Closes: #2085.
- Read the list of snapshots and properly determine the full subvolume name to
be used for mounting the .snapshots subvolume.
- Use systemd .mount units instead of editing fstab. Fstab editing is dangerous
and could result in system not booting properly. systemd units are better suited
for tool based editing while /etc/fstab is recommended for humans.
- Use automount feature provided by systemd using autofs to perform mounting. This
means that the backing filesystem is only accessed and mounted when the mount
point is accessed by a program. Parse errors in the mount/automount file and
incorrect mount parameters are also tolerated well with failure to boot.
Tests:
- On a fresh Debian Bullseye install with btrfs. Install FreedomBox with the
changes, create and delete manual snapshots. Rollback to a snapshot should also
work. /.snapshots should contain all the files inside each of the snapshots.
- After rebooting into a rolled back snapshot, create/delete and restore to a
snapshot should work. /.snapshots should contain all the files inside each of
the snapshots.
- Introduce an error in .mount file such the mount operation will fail. Reboot
the machine. Reboot is successful. /.snapshots is still mounted as autofs.
Trying to access /.snapshots will result in error during mount operation.
- On a vagrant box without changes. Install freedombox and ensure snapshot app
setup has been run. This creates the /etc/fstab entry. Apply the patches.
snapshot app will run and remove the mount line in /etc/fstab and create the
.mount entry. /.snapshots is still mounted but not because of .automount. After
reboot, /.snapshots is mounted with autofs and also with btrfs. Unmounting
/.snapshots and then trying to run 'ls /.snapshots' will perform the mount again.
Signed-off-by: Sunil Mohan Adapa <sunil@medhas.org>
Reviewed-by: James Valleroy <jvalleroy@mailbox.org>
