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super.c

/*
 *  linux/fs/ext2/super.c
 *
 * Copyright (C) 1992, 1993, 1994, 1995
 * Remy Card (card@masi.ibp.fr)
 * Laboratoire MASI - Institut Blaise Pascal
 * Universite Pierre et Marie Curie (Paris VI)
 *
 *  from
 *
 *  linux/fs/minix/inode.c
 *
 *  Copyright (C) 1991, 1992  Linus Torvalds
 *
 *  Big-endian to little-endian byte-swapping/bitmaps by
 *        David S. Miller (davem@caip.rutgers.edu), 1995
 */

#include <linux/module.h>
#include <linux/string.h>
#include <linux/fs.h>
#include <linux/slab.h>
#include <linux/init.h>
#include <linux/blkdev.h>
#include <linux/parser.h>
#include <linux/random.h>
#include <linux/buffer_head.h>
#include <linux/exportfs.h>
#include <linux/smp_lock.h>
#include <linux/vfs.h>
#include <linux/seq_file.h>
#include <linux/mount.h>
#include <linux/log2.h>
#include <asm/uaccess.h>
#include "ext2.h"
#include "xattr.h"
#include "acl.h"
#include "xip.h"

static void ext2_sync_super(struct super_block *sb,
                      struct ext2_super_block *es);
static int ext2_remount (struct super_block * sb, int * flags, char * data);
static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf);

void ext2_error (struct super_block * sb, const char * function,
             const char * fmt, ...)
{
      va_list args;
      struct ext2_sb_info *sbi = EXT2_SB(sb);
      struct ext2_super_block *es = sbi->s_es;

      if (!(sb->s_flags & MS_RDONLY)) {
            sbi->s_mount_state |= EXT2_ERROR_FS;
            es->s_state =
                  cpu_to_le16(le16_to_cpu(es->s_state) | EXT2_ERROR_FS);
            ext2_sync_super(sb, es);
      }

      va_start(args, fmt);
      printk(KERN_CRIT "EXT2-fs error (device %s): %s: ",sb->s_id, function);
      vprintk(fmt, args);
      printk("\n");
      va_end(args);

      if (test_opt(sb, ERRORS_PANIC))
            panic("EXT2-fs panic from previous error\n");
      if (test_opt(sb, ERRORS_RO)) {
            printk("Remounting filesystem read-only\n");
            sb->s_flags |= MS_RDONLY;
      }
}

void ext2_warning (struct super_block * sb, const char * function,
               const char * fmt, ...)
{
      va_list args;

      va_start(args, fmt);
      printk(KERN_WARNING "EXT2-fs warning (device %s): %s: ",
             sb->s_id, function);
      vprintk(fmt, args);
      printk("\n");
      va_end(args);
}

void ext2_update_dynamic_rev(struct super_block *sb)
{
      struct ext2_super_block *es = EXT2_SB(sb)->s_es;

      if (le32_to_cpu(es->s_rev_level) > EXT2_GOOD_OLD_REV)
            return;

      ext2_warning(sb, __FUNCTION__,
                 "updating to rev %d because of new feature flag, "
                 "running e2fsck is recommended",
                 EXT2_DYNAMIC_REV);

      es->s_first_ino = cpu_to_le32(EXT2_GOOD_OLD_FIRST_INO);
      es->s_inode_size = cpu_to_le16(EXT2_GOOD_OLD_INODE_SIZE);
      es->s_rev_level = cpu_to_le32(EXT2_DYNAMIC_REV);
      /* leave es->s_feature_*compat flags alone */
      /* es->s_uuid will be set by e2fsck if empty */

      /*
       * The rest of the superblock fields should be zero, and if not it
       * means they are likely already in use, so leave them alone.  We
       * can leave it up to e2fsck to clean up any inconsistencies there.
       */
}

static void ext2_put_super (struct super_block * sb)
{
      int db_count;
      int i;
      struct ext2_sb_info *sbi = EXT2_SB(sb);

      ext2_xattr_put_super(sb);
      if (!(sb->s_flags & MS_RDONLY)) {
            struct ext2_super_block *es = sbi->s_es;

            es->s_state = cpu_to_le16(sbi->s_mount_state);
            ext2_sync_super(sb, es);
      }
      db_count = sbi->s_gdb_count;
      for (i = 0; i < db_count; i++)
            if (sbi->s_group_desc[i])
                  brelse (sbi->s_group_desc[i]);
      kfree(sbi->s_group_desc);
      kfree(sbi->s_debts);
      percpu_counter_destroy(&sbi->s_freeblocks_counter);
      percpu_counter_destroy(&sbi->s_freeinodes_counter);
      percpu_counter_destroy(&sbi->s_dirs_counter);
      brelse (sbi->s_sbh);
      sb->s_fs_info = NULL;
      kfree(sbi);

      return;
}

static struct kmem_cache * ext2_inode_cachep;

static struct inode *ext2_alloc_inode(struct super_block *sb)
{
      struct ext2_inode_info *ei;
      ei = (struct ext2_inode_info *)kmem_cache_alloc(ext2_inode_cachep, GFP_KERNEL);
      if (!ei)
            return NULL;
#ifdef CONFIG_EXT2_FS_POSIX_ACL
      ei->i_acl = EXT2_ACL_NOT_CACHED;
      ei->i_default_acl = EXT2_ACL_NOT_CACHED;
#endif
      ei->i_block_alloc_info = NULL;
      ei->vfs_inode.i_version = 1;
      return &ei->vfs_inode;
}

static void ext2_destroy_inode(struct inode *inode)
{
      kmem_cache_free(ext2_inode_cachep, EXT2_I(inode));
}

static void init_once(struct kmem_cache * cachep, void *foo)
{
      struct ext2_inode_info *ei = (struct ext2_inode_info *) foo;

      rwlock_init(&ei->i_meta_lock);
#ifdef CONFIG_EXT2_FS_XATTR
      init_rwsem(&ei->xattr_sem);
#endif
      mutex_init(&ei->truncate_mutex);
      inode_init_once(&ei->vfs_inode);
}

static int init_inodecache(void)
{
      ext2_inode_cachep = kmem_cache_create("ext2_inode_cache",
                                   sizeof(struct ext2_inode_info),
                                   0, (SLAB_RECLAIM_ACCOUNT|
                                    SLAB_MEM_SPREAD),
                                   init_once);
      if (ext2_inode_cachep == NULL)
            return -ENOMEM;
      return 0;
}

static void destroy_inodecache(void)
{
      kmem_cache_destroy(ext2_inode_cachep);
}

