/*
       *  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/config.h>
      #include <linux/module.h>
      #include <linux/string.h>
      #include <linux/fs.h>
      #include <linux/ext2_fs.h>
      #include <linux/slab.h>
      #include <linux/init.h>
      #include <linux/locks.h>
      #include <asm/uaccess.h>
      
      
      
      static char error_buf[1024];
      
      void ext2_error (struct super_block * sb, const char * function,
      		 const char * fmt, ...)
      {
      	va_list args;
      
      	if (!(sb->s_flags & MS_RDONLY)) {
      		sb->u.ext2_sb.s_mount_state |= EXT2_ERROR_FS;
      		sb->u.ext2_sb.s_es->s_state =
      			cpu_to_le16(le16_to_cpu(sb->u.ext2_sb.s_es->s_state) | EXT2_ERROR_FS);
      		mark_buffer_dirty(sb->u.ext2_sb.s_sbh);
      		sb->s_dirt = 1;
      	}
      	va_start (args, fmt);
      	vsprintf (error_buf, fmt, args);
      	va_end (args);
      	if (test_opt (sb, ERRORS_PANIC) ||
      	    (le16_to_cpu(sb->u.ext2_sb.s_es->s_errors) == EXT2_ERRORS_PANIC &&
      	     !test_opt (sb, ERRORS_CONT) && !test_opt (sb, ERRORS_RO)))
      		panic ("EXT2-fs panic (device %s): %s: %s\n",
      		       bdevname(sb->s_dev), function, error_buf);
      	printk (KERN_CRIT "EXT2-fs error (device %s): %s: %s\n",
      		bdevname(sb->s_dev), function, error_buf);
      	if (test_opt (sb, ERRORS_RO) ||
      	    (le16_to_cpu(sb->u.ext2_sb.s_es->s_errors) == EXT2_ERRORS_RO &&
      	     !test_opt (sb, ERRORS_CONT) && !test_opt (sb, ERRORS_PANIC))) {
      		printk ("Remounting filesystem read-only\n");
      		sb->s_flags |= MS_RDONLY;
      	}
      }
      
      NORET_TYPE void ext2_panic (struct super_block * sb, const char * function,
      			    const char * fmt, ...)
      {
      	va_list args;
      
      	if (!(sb->s_flags & MS_RDONLY)) {
      		sb->u.ext2_sb.s_mount_state |= EXT2_ERROR_FS;
      		sb->u.ext2_sb.s_es->s_state =
      			cpu_to_le16(le16_to_cpu(sb->u.ext2_sb.s_es->s_state) | EXT2_ERROR_FS);
      		mark_buffer_dirty(sb->u.ext2_sb.s_sbh);
      		sb->s_dirt = 1;
      	}
      	va_start (args, fmt);
      	vsprintf (error_buf, fmt, args);
      	va_end (args);
      	/* this is to prevent panic from syncing this filesystem */
      	if (sb->s_lock)
      		sb->s_lock=0;
      	sb->s_flags |= MS_RDONLY;
  82  	panic ("EXT2-fs panic (device %s): %s: %s\n",
      	       bdevname(sb->s_dev), function, error_buf);
  84  }
      
      void ext2_warning (struct super_block * sb, const char * function,
      		   const char * fmt, ...)
  88  {
      	va_list args;
  90  
      	va_start (args, fmt);
      	vsprintf (error_buf, fmt, args);
      	va_end (args);
  94  	printk (KERN_WARNING "EXT2-fs warning (device %s): %s: %s\n",
      		bdevname(sb->s_dev), function, error_buf);
      }
  97  
  98  void ext2_update_dynamic_rev(struct super_block *sb)
  99  {
 100  	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 */
      
