/*
   *  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/vfs.h>

  #include <linux/seq_file.h>
  #include <linux/mount.h>

  #include <linux/log2.h>

  #include <linux/quotaops.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, int wait);

  static int ext2_remount (struct super_block * sb, int * flags, char * data);

  static int ext2_statfs (struct dentry * dentry, struct kstatfs * buf);

  static int ext2_sync_fs(struct super_block *sb, int wait);

  void ext2_error(struct super_block *sb, const char *function,
  		const char *fmt, ...)

  {

  	struct va_format vaf;

  	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)) {

  		spin_lock(&sbi->s_lock);

  		sbi->s_mount_state |= EXT2_ERROR_FS;

  		es->s_state |= cpu_to_le16(EXT2_ERROR_FS);

  		spin_unlock(&sbi->s_lock);

  		ext2_sync_super(sb, es, 1);

  	}
  
  	va_start(args, fmt);

  
  	vaf.fmt = fmt;
  	vaf.va = &args;
  
  	printk(KERN_CRIT "EXT2-fs (%s): error: %s: %pV
  ",
  	       sb->s_id, function, &vaf);

  	va_end(args);
  
  	if (test_opt(sb, ERRORS_PANIC))

  		panic("EXT2-fs: panic from previous error
  ");

  	if (test_opt(sb, ERRORS_RO)) {

  		ext2_msg(sb, KERN_CRIT,
  			     "error: remounting filesystem read-only");

  		sb->s_flags |= MS_RDONLY;
  	}
  }

  void ext2_msg(struct super_block *sb, const char *prefix,
  		const char *fmt, ...)

  {

  	struct va_format vaf;

  	va_list args;
  
  	va_start(args, fmt);

  
  	vaf.fmt = fmt;
  	vaf.va = &args;
  
  	printk("%sEXT2-fs (%s): %pV
  ", prefix, sb->s_id, &vaf);

  	va_end(args);
  }

  /*
   * This must be called with sbi->s_lock held.
   */

  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_msg(sb, KERN_WARNING,
  		     "warning: 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);

  	dquot_disable(sb, -1, DQUOT_USAGE_ENABLED | DQUOT_LIMITS_ENABLED);

  	if (sb->s_dirt)
  		ext2_write_super(sb);

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

  		spin_lock(&sbi->s_lock);

  		es->s_state = cpu_to_le16(sbi->s_mount_state);

  		spin_unlock(&sbi->s_lock);

  		ext2_sync_super(sb, es, 1);

  	}
  	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->s_blockgroup_lock);

  	kfree(sbi);

  }

  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;

  	ei->i_block_alloc_info = NULL;

  	ei->vfs_inode.i_version = 1;
  	return &ei->vfs_inode;
  }

  static void ext2_i_callback(struct rcu_head *head)

  {

  	struct inode *inode = container_of(head, struct inode, i_rcu);

  	kmem_cache_free(ext2_inode_cachep, EXT2_I(inode));
  }

  static void ext2_destroy_inode(struct inode *inode)
  {
  	call_rcu(&inode->i_rcu, ext2_i_callback);
  }

  static void init_once(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 int ext2_show_options(struct seq_file *seq, struct dentry *root)

  {

  	struct super_block *sb = root->d_sb;

  	struct ext2_sb_info *sbi = EXT2_SB(sb);
  	struct ext2_super_block *es = sbi->s_es;
  	unsigned long def_mount_opts;

  	spin_lock(&sbi->s_lock);

  	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_RO)) {

  		int def_errors = le16_to_cpu(es->s_errors);
  
  		if (def_errors == EXT2_ERRORS_PANIC ||

  		    def_errors == EXT2_ERRORS_CONTINUE) {
  			seq_puts(seq, ",errors=remount-ro");

  		}
  	}

  	if (test_opt(sb, ERRORS_CONT))
  		seq_puts(seq, ",errors=continue");

