, "sysvgroups"},
 264         {Opt_resgid, "resgid=%u"},
 265         {Opt_resuid, "resuid=%u"},
 266         {Opt_sb, "sb=%u"},
 267         {Opt_err_cont, "errors=continue"},
 268         {Opt_err_panic, "errors=panic"},
 269         {Opt_err_ro, "errors=remount-ro"},
 270         {Opt_nouid32, "nouid32"},
 271         {Opt_nocheck, "check=none"},
 272         {Opt_nocheck, "nocheck"},
 273         {Opt_check, "check"},
 274         {Opt_debug, "debug"},
 275         {Opt_oldalloc, "oldalloc"},
 276         {Opt_orlov, "orlov"},
 277         {Opt_nobh, "nobh"},
 278         {Opt_user_xattr, "user_xattr"},
 279         {Opt_nouser_xattr, "nouser_xattr"},
 280         {Opt_acl, "acl"},
 281         {Opt_noacl, "noacl"},
 282         {Opt_tagxid, "tagxid"},
 283         {Opt_ignore, "grpquota"},
 284         {Opt_ignore, "noquota"},
 285         {Opt_ignore, "quota"},
 286         {Opt_ignore, "usrquota"},
 287         {Opt_err, NULL}
 288 };
 289
 290 static int parse_options (char * options,
 291                           struct ext2_sb_info *sbi)
 292 {
 293         char * p;
 294         substring_t args[MAX_OPT_ARGS];
 295         unsigned long kind = EXT2_MOUNT_ERRORS_CONT;
 296         int option;
 297
 298         if (!options)
 299                 return 1;
 300
 301         while ((p = strsep (&options, ",")) != NULL) {
 302                 int token;
 303                 if (!*p)
 304                         continue;
 305
 306                 token = match_token(p, tokens, args);
 307                 switch (token) {
 308                 case Opt_bsd_df:
 309                         clear_opt (sbi->s_mount_opt, MINIX_DF);
 310                         break;
 311                 case Opt_minix_df:
 312                         set_opt (sbi->s_mount_opt, MINIX_DF);
 313                         break;
 314                 case Opt_grpid:
 315                         set_opt (sbi->s_mount_opt, GRPID);
 316                         break;
 317                 case Opt_nogrpid:
 318                         clear_opt (sbi->s_mount_opt, GRPID);
 319                         break;
 320                 case Opt_resuid:
 321                         if (match_int(&args[0], &option))
 322                                 return 0;
 323                         sbi->s_resuid = option;
 324                         break;
 325                 case Opt_resgid:
 326                         if (match_int(&args[0], &option))
 327                                 return 0;
 328                         sbi->s_resgid = option;
 329                         break;
 330                 case Opt_sb:
 331                         /* handled by get_sb_block() instead of here */
 332                         /* *sb_block = match_int(&args[0]); */
 333                         break;
 334                 case Opt_err_panic:
 335                         kind = EXT2_MOUNT_ERRORS_PANIC;
 336                         break;
 337                 case Opt_err_ro:
 338                         kind = EXT2_MOUNT_ERRORS_RO;
 339                         break;
 340                 case Opt_err_cont:
 341                         kind = EXT2_MOUNT_ERRORS_CONT;
 342                         break;
 343                 case Opt_nouid32:
 344                         set_opt (sbi->s_mount_opt, NO_UID32);
 345                         break;
 346 #ifndef CONFIG_INOXID_NONE
 347                 case Opt_tagxid:
 348                         set_opt (sbi->s_mount_opt, TAG_XID);
 349                         break;
 350 #endif
 351                 case Opt_check:
 352 #ifdef CONFIG_EXT2_CHECK
 353                         set_opt (sbi->s_mount_opt, CHECK);
 354 #else
 355                         printk("EXT2 Check option not supported\n");
 356 #endif
 357                         break;
 358                 case Opt_nocheck:
 359                         clear_opt (sbi->s_mount_opt, CHECK);
 360                         break;
 361                 case Opt_debug:
 362                         set_opt (sbi->s_mount_opt, DEBUG);
 363                         break;
 364                 case Opt_oldalloc:
 365                         set_opt (sbi->s_mount_opt, OLDALLOC);
 366                         break;
 367                 case Opt_orlov:
 368                         clear_opt (sbi->s_mount_opt, OLDALLOC);
 369                         break;
 370                 case Opt_nobh:
 371                         set_opt (sbi->s_mount_opt, NOBH);
 372                         break;
