e2fsprogs/ext2fs/ext2_fs.h - codeaurora/busybox - Gitiles

 /*
  *  linux/include/linux/ext2_fs.h
  *
  * 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/include/linux/minix_fs.h
  *
  *  Copyright (C) 1991, 1992  Linus Torvalds
  */

 #ifndef _LINUX_EXT2_FS_H
 #define _LINUX_EXT2_FS_H

 #include "ext2_types.h"		/* Changed from linux/types.h */

 /*
  * The second extended filesystem constants/structures
  */

 /*
  * Define EXT2FS_DEBUG to produce debug messages
  */
 #undef EXT2FS_DEBUG

 /*
  * Define EXT2_PREALLOCATE to preallocate data blocks for expanding files
  */
 #define EXT2_PREALLOCATE
 #define EXT2_DEFAULT_PREALLOC_BLOCKS	8

 /*
  * The second extended file system version
  */
 #define EXT2FS_DATE		"95/08/09"
 #define EXT2FS_VERSION		"0.5b"

 /*
  * Special inode numbers
  */
 #define EXT2_BAD_INO		 1	/* Bad blocks inode */
 #define EXT2_ROOT_INO		 2	/* Root inode */
 #define EXT2_ACL_IDX_INO	 3	/* ACL inode */
 #define EXT2_ACL_DATA_INO	 4	/* ACL inode */
 #define EXT2_BOOT_LOADER_INO	 5	/* Boot loader inode */
 #define EXT2_UNDEL_DIR_INO	 6	/* Undelete directory inode */
 #define EXT2_RESIZE_INO		 7	/* Reserved group descriptors inode */
 #define EXT2_JOURNAL_INO	 8	/* Journal inode */

 /* First non-reserved inode for old ext2 filesystems */
 #define EXT2_GOOD_OLD_FIRST_INO	11

 /*
  * The second extended file system magic number
  */
 #define EXT2_SUPER_MAGIC	0xEF53

 #ifdef __KERNEL__
 #define EXT2_SB(sb)	(&((sb)->u.ext2_sb))
 #else
 /* Assume that user mode programs are passing in an ext2fs superblock, not
  * a kernel struct super_block.  This will allow us to call the feature-test
  * macros from user land. */
 #define EXT2_SB(sb)	(sb)
 #endif

 /*
  * Maximal count of links to a file
  */
 #define EXT2_LINK_MAX		32000

 /*
  * Macro-instructions used to manage several block sizes
  */
 #define EXT2_MIN_BLOCK_LOG_SIZE		10	/* 1024 */
 #define EXT2_MAX_BLOCK_LOG_SIZE		16	/* 65536 */
 #define EXT2_MIN_BLOCK_SIZE	(1 << EXT2_MIN_BLOCK_LOG_SIZE)
 #define EXT2_MAX_BLOCK_SIZE	(1 << EXT2_MAX_BLOCK_LOG_SIZE)
 #ifdef __KERNEL__
 #define EXT2_BLOCK_SIZE(s)	((s)->s_blocksize)
 #define EXT2_BLOCK_SIZE_BITS(s)	((s)->s_blocksize_bits)
 #define EXT2_ADDR_PER_BLOCK_BITS(s)	(EXT2_SB(s)->addr_per_block_bits)
 #define EXT2_INODE_SIZE(s)	(EXT2_SB(s)->s_inode_size)
 #define EXT2_FIRST_INO(s)	(EXT2_SB(s)->s_first_ino)
 #else
 #define EXT2_BLOCK_SIZE(s)	(EXT2_MIN_BLOCK_SIZE << (s)->s_log_block_size)
 #define EXT2_BLOCK_SIZE_BITS(s)	((s)->s_log_block_size + 10)
 #define EXT2_INODE_SIZE(s)	(((s)->s_rev_level == EXT2_GOOD_OLD_REV) ? \
 				 EXT2_GOOD_OLD_INODE_SIZE : (s)->s_inode_size)
 #define EXT2_FIRST_INO(s)	(((s)->s_rev_level == EXT2_GOOD_OLD_REV) ? \
 				 EXT2_GOOD_OLD_FIRST_INO : (s)->s_first_ino)
 #endif
 #define EXT2_ADDR_PER_BLOCK(s)	(EXT2_BLOCK_SIZE(s) / sizeof(__u32))

 /*
  * Macro-instructions used to manage fragments
  */
 #define EXT2_MIN_FRAG_SIZE		EXT2_MIN_BLOCK_SIZE
 #define EXT2_MAX_FRAG_SIZE		EXT2_MAX_BLOCK_SIZE
 #define EXT2_MIN_FRAG_LOG_SIZE		EXT2_MIN_BLOCK_LOG_SIZE
 #ifdef __KERNEL__
 # define EXT2_FRAG_SIZE(s)		(EXT2_SB(s)->s_frag_size)
 # define EXT2_FRAGS_PER_BLOCK(s)	(EXT2_SB(s)->s_frags_per_block)
 #else
 # define EXT2_FRAG_SIZE(s)		(EXT2_MIN_FRAG_SIZE << (s)->s_log_frag_size)
 # define EXT2_FRAGS_PER_BLOCK(s)	(EXT2_BLOCK_SIZE(s) / EXT2_FRAG_SIZE(s))
 #endif

 /*
  * ACL structures
  */
 struct ext2_acl_header	/* Header of Access Control Lists */
 {
 	__u32	aclh_size;
 	__u32	aclh_file_count;
 	__u32	aclh_acle_count;
 	__u32	aclh_first_acle;
 };

 struct ext2_acl_entry	/* Access Control List Entry */
 {
 	__u32	acle_size;
 	__u16	acle_perms;	/* Access permissions */
 	__u16	acle_type;	/* Type of entry */
 	__u16	acle_tag;	/* User or group identity */
 	__u16	acle_pad1;
 	__u32	acle_next;	/* Pointer on next entry for the */
 					/* same inode or on next free entry */
 };

 /*
  * Structure of a blocks group descriptor
  */
 struct ext2_group_desc
 {
 	__u32	bg_block_bitmap;		/* Blocks bitmap block */
 	__u32	bg_inode_bitmap;		/* Inodes bitmap block */
 	__u32	bg_inode_table;		/* Inodes table block */
 	__u16	bg_free_blocks_count;	/* Free blocks count */
 	__u16	bg_free_inodes_count;	/* Free inodes count */
 	__u16	bg_used_dirs_count;	/* Directories count */
 	__u16	bg_pad;
 	__u32	bg_reserved[3];
 };

 /*
  * Data structures used by the directory indexing feature
  *
  * Note: all of the multibyte integer fields are little endian.
  */

 /*
  * Note: dx_root_info is laid out so that if it should somehow get
  * overlaid by a dirent the two low bits of the hash version will be
  * zero.  Therefore, the hash version mod 4 should never be 0.
  * Sincerely, the paranoia department.
  */
 struct ext2_dx_root_info {
 	__u32 reserved_zero;
 	__u8 hash_version; /* 0 now, 1 at release */
 	__u8 info_length; /* 8 */
 	__u8 indirect_levels;
 	__u8 unused_flags;
 };

 #define EXT2_HASH_LEGACY	0
 #define EXT2_HASH_HALF_MD4	1
 #define EXT2_HASH_TEA		2

