text: #ifndef _SYSV_H
  #define _SYSV_H
  
  #include <linux/buffer_head.h>
  
  typedef __u16 __bitwise __fs16;
  typedef __u32 __bitwise __fs32;
  
  #include <linux/sysv_fs.h>
  
  /*
   * SystemV/V7/Coherent super-block data in memory
   *
   * The SystemV/V7/Coherent superblock contains dynamic data (it gets modified
   * while the system is running). This is in contrast to the Minix and Berkeley
   * filesystems (where the superblock is never modified). This affects the
   * sync() operation: we must keep the superblock in a disk buffer and use this
   * one as our "working copy".
   */
  
  struct sysv_sb_info {
  	struct super_block *s_sb;	/* VFS superblock */
  	int	       s_type;		/* file system type: FSTYPE_{XENIX|SYSV|COH} */
  	char	       s_bytesex;	/* bytesex (le/be/pdp) */
  	char	       s_truncate;	/* if 1: names > SYSV_NAMELEN chars are truncated */
  					/* if 0: they are disallowed (ENAMETOOLONG) */
  	nlink_t        s_link_max;	/* max number of hard links to a file */
  	unsigned int   s_inodes_per_block;	/* number of inodes per block */
  	unsigned int   s_inodes_per_block_1;	/* inodes_per_block - 1 */
  	unsigned int   s_inodes_per_block_bits;	/* log2(inodes_per_block) */
  	unsigned int   s_ind_per_block;		/* number of indirections per block */
  	unsigned int   s_ind_per_block_bits;	/* log2(ind_per_block) */
  	unsigned int   s_ind_per_block_2;	/* ind_per_block ^ 2 */
  	unsigned int   s_toobig_block;		/* 10 + ipb + ipb^2 + ipb^3 */
  	unsigned int   s_block_base;	/* physical block number of block 0 */
  	unsigned short s_fic_size;	/* free inode cache size, NICINOD */
  	unsigned short s_flc_size;	/* free block list chunk size, NICFREE */
  	/* The superblock is kept in one or two disk buffers: */
  	struct buffer_head *s_bh1;
  	struct buffer_head *s_bh2;
  	/* These are pointers into the disk buffer, to compensate for
  	   different superblock layout. */
  	char *         s_sbd1;		/* entire superblock data, for part 1 */
  	char *         s_sbd2;		/* entire superblock data, for part 2 */
  	__fs16         *s_sb_fic_count;	/* pointer to s_sbd->s_ninode */
          sysv_ino_t     *s_sb_fic_inodes; /* pointer to s_sbd->s_inode */
  	__fs16         *s_sb_total_free_inodes; /* pointer to s_sbd->s_tinode */
  	__fs16         *s_bcache_count;	/* pointer to s_sbd->s_nfree */
  	sysv_zone_t    *s_bcache;	/* pointer to s_sbd->s_free */
  	__fs32         *s_free_blocks;	/* pointer to s_sbd->s_tfree */
  	__fs32         *s_sb_time;	/* pointer to s_sbd->s_time */
  	__fs32         *s_sb_state;	/* pointer to s_sbd->s_state, only FSTYPE_SYSV */
  	/* We keep those superblock entities that don't change here;
  	   this saves us an indirection and perhaps a conversion. */
  	u32            s_firstinodezone; /* index of first inode zone */
  	u32            s_firstdatazone;	/* same as s_sbd->s_isize */
  	u32            s_ninodes;	/* total number of inodes */
  	u32            s_ndatazones;	/* total number of data zones */
  	u32            s_nzones;	/* same as s_sbd->s_fsize */
  	u16	       s_namelen;       /* max length of dir entry */
  	int	       s_forced_ro;
  };
  
  /*
   * SystemV/V7/Coherent FS inode data in memory
   */
  struct sysv_inode_info {
  	__fs32		i_data[13];
  	u32		i_dir_start_lookup;
  	struct inode	vfs_inode;
  };
  
  
  static inline struct sysv_inode_info *SYSV_I(struct inode *inode)
  {
  	return list_entry(inode, struct sysv_inode_info, vfs_inode);
  }
  
  static inline struct sysv_sb_info *SYSV_SB(struct super_block *sb)
  {
  	return sb->s_fs_info;
  }
  
  
  /* identify the FS in memory */
  enum {
  	FSTYPE_NONE = 0,
  	FSTYPE_XENIX,
  	FSTYPE_SYSV4,
  	FSTYPE_SYSV2,
  	FSTYPE_COH,
  	FSTYPE_V7,
  	FSTYPE_AFS,
  	FSTYPE_END,
  };
  
  #define SYSV_MAGIC_BASE		0x012FF7B3
  
  #define XENIX_SUPER_MAGIC	(SYSV_MAGIC_BASE+FSTYPE_XENIX)
  #define SYSV4_SUPER_MAGIC	(SYSV_MAGIC_BASE+FSTYPE_SYSV4)
  #define SYSV2_SUPER_MAGIC	(SYSV_MAGIC_BASE+FSTYPE_SYSV2)
  #define COH_SUPER_MAGIC		(SYSV_MAGIC_BASE+FSTYPE_COH)
  
  
  /* Admissible values for i_nlink: 0.._LINK_MAX */
  enum {
  	XENIX_LINK_MAX	=	126,	/* ?? */
  	SYSV_LINK_MAX	=	126,	/* 127? 251? */
  	V7_LINK_MAX     =	126,	/* ?? */
  	COH_LINK_MAX	=	10000,
  };
  
  
  static inline void dirty_sb(struct super_block *sb)
  {
  	struct sysv_sb_info *sbi = SYSV_SB(sb);
  
  	mark_buffer_dirty(sbi->s_bh1);
  	if (sbi->s_bh1 != sbi->s_bh2)
  		mark_buffer_dirty(sbi->s_bh2);
  	sb->s_dirt = 1;
  }
  
