text: /*
   *  ext4.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 _EXT4_H
  #define _EXT4_H
  
  #include <linux/types.h>
  #include <linux/blkdev.h>
  #include <linux/magic.h>
  #include <linux/jbd2.h>
  #include <linux/quota.h>
  #include <linux/rwsem.h>
  #include <linux/rbtree.h>
  #include <linux/seqlock.h>
  #include <linux/mutex.h>
  #include <linux/timer.h>
  #include <linux/wait.h>
  #include <linux/blockgroup_lock.h>
  #include <linux/percpu_counter.h>
  #ifdef __KERNEL__
  #include <linux/compat.h>
  #endif
  
  /*
   * The fourth extended filesystem constants/structures
   */
  
  /*
   * Define EXT4FS_DEBUG to produce debug messages
   */
  #undef EXT4FS_DEBUG
  
  /*
   * Debug code
   */
  #ifdef EXT4FS_DEBUG
  #define ext4_debug(f, a...)						\
  	do {								\
  		printk(KERN_DEBUG "EXT4-fs DEBUG (%s, %d): %s:",	\
  			__FILE__, __LINE__, __func__);			\
  		printk(KERN_DEBUG f, ## a);				\
  	} while (0)
  #else
  #define ext4_debug(f, a...)	do {} while (0)
  #endif
  
  #define EXT4_ERROR_INODE(inode, fmt, a...) \
  	ext4_error_inode((inode), __func__, __LINE__, 0, (fmt), ## a)
  
  #define EXT4_ERROR_INODE_BLOCK(inode, block, fmt, a...)			\
  	ext4_error_inode((inode), __func__, __LINE__, (block), (fmt), ## a)
  
  #define EXT4_ERROR_FILE(file, block, fmt, a...)				\
  	ext4_error_file((file), __func__, __LINE__, (block), (fmt), ## a)
  
  /* data type for block offset of block group */
  typedef int ext4_grpblk_t;
  
  /* data type for filesystem-wide blocks number */
  typedef unsigned long long ext4_fsblk_t;
  
  /* data type for file logical block number */
  typedef __u32 ext4_lblk_t;
  
  /* data type for block group number */
  typedef unsigned int ext4_group_t;
  
  /*
   * Flags used in mballoc's allocation_context flags field.
   *
   * Also used to show what's going on for debugging purposes when the
   * flag field is exported via the traceport interface
   */
  
  /* prefer goal again. length */
  #define EXT4_MB_HINT_MERGE		0x0001
  /* blocks already reserved */
  #define EXT4_MB_HINT_RESERVED		0x0002
  /* metadata is being allocated */
  #define EXT4_MB_HINT_METADATA		0x0004
  /* first blocks in the file */
  #define EXT4_MB_HINT_FIRST		0x0008
  /* search for the best chunk */
  #define EXT4_MB_HINT_BEST		0x0010
  /* data is being allocated */
  #define EXT4_MB_HINT_DATA		0x0020
  /* don't preallocate (for tails) */
  #define EXT4_MB_HINT_NOPREALLOC		0x0040
  /* allocate for locality group */
  #define EXT4_MB_HINT_GROUP_ALLOC	0x0080
  /* allocate goal blocks or none */
  #define EXT4_MB_HINT_GOAL_ONLY		0x0100
  /* goal is meaningful */
  #define EXT4_MB_HINT_TRY_GOAL		0x0200
  /* blocks already pre-reserved by delayed allocation */
  #define EXT4_MB_DELALLOC_RESERVED	0x0400
  /* We are doing stream allocation */
  #define EXT4_MB_STREAM_ALLOC		0x0800
  /* Use reserved root blocks if needed */
  #define EXT4_MB_USE_ROOT_BLOCKS		0x1000
  
  struct ext4_allocation_request {
  	/* target inode for block we're allocating */
  	struct inode *inode;
  	/* how many blocks we want to allocate */
  	unsigned int len;
  	/* logical block in target inode */
  	ext4_lblk_t logical;
  	/* the closest logical allocated block to the left */
  	ext4_lblk_t lleft;
  	/* the closest logical allocated block to the right */
  	ext4_lblk_t lright;
  	/* phys. target (a hint) */
  	ext4_fsblk_t goal;
  	/* phys. block for the closest logical allocated block to the left */
  	ext4_fsblk_t pleft;
  	/* phys. block for the closest logical allocated block to the right */
  	ext4_fsblk_t pright;
  	/* flags. see above EXT4_MB_HINT_* */
  	unsigned int flags;
  };
  
  /*
   * Logical to physical block mapping, used by ext4_map_blocks()
   *
   * This structure is used to pass requests into ext4_map_blocks() as
   * well as to store the information returned by ext4_map_blocks().  It
   * takes less room on the stack than a struct buffer_head.
   */
  #define EXT4_MAP_NEW		(1 << BH_New)
  #define EXT4_MAP_MAPPED		(1 << BH_Mapped)
  #define EXT4_MAP_UNWRITTEN	(1 << BH_Unwritten)
  #define EXT4_MAP_BOUNDARY	(1 << BH_Boundary)
  #define EXT4_MAP_UNINIT		(1 << BH_Uninit)
  #define EXT4_MAP_FLAGS		(EXT4_MAP_NEW | EXT4_MAP_MAPPED |\
  				 EXT4_MAP_UNWRITTEN | EXT4_MAP_BOUNDARY |\
  				 EXT4_MAP_UNINIT)
  
  struct ext4_map_blocks {
  	ext4_fsblk_t m_pblk;
  	ext4_lblk_t m_lblk;
  	unsigned int m_len;
  	unsigned int m_flags;
  };
  
  /*
   * For delayed allocation tracking
   */
  struct mpage_da_data {
  	struct inode *inode;
  	sector_t b_blocknr;		/* start block number of extent */
  	size_t b_size;			/* size of extent */
  	unsigned long b_state;		/* state of the extent */
  	unsigned long first_page, next_page;	/* extent of pages */
  	struct writeback_control *wbc;
  	int io_done;
  	int pages_written;
  	int retval;
  };
  
  /*
   * Flags for ext4_io_end->flags
   */
  #define	EXT4_IO_END_UNWRITTEN	0x0001
  #define EXT4_IO_END_ERROR	0x0002
  
  struct ext4_io_page {
  	struct page	*p_page;
  	atomic_t	p_count;
  };
  
  #define MAX_IO_PAGES 128
  
  typedef struct ext4_io_end {
  	struct list_head	list;		/* per-file finished IO list */
  	struct inode		*inode;		/* file being written to */
  	unsigned int		flag;		/* unwritten or not */
  	struct page		*page;		/* page struct for buffer write */
  	loff_t			offset;		/* offset in the file */
  	ssize_t			size;		/* size of the extent */
  	struct work_struct	work;		/* data work queue */
  	struct kiocb		*iocb;		/* iocb struct for AIO */
  	int			result;		/* error value for AIO */
  	int			num_io_pages;
  	struct ext4_io_page	*pages[MAX_IO_PAGES];
  } ext4_io_end_t;
  
  struct ext4_io_submit {
  	int			io_op;
  	struct bio		*io_bio;
  	ext4_io_end_t		*io_end;
  	struct ext4_io_page	*io_page;
  	sector_t		io_next_block;
  };
  
  /*
   * Special inodes numbers
   */
  #define	EXT4_BAD_INO		 1	/* Bad blocks inode */
  #define EXT4_ROOT_INO		 2	/* Root inode */
  #define EXT4_USR_QUOTA_INO	 3	/* User quota inode */
  #define EXT4_GRP_QUOTA_INO	 4	/* Group quota inode */
  #define EXT4_BOOT_LOADER_INO	 5	/* Boot loader inode */
  #define EXT4_UNDEL_DIR_INO	 6	/* Undelete directory inode */
  #define EXT4_RESIZE_INO		 7	/* Reserved group descriptors inode */
  #define EXT4_JOURNAL_INO	 8	/* Journal inode */
  
  /* First non-reserved inode for old ext4 filesystems */
  #define EXT4_GOOD_OLD_FIRST_INO	11
  
  /*
   * Maximal count of links to a file
   */
  #define EXT4_LINK_MAX		65000
  
  /*
   * Macro-instructions used to manage several block sizes
   */
  #define EXT4_MIN_BLOCK_SIZE		1024
  #define	EXT4_MAX_BLOCK_SIZE		65536
  #define EXT4_MIN_BLOCK_LOG_SIZE		10
  #define EXT4_MAX_BLOCK_LOG_SIZE		16
  #ifdef __KERNEL__
  # define EXT4_BLOCK_SIZE(s)		((s)->s_blocksize)
  #else
  # define EXT4_BLOCK_SIZE(s)		(EXT4_MIN_BLOCK_SIZE << (s)->s_log_block_size)
  #endif
  #define	EXT4_ADDR_PER_BLOCK(s)		(EXT4_BLOCK_SIZE(s) / sizeof(__u32))
  #ifdef __KERNEL__
  # define EXT4_BLOCK_SIZE_BITS(s)	((s)->s_blocksize_bits)
  #else
  # define EXT4_BLOCK_SIZE_BITS(s)	((s)->s_log_block_size + 10)
  #endif
  #ifdef __KERNEL__
  #define	EXT4_ADDR_PER_BLOCK_BITS(s)	(EXT4_SB(s)->s_addr_per_block_bits)
  #define EXT4_INODE_SIZE(s)		(EXT4_SB(s)->s_inode_size)
  #define EXT4_FIRST_INO(s)		(EXT4_SB(s)->s_first_ino)
  #else
  #define EXT4_INODE_SIZE(s)	(((s)->s_rev_level == EXT4_GOOD_OLD_REV) ? \
  				 EXT4_GOOD_OLD_INODE_SIZE : \
  				 (s)->s_inode_size)
  #define EXT4_FIRST_INO(s)	(((s)->s_rev_level == EXT4_GOOD_OLD_REV) ? \
  				 EXT4_GOOD_OLD_FIRST_INO : \
  				 (s)->s_first_ino)
  #endif
  #define EXT4_BLOCK_ALIGN(size, blkbits)		ALIGN((size), (1 << (blkbits)))
  
  /*
   * Structure of a blocks group descriptor
   */
  struct ext4_group_desc
  {
  	__le32	bg_block_bitmap_lo;	/* Blocks bitmap block */
  	__le32	bg_inode_bitmap_lo;	/* Inodes bitmap block */
  	__le32	bg_inode_table_lo;	/* Inodes table block */
  	__le16	bg_free_blocks_count_lo;/* Free blocks count */
  	__le16	bg_free_inodes_count_lo;/* Free inodes count */
  	__le16	bg_used_dirs_count_lo;	/* Directories count */
  	__le16	bg_flags;		/* EXT4_BG_flags (INODE_UNINIT, etc) */
  	__u32	bg_reserved[2];		/* Likely block/inode bitmap checksum */
  	__le16  bg_itable_unused_lo;	/* Unused inodes count */
  	__le16  bg_checksum;		/* crc16(sb_uuid+group+desc) */
  	__le32	bg_block_bitmap_hi;	/* Blocks bitmap block MSB */
  	__le32	bg_inode_bitmap_hi;	/* Inodes bitmap block MSB */
  	__le32	bg_inode_table_hi;	/* Inodes table block MSB */
  	__le16	bg_free_blocks_count_hi;/* Free blocks count MSB */
  	__le16	bg_free_inodes_count_hi;/* Free inodes count MSB */
  	__le16	bg_used_dirs_count_hi;	/* Directories count MSB */
  	__le16  bg_itable_unused_hi;    /* Unused inodes count MSB */
  	__u32	bg_reserved2[3];
  };
  
  /*
   * Structure of a flex block group info
   */
  
  struct flex_groups {
  	atomic_t free_inodes;
  	atomic_t free_blocks;
  	atomic_t used_dirs;
  };
  
  #define EXT4_BG_INODE_UNINIT	0x0001 /* Inode table/bitmap not in use */
  #define EXT4_BG_BLOCK_UNINIT	0x0002 /* Block bitmap not in use */
  #define EXT4_BG_INODE_ZEROED	0x0004 /* On-disk itable initialized to zero */
  
  /*
   * Macro-instructions used to manage group descriptors
   */
  #define EXT4_MIN_DESC_SIZE		32
  #define EXT4_MIN_DESC_SIZE_64BIT	64
  #define	EXT4_MAX_DESC_SIZE		EXT4_MIN_BLOCK_SIZE
  #define EXT4_DESC_SIZE(s)		(EXT4_SB(s)->s_desc_size)
  #ifdef __KERNEL__
  # define EXT4_BLOCKS_PER_GROUP(s)	(EXT4_SB(s)->s_blocks_per_group)
  # define EXT4_DESC_PER_BLOCK(s)		(EXT4_SB(s)->s_desc_per_block)
  # define EXT4_INODES_PER_GROUP(s)	(EXT4_SB(s)->s_inodes_per_group)
  # define EXT4_DESC_PER_BLOCK_BITS(s)	(EXT4_SB(s)->s_desc_per_block_bits)
  #else
  # define EXT4_BLOCKS_PER_GROUP(s)	((s)->s_blocks_per_group)
  # define EXT4_DESC_PER_BLOCK(s)		(EXT4_BLOCK_SIZE(s) / EXT4_DESC_SIZE(s))
  # define EXT4_INODES_PER_GROUP(s)	((s)->s_inodes_per_group)
  #endif
  
