[systemd-devel] the need for a discoverable sub-volumes specification

[Chris Murphy]

How to do swapfiles?

Currently I'm creating a "swap" subvolume in the top-level of the file
system and /etc/fstab looks like this

UUID=$FSUUID    /var/swap               btrfs   noatime,subvol=swap 0 0
/var/swap/swapfile1 none swap defaults 0 0

This seems to work reliably after hundreds of boots.

a. Is this naming convention for the subvolume adequate? Seems like it
can just be "swap" because the GPT method is just a single partition
type GUID that's shared by multiboot Linux setups, i.e. not arch or
distro specific
b. Is the mount point, /var/swap, OK?
c. What should the additional naming convention be for the swapfile
itself so swapon happens automatically?


Also, instead of /@auto/ I'm wondering if we could have
/x-systemd.auto/ ? This makes it more clearly systemd's namespace, and
while I'm a big fan of the @ symbol for typographic history reasons,
it's being used in the subvolume/snapshot regimes rather haphazardly
for different purposes which might be confusing? e.g. Timeshift
expects subvolumes it manages to be prefixed with @. Meanwhile SUSE
uses @ for its (visible) root subvolume in which everything else goes.
And still ZFS uses @ for their (read-only) snapshots.

--
Chris Murphy