static void ext2_clear_inode(struct inode *inode)
{
      struct ext2_block_alloc_info *rsv = EXT2_I(inode)->i_block_alloc_info;
#ifdef CONFIG_EXT2_FS_POSIX_ACL
      struct ext2_inode_info *ei = EXT2_I(inode);

      if (ei->i_acl && ei->i_acl != EXT2_ACL_NOT_CACHED) {
            posix_acl_release(ei->i_acl);
            ei->i_acl = EXT2_ACL_NOT_CACHED;
      }
      if (ei->i_default_acl && ei->i_default_acl != EXT2_ACL_NOT_CACHED) {
            posix_acl_release(ei->i_default_acl);
            ei->i_default_acl = EXT2_ACL_NOT_CACHED;
      }
#endif
      ext2_discard_reservation(inode);
      EXT2_I(inode)->i_block_alloc_info = NULL;
      if (unlikely(rsv))
            kfree(rsv);
}

static int ext2_show_options(struct seq_file *seq, struct vfsmount *vfs)
{
      struct super_block *sb = vfs->mnt_sb;
      struct ext2_sb_info *sbi = EXT2_SB(sb);
      struct ext2_super_block *es = sbi->s_es;
      unsigned long def_mount_opts;

      def_mount_opts = le32_to_cpu(es->s_default_mount_opts);

      if (sbi->s_sb_block != 1)
            seq_printf(seq, ",sb=%lu", sbi->s_sb_block);
      if (test_opt(sb, MINIX_DF))
            seq_puts(seq, ",minixdf");
      if (test_opt(sb, GRPID))
            seq_puts(seq, ",grpid");
      if (!test_opt(sb, GRPID) && (def_mount_opts & EXT2_DEFM_BSDGROUPS))
            seq_puts(seq, ",nogrpid");
      if (sbi->s_resuid != EXT2_DEF_RESUID ||
          le16_to_cpu(es->s_def_resuid) != EXT2_DEF_RESUID) {
            seq_printf(seq, ",resuid=%u", sbi->s_resuid);
      }
      if (sbi->s_resgid != EXT2_DEF_RESGID ||
          le16_to_cpu(es->s_def_resgid) != EXT2_DEF_RESGID) {
            seq_printf(seq, ",resgid=%u", sbi->s_resgid);
      }
      if (test_opt(sb, ERRORS_CONT)) {
            int def_errors = le16_to_cpu(es->s_errors);

            if (def_errors == EXT2_ERRORS_PANIC ||
                def_errors == EXT2_ERRORS_RO) {
                  seq_puts(seq, ",errors=continue");
            }
      }
      if (test_opt(sb, ERRORS_RO))
            seq_puts(seq, ",errors=remount-ro");
      if (test_opt(sb, ERRORS_PANIC))
            seq_puts(seq, ",errors=panic");
      if (test_opt(sb, NO_UID32))
            seq_puts(seq, ",nouid32");
      if (test_opt(sb, DEBUG))
            seq_puts(seq, ",debug");
      if (test_opt(sb, OLDALLOC))
            seq_puts(seq, ",oldalloc");

#ifdef CONFIG_EXT2_FS_XATTR
      if (test_opt(sb, XATTR_USER))
            seq_puts(seq, ",user_xattr");
      if (!test_opt(sb, XATTR_USER) &&
          (def_mount_opts & EXT2_DEFM_XATTR_USER)) {
            seq_puts(seq, ",nouser_xattr");
      }
#endif

#ifdef CONFIG_EXT2_FS_POSIX_ACL
      if (test_opt(sb, POSIX_ACL))
            seq_puts(seq, ",acl");
      if (!test_opt(sb, POSIX_ACL) && (def_mount_opts & EXT2_DEFM_ACL))
            seq_puts(seq, ",noacl");
#endif

      if (test_opt(sb, NOBH))
            seq_puts(seq, ",nobh");

#if defined(CONFIG_QUOTA)
      if (sbi->s_mount_opt & EXT2_MOUNT_USRQUOTA)
            seq_puts(seq, ",usrquota");

      if (sbi->s_mount_opt & EXT2_MOUNT_GRPQUOTA)
            seq_puts(seq, ",grpquota");
#endif

#if defined(CONFIG_EXT2_FS_XIP)
      if (sbi->s_mount_opt & EXT2_MOUNT_XIP)
            seq_puts(seq, ",xip");
#endif

      return 0;
}

#ifdef CONFIG_QUOTA
static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data, size_t len, loff_t off);
static ssize_t ext2_quota_write(struct super_block *sb, int type, const char *data, size_t len, loff_t off);
#endif

static const struct super_operations ext2_sops = {
      .alloc_inode      = ext2_alloc_inode,
      .destroy_inode    = ext2_destroy_inode,
      .read_inode = ext2_read_inode,
      .write_inode      = ext2_write_inode,
      .delete_inode     = ext2_delete_inode,
      .put_super  = ext2_put_super,
      .write_super      = ext2_write_super,
      .statfs           = ext2_statfs,
      .remount_fs = ext2_remount,
      .clear_inode      = ext2_clear_inode,
      .show_options     = ext2_show_options,
#ifdef CONFIG_QUOTA
      .quota_read = ext2_quota_read,
      .quota_write      = ext2_quota_write,
#endif
};

static struct inode *ext2_nfs_get_inode(struct super_block *sb,
            u64 ino, u32 generation)
{
      struct inode *inode;

      if (ino < EXT2_FIRST_INO(sb) && ino != EXT2_ROOT_INO)
            return ERR_PTR(-ESTALE);
      if (ino > le32_to_cpu(EXT2_SB(sb)->s_es->s_inodes_count))
            return ERR_PTR(-ESTALE);

      /* iget isn't really right if the inode is currently unallocated!!
       * ext2_read_inode currently does appropriate checks, but
       * it might be "neater" to call ext2_get_inode first and check
       * if the inode is valid.....
       */
      inode = iget(sb, ino);
      if (inode == NULL)
            return ERR_PTR(-ENOMEM);
      if (is_bad_inode(inode) ||
          (generation && inode->i_generation != generation)) {
            /* we didn't find the right inode.. */
            iput(inode);
            return ERR_PTR(-ESTALE);
      }
      return inode;
}

static struct dentry *ext2_fh_to_dentry(struct super_block *sb, struct fid *fid,
            int fh_len, int fh_type)
{
      return generic_fh_to_dentry(sb, fid, fh_len, fh_type,
                            ext2_nfs_get_inode);
}

static struct dentry *ext2_fh_to_parent(struct super_block *sb, struct fid *fid,
            int fh_len, int fh_type)
{
      return generic_fh_to_parent(sb, fid, fh_len, fh_type,
                            ext2_nfs_get_inode);
}