 #define EXT2_HASH_FLAG_INCOMPAT	0x1

 struct ext2_dx_entry {
 	__u32 hash;
 	__u32 block;
 };

 struct ext2_dx_countlimit {
 	__u16 limit;
 	__u16 count;
 };


 /*
  * Macro-instructions used to manage group descriptors
  */
 #define EXT2_BLOCKS_PER_GROUP(s)	(EXT2_SB(s)->s_blocks_per_group)
 #define EXT2_INODES_PER_GROUP(s)	(EXT2_SB(s)->s_inodes_per_group)
 #define EXT2_INODES_PER_BLOCK(s)	(EXT2_BLOCK_SIZE(s)/EXT2_INODE_SIZE(s))
 /* limits imposed by 16-bit value gd_free_{blocks,inode}_count */
 #define EXT2_MAX_BLOCKS_PER_GROUP(s)	((1 << 16) - 8)
 #define EXT2_MAX_INODES_PER_GROUP(s)	((1 << 16) - EXT2_INODES_PER_BLOCK(s))
 #ifdef __KERNEL__
 #define EXT2_DESC_PER_BLOCK(s)		(EXT2_SB(s)->s_desc_per_block)
 #define EXT2_DESC_PER_BLOCK_BITS(s)	(EXT2_SB(s)->s_desc_per_block_bits)
 #else
 #define EXT2_DESC_PER_BLOCK(s)		(EXT2_BLOCK_SIZE(s) / sizeof (struct ext2_group_desc))
 #endif

 /*
  * Constants relative to the data blocks
  */
 #define EXT2_NDIR_BLOCKS		12
 #define EXT2_IND_BLOCK			EXT2_NDIR_BLOCKS
 #define EXT2_DIND_BLOCK			(EXT2_IND_BLOCK + 1)
 #define EXT2_TIND_BLOCK			(EXT2_DIND_BLOCK + 1)
 #define EXT2_N_BLOCKS			(EXT2_TIND_BLOCK + 1)

 /*
  * Inode flags
  */
 #define EXT2_SECRM_FL			0x00000001 /* Secure deletion */
 #define EXT2_UNRM_FL			0x00000002 /* Undelete */
 #define EXT2_COMPR_FL			0x00000004 /* Compress file */
 #define EXT2_SYNC_FL			0x00000008 /* Synchronous updates */
 #define EXT2_IMMUTABLE_FL		0x00000010 /* Immutable file */
 #define EXT2_APPEND_FL			0x00000020 /* writes to file may only append */
 #define EXT2_NODUMP_FL			0x00000040 /* do not dump file */
 #define EXT2_NOATIME_FL			0x00000080 /* do not update atime */
 /* Reserved for compression usage... */
 #define EXT2_DIRTY_FL			0x00000100
 #define EXT2_COMPRBLK_FL		0x00000200 /* One or more compressed clusters */
 #define EXT2_NOCOMPR_FL			0x00000400 /* Access raw compressed data */
 #define EXT2_ECOMPR_FL			0x00000800 /* Compression error */
 /* End compression flags --- maybe not all used */
 #define EXT2_BTREE_FL			0x00001000 /* btree format dir */
 #define EXT2_INDEX_FL			0x00001000 /* hash-indexed directory */
 #define EXT2_IMAGIC_FL			0x00002000
 #define EXT3_JOURNAL_DATA_FL		0x00004000 /* file data should be journaled */
 #define EXT2_NOTAIL_FL			0x00008000 /* file tail should not be merged */
 #define EXT2_DIRSYNC_FL 		0x00010000 /* Synchronous directory modifications */
 #define EXT2_TOPDIR_FL			0x00020000 /* Top of directory hierarchies*/
 #define EXT3_EXTENTS_FL 		0x00080000 /* Inode uses extents */
 #define EXT2_RESERVED_FL		0x80000000 /* reserved for ext2 lib */

 #define EXT2_FL_USER_VISIBLE		0x0003DFFF /* User visible flags */
 #define EXT2_FL_USER_MODIFIABLE		0x000080FF /* User modifiable flags */

 /*
  * ioctl commands
  */
 #define EXT2_IOC_GETFLAGS		_IOR('f', 1, long)
 #define EXT2_IOC_SETFLAGS		_IOW('f', 2, long)
 #define EXT2_IOC_GETVERSION		_IOR('v', 1, long)
 #define EXT2_IOC_SETVERSION		_IOW('v', 2, long)

 /*
  * Structure of an inode on the disk
  */
 struct ext2_inode {
 	__u16	i_mode;		/* File mode */
 	__u16	i_uid;		/* Low 16 bits of Owner Uid */
 	__u32	i_size;		/* Size in bytes */
 	__u32	i_atime;	/* Access time */
 	__u32	i_ctime;	/* Creation time */
 	__u32	i_mtime;	/* Modification time */
 	__u32	i_dtime;	/* Deletion Time */
 	__u16	i_gid;		/* Low 16 bits of Group Id */
 	__u16	i_links_count;	/* Links count */
 	__u32	i_blocks;	/* Blocks count */
 	__u32	i_flags;	/* File flags */
 	union {
 		struct {
 			__u32  l_i_reserved1;
 		} linux1;
 		struct {
 			__u32  h_i_translator;
 		} hurd1;
 		struct {
 			__u32  m_i_reserved1;
 		} masix1;
 	} osd1;				/* OS dependent 1 */
 	__u32	i_block[EXT2_N_BLOCKS];/* Pointers to blocks */
 	__u32	i_generation;	/* File version (for NFS) */
 	__u32	i_file_acl;	/* File ACL */
 	__u32	i_dir_acl;	/* Directory ACL */
 	__u32	i_faddr;	/* Fragment address */
 	union {
 		struct {
 			__u8	l_i_frag;	/* Fragment number */
 			__u8	l_i_fsize;	/* Fragment size */
 			__u16	i_pad1;
 			__u16	l_i_uid_high;	/* these 2 fields    */
 			__u16	l_i_gid_high;	/* were reserved2[0] */
 			__u32	l_i_reserved2;
 		} linux2;
 		struct {
 			__u8	h_i_frag;	/* Fragment number */
 			__u8	h_i_fsize;	/* Fragment size */
 			__u16	h_i_mode_high;
 			__u16	h_i_uid_high;
 			__u16	h_i_gid_high;
 			__u32	h_i_author;
 		} hurd2;
 		struct {
 			__u8	m_i_frag;	/* Fragment number */
 			__u8	m_i_fsize;	/* Fragment size */
 			__u16	m_pad1;
 			__u32	m_i_reserved2[2];
 		} masix2;
 	} osd2;				/* OS dependent 2 */
 };

