Rename the normalize_mounts() helper to drop_unused_mounts. All the
helpers called in there get rid of mounts that are unused for a variety
of reasons. And whereas the helpers are aptly prefixed with "drop" the
overall helper isn't and instead uses "normalize".
Make it more obvious what the helper actually does by renaming it from
normalize_mounts() to drop_unused_mounts(). Readers of code calling this
helper will immediately see that it will get rid of unused mounts.
Link: https://github.com/systemd/systemd/issues/22206
If a service requests both ProtectSubset=pid and ProtectHostname=true
then it will currently fail to start. The ProcSubset=pid option
instructs systemd to mount procfs for the service with subset=pid which
hides all entries other than /proc/<pid>. Consequently trying to
interact with the two files /proc/sys/kernel/{hostname,domainname}
covered by ProtectHostname=true will fail.
Fix this by only performing this check when ProtectSubset=pid is not
requested. Essentially ProtectSubset=pid implies/provides
ProtectHostname=true.
Christian Brauner