systemd-remount-fs and ConditionKernelCommandLine=!rw

[Etienne Champetier <champetier.etienne@xxxxxxxxx>]

Hello,

If we have `rw` kargs, is systemd-remount-fs.service actually needed ?

For context when using anaconda to install an rpm-ostree based system,
you get an entry in fstab for `/` with option `defaults`. When trying
to switch to composefs, / can only be readonly (composefs), so
systemd-remount-fs.service fails remounting rw.

The approach for now is to have a service that edit /etc/fstab [1][2],
but maybe we can just skip running systemd-remount-fs entirely.
Another approach could also be to avoid remouting only in some cases [3].

[1] https://github.com/ostreedev/ostree/pull/3372
[2] https://github.com/containers/bootc/pull/417
[3] https://github.com/ostreedev/ostree/issues/3193#issuecomment-2585208820

Best
Etienne