 116  	/*
      	 * 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.
      	 */
 121  }
 122  
 123  void ext2_put_super (struct super_block * sb)
 124  {
      	int db_count;
      	int i;
 127  
      	if (!(sb->s_flags & MS_RDONLY)) {
 129  		sb->u.ext2_sb.s_es->s_state = le16_to_cpu(sb->u.ext2_sb.s_mount_state);
      		mark_buffer_dirty(sb->u.ext2_sb.s_sbh);
 131  	}
 132  	db_count = EXT2_SB(sb)->s_gdb_count;
      	for (i = 0; i < db_count; i++)
      		if (sb->u.ext2_sb.s_group_desc[i])
      			brelse (sb->u.ext2_sb.s_group_desc[i]);
      	kfree(sb->u.ext2_sb.s_group_desc);
      	for (i = 0; i < EXT2_MAX_GROUP_LOADED; i++)
      		if (sb->u.ext2_sb.s_inode_bitmap[i])
      			brelse (sb->u.ext2_sb.s_inode_bitmap[i]);
      	for (i = 0; i < EXT2_MAX_GROUP_LOADED; i++)
      		if (sb->u.ext2_sb.s_block_bitmap[i])
      			brelse (sb->u.ext2_sb.s_block_bitmap[i]);
      	brelse (sb->u.ext2_sb.s_sbh);
      
      	return;
      }
 147  
      static struct super_operations ext2_sops = {
      	read_inode:	ext2_read_inode,
      	write_inode:	ext2_write_inode,
      	put_inode:	ext2_put_inode,
      	delete_inode:	ext2_delete_inode,
 153  	put_super:	ext2_put_super,
 154  	write_super:	ext2_write_super,
      	statfs:		ext2_statfs,
      	remount_fs:	ext2_remount,
 157  };
 158  
      /*
       * This function has been shamelessly adapted from the msdos fs
       */
 162  static int parse_options (char * options, unsigned long * sb_block,
 163  			  unsigned short *resuid, unsigned short * resgid,
      			  unsigned long * mount_options)
      {
 166  	char * this_char;
      	char * value;
      
      	if (!options)
      		return 1;
      	for (this_char = strtok (options, ",");
      	     this_char != NULL;
      	     this_char = strtok (NULL, ",")) {
 174  		if ((value = strchr (this_char, '=')) != NULL)
 175  			*value++ = 0;
      		if (!strcmp (this_char, "bsddf"))
      			clear_opt (*mount_options, MINIX_DF);
      		else if (!strcmp (this_char, "nouid32")) {
 179  			set_opt (*mount_options, NO_UID32);
 180  		}
      		else if (!strcmp (this_char, "check")) {
 182  			if (!value || !*value || !strcmp (value, "none"))
      				clear_opt (*mount_options, CHECK);
      			else
 185  #ifdef CONFIG_EXT2_CHECK
      				set_opt (*mount_options, CHECK);
 187  #else
      				printk("EXT2 Check option not supported\n");
      #endif
 190  		}
      		else if (!strcmp (this_char, "debug"))
      			set_opt (*mount_options, DEBUG);
      		else if (!strcmp (this_char, "errors")) {
      			if (!value || !*value) {
      				printk ("EXT2-fs: the errors option requires "
 196  					"an argument\n");
 197  				return 0;
 198  			}
 199  			if (!strcmp (value, "continue")) {
 200  				clear_opt (*mount_options, ERRORS_RO);
