sysv_fs.h

LINUX1.0内核源代码,学习LINUX编程的一定要看。

struct sysv_inode {
	unsigned short i_mode;
	unsigned short i_nlink;
	unsigned short i_uid;
	unsigned short i_gid;
	unsigned long  i_size;
	union { /* directories, regular files, ... */
		char i_addb[3*(10+1+1+1)+1]; /* zone numbers: max. 10 data blocks,
					      * then 1 indirection block,
					      * then 1 double indirection block,
					      * then 1 triple indirection block.
					      * Then maybe a "file generation number" ??
					      */
		/* devices */
		dev_t i_rdev;
		/* named pipes on Coherent */
		struct {
			char p_addp[30];
			short p_pnc;
			short p_prx;
			short p_pwx;
		} i_p;
	} i_a;
	unsigned long i_atime;	/* time of last access */
	unsigned long i_mtime;	/* time of last modification */
	unsigned long i_ctime;	/* time of creation */
};

/* The admissible values for i_mode are listed in <linux/stat.h> :
 * #define S_IFMT  00170000  mask for type
 * #define S_IFREG  0100000  type = regular file
 * #define S_IFBLK  0060000  type = block device
 * #define S_IFDIR  0040000  type = directory
 * #define S_IFCHR  0020000  type = character device
 * #define S_IFIFO  0010000  type = named pipe
 * #define S_ISUID  0004000  set user id
 * #define S_ISGID  0002000  set group id
 * #define S_ISVTX  0001000  save swapped text even after use
 * Additionally for SystemV:
 * #define S_IFLNK  0120000  type = symbolic link
 * #define S_IFNAM  0050000  type = XENIX special named file ??
 * Additionally for Coherent:
 * #define S_IFMPB  0070000  type = multiplexed block device ??
 * #define S_IFMPC  0030000  type = multiplexed character device ??
 *
 * Since Coherent doesn't know about symbolic links, we use a kludgey
 * implementation of symbolic links: i_mode = COH_KLUDGE_SYMLINK_MODE
 * denotes a symbolic link. When a regular file should get this mode by
 * accident, it is automatically converted to COH_KLUDGE_NOT_SYMLINK.
 * We use S_IFREG because only regular files (and Coherent pipes...) can have
 * data blocks with arbitrary contents associated with them, and S_ISVTX
 * ("save swapped text after use") because it is unused on both Linux and
 * Coherent: Linux does much more intelligent paging, and Coherent hasn't
 * virtual memory at all.
 * Same trick for Xenix.
 */
#define COH_KLUDGE_SYMLINK_MODE	(S_IFREG | S_ISVTX)
#define COH_KLUDGE_NOT_SYMLINK	(S_IFREG | S_ISVTX | S_IRUSR) /* force read access */
extern inline mode_t from_coh_imode(unsigned short mode)
{
	if (mode == COH_KLUDGE_SYMLINK_MODE)
		return (S_IFLNK | 0777);
	else
		return mode;
}
extern inline unsigned short to_coh_imode(mode_t mode)
{
	if (S_ISLNK(mode))
		return COH_KLUDGE_SYMLINK_MODE;
	else if (mode == COH_KLUDGE_SYMLINK_MODE)
		return COH_KLUDGE_NOT_SYMLINK;
	else
		return mode;
}

/* Admissible values for i_nlink: 0.._LINK_MAX */
#define XENIX_LINK_MAX	126	/* ?? */
#define SYSV_LINK_MAX	126	/* 127? 251? */
#define COH_LINK_MAX	10000	/* max number of hard links to an inode */

/* The number of inodes per block is
   sb->sv_inodes_per_block = block_size / sizeof(struct sysv_inode) */
/* The number of indirect pointers per block is
   sb->sv_ind_per_block = block_size / sizeof(unsigned long) */


/* SystemV/Coherent directory entry on disk */

#define SYSV_NAMELEN	14	/* max size of name in struct sysv_dir_entry */

struct sysv_dir_entry {
	sysv_ino_t inode;
	char name[SYSV_NAMELEN]; /* up to 14 characters, the rest are zeroes */
};

#define SYSV_DIRSIZE	sizeof(struct sysv_dir_entry)	/* size of every directory entry */


