[OpenAFS-devel] afs and byte-range locking ideas

[Nathan Neulinger]

> Unfortunately, you're not only glossing over all the problems with having
> the server keep lock state (most of which are not insurmountable); you're
> also missing a fundamental problem.  If you allow multiple hosts to hold
> byte-range locks at the same time, then applications on those hosts will
> try to write the file at the same time.  The result will be a mess, since
> the applications think they have locked the parts of the file they're
> updating but the whole-file last-write semantics of AFS mean they really
> don't.

So what you're saying is - with the way afs is designed, multiple
clients can NEVER safely modify a file simultaneously, even if those
clients are accessing completely separate ranges of the file? So even if
the one client only sent a single block worth of writes to the file on
the server, that cannot be relied upon by other clients?

I guess what that implies is that the stage 1 (client side only
upgradable locks) are the best that we can do without completely
changing the way afs works. That would be an improvement - at least apps
on the same box can have fully functional locking support.

-- Nathan