/* Yes, most of these are left as NULL!!
 * A NULL value implies the default, which works with ext2-like file
 * systems, but can be improved upon.
 * Currently only get_parent is required.
 */
static const struct export_operations ext2_export_ops = {
      .fh_to_dentry = ext2_fh_to_dentry,
      .fh_to_parent = ext2_fh_to_parent,
      .get_parent = ext2_get_parent,
};

static unsigned long get_sb_block(void **data)
{
      unsigned long     sb_block;
      char        *options = (char *) *data;

      if (!options || strncmp(options, "sb=", 3) != 0)
            return 1;   /* Default location */
      options += 3;
      sb_block = simple_strtoul(options, &options, 0);
      if (*options && *options != ',') {
            printk("EXT2-fs: Invalid sb specification: %s\n",
                   (char *) *data);
            return 1;
      }
      if (*options == ',')
            options++;
      *data = (void *) options;
      return sb_block;
}

enum {
      Opt_bsd_df, Opt_minix_df, Opt_grpid, Opt_nogrpid,
      Opt_resgid, Opt_resuid, Opt_sb, Opt_err_cont, Opt_err_panic,
      Opt_err_ro, Opt_nouid32, Opt_nocheck, Opt_debug,
      Opt_oldalloc, Opt_orlov, Opt_nobh, Opt_user_xattr, Opt_nouser_xattr,
      Opt_acl, Opt_noacl, Opt_xip, Opt_ignore, Opt_err, Opt_quota,
      Opt_usrquota, Opt_grpquota, Opt_reservation, Opt_noreservation
};

static match_table_t tokens = {
      {Opt_bsd_df, "bsddf"},
      {Opt_minix_df, "minixdf"},
      {Opt_grpid, "grpid"},
      {Opt_grpid, "bsdgroups"},
      {Opt_nogrpid, "nogrpid"},
      {Opt_nogrpid, "sysvgroups"},
      {Opt_resgid, "resgid=%u"},
      {Opt_resuid, "resuid=%u"},
      {Opt_sb, "sb=%u"},
      {Opt_err_cont, "errors=continue"},
      {Opt_err_panic, "errors=panic"},
      {Opt_err_ro, "errors=remount-ro"},
      {Opt_nouid32, "nouid32"},
      {Opt_nocheck, "check=none"},
      {Opt_nocheck, "nocheck"},
      {Opt_debug, "debug"},
      {Opt_oldalloc, "oldalloc"},
      {Opt_orlov, "orlov"},
      {Opt_nobh, "nobh"},
      {Opt_user_xattr, "user_xattr"},
      {Opt_nouser_xattr, "nouser_xattr"},
      {Opt_acl, "acl"},
      {Opt_noacl, "noacl"},
      {Opt_xip, "xip"},
      {Opt_grpquota, "grpquota"},
      {Opt_ignore, "noquota"},
      {Opt_quota, "quota"},
      {Opt_usrquota, "usrquota"},
      {Opt_reservation, "reservation"},
      {Opt_noreservation, "noreservation"},
      {Opt_err, NULL}
};

static int parse_options (char * options,
                    struct ext2_sb_info *sbi)
{
      char * p;
      substring_t args[MAX_OPT_ARGS];
      int option;

      if (!options)
            return 1;

      while ((p = strsep (&options, ",")) != NULL) {
            int token;
            if (!*p)
                  continue;

            token = match_token(p, tokens, args);
            switch (token) {
            case Opt_bsd_df:
                  clear_opt (sbi->s_mount_opt, MINIX_DF);
                  break;
            case Opt_minix_df:
                  set_opt (sbi->s_mount_opt, MINIX_DF);
                  break;
            case Opt_grpid:
                  set_opt (sbi->s_mount_opt, GRPID);
                  break;
            case Opt_nogrpid:
                  clear_opt (sbi->s_mount_opt, GRPID);
                  break;
            case Opt_resuid:
                  if (match_int(&args[0], &option))
                        return 0;
                  sbi->s_resuid = option;
                  break;
            case Opt_resgid:
                  if (match_int(&args[0], &option))
                        return 0;
                  sbi->s_resgid = option;
                  break;
            case Opt_sb:
                  /* handled by get_sb_block() instead of here */
                  /* *sb_block = match_int(&args[0]); */
                  break;
            case Opt_err_panic:
                  clear_opt (sbi->s_mount_opt, ERRORS_CONT);
                  clear_opt (sbi->s_mount_opt, ERRORS_RO);
                  set_opt (sbi->s_mount_opt, ERRORS_PANIC);
                  break;
            case Opt_err_ro:
                  clear_opt (sbi->s_mount_opt, ERRORS_CONT);
                  clear_opt (sbi->s_mount_opt, ERRORS_PANIC);
                  set_opt (sbi->s_mount_opt, ERRORS_RO);
                  break;
            case Opt_err_cont:
                  clear_opt (sbi->s_mount_opt, ERRORS_RO);
                  clear_opt (sbi->s_mount_opt, ERRORS_PANIC);
                  set_opt (sbi->s_mount_opt, ERRORS_CONT);
                  break;
            case Opt_nouid32:
                  set_opt (sbi->s_mount_opt, NO_UID32);
                  break;
            case Opt_nocheck:
                  clear_opt (sbi->s_mount_opt, CHECK);
                  break;
            case Opt_debug:
                  set_opt (sbi->s_mount_opt, DEBUG);
                  break;
            case Opt_oldalloc:
                  set_opt (sbi->s_mount_opt, OLDALLOC);
                  break;
            case Opt_orlov:
                  clear_opt (sbi->s_mount_opt, OLDALLOC);
                  break;
            case Opt_nobh:
                  set_opt (sbi->s_mount_opt, NOBH);
                  break;
#ifdef CONFIG_EXT2_FS_XATTR
            case Opt_user_xattr:
                  set_opt (sbi->s_mount_opt, XATTR_USER);
                  break;
            case Opt_nouser_xattr:
                  clear_opt (sbi->s_mount_opt, XATTR_USER);
                  break;
#else
            case Opt_user_xattr:
            case Opt_nouser_xattr:
                  printk("EXT2 (no)user_xattr options not supported\n");
                  break;
#endif
#ifdef CONFIG_EXT2_FS_POSIX_ACL
            case Opt_acl:
                  set_opt(sbi->s_mount_opt, POSIX_ACL);
                  break;
            case Opt_noacl:
                  clear_opt(sbi->s_mount_opt, POSIX_ACL);
                  break;
#else
            case Opt_acl:
            case Opt_noacl:
                  printk("EXT2 (no)acl options not supported\n");
                  break;
#endif
            case Opt_xip:
#ifdef CONFIG_EXT2_FS_XIP
                  set_opt (sbi->s_mount_opt, XIP);
#else
                  printk("EXT2 xip option not supported\n");
#endif
                  break;

