Subject: RE: guard on SETATTR

From: "Noveck, Dave" <[email-masked]>
Date: Tue, 19 Jun 2001 10:00:23 -0700

Spencer Shepler wrote:
> Well, I know of two server implementations that currently do not meat
> your interpretation of the NFSv3 RFC (Solaris and AIX).  Has this been
> a problem for clients?  At least in my experience, I have not seen
> this as a problem.  It would be interesting to hear what other server
> implementations have done in this particular case.

It's not only my interpretation; it's fairly commonly held.  This started
when people asked me "Hey, why did V4 take out the atomic check that was
put into SETATTR for V3?"  Also, Salit's message on this topic assumed
that the check was atomic. 

WAFL makes this check atomically with the setattr and also does the entire
setattr atomically including any error cases or server failure.  The whole
thing is a transaction.  The spec clearly allows allows a partial SETATTR 
if one of the attributes is in error, so some of that is in the "extra
credit" category.  But as far as atomicity between the guard and setting 
the attributes goes, I always assumed that we were doing something that
was required.  So I'm suprised to hear that major V3 server implementations
don't do this atomically.