关于多设备挂载的问题（在原有的基础上挂载U盘设备）

发布于 2012-05-03 15:30:20 浏览：4186 订阅该版

```if (dfs_mount("sd0", "/", "elm", 0, 0) == 0)
		{
			rt_kprintf("File System initialized!
");
		}
		else
			rt_kprintf("File System initialzation failed!
");

ret = mkdir("/udisk", 0x777);	 
if(ret < 0)
{

rt_kprintf("[mkdir error!]
");
}
else
{ 
rt_kprintf("[mkdir ok!]
");
}

if (dfs_mount("usb", "/udisk", "elm", 0, 0) == 0)
		{
			rt_kprintf("File System initialized!
");
		}
		else
			rt_kprintf("File System initialzation failed!
");

fd = open("/udisk/text1.txt", O_WRONLY | O_CREAT | O_TRUNC,0);
if (fd >= 0)
{
	close(fd);
}```
为什么我的第二次挂载的成功必须要修改底层的如下函数中的sector*512,count*512呢？求解
```DRESULT disk_read(BYTE drv, BYTE *buff, DWORD sector, BYTE count)
{	
rt_size_t result;	
rt_device_t device = disk[drv];	
result = rt_device_read(device, sector*512, buff, count*512);	
if (result ==count*512)	
{		return RES_OK;
}	
return RES_ERROR;
}

DRESULT disk_write(BYTE drv, const BYTE *buff, DWORD sector, BYTE count)
{	
rt_size_t result;	
rt_device_t device = disk[drv];	
result = rt_device_write(device, sector*512, buff, count*512);	
if (result == count*512)	
{		return RES_OK;	
}	
return RES_ERROR;
}```