 201  				clear_opt (*mount_options, ERRORS_PANIC);
      				set_opt (*mount_options, ERRORS_CONT);
      			}
      			else if (!strcmp (value, "remount-ro")) {
      				clear_opt (*mount_options, ERRORS_CONT);
      				clear_opt (*mount_options, ERRORS_PANIC);
 207  				set_opt (*mount_options, ERRORS_RO);
      			}
      			else if (!strcmp (value, "panic")) {
 210  				clear_opt (*mount_options, ERRORS_CONT);
      				clear_opt (*mount_options, ERRORS_RO);
      				set_opt (*mount_options, ERRORS_PANIC);
      			}
      			else {
      				printk ("EXT2-fs: Invalid errors option: %s\n",
 216  					value);
      				return 0;
 218  			}
 219  		}
      		else if (!strcmp (this_char, "grpid") ||
      			 !strcmp (this_char, "bsdgroups"))
      			set_opt (*mount_options, GRPID);
      		else if (!strcmp (this_char, "minixdf"))
      			set_opt (*mount_options, MINIX_DF);
 225  		else if (!strcmp (this_char, "nocheck"))
      			clear_opt (*mount_options, CHECK);
      		else if (!strcmp (this_char, "nogrpid") ||
      			 !strcmp (this_char, "sysvgroups"))
 229  			clear_opt (*mount_options, GRPID);
 230  		else if (!strcmp (this_char, "resgid")) {
      			if (!value || !*value) {
 232  				printk ("EXT2-fs: the resgid option requires "
      					"an argument\n");
 234  				return 0;
      			}
 236  			*resgid = simple_strtoul (value, &value, 0);
      			if (*value) {
 238  				printk ("EXT2-fs: Invalid resgid option: %s\n",
      					value);
 240  				return 0;
      			}
 242  		}
      		else if (!strcmp (this_char, "resuid")) {
      			if (!value || !*value) {
 245  				printk ("EXT2-fs: the resuid option requires "
      					"an argument");
      				return 0;
      			}
      			*resuid = simple_strtoul (value, &value, 0);
      			if (*value) {
      				printk ("EXT2-fs: Invalid resuid option: %s\n",
 252  					value);
      				return 0;
      			}
      		}
      		else if (!strcmp (this_char, "sb")) {
      			if (!value || !*value) {
 258  				printk ("EXT2-fs: the sb option requires "
 259  					"an argument");
      				return 0;
      			}
 262  			*sb_block = simple_strtoul (value, &value, 0);
      			if (*value) {
      				printk ("EXT2-fs: Invalid sb option: %s\n",
      					value);
      				return 0;
      			}
 268  		}
      		/* Silently ignore the quota options */
 270  		else if (!strcmp (this_char, "grpquota")
 271  		         || !strcmp (this_char, "noquota")
      		         || !strcmp (this_char, "quota")
      		         || !strcmp (this_char, "usrquota"))
 274  			/* Don't do anything ;-) */ ;
      		else {
 276  			printk ("EXT2-fs: Unrecognized mount option %s\n", this_char);
      			return 0;
 278  		}
      	}
      	return 1;
      }
      