 373 #ifdef CONFIG_EXT2_FS_XATTR
 374                 case Opt_user_xattr:
 375                         set_opt (sbi->s_mount_opt, XATTR_USER);
 376                         break;
 377                 case Opt_nouser_xattr:
 378                         clear_opt (sbi->s_mount_opt, XATTR_USER);
 379                         break;
 380 #else
 381                 case Opt_user_xattr:
 382                 case Opt_nouser_xattr:
 383                         printk("EXT2 (no)user_xattr options not supported\n");
 384                         break;
 385 #endif
 386 #ifdef CONFIG_EXT2_FS_POSIX_ACL
 387                 case Opt_acl:
 388                         set_opt(sbi->s_mount_opt, POSIX_ACL);
 389                         break;
 390                 case Opt_noacl:
 391                         clear_opt(sbi->s_mount_opt, POSIX_ACL);
 392                         break;
 393 #else
 394                 case Opt_acl:
 395                 case Opt_noacl:
 396                         printk("EXT2 (no)acl options not supported\n");
 397                         break;
 398 #endif
 399                 case Opt_ignore:
 400                         break;
 401                 default:
 402                         return 0;
 403                 }
 404         }
 405         sbi->s_mount_opt |= kind;
 406         return 1;
 407 }
 408
 409 static int ext2_setup_super (struct super_block * sb,
 410                               struct ext2_super_block * es,
 411                               int read_only)
 412 {
 413         int res = 0;
 414         struct ext2_sb_info *sbi = EXT2_SB(sb);
 415
 416         if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
 417                 printk ("EXT2-fs warning: revision level too high, "
 418                         "forcing read-only mode\n");
 419                 res = MS_RDONLY;
 420         }
 421         if (read_only)
 422                 return res;
 423         if (!(sbi->s_mount_state & EXT2_VALID_FS))
 424                 printk ("EXT2-fs warning: mounting unchecked fs, "
 425                         "running e2fsck is recommended\n");
 426         else if ((sbi->s_mount_state & EXT2_ERROR_FS))
 427                 printk ("EXT2-fs warning: mounting fs with errors, "
 428                         "running e2fsck is recommended\n");
 429         else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
 430                  le16_to_cpu(es->s_mnt_count) >=
 431                  (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
 432                 printk ("EXT2-fs warning: maximal mount count reached, "
 433                         "running e2fsck is recommended\n");
 434         else if (le32_to_cpu(es->s_checkinterval) &&
 435                 (le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= get_seconds()))
 436                 printk ("EXT2-fs warning: checktime reached, "
 437                         "running e2fsck is recommended\n");
 438         if (!le16_to_cpu(es->s_max_mnt_count))
 439                 es->s_max_mnt_count = cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
 440         es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
 441         ext2_write_super(sb);
 442         if (test_opt (sb, DEBUG))
 443                 printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
 444                         "bpg=%lu, ipg=%lu, mo=%04lx]\n",
 445                         EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
 446                         sbi->s_frag_size,
 447                         sbi->s_groups_count,
 448                         EXT2_BLOCKS_PER_GROUP(sb),
 449                         EXT2_INODES_PER_GROUP(sb),
 450                         sbi->s_mount_opt);
 451 #ifdef CONFIG_EXT2_CHECK
 452         if (test_opt (sb, CHECK)) {
 453                 ext2_check_blocks_bitmap (sb);
 454                 ext2_check_inodes_bitmap (sb);
 455         }
 456 #endif
 457         return res;
 458 }
 459
 460 static int ext2_check_descriptors (struct super_block * sb)
 461 {
 462         int i;
 463         int desc_block = 0;
 464         struct ext2_sb_info *sbi = EXT2_SB(sb);
 465         unsigned long block = le32_to_cpu(sbi->s_es->s_first_data_block);
 466         struct ext2_group_desc * gdp = NULL;
 467
 468         ext2_debug ("Checking group descriptors");
 469
 470         for (i = 0; i < sbi->s_groups_count; i++)
 471         {
 472                 if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