#if defined(CONFIG_QUOTA)
            case Opt_quota:
            case Opt_usrquota:
                  set_opt(sbi->s_mount_opt, USRQUOTA);
                  break;

            case Opt_grpquota:
                  set_opt(sbi->s_mount_opt, GRPQUOTA);
                  break;
#else
            case Opt_quota:
            case Opt_usrquota:
            case Opt_grpquota:
                  printk(KERN_ERR
                        "EXT2-fs: quota operations not supported.\n");

                  break;
#endif

            case Opt_reservation:
                  set_opt(sbi->s_mount_opt, RESERVATION);
                  printk("reservations ON\n");
                  break;
            case Opt_noreservation:
                  clear_opt(sbi->s_mount_opt, RESERVATION);
                  printk("reservations OFF\n");
                  break;
            case Opt_ignore:
                  break;
            default:
                  return 0;
            }
      }
      return 1;
}

static int ext2_setup_super (struct super_block * sb,
                        struct ext2_super_block * es,
                        int read_only)
{
      int res = 0;
      struct ext2_sb_info *sbi = EXT2_SB(sb);

      if (le32_to_cpu(es->s_rev_level) > EXT2_MAX_SUPP_REV) {
            printk ("EXT2-fs warning: revision level too high, "
                  "forcing read-only mode\n");
            res = MS_RDONLY;
      }
      if (read_only)
            return res;
      if (!(sbi->s_mount_state & EXT2_VALID_FS))
            printk ("EXT2-fs warning: mounting unchecked fs, "
                  "running e2fsck is recommended\n");
      else if ((sbi->s_mount_state & EXT2_ERROR_FS))
            printk ("EXT2-fs warning: mounting fs with errors, "
                  "running e2fsck is recommended\n");
      else if ((__s16) le16_to_cpu(es->s_max_mnt_count) >= 0 &&
             le16_to_cpu(es->s_mnt_count) >=
             (unsigned short) (__s16) le16_to_cpu(es->s_max_mnt_count))
            printk ("EXT2-fs warning: maximal mount count reached, "
                  "running e2fsck is recommended\n");
      else if (le32_to_cpu(es->s_checkinterval) &&
            (le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= get_seconds()))
            printk ("EXT2-fs warning: checktime reached, "
                  "running e2fsck is recommended\n");
      if (!le16_to_cpu(es->s_max_mnt_count))
            es->s_max_mnt_count = cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
      es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
      ext2_write_super(sb);
      if (test_opt (sb, DEBUG))
            printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
                  "bpg=%lu, ipg=%lu, mo=%04lx]\n",
                  EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
                  sbi->s_frag_size,
                  sbi->s_groups_count,
                  EXT2_BLOCKS_PER_GROUP(sb),
                  EXT2_INODES_PER_GROUP(sb),
                  sbi->s_mount_opt);
      return res;
}

static int ext2_check_descriptors (struct super_block * sb)
{
      int i;
      int desc_block = 0;
      struct ext2_sb_info *sbi = EXT2_SB(sb);
      unsigned long first_block = le32_to_cpu(sbi->s_es->s_first_data_block);
      unsigned long last_block;
      struct ext2_group_desc * gdp = NULL;

      ext2_debug ("Checking group descriptors");

      for (i = 0; i < sbi->s_groups_count; i++)
      {
            if (i == sbi->s_groups_count - 1)
                  last_block = le32_to_cpu(sbi->s_es->s_blocks_count) - 1;
            else
                  last_block = first_block +
                        (EXT2_BLOCKS_PER_GROUP(sb) - 1);

            if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
                  gdp = (struct ext2_group_desc *) sbi->s_group_desc[desc_block++]->b_data;
            if (le32_to_cpu(gdp->bg_block_bitmap) < first_block ||
                le32_to_cpu(gdp->bg_block_bitmap) > last_block)
            {
                  ext2_error (sb, "ext2_check_descriptors",
                            "Block bitmap for group %d"
                            " not in group (block %lu)!",
                            i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
                  return 0;
            }
            if (le32_to_cpu(gdp->bg_inode_bitmap) < first_block ||
                le32_to_cpu(gdp->bg_inode_bitmap) > last_block)
            {
                  ext2_error (sb, "ext2_check_descriptors",
                            "Inode bitmap for group %d"
                            " not in group (block %lu)!",
                            i, (unsigned long) le32_to_cpu(gdp->bg_inode_bitmap));
                  return 0;
            }
            if (le32_to_cpu(gdp->bg_inode_table) < first_block ||
                le32_to_cpu(gdp->bg_inode_table) + sbi->s_itb_per_group - 1 >
                last_block)
            {
                  ext2_error (sb, "ext2_check_descriptors",
                            "Inode table for group %d"
                            " not in group (block %lu)!",
                            i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
                  return 0;
            }
            first_block += EXT2_BLOCKS_PER_GROUP(sb);
            gdp++;
      }
      return 1;
}

/*
 * Maximal file size.  There is a direct, and {,double-,triple-}indirect
 * block limit, and also a limit of (2^32 - 1) 512-byte sectors in i_blocks.
 * We need to be 1 filesystem block less than the 2^32 sector limit.
 */
static loff_t ext2_max_size(int bits)
{
      loff_t res = EXT2_NDIR_BLOCKS;
      /* This constant is calculated to be the largest file size for a
       * dense, 4k-blocksize file such that the total number of
       * sectors in the file, including data and all indirect blocks,
       * does not exceed 2^32. */
      const loff_t upper_limit = 0x1ff7fffd000LL;

      res += 1LL << (bits-2);
      res += 1LL << (2*(bits-2));
      res += 1LL << (3*(bits-2));
      res <<= bits;
      if (res > upper_limit)
            res = upper_limit;
      return res;
}

static unsigned long descriptor_loc(struct super_block *sb,
                            unsigned long logic_sb_block,
                            int nr)
{
      struct ext2_sb_info *sbi = EXT2_SB(sb);
      unsigned long bg, first_data_block, first_meta_bg;
      int has_super = 0;
      
      first_data_block = le32_to_cpu(sbi->s_es->s_first_data_block);
      first_meta_bg = le32_to_cpu(sbi->s_es->s_first_meta_bg);

