Put a timeout on -ve name cache entries in NFS

[Rick Macklem]

On Thu, 22 Oct 2009, Bruce Evans wrote:

>
> One reason that I never committed my port of NetBSD's implementation of
> negative cache entries for nfs is that I thought the timeout should be
> a mount option but I didn't want to deal with the portability problems
> from that.
>
Just to clarify. Are you saying that, given no other system has such
a mount option, you think the sysctl variable is an ok solution or
that you think it should be a mount option and not a sysctl variable?

I'll admit that I'm biased because the sysctl variable is easier to
do (and I don't think many people will need to twiddle it). I suggested
it to John, mostly so that there was a way of disabling the -ve name
caching, for the rare case where it might be causing someone grief.
(That's what I think he meant by "safety belt".)

rick