  /*
   * Constants relative to the data blocks
   */
  #define	EXT4_NDIR_BLOCKS		12
  #define	EXT4_IND_BLOCK			EXT4_NDIR_BLOCKS
  #define	EXT4_DIND_BLOCK			(EXT4_IND_BLOCK + 1)
  #define	EXT4_TIND_BLOCK			(EXT4_DIND_BLOCK + 1)
  #define	EXT4_N_BLOCKS			(EXT4_TIND_BLOCK + 1)
  
  /*
   * Inode flags
   */
  #define	EXT4_SECRM_FL			0x00000001 /* Secure deletion */
  #define	EXT4_UNRM_FL			0x00000002 /* Undelete */
  #define	EXT4_COMPR_FL			0x00000004 /* Compress file */
  #define EXT4_SYNC_FL			0x00000008 /* Synchronous updates */
  #define EXT4_IMMUTABLE_FL		0x00000010 /* Immutable file */
  #define EXT4_APPEND_FL			0x00000020 /* writes to file may only append */
  #define EXT4_NODUMP_FL			0x00000040 /* do not dump file */
  #define EXT4_NOATIME_FL			0x00000080 /* do not update atime */
  /* Reserved for compression usage... */
  #define EXT4_DIRTY_FL			0x00000100
  #define EXT4_COMPRBLK_FL		0x00000200 /* One or more compressed clusters */
  #define EXT4_NOCOMPR_FL			0x00000400 /* Don't compress */
  #define EXT4_ECOMPR_FL			0x00000800 /* Compression error */
  /* End compression flags --- maybe not all used */
  #define EXT4_INDEX_FL			0x00001000 /* hash-indexed directory */
  #define EXT4_IMAGIC_FL			0x00002000 /* AFS directory */
  #define EXT4_JOURNAL_DATA_FL		0x00004000 /* file data should be journaled */
  #define EXT4_NOTAIL_FL			0x00008000 /* file tail should not be merged */
  #define EXT4_DIRSYNC_FL			0x00010000 /* dirsync behaviour (directories only) */
  #define EXT4_TOPDIR_FL			0x00020000 /* Top of directory hierarchies*/
  #define EXT4_HUGE_FILE_FL               0x00040000 /* Set to each huge file */
  #define EXT4_EXTENTS_FL			0x00080000 /* Inode uses extents */
  #define EXT4_EA_INODE_FL	        0x00200000 /* Inode used for large EA */
  #define EXT4_EOFBLOCKS_FL		0x00400000 /* Blocks allocated beyond EOF */
  #define EXT4_RESERVED_FL		0x80000000 /* reserved for ext4 lib */
  
  #define EXT4_FL_USER_VISIBLE		0x004BDFFF /* User visible flags */
  #define EXT4_FL_USER_MODIFIABLE		0x004B80FF /* User modifiable flags */
  
  /* Flags that should be inherited by new inodes from their parent. */
  #define EXT4_FL_INHERITED (EXT4_SECRM_FL | EXT4_UNRM_FL | EXT4_COMPR_FL |\
  			   EXT4_SYNC_FL | EXT4_IMMUTABLE_FL | EXT4_APPEND_FL |\
  			   EXT4_NODUMP_FL | EXT4_NOATIME_FL |\
  			   EXT4_NOCOMPR_FL | EXT4_JOURNAL_DATA_FL |\
  			   EXT4_NOTAIL_FL | EXT4_DIRSYNC_FL)
  
  /* Flags that are appropriate for regular files (all but dir-specific ones). */
  #define EXT4_REG_FLMASK (~(EXT4_DIRSYNC_FL | EXT4_TOPDIR_FL))
  
  /* Flags that are appropriate for non-directories/regular files. */
  #define EXT4_OTHER_FLMASK (EXT4_NODUMP_FL | EXT4_NOATIME_FL)
  
  /* Mask out flags that are inappropriate for the given type of inode. */
  static inline __u32 ext4_mask_flags(umode_t mode, __u32 flags)
  {
  	if (S_ISDIR(mode))
  		return flags;
  	else if (S_ISREG(mode))
  		return flags & EXT4_REG_FLMASK;
  	else
  		return flags & EXT4_OTHER_FLMASK;
  }
  
  /*
   * Inode flags used for atomic set/get
   */
  enum {
  	EXT4_INODE_SECRM	= 0,	/* Secure deletion */
  	EXT4_INODE_UNRM		= 1,	/* Undelete */
  	EXT4_INODE_COMPR	= 2,	/* Compress file */
  	EXT4_INODE_SYNC		= 3,	/* Synchronous updates */
  	EXT4_INODE_IMMUTABLE	= 4,	/* Immutable file */
  	EXT4_INODE_APPEND	= 5,	/* writes to file may only append */
  	EXT4_INODE_NODUMP	= 6,	/* do not dump file */
  	EXT4_INODE_NOATIME	= 7,	/* do not update atime */
  /* Reserved for compression usage... */
  	EXT4_INODE_DIRTY	= 8,
  	EXT4_INODE_COMPRBLK	= 9,	/* One or more compressed clusters */
  	EXT4_INODE_NOCOMPR	= 10,	/* Don't compress */
  	EXT4_INODE_ECOMPR	= 11,	/* Compression error */
  /* End compression flags --- maybe not all used */
  	EXT4_INODE_INDEX	= 12,	/* hash-indexed directory */
  	EXT4_INODE_IMAGIC	= 13,	/* AFS directory */
  	EXT4_INODE_JOURNAL_DATA	= 14,	/* file data should be journaled */
  	EXT4_INODE_NOTAIL	= 15,	/* file tail should not be merged */
  	EXT4_INODE_DIRSYNC	= 16,	/* dirsync behaviour (directories only) */
  	EXT4_INODE_TOPDIR	= 17,	/* Top of directory hierarchies*/
  	EXT4_INODE_HUGE_FILE	= 18,	/* Set to each huge file */
  	EXT4_INODE_EXTENTS	= 19,	/* Inode uses extents */
  	EXT4_INODE_EA_INODE	= 21,	/* Inode used for large EA */
  	EXT4_INODE_EOFBLOCKS	= 22,	/* Blocks allocated beyond EOF */
  	EXT4_INODE_RESERVED	= 31,	/* reserved for ext4 lib */
  };
  
  #define TEST_FLAG_VALUE(FLAG) (EXT4_##FLAG##_FL == (1 << EXT4_INODE_##FLAG))
  #define CHECK_FLAG_VALUE(FLAG) if (!TEST_FLAG_VALUE(FLAG)) { \
  	printk(KERN_EMERG "EXT4 flag fail: " #FLAG ": %d %d\n", \
  		EXT4_##FLAG##_FL, EXT4_INODE_##FLAG); BUG_ON(1); }
  
  /*
   * Since it's pretty easy to mix up bit numbers and hex values, and we
   * can't do a compile-time test for ENUM values, we use a run-time
   * test to make sure that EXT4_XXX_FL is consistent with respect to
   * EXT4_INODE_XXX.  If all is well the printk and BUG_ON will all drop
   * out so it won't cost any extra space in the compiled kernel image.
   * But it's important that these values are the same, since we are
   * using EXT4_INODE_XXX to test for the flag values, but EXT4_XX_FL
   * must be consistent with the values of FS_XXX_FL defined in
   * include/linux/fs.h and the on-disk values found in ext2, ext3, and
   * ext4 filesystems, and of course the values defined in e2fsprogs.
   *
   * It's not paranoia if the Murphy's Law really *is* out to get you.  :-)
   */
  static inline void ext4_check_flag_values(void)
  {
  	CHECK_FLAG_VALUE(SECRM);
  	CHECK_FLAG_VALUE(UNRM);
  	CHECK_FLAG_VALUE(COMPR);
  	CHECK_FLAG_VALUE(SYNC);
  	CHECK_FLAG_VALUE(IMMUTABLE);
  	CHECK_FLAG_VALUE(APPEND);
  	CHECK_FLAG_VALUE(NODUMP);
  	CHECK_FLAG_VALUE(NOATIME);
  	CHECK_FLAG_VALUE(DIRTY);
  	CHECK_FLAG_VALUE(COMPRBLK);
  	CHECK_FLAG_VALUE(NOCOMPR);
  	CHECK_FLAG_VALUE(ECOMPR);
  	CHECK_FLAG_VALUE(INDEX);
  	CHECK_FLAG_VALUE(IMAGIC);
  	CHECK_FLAG_VALUE(JOURNAL_DATA);
  	CHECK_FLAG_VALUE(NOTAIL);
  	CHECK_FLAG_VALUE(DIRSYNC);
  	CHECK_FLAG_VALUE(TOPDIR);
  	CHECK_FLAG_VALUE(HUGE_FILE);
  	CHECK_FLAG_VALUE(EXTENTS);
  	CHECK_FLAG_VALUE(EA_INODE);
  	CHECK_FLAG_VALUE(EOFBLOCKS);
  	CHECK_FLAG_VALUE(RESERVED);
  }
  
  /* Used to pass group descriptor data when online resize is done */
  struct ext4_new_group_input {
  	__u32 group;		/* Group number for this data */
  	__u64 block_bitmap;	/* Absolute block number of block bitmap */
  	__u64 inode_bitmap;	/* Absolute block number of inode bitmap */
  	__u64 inode_table;	/* Absolute block number of inode table start */
  	__u32 blocks_count;	/* Total number of blocks in this group */
  	__u16 reserved_blocks;	/* Number of reserved blocks in this group */
  	__u16 unused;
  };
  
  #if defined(__KERNEL__) && defined(CONFIG_COMPAT)
  struct compat_ext4_new_group_input {
  	u32 group;
  	compat_u64 block_bitmap;
  	compat_u64 inode_bitmap;
  	compat_u64 inode_table;
  	u32 blocks_count;
  	u16 reserved_blocks;
  	u16 unused;
  };
  #endif
  
  /* The struct ext4_new_group_input in kernel space, with free_blocks_count */
  struct ext4_new_group_data {
  	__u32 group;
  	__u64 block_bitmap;
  	__u64 inode_bitmap;
  	__u64 inode_table;
  	__u32 blocks_count;
  	__u16 reserved_blocks;
  	__u16 unused;
  	__u32 free_blocks_count;
  };
  
  /*
   * Flags used by ext4_map_blocks()
   */
  	/* Allocate any needed blocks and/or convert an unitialized
  	   extent to be an initialized ext4 */
  #define EXT4_GET_BLOCKS_CREATE			0x0001
  	/* Request the creation of an unitialized extent */
  #define EXT4_GET_BLOCKS_UNINIT_EXT		0x0002
  #define EXT4_GET_BLOCKS_CREATE_UNINIT_EXT	(EXT4_GET_BLOCKS_UNINIT_EXT|\
  						 EXT4_GET_BLOCKS_CREATE)
  	/* Caller is from the delayed allocation writeout path,
  	   so set the magic i_delalloc_reserve_flag after taking the
  	   inode allocation semaphore for */
  #define EXT4_GET_BLOCKS_DELALLOC_RESERVE	0x0004
  	/* caller is from the direct IO path, request to creation of an
  	unitialized extents if not allocated, split the uninitialized
  	extent if blocks has been preallocated already*/
  #define EXT4_GET_BLOCKS_PRE_IO			0x0008
  #define EXT4_GET_BLOCKS_CONVERT			0x0010
  #define EXT4_GET_BLOCKS_IO_CREATE_EXT		(EXT4_GET_BLOCKS_PRE_IO|\
  					 EXT4_GET_BLOCKS_CREATE_UNINIT_EXT)
  	/* Convert extent to initialized after IO complete */
  #define EXT4_GET_BLOCKS_IO_CONVERT_EXT		(EXT4_GET_BLOCKS_CONVERT|\
  					 EXT4_GET_BLOCKS_CREATE_UNINIT_EXT)
  	/* Punch out blocks of an extent */
  #define EXT4_GET_BLOCKS_PUNCH_OUT_EXT		0x0020
  	/* Don't normalize allocation size (used for fallocate) */
  #define EXT4_GET_BLOCKS_NO_NORMALIZE		0x0040
  
  /*
   * Flags used by ext4_free_blocks
   */
  #define EXT4_FREE_BLOCKS_METADATA	0x0001
  #define EXT4_FREE_BLOCKS_FORGET		0x0002
  #define EXT4_FREE_BLOCKS_VALIDATED	0x0004
  #define EXT4_FREE_BLOCKS_NO_QUOT_UPDATE	0x0008
  
  /*
   * ioctl commands
   */
  #define	EXT4_IOC_GETFLAGS		FS_IOC_GETFLAGS
  #define	EXT4_IOC_SETFLAGS		FS_IOC_SETFLAGS
  #define	EXT4_IOC_GETVERSION		_IOR('f', 3, long)
  #define	EXT4_IOC_SETVERSION		_IOW('f', 4, long)
  #define	EXT4_IOC_GETVERSION_OLD		FS_IOC_GETVERSION
  #define	EXT4_IOC_SETVERSION_OLD		FS_IOC_SETVERSION
  #ifdef CONFIG_JBD2_DEBUG
  #define EXT4_IOC_WAIT_FOR_READONLY	_IOR('f', 99, long)
  #endif
  #define EXT4_IOC_GETRSVSZ		_IOR('f', 5, long)
  #define EXT4_IOC_SETRSVSZ		_IOW('f', 6, long)
  #define EXT4_IOC_GROUP_EXTEND		_IOW('f', 7, unsigned long)
  #define EXT4_IOC_GROUP_ADD		_IOW('f', 8, struct ext4_new_group_input)
  #define EXT4_IOC_MIGRATE		_IO('f', 9)
   /* note ioctl 10 reserved for an early version of the FIEMAP ioctl */
   /* note ioctl 11 reserved for filesystem-independent FIEMAP ioctl */
  #define EXT4_IOC_ALLOC_DA_BLKS		_IO('f', 12)
  #define EXT4_IOC_MOVE_EXT		_IOWR('f', 15, struct move_extent)
  