 473                         gdp = (struct ext2_group_desc *) sbi->s_group_desc[desc_block++]->b_data;
 474                 if (le32_to_cpu(gdp->bg_block_bitmap) < block ||
 475                     le32_to_cpu(gdp->bg_block_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
 476                 {
 477                         ext2_error (sb, "ext2_check_descriptors",
 478                                     "Block bitmap for group %d"
 479                                     " not in group (block %lu)!",
 480                                     i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
 481                         return 0;
 482                 }
 483                 if (le32_to_cpu(gdp->bg_inode_bitmap) < block ||
 484                     le32_to_cpu(gdp->bg_inode_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
 485                 {
 486                         ext2_error (sb, "ext2_check_descriptors",
 487                                     "Inode bitmap for group %d"
 488                                     " not in group (block %lu)!",
 489                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_bitmap));
 490                         return 0;
 491                 }
 492                 if (le32_to_cpu(gdp->bg_inode_table) < block ||
 493                     le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group >=
 494                     block + EXT2_BLOCKS_PER_GROUP(sb))
 495                 {
 496                         ext2_error (sb, "ext2_check_descriptors",
 497                                     "Inode table for group %d"
 498                                     " not in group (block %lu)!",
 499                                     i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
 500                         return 0;
 501                 }
 502                 block += EXT2_BLOCKS_PER_GROUP(sb);
 503                 gdp++;
 504         }
 505         return 1;
 506 }
 507
 508 #define log2(n) ffz(~(n))
 509
 510 /*
 511  * Maximal file size.  There is a direct, and {,double-,triple-}indirect
 512  * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
 513  * We need to be 1 filesystem block less than the 2^32 sector limit.
 514  */
 515 static loff_t ext2_max_size(int bits)
 516 {
 517         loff_t res = EXT2_NDIR_BLOCKS;
 518         res += 1LL << (bits-2);
 519         res += 1LL << (2*(bits-2));
 520         res += 1LL << (3*(bits-2));
 521         res <<= bits;
 522         if (res > (512LL << 32) - (1 << bits))
 523                 res = (512LL << 32) - (1 << bits);
 524         return res;
 525 }
 526
 527 static unsigned long descriptor_loc(struct super_block *sb,
 528                                     unsigned long logic_sb_block,
 529                                     int nr)
 530 {
 531         struct ext2_sb_info *sbi = EXT2_SB(sb);
 532         unsigned long bg, first_data_block, first_meta_bg;
 533         int has_super = 0;
 534
 535         first_data_block = le32_to_cpu(sbi->s_es->s_first_data_block);
 536         first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);
 537
 538         if (!EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_META_BG) ||
 539             nr < first_meta_bg)
 540                 return (logic_sb_block + nr + 1);
 541         bg = sbi->s_desc_per_block * nr;
 542         if (ext2_bg_has_super(sb, bg))
 543                 has_super = 1;
 544         return (first_data_block + has_super + (bg * sbi->s_blocks_per_group));
 545 }
 546
 547 static int ext2_fill_super(struct super_block *sb, void *data, int silent)
 548 {
 549         struct buffer_head * bh;
 550         struct ext2_sb_info * sbi;
 551         struct ext2_super_block * es;
 552         struct inode *root;
 553         unsigned long block;
 554         unsigned long sb_block = get_sb_block(&data);
 555         unsigned long logic_sb_block;
 556         unsigned long offset = 0;
 557         unsigned long def_mount_opts;
 558         int blocksize = BLOCK_SIZE;
 559         int db_count;
 560         int i, j;
 561         __le32 features;
 562
 563         sbi = kmalloc(sizeof(*sbi), GFP_KERNEL);
 564         if (!sbi)
 565                 return -ENOMEM;
 566         sb->s_fs_info = sbi;
 567         memset(sbi, 0, sizeof(*sbi));
 568
 569         /*
 570          * See what the current blocksize for the device is, and
 571          * use that as the blocksize.  Otherwise (or if the blocksize
 572          * is smaller than the default) use the default.
