Rewrite ioctl entry and its relate function.  This patch fix ioctl data
read/write error and change data I/O access from byte to Dword.
Signed-off-by: NChing Huang <ching2048@areca.com.tw>
Reviewed-by: NTomas Henzl <thenzl@redhat.com>
Signed-off-by: NChristoph Hellwig <hch@lst.de>