      if (!EXT2_HAS_INCOMPAT_FEATURE(sb, EXT2_FEATURE_INCOMPAT_META_BG) ||
          nr < first_meta_bg)
            return (logic_sb_block + nr + 1);
      bg = sbi->s_desc_per_block * nr;
      if (ext2_bg_has_super(sb, bg))
            has_super = 1;
      return (first_data_block + has_super + (bg * sbi->s_blocks_per_group));
}

static int ext2_fill_super(struct super_block *sb, void *data, int silent)
{
      struct buffer_head * bh;
      struct ext2_sb_info * sbi;
      struct ext2_super_block * es;
      struct inode *root;
      unsigned long block;
      unsigned long sb_block = get_sb_block(&data);
      unsigned long logic_sb_block;
      unsigned long offset = 0;
      unsigned long def_mount_opts;
      int blocksize = BLOCK_SIZE;
      int db_count;
      int i, j;
      __le32 features;
      int err;

      sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
      if (!sbi)
            return -ENOMEM;
      sb->s_fs_info = sbi;
      sbi->s_sb_block = sb_block;

      /*
       * See what the current blocksize for the device is, and
       * use that as the blocksize.  Otherwise (or if the blocksize
       * is smaller than the default) use the default.
       * This is important for devices that have a hardware
       * sectorsize that is larger than the default.
       */
      blocksize = sb_min_blocksize(sb, BLOCK_SIZE);
      if (!blocksize) {
            printk ("EXT2-fs: unable to set blocksize\n");
            goto failed_sbi;
      }

      /*
       * If the superblock doesn't start on a hardware sector boundary,
       * calculate the offset.  
       */
      if (blocksize != BLOCK_SIZE) {
            logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
            offset = (sb_block*BLOCK_SIZE) % blocksize;
      } else {
            logic_sb_block = sb_block;
      }

      if (!(bh = sb_bread(sb, logic_sb_block))) {
            printk ("EXT2-fs: unable to read superblock\n");
            goto failed_sbi;
      }
      /*
       * Note: s_es must be initialized as soon as possible because
       *       some ext2 macro-instructions depend on its value
       */
      es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
      sbi->s_es = es;
      sb->s_magic = le16_to_cpu(es->s_magic);

      if (sb->s_magic != EXT2_SUPER_MAGIC)
            goto cantfind_ext2;

      /* Set defaults before we parse the mount options */
      def_mount_opts = le32_to_cpu(es->s_default_mount_opts);
      if (def_mount_opts & EXT2_DEFM_DEBUG)
            set_opt(sbi->s_mount_opt, DEBUG);
      if (def_mount_opts & EXT2_DEFM_BSDGROUPS)
            set_opt(sbi->s_mount_opt, GRPID);
      if (def_mount_opts & EXT2_DEFM_UID16)
            set_opt(sbi->s_mount_opt, NO_UID32);
#ifdef CONFIG_EXT2_FS_XATTR
      if (def_mount_opts & EXT2_DEFM_XATTR_USER)
            set_opt(sbi->s_mount_opt, XATTR_USER);
#endif
#ifdef CONFIG_EXT2_FS_POSIX_ACL
      if (def_mount_opts & EXT2_DEFM_ACL)
            set_opt(sbi->s_mount_opt, POSIX_ACL);
#endif
      
      if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_PANIC)
            set_opt(sbi->s_mount_opt, ERRORS_PANIC);
      else if (le16_to_cpu(sbi->s_es->s_errors) == EXT2_ERRORS_RO)
            set_opt(sbi->s_mount_opt, ERRORS_RO);
      else
            set_opt(sbi->s_mount_opt, ERRORS_CONT);

      sbi->s_resuid = le16_to_cpu(es->s_def_resuid);
      sbi->s_resgid = le16_to_cpu(es->s_def_resgid);
      
      set_opt(sbi->s_mount_opt, RESERVATION);

      if (!parse_options ((char *) data, sbi))
            goto failed_mount;

      sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
            ((EXT2_SB(sb)->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ?
             MS_POSIXACL : 0);

      ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
                            EXT2_MOUNT_XIP if not */

      if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV &&
          (EXT2_HAS_COMPAT_FEATURE(sb, ~0U) ||
           EXT2_HAS_RO_COMPAT_FEATURE(sb, ~0U) ||
           EXT2_HAS_INCOMPAT_FEATURE(sb, ~0U)))
            printk("EXT2-fs warning: feature flags set on rev 0 fs, "
                   "running e2fsck is recommended\n");
      /*
       * Check feature flags regardless of the revision level, since we
       * previously didn't change the revision level when setting the flags,
       * so there is a chance incompat flags are set on a rev 0 filesystem.
       */
      features = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP);
      if (features) {
            printk("EXT2-fs: %s: couldn't mount because of "
                   "unsupported optional features (%x).\n",
                   sb->s_id, le32_to_cpu(features));
            goto failed_mount;
      }
      if (!(sb->s_flags & MS_RDONLY) &&
          (features = EXT2_HAS_RO_COMPAT_FEATURE(sb, ~EXT2_FEATURE_RO_COMPAT_SUPP))){
            printk("EXT2-fs: %s: couldn't mount RDWR because of "
                   "unsupported optional features (%x).\n",
                   sb->s_id, le32_to_cpu(features));
            goto failed_mount;
      }

      blocksize = BLOCK_SIZE << le32_to_cpu(sbi->s_es->s_log_block_size);

      if ((ext2_use_xip(sb)) && ((blocksize != PAGE_SIZE) ||
                          (sb->s_blocksize != blocksize))) {
            if (!silent)
                  printk("XIP: Unsupported blocksize\n");
            goto failed_mount;
      }