 /*
  * Permanent part of an large inode on the disk
  */
 struct ext2_inode_large {
 	__u16	i_mode;		/* File mode */
 	__u16	i_uid;		/* Low 16 bits of Owner Uid */
 	__u32	i_size;		/* Size in bytes */
 	__u32	i_atime;	/* Access time */
 	__u32	i_ctime;	/* Creation time */
 	__u32	i_mtime;	/* Modification time */
 	__u32	i_dtime;	/* Deletion Time */
 	__u16	i_gid;		/* Low 16 bits of Group Id */
 	__u16	i_links_count;	/* Links count */
 	__u32	i_blocks;	/* Blocks count */
 	__u32	i_flags;	/* File flags */
 	union {
 		struct {
 			__u32  l_i_reserved1;
 		} linux1;
 		struct {
 			__u32  h_i_translator;
 		} hurd1;
 		struct {
 			__u32  m_i_reserved1;
 		} masix1;
 	} osd1;				/* OS dependent 1 */
 	__u32	i_block[EXT2_N_BLOCKS];/* Pointers to blocks */
 	__u32	i_generation;	/* File version (for NFS) */
 	__u32	i_file_acl;	/* File ACL */
 	__u32	i_dir_acl;	/* Directory ACL */
 	__u32	i_faddr;	/* Fragment address */
 	union {
 		struct {
 			__u8	l_i_frag;	/* Fragment number */
 			__u8	l_i_fsize;	/* Fragment size */
 			__u16	i_pad1;
 			__u16	l_i_uid_high;	/* these 2 fields    */
 			__u16	l_i_gid_high;	/* were reserved2[0] */
 			__u32	l_i_reserved2;
 		} linux2;
 		struct {
 			__u8	h_i_frag;	/* Fragment number */
 			__u8	h_i_fsize;	/* Fragment size */
 			__u16	h_i_mode_high;
 			__u16	h_i_uid_high;
 			__u16	h_i_gid_high;
 			__u32	h_i_author;
 		} hurd2;
 		struct {
 			__u8	m_i_frag;	/* Fragment number */
 			__u8	m_i_fsize;	/* Fragment size */
 			__u16	m_pad1;
 			__u32	m_i_reserved2[2];
 		} masix2;
 	} osd2;				/* OS dependent 2 */
 	__u16	i_extra_isize;
 	__u16	i_pad1;
 };

 #define i_size_high	i_dir_acl

 #if defined(__KERNEL__) || defined(__linux__)
 #define i_reserved1	osd1.linux1.l_i_reserved1
 #define i_frag		osd2.linux2.l_i_frag
 #define i_fsize		osd2.linux2.l_i_fsize
 #define i_uid_low	i_uid
 #define i_gid_low	i_gid
 #define i_uid_high	osd2.linux2.l_i_uid_high
 #define i_gid_high	osd2.linux2.l_i_gid_high
 #define i_reserved2	osd2.linux2.l_i_reserved2

 #else
 #if defined(__GNU__)

 #define i_translator	osd1.hurd1.h_i_translator
 #define i_frag		osd2.hurd2.h_i_frag;
 #define i_fsize		osd2.hurd2.h_i_fsize;
 #define i_uid_high	osd2.hurd2.h_i_uid_high
 #define i_gid_high	osd2.hurd2.h_i_gid_high
 #define i_author	osd2.hurd2.h_i_author

 #else
 #if defined(__masix__)

 #define i_reserved1	osd1.masix1.m_i_reserved1
 #define i_frag		osd2.masix2.m_i_frag
 #define i_fsize		osd2.masix2.m_i_fsize
 #define i_reserved2	osd2.masix2.m_i_reserved2

 #endif  /* __masix__ */
 #endif  /* __GNU__ */
 #endif	/* defined(__KERNEL__) || defined(__linux__) */

 /*
  * File system states
  */
 #define EXT2_VALID_FS			0x0001	/* Unmounted cleanly */
 #define EXT2_ERROR_FS			0x0002	/* Errors detected */

 /*
  * Mount flags
  */
 #define EXT2_MOUNT_CHECK		0x0001	/* Do mount-time checks */
 #define EXT2_MOUNT_GRPID		0x0004	/* Create files with directory's group */
 #define EXT2_MOUNT_DEBUG		0x0008	/* Some debugging messages */
 #define EXT2_MOUNT_ERRORS_CONT		0x0010	/* Continue on errors */
 #define EXT2_MOUNT_ERRORS_RO		0x0020	/* Remount fs ro on errors */
 #define EXT2_MOUNT_ERRORS_PANIC		0x0040	/* Panic on errors */
 #define EXT2_MOUNT_MINIX_DF		0x0080	/* Mimics the Minix statfs */
 #define EXT2_MOUNT_NO_UID32		0x0200  /* Disable 32-bit UIDs */

 #define clear_opt(o, opt)		o &= ~EXT2_MOUNT_##opt
 #define set_opt(o, opt)			o |= EXT2_MOUNT_##opt
 #define test_opt(sb, opt)		(EXT2_SB(sb)->s_mount_opt & \
 					 EXT2_MOUNT_##opt)
 /*
  * Maximal mount counts between two filesystem checks
  */
 #define EXT2_DFL_MAX_MNT_COUNT		20	/* Allow 20 mounts */
 #define EXT2_DFL_CHECKINTERVAL		0	/* Don't use interval check */

 /*
  * Behaviour when detecting errors
  */
 #define EXT2_ERRORS_CONTINUE		1	/* Continue execution */
 #define EXT2_ERRORS_RO			2	/* Remount fs read-only */
 #define EXT2_ERRORS_PANIC		3	/* Panic */
 #define EXT2_ERRORS_DEFAULT		EXT2_ERRORS_CONTINUE

 /*
  * Structure of the super block
  */
 struct ext2_super_block {
 	__u32	s_inodes_count;		/* Inodes count */
 	__u32	s_blocks_count;		/* Blocks count */
 	__u32	s_r_blocks_count;	/* Reserved blocks count */
 	__u32	s_free_blocks_count;	/* Free blocks count */
 	__u32	s_free_inodes_count;	/* Free inodes count */
 	__u32	s_first_data_block;	/* First Data Block */
 	__u32	s_log_block_size;	/* Block size */
 	__s32	s_log_frag_size;	/* Fragment size */
 	__u32	s_blocks_per_group;	/* # Blocks per group */
 	__u32	s_frags_per_group;	/* # Fragments per group */
 	__u32	s_inodes_per_group;	/* # Inodes per group */
 	__u32	s_mtime;		/* Mount time */
 	__u32	s_wtime;		/* Write time */
 	__u16	s_mnt_count;		/* Mount count */
 	__s16	s_max_mnt_count;	/* Maximal mount count */
 	__u16	s_magic;		/* Magic signature */
 	__u16	s_state;		/* File system state */
 	__u16	s_errors;		/* Behaviour when detecting errors */
 	__u16	s_minor_rev_level;	/* minor revision level */
 	__u32	s_lastcheck;		/* time of last check */
 	__u32	s_checkinterval;	/* max. time between checks */
 	__u32	s_creator_os;		/* OS */
 	__u32	s_rev_level;		/* Revision level */
 	__u16	s_def_resuid;		/* Default uid for reserved blocks */
 	__u16	s_def_resgid;		/* Default gid for reserved blocks */
 	/*
 	 * These fields are for EXT2_DYNAMIC_REV superblocks only.
 	 *
 	 * Note: the difference between the compatible feature set and
 	 * the incompatible feature set is that if there is a bit set
 	 * in the incompatible feature set that the kernel doesn't
 	 * know about, it should refuse to mount the filesystem.
 	 *
 	 * e2fsck's requirements are more strict; if it doesn't know
 	 * about a feature in either the compatible or incompatible
 	 * feature set, it must abort and not try to meddle with
 	 * things it doesn't understand...
 	 */
 	__u32	s_first_ino;		/* First non-reserved inode */
 	__u16   s_inode_size;		/* size of inode structure */
 	__u16	s_block_group_nr;	/* block group # of this superblock */
 	__u32	s_feature_compat;	/* compatible feature set */
 	__u32	s_feature_incompat;	/* incompatible feature set */
 	__u32	s_feature_ro_compat;	/* readonly-compatible feature set */
 	__u8	s_uuid[16];		/* 128-bit uuid for volume */
 	char	s_volume_name[16];	/* volume name */
 	char	s_last_mounted[64];	/* directory where last mounted */
 	__u32	s_algorithm_usage_bitmap; /* For compression */
 	/*
 	 * Performance hints.  Directory preallocation should only
 	 * happen if the EXT2_FEATURE_COMPAT_DIR_PREALLOC flag is on.
 	 */
 	__u8	s_prealloc_blocks;	/* Nr of blocks to try to preallocate*/
 	__u8	s_prealloc_dir_blocks;	/* Nr to preallocate for dirs */
 	__u16	s_reserved_gdt_blocks;	/* Per group table for online growth */
 	/*
 	 * Journaling support valid if EXT2_FEATURE_COMPAT_HAS_JOURNAL set.
 	 */
 	__u8	s_journal_uuid[16];	/* uuid of journal superblock */
 	__u32	s_journal_inum;		/* inode number of journal file */
 	__u32	s_journal_dev;		/* device number of journal file */
 	__u32	s_last_orphan;		/* start of list of inodes to delete */
 	__u32	s_hash_seed[4];		/* HTREE hash seed */
 	__u8	s_def_hash_version;	/* Default hash version to use */
 	__u8	s_jnl_backup_type; 	/* Default type of journal backup */
 	__u16	s_reserved_word_pad;
 	__u32	s_default_mount_opts;
 	__u32	s_first_meta_bg;	/* First metablock group */
 	__u32	s_mkfs_time;		/* When the filesystem was created */
 	__u32	s_jnl_blocks[17]; 	/* Backup of the journal inode */
 	__u32	s_reserved[172];	/* Padding to the end of the block */
 };