      static int ext2_setup_super (struct super_block * sb,
      			      struct ext2_super_block * es,
      			      int read_only)
      {
      	int res = 0;
      	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 (!(sb->u.ext2_sb.s_mount_state & EXT2_VALID_FS))
      		printk ("EXT2-fs warning: mounting unchecked fs, "
      			"running e2fsck is recommended\n");
      	else if ((sb->u.ext2_sb.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");
 306  	else if (le32_to_cpu(es->s_checkinterval) &&
      		(le32_to_cpu(es->s_lastcheck) + le32_to_cpu(es->s_checkinterval) <= CURRENT_TIME))
      		printk ("EXT2-fs warning: checktime reached, "
      			"running e2fsck is recommended\n");
      	es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) & ~EXT2_VALID_FS);
      	if (!(__s16) le16_to_cpu(es->s_max_mnt_count))
      		es->s_max_mnt_count = (__s16) cpu_to_le16(EXT2_DFL_MAX_MNT_COUNT);
      	es->s_mnt_count=cpu_to_le16(le16_to_cpu(es->s_mnt_count) + 1);
      	es->s_mtime = cpu_to_le32(CURRENT_TIME);
 315  	mark_buffer_dirty(sb->u.ext2_sb.s_sbh);
 316  	sb->s_dirt = 1;
      	if (test_opt (sb, DEBUG))
      		printk ("[EXT II FS %s, %s, bs=%lu, fs=%lu, gc=%lu, "
 319  			"bpg=%lu, ipg=%lu, mo=%04lx]\n",
      			EXT2FS_VERSION, EXT2FS_DATE, sb->s_blocksize,
      			sb->u.ext2_sb.s_frag_size,
      			sb->u.ext2_sb.s_groups_count,
 323  			EXT2_BLOCKS_PER_GROUP(sb),
      			EXT2_INODES_PER_GROUP(sb),
 325  			sb->u.ext2_sb.s_mount_opt);
      #ifdef CONFIG_EXT2_CHECK
      	if (test_opt (sb, CHECK)) {
      		ext2_check_blocks_bitmap (sb);
      		ext2_check_inodes_bitmap (sb);
      	}
      #endif
      	return res;
      }
      
