fs.h

最早的linux操作系统源代码（3）

/*
 * This file has definitions for some important file table
 * structures etc.
 */

#ifndef _FS_H
#define _FS_H

#include <sys/types.h>

/* devices are as follows: (same as minix, so we can use the minix
 * file system. These are major numbers.)
 *
 * 0 - unused (nodev)
 * 1 - /dev/mem
 * 2 - /dev/fd
 * 3 - /dev/hd
 * 4 - /dev/ttyx
 * 5 - /dev/tty
 * 6 - /dev/lp
 * 7 - unnamed pipes
 */

#define IS_BLOCKDEV(x) ((x)==2 || (x)==3)

#define READ 0
#define WRITE 1

void buffer_init(void);

#define MAJOR(a) (((unsigned)(a))>>8)
#define MINOR(a) ((a)&0xff)

#define NAME_LEN 14

#define I_MAP_SLOTS 8
#define Z_MAP_SLOTS 8
#define SUPER_MAGIC 0x137F

#define NR_OPEN 20
#define NR_INODE 32
#define NR_FILE 64
#define NR_SUPER 8
#define NR_HASH 307
#define NR_BUFFERS nr_buffers
#define BLOCK_SIZE 1024
#ifndef NULL
#define NULL ((void *) 0)
#endif

#define INODES_PER_BLOCK ((BLOCK_SIZE)/(sizeof (struct d_inode)))
#define DIR_ENTRIES_PER_BLOCK ((BLOCK_SIZE)/(sizeof (struct dir_entry)))

typedef char buffer_block[BLOCK_SIZE];

struct buffer_head {
	char * b_data;			/* pointer to data block (1024 bytes) */
	unsigned short b_dev;		/* device (0 = free) */
	unsigned short b_blocknr;	/* block number */
	unsigned char b_uptodate;
	unsigned char b_dirt;		/* 0-clean,1-dirty */
	unsigned char b_count;		/* users using this block */
	unsigned char b_lock;		/* 0 - ok, 1 -locked */
	struct task_struct * b_wait;
	struct buffer_head * b_prev;
	struct buffer_head * b_next;
	struct buffer_head * b_prev_free;
	struct buffer_head * b_next_free;
};

struct d_inode {
	unsigned short i_mode;
	unsigned short i_uid;
	unsigned long i_size;
	unsigned long i_time;
	unsigned char i_gid;
	unsigned char i_nlinks;
	unsigned short i_zone[9];
};

struct m_inode {
	unsigned short i_mode;
	unsigned short i_uid;
	unsigned long i_size;
	unsigned long i_mtime;
	unsigned char i_gid;
	unsigned char i_nlinks;
	unsigned short i_zone[9];
/* these are in memory also */
	struct task_struct * i_wait;
	unsigned long i_atime;
	unsigned long i_ctime;
	unsigned short i_dev;
	unsigned short i_num;
	unsigned short i_count;
	unsigned char i_lock;
	unsigned char i_dirt;
	unsigned char i_pipe;
	unsigned char i_mount;
	unsigned char i_seek;
	unsigned char i_update;
};

#define PIPE_HEAD(inode) (((long *)((inode).i_zone))[0])
#define PIPE_TAIL(inode) (((long *)((inode).i_zone))[1])
#define PIPE_SIZE(inode) ((PIPE_HEAD(inode)-PIPE_TAIL(inode))&(PAGE_SIZE-1))
#define PIPE_EMPTY(inode) (PIPE_HEAD(inode)==PIPE_TAIL(inode))
#define PIPE_FULL(inode) (PIPE_SIZE(inode)==(PAGE_SIZE-1))
#define INC_PIPE(head) \
__asm__("incl %0\n\tandl $4095,%0"::"m" (head))

struct file {
	unsigned short f_mode;
	unsigned short f_flags;
	unsigned short f_count;
	struct m_inode * f_inode;
	off_t f_pos;
};

struct super_block {
	unsigned short s_ninodes;
	unsigned short s_nzones;
	unsigned short s_imap_blocks;
	unsigned short s_zmap_blocks;
	unsigned short s_firstdatazone;
	unsigned short s_log_zone_size;
	unsigned long s_max_size;
	unsigned short s_magic;
/* These are only in memory */
	struct buffer_head * s_imap[8];
	struct buffer_head * s_zmap[8];
	unsigned short s_dev;
	struct m_inode * s_isup;
	struct m_inode * s_imount;
	unsigned long s_time;
	unsigned char s_rd_only;
	unsigned char s_dirt;
};

struct dir_entry {
	unsigned short inode;
	char name[NAME_LEN];
};

extern struct m_inode inode_table[NR_INODE];
extern struct file file_table[NR_FILE];
extern struct super_block super_block[NR_SUPER];
extern struct buffer_head * start_buffer;
extern int nr_buffers;

extern void truncate(struct m_inode * inode);
extern void sync_inodes(void);
extern void wait_on(struct m_inode * inode);
extern int bmap(struct m_inode * inode,int block);
extern int create_block(struct m_inode * inode,int block);
extern struct m_inode * namei(const char * pathname);
extern int open_namei(const char * pathname, int flag, int mode,
	struct m_inode ** res_inode);
extern void iput(struct m_inode * inode);
extern struct m_inode * iget(int dev,int nr);
extern struct m_inode * get_empty_inode(void);
extern struct m_inode * get_pipe_inode(void);
extern struct buffer_head * get_hash_table(int dev, int block);
extern struct buffer_head * getblk(int dev, int block);
extern void ll_rw_block(int rw, struct buffer_head * bh);
extern void brelse(struct buffer_head * buf);
extern struct buffer_head * bread(int dev,int block);
extern int new_block(int dev);
extern void free_block(int dev, int block);
extern struct m_inode * new_inode(int dev);
extern void free_inode(struct m_inode * inode);

extern void mount_root(void);

extern inline struct super_block * get_super(int dev)
{
	struct super_block * s;

	for(s = 0+super_block;s < NR_SUPER+super_block; s++)
		if (s->s_dev == dev)
			return s;
	return NULL;
}

#endif