[OpenAFS-devel] Re: [OpenAFS] file timestamp difference

[Jeffrey Altman]

Jeffrey Hutzelman wrote:
> Note that on branches that include the NFS translator code, we need to
> be a bit more careful, as it's important that i_mtime.tv_nsec actually
> change when afs_sysnamegen changes, so that NFS clients will invalidate
> their DNLC when their sysname list changes.  Jeff's patch for 1.5.x does
> this currently, but it ignores the DV-based nsec that comes up from the
> VNOPS layer.  A version that wants to use that value would have to take
> both values into account.  It is probably safe to simply add them, or
> shift the usec left by 1000 and add sysnamegen mod 1000, or whatever. 
> The important things are that it changes when either DV or sysnamegen
> changes, and that it not go out of range.

Note that the original complaint was that the nanoseconds field as
reported on two different clients failed to match and that this was
causing synchronization problems for a distributed application.

My concern with the use of the sysnamegen hash as a means of fixing the
NFS translator issue is that it prevents a distributed application that
synchronizes on file timestamps to work on heterogeneous platforms.

I would like to try and find a solution for this case as well.  Since
the 1.4 branch doesn't support the NFS translator, we can apply one of
the fixes there without having a final solution for 1.5 and later.

Jeffrey Altman