  #if defined(__KERNEL__) && defined(CONFIG_COMPAT)
  /*
   * ioctl commands in 32 bit emulation
   */
  #define EXT4_IOC32_GETFLAGS		FS_IOC32_GETFLAGS
  #define EXT4_IOC32_SETFLAGS		FS_IOC32_SETFLAGS
  #define EXT4_IOC32_GETVERSION		_IOR('f', 3, int)
  #define EXT4_IOC32_SETVERSION		_IOW('f', 4, int)
  #define EXT4_IOC32_GETRSVSZ		_IOR('f', 5, int)
  #define EXT4_IOC32_SETRSVSZ		_IOW('f', 6, int)
  #define EXT4_IOC32_GROUP_EXTEND		_IOW('f', 7, unsigned int)
  #define EXT4_IOC32_GROUP_ADD		_IOW('f', 8, struct compat_ext4_new_group_input)
  #ifdef CONFIG_JBD2_DEBUG
  #define EXT4_IOC32_WAIT_FOR_READONLY	_IOR('f', 99, int)
  #endif
  #define EXT4_IOC32_GETVERSION_OLD	FS_IOC32_GETVERSION
  #define EXT4_IOC32_SETVERSION_OLD	FS_IOC32_SETVERSION
  #endif
  
  /* Max physical block we can address w/o extents */
  #define EXT4_MAX_BLOCK_FILE_PHYS	0xFFFFFFFF
  
  /*
   * Structure of an inode on the disk
   */
  struct ext4_inode {
  	__le16	i_mode;		/* File mode */
  	__le16	i_uid;		/* Low 16 bits of Owner Uid */
  	__le32	i_size_lo;	/* Size in bytes */
  	__le32	i_atime;	/* Access time */
  	__le32	i_ctime;	/* Inode Change time */
  	__le32	i_mtime;	/* Modification time */
  	__le32	i_dtime;	/* Deletion Time */
  	__le16	i_gid;		/* Low 16 bits of Group Id */
  	__le16	i_links_count;	/* Links count */
  	__le32	i_blocks_lo;	/* Blocks count */
  	__le32	i_flags;	/* File flags */
  	union {
  		struct {
  			__le32  l_i_version;
  		} linux1;
  		struct {
  			__u32  h_i_translator;
  		} hurd1;
  		struct {
  			__u32  m_i_reserved1;
  		} masix1;
  	} osd1;				/* OS dependent 1 */
  	__le32	i_block[EXT4_N_BLOCKS];/* Pointers to blocks */
  	__le32	i_generation;	/* File version (for NFS) */
  	__le32	i_file_acl_lo;	/* File ACL */
  	__le32	i_size_high;
  	__le32	i_obso_faddr;	/* Obsoleted fragment address */
  	union {
  		struct {
  			__le16	l_i_blocks_high; /* were l_i_reserved1 */
  			__le16	l_i_file_acl_high;
  			__le16	l_i_uid_high;	/* these 2 fields */
  			__le16	l_i_gid_high;	/* were reserved2[0] */
  			__u32	l_i_reserved2;
  		} linux2;
  		struct {
  			__le16	h_i_reserved1;	/* Obsoleted fragment number/size which are removed in ext4 */
  			__u16	h_i_mode_high;
  			__u16	h_i_uid_high;
  			__u16	h_i_gid_high;
  			__u32	h_i_author;
  		} hurd2;
  		struct {
  			__le16	h_i_reserved1;	/* Obsoleted fragment number/size which are removed in ext4 */
  			__le16	m_i_file_acl_high;
  			__u32	m_i_reserved2[2];
  		} masix2;
  	} osd2;				/* OS dependent 2 */
  	__le16	i_extra_isize;
  	__le16	i_pad1;
  	__le32  i_ctime_extra;  /* extra Change time      (nsec << 2 | epoch) */
  	__le32  i_mtime_extra;  /* extra Modification time(nsec << 2 | epoch) */
  	__le32  i_atime_extra;  /* extra Access time      (nsec << 2 | epoch) */
  	__le32  i_crtime;       /* File Creation time */
  	__le32  i_crtime_extra; /* extra FileCreationtime (nsec << 2 | epoch) */
  	__le32  i_version_hi;	/* high 32 bits for 64-bit version */
  };
  
  struct move_extent {
  	__u32 reserved;		/* should be zero */
  	__u32 donor_fd;		/* donor file descriptor */
  	__u64 orig_start;	/* logical start offset in block for orig */
  	__u64 donor_start;	/* logical start offset in block for donor */
  	__u64 len;		/* block length to be moved */
  	__u64 moved_len;	/* moved block length */
  };
  
  #define EXT4_EPOCH_BITS 2
  #define EXT4_EPOCH_MASK ((1 << EXT4_EPOCH_BITS) - 1)
  #define EXT4_NSEC_MASK  (~0UL << EXT4_EPOCH_BITS)
  
  /*
   * Extended fields will fit into an inode if the filesystem was formatted
   * with large inodes (-I 256 or larger) and there are not currently any EAs
   * consuming all of the available space. For new inodes we always reserve
   * enough space for the kernel's known extended fields, but for inodes
   * created with an old kernel this might not have been the case. None of
   * the extended inode fields is critical for correct filesystem operation.
   * This macro checks if a certain field fits in the inode. Note that
   * inode-size = GOOD_OLD_INODE_SIZE + i_extra_isize
   */
  #define EXT4_FITS_IN_INODE(ext4_inode, einode, field)	\
  	((offsetof(typeof(*ext4_inode), field) +	\
  	  sizeof((ext4_inode)->field))			\
  	<= (EXT4_GOOD_OLD_INODE_SIZE +			\
  	    (einode)->i_extra_isize))			\
  
  static inline __le32 ext4_encode_extra_time(struct timespec *time)
  {
         return cpu_to_le32((sizeof(time->tv_sec) > 4 ?
  			   (time->tv_sec >> 32) & EXT4_EPOCH_MASK : 0) |
                            ((time->tv_nsec << EXT4_EPOCH_BITS) & EXT4_NSEC_MASK));
  }
  
  static inline void ext4_decode_extra_time(struct timespec *time, __le32 extra)
  {
         if (sizeof(time->tv_sec) > 4)
  	       time->tv_sec |= (__u64)(le32_to_cpu(extra) & EXT4_EPOCH_MASK)
  			       << 32;
         time->tv_nsec = (le32_to_cpu(extra) & EXT4_NSEC_MASK) >> EXT4_EPOCH_BITS;
  }
  
  #define EXT4_INODE_SET_XTIME(xtime, inode, raw_inode)			       \
  do {									       \
  	(raw_inode)->xtime = cpu_to_le32((inode)->xtime.tv_sec);	       \
  	if (EXT4_FITS_IN_INODE(raw_inode, EXT4_I(inode), xtime ## _extra))     \
  		(raw_inode)->xtime ## _extra =				       \
  				ext4_encode_extra_time(&(inode)->xtime);       \
  } while (0)
  
  #define EXT4_EINODE_SET_XTIME(xtime, einode, raw_inode)			       \
  do {									       \
  	if (EXT4_FITS_IN_INODE(raw_inode, einode, xtime))		       \
  		(raw_inode)->xtime = cpu_to_le32((einode)->xtime.tv_sec);      \
  	if (EXT4_FITS_IN_INODE(raw_inode, einode, xtime ## _extra))	       \
  		(raw_inode)->xtime ## _extra =				       \
  				ext4_encode_extra_time(&(einode)->xtime);      \
  } while (0)
  
  #define EXT4_INODE_GET_XTIME(xtime, inode, raw_inode)			       \
  do {									       \
  	(inode)->xtime.tv_sec = (signed)le32_to_cpu((raw_inode)->xtime);       \
  	if (EXT4_FITS_IN_INODE(raw_inode, EXT4_I(inode), xtime ## _extra))     \
  		ext4_decode_extra_time(&(inode)->xtime,			       \
  				       raw_inode->xtime ## _extra);	       \
  	else								       \
  		(inode)->xtime.tv_nsec = 0;				       \
  } while (0)
  
  #define EXT4_EINODE_GET_XTIME(xtime, einode, raw_inode)			       \
  do {									       \
  	if (EXT4_FITS_IN_INODE(raw_inode, einode, xtime))		       \
  		(einode)->xtime.tv_sec = 				       \
  			(signed)le32_to_cpu((raw_inode)->xtime);	       \
  	if (EXT4_FITS_IN_INODE(raw_inode, einode, xtime ## _extra))	       \
  		ext4_decode_extra_time(&(einode)->xtime,		       \
  				       raw_inode->xtime ## _extra);	       \
  	else								       \
  		(einode)->xtime.tv_nsec = 0;				       \
  } while (0)
  
  #define i_disk_version osd1.linux1.l_i_version
  
  #if defined(__KERNEL__) || defined(__linux__)
  #define i_reserved1	osd1.linux1.l_i_reserved1
  #define i_file_acl_high	osd2.linux2.l_i_file_acl_high
  #define i_blocks_high	osd2.linux2.l_i_blocks_high
  #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
  
  #elif defined(__GNU__)
  
  #define i_translator	osd1.hurd1.h_i_translator
  #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
  
  #elif defined(__masix__)
  
  #define i_reserved1	osd1.masix1.m_i_reserved1
  #define i_file_acl_high	osd2.masix2.m_i_file_acl_high
  #define i_reserved2	osd2.masix2.m_i_reserved2
  
  #endif /* defined(__KERNEL__) || defined(__linux__) */
  
  /*
   * storage for cached extent
   * If ec_len == 0, then the cache is invalid.
   * If ec_start == 0, then the cache represents a gap (null mapping)
   */
  struct ext4_ext_cache {
  	ext4_fsblk_t	ec_start;
  	ext4_lblk_t	ec_block;
  	__u32		ec_len; /* must be 32bit to return holes */
  };
  
  /*
   * fourth extended file system inode data in memory
   */
  struct ext4_inode_info {
  	__le32	i_data[15];	/* unconverted */
  	__u32	i_dtime;
  	ext4_fsblk_t	i_file_acl;
  
  	/*
  	 * i_block_group is the number of the block group which contains
  	 * this file's inode.  Constant across the lifetime of the inode,
  	 * it is ued for making block allocation decisions - we try to
  	 * place a file's data blocks near its inode block, and new inodes
  	 * near to their parent directory's inode.
  	 */
  	ext4_group_t	i_block_group;
  	ext4_lblk_t	i_dir_start_lookup;
  #if (BITS_PER_LONG < 64)
  	unsigned long	i_state_flags;		/* Dynamic state flags */
  #endif
  	unsigned long	i_flags;
  
  #ifdef CONFIG_EXT4_FS_XATTR
  	/*
  	 * Extended attributes can be read independently of the main file
  	 * data. Taking i_mutex even when reading would cause contention
  	 * between readers of EAs and writers of regular file data, so
  	 * instead we synchronize on xattr_sem when reading or changing
  	 * EAs.
  	 */
  	struct rw_semaphore xattr_sem;
  #endif
  
  	struct list_head i_orphan;	/* unlinked but open inodes */
  
  	/*
  	 * i_disksize keeps track of what the inode size is ON DISK, not
  	 * in memory.  During truncate, i_size is set to the new size by
  	 * the VFS prior to calling ext4_truncate(), but the filesystem won't
  	 * set i_disksize to 0 until the truncate is actually under way.
  	 *
  	 * The intent is that i_disksize always represents the blocks which
  	 * are used by this file.  This allows recovery to restart truncate
  	 * on orphans if we crash during truncate.  We actually write i_disksize
  	 * into the on-disk inode when writing inodes out, instead of i_size.
  	 *
  	 * The only time when i_disksize and i_size may be different is when
  	 * a truncate is in progress.  The only things which change i_disksize
  	 * are ext4_get_block (growth) and ext4_truncate (shrinkth).
  	 */
  	loff_t	i_disksize;
  
  	/*
  	 * i_data_sem is for serialising ext4_truncate() against
  	 * ext4_getblock().  In the 2.4 ext2 design, great chunks of inode's
  	 * data tree are chopped off during truncate. We can't do that in
  	 * ext4 because whenever we perform intermediate commits during
  	 * truncate, the inode and all the metadata blocks *must* be in a
  	 * consistent state which allows truncation of the orphans to restart
  	 * during recovery.  Hence we must fix the get_block-vs-truncate race
  	 * by other means, so we have i_data_sem.
  	 */
  	struct rw_semaphore i_data_sem;
  	struct inode vfs_inode;
  	struct jbd2_inode *jinode;
  
  	struct ext4_ext_cache i_cached_extent;
  	/*
  	 * File creation time. Its function is same as that of
  	 * struct timespec i_{a,c,m}time in the generic inode.
  	 */
  	struct timespec i_crtime;
  
