sysv_fs.h

LINUX1.0内核源代码,学习LINUX编程的一定要看。

#ifndef _LINUX_SYSV_FS_H
#define _LINUX_SYSV_FS_H

/*
 * The SystemV/Coherent filesystem constants/structures/macros
 */


/* This code assumes
   - a little endian processor like 386,
   - sizeof(short) = 2, sizeof(int) = 4, sizeof(long) = 4,
   - alignof(short) = 2, alignof(long) = 4.
*/

#ifdef __GNUC__
#define __packed2__  __attribute__ ((packed, aligned(2)))
#else
#error I want gcc!
#endif

#include <linux/stat.h>		/* declares S_IFLNK etc. */
#include <linux/sched.h>	/* declares wake_up() */
#include <linux/sysv_fs_sb.h>	/* defines the sv_... shortcuts */


/* Layout on disk */
/* ============== */


/* The block size is sb->sv_block_size which may be smaller than BLOCK_SIZE. */

/* zones (= data allocation units) are blocks */

/* On Coherent FS, 32 bit quantities are stored using (I quote the Coherent
   manual) a "canonical byte ordering". This is the PDP-11 byte ordering:
   x = 2^24 * byte3 + 2^16 * byte2 + 2^8 * byte1 + byte0 is stored
   as { byte2, byte3, byte0, byte1 }. We need conversions.
*/

typedef unsigned long coh_ulong;

static inline coh_ulong to_coh_ulong (unsigned long x)
{
	return ((x & 0xffff) << 16) | ((x & 0xffff0000) >> 16);
}

static inline unsigned long from_coh_ulong (coh_ulong x)
{
	return ((x & 0xffff) << 16) | ((x & 0xffff0000) >> 16);
}

/* inode numbers are 16 bit */

typedef unsigned short sysv_ino_t;

/* Block numbers are 24 bit, sometimes stored in 32 bit.
   On Coherent FS, they are always stored in PDP-11 manner: the least
   significant 16 bits come last.
*/

typedef unsigned long sysv_zone_t;

/* Among the blocks ... */
/* Xenix FS, Coherent FS: block 0 is the boot block, block 1 the super-block.
   SystemV FS: block 0 contains both the boot sector and the super-block. */
/* The first inode zone is sb->sv_firstinodezone (1 or 2). */

/* Among the inodes ... */
/* 0 is non-existent */
#define SYSV_BADBL_INO	1	/* inode of bad blocks file */
#define SYSV_ROOT_INO	2	/* inode of root directory */


/* Xenix super-block data on disk */
#define XENIX_NICINOD	100	/* number of inode cache entries */
#define XENIX_NICFREE	100	/* number of free block list chunk entries */
struct xenix_super_block {
	unsigned short s_isize; /* index of first data zone */
	unsigned long  s_fsize __packed2__; /* total number of zones of this fs */
	/* the start of the free block list: */
	unsigned short s_nfree;	/* number of free blocks in s_free, <= XENIX_NICFREE */
	unsigned long  s_free[XENIX_NICFREE]; /* first free block list chunk */
	/* the cache of free inodes: */
	unsigned short s_ninode; /* number of free inodes in s_inode, <= XENIX_NICINOD */
	sysv_ino_t     s_inode[XENIX_NICINOD]; /* some free inodes */
	/* locks, not used by Linux: */
	char	       s_flock;	/* lock during free block list manipulation */
	char	       s_ilock;	/* lock during inode cache manipulation */
	char	       s_fmod;	/* super-block modified flag */
	char	       s_ronly;	/* flag whether fs is mounted read-only */
	unsigned long  s_time __packed2__; /* time of last super block update */
	unsigned long  s_tfree __packed2__; /* total number of free zones */
	unsigned short s_tinode;	/* total number of free inodes */
	short	       s_dinfo[4];	/* device information ?? */
	char	       s_fname[6];	/* file system volume name */
	char	       s_fpack[6];	/* file system pack name */
	char	       s_clean;		/* set to 0x46 when filesystem is properly unmounted */
	char	       s_fill[371];
	long	       s_magic;		/* version of file system */
	long	       s_type;		/* type of file system: 1 for 512 byte blocks
								2 for 1024 byte blocks */
};

/* Xenix free list block on disk */
struct xenix_freelist_chunk {
	unsigned short fl_nfree;	/* number of free blocks in fl_free, <= XENIX_NICFREE] */
	unsigned long  fl_free[XENIX_NICFREE] __packed2__;
};

/* SystemV FS comes in two variants:
 * sysv2: System V Release 2 (e.g. Microport), structure elements aligned(2).
 * sysv4: System V Release 4 (e.g. Consensys), structure elements aligned(4).
 */
#define SYSV_NICINOD	100	/* number of inode cache entries */
#define SYSV_NICFREE	50	/* number of free block list chunk entries */