  	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

  	if (!test_opt(sb, RESERVATION))
  		seq_puts(seq, ",noreservation");

  	spin_unlock(&sbi->s_lock);

  	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,

  	.write_inode	= ext2_write_inode,

  	.evict_inode	= ext2_evict_inode,

  	.put_super	= ext2_put_super,
  	.write_super	= ext2_write_super,

  	.sync_fs	= ext2_sync_fs,

  	.statfs		= ext2_statfs,
  	.remount_fs	= ext2_remount,

  	.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);

  	/*
  	 * ext2_iget isn't quite right if the inode is currently unallocated!
  	 * However ext2_iget currently does appropriate checks to handle stale
  	 * inodes so everything is OK.

  	 */

  	inode = ext2_iget(sb, ino);
  	if (IS_ERR(inode))
  		return ERR_CAST(inode);
  	if (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
  ",
  		       (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 const 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 super_block *sb)

  {

  	char *p;
  	struct ext2_sb_info *sbi = EXT2_SB(sb);

  	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:

  			ext2_msg(sb, KERN_INFO, "(no)user_xattr options"
  				"not supported");

  			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:

  			ext2_msg(sb, KERN_INFO,
  				"(no)acl options not supported");

  			break;
  #endif

  		case Opt_xip:
  #ifdef CONFIG_EXT2_FS_XIP
  			set_opt (sbi->s_mount_opt, XIP);
  #else

  			ext2_msg(sb, KERN_INFO, "xip option not supported");

  #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:

  			ext2_msg(sb, KERN_INFO,
  				"quota operations not supported");

  			break;
  #endif

  		case Opt_reservation:
  			set_opt(sbi->s_mount_opt, RESERVATION);

  			ext2_msg(sb, KERN_INFO, "reservations ON");

  			break;
  		case Opt_noreservation:
  			clear_opt(sbi->s_mount_opt, RESERVATION);

  			ext2_msg(sb, KERN_INFO, "reservations OFF");

  			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) {

  		ext2_msg(sb, KERN_ERR,
  			"error: revision level too high, "
  			"forcing read-only mode");

  		res = MS_RDONLY;
  	}
  	if (read_only)
  		return res;
  	if (!(sbi->s_mount_state & EXT2_VALID_FS))

  		ext2_msg(sb, KERN_WARNING,
  			"warning: mounting unchecked fs, "
  			"running e2fsck is recommended");

  	else if ((sbi->s_mount_state & EXT2_ERROR_FS))

  		ext2_msg(sb, KERN_WARNING,
  			"warning: mounting fs with errors, "
  			"running e2fsck is recommended");

  	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))

  		ext2_msg(sb, KERN_WARNING,
  			"warning: maximal mount count reached, "
  			"running e2fsck is recommended");

  	else if (le32_to_cpu(es->s_checkinterval) &&

  		(le32_to_cpu(es->s_lastcheck) +
  			le32_to_cpu(es->s_checkinterval) <= get_seconds()))
  		ext2_msg(sb, KERN_WARNING,
  			"warning: checktime reached, "
  			"running e2fsck is recommended");

  	if (!le16_to_cpu(es->s_max_mnt_count))
  		es->s_max_mnt_count = cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);

  	le16_add_cpu(&es->s_mnt_count, 1);

  	if (test_opt (sb, DEBUG))

  		ext2_msg(sb, KERN_INFO, "%s, %s, bs=%lu, fs=%lu, gc=%lu, "
  			"bpg=%lu, ipg=%lu, mo=%04lx]",

  			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;

  	struct ext2_sb_info *sbi = EXT2_SB(sb);

  
  	ext2_debug ("Checking group descriptors");

  	for (i = 0; i < sbi->s_groups_count; i++) {
  		struct ext2_group_desc *gdp = ext2_get_group_desc(sb, i, NULL);

  		ext2_fsblk_t first_block = ext2_group_first_block_no(sb, i);
  		ext2_fsblk_t last_block;