 /*
  * Codes for operating systems
  */
 #define EXT2_OS_LINUX		0
 #define EXT2_OS_HURD		1
 #define EXT2_OS_MASIX		2
 #define EXT2_OS_FREEBSD		3
 #define EXT2_OS_LITES		4

 /*
  * Revision levels
  */
 #define EXT2_GOOD_OLD_REV	0	/* The good old (original) format */
 #define EXT2_DYNAMIC_REV	1	/* V2 format w/ dynamic inode sizes */

 #define EXT2_CURRENT_REV	EXT2_GOOD_OLD_REV
 #define EXT2_MAX_SUPP_REV	EXT2_DYNAMIC_REV

 #define EXT2_GOOD_OLD_INODE_SIZE 128

 /*
  * Journal inode backup types
  */
 #define EXT3_JNL_BACKUP_BLOCKS	1

 /*
  * Feature set definitions
  */

 #define EXT2_HAS_COMPAT_FEATURE(sb,mask)			\
 	( EXT2_SB(sb)->s_feature_compat & (mask) )
 #define EXT2_HAS_RO_COMPAT_FEATURE(sb,mask)			\
 	( EXT2_SB(sb)->s_feature_ro_compat & (mask) )
 #define EXT2_HAS_INCOMPAT_FEATURE(sb,mask)			\
 	( EXT2_SB(sb)->s_feature_incompat & (mask) )

 #define EXT2_FEATURE_COMPAT_DIR_PREALLOC	0x0001
 #define EXT2_FEATURE_COMPAT_IMAGIC_INODES	0x0002
 #define EXT3_FEATURE_COMPAT_HAS_JOURNAL		0x0004
 #define EXT2_FEATURE_COMPAT_EXT_ATTR		0x0008
 #define EXT2_FEATURE_COMPAT_RESIZE_INODE	0x0010
 #define EXT2_FEATURE_COMPAT_DIR_INDEX		0x0020

 #define EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER	0x0001
 #define EXT2_FEATURE_RO_COMPAT_LARGE_FILE	0x0002
 /* #define EXT2_FEATURE_RO_COMPAT_BTREE_DIR	0x0004 not used */

 #define EXT2_FEATURE_INCOMPAT_COMPRESSION	0x0001
 #define EXT2_FEATURE_INCOMPAT_FILETYPE		0x0002
 #define EXT3_FEATURE_INCOMPAT_RECOVER		0x0004 /* Needs recovery */
 #define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV	0x0008 /* Journal device */
 #define EXT2_FEATURE_INCOMPAT_META_BG		0x0010
 #define EXT3_FEATURE_INCOMPAT_EXTENTS		0x0040


 #define EXT2_FEATURE_COMPAT_SUPP	0
 #define EXT2_FEATURE_INCOMPAT_SUPP	(EXT2_FEATURE_INCOMPAT_FILETYPE)
 #define EXT2_FEATURE_RO_COMPAT_SUPP	(EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER| \
 					 EXT2_FEATURE_RO_COMPAT_LARGE_FILE| \
 					 EXT2_FEATURE_RO_COMPAT_BTREE_DIR)

 /*
  * Default values for user and/or group using reserved blocks
  */
 #define EXT2_DEF_RESUID		0
 #define EXT2_DEF_RESGID		0

 /*
  * Default mount options
  */
 #define EXT2_DEFM_DEBUG		0x0001
 #define EXT2_DEFM_BSDGROUPS	0x0002
 #define EXT2_DEFM_XATTR_USER	0x0004
 #define EXT2_DEFM_ACL		0x0008
 #define EXT2_DEFM_UID16		0x0010
 #define EXT3_DEFM_JMODE		0x0060
 #define EXT3_DEFM_JMODE_DATA	0x0020
 #define EXT3_DEFM_JMODE_ORDERED	0x0040
 #define EXT3_DEFM_JMODE_WBACK	0x0060

 /*
  * Structure of a directory entry
  */
 #define EXT2_NAME_LEN 255

 struct ext2_dir_entry {
 	__u32	inode;			/* Inode number */
 	__u16	rec_len;		/* Directory entry length */
 	__u16	name_len;		/* Name length */
 	char	name[EXT2_NAME_LEN];	/* File name */
 };

 /*
  * The new version of the directory entry.  Since EXT2 structures are
  * stored in intel byte order, and the name_len field could never be
  * bigger than 255 chars, it's safe to reclaim the extra byte for the
  * file_type field.
  */
 struct ext2_dir_entry_2 {
 	__u32	inode;			/* Inode number */
 	__u16	rec_len;		/* Directory entry length */
 	__u8	name_len;		/* Name length */
 	__u8	file_type;
 	char	name[EXT2_NAME_LEN];	/* File name */
 };

 /*
  * Ext2 directory file types.  Only the low 3 bits are used.  The
  * other bits are reserved for now.
  */
 #define EXT2_FT_UNKNOWN		0
 #define EXT2_FT_REG_FILE	1
 #define EXT2_FT_DIR		2
 #define EXT2_FT_CHRDEV		3
 #define EXT2_FT_BLKDEV		4
 #define EXT2_FT_FIFO		5
 #define EXT2_FT_SOCK		6
 #define EXT2_FT_SYMLINK		7