 573          * This is important for devices that have a hardware
 574          * sectorsize that is larger than the default.
 575          */
 576         blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
 577         if (!blocksize) {
 578                 printk ("EXT2-fs: unable to set blocksize\n");
 579                 goto failed_sbi;
 580         }
 581
 582         /*
 583          * If the superblock doesn't start on a hardware sector boundary,
 584          * calculate the offset.
 585          */
 586         if (blocksize != BLOCK_SIZE) {
 587                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 588                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 589         } else {
 590                 logic_sb_block = sb_block;
 591         }
 592
 593         if (!(bh = sb_bread(sb, logic_sb_block))) {
 594                 printk ("EXT2-fs: unable to read superblock\n");
 595                 goto failed_sbi;
 596         }
 597         /*
 598          * Note: s_es must be initialized as soon as possible because
 599          *       some ext2 macro-instructions depend on its value
 600          */
 601         es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 602         sbi->s_es = es;
 603         sb->s_magic = le16_to_cpu(es->s_magic);
 604         sb->s_flags |= MS_ONE_SECOND;
 605
 606         if (sb->s_magic != EXT2_SUPER_MAGIC)
 607                 goto cantfind_ext2;
 608
 609         /* Set defaults before we parse the mount options */
 610         def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
 611         if (def_mount_opts & EXT2_DEFM_DEBUG)
 612                 set_opt(sbi->s_mount_opt, DEBUG);
 613         if (def_mount_opts & EXT2_DEFM_BSDGROUPS)
 614                 set_opt(sbi->s_mount_opt, GRPID);
 615         if (def_mount_opts & EXT2_DEFM_UID16)
 616                 set_opt(sbi->s_mount_opt, NO_UID32);
 617         if (def_mount_opts & EXT2_DEFM_XATTR_USER)
 618                 set_opt(sbi->s_mount_opt, XATTR_USER);
 619         if (def_mount_opts & EXT2_DEFM_ACL)
 620                 set_opt(sbi->s_mount_opt, POSIX_ACL);
 621
 622         if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_PANIC)
 623                 set_opt(sbi->s_mount_opt, ERRORS_PANIC);
 624         else if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_RO)
 625                 set_opt(sbi->s_mount_opt, ERRORS_RO);
 626
 627         sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
 628         sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
 629
 630         if (!parse_options ((char *) data, sbi))
 631                 goto failed_mount;
 632
 633         if (EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_TAG_XID)
 634                 sb->s_flags |= MS_TAGXID;
 635         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
 636                 ((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
 637                  MS_POSIXACL : 0);
 638
 639         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
 640             (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
 641              EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
 642              EXT2_HAS_INCOMPAT_FEATURE(sb, ~0U)))
 643                 printk("EXT2-fs warning: feature flags set on rev 0 fs, "
 644                        "running e2fsck is recommended\n");
 645         /*
 646          * Check feature flags regardless of the revision level, since we
 647          * previously didn't change the revision level when setting the flags,
 648          * so there is a chance incompat flags are set on a rev 0 filesystem.
