mount: wrong fs type, bad option, bad superblock on 125.64.41.244:/data/img,
missing codepage or helper program, or other error
(for several filesystems (e.g. nfs, cifs) you might
need a /sbin/mount.<type> helper program)
In some cases useful info is found in syslog - try
dmesg | tail or so
apt-get install nfs-common
或者
yum install nfs-utils
sudo umount /mnt/
/mnt was not found in /proc/mounts
/mnt was not found in /proc/mounts
解决：
umount 时使用 -l 命令。
$ sudo umount -l /mnt/