  	/* mballoc */
  	struct list_head i_prealloc_list;
  	spinlock_t i_prealloc_lock;
  
  	/* ialloc */
  	ext4_group_t	i_last_alloc_group;
  
  	/* allocation reservation info for delalloc */
  	unsigned int i_reserved_data_blocks;
  	unsigned int i_reserved_meta_blocks;
  	unsigned int i_allocated_meta_blocks;
  	ext4_lblk_t i_da_metadata_calc_last_lblock;
  	int i_da_metadata_calc_len;
  
  	/* on-disk additional length */
  	__u16 i_extra_isize;
  
  #ifdef CONFIG_QUOTA
  	/* quota space reservation, managed internally by quota code */
  	qsize_t i_reserved_quota;
  #endif
  
  	/* completed IOs that might need unwritten extents handling */
  	struct list_head i_completed_io_list;
  	spinlock_t i_completed_io_lock;
  	atomic_t i_ioend_count;	/* Number of outstanding io_end structs */
  	/* current io_end structure for async DIO write*/
  	ext4_io_end_t *cur_aio_dio;
  	atomic_t i_aiodio_unwritten; /* Nr. of inflight conversions pending */
  
  	spinlock_t i_block_reservation_lock;
  
  	/*
  	 * Transactions that contain inode's metadata needed to complete
  	 * fsync and fdatasync, respectively.
  	 */
  	tid_t i_sync_tid;
  	tid_t i_datasync_tid;
  };
  
  /*
   * File system states
   */
  #define	EXT4_VALID_FS			0x0001	/* Unmounted cleanly */
  #define	EXT4_ERROR_FS			0x0002	/* Errors detected */
  #define	EXT4_ORPHAN_FS			0x0004	/* Orphans being recovered */
  
  /*
   * Misc. filesystem flags
   */
  #define EXT2_FLAGS_SIGNED_HASH		0x0001  /* Signed dirhash in use */
  #define EXT2_FLAGS_UNSIGNED_HASH	0x0002  /* Unsigned dirhash in use */
  #define EXT2_FLAGS_TEST_FILESYS		0x0004	/* to test development code */
  
  /*
   * Mount flags
   */
  #define EXT4_MOUNT_OLDALLOC		0x00002  /* Don't use the new Orlov allocator */
  #define EXT4_MOUNT_GRPID		0x00004	/* Create files with directory's group */
  #define EXT4_MOUNT_DEBUG		0x00008	/* Some debugging messages */
  #define EXT4_MOUNT_ERRORS_CONT		0x00010	/* Continue on errors */
  #define EXT4_MOUNT_ERRORS_RO		0x00020	/* Remount fs ro on errors */
  #define EXT4_MOUNT_ERRORS_PANIC		0x00040	/* Panic on errors */
  #define EXT4_MOUNT_MINIX_DF		0x00080	/* Mimics the Minix statfs */
  #define EXT4_MOUNT_NOLOAD		0x00100	/* Don't use existing journal*/
  #define EXT4_MOUNT_DATA_FLAGS		0x00C00	/* Mode for data writes: */
  #define EXT4_MOUNT_JOURNAL_DATA		0x00400	/* Write data to journal */
  #define EXT4_MOUNT_ORDERED_DATA		0x00800	/* Flush data before commit */
  #define EXT4_MOUNT_WRITEBACK_DATA	0x00C00	/* No data ordering */
  #define EXT4_MOUNT_UPDATE_JOURNAL	0x01000	/* Update the journal format */
  #define EXT4_MOUNT_NO_UID32		0x02000  /* Disable 32-bit UIDs */
  #define EXT4_MOUNT_XATTR_USER		0x04000	/* Extended user attributes */
  #define EXT4_MOUNT_POSIX_ACL		0x08000	/* POSIX Access Control Lists */
  #define EXT4_MOUNT_NO_AUTO_DA_ALLOC	0x10000	/* No auto delalloc mapping */
  #define EXT4_MOUNT_BARRIER		0x20000 /* Use block barriers */
  #define EXT4_MOUNT_QUOTA		0x80000 /* Some quota option set */
  #define EXT4_MOUNT_USRQUOTA		0x100000 /* "old" user quota */
  #define EXT4_MOUNT_GRPQUOTA		0x200000 /* "old" group quota */
  #define EXT4_MOUNT_DIOREAD_NOLOCK	0x400000 /* Enable support for dio read nolocking */
  #define EXT4_MOUNT_JOURNAL_CHECKSUM	0x800000 /* Journal checksums */
  #define EXT4_MOUNT_JOURNAL_ASYNC_COMMIT	0x1000000 /* Journal Async Commit */
  #define EXT4_MOUNT_I_VERSION            0x2000000 /* i_version support */
  #define EXT4_MOUNT_MBLK_IO_SUBMIT	0x4000000 /* multi-block io submits */
  #define EXT4_MOUNT_DELALLOC		0x8000000 /* Delalloc support */
  #define EXT4_MOUNT_DATA_ERR_ABORT	0x10000000 /* Abort on file data write */
  #define EXT4_MOUNT_BLOCK_VALIDITY	0x20000000 /* Block validity checking */
  #define EXT4_MOUNT_DISCARD		0x40000000 /* Issue DISCARD requests */
  #define EXT4_MOUNT_INIT_INODE_TABLE	0x80000000 /* Initialize uninitialized itables */
  
  #define clear_opt(sb, opt)		EXT4_SB(sb)->s_mount_opt &= \
  						~EXT4_MOUNT_##opt
  #define set_opt(sb, opt)		EXT4_SB(sb)->s_mount_opt |= \
  						EXT4_MOUNT_##opt
  #define test_opt(sb, opt)		(EXT4_SB(sb)->s_mount_opt & \
  					 EXT4_MOUNT_##opt)
  
  #define clear_opt2(sb, opt)		EXT4_SB(sb)->s_mount_opt2 &= \
  						~EXT4_MOUNT2_##opt
  #define set_opt2(sb, opt)		EXT4_SB(sb)->s_mount_opt2 |= \
  						EXT4_MOUNT2_##opt
  #define test_opt2(sb, opt)		(EXT4_SB(sb)->s_mount_opt2 & \
  					 EXT4_MOUNT2_##opt)
  
  #define ext4_set_bit			__test_and_set_bit_le
  #define ext4_set_bit_atomic		ext2_set_bit_atomic
  #define ext4_clear_bit			__test_and_clear_bit_le
  #define ext4_clear_bit_atomic		ext2_clear_bit_atomic
  #define ext4_test_bit			test_bit_le
  #define ext4_find_first_zero_bit	find_first_zero_bit_le
  #define ext4_find_next_zero_bit		find_next_zero_bit_le
  #define ext4_find_next_bit		find_next_bit_le
  
  /*
   * Maximal mount counts between two filesystem checks
   */
  #define EXT4_DFL_MAX_MNT_COUNT		20	/* Allow 20 mounts */
  #define EXT4_DFL_CHECKINTERVAL		0	/* Don't use interval check */
  
  /*
   * Behaviour when detecting errors
   */
  #define EXT4_ERRORS_CONTINUE		1	/* Continue execution */
  #define EXT4_ERRORS_RO			2	/* Remount fs read-only */
  #define EXT4_ERRORS_PANIC		3	/* Panic */
  #define EXT4_ERRORS_DEFAULT		EXT4_ERRORS_CONTINUE
  
  /*
   * Structure of the super block
   */
  struct ext4_super_block {
  /*00*/	__le32	s_inodes_count;		/* Inodes count */
  	__le32	s_blocks_count_lo;	/* Blocks count */
  	__le32	s_r_blocks_count_lo;	/* Reserved blocks count */
  	__le32	s_free_blocks_count_lo;	/* Free blocks count */
  /*10*/	__le32	s_free_inodes_count;	/* Free inodes count */
  	__le32	s_first_data_block;	/* First Data Block */
  	__le32	s_log_block_size;	/* Block size */
  	__le32	s_obso_log_frag_size;	/* Obsoleted fragment size */
  /*20*/	__le32	s_blocks_per_group;	/* # Blocks per group */
  	__le32	s_obso_frags_per_group;	/* Obsoleted fragments per group */
  	__le32	s_inodes_per_group;	/* # Inodes per group */
  	__le32	s_mtime;		/* Mount time */
  /*30*/	__le32	s_wtime;		/* Write time */
  	__le16	s_mnt_count;		/* Mount count */
  	__le16	s_max_mnt_count;	/* Maximal mount count */
  	__le16	s_magic;		/* Magic signature */
  	__le16	s_state;		/* File system state */
  	__le16	s_errors;		/* Behaviour when detecting errors */
  	__le16	s_minor_rev_level;	/* minor revision level */
  /*40*/	__le32	s_lastcheck;		/* time of last check */
  	__le32	s_checkinterval;	/* max. time between checks */
  	__le32	s_creator_os;		/* OS */
  	__le32	s_rev_level;		/* Revision level */
  /*50*/	__le16	s_def_resuid;		/* Default uid for reserved blocks */
  	__le16	s_def_resgid;		/* Default gid for reserved blocks */
  	/*
  	 * These fields are for EXT4_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...
  	 */
  	__le32	s_first_ino;		/* First non-reserved inode */
  	__le16  s_inode_size;		/* size of inode structure */
  	__le16	s_block_group_nr;	/* block group # of this superblock */
  	__le32	s_feature_compat;	/* compatible feature set */
  /*60*/	__le32	s_feature_incompat;	/* incompatible feature set */
  	__le32	s_feature_ro_compat;	/* readonly-compatible feature set */
  /*68*/	__u8	s_uuid[16];		/* 128-bit uuid for volume */
  /*78*/	char	s_volume_name[16];	/* volume name */
  /*88*/	char	s_last_mounted[64];	/* directory where last mounted */
  /*C8*/	__le32	s_algorithm_usage_bitmap; /* For compression */
  	/*
  	 * Performance hints.  Directory preallocation should only
  	 * happen if the EXT4_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 */
  	__le16	s_reserved_gdt_blocks;	/* Per group desc for online growth */
  	/*
  	 * Journaling support valid if EXT4_FEATURE_COMPAT_HAS_JOURNAL set.
  	 */
  /*D0*/	__u8	s_journal_uuid[16];	/* uuid of journal superblock */
  /*E0*/	__le32	s_journal_inum;		/* inode number of journal file */
  	__le32	s_journal_dev;		/* device number of journal file */
  	__le32	s_last_orphan;		/* start of list of inodes to delete */
  	__le32	s_hash_seed[4];		/* HTREE hash seed */
  	__u8	s_def_hash_version;	/* Default hash version to use */
  	__u8	s_jnl_backup_type;
  	__le16  s_desc_size;		/* size of group descriptor */
  /*100*/	__le32	s_default_mount_opts;
  	__le32	s_first_meta_bg;	/* First metablock block group */
  	__le32	s_mkfs_time;		/* When the filesystem was created */
  	__le32	s_jnl_blocks[17];	/* Backup of the journal inode */
  	/* 64bit support valid if EXT4_FEATURE_COMPAT_64BIT */
  /*150*/	__le32	s_blocks_count_hi;	/* Blocks count */
  	__le32	s_r_blocks_count_hi;	/* Reserved blocks count */
  	__le32	s_free_blocks_count_hi;	/* Free blocks count */
  	__le16	s_min_extra_isize;	/* All inodes have at least # bytes */
  	__le16	s_want_extra_isize; 	/* New inodes should reserve # bytes */
  	__le32	s_flags;		/* Miscellaneous flags */
  	__le16  s_raid_stride;		/* RAID stride */
  	__le16  s_mmp_update_interval;  /* # seconds to wait in MMP checking */
  	__le64  s_mmp_block;            /* Block for multi-mount protection */
  	__le32  s_raid_stripe_width;    /* blocks on all data disks (N*stride)*/
  	__u8	s_log_groups_per_flex;  /* FLEX_BG group size */
  	__u8	s_reserved_char_pad;
  	__le16  s_reserved_pad;
  	__le64	s_kbytes_written;	/* nr of lifetime kilobytes written */
  	__le32	s_snapshot_inum;	/* Inode number of active snapshot */
  	__le32	s_snapshot_id;		/* sequential ID of active snapshot */
  	__le64	s_snapshot_r_blocks_count; /* reserved blocks for active
  					      snapshot's future use */
  	__le32	s_snapshot_list;	/* inode number of the head of the
  					   on-disk snapshot list */
  #define EXT4_S_ERR_START offsetof(struct ext4_super_block, s_error_count)
  	__le32	s_error_count;		/* number of fs errors */
  	__le32	s_first_error_time;	/* first time an error happened */
  	__le32	s_first_error_ino;	/* inode involved in first error */
  	__le64	s_first_error_block;	/* block involved of first error */
  	__u8	s_first_error_func[32];	/* function where the error happened */
  	__le32	s_first_error_line;	/* line number where error happened */
  	__le32	s_last_error_time;	/* most recent time of an error */
  	__le32	s_last_error_ino;	/* inode involved in last error */
  	__le32	s_last_error_line;	/* line number where error happened */
  	__le64	s_last_error_block;	/* block involved of last error */
  	__u8	s_last_error_func[32];	/* function where the error happened */
  #define EXT4_S_ERR_END offsetof(struct ext4_super_block, s_mount_opts)
  	__u8	s_mount_opts[64];
  	__le32	s_reserved[112];        /* Padding to the end of the block */
  };
  