  
  /* ialloc.c */
  extern struct sysv_inode *sysv_raw_inode(struct super_block *, unsigned,
  			struct buffer_head **);
  extern struct inode * sysv_new_inode(const struct inode *, mode_t);
  extern void sysv_free_inode(struct inode *);
  extern unsigned long sysv_count_free_inodes(struct super_block *);
  
  /* balloc.c */
  extern sysv_zone_t sysv_new_block(struct super_block *);
  extern void sysv_free_block(struct super_block *, sysv_zone_t);
  extern unsigned long sysv_count_free_blocks(struct super_block *);
  
  /* itree.c */
  extern void sysv_truncate(struct inode *);
  
  /* inode.c */
  extern int sysv_write_inode(struct inode *, int);
  extern int sysv_sync_inode(struct inode *);
  extern int sysv_sync_file(struct file *, struct dentry *, int);
  extern void sysv_set_inode(struct inode *, dev_t);
  extern int sysv_getattr(struct vfsmount *, struct dentry *, struct kstat *);
  
  /* dir.c */
  extern struct sysv_dir_entry *sysv_find_entry(struct dentry *, struct page **);
  extern int sysv_add_link(struct dentry *, struct inode *);
  extern int sysv_delete_entry(struct sysv_dir_entry *, struct page *);
  extern int sysv_make_empty(struct inode *, struct inode *);
  extern int sysv_empty_dir(struct inode *);
  extern void sysv_set_link(struct sysv_dir_entry *, struct page *,
  			struct inode *);
  extern struct sysv_dir_entry *sysv_dotdot(struct inode *, struct page **);
  extern ino_t sysv_inode_by_name(struct dentry *);
  
  
  extern struct inode_operations sysv_file_inode_operations;
  extern struct inode_operations sysv_dir_inode_operations;
  extern struct inode_operations sysv_fast_symlink_inode_operations;
  extern struct file_operations sysv_file_operations;
  extern struct file_operations sysv_dir_operations;
  extern struct address_space_operations sysv_aops;
  extern struct super_operations sysv_sops;
  extern struct dentry_operations sysv_dentry_operations;
  
  
  enum {
  	BYTESEX_LE,
  	BYTESEX_PDP,
  	BYTESEX_BE,
  };
  
  static inline u32 PDP_swab(u32 x)
  {
  #ifdef __LITTLE_ENDIAN
  	return ((x & 0xffff) << 16) | ((x & 0xffff0000) >> 16);
  #else
  #ifdef __BIG_ENDIAN
  	return ((x & 0xff00ff) << 8) | ((x & 0xff00ff00) >> 8);
  #else
  #error BYTESEX
  #endif
  #endif
  }
  
  static inline __u32 fs32_to_cpu(struct sysv_sb_info *sbi, __fs32 n)
  {
  	if (sbi->s_bytesex == BYTESEX_PDP)
  		return PDP_swab((__force __u32)n);
  	else if (sbi->s_bytesex == BYTESEX_LE)
  		return le32_to_cpu((__force __le32)n);
  	else
  		return be32_to_cpu((__force __be32)n);
  }
  
  static inline __fs32 cpu_to_fs32(struct sysv_sb_info *sbi, __u32 n)
  {
  	if (sbi->s_bytesex == BYTESEX_PDP)
  		return (__force __fs32)PDP_swab(n);
  	else if (sbi->s_bytesex == BYTESEX_LE)
  		return (__force __fs32)cpu_to_le32(n);
  	else
  		return (__force __fs32)cpu_to_be32(n);
  }
  
  static inline __fs32 fs32_add(struct sysv_sb_info *sbi, __fs32 *n, int d)
  {
  	if (sbi->s_bytesex == BYTESEX_PDP)
  		*(__u32*)n = PDP_swab(PDP_swab(*(__u32*)n)+d);
  	else if (sbi->s_bytesex == BYTESEX_LE)
  		*(__le32*)n = cpu_to_le32(le32_to_cpu(*(__le32*)n)+d);
  	else
  		*(__be32*)n = cpu_to_be32(be32_to_cpu(*(__be32*)n)+d);
  	return *n;
  }
  
  static inline __u16 fs16_to_cpu(struct sysv_sb_info *sbi, __fs16 n)
  {
  	if (sbi->s_bytesex != BYTESEX_BE)
  		return le16_to_cpu((__force __le16)n);
  	else
  		return be16_to_cpu((__force __be16)n);
  }
  
  static inline __fs16 cpu_to_fs16(struct sysv_sb_info *sbi, __u16 n)
  {
  	if (sbi->s_bytesex != BYTESEX_BE)
  		return (__force __fs16)cpu_to_le16(n);
  	else
  		return (__force __fs16)cpu_to_be16(n);
  }
  
  static inline __fs16 fs16_add(struct sysv_sb_info *sbi, __fs16 *n, int d)
  {
  	if (sbi->s_bytesex != BYTESEX_BE)
  		*(__le16*)n = cpu_to_le16(le16_to_cpu(*(__le16 *)n)+d);
  	else
  		*(__be16*)n = cpu_to_be16(be16_to_cpu(*(__be16 *)n)+d);
  	return *n;
  }
  
  #endif /* _SYSV_H */
  