Features:
+* create a btrfs qgroup for /var/lib/machines, and add all container
+ subvolumes we create to it.
+
+* nspawn: add --overlay= to support overlay file systems, similar to
+ --tmpfs= and --bind=.
+
* When logging about multiple units (stopping BoundTo units, conflicts, etc.),
log both units as UNIT=, so that journalctl -u triggers on both.
* Introduce $LISTEN_NAMES to complement $LISTEN_FDS, containing a
colon separated list of identifiers for the fds passed.
-* networkd: implement BindCarrier= logic to .network units that binds
- application of the file to the carrier sense on another interface,
- in order to implement uplink/downlink logic.
-
* when the fstab-generator runs in the initrd, it should create a /dev/null mask for systemd-fsck-root.service, to avoid that the the root fs is fsck'ed twice.
* maybe introduce WantsMountsFor=? Usecase:
* "machinectl commit" that takes a writable snapshot of a tree, invokes a shell in it, and marks it read-only after use
-* add transparent btrfs pool in a loopback file in /var if btrfs operations (such as systemd-import pull-dkr) are used and /var is not a btrfs file system
-
* systemd-nspawn -x should support ephemeral instances of gpt images
* hostnamectl: show root image uuid