  #define EXT4_S_ERR_LEN (EXT4_S_ERR_END - EXT4_S_ERR_START)
  
  #ifdef __KERNEL__
  
  /*
   * run-time mount flags
   */
  #define EXT4_MF_MNTDIR_SAMPLED	0x0001
  #define EXT4_MF_FS_ABORTED	0x0002	/* Fatal error detected */
  
  /*
   * fourth extended-fs super-block data in memory
   */
  struct ext4_sb_info {
  	unsigned long s_desc_size;	/* Size of a group descriptor in bytes */
  	unsigned long s_inodes_per_block;/* Number of inodes per block */
  	unsigned long s_blocks_per_group;/* Number of blocks in a group */
  	unsigned long s_inodes_per_group;/* Number of inodes in a group */
  	unsigned long s_itb_per_group;	/* Number of inode table blocks per group */
  	unsigned long s_gdb_count;	/* Number of group descriptor blocks */
  	unsigned long s_desc_per_block;	/* Number of group descriptors per block */
  	ext4_group_t s_groups_count;	/* Number of groups in the fs */
  	ext4_group_t s_blockfile_groups;/* Groups acceptable for non-extent files */
  	unsigned long s_overhead_last;  /* Last calculated overhead */
  	unsigned long s_blocks_last;    /* Last seen block count */
  	loff_t s_bitmap_maxbytes;	/* max bytes for bitmap files */
  	struct buffer_head * s_sbh;	/* Buffer containing the super block */
  	struct ext4_super_block *s_es;	/* Pointer to the super block in the buffer */
  	struct buffer_head **s_group_desc;
  	unsigned int s_mount_opt;
  	unsigned int s_mount_opt2;
  	unsigned int s_mount_flags;
  	ext4_fsblk_t s_sb_block;
  	uid_t s_resuid;
  	gid_t s_resgid;
  	unsigned short s_mount_state;
  	unsigned short s_pad;
  	int s_addr_per_block_bits;
  	int s_desc_per_block_bits;
  	int s_inode_size;
  	int s_first_ino;
  	unsigned int s_inode_readahead_blks;
  	unsigned int s_inode_goal;
  	spinlock_t s_next_gen_lock;
  	u32 s_next_generation;
  	u32 s_hash_seed[4];
  	int s_def_hash_version;
  	int s_hash_unsigned;	/* 3 if hash should be signed, 0 if not */
  	struct percpu_counter s_freeblocks_counter;
  	struct percpu_counter s_freeinodes_counter;
  	struct percpu_counter s_dirs_counter;
  	struct percpu_counter s_dirtyblocks_counter;
  	struct blockgroup_lock *s_blockgroup_lock;
  	struct proc_dir_entry *s_proc;
  	struct kobject s_kobj;
  	struct completion s_kobj_unregister;
  
  	/* Journaling */
  	struct journal_s *s_journal;
  	struct list_head s_orphan;
  	struct mutex s_orphan_lock;
  	struct mutex s_resize_lock;
  	unsigned long s_commit_interval;
  	u32 s_max_batch_time;
  	u32 s_min_batch_time;
  	struct block_device *journal_bdev;
  #ifdef CONFIG_JBD2_DEBUG
  	struct timer_list turn_ro_timer;	/* For turning read-only (crash simulation) */
  	wait_queue_head_t ro_wait_queue;	/* For people waiting for the fs to go read-only */
  #endif
  #ifdef CONFIG_QUOTA
  	char *s_qf_names[MAXQUOTAS];		/* Names of quota files with journalled quota */
  	int s_jquota_fmt;			/* Format of quota to use */
  #endif
  	unsigned int s_want_extra_isize; /* New inodes should reserve # bytes */
  	struct rb_root system_blks;
  
  #ifdef EXTENTS_STATS
  	/* ext4 extents stats */
  	unsigned long s_ext_min;
  	unsigned long s_ext_max;
  	unsigned long s_depth_max;
  	spinlock_t s_ext_stats_lock;
  	unsigned long s_ext_blocks;
  	unsigned long s_ext_extents;
  #endif
  	/* ext4 extent cache stats */
  	unsigned long extent_cache_hits;
  	unsigned long extent_cache_misses;
  
  	/* for buddy allocator */
  	struct ext4_group_info ***s_group_info;
  	struct inode *s_buddy_cache;
  	spinlock_t s_md_lock;
  	unsigned short *s_mb_offsets;
  	unsigned int *s_mb_maxs;
  
  	/* tunables */
  	unsigned long s_stripe;
  	unsigned int s_mb_stream_request;
  	unsigned int s_mb_max_to_scan;
  	unsigned int s_mb_min_to_scan;
  	unsigned int s_mb_stats;
  	unsigned int s_mb_order2_reqs;
  	unsigned int s_mb_group_prealloc;
  	unsigned int s_max_writeback_mb_bump;
  	/* where last allocation was done - for stream allocation */
  	unsigned long s_mb_last_group;
  	unsigned long s_mb_last_start;
  
  	/* stats for buddy allocator */
  	atomic_t s_bal_reqs;	/* number of reqs with len > 1 */
  	atomic_t s_bal_success;	/* we found long enough chunks */
  	atomic_t s_bal_allocated;	/* in blocks */
  	atomic_t s_bal_ex_scanned;	/* total extents scanned */
  	atomic_t s_bal_goals;	/* goal hits */
  	atomic_t s_bal_breaks;	/* too long searches */
  	atomic_t s_bal_2orders;	/* 2^order hits */
  	spinlock_t s_bal_lock;
  	unsigned long s_mb_buddies_generated;
  	unsigned long long s_mb_generation_time;
  	atomic_t s_mb_lost_chunks;
  	atomic_t s_mb_preallocated;
  	atomic_t s_mb_discarded;
  	atomic_t s_lock_busy;
  
  	/* locality groups */
  	struct ext4_locality_group __percpu *s_locality_groups;
  
  	/* for write statistics */
  	unsigned long s_sectors_written_start;
  	u64 s_kbytes_written;
  
  	unsigned int s_log_groups_per_flex;
  	struct flex_groups *s_flex_groups;
  
  	/* workqueue for dio unwritten */
  	struct workqueue_struct *dio_unwritten_wq;
  
  	/* timer for periodic error stats printing */
  	struct timer_list s_err_report;
  
  	/* Lazy inode table initialization info */
  	struct ext4_li_request *s_li_request;
  	/* Wait multiplier for lazy initialization thread */
  	unsigned int s_li_wait_mult;
  
  	/* Kernel thread for multiple mount protection */
  	struct task_struct *s_mmp_tsk;
  };
  
  static inline struct ext4_sb_info *EXT4_SB(struct super_block *sb)
  {
  	return sb->s_fs_info;
  }
  static inline struct ext4_inode_info *EXT4_I(struct inode *inode)
  {
  	return container_of(inode, struct ext4_inode_info, vfs_inode);
  }
  
  static inline struct timespec ext4_current_time(struct inode *inode)
  {
  	return (inode->i_sb->s_time_gran < NSEC_PER_SEC) ?
  		current_fs_time(inode->i_sb) : CURRENT_TIME_SEC;
  }
  
  static inline int ext4_valid_inum(struct super_block *sb, unsigned long ino)
  {
  	return ino == EXT4_ROOT_INO ||
  		ino == EXT4_JOURNAL_INO ||
  		ino == EXT4_RESIZE_INO ||
  		(ino >= EXT4_FIRST_INO(sb) &&
  		 ino <= le32_to_cpu(EXT4_SB(sb)->s_es->s_inodes_count));
  }
  
  /*
   * Inode dynamic state flags
   */
  enum {
  	EXT4_STATE_JDATA,		/* journaled data exists */
  	EXT4_STATE_NEW,			/* inode is newly created */
  	EXT4_STATE_XATTR,		/* has in-inode xattrs */
  	EXT4_STATE_NO_EXPAND,		/* No space for expansion */
  	EXT4_STATE_DA_ALLOC_CLOSE,	/* Alloc DA blks on close */
  	EXT4_STATE_EXT_MIGRATE,		/* Inode is migrating */
  	EXT4_STATE_DIO_UNWRITTEN,	/* need convert on dio done*/
  	EXT4_STATE_NEWENTRY,		/* File just added to dir */
  	EXT4_STATE_DELALLOC_RESERVED,	/* blks already reserved for delalloc */
  };
  
  #define EXT4_INODE_BIT_FNS(name, field, offset)				\
  static inline int ext4_test_inode_##name(struct inode *inode, int bit)	\
  {									\
  	return test_bit(bit + (offset), &EXT4_I(inode)->i_##field);	\
  }									\
  static inline void ext4_set_inode_##name(struct inode *inode, int bit)	\
  {									\
  	set_bit(bit + (offset), &EXT4_I(inode)->i_##field);		\
  }									\
  static inline void ext4_clear_inode_##name(struct inode *inode, int bit) \
  {									\
  	clear_bit(bit + (offset), &EXT4_I(inode)->i_##field);		\
  }
  
  EXT4_INODE_BIT_FNS(flag, flags, 0)
  #if (BITS_PER_LONG < 64)
  EXT4_INODE_BIT_FNS(state, state_flags, 0)
  
  static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
  {
  	(ei)->i_state_flags = 0;
  }
  #else
  EXT4_INODE_BIT_FNS(state, flags, 32)
  
  static inline void ext4_clear_state_flags(struct ext4_inode_info *ei)
  {
  	/* We depend on the fact that callers will set i_flags */
  }
  #endif
  #else
  /* Assume that user mode programs are passing in an ext4fs superblock, not
   * a kernel struct super_block.  This will allow us to call the feature-test
   * macros from user land. */
  #define EXT4_SB(sb)	(sb)
  #endif
  
  #define NEXT_ORPHAN(inode) EXT4_I(inode)->i_dtime
  
  /*
   * Codes for operating systems
   */
  #define EXT4_OS_LINUX		0
  #define EXT4_OS_HURD		1
  #define EXT4_OS_MASIX		2
  #define EXT4_OS_FREEBSD		3
  #define EXT4_OS_LITES		4
  
  /*
   * Revision levels
   */
  #define EXT4_GOOD_OLD_REV	0	/* The good old (original) format */
  #define EXT4_DYNAMIC_REV	1	/* V2 format w/ dynamic inode sizes */
  
  #define EXT4_CURRENT_REV	EXT4_GOOD_OLD_REV
  #define EXT4_MAX_SUPP_REV	EXT4_DYNAMIC_REV
  
  #define EXT4_GOOD_OLD_INODE_SIZE 128
  
  /*
   * Feature set definitions
   */
  
  #define EXT4_HAS_COMPAT_FEATURE(sb,mask)			\
  	((EXT4_SB(sb)->s_es->s_feature_compat & cpu_to_le32(mask)) != 0)
  #define EXT4_HAS_RO_COMPAT_FEATURE(sb,mask)			\
  	((EXT4_SB(sb)->s_es->s_feature_ro_compat & cpu_to_le32(mask)) != 0)
  #define EXT4_HAS_INCOMPAT_FEATURE(sb,mask)			\
  	((EXT4_SB(sb)->s_es->s_feature_incompat & cpu_to_le32(mask)) != 0)
  #define EXT4_SET_COMPAT_FEATURE(sb,mask)			\
  	EXT4_SB(sb)->s_es->s_feature_compat |= cpu_to_le32(mask)
  #define EXT4_SET_RO_COMPAT_FEATURE(sb,mask)			\
  	EXT4_SB(sb)->s_es->s_feature_ro_compat |= cpu_to_le32(mask)
  #define EXT4_SET_INCOMPAT_FEATURE(sb,mask)			\
  	EXT4_SB(sb)->s_es->s_feature_incompat |= cpu_to_le32(mask)
  #define EXT4_CLEAR_COMPAT_FEATURE(sb,mask)			\
  	EXT4_SB(sb)->s_es->s_feature_compat &= ~cpu_to_le32(mask)
  #define EXT4_CLEAR_RO_COMPAT_FEATURE(sb,mask)			\
  	EXT4_SB(sb)->s_es->s_feature_ro_compat &= ~cpu_to_le32(mask)
  #define EXT4_CLEAR_INCOMPAT_FEATURE(sb,mask)			\
  	EXT4_SB(sb)->s_es->s_feature_incompat &= ~cpu_to_le32(mask)
  
  #define EXT4_FEATURE_COMPAT_DIR_PREALLOC	0x0001
  #define EXT4_FEATURE_COMPAT_IMAGIC_INODES	0x0002
  #define EXT4_FEATURE_COMPAT_HAS_JOURNAL		0x0004
  #define EXT4_FEATURE_COMPAT_EXT_ATTR		0x0008
  #define EXT4_FEATURE_COMPAT_RESIZE_INODE	0x0010
  #define EXT4_FEATURE_COMPAT_DIR_INDEX		0x0020
  
  #define EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER	0x0001
  #define EXT4_FEATURE_RO_COMPAT_LARGE_FILE	0x0002
  #define EXT4_FEATURE_RO_COMPAT_BTREE_DIR	0x0004
  #define EXT4_FEATURE_RO_COMPAT_HUGE_FILE        0x0008
  #define EXT4_FEATURE_RO_COMPAT_GDT_CSUM		0x0010
  #define EXT4_FEATURE_RO_COMPAT_DIR_NLINK	0x0020
  #define EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE	0x0040
  #define EXT4_FEATURE_RO_COMPAT_QUOTA		0x0100
  