/* SystemV4 super-block data on disk */
struct sysv4_super_block {
	unsigned short s_isize; /* index of first data zone */
	unsigned long  s_fsize;	/* total number of zones of this fs */
	/* the start of the free block list: */
	unsigned short s_nfree;	/* number of free blocks in s_free, <= SYSV_NICFREE */
	unsigned long  s_free[SYSV_NICFREE]; /* first free block list chunk */
	/* the cache of free inodes: */
	unsigned short s_ninode; /* number of free inodes in s_inode, <= SYSV_NICINOD */
	sysv_ino_t     s_inode[SYSV_NICINOD]; /* some free inodes */
	/* locks, not used by Linux: */
	char	       s_flock;	/* lock during free block list manipulation */
	char	       s_ilock;	/* lock during inode cache manipulation */
	char	       s_fmod;	/* super-block modified flag */
	char	       s_ronly;	/* flag whether fs is mounted read-only */
	unsigned long  s_time;	/* time of last super block update */
	short	       s_dinfo[4];	/* device information ?? */
	unsigned long  s_tfree;	/* total number of free zones */
	unsigned short s_tinode;	/* total number of free inodes */
	char	       s_fname[6];	/* file system volume name */
	char	       s_fpack[6];	/* file system pack name */
	long	       s_fill[12];
	long	       s_state;		/* file system state */
	long	       s_magic;		/* version of file system */
	long	       s_type;		/* type of file system: 1 for 512 byte blocks
								2 for 1024 byte blocks */
};

/* SystemV4 free list block on disk */
struct sysv4_freelist_chunk {
	unsigned short fl_nfree;	/* number of free blocks in fl_free, <= SYSV_NICFREE] */
	unsigned long  fl_free[SYSV_NICFREE];
};

/* SystemV2 super-block data on disk */
struct sysv2_super_block {
	unsigned short s_isize; /* index of first data zone */
	unsigned long  s_fsize __packed2__; /* total number of zones of this fs */
	/* the start of the free block list: */
	unsigned short s_nfree;	/* number of free blocks in s_free, <= SYSV_NICFREE */
	unsigned long  s_free[SYSV_NICFREE]; /* first free block list chunk */
	/* the cache of free inodes: */
	unsigned short s_ninode; /* number of free inodes in s_inode, <= SYSV_NICINOD */
	sysv_ino_t     s_inode[SYSV_NICINOD]; /* some free inodes */
	/* locks, not used by Linux: */
	char	       s_flock;	/* lock during free block list manipulation */
	char	       s_ilock;	/* lock during inode cache manipulation */
	char	       s_fmod;	/* super-block modified flag */
	char	       s_ronly;	/* flag whether fs is mounted read-only */
	unsigned long  s_time __packed2__; /* time of last super block update */
	short	       s_dinfo[4];	/* device information ?? */
	unsigned long  s_tfree __packed2__; /* total number of free zones */
	unsigned short s_tinode;	/* total number of free inodes */
	char	       s_fname[6];	/* file system volume name */
	char	       s_fpack[6];	/* file system pack name */
	long	       s_fill[14];
	long	       s_state;		/* file system state */
	long	       s_magic;		/* version of file system */
	long	       s_type;		/* type of file system: 1 for 512 byte blocks
								2 for 1024 byte blocks */
};

/* SystemV2 free list block on disk */
struct sysv2_freelist_chunk {
	unsigned short fl_nfree;	/* number of free blocks in fl_free, <= SYSV_NICFREE] */
	unsigned long  fl_free[SYSV_NICFREE] __packed2__;
};

/* Coherent super-block data on disk */
#define COH_NICINOD	100	/* number of inode cache entries */
#define COH_NICFREE	64	/* number of free block list chunk entries */
struct coh_super_block {
	unsigned short s_isize; /* index of first data zone */
	coh_ulong      s_fsize __packed2__; /* total number of zones of this fs */
	/* the start of the free block list: */
	unsigned short s_nfree;	/* number of free blocks in s_free, <= COH_NICFREE */
	coh_ulong      s_free[COH_NICFREE] __packed2__; /* first free block list chunk */
	/* the cache of free inodes: */
	unsigned short s_ninode; /* number of free inodes in s_inode, <= COH_NICINOD */
	sysv_ino_t     s_inode[COH_NICINOD]; /* some free inodes */
	/* locks, not used by Linux: */
	char	       s_flock;	/* lock during free block list manipulation */
	char	       s_ilock;	/* lock during inode cache manipulation */
	char	       s_fmod;	/* super-block modified flag */
	char	       s_ronly;	/* flag whether fs is mounted read-only */
	coh_ulong      s_time __packed2__; /* time of last super block update */
	coh_ulong      s_tfree __packed2__; /* total number of free zones */
	unsigned short s_tinode;	/* total number of free inodes */
	unsigned short s_interleave_m;	/* interleave factor */
	unsigned short s_interleave_n;
	char	       s_fname[6];	/* file system volume name */
	char	       s_fpack[6];	/* file system pack name */
	unsigned long  s_unique;	/* zero, not used */
};

/* Coherent free list block on disk */
struct coh_freelist_chunk {
	unsigned short fl_nfree;	/* number of free blocks in fl_free, <= COH_NICFREE] */
	unsigned long  fl_free[COH_NICFREE] __packed2__;
};


/* SystemV/Coherent inode data on disk */