  		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 (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;
  		}

  	}
  	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;

  	int meta_blocks;
  	loff_t upper_limit;
  
  	/* This is calculated to be the largest file size for a
  	 * dense, file such that the total number of

  	 * sectors in the file, including data and all indirect blocks,

  	 * does not exceed 2^32 -1
  	 * __u32 i_blocks representing the total number of
  	 * 512 bytes blocks of the file
  	 */
  	upper_limit = (1LL << 32) - 1;
  
  	/* total blocks in file system block size */
  	upper_limit >>= (bits - 9);
  
  
  	/* indirect blocks */
  	meta_blocks = 1;
  	/* double indirect blocks */
  	meta_blocks += 1 + (1LL << (bits-2));
  	/* tripple indirect blocks */
  	meta_blocks += 1 + (1LL << (bits-2)) + (1LL << (2*(bits-2)));
  
  	upper_limit -= meta_blocks;
  	upper_limit <<= bits;

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

  
  	if (res > MAX_LFS_FILESIZE)
  		res = MAX_LFS_FILESIZE;

  	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_meta_bg;

  	int has_super = 0;
  	

  	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 ext2_group_first_block_no(sb, bg) + has_super;

  }
  
  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;

  	long ret = -EINVAL;

  	int blocksize = BLOCK_SIZE;
  	int db_count;
  	int i, j;
  	__le32 features;

  	int err;

  	err = -ENOMEM;

  	sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);

  	if (!sbi)

  		goto failed_unlock;

  
  	sbi->s_blockgroup_lock =
  		kzalloc(sizeof(struct blockgroup_lock), GFP_KERNEL);
  	if (!sbi->s_blockgroup_lock) {
  		kfree(sbi);

  		goto failed_unlock;

  	}

  	sb->s_fs_info = sbi;

  	sbi->s_sb_block = sb_block;

  	spin_lock_init(&sbi->s_lock);

  	/*
  	 * 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) {

  		ext2_msg(sb, KERN_ERR, "error: unable to set blocksize");

  		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))) {

  		ext2_msg(sb, KERN_ERR, "error: unable to read superblock");

  		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_CONTINUE)

  		set_opt(sbi->s_mount_opt, ERRORS_CONT);

  	else
  		set_opt(sbi->s_mount_opt, ERRORS_RO);

  
  	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, sb))

  		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)))

  		ext2_msg(sb, KERN_WARNING,
  			"warning: feature flags set on rev 0 fs, "
  			"running e2fsck is recommended");

  	/*
  	 * 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) {

  		ext2_msg(sb, KERN_ERR,	"error: couldn't mount because of "
  		       "unsupported optional features (%x)",
  			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))){

  		ext2_msg(sb, KERN_ERR, "error: couldn't mount RDWR because of "
  		       "unsupported optional features (%x)",
  		       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) {

  		if (!silent)

  			ext2_msg(sb, KERN_ERR,
  				"error: unsupported blocksize for xip");

  		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)) {

  			ext2_msg(sb, KERN_ERR,
  				"error: bad blocksize %d", blocksize);

  			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) {

  			ext2_msg(sb, KERN_ERR, "error: couldn't read"
  				"superblock on 2nd try");

  			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)) {

  			ext2_msg(sb, KERN_ERR, "error: magic mismatch");

