Any drive of any filesystem that is already mounted under Windows can be then mounted under WSL. What makes this possible is a filesystem plugin in WSL named DrvFS.
C: drive is mounted by default under WSL at
To mount a different drive under WSL, create a directory under
/mnt and mount using the DrvFS plugin using this syntax:
$ mkdir /mnt/k $ sudo mount -t drvfs K: /mnt/k
$ cat /etc/mtab
$ sudo umount /mnt/k