 649          */
 650         features = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP);
 651         if (features) {
 652                 printk("EXT2-fs: %s: couldn't mount because of "
 653                        "unsupported optional features (%x).\n",
 654                        sb->s_id, le32_to_cpu(features));
 655                 goto failed_mount;
 656         }
 657         if (!(sb->s_flags & MS_RDONLY) &&
 658             (features = EXT2_HAS_RO_COMPAT_FEATURE(sb, ~EXT2_FEATURE_RO_COMPAT_SUPP))){
 659                 printk("EXT2-fs: %s: couldn't mount RDWR because of "
 660                        "unsupported optional features (%x).\n",
 661                        sb->s_id, le32_to_cpu(features));
 662                 goto failed_mount;
 663         }
 664
 665         blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);
 666
 667         /* If the blocksize doesn't match, re-read the thing.. */
 668         if (sb->s_blocksize != blocksize) {
 669                 brelse(bh);
 670
 671                 if (!sb_set_blocksize(sb, blocksize)) {
 672                         printk(KERN_ERR "EXT2-fs: blocksize too small for device.\n");
 673                         goto failed_sbi;
 674                 }
 675
 676                 logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
 677                 offset = (sb_block*BLOCK_SIZE) % blocksize;
 678                 bh = sb_bread(sb, logic_sb_block);
 679                 if(!bh) {
 680                         printk("EXT2-fs: Couldn't read superblock on "
 681                                "2nd try.\n");
 682                         goto failed_sbi;
 683                 }
 684                 es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 685                 sbi->s_es = es;
 686                 if (es->s_magic != cpu_to_le16(EXT2_SUPER_MAGIC)) {
 687                         printk ("EXT2-fs: Magic mismatch, very weird !\n");
 688                         goto failed_mount;
 689                 }
 690         }
 691
 692         sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);
 693
 694         if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
 695                 sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
 696                 sbi->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
 697         } else {
 698                 sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
 699                 sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
 700                 if ((sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
 701                     (sbi->s_inode_size & (sbi->s_inode_size - 1)) ||
 702                     (sbi->s_inode_size > blocksize)) {
 703                         printk ("EXT2-fs: unsupported inode size: %d\n",
 704                                 sbi->s_inode_size);
 705                         goto failed_mount;
 706                 }
 707         }
 708
 709         sbi->s_frag_size = EXT2_MIN_FRAG_SIZE <<
 710                                    le32_to_cpu(es->s_log_frag_size);
 711         if (sbi->s_frag_size == 0)
 712                 goto cantfind_ext2;
 713         sbi->s_frags_per_block = sb->s_blocksize / sbi->s_frag_size;
 714
 715         sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
 716         sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
 717         sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
 718
 719         if (EXT2_INODE_SIZE(sb) == 0)
 720                 goto cantfind_ext2;
 721         sbi->s_inodes_per_block = sb->s_blocksize / EXT2_INODE_SIZE(sb);
 722         if (sbi->s_inodes_per_block == 0)
 723                 goto cantfind_ext2;
 724         sbi->s_itb_per_group = sbi->s_inodes_per_group /
 725                                         sbi->s_inodes_per_block;
 726         sbi->s_desc_per_block = sb->s_blocksize /
 727                                         sizeof (struct ext2_group_desc);
 728         sbi->s_sbh = bh;
 729         sbi->s_mount_state = le16_to_cpu(es->s_state);
 730         sbi->s_addr_per_block_bits =
 731                 log2 (EXT2_ADDR_PER_BLOCK(sb));
 732         sbi->s_desc_per_block_bits =
 733                 log2 (EXT2_DESC_PER_BLOCK(sb));
 734
 735         if (sb->s_magic != EXT2_SUPER_MAGIC)
 736                 goto cantfind_ext2;
 737
 738         if (sb->s_blocksize != bh->b_size) {
 739                 if (!silent)
 740                         printk ("VFS: Unsupported blocksize on dev "
 741                                 "%s.\n", sb->s_id);
 742                 goto failed_mount;
 743         }
 744
 745         if (sb->s_blocksize != sbi->s_frag_size) {
