fs.h.txt

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相关文件：
	/fs/block_dev.c
	/fs/buffer.c



struct super_block {
        struct list_head        s_list;         //连接所有的super_block结构
        kdev_t                  s_dev;
        unsigned long           s_blocksize;		//块大小
        unsigned char           s_blocksize_bits;	
        unsigned char           s_dirt;
        unsigned long long      s_maxbytes;     /* 文件的最大长度 字节计算 */
        struct file_system_type *s_type;	//文件类型
        struct super_operations *s_op;
        struct dquot_operations *dq_op;
        unsigned long           s_flags;
        unsigned long           s_magic;	//文件魔数
        struct dentry           *s_root;
        struct rw_semaphore     s_umount;
        struct semaphore        s_lock;
        int                     s_count;
        atomic_t                s_active;

        struct list_head        s_dirty;        /* dirty inodes */
        struct list_head        s_locked_inodes;/* inodes being synced */
        struct list_head        s_files;

        struct block_device     *s_bdev;
	struct list_head        s_instances;
        struct quota_info s_dquot;      /* Diskquota specific options */

        union {
                struct minix_sb_info    minix_sb;
                struct ext2_sb_info     ext2_sb;	//各种文件系统的联合
                struct ext3_sb_info     ext3_sb;
		……
       	} u;
        struct semaphore s_vfs_rename_sem;      /* Kludge */
        struct semaphore s_nfsd_free_path_sem;
};


struct nameidata {
        struct dentry *dentry;	//路径名称所对应的dentry结构，也就是这个路径的换存
        struct vfsmount *mnt;	//这个路径所对应的文件系统的vfsmount结构(如果有一个文件系统安装的话)
        struct qstr last;
        unsigned int flags;
        int last_type;
};


struct file {
        struct list_head        f_list;
        struct dentry           *f_dentry;
        struct vfsmount         *f_vfsmnt;
        struct file_operations  *f_op;
        atomic_t                f_count;
        unsigned int            f_flags;
        mode_t                  f_mode;
        loff_t                  f_pos;	//文件的读写指针（？）
        unsigned long           f_reada, f_ramax, f_raend, f_ralen, f_rawin;	
        struct fown_struct      f_owner;
        unsigned int            f_uid, f_gid;
        int                     f_error;

        unsigned long           f_version;

        /* needed for tty driver, and maybe others */
        void                    *private_data;

        /* preallocated helper kiobuf to speedup O_DIRECT */
        struct kiobuf           *f_iobuf;
        long                    f_iobuf_lock;
};


//这个结构主要用于描述inode节点的状态的
struct inodes_stat_t {	
        int nr_inodes;	//inode节点的总数量
        int nr_unused;	//没有使用的inode节点的数目
        int dummy[5];
};
extern struct inodes_stat_t inodes_stat;


struct inode {
	struct list_head	i_hash;
	struct list_head	i_list;
	struct list_head	i_dentry;
	
	struct list_head	i_dirty_buffers;
	struct list_head	i_dirty_data_buffers;

	unsigned long		i_ino;		//标志inode的唯一号码
	atomic_t		i_count;	//访问计数
	kdev_t			i_dev;		//所在的设备
	umode_t			i_mode;
	nlink_t			i_nlink;
	uid_t			i_uid;
	gid_t			i_gid;
	kdev_t			i_rdev;
	loff_t			i_size;		//文件的当前大小
	time_t			i_atime;	//最后一次访问时间
	time_t			i_mtime;	//最后一次修改时间
	time_t			i_ctime;	//最初创建时间
	unsigned int		i_blkbits;
	unsigned long		i_blksize;
	unsigned long		i_blocks;
	unsigned long		i_version;
	unsigned short		i_bytes;
	struct semaphore	i_sem;
	struct semaphore	i_zombie;
	struct inode_operations	*i_op;		//inode操作函数集
	struct file_operations	*i_fop;		//对应的文件操作集
	struct super_block	*i_sb;
	wait_queue_head_t	i_wait;
	struct file_lock	*i_flock;
	struct address_space	*i_mapping;	//这个指针就是指向下面的i_data属性
	struct address_space	i_data;		//主要的文件缓冲操作属性
	struct dquot		*i_dquot[MAXQUOTAS];
	/* These three should probably be a union */
	struct list_head	i_devices;
	struct pipe_inode_info	*i_pipe;
	struct block_device	*i_bdev;
	struct char_device	*i_cdev;
	unsigned long		i_dnotify_mask; /* Directory notify events */
	struct dnotify_struct	*i_dnotify; /* for directory notifications */

	unsigned long		i_state;

	unsigned int		i_flags;
	unsigned char		i_sock;

	atomic_t		i_writecount;
	unsigned int		i_attr_flags;
	__u32			i_generation;
	union {
		struct minix_inode_info		minix_i;
		struct ext2_inode_info		ext2_i;
		struct ext3_inode_info		ext3_i;
		struct hpfs_inode_info		hpfs_i;
		struct ntfs_inode_info		ntfs_i;
		struct msdos_inode_info		msdos_i;
		struct umsdos_inode_info	umsdos_i;
		……
	}u;
}

