Ubuntu for Windows: Mounting C: Drive to WSL's Root

persistent_c_mount_wsl.sh

# allow `mount` cmd without password
echo "$USER ALL=NOPASSWD: /bin/mount" | (sudo su -c 'EDITOR="tee -a" visudo')
# add the mount directive to `fstab`
sudo mkdir -p /c
sudo sh -c "echo '/mnt/c /c none bind' >> /etc/fstab"
# update to `.bashrc` to auto mount at login
echo "sudo mount -a" >> ~/.bashrc
# now reload it
source ~/.bashrc

FYI this is now possible to do it with wsl.conf https://docs.microsoft.com/en-us/windows/wsl/wsl-config
root = /

diego@diego-thinkpad:~$ cat /etc/wsl.conf
# Enable extra metadata options by default
[automount]
enabled = true
root = /
options = "metadata,umask=22,fmask=11"
mountFsTab = false

# Enable DNS – even though these are turned on by default, we’ll specify here just to be explicit.
[network]
generateHosts = true
generateResolvConf = true

diego@diego-thinkpad:~$ mount -l | grep drvfs
C: on /c type drvfs (rw,noatime,uid=1000,gid=1000,umask=22,fmask=11,metadata)
diego@diego-thinkpad:~$

Works for me (wsl 1, Win 10 pro, Version 10.0.18363.1500, Ubuntu 20.04.2 LTS)