Problem:
I mounted a disk from a remote Linux server and was able to use it. After a while, it stopped working. I am guessing this might be because the connection timed out. I was not able to ls that drive anymore. So I tried to unmount it using:
fusermount -u /tmp/mymountpoint/
But it failed with the error:
fusermount: mount failed: Device or resource busy
But using the below command, I was able to force the unmount successfully:
umount -l /tmp/mymountpoint/