      /* If the blocksize doesn't match, re-read the thing.. */
      if (sb->s_blocksize != blocksize) {
            brelse(bh);

            if (!sb_set_blocksize(sb, blocksize)) {
                  printk(KERN_ERR "EXT2-fs: blocksize too small for device.\n");
                  goto failed_sbi;
            }

            logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
            offset = (sb_block*BLOCK_SIZE) % blocksize;
            bh = sb_bread(sb, logic_sb_block);
            if(!bh) {
                  printk("EXT2-fs: Couldn't read superblock on "
                         "2nd try.\n");
                  goto failed_sbi;
            }
            es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
            sbi->s_es = es;
            if (es->s_magic != cpu_to_le16(EXT2_SUPER_MAGIC)) {
                  printk ("EXT2-fs: Magic mismatch, very weird !\n");
                  goto failed_mount;
            }
      }

      sb->s_maxbytes = ext2_max_size(sb->s_blocksize_bits);

      if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
            sbi->s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
            sbi->s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
      } else {
            sbi->s_inode_size = le16_to_cpu(es->s_inode_size);
            sbi->s_first_ino = le32_to_cpu(es->s_first_ino);
            if ((sbi->s_inode_size < EXT2_GOOD_OLD_INODE_SIZE) ||
                !is_power_of_2(sbi->s_inode_size) ||
                (sbi->s_inode_size > blocksize)) {
                  printk ("EXT2-fs: unsupported inode size: %d\n",
                        sbi->s_inode_size);
                  goto failed_mount;
            }
      }

      sbi->s_frag_size = EXT2_MIN_FRAG_SIZE <<
                           le32_to_cpu(es->s_log_frag_size);
      if (sbi->s_frag_size == 0)
            goto cantfind_ext2;
      sbi->s_frags_per_block = sb->s_blocksize / sbi->s_frag_size;

      sbi->s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
      sbi->s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
      sbi->s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);

      if (EXT2_INODE_SIZE(sb) == 0)
            goto cantfind_ext2;
      sbi->s_inodes_per_block = sb->s_blocksize / EXT2_INODE_SIZE(sb);
      if (sbi->s_inodes_per_block == 0 || sbi->s_inodes_per_group == 0)
            goto cantfind_ext2;
      sbi->s_itb_per_group = sbi->s_inodes_per_group /
                              sbi->s_inodes_per_block;
      sbi->s_desc_per_block = sb->s_blocksize /
                              sizeof (struct ext2_group_desc);
      sbi->s_sbh = bh;
      sbi->s_mount_state = le16_to_cpu(es->s_state);
      sbi->s_addr_per_block_bits =
            ilog2 (EXT2_ADDR_PER_BLOCK(sb));
      sbi->s_desc_per_block_bits =
            ilog2 (EXT2_DESC_PER_BLOCK(sb));

      if (sb->s_magic != EXT2_SUPER_MAGIC)
            goto cantfind_ext2;

      if (sb->s_blocksize != bh->b_size) {
            if (!silent)
                  printk ("VFS: Unsupported blocksize on dev "
                        "%s.\n", sb->s_id);
            goto failed_mount;
      }

      if (sb->s_blocksize != sbi->s_frag_size) {
            printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
                  sbi->s_frag_size, sb->s_blocksize);
            goto failed_mount;
      }

      if (sbi->s_blocks_per_group > sb->s_blocksize * 8) {
            printk ("EXT2-fs: #blocks per group too big: %lu\n",
                  sbi->s_blocks_per_group);
            goto failed_mount;
      }
      if (sbi->s_frags_per_group > sb->s_blocksize * 8) {
            printk ("EXT2-fs: #fragments per group too big: %lu\n",
                  sbi->s_frags_per_group);
            goto failed_mount;
      }
      if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {
            printk ("EXT2-fs: #inodes per group too big: %lu\n",
                  sbi->s_inodes_per_group);
            goto failed_mount;
      }

      if (EXT2_BLOCKS_PER_GROUP(sb) == 0)
            goto cantfind_ext2;
      sbi->s_groups_count = ((le32_to_cpu(es->s_blocks_count) -
                        le32_to_cpu(es->s_first_data_block) - 1)
                              / EXT2_BLOCKS_PER_GROUP(sb)) + 1;
      db_count = (sbi->s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
               EXT2_DESC_PER_BLOCK(sb);
      sbi->s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
      if (sbi->s_group_desc == NULL) {
            printk ("EXT2-fs: not enough memory\n");
            goto failed_mount;
      }
      bgl_lock_init(&sbi->s_blockgroup_lock);
      sbi->s_debts = kcalloc(sbi->s_groups_count, sizeof(*sbi->s_debts), GFP_KERNEL);
      if (!sbi->s_debts) {
            printk ("EXT2-fs: not enough memory\n");
            goto failed_mount_group_desc;
      }
      for (i = 0; i < db_count; i++) {
            block = descriptor_loc(sb, logic_sb_block, i);
            sbi->s_group_desc[i] = sb_bread(sb, block);
            if (!sbi->s_group_desc[i]) {
                  for (j = 0; j < i; j++)
                        brelse (sbi->s_group_desc[j]);
                  printk ("EXT2-fs: unable to read group descriptors\n");
                  goto failed_mount_group_desc;
            }
      }
      if (!ext2_check_descriptors (sb)) {
            printk ("EXT2-fs: group descriptors corrupted!\n");
            goto failed_mount2;
      }
      sbi->s_gdb_count = db_count;
      get_random_bytes(&sbi->s_next_generation, sizeof(u32));
      spin_lock_init(&sbi->s_next_gen_lock);

      /* per fileystem reservation list head & lock */
      spin_lock_init(&sbi->s_rsv_window_lock);
      sbi->s_rsv_window_root = RB_ROOT;
      /*
       * Add a single, static dummy reservation to the start of the
       * reservation window list --- it gives us a placeholder for
       * append-at-start-of-list which makes the allocation logic
       * _much_ simpler.
       */
      sbi->s_rsv_window_head.rsv_start = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
      sbi->s_rsv_window_head.rsv_end = EXT2_RESERVE_WINDOW_NOT_ALLOCATED;
      sbi->s_rsv_window_head.rsv_alloc_hit = 0;
      sbi->s_rsv_window_head.rsv_goal_size = 0;
      ext2_rsv_window_add(sb, &sbi->s_rsv_window_head);

      err = percpu_counter_init(&sbi->s_freeblocks_counter,
                        ext2_count_free_blocks(sb));
      if (!err) {
            err = percpu_counter_init(&sbi->s_freeinodes_counter,
                        ext2_count_free_inodes(sb));
      }
      if (!err) {
            err = percpu_counter_init(&sbi->s_dirs_counter,
                        ext2_count_dirs(sb));
      }
      if (err) {
            printk(KERN_ERR "EXT2-fs: insufficient memory\n");
            goto failed_mount3;
      }
      /*
       * set up enough so that it can read an inode
       */
      sb->s_op = &ext2_sops;
      sb->s_export_op = &ext2_export_ops;
      sb->s_xattr = ext2_xattr_handlers;
      root = iget(sb, EXT2_ROOT_INO);
      sb->s_root = d_alloc_root(root);
      if (!sb->s_root) {
            iput(root);
            printk(KERN_ERR "EXT2-fs: get root inode failed\n");
            goto failed_mount3;
      }
      if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {
            dput(sb->s_root);
            sb->s_root = NULL;
            printk(KERN_ERR "EXT2-fs: corrupt root inode, run e2fsck\n");
            goto failed_mount3;
      }
      if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))
            ext2_warning(sb, __FUNCTION__,
                  "mounting ext3 filesystem as ext2");
      ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
      return 0;