  #define EXT4_FEATURE_INCOMPAT_COMPRESSION	0x0001
  #define EXT4_FEATURE_INCOMPAT_FILETYPE		0x0002
  #define EXT4_FEATURE_INCOMPAT_RECOVER		0x0004 /* Needs recovery */
  #define EXT4_FEATURE_INCOMPAT_JOURNAL_DEV	0x0008 /* Journal device */
  #define EXT4_FEATURE_INCOMPAT_META_BG		0x0010
  #define EXT4_FEATURE_INCOMPAT_EXTENTS		0x0040 /* extents support */
  #define EXT4_FEATURE_INCOMPAT_64BIT		0x0080
  #define EXT4_FEATURE_INCOMPAT_MMP               0x0100
  #define EXT4_FEATURE_INCOMPAT_FLEX_BG		0x0200
  #define EXT4_FEATURE_INCOMPAT_EA_INODE		0x0400 /* EA in inode */
  #define EXT4_FEATURE_INCOMPAT_DIRDATA		0x1000 /* data in dirent */
  
  #define EXT2_FEATURE_COMPAT_SUPP	EXT4_FEATURE_COMPAT_EXT_ATTR
  #define EXT2_FEATURE_INCOMPAT_SUPP	(EXT4_FEATURE_INCOMPAT_FILETYPE| \
  					 EXT4_FEATURE_INCOMPAT_META_BG)
  #define EXT2_FEATURE_RO_COMPAT_SUPP	(EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER| \
  					 EXT4_FEATURE_RO_COMPAT_LARGE_FILE| \
  					 EXT4_FEATURE_RO_COMPAT_BTREE_DIR)
  
  #define EXT3_FEATURE_COMPAT_SUPP	EXT4_FEATURE_COMPAT_EXT_ATTR
  #define EXT3_FEATURE_INCOMPAT_SUPP	(EXT4_FEATURE_INCOMPAT_FILETYPE| \
  					 EXT4_FEATURE_INCOMPAT_RECOVER| \
  					 EXT4_FEATURE_INCOMPAT_META_BG)
  #define EXT3_FEATURE_RO_COMPAT_SUPP	(EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER| \
  					 EXT4_FEATURE_RO_COMPAT_LARGE_FILE| \
  					 EXT4_FEATURE_RO_COMPAT_BTREE_DIR)
  
  #define EXT4_FEATURE_COMPAT_SUPP	EXT2_FEATURE_COMPAT_EXT_ATTR
  #define EXT4_FEATURE_INCOMPAT_SUPP	(EXT4_FEATURE_INCOMPAT_FILETYPE| \
  					 EXT4_FEATURE_INCOMPAT_RECOVER| \
  					 EXT4_FEATURE_INCOMPAT_META_BG| \
  					 EXT4_FEATURE_INCOMPAT_EXTENTS| \
  					 EXT4_FEATURE_INCOMPAT_64BIT| \
  					 EXT4_FEATURE_INCOMPAT_FLEX_BG| \
  					 EXT4_FEATURE_INCOMPAT_MMP)
  #define EXT4_FEATURE_RO_COMPAT_SUPP	(EXT4_FEATURE_RO_COMPAT_SPARSE_SUPER| \
  					 EXT4_FEATURE_RO_COMPAT_LARGE_FILE| \
  					 EXT4_FEATURE_RO_COMPAT_GDT_CSUM| \
  					 EXT4_FEATURE_RO_COMPAT_DIR_NLINK | \
  					 EXT4_FEATURE_RO_COMPAT_EXTRA_ISIZE | \
  					 EXT4_FEATURE_RO_COMPAT_BTREE_DIR |\
  					 EXT4_FEATURE_RO_COMPAT_HUGE_FILE)
  
  /*
   * Default values for user and/or group using reserved blocks
   */
  #define	EXT4_DEF_RESUID		0
  #define	EXT4_DEF_RESGID		0
  
  #define EXT4_DEF_INODE_READAHEAD_BLKS	32
  
  /*
   * Default mount options
   */
  #define EXT4_DEFM_DEBUG		0x0001
  #define EXT4_DEFM_BSDGROUPS	0x0002
  #define EXT4_DEFM_XATTR_USER	0x0004
  #define EXT4_DEFM_ACL		0x0008
  #define EXT4_DEFM_UID16		0x0010
  #define EXT4_DEFM_JMODE		0x0060
  #define EXT4_DEFM_JMODE_DATA	0x0020
  #define EXT4_DEFM_JMODE_ORDERED	0x0040
  #define EXT4_DEFM_JMODE_WBACK	0x0060
  #define EXT4_DEFM_NOBARRIER	0x0100
  #define EXT4_DEFM_BLOCK_VALIDITY 0x0200
  #define EXT4_DEFM_DISCARD	0x0400
  #define EXT4_DEFM_NODELALLOC	0x0800
  
  /*
   * Default journal batch times
   */
  #define EXT4_DEF_MIN_BATCH_TIME	0
  #define EXT4_DEF_MAX_BATCH_TIME	15000 /* 15ms */
  
  /*
   * Minimum number of groups in a flexgroup before we separate out
   * directories into the first block group of a flexgroup
   */
  #define EXT4_FLEX_SIZE_DIR_ALLOC_SCHEME	4
  
  /*
   * Structure of a directory entry
   */
  #define EXT4_NAME_LEN 255
  
  struct ext4_dir_entry {
  	__le32	inode;			/* Inode number */
  	__le16	rec_len;		/* Directory entry length */
  	__le16	name_len;		/* Name length */
  	char	name[EXT4_NAME_LEN];	/* File name */
  };
  
  /*
   * The new version of the directory entry.  Since EXT4 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 ext4_dir_entry_2 {
  	__le32	inode;			/* Inode number */
  	__le16	rec_len;		/* Directory entry length */
  	__u8	name_len;		/* Name length */
  	__u8	file_type;
  	char	name[EXT4_NAME_LEN];	/* File name */
  };
  
  /*
   * Ext4 directory file types.  Only the low 3 bits are used.  The
   * other bits are reserved for now.
   */
  #define EXT4_FT_UNKNOWN		0
  #define EXT4_FT_REG_FILE	1
  #define EXT4_FT_DIR		2
  #define EXT4_FT_CHRDEV		3
  #define EXT4_FT_BLKDEV		4
  #define EXT4_FT_FIFO		5
  #define EXT4_FT_SOCK		6
  #define EXT4_FT_SYMLINK		7
  
  #define EXT4_FT_MAX		8
  
  /*
   * EXT4_DIR_PAD defines the directory entries boundaries
   *
   * NOTE: It must be a multiple of 4
   */
  #define EXT4_DIR_PAD			4
  #define EXT4_DIR_ROUND			(EXT4_DIR_PAD - 1)
  #define EXT4_DIR_REC_LEN(name_len)	(((name_len) + 8 + EXT4_DIR_ROUND) & \
  					 ~EXT4_DIR_ROUND)
  #define EXT4_MAX_REC_LEN		((1<<16)-1)
  
  /*
   * If we ever get support for fs block sizes > page_size, we'll need
   * to remove the #if statements in the next two functions...
   */
  static inline unsigned int
  ext4_rec_len_from_disk(__le16 dlen, unsigned blocksize)
  {
  	unsigned len = le16_to_cpu(dlen);
  
  #if (PAGE_CACHE_SIZE >= 65536)
  	if (len == EXT4_MAX_REC_LEN || len == 0)
  		return blocksize;
  	return (len & 65532) | ((len & 3) << 16);
  #else
  	return len;
  #endif
  }
  
  static inline __le16 ext4_rec_len_to_disk(unsigned len, unsigned blocksize)
  {
  	if ((len > blocksize) || (blocksize > (1 << 18)) || (len & 3))
  		BUG();
  #if (PAGE_CACHE_SIZE >= 65536)
  	if (len < 65536)
  		return cpu_to_le16(len);
  	if (len == blocksize) {
  		if (blocksize == 65536)
  			return cpu_to_le16(EXT4_MAX_REC_LEN);
  		else
  			return cpu_to_le16(0);
  	}
  	return cpu_to_le16((len & 65532) | ((len >> 16) & 3));
  #else
  	return cpu_to_le16(len);
  #endif
  }
  
  /*
   * Hash Tree Directory indexing
   * (c) Daniel Phillips, 2001
   */
  
  #define is_dx(dir) (EXT4_HAS_COMPAT_FEATURE(dir->i_sb, \
  				      EXT4_FEATURE_COMPAT_DIR_INDEX) && \
  		    ext4_test_inode_flag((dir), EXT4_INODE_INDEX))
  #define EXT4_DIR_LINK_MAX(dir) (!is_dx(dir) && (dir)->i_nlink >= EXT4_LINK_MAX)
  #define EXT4_DIR_LINK_EMPTY(dir) ((dir)->i_nlink == 2 || (dir)->i_nlink == 1)
  
  /* Legal values for the dx_root hash_version field: */
  
  #define DX_HASH_LEGACY		0
  #define DX_HASH_HALF_MD4	1
  #define DX_HASH_TEA		2
  #define DX_HASH_LEGACY_UNSIGNED	3
  #define DX_HASH_HALF_MD4_UNSIGNED	4
  #define DX_HASH_TEA_UNSIGNED		5
  
  #ifdef __KERNEL__
  
  /* hash info structure used by the directory hash */
  struct dx_hash_info
  {
  	u32		hash;
  	u32		minor_hash;
  	int		hash_version;
  	u32		*seed;
  };
  
  #define EXT4_HTREE_EOF	0x7fffffff
  
  /*
   * Control parameters used by ext4_htree_next_block
   */
  #define HASH_NB_ALWAYS		1
  
  
  /*
   * Describe an inode's exact location on disk and in memory
   */
  struct ext4_iloc
  {
  	struct buffer_head *bh;
  	unsigned long offset;
  	ext4_group_t block_group;
  };
  
  static inline struct ext4_inode *ext4_raw_inode(struct ext4_iloc *iloc)
  {
  	return (struct ext4_inode *) (iloc->bh->b_data + iloc->offset);
  }
  
  /*
   * This structure is stuffed into the struct file's private_data field
   * for directories.  It is where we put information so that we can do
   * readdir operations in hash tree order.
   */
  struct dir_private_info {
  	struct rb_root	root;
  	struct rb_node	*curr_node;
  	struct fname	*extra_fname;
  	loff_t		last_pos;
  	__u32		curr_hash;
  	__u32		curr_minor_hash;
  	__u32		next_hash;
  };
  
  /* calculate the first block number of the group */
  static inline ext4_fsblk_t
  ext4_group_first_block_no(struct super_block *sb, ext4_group_t group_no)
  {
  	return group_no * (ext4_fsblk_t)EXT4_BLOCKS_PER_GROUP(sb) +
  		le32_to_cpu(EXT4_SB(sb)->s_es->s_first_data_block);
  }
  
  /*
   * Special error return code only used by dx_probe() and its callers.
   */
  #define ERR_BAD_DX_DIR	-75000
  
  void ext4_get_group_no_and_offset(struct super_block *sb, ext4_fsblk_t blocknr,
  			ext4_group_t *blockgrpp, ext4_grpblk_t *offsetp);
  
  /*
   * Timeout and state flag for lazy initialization inode thread.
   */
  #define EXT4_DEF_LI_WAIT_MULT			10
  #define EXT4_DEF_LI_MAX_START_DELAY		5
  #define EXT4_LAZYINIT_QUIT			0x0001
  #define EXT4_LAZYINIT_RUNNING			0x0002
  
  /*
   * Lazy inode table initialization info
   */
  struct ext4_lazy_init {
  	unsigned long		li_state;
  	struct list_head	li_request_list;
  	struct mutex		li_list_mtx;
  };
  
  struct ext4_li_request {
  	struct super_block	*lr_super;
  	struct ext4_sb_info	*lr_sbi;
  	ext4_group_t		lr_next_group;
  	struct list_head	lr_request;
  	unsigned long		lr_next_sched;
  	unsigned long		lr_timeout;
  };
  
  struct ext4_features {
  	struct kobject f_kobj;
  	struct completion f_kobj_unregister;
  };
  
  /*
   * This structure will be used for multiple mount protection. It will be
   * written into the block number saved in the s_mmp_block field in the
   * superblock. Programs that check MMP should assume that if
   * SEQ_FSCK (or any unknown code above SEQ_MAX) is present then it is NOT safe
   * to use the filesystem, regardless of how old the timestamp is.
   */
  #define EXT4_MMP_MAGIC     0x004D4D50U /* ASCII for MMP */
  #define EXT4_MMP_SEQ_CLEAN 0xFF4D4D50U /* mmp_seq value for clean unmount */
  #define EXT4_MMP_SEQ_FSCK  0xE24D4D50U /* mmp_seq value when being fscked */
  #define EXT4_MMP_SEQ_MAX   0xE24D4D4FU /* maximum valid mmp_seq value */
  
  struct mmp_struct {
  	__le32	mmp_magic;		/* Magic number for MMP */
  	__le32	mmp_seq;		/* Sequence no. updated periodically */
  
  	/*
  	 * mmp_time, mmp_nodename & mmp_bdevname are only used for information
  	 * purposes and do not affect the correctness of the algorithm
  	 */
  	__le64	mmp_time;		/* Time last updated */
  	char	mmp_nodename[64];	/* Node which last updated MMP block */
  	char	mmp_bdevname[32];	/* Bdev which last updated MMP block */
  