 #define EXT2_FT_MAX		8

 /*
  * EXT2_DIR_PAD defines the directory entries boundaries
  *
  * NOTE: It must be a multiple of 4
  */
 #define EXT2_DIR_PAD			4
 #define EXT2_DIR_ROUND			(EXT2_DIR_PAD - 1)
 #define EXT2_DIR_REC_LEN(name_len)	(((name_len) + 8 + EXT2_DIR_ROUND) & \
 					 ~EXT2_DIR_ROUND)

 #endif	/* _LINUX_EXT2_FS_H */
	/*
	* linux/include/linux/ext2_fs.h
	*
	* 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/include/linux/minix_fs.h
	*
	* Copyright (C) 1991, 1992 Linus Torvalds
	*/

	#ifndef _LINUX_EXT2_FS_H
	#define _LINUX_EXT2_FS_H

	#include "ext2_types.h" /* Changed from linux/types.h */

	/*
	* The second extended filesystem constants/structures
	*/

	/*
	* Define EXT2FS_DEBUG to produce debug messages
	*/
	#undef EXT2FS_DEBUG

	/*
	* Define EXT2_PREALLOCATE to preallocate data blocks for expanding files
	*/
	#define EXT2_PREALLOCATE
	#define EXT2_DEFAULT_PREALLOC_BLOCKS 8

	/*
	* The second extended file system version
	*/
	#define EXT2FS_DATE "95/08/09"
	#define EXT2FS_VERSION "0.5b"

	/*
	* Special inode numbers
	*/
	#define EXT2_BAD_INO 1 /* Bad blocks inode */
	#define EXT2_ROOT_INO 2 /* Root inode */
	#define EXT2_ACL_IDX_INO 3 /* ACL inode */
	#define EXT2_ACL_DATA_INO 4 /* ACL inode */
	#define EXT2_BOOT_LOADER_INO 5 /* Boot loader inode */
	#define EXT2_UNDEL_DIR_INO 6 /* Undelete directory inode */
	#define EXT2_RESIZE_INO 7 /* Reserved group descriptors inode */
	#define EXT2_JOURNAL_INO 8 /* Journal inode */

	/* First non-reserved inode for old ext2 filesystems */
	#define EXT2_GOOD_OLD_FIRST_INO 11

	/*
	* The second extended file system magic number
	*/
	#define EXT2_SUPER_MAGIC 0xEF53

	#ifdef __KERNEL__
	#define EXT2_SB(sb) (&((sb)->u.ext2_sb))
	#else
	/* Assume that user mode programs are passing in an ext2fs superblock, not
	* a kernel struct super_block. This will allow us to call the feature-test
	* macros from user land. */
	#define EXT2_SB(sb) (sb)
	#endif

	/*
	* Maximal count of links to a file
	*/
	#define EXT2_LINK_MAX 32000

	/*
	* Macro-instructions used to manage several block sizes
	*/
	#define EXT2_MIN_BLOCK_LOG_SIZE 10 /* 1024 */
	#define EXT2_MAX_BLOCK_LOG_SIZE 16 /* 65536 */
	#define EXT2_MIN_BLOCK_SIZE (1 << EXT2_MIN_BLOCK_LOG_SIZE)
	#define EXT2_MAX_BLOCK_SIZE (1 << EXT2_MAX_BLOCK_LOG_SIZE)
	#ifdef __KERNEL__
	#define EXT2_BLOCK_SIZE(s) ((s)->s_blocksize)
	#define EXT2_BLOCK_SIZE_BITS(s) ((s)->s_blocksize_bits)
	#define EXT2_ADDR_PER_BLOCK_BITS(s) (EXT2_SB(s)->addr_per_block_bits)
	#define EXT2_INODE_SIZE(s) (EXT2_SB(s)->s_inode_size)
	#define EXT2_FIRST_INO(s) (EXT2_SB(s)->s_first_ino)
	#else
	#define EXT2_BLOCK_SIZE(s) (EXT2_MIN_BLOCK_SIZE << (s)->s_log_block_size)
	#define EXT2_BLOCK_SIZE_BITS(s) ((s)->s_log_block_size + 10)
	#define EXT2_INODE_SIZE(s) (((s)->s_rev_level == EXT2_GOOD_OLD_REV) ? \
	EXT2_GOOD_OLD_INODE_SIZE : (s)->s_inode_size)
	#define EXT2_FIRST_INO(s) (((s)->s_rev_level == EXT2_GOOD_OLD_REV) ? \
	EXT2_GOOD_OLD_FIRST_INO : (s)->s_first_ino)
	#endif
	#define EXT2_ADDR_PER_BLOCK(s) (EXT2_BLOCK_SIZE(s) / sizeof(__u32))

	/*
	* Macro-instructions used to manage fragments
	*/
	#define EXT2_MIN_FRAG_SIZE EXT2_MIN_BLOCK_SIZE
	#define EXT2_MAX_FRAG_SIZE EXT2_MAX_BLOCK_SIZE
	#define EXT2_MIN_FRAG_LOG_SIZE EXT2_MIN_BLOCK_LOG_SIZE
	#ifdef __KERNEL__
	# define EXT2_FRAG_SIZE(s) (EXT2_SB(s)->s_frag_size)
	# define EXT2_FRAGS_PER_BLOCK(s) (EXT2_SB(s)->s_frags_per_block)
	#else
	# define EXT2_FRAG_SIZE(s) (EXT2_MIN_FRAG_SIZE << (s)->s_log_frag_size)
	# define EXT2_FRAGS_PER_BLOCK(s) (EXT2_BLOCK_SIZE(s) / EXT2_FRAG_SIZE(s))
	#endif

	/*
	* ACL structures
	*/
	struct ext2_acl_header /* Header of Access Control Lists */
	{
	__u32 aclh_size;
	__u32 aclh_file_count;
	__u32 aclh_acle_count;
	__u32 aclh_first_acle;
	};

	struct ext2_acl_entry /* Access Control List Entry */
	{
	__u32 acle_size;
	__u16 acle_perms; /* Access permissions */
	__u16 acle_type; /* Type of entry */
	__u16 acle_tag; /* User or group identity */
	__u16 acle_pad1;
	__u32 acle_next; /* Pointer on next entry for the */
	/* same inode or on next free entry */
	};

	/*
	* Structure of a blocks group descriptor
	*/
	struct ext2_group_desc
	{
	__u32 bg_block_bitmap; /* Blocks bitmap block */
	__u32 bg_inode_bitmap; /* Inodes bitmap block */
	__u32 bg_inode_table; /* Inodes table block */
	__u16 bg_free_blocks_count; /* Free blocks count */
	__u16 bg_free_inodes_count; /* Free inodes count */
	__u16 bg_used_dirs_count; /* Directories count */
	__u16 bg_pad;
	__u32 bg_reserved[3];
	};

	/*
	* Data structures used by the directory indexing feature
	*
	* Note: all of the multibyte integer fields are little endian.
	*/

	/*
	* Note: dx_root_info is laid out so that if it should somehow get
	* overlaid by a dirent the two low bits of the hash version will be
	* zero. Therefore, the hash version mod 4 should never be 0.
	* Sincerely, the paranoia department.
	*/
	struct ext2_dx_root_info {
	__u32 reserved_zero;
	__u8 hash_version; /* 0 now, 1 at release */
	__u8 info_length; /* 8 */
	__u8 indirect_levels;
	__u8 unused_flags;
	};