 746                 printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
 747                         sbi->s_frag_size, sb->s_blocksize);
 748                 goto failed_mount;
 749         }
 750
 751         if (sbi->s_blocks_per_group > sb->s_blocksize * 8) {
 752                 printk ("EXT2-fs: #blocks per group too big: %lu\n",
 753                         sbi->s_blocks_per_group);
 754                 goto failed_mount;
 755         }
 756         if (sbi->s_frags_per_group > sb->s_blocksize * 8) {
 757                 printk ("EXT2-fs: #fragments per group too big: %lu\n",
 758                         sbi->s_frags_per_group);
 759                 goto failed_mount;
 760         }
 761         if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
 762                 printk ("EXT2-fs: #inodes per group too big: %lu\n",
 763                         sbi->s_inodes_per_group);
 764                 goto failed_mount;
 765         }
 766
 767         if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
 768                 goto cantfind_ext2;
 769         sbi->s_groups_count = (le32_to_cpu(es->s_blocks_count) -
 770                                         le32_to_cpu(es->s_first_data_block) +
 771                                        EXT2_BLOCKS_PER_GROUP(sb) - 1) /
 772                                        EXT2_BLOCKS_PER_GROUP(sb);
 773         db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
 774                    EXT2_DESC_PER_BLOCK(sb);
 775         sbi->s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
 776         if (sbi->s_group_desc == NULL) {
 777                 printk ("EXT2-fs: not enough memory\n");
 778                 goto failed_mount;
 779         }
 780         percpu_counter_init(&sbi->s_freeblocks_counter);
 781         percpu_counter_init(&sbi->s_freeinodes_counter);
 782         percpu_counter_init(&sbi->s_dirs_counter);
 783         bgl_lock_init(&sbi->s_blockgroup_lock);
 784         sbi->s_debts = kmalloc(sbi->s_groups_count * sizeof(*sbi->s_debts),
 785                                GFP_KERNEL);
 786         if (!sbi->s_debts) {
 787                 printk ("EXT2-fs: not enough memory\n");
 788                 goto failed_mount_group_desc;
 789         }
 790         memset(sbi->s_debts, 0, sbi->s_groups_count * sizeof(*sbi->s_debts));
 791         for (i = 0; i < db_count; i++) {
 792                 block = descriptor_loc(sb, logic_sb_block, i);
 793                 sbi->s_group_desc[i] = sb_bread(sb, block);
 794                 if (!sbi->s_group_desc[i]) {
 795                         for (j = 0; j < i; j++)
 796                                 brelse (sbi->s_group_desc[j]);
 797                         printk ("EXT2-fs: unable to read group descriptors\n");
 798                         goto failed_mount_group_desc;
 799                 }
 800         }
 801         if (!ext2_check_descriptors (sb)) {
 802                 printk ("EXT2-fs: group descriptors corrupted!\n");
 803                 db_count = i;
 804                 goto failed_mount2;
 805         }
 806         sbi->s_gdb_count = db_count;
 807         get_random_bytes(&sbi->s_next_generation, sizeof(u32));
 808         spin_lock_init(&sbi->s_next_gen_lock);
 809         /*
 810          * set up enough so that it can read an inode
 811          */
 812         sb->s_op = &ext2_sops;
 813         sb->s_export_op = &ext2_export_ops;
 814         sb->s_xattr = ext2_xattr_handlers;
 815         root = iget(sb, EXT2_ROOT_INO);
 816         sb->s_root = d_alloc_root(root);
 817         if (!sb->s_root) {
 818                 iput(root);
 819                 printk(KERN_ERR "EXT2-fs: get root inode failed\n");
 820                 goto failed_mount2;
 821         }
 822         if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
 823                 dput(sb->s_root);
 824                 sb->s_root = NULL;
 825                 printk(KERN_ERR "EXT2-fs: corrupt root inode, run e2fsck\n");
 826                 goto failed_mount2;
 827         }
 828         if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
 829                 ext2_warning(sb, __FUNCTION__,
 830                         "mounting ext3 filesystem as ext2\n");
 831         ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
 832         percpu_counter_mod(&sbi->s_freeblocks_counter,
 833                                 ext2_count_free_blocks(sb));
 834         percpu_counter_mod(&sbi->s_freeinodes_counter,
 835                                 ext2_count_free_inodes(sb));
 836         percpu_counter_mod(&sbi->s_dirs_counter,
 837                                 ext2_count_dirs(sb));
 838         return 0;
 839
 840 cantfind_ext2:
 841         if (!silent)
