On Tue, 17 May 2022, Trond Myklebust wrote:
> On Tue, 2022-05-17 at 10:05 +1000, NeilBrown wrote:
> >
> > Hi,
> > any thoughts on these patches?
>
>
> To me, this problem is simply not worth breaking hot path functionality
> for. If the credential changes on the server, but not on the client (so
> that the cred cache comparison still matches), then why do we care?
>
> IOW: I'm a NACK until convinced otherwise.
In what way is the hot path broken? It only affect a permission test
failure. Why is that considered "hot path"??
RFC 1813 says - for NFSv3 at least -
The information returned by the server in response to an
ACCESS call is not permanent. It was correct at the exact
time that the server performed the checks, but not
necessarily afterwards. The server can revoke access
permission at any time.
Clearly the server can allow allow access at any time.
This seems to argue against caching - or at least against relying too
heavily on the cache.
RFC 8881 has the same text for NFSv4.1 - section 18.1.4
"why do we care?" Because the server has changed to grant access, but
the client is ignoring the possibility of that change - so the user is
prevented from doing work.
NeilBrown