  			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)) {

  			ext2_msg(sb, KERN_ERR,
  				"error: unsupported inode size: %d",

  				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)

  			ext2_msg(sb, KERN_ERR, "error: unsupported blocksize");

  		goto failed_mount;
  	}
  
  	if (sb->s_blocksize != sbi->s_frag_size) {

  		ext2_msg(sb, KERN_ERR,
  			"error: fragsize %lu != blocksize %lu"
  			"(not supported yet)",

  			sbi->s_frag_size, sb->s_blocksize);
  		goto failed_mount;
  	}
  
  	if (sbi->s_blocks_per_group > sb->s_blocksize * 8) {

  		ext2_msg(sb, KERN_ERR,
  			"error: #blocks per group too big: %lu",

  			sbi->s_blocks_per_group);
  		goto failed_mount;
  	}
  	if (sbi->s_frags_per_group > sb->s_blocksize * 8) {

  		ext2_msg(sb, KERN_ERR,
  			"error: #fragments per group too big: %lu",

  			sbi->s_frags_per_group);
  		goto failed_mount;
  	}
  	if (sbi->s_inodes_per_group > sb->s_blocksize * 8) {

  		ext2_msg(sb, KERN_ERR,
  			"error: #inodes per group too big: %lu",

  			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) {

  		ext2_msg(sb, KERN_ERR, "error: not enough memory");

  		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) {

  		ext2_msg(sb, KERN_ERR, "error: not enough memory");

  		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]);

  			ext2_msg(sb, KERN_ERR,
  				"error: unable to read group descriptors");

  			goto failed_mount_group_desc;
  		}
  	}
  	if (!ext2_check_descriptors (sb)) {

  		ext2_msg(sb, KERN_ERR, "group descriptors corrupted");

  		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) {

  		ext2_msg(sb, KERN_ERR, "error: insufficient memory");

  		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;

  
  #ifdef CONFIG_QUOTA
  	sb->dq_op = &dquot_operations;

  	sb->s_qcop = &dquot_quotactl_ops;

  #endif

  	root = ext2_iget(sb, EXT2_ROOT_INO);
  	if (IS_ERR(root)) {
  		ret = PTR_ERR(root);

  		goto failed_mount3;

  	}
  	if (!S_ISDIR(root->i_mode) || !root->i_blocks || !root->i_size) {

  		iput(root);

  		ext2_msg(sb, KERN_ERR, "error: corrupt root inode, run e2fsck");

  		goto failed_mount3;

  	}

  
  	sb->s_root = d_alloc_root(root);
  	if (!sb->s_root) {
  		iput(root);

  		ext2_msg(sb, KERN_ERR, "error: get root inode failed");

  		ret = -ENOMEM;
  		goto failed_mount3;
  	}

  	if (EXT2_HAS_COMPAT_FEATURE(sb, EXT3_FEATURE_COMPAT_HAS_JOURNAL))

  		ext2_msg(sb, KERN_WARNING,
  			"warning: mounting ext3 filesystem as ext2");

  	if (ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY))
  		sb->s_flags |= MS_RDONLY;
  	ext2_write_super(sb);

  	return 0;
  
  cantfind_ext2:
  	if (!silent)

  		ext2_msg(sb, KERN_ERR,
  			"error: can't find an ext2 filesystem on dev %s.",
  			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->s_blockgroup_lock);

  	kfree(sbi);

  failed_unlock:

  	return ret;

  }

  static void ext2_clear_super_error(struct super_block *sb)
  {
  	struct buffer_head *sbh = EXT2_SB(sb)->s_sbh;
  
  	if (buffer_write_io_error(sbh)) {
  		/*
  		 * Oh, dear.  A previous attempt to write the
  		 * superblock failed.  This could happen because the
  		 * USB device was yanked out.  Or it could happen to
  		 * be a transient write error and maybe the block will
  		 * be remapped.  Nothing we can do but to retry the
  		 * write and hope for the best.
  		 */

  		ext2_msg(sb, KERN_ERR,
  		       "previous I/O error to superblock detected
  ");

  		clear_buffer_write_io_error(sbh);
  		set_buffer_uptodate(sbh);
  	}
  }

  static void ext2_sync_super(struct super_block *sb, struct ext2_super_block *es,
  			    int wait)

  {

  	ext2_clear_super_error(sb);

  	spin_lock(&EXT2_SB(sb)->s_lock);

  	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());

