I have an external disk connected via USB that was accidentally disconnected uncleanly. Now
lsing the directory in which it was mounted gives
umounting the directory simply hangs. dmesg just contains:
[3360010.363235] usb 2-1.1: USB disconnect, device number 3
How do I resolve this (short of rebooting), i.e. how do I clean up kernel state upon unclean disconnect of an external storage device?