2007-12-19

这个模块提供管理file的一些接口函数.
struct file {
	struct list_head	f_list;  /*组织: annon_list 或者 free_list ( 在使用中|不在使用中)*/
	struct dentry		*f_dentry;/*组织*/ 
	struct vfsmount         *f_vfsmnt;/*组织*/
        struct file_operations	*f_op;    /*feature*/
	atoic_t		f_count;  /*feature*/	
        unsigned int 		f_flags;
	mode_t			f_mode;
	loff_t			f_pos;
	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;
};

两个链表:
/* Here the new files go */
static LIST_HEAD(anon_list);  /*匿名的....为啥叫匿名,看看dentry_open就知道了,正常的file会链接进
                                  inode->i_sb->s_files*/
/* And here the free ones sit */
static LIST_HEAD(free_list);
/* public *and* exported. Not pretty! */
spinlock_t files_lock = SPIN_LOCK_UNLOCKED;


有个分配和释放的几个接口函数:
struct file * get_empty_filp(void)
void fput(struct file * file)
struct file * fget(unsigned int fd)
void put_filp(struct file *file) /*不调用file->f_op->release(inode, file);*/

分配策略:
  预留10个(NR_RESERVED_FILES)file结构(即free_list中总有至少10个备用),然后总的数量不超过一个最大值(可配).说他简单是
因为,一旦分配就不再释放了,也不提供shrink操作....嘿嘿,有点像dquota.


void file_move(struct file *file, struct list_head *list) 
void file_moveto(struct file *new, struct file *old)
int fs_may_remount_ro(struct super_block *sb) /*如果要吧文件系统重新安装成read only,
                                                    就需要看看有没有写操作在执行*/


如果还需要什么分析的话,..... 我晕倒....