This is especially important for distributions like NixOS where `/bin/bash` doesn't exist, or for MacOS users who've installed a newer version of Bash than the one that comes with their OS.
Signed-off-by: Andrew "Tianon" Page <admwiggin@gmail.com>
Previously, when the graphdir was a root of a mountpoint, we would not
be able to cleanup the graphdir, as the script would umount in case
target dir is a mount itself
```/etc/mtab
/dev/xvdc1 /var/lib/docker btrfs
```
When running the script, the graphdir would be unmounted and it would
remove a (possibly) empty folder.
```
Nuking /var/lib/docker ...
(if this is wrong, press Ctrl+C NOW!)
+ sleep 10
+ umount -f /var/lib/docker
+ rm -rf /var/lib/docker
```
This PR includes the necessary changes to nuke the folder on this
scenario, including when the graphdir is a btrfs mount iself.
Signed-off-by: Bruno Tavares <btavare@thoughtworks.com>
This change allows btrfs subvolumes to be found in additional system
configurations. The old logic failed to correctly identify subvolumes
when the root fs was mounted as a subvolume that was not the btrfs
filesystem root.
Signed-off-by: Adam Mills <adam@armills.info>
