read_write.c.txt

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相关文件
	/fs/block_dev.c		//block_read(write)
	/drivers/block/ll_rw_blk.c

********************读写请求的入口***************************
struct file_operations def_blk_fops = {
        open:           blkdev_open,
        release:        blkdev_close,
        llseek:         block_llseek,
        read:           block_read,	//在这里，系统设置了读写入口	
        write:          block_write,	//在这里，系统设置了读写入口	
        fsync:          block_fsync,
        ioctl:          blkdev_ioctl,
};
*************************************************************


*******************读写的系统调用************************
(1)asmlinkage ssize_t sys_read(unsigned int fd, char * buf, size_t count)
	
(2)asmlinkage ssize_t sys_write(unsigned int fd, const char * buf, size_t count)
	file = fget(fd);	//显得到struct file结构指针
	struct inode *inode = file->f_dentry->d_inode;	//得到inode指针
	write = file->f_op->write)	//得到相应的读写函数的指针
	ret = write(file, buf, count, &file->f_pos);	//执行读写请求
*********************************************************