  	/* unlock before we do IO */
  	spin_unlock(&EXT2_SB(sb)->s_lock);

  	mark_buffer_dirty(EXT2_SB(sb)->s_sbh);

  	if (wait)
  		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.
   */

  static int ext2_sync_fs(struct super_block *sb, int wait)

  {

  	struct ext2_sb_info *sbi = EXT2_SB(sb);

  	struct ext2_super_block *es = EXT2_SB(sb)->s_es;

  	spin_lock(&sbi->s_lock);

  	if (es->s_state & cpu_to_le16(EXT2_VALID_FS)) {
  		ext2_debug("setting valid to 0
  ");
  		es->s_state &= cpu_to_le16(~EXT2_VALID_FS);

  	}

  	spin_unlock(&sbi->s_lock);

  	ext2_sync_super(sb, es, wait);

  	return 0;
  }
  
  
  void ext2_write_super(struct super_block *sb)
  {
  	if (!(sb->s_flags & MS_RDONLY))
  		ext2_sync_fs(sb, 1);
  	else
  		sb->s_dirt = 0;

  }
  
  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;

  	spin_lock(&sbi->s_lock);

  	/* 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, sb)) {

  		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)) {

  		ext2_msg(sb, KERN_WARNING,
  			"warning: unsupported blocksize for xip");

  		err = -EINVAL;

  		goto restore_opts;
  	}

  	es = sbi->s_es;

  	if ((sbi->s_mount_opt ^ old_mount_opt) & EXT2_MOUNT_XIP) {

  		ext2_msg(sb, KERN_WARNING, "warning: refusing change of "
  			 "xip flag with busy inodes while remounting");

  		sbi->s_mount_opt &= ~EXT2_MOUNT_XIP;
  		sbi->s_mount_opt |= old_mount_opt & EXT2_MOUNT_XIP;
  	}

  	if ((*flags & MS_RDONLY) == (sb->s_flags & MS_RDONLY)) {

  		spin_unlock(&sbi->s_lock);

  		return 0;

  	}

  	if (*flags & MS_RDONLY) {
  		if (le16_to_cpu(es->s_state) & EXT2_VALID_FS ||

  		    !(sbi->s_mount_state & EXT2_VALID_FS)) {

  			spin_unlock(&sbi->s_lock);

  			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());

  		spin_unlock(&sbi->s_lock);

  		err = dquot_suspend(sb, -1);
  		if (err < 0) {

  			spin_lock(&sbi->s_lock);
  			goto restore_opts;
  		}

  		ext2_sync_super(sb, es, 1);

  	} else {
  		__le32 ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
  					       ~EXT2_FEATURE_RO_COMPAT_SUPP);
  		if (ret) {

  			ext2_msg(sb, KERN_WARNING,
  				"warning: couldn't remount RDWR because of "
  				"unsupported optional features (%x).",
  				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;

  		spin_unlock(&sbi->s_lock);

  		ext2_write_super(sb);

  		dquot_resume(sb, -1);

  	}

  	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;

  	spin_unlock(&sbi->s_lock);

  	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;

  	spin_lock(&sbi->s_lock);

  	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;

  	spin_unlock(&sbi->s_lock);

  	return 0;
  }

  static struct dentry *ext2_mount(struct file_system_type *fs_type,
  	int flags, const char *dev_name, void *data)

  {

  	return mount_bdev(fs_type, flags, dev_name, data, ext2_fill_super);

  }
  
  #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 no one 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;

  		tmp_bh.b_size = sb->s_blocksize;

  		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) {
  		mutex_unlock(&inode->i_mutex);

  		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",

  	.mount		= ext2_mount,

  	.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_AUTHOR("Remy Card and others");
  MODULE_DESCRIPTION("Second Extended Filesystem");
  MODULE_LICENSE("GPL");

  module_init(init_ext2_fs)
  module_exit(exit_ext2_fs)