 842                 printk("VFS: Can't find an ext2 filesystem on dev %s.\n",
 843                        sb->s_id);
 844         goto failed_mount;
 845
 846 failed_mount2:
 847         for (i = 0; i < db_count; i++)
 848                 brelse(sbi->s_group_desc[i]);
 849 failed_mount_group_desc:
 850         kfree(sbi->s_group_desc);
 851         kfree(sbi->s_debts);
 852 failed_mount:
 853         brelse(bh);
 854 failed_sbi:
 855         sb->s_fs_info = NULL;
 856         kfree(sbi);
 857         return -EINVAL;
 858 }
 859
 860 static void ext2_commit_super (struct super_block * sb,
 861                                struct ext2_super_block * es)
 862 {
 863         es->s_wtime = cpu_to_le32(get_seconds());
 864         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 865         sb->s_dirt = 0;
 866 }
 867
 868 static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
 869 {
 870         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
 871         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
 872         es->s_wtime = cpu_to_le32(get_seconds());
 873         mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
 874         sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
 875         sb->s_dirt = 0;
 876 }
 877
 878 /*
 879  * In the second extended file system, it is not necessary to
 880  * write the super block since we use a mapping of the
 881  * disk super block in a buffer.
 882  *
 883  * However, this function is still used to set the fs valid
 884  * flags to 0.  We need to set this flag to 0 since the fs
 885  * may have been checked while mounted and e2fsck may have
 886  * set s_state to EXT2_VALID_FS after some corrections.
 887  */
 888
 889 void ext2_write_super (struct super_block * sb)
 890 {
 891         struct ext2_super_block * es;
 892         lock_kernel();
 893         if (!(sb->s_flags & MS_RDONLY)) {
 894                 es = EXT2_SB(sb)->s_es;
 895
 896                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
 897                         ext2_debug ("setting valid to 0\n");
 898                         es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) &
 899                                                   ~EXT2_VALID_FS);
 900                         es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
 901                         es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
 902                         es->s_mtime = cpu_to_le32(get_seconds());
 903                         ext2_sync_super(sb, es);
 904                 } else
 905                         ext2_commit_super (sb, es);
 906         }
 907         sb->s_dirt = 0;
 908         unlock_kernel();
 909 }
 910
 911 static int ext2_remount (struct super_block * sb, int * flags, char * data)
 912 {
 913         struct ext2_sb_info * sbi = EXT2_SB(sb);
 914         struct ext2_super_block * es;
 915
 916         /*
 917          * Allow the "check" option to be passed as a remount option.
 918          */
 919         if (!parse_options (data, sbi))
 920                 return -EINVAL;
 921
 922         sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
 923                 ((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);
 924
 925         es = sbi->s_es;
 926         if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
 927                 return 0;
 928         if (*flags & MS_RDONLY) {
 929                 if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
 930                     !(sbi->s_mount_state & EXT2_VALID_FS))
 931                         return 0;
 932                 /*
 933                  * OK, we are remounting a valid rw partition rdonly, so set
 934                  * the rdonly flag and then mark the partition as valid again.
 935                  */
 936                 es->s_state = cpu_to_le16(sbi->s_mount_state);
 937                 es->s_mtime = cpu_to_le32(get_seconds());
 938         } else {
 939                 __le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
 940                                                ~EXT2_FEATURE_RO_COMPAT_SUPP);
 941                 if (ret) {
 942                         printk("EXT2-fs: %s: couldn't remount RDWR because of "
 943                                "unsupported optional features (%x).\n",
 944                                sb->s_id, le32_to_cpu(ret));
 945                         return -EROFS;
 946                 }
 947                 /*
 948                  * Mounting a RDONLY partition read-write, so reread and
 949                  * store the current valid flag.  (It may have been changed
 950                  * by e2fsck since we originally mounted the partition.)