	#define EXT2_HASH_LEGACY 0
	#define EXT2_HASH_HALF_MD4 1
	#define EXT2_HASH_TEA 2

	#define EXT2_HASH_FLAG_INCOMPAT 0x1

	struct ext2_dx_entry {
	__u32 hash;
	__u32 block;
	};

	struct ext2_dx_countlimit {
	__u16 limit;
	__u16 count;
	};


	/*
	* Macro-instructions used to manage group descriptors
	*/
	#define EXT2_BLOCKS_PER_GROUP(s) (EXT2_SB(s)->s_blocks_per_group)
	#define EXT2_INODES_PER_GROUP(s) (EXT2_SB(s)->s_inodes_per_group)
	#define EXT2_INODES_PER_BLOCK(s) (EXT2_BLOCK_SIZE(s)/EXT2_INODE_SIZE(s))
	/* limits imposed by 16-bit value gd_free_{blocks,inode}_count */
	#define EXT2_MAX_BLOCKS_PER_GROUP(s) ((1 << 16) - 8)
	#define EXT2_MAX_INODES_PER_GROUP(s) ((1 << 16) - EXT2_INODES_PER_BLOCK(s))
	#ifdef __KERNEL__
	#define EXT2_DESC_PER_BLOCK(s) (EXT2_SB(s)->s_desc_per_block)
	#define EXT2_DESC_PER_BLOCK_BITS(s) (EXT2_SB(s)->s_desc_per_block_bits)
	#else
	#define EXT2_DESC_PER_BLOCK(s) (EXT2_BLOCK_SIZE(s) / sizeof (struct ext2_group_desc))
	#endif

	/*
	* Constants relative to the data blocks
	*/
	#define EXT2_NDIR_BLOCKS 12
	#define EXT2_IND_BLOCK EXT2_NDIR_BLOCKS
	#define EXT2_DIND_BLOCK (EXT2_IND_BLOCK + 1)
	#define EXT2_TIND_BLOCK (EXT2_DIND_BLOCK + 1)
	#define EXT2_N_BLOCKS (EXT2_TIND_BLOCK + 1)

	/*
	* Inode flags
	*/
	#define EXT2_SECRM_FL 0x00000001 /* Secure deletion */
	#define EXT2_UNRM_FL 0x00000002 /* Undelete */
	#define EXT2_COMPR_FL 0x00000004 /* Compress file */
	#define EXT2_SYNC_FL 0x00000008 /* Synchronous updates */
	#define EXT2_IMMUTABLE_FL 0x00000010 /* Immutable file */
	#define EXT2_APPEND_FL 0x00000020 /* writes to file may only append */
	#define EXT2_NODUMP_FL 0x00000040 /* do not dump file */
	#define EXT2_NOATIME_FL 0x00000080 /* do not update atime */
	/* Reserved for compression usage... */
	#define EXT2_DIRTY_FL 0x00000100
	#define EXT2_COMPRBLK_FL 0x00000200 /* One or more compressed clusters */
	#define EXT2_NOCOMPR_FL 0x00000400 /* Access raw compressed data */
	#define EXT2_ECOMPR_FL 0x00000800 /* Compression error */
	/* End compression flags --- maybe not all used */
	#define EXT2_BTREE_FL 0x00001000 /* btree format dir */
	#define EXT2_INDEX_FL 0x00001000 /* hash-indexed directory */
	#define EXT2_IMAGIC_FL 0x00002000
	#define EXT3_JOURNAL_DATA_FL 0x00004000 /* file data should be journaled */
	#define EXT2_NOTAIL_FL 0x00008000 /* file tail should not be merged */
	#define EXT2_DIRSYNC_FL 0x00010000 /* Synchronous directory modifications */
	#define EXT2_TOPDIR_FL 0x00020000 /* Top of directory hierarchies*/
	#define EXT3_EXTENTS_FL 0x00080000 /* Inode uses extents */
	#define EXT2_RESERVED_FL 0x80000000 /* reserved for ext2 lib */

	#define EXT2_FL_USER_VISIBLE 0x0003DFFF /* User visible flags */
	#define EXT2_FL_USER_MODIFIABLE 0x000080FF /* User modifiable flags */

	/*
	* ioctl commands
	*/
	#define EXT2_IOC_GETFLAGS _IOR('f', 1, long)
	#define EXT2_IOC_SETFLAGS _IOW('f', 2, long)
	#define EXT2_IOC_GETVERSION _IOR('v', 1, long)
	#define EXT2_IOC_SETVERSION _IOW('v', 2, long)

	/*
	* Structure of an inode on the disk
	*/
	struct ext2_inode {
	__u16 i_mode; /* File mode */
	__u16 i_uid; /* Low 16 bits of Owner Uid */
	__u32 i_size; /* Size in bytes */
	__u32 i_atime; /* Access time */
	__u32 i_ctime; /* Creation time */
	__u32 i_mtime; /* Modification time */
	__u32 i_dtime; /* Deletion Time */
	__u16 i_gid; /* Low 16 bits of Group Id */
	__u16 i_links_count; /* Links count */
	__u32 i_blocks; /* Blocks count */
	__u32 i_flags; /* File flags */
	union {
	struct {
	__u32 l_i_reserved1;
	} linux1;
	struct {
	__u32 h_i_translator;
	} hurd1;
	struct {
	__u32 m_i_reserved1;
	} masix1;
	} osd1; /* OS dependent 1 */
	__u32 i_block[EXT2_N_BLOCKS];/* Pointers to blocks */
	__u32 i_generation; /* File version (for NFS) */
	__u32 i_file_acl; /* File ACL */
	__u32 i_dir_acl; /* Directory ACL */
	__u32 i_faddr; /* Fragment address */
	union {
	struct {
	__u8 l_i_frag; /* Fragment number */
	__u8 l_i_fsize; /* Fragment size */
	__u16 i_pad1;
	__u16 l_i_uid_high; /* these 2 fields */
	__u16 l_i_gid_high; /* were reserved2[0] */
	__u32 l_i_reserved2;
	} linux2;
	struct {
	__u8 h_i_frag; /* Fragment number */
	__u8 h_i_fsize; /* Fragment size */
	__u16 h_i_mode_high;
	__u16 h_i_uid_high;
	__u16 h_i_gid_high;
	__u32 h_i_author;
	} hurd2;
	struct {
	__u8 m_i_frag; /* Fragment number */
	__u8 m_i_fsize; /* Fragment size */
	__u16 m_pad1;
	__u32 m_i_reserved2[2];
	} masix2;
	} osd2; /* OS dependent 2 */
	};

