Re: nfs cache bug (when server delete the file ,nfs client can read file also)

["bfields@fieldses.org" <bfields@fieldses.org>]

On Fri, Nov 23, 2012 at 02:00:13PM +0800, fanchaoting wrote:
> Myklebust, Trond 写道:
> > On Fri, 2012-11-23 at 13:23 +0800, fanchaoting wrote:
> >> Myklebust, Trond 写道:
> >>> On Fri, 2012-11-23 at 12:18 +0800, fanchaoting wrote:
> >>>> I think  when the nfs server delete the file ,
> >>>> the  server should notice the nfs client,
> >>>> but the upstream kernel does't this.
> >>> So is this a problem with the client or the server? In other words, if
> >>> you use a different server/client combination, do you see a different
> >>> result?
> >>>
> >> I think that the server has the problem .when the server deletes the file ,
> >> it should notice the client immediately.
> > 
> > There is no notification mechanism in NFS; on open(), the client is
> > supposed to revalidate its cached information and the server is supposed
> > to return an ESTALE error if the filehandle is no longer valid. Either
> > one of these 2 mechanisms (client revalidation or server reply) could be
> > going wrong here, which is why I'm asking.
> 
> I found J. Bruce Fields's patch(break delegations on unlink)  maybe solve this problem .
> But I did't found it in the upstream kernel.

Yes, still working on getting that merged.  Next step is probably to
rebase it on top of jlayton's ESTALE patches, assuming those will go in
first.  In theory they could make 3.8 but that may be optimistic.

--b.