systemd-fsck@.service, systemd-fsck-root.service, systemd-fsck — File system checker logic
systemd-fsck@.service
systemd-fsck-root.service
/usr/lib/systemd/systemd-fsck
systemd-fsck@.service is a
                service responsible for file system checks. It is
                instantiated for each device that requires a file
                system
                check. systemd-fsck-root.service is
                responsible for file system checks on the root
                file system.
systemd-fsck will
                forward file system checking progress to the
                console. If a file system check fails emergency mode
                is activated, by isolating to
                emergency.target.
systemd-fsck understands
                one kernel command line parameter:
fsck.mode=¶One of
                                auto,
                                force,
                                skip. Controls the
                                mode of operation. The default is
                                auto, and ensures
                                that file system checks are done when
                                the file system checker deems them
                                necessary. force
                                unconditionally results in full file
                                system checks. skip
                                skips any file system
                                checks.