 951                  */
 952                 sbi->s_mount_state = le16_to_cpu(es->s_state);
 953                 if (!ext2_setup_super (sb, es, 0))
 954                         sb->s_flags &= ~MS_RDONLY;
 955         }
 956         ext2_sync_super(sb, es);
 957         return 0;
 958 }
 959
 960 static int ext2_statfs (struct super_block * sb, struct kstatfs * buf)
 961 {
 962         struct ext2_sb_info *sbi = EXT2_SB(sb);
 963         unsigned long overhead;
 964         int i;
 965
 966         if (test_opt (sb, MINIX_DF))
 967                 overhead = 0;
 968         else {
 969                 /*
 970                  * Compute the overhead (FS structures)
 971                  */
 972
 973                 /*
 974                  * All of the blocks before first_data_block are
 975                  * overhead
 976                  */
 977                 overhead = le32_to_cpu(sbi->s_es->s_first_data_block);
 978
 979                 /*
 980                  * Add the overhead attributed to the superblock and
 981                  * block group descriptors.  If the sparse superblocks
 982                  * feature is turned on, then not all groups have this.
 983                  */
 984                 for (i = 0; i < sbi->s_groups_count; i++)
 985                         overhead += ext2_bg_has_super(sb, i) +
 986                                 ext2_bg_num_gdb(sb, i);
 987
 988                 /*
 989                  * Every block group has an inode bitmap, a block
 990                  * bitmap, and an inode table.
 991                  */
 992                 overhead += (sbi->s_groups_count *
 993                              (2 + sbi->s_itb_per_group));
 994         }
 995
 996         buf->f_type = EXT2_SUPER_MAGIC;
 997         buf->f_bsize = sb->s_blocksize;
 998         buf->f_blocks = le32_to_cpu(sbi->s_es->s_blocks_count) - overhead;
 999         buf->f_bfree = ext2_count_free_blocks(sb);
1000         buf->f_bavail = buf->f_bfree - le32_to_cpu(sbi->s_es->s_r_blocks_count);
1001         if (buf->f_bfree < le32_to_cpu(sbi->s_es->s_r_blocks_count))
1002                 buf->f_bavail = 0;
1003         buf->f_files = le32_to_cpu(sbi->s_es->s_inodes_count);
1004         buf->f_ffree = ext2_count_free_inodes (sb);
1005         buf->f_namelen = EXT2_NAME_LEN;
1006         return 0;
1007 }
1008
1009 static struct super_block *ext2_get_sb(struct file_system_type *fs_type,
1010         int flags, const char *dev_name, void *data)
1011 {
1012         return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super);
1013 }
1014
1015 static struct file_system_type ext2_fs_type = {
1016         .owner          = THIS_MODULE,
1017         .name           = "ext2",
1018         .get_sb         = ext2_get_sb,
1019         .kill_sb        = kill_block_super,
1020         .fs_flags       = FS_REQUIRES_DEV,
1021 };
1022
1023 static int __init init_ext2_fs(void)
1024 {
1025         int err = init_ext2_xattr();
1026         if (err)
1027                 return err;
1028         err = init_inodecache();
1029         if (err)
1030                 goto out1;
1031         err = register_filesystem(&ext2_fs_type);
1032         if (err)
1033                 goto out;
1034         return 0;
1035 out:
1036         destroy_inodecache();
1037 out1:
1038         exit_ext2_xattr();
1039         return err;
1040 }
1041
1042 static void __exit exit_ext2_fs(void)
1043 {
1044         unregister_filesystem(&ext2_fs_type);
1045         destroy_inodecache();
1046         exit_ext2_xattr();
1047 }
1048
1049 module_init(init_ext2_fs)
1050 module_exit(exit_ext2_fs)