/* Operations */
/* ========== */


/* identify the FS in memory */
#define FSTYPE_XENIX	1
#define FSTYPE_SYSV4	2
#define FSTYPE_SYSV2	3
#define FSTYPE_COH	4

#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)

/* Because the block size may be smaller than 1024 (which is the unit used by
   the disk drivers and the buffer code), many functions must return a pointer
   to the buffer data additionally to the buffer head pointer.
*/
#if 0
struct bh_data {
	struct buffer_head * bh;
	char * bh_data;
};
#endif

/* sysv_bread(sb,dev,block,...) would be equivalent to
   bread(dev,block,BLOCK_SIZE)
   if the block size were always 1024, which is the only one bread() supports.
*/
static inline struct buffer_head *
sysv_bread (struct super_block *sb, int dev, unsigned int block, char* * data)
{
	struct buffer_head *bh;

	if (!(bh = bread (dev, (block >> sb->sv_block_size_ratio_bits) + sb->sv_block_base, BLOCK_SIZE)))
		return NULL;
	*data = bh->b_data + ((block & sb->sv_block_size_ratio_1) << sb->sv_block_size_bits);
	return bh;
}


/* locks - protect against simultaneous write and truncate */

extern void _coh_wait_on_inode (struct inode * inode);

extern inline void coh_wait_on_inode (struct inode * inode)
{
	if (inode->u.sysv_i.i_lock)
		_coh_wait_on_inode(inode);
}

extern inline void coh_lock_inode (struct inode * inode)
{
	if (inode->u.sysv_i.i_lock)
		_coh_wait_on_inode(inode);
	inode->u.sysv_i.i_lock = 1;
}

extern inline void coh_unlock_inode (struct inode * inode)
{
	inode->u.sysv_i.i_lock = 0;
	wake_up(&inode->u.sysv_i.i_wait);
}


/*
 * Function prototypes
 */

extern int sysv_lookup(struct inode * dir,const char * name, int len,
	struct inode ** result);
extern int sysv_create(struct inode * dir,const char * name, int len, int mode,
	struct inode ** result);
extern int sysv_mkdir(struct inode * dir, const char * name, int len, int mode);
extern int sysv_rmdir(struct inode * dir, const char * name, int len);
extern int sysv_unlink(struct inode * dir, const char * name, int len);
extern int sysv_symlink(struct inode * inode, const char * name, int len,
	const char * symname);
extern int sysv_link(struct inode * oldinode, struct inode * dir, const char * name, int len);
extern int sysv_mknod(struct inode * dir, const char * name, int len, int mode, int rdev);
extern int sysv_rename(struct inode * old_dir, const char * old_name, int old_len,
	struct inode * new_dir, const char * new_name, int new_len);
extern struct inode * sysv_new_inode(const struct inode * dir);
extern void sysv_free_inode(struct inode * inode);
extern unsigned long sysv_count_free_inodes(struct super_block *sb);
extern int sysv_new_block(struct super_block * sb);
extern void sysv_free_block(struct super_block * sb, unsigned int block);
extern unsigned long sysv_count_free_blocks(struct super_block *sb);

extern int sysv_bmap(struct inode *,int);

extern struct buffer_head * sysv_getblk(struct inode *, unsigned int, int, char* *);
extern struct buffer_head * sysv_file_bread(struct inode *, int, int, char* *);

extern void sysv_truncate(struct inode *);
extern void sysv_put_super(struct super_block *);
extern struct super_block *sysv_read_super(struct super_block *,void *,int);
extern void sysv_write_super(struct super_block *);
extern void sysv_read_inode(struct inode *);
extern int sysv_notify_change(int,struct inode *);
extern void sysv_write_inode(struct inode *);
extern void sysv_put_inode(struct inode *);
extern void sysv_statfs(struct super_block *, struct statfs *);
extern int sysv_sync_inode(struct inode *);
extern int sysv_sync_file(struct inode *, struct file *);
#if 0
extern int sysv_mmap(struct inode *, struct file *, unsigned long, size_t, int, unsigned long);
#endif

extern struct inode_operations sysv_file_inode_operations;
extern struct inode_operations sysv_file_inode_operations_with_bmap;
extern struct inode_operations sysv_dir_inode_operations;
extern struct inode_operations sysv_symlink_inode_operations;

#endif