 335  static int ext2_check_descriptors (struct super_block * sb)
 336  {
      	int i;
      	int desc_block = 0;
      	unsigned long block = le32_to_cpu(sb->u.ext2_sb.s_es->s_first_data_block);
      	struct ext2_group_desc * gdp = NULL;
 341  
      	ext2_debug ("Checking group descriptors");
      
 344  	for (i = 0; i < sb->u.ext2_sb.s_groups_count; i++)
 345  	{
 346  		if ((i % EXT2_DESC_PER_BLOCK(sb)) == 0)
      			gdp = (struct ext2_group_desc *) sb->u.ext2_sb.s_group_desc[desc_block++]->b_data;
 348  		if (le32_to_cpu(gdp->bg_block_bitmap) < block ||
      		    le32_to_cpu(gdp->bg_block_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
      		{
 351  			ext2_error (sb, "ext2_check_descriptors",
      				    "Block bitmap for group %d"
 353  				    " not in group (block %lu)!",
      				    i, (unsigned long) le32_to_cpu(gdp->bg_block_bitmap));
 355  			return 0;
 356  		}
      		if (le32_to_cpu(gdp->bg_inode_bitmap) < block ||
      		    le32_to_cpu(gdp->bg_inode_bitmap) >= block + EXT2_BLOCKS_PER_GROUP(sb))
 359  		{
      			ext2_error (sb, "ext2_check_descriptors",
      				    "Inode bitmap for group %d"
 362  				    " 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) < block ||
      		    le32_to_cpu(gdp->bg_inode_table) + sb->u.ext2_sb.s_itb_per_group >=
      		    block + EXT2_BLOCKS_PER_GROUP(sb))
      		{
      			ext2_error (sb, "ext2_check_descriptors",
 371  				    "Inode table for group %d"
      				    " not in group (block %lu)!",
 373  				    i, (unsigned long) le32_to_cpu(gdp->bg_inode_table));
      			return 0;
      		}
      		block += EXT2_BLOCKS_PER_GROUP(sb);
      		gdp++;
      	}
      	return 1;
      }
      
 382  #define log2(n) ffz(~(n))
 383  
      struct super_block * ext2_read_super (struct super_block * sb, void * data,
      				      int silent)
      {
      	struct buffer_head * bh;
      	struct ext2_super_block * es;
      	unsigned long sb_block = 1;
      	unsigned short resuid = EXT2_DEF_RESUID;
      	unsigned short resgid = EXT2_DEF_RESGID;
      	unsigned long logic_sb_block = 1;
 393  	unsigned long offset = 0;
      	kdev_t dev = sb->s_dev;
      	int blocksize = BLOCK_SIZE;
 396  	int hblock;
 397  	int db_count;
 398  	int i, j;
      
 400  	/*
      	 * 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.
 404  	 * This is important for devices that have a hardware
      	 * sectorsize that is larger than the default.
      	 */
      	blocksize = get_hardblocksize(dev);
      	if( blocksize == 0 || blocksize < BLOCK_SIZE )
      	  {
      	    blocksize = BLOCK_SIZE;
 411  	  }
      
      	sb->u.ext2_sb.s_mount_opt = 0;
      	if (!parse_options ((char *) data, &sb_block, &resuid, &resgid,
      	    &sb->u.ext2_sb.s_mount_opt)) {
      		return NULL;
      	}
 418  
      	set_blocksize (dev, blocksize);
 420  
      	/*
      	 * If the superblock doesn't start on a sector boundary,
      	 * calculate the offset.  FIXME(eric) this doesn't make sense
      	 * that we would have to do this.
 425  	 */
      	if (blocksize != BLOCK_SIZE) {
      		logic_sb_block = (sb_block*BLOCK_SIZE) / blocksize;
      		offset = (sb_block*BLOCK_SIZE) % blocksize;
      	}
      