	/*
	* Permanent part of an large inode on the disk
	*/
	struct ext2_inode_large {
	__u16 i_mode; /* File mode */
	__u16 i_uid; /* Low 16 bits of Owner Uid */
	__u32 i_size; /* Size in bytes */
	__u32 i_atime; /* Access time */
	__u32 i_ctime; /* Creation time */
	__u32 i_mtime; /* Modification time */
	__u32 i_dtime; /* Deletion Time */
	__u16 i_gid; /* Low 16 bits of Group Id */
	__u16 i_links_count; /* Links count */
	__u32 i_blocks; /* Blocks count */
	__u32 i_flags; /* File flags */
	union {
	struct {
	__u32 l_i_reserved1;
	} linux1;
	struct {
	__u32 h_i_translator;
	} hurd1;
	struct {
	__u32 m_i_reserved1;
	} masix1;
	} osd1; /* OS dependent 1 */
	__u32 i_block[EXT2_N_BLOCKS];/* Pointers to blocks */
	__u32 i_generation; /* File version (for NFS) */
	__u32 i_file_acl; /* File ACL */
	__u32 i_dir_acl; /* Directory ACL */
	__u32 i_faddr; /* Fragment address */
	union {
	struct {
	__u8 l_i_frag; /* Fragment number */
	__u8 l_i_fsize; /* Fragment size */
	__u16 i_pad1;
	__u16 l_i_uid_high; /* these 2 fields */
	__u16 l_i_gid_high; /* were reserved2[0] */
	__u32 l_i_reserved2;
	} linux2;
	struct {
	__u8 h_i_frag; /* Fragment number */
	__u8 h_i_fsize; /* Fragment size */
	__u16 h_i_mode_high;
	__u16 h_i_uid_high;
	__u16 h_i_gid_high;
	__u32 h_i_author;
	} hurd2;
	struct {
	__u8 m_i_frag; /* Fragment number */
	__u8 m_i_fsize; /* Fragment size */
	__u16 m_pad1;
	__u32 m_i_reserved2[2];
	} masix2;
	} osd2; /* OS dependent 2 */
	__u16 i_extra_isize;
	__u16 i_pad1;
	};

	#define i_size_high i_dir_acl

	#if defined(__KERNEL__) \|\| defined(__linux__)
	#define i_reserved1 osd1.linux1.l_i_reserved1
	#define i_frag osd2.linux2.l_i_frag
	#define i_fsize osd2.linux2.l_i_fsize
	#define i_uid_low i_uid
	#define i_gid_low i_gid
	#define i_uid_high osd2.linux2.l_i_uid_high
	#define i_gid_high osd2.linux2.l_i_gid_high
	#define i_reserved2 osd2.linux2.l_i_reserved2

	#else
	#if defined(__GNU__)

	#define i_translator osd1.hurd1.h_i_translator
	#define i_frag osd2.hurd2.h_i_frag;
	#define i_fsize osd2.hurd2.h_i_fsize;
	#define i_uid_high osd2.hurd2.h_i_uid_high
	#define i_gid_high osd2.hurd2.h_i_gid_high
	#define i_author osd2.hurd2.h_i_author

	#else
	#if defined(__masix__)

	#define i_reserved1 osd1.masix1.m_i_reserved1
	#define i_frag osd2.masix2.m_i_frag
	#define i_fsize osd2.masix2.m_i_fsize
	#define i_reserved2 osd2.masix2.m_i_reserved2

	#endif /* __masix__ */
	#endif /* __GNU__ */
	#endif /* defined(__KERNEL__) \|\| defined(__linux__) */

	/*
	* File system states
	*/
	#define EXT2_VALID_FS 0x0001 /* Unmounted cleanly */
	#define EXT2_ERROR_FS 0x0002 /* Errors detected */

	/*
	* Mount flags
	*/
	#define EXT2_MOUNT_CHECK 0x0001 /* Do mount-time checks */
	#define EXT2_MOUNT_GRPID 0x0004 /* Create files with directory's group */
	#define EXT2_MOUNT_DEBUG 0x0008 /* Some debugging messages */
	#define EXT2_MOUNT_ERRORS_CONT 0x0010 /* Continue on errors */
	#define EXT2_MOUNT_ERRORS_RO 0x0020 /* Remount fs ro on errors */
	#define EXT2_MOUNT_ERRORS_PANIC 0x0040 /* Panic on errors */
	#define EXT2_MOUNT_MINIX_DF 0x0080 /* Mimics the Minix statfs */
	#define EXT2_MOUNT_NO_UID32 0x0200 /* Disable 32-bit UIDs */

	#define clear_opt(o, opt) o &= ~EXT2_MOUNT_##opt
	#define set_opt(o, opt) o \|= EXT2_MOUNT_##opt
	#define test_opt(sb, opt) (EXT2_SB(sb)->s_mount_opt & \
	EXT2_MOUNT_##opt)
	/*
	* Maximal mount counts between two filesystem checks
	*/
	#define EXT2_DFL_MAX_MNT_COUNT 20 /* Allow 20 mounts */
	#define EXT2_DFL_CHECKINTERVAL 0 /* Don't use interval check */

	/*
	* Behaviour when detecting errors
	*/
	#define EXT2_ERRORS_CONTINUE 1 /* Continue execution */
	#define EXT2_ERRORS_RO 2 /* Remount fs read-only */
	#define EXT2_ERRORS_PANIC 3 /* Panic */
	#define EXT2_ERRORS_DEFAULT EXT2_ERRORS_CONTINUE

	/*
	* Structure of the super block
	*/
	struct ext2_super_block {
	__u32 s_inodes_count; /* Inodes count */
	__u32 s_blocks_count; /* Blocks count */
	__u32 s_r_blocks_count; /* Reserved blocks count */
	__u32 s_free_blocks_count; /* Free blocks count */
	__u32 s_free_inodes_count; /* Free inodes count */
	__u32 s_first_data_block; /* First Data Block */
	__u32 s_log_block_size; /* Block size */
	__s32 s_log_frag_size; /* Fragment size */
	__u32 s_blocks_per_group; /* # Blocks per group */
	__u32 s_frags_per_group; /* # Fragments per group */
	__u32 s_inodes_per_group; /* # Inodes per group */
	__u32 s_mtime; /* Mount time */
	__u32 s_wtime; /* Write time */
	__u16 s_mnt_count; /* Mount count */
	__s16 s_max_mnt_count; /* Maximal mount count */
	__u16 s_magic; /* Magic signature */
	__u16 s_state; /* File system state */
	__u16 s_errors; /* Behaviour when detecting errors */
	__u16 s_minor_rev_level; /* minor revision level */
	__u32 s_lastcheck; /* time of last check */
	__u32 s_checkinterval; /* max. time between checks */
	__u32 s_creator_os; /* OS */
	__u32 s_rev_level; /* Revision level */
	__u16 s_def_resuid; /* Default uid for reserved blocks */
	__u16 s_def_resgid; /* Default gid for reserved blocks */
	/*
	* These fields are for EXT2_DYNAMIC_REV superblocks only.
	*
	* Note: the difference between the compatible feature set and
	* the incompatible feature set is that if there is a bit set
	* in the incompatible feature set that the kernel doesn't
	* know about, it should refuse to mount the filesystem.
	*
	* e2fsck's requirements are more strict; if it doesn't know
	* about a feature in either the compatible or incompatible
	* feature set, it must abort and not try to meddle with
	* things it doesn't understand...
	*/
	__u32 s_first_ino; /* First non-reserved inode */
	__u16 s_inode_size; /* size of inode structure */
	__u16 s_block_group_nr; /* block group # of this superblock */
	__u32 s_feature_compat; /* compatible feature set */
	__u32 s_feature_incompat; /* incompatible feature set */
	__u32 s_feature_ro_compat; /* readonly-compatible feature set */
	__u8 s_uuid[16]; /* 128-bit uuid for volume */
	char s_volume_name[16]; /* volume name */
	char s_last_mounted[64]; /* directory where last mounted */
	__u32 s_algorithm_usage_bitmap; /* For compression */
	/*
	* Performance hints. Directory preallocation should only
	* happen if the EXT2_FEATURE_COMPAT_DIR_PREALLOC flag is on.
	*/
	__u8 s_prealloc_blocks; /* Nr of blocks to try to preallocate*/
	__u8 s_prealloc_dir_blocks; /* Nr to preallocate for dirs */
	__u16 s_reserved_gdt_blocks; /* Per group table for online growth */
	/*
	* Journaling support valid if EXT2_FEATURE_COMPAT_HAS_JOURNAL set.
	*/
	__u8 s_journal_uuid[16]; /* uuid of journal superblock */
	__u32 s_journal_inum; /* inode number of journal file */
	__u32 s_journal_dev; /* device number of journal file */
	__u32 s_last_orphan; /* start of list of inodes to delete */
	__u32 s_hash_seed[4]; /* HTREE hash seed */
	__u8 s_def_hash_version; /* Default hash version to use */
	__u8 s_jnl_backup_type; /* Default type of journal backup */
	__u16 s_reserved_word_pad;
	__u32 s_default_mount_opts;
	__u32 s_first_meta_bg; /* First metablock group */
	__u32 s_mkfs_time; /* When the filesystem was created */
	__u32 s_jnl_blocks[17]; /* Backup of the journal inode */
	__u32 s_reserved[172]; /* Padding to the end of the block */
	};

