Question about linux filesystem and psql

Is it possible to keep data safe with linux and psql after crash?

The short description of the scenario is:
-> writing data with psql (using transactions), store process completed
-> user hits the reset button or kernel crashes (whatever left the filesystem
unsynced)
-> filesystem is xfs or reiserfs
-> reboot causes some blocks filled with zero (journalling feature discussed
on lkml) of last accessed files from some applications

My questions are:
Is there any solution that psql keeps the database intact (already written
data)?
Is there an option for psql or filesystem (like reiserfs data=ordered) which
should be used  (maybe backup database)

Thanks

Marcus