      	if (!(bh = bread (dev, logic_sb_block, blocksize))) {
      		printk ("EXT2-fs: unable to read superblock\n");
      		return NULL;
      	}
 435  	/*
      	 * Note: s_es must be initialized s_es as soon as possible because
      	 * some ext2 macro-instructions depend on its value
      	 */
      	es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
 440  	sb->u.ext2_sb.s_es = es;
 441  	sb->s_magic = le16_to_cpu(es->s_magic);
 442  	if (sb->s_magic != EXT2_SUPER_MAGIC) {
      		if (!silent)
      			printk ("VFS: Can't find an ext2 filesystem on dev "
      				"%s.\n", bdevname(dev));
      	failed_mount:
 447  		if (bh)
      			brelse(bh);
      		return NULL;
      	}
      	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) ||
 454  	     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.
      	 */
      	if ((i = EXT2_HAS_INCOMPAT_FEATURE(sb, ~EXT2_FEATURE_INCOMPAT_SUPP))) {
      		printk("EXT2-fs: %s: couldn't mount because of "
      		       "unsupported optional features (%x).\n",
      		       bdevname(dev), i);
      		goto failed_mount;
      	}
      	if (!(sb->s_flags & MS_RDONLY) &&
      	    (i = 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",
      		       bdevname(dev), i);
      		goto failed_mount;
      	}
      	sb->s_blocksize_bits =
      		le32_to_cpu(EXT2_SB(sb)->s_es->s_log_block_size) + 10;
      	sb->s_blocksize = 1 << sb->s_blocksize_bits;
      	if (sb->s_blocksize != BLOCK_SIZE &&
      	    (sb->s_blocksize == 1024 || sb->s_blocksize == 2048 ||
      	     sb->s_blocksize == 4096)) {
      		/*
      		 * Make sure the blocksize for the filesystem is larger
      		 * than the hardware sectorsize for the machine.
      		 */
      		hblock = get_hardblocksize(dev);
      		if(    (hblock != 0)
      		    && (sb->s_blocksize < hblock) )
      		{
      			printk("EXT2-fs: blocksize too small for device.\n");
 490  			goto failed_mount;
      		}
      
      		brelse (bh);
      		set_blocksize (dev, sb->s_blocksize);
      		logic_sb_block = (sb_block*BLOCK_SIZE) / sb->s_blocksize;
      		offset = (sb_block*BLOCK_SIZE) % sb->s_blocksize;
      		bh = bread (dev, logic_sb_block, sb->s_blocksize);
      		if(!bh) {
 499  			printk("EXT2-fs: Couldn't read superblock on "
      			       "2nd try.\n");
      			goto failed_mount;
      		}
      		es = (struct ext2_super_block *) (((char *)bh->b_data) + offset);
      		sb->u.ext2_sb.s_es = es;
 505  		if (es->s_magic != le16_to_cpu(EXT2_SUPER_MAGIC)) {
      			printk ("EXT2-fs: Magic mismatch, very weird !\n");
 507  			goto failed_mount;
 508  		}
      	}
 510  	if (le32_to_cpu(es->s_rev_level) == EXT2_GOOD_OLD_REV) {
 511  		sb->u.ext2_sb.s_inode_size = EXT2_GOOD_OLD_INODE_SIZE;
      		sb->u.ext2_sb.s_first_ino = EXT2_GOOD_OLD_FIRST_INO;
      	} else {
      		sb->u.ext2_sb.s_inode_size = le16_to_cpu(es->s_inode_size);
      		sb->u.ext2_sb.s_first_ino = le32_to_cpu(es->s_first_ino);
      		if (sb->u.ext2_sb.s_inode_size != EXT2_GOOD_OLD_INODE_SIZE) {
      			printk ("EXT2-fs: unsupported inode size: %d\n",
      				sb->u.ext2_sb.s_inode_size);
 519  			goto failed_mount;
 520  		}
      	}
      	sb->u.ext2_sb.s_frag_size = EXT2_MIN_FRAG_SIZE <<
 523  				   le32_to_cpu(es->s_log_frag_size);
      	if (sb->u.ext2_sb.s_frag_size)
      		sb->u.ext2_sb.s_frags_per_block = sb->s_blocksize /
      						  sb->u.ext2_sb.s_frag_size;
      	else
      		sb->s_magic = 0;
      	sb->u.ext2_sb.s_blocks_per_group = le32_to_cpu(es->s_blocks_per_group);
      	sb->u.ext2_sb.s_frags_per_group = le32_to_cpu(es->s_frags_per_group);
      	sb->u.ext2_sb.s_inodes_per_group = le32_to_cpu(es->s_inodes_per_group);
      	sb->u.ext2_sb.s_inodes_per_block = sb->s_blocksize /
      					   EXT2_INODE_SIZE(sb);
      	sb->u.ext2_sb.s_itb_per_group = sb->u.ext2_sb.s_inodes_per_group /
      				        sb->u.ext2_sb.s_inodes_per_block;
      	sb->u.ext2_sb.s_desc_per_block = sb->s_blocksize /
      					 sizeof (struct ext2_group_desc);
      	sb->u.ext2_sb.s_sbh = bh;
      	if (resuid != EXT2_DEF_RESUID)
 540  		sb->u.ext2_sb.s_resuid = resuid;
      	else
      		sb->u.ext2_sb.s_resuid = le16_to_cpu(es->s_def_resuid);
      	if (resgid != EXT2_DEF_RESGID)
 544  		sb->u.ext2_sb.s_resgid = resgid;
      	else
      		sb->u.ext2_sb.s_resgid = le16_to_cpu(es->s_def_resgid);
      	sb->u.ext2_sb.s_mount_state = le16_to_cpu(es->s_state);
 548  	sb->u.ext2_sb.s_addr_per_block_bits =
      		log2 (EXT2_ADDR_PER_BLOCK(sb));
      	sb->u.ext2_sb.s_desc_per_block_bits =
      		log2 (EXT2_DESC_PER_BLOCK(sb));
 552  	if (sb->s_magic != EXT2_SUPER_MAGIC) {
      		if (!silent)
      			printk ("VFS: Can't find an ext2 filesystem on dev "
      				"%s.\n",
 556  				bdevname(dev));
      		goto failed_mount;
 558  	}
      	if (sb->s_blocksize != bh->b_size) {
 560  		if (!silent)
      			printk ("VFS: Unsupported blocksize on dev "
      				"%s.\n", bdevname(dev));
      		goto failed_mount;
      	}
      