cantfind_ext2:
      if (!silent)
            printk("VFS: Can't find an ext2 filesystem on dev %s.\n",
                   sb->s_id);
      goto failed_mount;
failed_mount3:
      percpu_counter_destroy(&sbi->s_freeblocks_counter);
      percpu_counter_destroy(&sbi->s_freeinodes_counter);
      percpu_counter_destroy(&sbi->s_dirs_counter);
failed_mount2:
      for (i = 0; i < db_count; i++)
            brelse(sbi->s_group_desc[i]);
failed_mount_group_desc:
      kfree(sbi->s_group_desc);
      kfree(sbi->s_debts);
failed_mount:
      brelse(bh);
failed_sbi:
      sb->s_fs_info = NULL;
      kfree(sbi);
      return -EINVAL;
}

static void ext2_commit_super (struct super_block * sb,
                         struct ext2_super_block * es)
{
      es->s_wtime = cpu_to_le32(get_seconds());
      mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
      sb->s_dirt = 0;
}

static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es)
{
      es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
      es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
      es->s_wtime = cpu_to_le32(get_seconds());
      mark_buffer_dirty(EXT2_SB(sb)->s_sbh);
      sync_dirty_buffer(EXT2_SB(sb)->s_sbh);
      sb->s_dirt = 0;
}

/*
 * In the second extended file system, it is not necessary to
 * write the super block since we use a mapping of the
 * disk super block in a buffer.
 *
 * However, this function is still used to set the fs valid
 * flags to 0.  We need to set this flag to 0 since the fs
 * may have been checked while mounted and e2fsck may have
 * set s_state to EXT2_VALID_FS after some corrections.
 */

void ext2_write_super (struct super_block * sb)
{
      struct ext2_super_block * es;
      lock_kernel();
      if (!(sb->s_flags & MS_RDONLY)) {
            es = EXT2_SB(sb)->s_es;

            if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
                  ext2_debug ("setting valid to 0\n");
                  es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) &
                                      ~EXT2_VALID_FS);
                  es->s_free_blocks_count = cpu_to_le32(ext2_count_free_blocks(sb));
                  es->s_free_inodes_count = cpu_to_le32(ext2_count_free_inodes(sb));
                  es->s_mtime = cpu_to_le32(get_seconds());
                  ext2_sync_super(sb, es);
            } else
                  ext2_commit_super (sb, es);
      }
      sb->s_dirt = 0;
      unlock_kernel();
}

static int ext2_remount (struct super_block * sb, int * flags, char * data)
{
      struct ext2_sb_info * sbi = EXT2_SB(sb);
      struct ext2_super_block * es;
      unsigned long old_mount_opt = sbi->s_mount_opt;
      struct ext2_mount_options old_opts;
      unsigned long old_sb_flags;
      int err;

      /* Store the old options */
      old_sb_flags = sb->s_flags;
      old_opts.s_mount_opt = sbi->s_mount_opt;
      old_opts.s_resuid = sbi->s_resuid;
      old_opts.s_resgid = sbi->s_resgid;

      /*
       * Allow the "check" option to be passed as a remount option.
       */
      if (!parse_options (data, sbi)) {
            err = -EINVAL;
            goto restore_opts;
      }

      sb->s_flags = (sb->s_flags & ~MS_POSIXACL) |
            ((sbi->s_mount_opt & EXT2_MOUNT_POSIX_ACL) ? MS_POSIXACL : 0);

      ext2_xip_verify_sb(sb); /* see if bdev supports xip, unset
                            EXT2_MOUNT_XIP if not */

      if ((ext2_use_xip(sb)) && (sb->s_blocksize != PAGE_SIZE)) {
            printk("XIP: Unsupported blocksize\n");
            err = -EINVAL;
            goto restore_opts;
      }

      es = sbi->s_es;
      if (((sbi->s_mount_opt & EXT2_MOUNT_XIP) !=
          (old_mount_opt & EXT2_MOUNT_XIP)) &&
          invalidate_inodes(sb))
            ext2_warning(sb, __FUNCTION__, "busy inodes while remounting "\
                       "xip remain in cache (no functional problem)");
      if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY))
            return 0;
      if (*flags & MS_RDONLY) {
            if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||
                !(sbi->s_mount_state & EXT2_VALID_FS))
                  return 0;
            /*
             * OK, we are remounting a valid rw partition rdonly, so set
             * the rdonly flag and then mark the partition as valid again.
             */
            es->s_state = cpu_to_le16(sbi->s_mount_state);
            es->s_mtime = cpu_to_le32(get_seconds());
      } else {
            __le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
                                     ~EXT2_FEATURE_RO_COMPAT_SUPP);
            if (ret) {
                  printk("EXT2-fs: %s: couldn't remount RDWR because of "
                         "unsupported optional features (%x).\n",
                         sb->s_id, le32_to_cpu(ret));
                  err = -EROFS;
                  goto restore_opts;
            }
            /*
             * Mounting a RDONLY partition read-write, so reread and
             * store the current valid flag.  (It may have been changed
             * by e2fsck since we originally mounted the partition.)
             */
            sbi->s_mount_state = le16_to_cpu(es->s_state);
            if (!ext2_setup_super (sb, es, 0))
                  sb->s_flags &= ~MS_RDONLY;
      }
      ext2_sync_super(sb, es);
      return 0;
restore_opts:
      sbi->s_mount_opt = old_opts.s_mount_opt;
      sbi->s_resuid = old_opts.s_resuid;
      sbi->s_resgid = old_opts.s_resgid;
      sb->s_flags = old_sb_flags;
      return err;
}

static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf)
{
      struct super_block *sb = dentry->d_sb;
      struct ext2_sb_info *sbi = EXT2_SB(sb);
      struct ext2_super_block *es = sbi->s_es;
      u64 fsid;

      if (test_opt (sb, MINIX_DF))
            sbi->s_overhead_last = 0;
      else if (sbi->s_blocks_last != le32_to_cpu(es->s_blocks_count)) {
            unsigned long i, overhead = 0;
            smp_rmb();

            /*
             * Compute the overhead (FS structures). This is constant
             * for a given filesystem unless the number of block groups
             * changes so we cache the previous value until it does.
             */

