umount_usb(){
    mnt=`df -h | grep /root/usb | wc -l`
    count=0
    while [ $mnt -eq 1 -a $count -le 5 ]
    do
	umount -f /root/usb/
	mnt=`df -h | grep /root/usb | wc -l`
	count=`expr $count + 1`
	sleep 1
	if [ $count -ge 5 ];then
	    exit
	fi
    done
}

umount_usb
if [ $1 == "ext4" ];then
    if [ -b /dev/sda1 ];then
    	echo -e "\ny" | mkfs.ext4 -T largefile /dev/sda1
	sleep 1
	mount -t ext4 /dev/sda1 /root/usb
    elif [ -b /dev/mmcblk0p6 ];then
	echo -e "\ny" | mkfs.ext4 -T largefile /dev/mmcblk0p6
	sleep 1
	mount -o rw,sync,barrier=0 /dev/mmcblk0p6 /root/usb
    fi
else
    mkfs.vfat -F 32 /dev/sda1
    sleep 1
    mount -t vfat /dev/sda1 /root/usb
fi