      	if (sb->s_blocksize != sb->u.ext2_sb.s_frag_size) {
      		printk ("EXT2-fs: fragsize %lu != blocksize %lu (not supported yet)\n",
 568  			sb->u.ext2_sb.s_frag_size, sb->s_blocksize);
      		goto failed_mount;
      	}
 571  
      	if (sb->u.ext2_sb.s_blocks_per_group > sb->s_blocksize * 8) {
      		printk ("EXT2-fs: #blocks per group too big: %lu\n",
      			sb->u.ext2_sb.s_blocks_per_group);
      		goto failed_mount;
      	}
 577  	if (sb->u.ext2_sb.s_frags_per_group > sb->s_blocksize * 8) {
      		printk ("EXT2-fs: #fragments per group too big: %lu\n",
      			sb->u.ext2_sb.s_frags_per_group);
      		goto failed_mount;
      	}
      	if (sb->u.ext2_sb.s_inodes_per_group > sb->s_blocksize * 8) {
      		printk ("EXT2-fs: #inodes per group too big: %lu\n",
      			sb->u.ext2_sb.s_inodes_per_group);
      		goto failed_mount;
      	}
      
      	sb->u.ext2_sb.s_groups_count = (le32_to_cpu(es->s_blocks_count) -
      				        le32_to_cpu(es->s_first_data_block) +
 590  				       EXT2_BLOCKS_PER_GROUP(sb) - 1) /
      				       EXT2_BLOCKS_PER_GROUP(sb);
      	db_count = (sb->u.ext2_sb.s_groups_count + EXT2_DESC_PER_BLOCK(sb) - 1) /
      		   EXT2_DESC_PER_BLOCK(sb);
      	sb->u.ext2_sb.s_group_desc = kmalloc (db_count * sizeof (struct buffer_head *), GFP_KERNEL);
      	if (sb->u.ext2_sb.s_group_desc == NULL) {
 596  		printk ("EXT2-fs: not enough memory\n");
 597  		goto failed_mount;
      	}
 599  	for (i = 0; i < db_count; i++) {
      		sb->u.ext2_sb.s_group_desc[i] = bread (dev, logic_sb_block + i + 1,
      						       sb->s_blocksize);
      		if (!sb->u.ext2_sb.s_group_desc[i]) {
      			for (j = 0; j < i; j++)
      				brelse (sb->u.ext2_sb.s_group_desc[j]);
      			kfree(sb->u.ext2_sb.s_group_desc);
      			printk ("EXT2-fs: unable to read group descriptors\n");
      			goto failed_mount;
      		}
      	}
 610  	if (!ext2_check_descriptors (sb)) {
      		for (j = 0; j < db_count; j++)
      			brelse (sb->u.ext2_sb.s_group_desc[j]);
      		kfree(sb->u.ext2_sb.s_group_desc);
      		printk ("EXT2-fs: group descriptors corrupted !\n");
 615  		goto failed_mount;
      	}
      	for (i = 0; i < EXT2_MAX_GROUP_LOADED; i++) {
      		sb->u.ext2_sb.s_inode_bitmap_number[i] = 0;
      		sb->u.ext2_sb.s_inode_bitmap[i] = NULL;
      		sb->u.ext2_sb.s_block_bitmap_number[i] = 0;
      		sb->u.ext2_sb.s_block_bitmap[i] = NULL;
      	}
      	sb->u.ext2_sb.s_loaded_inode_bitmaps = 0;
      	sb->u.ext2_sb.s_loaded_block_bitmaps = 0;
      	sb->u.ext2_sb.s_gdb_count = db_count;
      	/*
      	 * set up enough so that it can read an inode
      	 */
      	sb->s_op = &ext2_sops;
      	sb->s_root = d_alloc_root(iget(sb, EXT2_ROOT_INO));
      	if (!sb->s_root) {
      		for (i = 0; i < db_count; i++)
      			if (sb->u.ext2_sb.s_group_desc[i])
      				brelse (sb->u.ext2_sb.s_group_desc[i]);
      		kfree(sb->u.ext2_sb.s_group_desc);
      		brelse (bh);
      		printk ("EXT2-fs: get root inode failed\n");
      		return NULL;
 639  	}
      	ext2_setup_super (sb, es, sb->s_flags & MS_RDONLY);
      	return sb;
      }
 643  
 644  static void ext2_commit_super (struct super_block * sb,
      			       struct ext2_super_block * es)
      {
 647  	es->s_wtime = cpu_to_le32(CURRENT_TIME);
 648  	mark_buffer_dirty(sb->u.ext2_sb.s_sbh);
      	sb->s_dirt = 0;
 650  }
 651  
 652  /*
 653   * In the second extended file system, it is not necessary to
       * write the super block since we use a mapping of the
 655   * disk super block in a buffer.
       *
       * However, this function is still used to set the fs valid
 658   * 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)
      {
 665  	struct ext2_super_block * es;
      
 667  	if (!(sb->s_flags & MS_RDONLY)) {
 668  		es = sb->u.ext2_sb.s_es;
 669  
      		ext2_debug ("setting valid to 0\n");
 671  
 672  		if (le16_to_cpu(es->s_state) & EXT2_VALID_FS) {
      			es->s_state = cpu_to_le16(le16_to_cpu(es->s_state) & ~EXT2_VALID_FS);
      			es->s_mtime = cpu_to_le32(CURRENT_TIME);
      		}
      		ext2_commit_super (sb, es);
      	}
      	sb->s_dirt = 0;
      }
 680  
      int ext2_remount (struct super_block * sb, int * flags, char * data)
      {
      	struct ext2_super_block * es;
      	unsigned short resuid = sb->u.ext2_sb.s_resuid;
      	unsigned short resgid = sb->u.ext2_sb.s_resgid;
      	unsigned long new_mount_opt;
      	unsigned long tmp;
      
      	/*
      	 * Allow the "check" option to be passed as a remount option.
      	 */
 692  	new_mount_opt = sb->u.ext2_sb.s_mount_opt;
      	if (!parse_options (data, &tmp, &resuid, &resgid,
      			    &new_mount_opt))
      		return -EINVAL;
      