            /*
             * All of the blocks before first_data_block are
             * overhead
             */
            overhead = le32_to_cpu(es->s_first_data_block);

            /*
             * Add the overhead attributed to the superblock and
             * block group descriptors.  If the sparse superblocks
             * feature is turned on, then not all groups have this.
             */
            for (i = 0; i < sbi->s_groups_count; i++)
                  overhead += ext2_bg_has_super(sb, i) +
                        ext2_bg_num_gdb(sb, i);

            /*
             * Every block group has an inode bitmap, a block
             * bitmap, and an inode table.
             */
            overhead += (sbi->s_groups_count *
                       (2 + sbi->s_itb_per_group));
            sbi->s_overhead_last = overhead;
            smp_wmb();
            sbi->s_blocks_last = le32_to_cpu(es->s_blocks_count);
      }

      buf->f_type = EXT2_SUPER_MAGIC;
      buf->f_bsize = sb->s_blocksize;
      buf->f_blocks = le32_to_cpu(es->s_blocks_count) - sbi->s_overhead_last;
      buf->f_bfree = ext2_count_free_blocks(sb);
      es->s_free_blocks_count = cpu_to_le32(buf->f_bfree);
      buf->f_bavail = buf->f_bfree - le32_to_cpu(es->s_r_blocks_count);
      if (buf->f_bfree < le32_to_cpu(es->s_r_blocks_count))
            buf->f_bavail = 0;
      buf->f_files = le32_to_cpu(es->s_inodes_count);
      buf->f_ffree = ext2_count_free_inodes(sb);
      es->s_free_inodes_count = cpu_to_le32(buf->f_ffree);
      buf->f_namelen = EXT2_NAME_LEN;
      fsid = le64_to_cpup((void *)es->s_uuid) ^
             le64_to_cpup((void *)es->s_uuid + sizeof(u64));
      buf->f_fsid.val[0] = fsid & 0xFFFFFFFFUL;
      buf->f_fsid.val[1] = (fsid >> 32) & 0xFFFFFFFFUL;
      return 0;
}

static int ext2_get_sb(struct file_system_type *fs_type,
      int flags, const char *dev_name, void *data, struct vfsmount *mnt)
{
      return get_sb_bdev(fs_type, flags, dev_name, data, ext2_fill_super, mnt);
}

#ifdef CONFIG_QUOTA

/* Read data from quotafile - avoid pagecache and such because we cannot afford
 * acquiring the locks... As quota files are never truncated and quota code
 * itself serializes the operations (and noone else should touch the files)
 * we don't have to be afraid of races */
static ssize_t ext2_quota_read(struct super_block *sb, int type, char *data,
                         size_t len, loff_t off)
{
      struct inode *inode = sb_dqopt(sb)->files[type];
      sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
      int err = 0;
      int offset = off & (sb->s_blocksize - 1);
      int tocopy;
      size_t toread;
      struct buffer_head tmp_bh;
      struct buffer_head *bh;
      loff_t i_size = i_size_read(inode);

      if (off > i_size)
            return 0;
      if (off+len > i_size)
            len = i_size-off;
      toread = len;
      while (toread > 0) {
            tocopy = sb->s_blocksize - offset < toread ?
                        sb->s_blocksize - offset : toread;

            tmp_bh.b_state = 0;
            err = ext2_get_block(inode, blk, &tmp_bh, 0);
            if (err < 0)
                  return err;
            if (!buffer_mapped(&tmp_bh))  /* A hole? */
                  memset(data, 0, tocopy);
            else {
                  bh = sb_bread(sb, tmp_bh.b_blocknr);
                  if (!bh)
                        return -EIO;
                  memcpy(data, bh->b_data+offset, tocopy);
                  brelse(bh);
            }
            offset = 0;
            toread -= tocopy;
            data += tocopy;
            blk++;
      }
      return len;
}

/* Write to quotafile */
static ssize_t ext2_quota_write(struct super_block *sb, int type,
                        const char *data, size_t len, loff_t off)
{
      struct inode *inode = sb_dqopt(sb)->files[type];
      sector_t blk = off >> EXT2_BLOCK_SIZE_BITS(sb);
      int err = 0;
      int offset = off & (sb->s_blocksize - 1);
      int tocopy;
      size_t towrite = len;
      struct buffer_head tmp_bh;
      struct buffer_head *bh;

      mutex_lock_nested(&inode->i_mutex, I_MUTEX_QUOTA);
      while (towrite > 0) {
            tocopy = sb->s_blocksize - offset < towrite ?
                        sb->s_blocksize - offset : towrite;

            tmp_bh.b_state = 0;
            err = ext2_get_block(inode, blk, &tmp_bh, 1);
            if (err < 0)
                  goto out;
            if (offset || tocopy != EXT2_BLOCK_SIZE(sb))
                  bh = sb_bread(sb, tmp_bh.b_blocknr);
            else
                  bh = sb_getblk(sb, tmp_bh.b_blocknr);
            if (!bh) {
                  err = -EIO;
                  goto out;
            }
            lock_buffer(bh);
            memcpy(bh->b_data+offset, data, tocopy);
            flush_dcache_page(bh->b_page);
            set_buffer_uptodate(bh);
            mark_buffer_dirty(bh);
            unlock_buffer(bh);
            brelse(bh);
            offset = 0;
            towrite -= tocopy;
            data += tocopy;
            blk++;
      }
out:
      if (len == towrite)
            return err;
      if (inode->i_size < off+len-towrite)
            i_size_write(inode, off+len-towrite);
      inode->i_version++;
      inode->i_mtime = inode->i_ctime = CURRENT_TIME;
      mark_inode_dirty(inode);
      mutex_unlock(&inode->i_mutex);
      return len - towrite;
}

#endif

static struct file_system_type ext2_fs_type = {
      .owner            = THIS_MODULE,
      .name       = "ext2",
      .get_sb           = ext2_get_sb,
      .kill_sb    = kill_block_super,
      .fs_flags   = FS_REQUIRES_DEV,
};

static int __init init_ext2_fs(void)
{
      int err = init_ext2_xattr();
      if (err)
            return err;
      err = init_inodecache();
      if (err)
            goto out1;
        err = register_filesystem(&ext2_fs_type);
      if (err)
            goto out;
      return 0;
out:
      destroy_inodecache();
out1:
      exit_ext2_xattr();
      return err;
}

static void __exit exit_ext2_fs(void)
{
      unregister_filesystem(&ext2_fs_type);
      destroy_inodecache();
      exit_ext2_xattr();
}

module_init(init_ext2_fs)
module_exit(exit_ext2_fs)

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