struct address_space {
	struct list_head	clean_pages;	/* list of clean pages */
	struct list_head	dirty_pages;	/* list of dirty pages */
	struct list_head	locked_pages;	/* list of locked pages */
	unsigned long		nrpages;	/* number of total pages */
	struct address_space_operations *a_ops;	/* methods */
	struct inode		*host;		/* owner: inode, block_device */
	struct vm_area_struct	*i_mmap;	/* list of private mappings */
	struct vm_area_struct	*i_mmap_shared; /* list of shared mappings */
	spinlock_t		i_shared_lock;  /* and spinlock protecting it */
	int			gfp_mask;	/* how to allocate the pages */
};





**************************基本数据结构***************************
(1)struct block_device_operations {
        int (*open) (struct inode *, struct file *);
        int (*release) (struct inode *, struct file *);
        int (*ioctl) (struct inode *, struct file *, unsigned, unsigned 						long);
        int (*check_media_change) (kdev_t);
        int (*revalidate) (kdev_t);
   };
这个结构用于块设备blkdevs(block_dev.c中)的操作，从2.4以后，不再有write,read等操作。


(2)struct buffer_head {
	struct buffer_head *b_next;     /* Hash 请求链表的连接指针 */
	unsigned long b_blocknr;	/* 在设备上的块号 */
	unsigned short b_size;		/* 块大小 */
	unsigned short b_list;		/* List that this buffer appears */
	kdev_t b_dev;			/* 设备号 (B_FREE = free) */

	atomic_t b_count;		/* 用户使用计数 */
        kdev_t b_rdev;                  /* 真实的设备 */
        unsigned long b_state;          /* buffer state bitmap (see above) */
        unsigned long b_flushtime;      /* Time when (dirty) buffer should be witten */

        struct buffer_head *b_next_free;/* lru/free list linkage */
        struct buffer_head *b_prev_free;/* doubly linked list of buffers */
        struct buffer_head *b_this_page;/* 一个环形指针链，用来连接在一个内存页面中的buffer */
        struct buffer_head *b_reqnext;  /* request queue */

        struct buffer_head **b_pprev;   /* doubly linked list of hash-queue */
        char * b_data;                  /* pointer to data block */
        struct page *b_page;            /* 这个buffer所在的那个内存页面的结构 */
        void (*b_end_io)(struct buffer_head *bh, int uptodate); /* I/O completin */
        void *b_private;                /* reserved for b_end_io */
        unsigned long b_rsector;        /* Real buffer location on disk */
        wait_queue_head_t b_wait;

        struct inode *       b_inode;
        struct list_head     b_inode_buffers;   /* doubly linked list of inode dirty buffers */
};


*****************************************************************


***************************buffer基本定义************************
这里定义的这些类型，是用于/fs/buffer.c中的，用来定义buffer的种类。
#define BUF_CLEAN0
#define BUF_LOCKED      1   /* Buffers scheduled for write */
#define BUF_DIRTY       2   /* Dirty buffers, not yet scheduled for write */
#define BUF_PROTECTED   3   /* Ramdisk persistent storage */
#define NR_LIST         4

实际上以下的这些宏定义都是返回相应的buffer的状态
#define __buffer_state(bh,state) (((bh)->b_state & (1UL<<H_##state)) != 0)
#define buffer_uptodate(bh)     __buffer_state(bh,Uptodate)
#define buffer_dirty(bh)        __buffer_state(bh,Dirty)
#define buffer_locked(bh)       __buffer_state(bh,Lock)
#define buffer_req(bh)          __buffer_state(bh,Req)
#define buffer_mapped(bh)       __buffer_state(bh,Mapped)
#define buffer_new(bh)          __buffer_state(bh,New)
#define buffer_protected(bh)    __buffer_state(bh,Protected)

#define BH_Uptodate     0       /* 1 如果buffer包含有效数据*/
#define BH_Dirty        1       /* 1 如果buffer脏 */
#define BH_Lock         2       /* 1 如果buffer被锁定*/
#define BH_Req          3       /* 0 如果buffer已经无效 */
#define BH_Mapped       4       /* 1 如果buffer有disk mapping */
#define BH_New          5       /* 1 如果buffer是新的并且没有被写过*/
以上的一组定义的作用是buffer的一系列状态
*****************************************************************

*********************读写状态的定义******************************
#define READ 0		//读命令
#define WRITE 1		//写命令
#define READA 2
*****************************************************************

*********************buffer的状态设置*****************************
static inline void mark_buffer_uptodate(struct buffer_head * bh, int on)
        if (on)	
                set_bit(BH_Uptodate, &bh->b_state);
        else
                clear_bit(BH_Uptodate, &bh->b_state);
	对bh按照参数进行设置

******************************************************************