 697  	sb->u.ext2_sb.s_mount_opt = new_mount_opt;
      	sb->u.ext2_sb.s_resuid = resuid;
      	sb->u.ext2_sb.s_resgid = resgid;
      	es = sb->u.ext2_sb.s_es;
      	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 ||
      		    !(sb->u.ext2_sb.s_mount_state & EXT2_VALID_FS))
 706  			return 0;
 707  		/*
      		 * OK, we are remounting a valid rw partition rdonly, so set
 709  		 * the rdonly flag and then mark the partition as valid again.
      		 */
      		es->s_state = cpu_to_le16(sb->u.ext2_sb.s_mount_state);
 712  		es->s_mtime = cpu_to_le32(CURRENT_TIME);
      		mark_buffer_dirty(sb->u.ext2_sb.s_sbh);
      		sb->s_dirt = 1;
 715  		ext2_commit_super (sb, es);
 716  	}
      	else {
 718  		int ret;
      		if ((ret = EXT2_HAS_RO_COMPAT_FEATURE(sb,
      					       ~EXT2_FEATURE_RO_COMPAT_SUPP))) {
 721  			printk("EXT2-fs: %s: couldn't remount RDWR because of "
      			       "unsupported optional features (%x).\n",
      			       bdevname(sb->s_dev), ret);
      			return -EROFS;
      		}
      		/*
 727  		 * Mounting a RDONLY partition read-write, so reread and
 728  		 * store the current valid flag.  (It may have been changed
      		 * by e2fsck since we originally mounted the partition.)
      		 */
      		sb->u.ext2_sb.s_mount_state = le16_to_cpu(es->s_state);
      		if (!ext2_setup_super (sb, es, 0))
      			sb->s_flags &= ~MS_RDONLY;
      	}
      	return 0;
      }
      
      int ext2_statfs (struct super_block * sb, struct statfs * buf)
      {
 740  	unsigned long overhead;
 741  	int i;
      
      	if (test_opt (sb, MINIX_DF))
 744  		overhead = 0;
      	else {
      		/*
 747  		 * Compute the overhead (FS structures)
      		 */
      
      		/*
      		 * All of the blocks before first_data_block are
      		 * overhead
      		 */
 754  		overhead = le32_to_cpu(sb->u.ext2_sb.s_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 < EXT2_SB(sb)->s_groups_count; i++)
      			overhead += ext2_bg_has_super(sb, i) +
      				ext2_bg_num_gdb(sb, i);
 764  
      		/*
      		 * Every block group has an inode bitmap, a block
      		 * bitmap, and an inode table.
 768  		 */
 769  		overhead += (sb->u.ext2_sb.s_groups_count *
 770  			     (2 + sb->u.ext2_sb.s_itb_per_group));
      	}
 772  
      	buf->f_type = EXT2_SUPER_MAGIC;
      	buf->f_bsize = sb->s_blocksize;
 775  	buf->f_blocks = le32_to_cpu(sb->u.ext2_sb.s_es->s_blocks_count) - overhead;
      	buf->f_bfree = ext2_count_free_blocks (sb);
 777  	buf->f_bavail = buf->f_bfree - le32_to_cpu(sb->u.ext2_sb.s_es->s_r_blocks_count);
 778  	if (buf->f_bfree < le32_to_cpu(sb->u.ext2_sb.s_es->s_r_blocks_count))
 779  		buf->f_bavail = 0;
 780  	buf->f_files = le32_to_cpu(sb->u.ext2_sb.s_es->s_inodes_count);
      	buf->f_ffree = ext2_count_free_inodes (sb);
      	buf->f_namelen = EXT2_NAME_LEN;
      	return 0;
      }
 785  
      static DECLARE_FSTYPE_DEV(ext2_fs_type, "ext2", ext2_read_super);
      
      static int __init init_ext2_fs(void)
      {
              return register_filesystem(&ext2_fs_type);
      }
      
      static void __exit exit_ext2_fs(void)
      {
      	unregister_filesystem(&ext2_fs_type);
 796  }
 797  
 798  EXPORT_NO_SYMBOLS;
      
 800  module_init(init_ext2_fs)
 801  module_exit(exit_ext2_fs)