  	/*
  	 * mmp_check_interval is used to verify if the MMP block has been
  	 * updated on the block device. The value is updated based on the
  	 * maximum time to write the MMP block during an update cycle.
  	 */
  	__le16	mmp_check_interval;
  
  	__le16	mmp_pad1;
  	__le32	mmp_pad2[227];
  };
  
  /* arguments passed to the mmp thread */
  struct mmpd_data {
  	struct buffer_head *bh; /* bh from initial read_mmp_block() */
  	struct super_block *sb;  /* super block of the fs */
  };
  
  /*
   * Check interval multiplier
   * The MMP block is written every update interval and initially checked every
   * update interval x the multiplier (the value is then adapted based on the
   * write latency). The reason is that writes can be delayed under load and we
   * don't want readers to incorrectly assume that the filesystem is no longer
   * in use.
   */
  #define EXT4_MMP_CHECK_MULT		2UL
  
  /*
   * Minimum interval for MMP checking in seconds.
   */
  #define EXT4_MMP_MIN_CHECK_INTERVAL	5UL
  
  /*
   * Maximum interval for MMP checking in seconds.
   */
  #define EXT4_MMP_MAX_CHECK_INTERVAL	300UL
  
  /*
   * Function prototypes
   */
  
  /*
   * Ok, these declarations are also in <linux/kernel.h> but none of the
   * ext4 source programs needs to include it so they are duplicated here.
   */
  # define NORET_TYPE	/**/
  # define ATTRIB_NORET	__attribute__((noreturn))
  # define NORET_AND	noreturn,
  
  /* bitmap.c */
  extern unsigned int ext4_count_free(struct buffer_head *, unsigned);
  
  /* balloc.c */
  extern unsigned int ext4_block_group(struct super_block *sb,
  			ext4_fsblk_t blocknr);
  extern ext4_grpblk_t ext4_block_group_offset(struct super_block *sb,
  			ext4_fsblk_t blocknr);
  extern int ext4_bg_has_super(struct super_block *sb, ext4_group_t group);
  extern unsigned long ext4_bg_num_gdb(struct super_block *sb,
  			ext4_group_t group);
  extern ext4_fsblk_t ext4_new_meta_blocks(handle_t *handle, struct inode *inode,
  					 ext4_fsblk_t goal,
  					 unsigned int flags,
  					 unsigned long *count,
  					 int *errp);
  extern int ext4_claim_free_blocks(struct ext4_sb_info *sbi,
  				  s64 nblocks, unsigned int flags);
  extern ext4_fsblk_t ext4_count_free_blocks(struct super_block *);
  extern void ext4_check_blocks_bitmap(struct super_block *);
  extern struct ext4_group_desc * ext4_get_group_desc(struct super_block * sb,
  						    ext4_group_t block_group,
  						    struct buffer_head ** bh);
  extern int ext4_should_retry_alloc(struct super_block *sb, int *retries);
  struct buffer_head *ext4_read_block_bitmap(struct super_block *sb,
  				      ext4_group_t block_group);
  extern unsigned ext4_init_block_bitmap(struct super_block *sb,
  				       struct buffer_head *bh,
  				       ext4_group_t group,
  				       struct ext4_group_desc *desc);
  #define ext4_free_blocks_after_init(sb, group, desc)			\
  		ext4_init_block_bitmap(sb, NULL, group, desc)
  
  /* dir.c */
  extern int __ext4_check_dir_entry(const char *, unsigned int, struct inode *,
  				  struct file *,
  				  struct ext4_dir_entry_2 *,
  				  struct buffer_head *, unsigned int);
  #define ext4_check_dir_entry(dir, filp, de, bh, offset)			\
  	unlikely(__ext4_check_dir_entry(__func__, __LINE__, (dir), (filp), \
  					(de), (bh), (offset)))
  extern int ext4_htree_store_dirent(struct file *dir_file, __u32 hash,
  				    __u32 minor_hash,
  				    struct ext4_dir_entry_2 *dirent);
  extern void ext4_htree_free_dir_info(struct dir_private_info *p);
  
  /* fsync.c */
  extern int ext4_sync_file(struct file *, int);
  extern int ext4_flush_completed_IO(struct inode *);
  
  /* hash.c */
  extern int ext4fs_dirhash(const char *name, int len, struct
  			  dx_hash_info *hinfo);
  
  /* ialloc.c */
  extern struct inode *ext4_new_inode(handle_t *, struct inode *, int,
  				    const struct qstr *qstr, __u32 goal);
  extern void ext4_free_inode(handle_t *, struct inode *);
  extern struct inode * ext4_orphan_get(struct super_block *, unsigned long);
  extern unsigned long ext4_count_free_inodes(struct super_block *);
  extern unsigned long ext4_count_dirs(struct super_block *);
  extern void ext4_check_inodes_bitmap(struct super_block *);
  extern void ext4_mark_bitmap_end(int start_bit, int end_bit, char *bitmap);
  extern int ext4_init_inode_table(struct super_block *sb,
  				 ext4_group_t group, int barrier);
  
  /* mballoc.c */
  extern long ext4_mb_stats;
  extern long ext4_mb_max_to_scan;
  extern int ext4_mb_init(struct super_block *, int);
  extern int ext4_mb_release(struct super_block *);
  extern ext4_fsblk_t ext4_mb_new_blocks(handle_t *,
  				struct ext4_allocation_request *, int *);
  extern int ext4_mb_reserve_blocks(struct super_block *, int);
  extern void ext4_discard_preallocations(struct inode *);
  extern int __init ext4_init_mballoc(void);
  extern void ext4_exit_mballoc(void);
  extern void ext4_free_blocks(handle_t *handle, struct inode *inode,
  			     struct buffer_head *bh, ext4_fsblk_t block,
  			     unsigned long count, int flags);
  extern int ext4_mb_add_groupinfo(struct super_block *sb,
  		ext4_group_t i, struct ext4_group_desc *desc);
  extern void ext4_add_groupblocks(handle_t *handle, struct super_block *sb,
  				ext4_fsblk_t block, unsigned long count);
  extern int ext4_trim_fs(struct super_block *, struct fstrim_range *);
  
  /* inode.c */
  struct buffer_head *ext4_getblk(handle_t *, struct inode *,
  						ext4_lblk_t, int, int *);
  struct buffer_head *ext4_bread(handle_t *, struct inode *,
  						ext4_lblk_t, int, int *);
  int ext4_get_block(struct inode *inode, sector_t iblock,
  				struct buffer_head *bh_result, int create);
  
  extern struct inode *ext4_iget(struct super_block *, unsigned long);
  extern int  ext4_write_inode(struct inode *, struct writeback_control *);
  extern int  ext4_setattr(struct dentry *, struct iattr *);
  extern int  ext4_getattr(struct vfsmount *mnt, struct dentry *dentry,
  				struct kstat *stat);
  extern void ext4_evict_inode(struct inode *);
  extern void ext4_clear_inode(struct inode *);
  extern int  ext4_sync_inode(handle_t *, struct inode *);
  extern void ext4_dirty_inode(struct inode *, int);
  extern int ext4_change_inode_journal_flag(struct inode *, int);
  extern int ext4_get_inode_loc(struct inode *, struct ext4_iloc *);
  extern int ext4_can_truncate(struct inode *inode);
  extern void ext4_truncate(struct inode *);
  extern int ext4_punch_hole(struct file *file, loff_t offset, loff_t length);
  extern int ext4_truncate_restart_trans(handle_t *, struct inode *, int nblocks);
  extern void ext4_set_inode_flags(struct inode *);
  extern void ext4_get_inode_flags(struct ext4_inode_info *);
  extern int ext4_alloc_da_blocks(struct inode *inode);
  extern void ext4_set_aops(struct inode *inode);
  extern int ext4_writepage_trans_blocks(struct inode *);
  extern int ext4_chunk_trans_blocks(struct inode *, int nrblocks);
  extern int ext4_block_truncate_page(handle_t *handle,
  		struct address_space *mapping, loff_t from);
  extern int ext4_block_zero_page_range(handle_t *handle,
  		struct address_space *mapping, loff_t from, loff_t length);
  extern int ext4_page_mkwrite(struct vm_area_struct *vma, struct vm_fault *vmf);
  extern qsize_t *ext4_get_reserved_space(struct inode *inode);
  extern void ext4_da_update_reserve_space(struct inode *inode,
  					int used, int quota_claim);
  /* ioctl.c */
  extern long ext4_ioctl(struct file *, unsigned int, unsigned long);
  extern long ext4_compat_ioctl(struct file *, unsigned int, unsigned long);
  
  /* migrate.c */
  extern int ext4_ext_migrate(struct inode *);
  
  /* namei.c */
  extern int ext4_orphan_add(handle_t *, struct inode *);
  extern int ext4_orphan_del(handle_t *, struct inode *);
  extern int ext4_htree_fill_tree(struct file *dir_file, __u32 start_hash,
  				__u32 start_minor_hash, __u32 *next_hash);
  
  /* resize.c */
  extern int ext4_group_add(struct super_block *sb,
  				struct ext4_new_group_data *input);
  extern int ext4_group_extend(struct super_block *sb,
  				struct ext4_super_block *es,
  				ext4_fsblk_t n_blocks_count);
  
  /* super.c */
  extern void __ext4_error(struct super_block *, const char *, unsigned int,
  			 const char *, ...)
  	__attribute__ ((format (printf, 4, 5)));
  #define ext4_error(sb, message...)	__ext4_error(sb, __func__,	\
  						     __LINE__, ## message)
  extern void ext4_error_inode(struct inode *, const char *, unsigned int,
  			     ext4_fsblk_t, const char *, ...)
  	__attribute__ ((format (printf, 5, 6)));
  extern void ext4_error_file(struct file *, const char *, unsigned int,
  			    ext4_fsblk_t, const char *, ...)
  	__attribute__ ((format (printf, 5, 6)));
  extern void __ext4_std_error(struct super_block *, const char *,
  			     unsigned int, int);
  extern void __ext4_abort(struct super_block *, const char *, unsigned int,
  		       const char *, ...)
  	__attribute__ ((format (printf, 4, 5)));
  #define ext4_abort(sb, message...)	__ext4_abort(sb, __func__, \
  						       __LINE__, ## message)
  extern void __ext4_warning(struct super_block *, const char *, unsigned int,
  			  const char *, ...)
  	__attribute__ ((format (printf, 4, 5)));
  #define ext4_warning(sb, message...)	__ext4_warning(sb, __func__, \
  						       __LINE__, ## message)
  extern void ext4_msg(struct super_block *, const char *, const char *, ...)
  	__attribute__ ((format (printf, 3, 4)));
  extern void __dump_mmp_msg(struct super_block *, struct mmp_struct *mmp,
  			   const char *, unsigned int, const char *);
  #define dump_mmp_msg(sb, mmp, msg)	__dump_mmp_msg(sb, mmp, __func__, \
  						       __LINE__, msg)
  extern void __ext4_grp_locked_error(const char *, unsigned int, \
  				    struct super_block *, ext4_group_t, \
  				    unsigned long, ext4_fsblk_t, \
  				    const char *, ...)
  	__attribute__ ((format (printf, 7, 8)));
  #define ext4_grp_locked_error(sb, grp, message...) \
  	__ext4_grp_locked_error(__func__, __LINE__, (sb), (grp), ## message)
  extern void ext4_update_dynamic_rev(struct super_block *sb);
  extern int ext4_update_compat_feature(handle_t *handle, struct super_block *sb,
  					__u32 compat);
  extern int ext4_update_rocompat_feature(handle_t *handle,
  					struct super_block *sb,	__u32 rocompat);
  extern int ext4_update_incompat_feature(handle_t *handle,
  					struct super_block *sb,	__u32 incompat);
  extern ext4_fsblk_t ext4_block_bitmap(struct super_block *sb,
  				      struct ext4_group_desc *bg);
  extern ext4_fsblk_t ext4_inode_bitmap(struct super_block *sb,
  				      struct ext4_group_desc *bg);
  extern ext4_fsblk_t ext4_inode_table(struct super_block *sb,
  				     struct ext4_group_desc *bg);
  extern __u32 ext4_free_blks_count(struct super_block *sb,
  				struct ext4_group_desc *bg);
  extern __u32 ext4_free_inodes_count(struct super_block *sb,
  				 struct ext4_group_desc *bg);
  extern __u32 ext4_used_dirs_count(struct super_block *sb,
  				struct ext4_group_desc *bg);
  extern __u32 ext4_itable_unused_count(struct super_block *sb,
  				   struct ext4_group_desc *bg);
  extern void ext4_block_bitmap_set(struct super_block *sb,
  				  struct ext4_group_desc *bg, ext4_fsblk_t blk);
  extern void ext4_inode_bitmap_set(struct super_block *sb,
  				  struct ext4_group_desc *bg, ext4_fsblk_t blk);
  extern void ext4_inode_table_set(struct super_block *sb,
  				 struct ext4_group_desc *bg, ext4_fsblk_t blk);
  extern void ext4_free_blks_set(struct super_block *sb,
  			       struct ext4_group_desc *bg, __u32 count);
  extern void ext4_free_inodes_set(struct super_block *sb,
  				struct ext4_group_desc *bg, __u32 count);
  extern void ext4_used_dirs_set(struct super_block *sb,
  				struct ext4_group_desc *bg, __u32 count);
  extern void ext4_itable_unused_set(struct super_block *sb,
  				   struct ext4_group_desc *bg, __u32 count);
  extern __le16 ext4_group_desc_csum(struct ext4_sb_info *sbi, __u32 group,
  				   struct ext4_group_desc *gdp);
  extern int ext4_group_desc_csum_verify(struct ext4_sb_info *sbi, __u32 group,
  				       struct ext4_group_desc *gdp);
  