	/*
	* Codes for operating systems
	*/
	#define EXT2_OS_LINUX 0
	#define EXT2_OS_HURD 1
	#define EXT2_OS_MASIX 2
	#define EXT2_OS_FREEBSD 3
	#define EXT2_OS_LITES 4

	/*
	* Revision levels
	*/
	#define EXT2_GOOD_OLD_REV 0 /* The good old (original) format */
	#define EXT2_DYNAMIC_REV 1 /* V2 format w/ dynamic inode sizes */

	#define EXT2_CURRENT_REV EXT2_GOOD_OLD_REV
	#define EXT2_MAX_SUPP_REV EXT2_DYNAMIC_REV

	#define EXT2_GOOD_OLD_INODE_SIZE 128

	/*
	* Journal inode backup types
	*/
	#define EXT3_JNL_BACKUP_BLOCKS 1

	/*
	* Feature set definitions
	*/

	#define EXT2_HAS_COMPAT_FEATURE(sb,mask) \
	( EXT2_SB(sb)->s_feature_compat & (mask) )
	#define EXT2_HAS_RO_COMPAT_FEATURE(sb,mask) \
	( EXT2_SB(sb)->s_feature_ro_compat & (mask) )
	#define EXT2_HAS_INCOMPAT_FEATURE(sb,mask) \
	( EXT2_SB(sb)->s_feature_incompat & (mask) )

	#define EXT2_FEATURE_COMPAT_DIR_PREALLOC 0x0001
	#define EXT2_FEATURE_COMPAT_IMAGIC_INODES 0x0002
	#define EXT3_FEATURE_COMPAT_HAS_JOURNAL 0x0004
	#define EXT2_FEATURE_COMPAT_EXT_ATTR 0x0008
	#define EXT2_FEATURE_COMPAT_RESIZE_INODE 0x0010
	#define EXT2_FEATURE_COMPAT_DIR_INDEX 0x0020

	#define EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER 0x0001
	#define EXT2_FEATURE_RO_COMPAT_LARGE_FILE 0x0002
	/* #define EXT2_FEATURE_RO_COMPAT_BTREE_DIR 0x0004 not used */

	#define EXT2_FEATURE_INCOMPAT_COMPRESSION 0x0001
	#define EXT2_FEATURE_INCOMPAT_FILETYPE 0x0002
	#define EXT3_FEATURE_INCOMPAT_RECOVER 0x0004 /* Needs recovery */
	#define EXT3_FEATURE_INCOMPAT_JOURNAL_DEV 0x0008 /* Journal device */
	#define EXT2_FEATURE_INCOMPAT_META_BG 0x0010
	#define EXT3_FEATURE_INCOMPAT_EXTENTS 0x0040


	#define EXT2_FEATURE_COMPAT_SUPP 0
	#define EXT2_FEATURE_INCOMPAT_SUPP (EXT2_FEATURE_INCOMPAT_FILETYPE)
	#define EXT2_FEATURE_RO_COMPAT_SUPP (EXT2_FEATURE_RO_COMPAT_SPARSE_SUPER\| \
	EXT2_FEATURE_RO_COMPAT_LARGE_FILE\| \
	EXT2_FEATURE_RO_COMPAT_BTREE_DIR)

	/*
	* Default values for user and/or group using reserved blocks
	*/
	#define EXT2_DEF_RESUID 0
	#define EXT2_DEF_RESGID 0

	/*
	* Default mount options
	*/
	#define EXT2_DEFM_DEBUG 0x0001
	#define EXT2_DEFM_BSDGROUPS 0x0002
	#define EXT2_DEFM_XATTR_USER 0x0004
	#define EXT2_DEFM_ACL 0x0008
	#define EXT2_DEFM_UID16 0x0010
	#define EXT3_DEFM_JMODE 0x0060
	#define EXT3_DEFM_JMODE_DATA 0x0020
	#define EXT3_DEFM_JMODE_ORDERED 0x0040
	#define EXT3_DEFM_JMODE_WBACK 0x0060

	/*
	* Structure of a directory entry
	*/
	#define EXT2_NAME_LEN 255

	struct ext2_dir_entry {
	__u32 inode; /* Inode number */
	__u16 rec_len; /* Directory entry length */
	__u16 name_len; /* Name length */
	char name[EXT2_NAME_LEN]; /* File name */
	};

	/*
	* The new version of the directory entry. Since EXT2 structures are
	* stored in intel byte order, and the name_len field could never be
	* bigger than 255 chars, it's safe to reclaim the extra byte for the
	* file_type field.
	*/
	struct ext2_dir_entry_2 {
	__u32 inode; /* Inode number */
	__u16 rec_len; /* Directory entry length */
	__u8 name_len; /* Name length */
	__u8 file_type;
	char name[EXT2_NAME_LEN]; /* File name */
	};

	/*
	* Ext2 directory file types. Only the low 3 bits are used. The
	* other bits are reserved for now.
	*/
	#define EXT2_FT_UNKNOWN 0
	#define EXT2_FT_REG_FILE 1
	#define EXT2_FT_DIR 2
	#define EXT2_FT_CHRDEV 3
	#define EXT2_FT_BLKDEV 4
	#define EXT2_FT_FIFO 5
	#define EXT2_FT_SOCK 6
	#define EXT2_FT_SYMLINK 7

	#define EXT2_FT_MAX 8

	/*
	* EXT2_DIR_PAD defines the directory entries boundaries
	*
	* NOTE: It must be a multiple of 4
	*/
	#define EXT2_DIR_PAD 4
	#define EXT2_DIR_ROUND (EXT2_DIR_PAD - 1)
	#define EXT2_DIR_REC_LEN(name_len) (((name_len) + 8 + EXT2_DIR_ROUND) & \
	~EXT2_DIR_ROUND)

	#endif /* _LINUX_EXT2_FS_H */