Indeed. update calls bdflush(2)'s function 1 to sync_old_buffers. Actually
it would only call sync(2) as a fallback if this call to bdflush(2)
failed (note : I may seem to have written something different earlier
in this thread. I read the sources more thouroughly since then :-) ).
> (this one hasn't changed). So which one is more bdflush?
Considering the comments in fs/buffer.c, I would say the answer is
kflushd : bdflush(2)'s function 1 only calls sync_old_buffers,
which has the comment "this function is essentially \"update\"" ;
bdflush() (the routine that constitutes the kflushd thread) also
has the mention "This is the actual bdflush daemon itself."
-- Thomas.Quinot@Cuivre.FdN.FR <URL:http://Web.FdN.FR/~tquinot/>