  static inline ext4_fsblk_t ext4_blocks_count(struct ext4_super_block *es)
  {
  	return ((ext4_fsblk_t)le32_to_cpu(es->s_blocks_count_hi) << 32) |
  		le32_to_cpu(es->s_blocks_count_lo);
  }
  
  static inline ext4_fsblk_t ext4_r_blocks_count(struct ext4_super_block *es)
  {
  	return ((ext4_fsblk_t)le32_to_cpu(es->s_r_blocks_count_hi) << 32) |
  		le32_to_cpu(es->s_r_blocks_count_lo);
  }
  
  static inline ext4_fsblk_t ext4_free_blocks_count(struct ext4_super_block *es)
  {
  	return ((ext4_fsblk_t)le32_to_cpu(es->s_free_blocks_count_hi) << 32) |
  		le32_to_cpu(es->s_free_blocks_count_lo);
  }
  
  static inline void ext4_blocks_count_set(struct ext4_super_block *es,
  					 ext4_fsblk_t blk)
  {
  	es->s_blocks_count_lo = cpu_to_le32((u32)blk);
  	es->s_blocks_count_hi = cpu_to_le32(blk >> 32);
  }
  
  static inline void ext4_free_blocks_count_set(struct ext4_super_block *es,
  					      ext4_fsblk_t blk)
  {
  	es->s_free_blocks_count_lo = cpu_to_le32((u32)blk);
  	es->s_free_blocks_count_hi = cpu_to_le32(blk >> 32);
  }
  
  static inline void ext4_r_blocks_count_set(struct ext4_super_block *es,
  					   ext4_fsblk_t blk)
  {
  	es->s_r_blocks_count_lo = cpu_to_le32((u32)blk);
  	es->s_r_blocks_count_hi = cpu_to_le32(blk >> 32);
  }
  
  static inline loff_t ext4_isize(struct ext4_inode *raw_inode)
  {
  	if (S_ISREG(le16_to_cpu(raw_inode->i_mode)))
  		return ((loff_t)le32_to_cpu(raw_inode->i_size_high) << 32) |
  			le32_to_cpu(raw_inode->i_size_lo);
  	else
  		return (loff_t) le32_to_cpu(raw_inode->i_size_lo);
  }
  
  static inline void ext4_isize_set(struct ext4_inode *raw_inode, loff_t i_size)
  {
  	raw_inode->i_size_lo = cpu_to_le32(i_size);
  	raw_inode->i_size_high = cpu_to_le32(i_size >> 32);
  }
  
  static inline
  struct ext4_group_info *ext4_get_group_info(struct super_block *sb,
  					    ext4_group_t group)
  {
  	 struct ext4_group_info ***grp_info;
  	 long indexv, indexh;
  	 grp_info = EXT4_SB(sb)->s_group_info;
  	 indexv = group >> (EXT4_DESC_PER_BLOCK_BITS(sb));
  	 indexh = group & ((EXT4_DESC_PER_BLOCK(sb)) - 1);
  	 return grp_info[indexv][indexh];
  }
  
  /*
   * Reading s_groups_count requires using smp_rmb() afterwards.  See
   * the locking protocol documented in the comments of ext4_group_add()
   * in resize.c
   */
  static inline ext4_group_t ext4_get_groups_count(struct super_block *sb)
  {
  	ext4_group_t	ngroups = EXT4_SB(sb)->s_groups_count;
  
  	smp_rmb();
  	return ngroups;
  }
  
  static inline ext4_group_t ext4_flex_group(struct ext4_sb_info *sbi,
  					     ext4_group_t block_group)
  {
  	return block_group >> sbi->s_log_groups_per_flex;
  }
  
  static inline unsigned int ext4_flex_bg_size(struct ext4_sb_info *sbi)
  {
  	return 1 << sbi->s_log_groups_per_flex;
  }
  
  #define ext4_std_error(sb, errno)				\
  do {								\
  	if ((errno))						\
  		__ext4_std_error((sb), __func__, __LINE__, (errno));	\
  } while (0)
  
  #ifdef CONFIG_SMP
  /* Each CPU can accumulate percpu_counter_batch blocks in their local
   * counters. So we need to make sure we have free blocks more
   * than percpu_counter_batch  * nr_cpu_ids. Also add a window of 4 times.
   */
  #define EXT4_FREEBLOCKS_WATERMARK (4 * (percpu_counter_batch * nr_cpu_ids))
  #else
  #define EXT4_FREEBLOCKS_WATERMARK 0
  #endif
  
  static inline void ext4_update_i_disksize(struct inode *inode, loff_t newsize)
  {
  	/*
  	 * XXX: replace with spinlock if seen contended -bzzz
  	 */
  	down_write(&EXT4_I(inode)->i_data_sem);
  	if (newsize > EXT4_I(inode)->i_disksize)
  		EXT4_I(inode)->i_disksize = newsize;
  	up_write(&EXT4_I(inode)->i_data_sem);
  	return ;
  }
  
  struct ext4_group_info {
  	unsigned long   bb_state;
  	struct rb_root  bb_free_root;
  	ext4_grpblk_t	bb_first_free;	/* first free block */
  	ext4_grpblk_t	bb_free;	/* total free blocks */
  	ext4_grpblk_t	bb_fragments;	/* nr of freespace fragments */
  	ext4_grpblk_t	bb_largest_free_order;/* order of largest frag in BG */
  	struct          list_head bb_prealloc_list;
  #ifdef DOUBLE_CHECK
  	void            *bb_bitmap;
  #endif
  	struct rw_semaphore alloc_sem;
  	ext4_grpblk_t	bb_counters[];	/* Nr of free power-of-two-block
  					 * regions, index is order.
  					 * bb_counters[3] = 5 means
  					 * 5 free 8-block regions. */
  };
  
  #define EXT4_GROUP_INFO_NEED_INIT_BIT	0
  
  #define EXT4_MB_GRP_NEED_INIT(grp)	\
  	(test_bit(EXT4_GROUP_INFO_NEED_INIT_BIT, &((grp)->bb_state)))
  
  #define EXT4_MAX_CONTENTION		8
  #define EXT4_CONTENTION_THRESHOLD	2
  
  static inline spinlock_t *ext4_group_lock_ptr(struct super_block *sb,
  					      ext4_group_t group)
  {
  	return bgl_lock_ptr(EXT4_SB(sb)->s_blockgroup_lock, group);
  }
  
  /*
   * Returns true if the filesystem is busy enough that attempts to
   * access the block group locks has run into contention.
   */
  static inline int ext4_fs_is_busy(struct ext4_sb_info *sbi)
  {
  	return (atomic_read(&sbi->s_lock_busy) > EXT4_CONTENTION_THRESHOLD);
  }
  
  static inline void ext4_lock_group(struct super_block *sb, ext4_group_t group)
  {
  	spinlock_t *lock = ext4_group_lock_ptr(sb, group);
  	if (spin_trylock(lock))
  		/*
  		 * We're able to grab the lock right away, so drop the
  		 * lock contention counter.
  		 */
  		atomic_add_unless(&EXT4_SB(sb)->s_lock_busy, -1, 0);
  	else {
  		/*
  		 * The lock is busy, so bump the contention counter,
  		 * and then wait on the spin lock.
  		 */
  		atomic_add_unless(&EXT4_SB(sb)->s_lock_busy, 1,
  				  EXT4_MAX_CONTENTION);
  		spin_lock(lock);
  	}
  }
  
  static inline void ext4_unlock_group(struct super_block *sb,
  					ext4_group_t group)
  {
  	spin_unlock(ext4_group_lock_ptr(sb, group));
  }
  
  static inline void ext4_mark_super_dirty(struct super_block *sb)
  {
  	if (EXT4_SB(sb)->s_journal == NULL)
  		sb->s_dirt =1;
  }
  
  /*
   * Inodes and files operations
   */
  
  /* dir.c */
  extern const struct file_operations ext4_dir_operations;
  
  /* file.c */
  extern const struct inode_operations ext4_file_inode_operations;
  extern const struct file_operations ext4_file_operations;
  extern loff_t ext4_llseek(struct file *file, loff_t offset, int origin);
  
  /* namei.c */
  extern const struct inode_operations ext4_dir_inode_operations;
  extern const struct inode_operations ext4_special_inode_operations;
  extern struct dentry *ext4_get_parent(struct dentry *child);
  
  /* symlink.c */
  extern const struct inode_operations ext4_symlink_inode_operations;
  extern const struct inode_operations ext4_fast_symlink_inode_operations;
  
  /* block_validity */
  extern void ext4_release_system_zone(struct super_block *sb);
  extern int ext4_setup_system_zone(struct super_block *sb);
  extern int __init ext4_init_system_zone(void);
  extern void ext4_exit_system_zone(void);
  extern int ext4_data_block_valid(struct ext4_sb_info *sbi,
  				 ext4_fsblk_t start_blk,
  				 unsigned int count);
  
  /* extents.c */
  extern int ext4_ext_tree_init(handle_t *handle, struct inode *);
  extern int ext4_ext_writepage_trans_blocks(struct inode *, int);
  extern int ext4_ext_index_trans_blocks(struct inode *inode, int nrblocks,
  				       int chunk);
  extern int ext4_ext_map_blocks(handle_t *handle, struct inode *inode,
  			       struct ext4_map_blocks *map, int flags);
  extern void ext4_ext_truncate(struct inode *);
  extern int ext4_ext_punch_hole(struct file *file, loff_t offset,
  				loff_t length);
  extern void ext4_ext_init(struct super_block *);
  extern void ext4_ext_release(struct super_block *);
  extern long ext4_fallocate(struct file *file, int mode, loff_t offset,
  			  loff_t len);
  extern int ext4_convert_unwritten_extents(struct inode *inode, loff_t offset,
  			  ssize_t len);
  extern int ext4_map_blocks(handle_t *handle, struct inode *inode,
  			   struct ext4_map_blocks *map, int flags);
  extern int ext4_fiemap(struct inode *inode, struct fiemap_extent_info *fieinfo,
  			__u64 start, __u64 len);
  /* move_extent.c */
  extern int ext4_move_extents(struct file *o_filp, struct file *d_filp,
  			     __u64 start_orig, __u64 start_donor,
  			     __u64 len, __u64 *moved_len);
  
  /* page-io.c */
  extern int __init ext4_init_pageio(void);
  extern void ext4_exit_pageio(void);
  extern void ext4_ioend_wait(struct inode *);
  extern void ext4_free_io_end(ext4_io_end_t *io);
  extern ext4_io_end_t *ext4_init_io_end(struct inode *inode, gfp_t flags);
  extern int ext4_end_io_nolock(ext4_io_end_t *io);
  extern void ext4_io_submit(struct ext4_io_submit *io);
  extern int ext4_bio_write_page(struct ext4_io_submit *io,
  			       struct page *page,
  			       int len,
  			       struct writeback_control *wbc);
  
  /* mmp.c */
  extern int ext4_multi_mount_protect(struct super_block *, ext4_fsblk_t);
  
  /* BH_Uninit flag: blocks are allocated but uninitialized on disk */
  enum ext4_state_bits {
  	BH_Uninit	/* blocks are allocated but uninitialized on disk */
  	  = BH_JBDPrivateStart,
  };
  
  BUFFER_FNS(Uninit, uninit)
  TAS_BUFFER_FNS(Uninit, uninit)
  
  /*
   * Add new method to test wether block and inode bitmaps are properly
   * initialized. With uninit_bg reading the block from disk is not enough
   * to mark the bitmap uptodate. We need to also zero-out the bitmap
   */
  #define BH_BITMAP_UPTODATE BH_JBDPrivateStart
  
  static inline int bitmap_uptodate(struct buffer_head *bh)
  {
  	return (buffer_uptodate(bh) &&
  			test_bit(BH_BITMAP_UPTODATE, &(bh)->b_state));
  }
  static inline void set_bitmap_uptodate(struct buffer_head *bh)
  {
  	set_bit(BH_BITMAP_UPTODATE, &(bh)->b_state);
  }
  
  #define in_range(b, first, len)	((b) >= (first) && (b) <= (first) + (len) - 1)
  
  /* For ioend & aio unwritten conversion wait queues */
  #define EXT4_WQ_HASH_SZ		37
  #define ext4_ioend_wq(v)   (&ext4__ioend_wq[((unsigned long)(v)) %\
  					    EXT4_WQ_HASH_SZ])
  #define ext4_aio_mutex(v)  (&ext4__aio_mutex[((unsigned long)(v)) %\
  					     EXT4_WQ_HASH_SZ])
  extern wait_queue_head_t ext4__ioend_wq[EXT4_WQ_HASH_SZ];
  extern struct mutex ext4__aio_mutex[EXT4_WQ_HASH_SZ];
  
  #endif	/* __KERNEL__ */
  
  #endif	/* _EXT4_H */
  