Re: [PATCH 0/3] fix backchannel crash due to multipath

["J. Bruce Fields" <bfields@fieldses.org>]

On Mon, Jun 13, 2016 at 07:24:06PM +0000, Trond Myklebust wrote:
> 
> 
> On 6/13/16, 14:21, "J. Bruce Fields" <bfields@fieldses.org> wrote:
> 
> >On March 24 J. Bruce Fields said:
> >> pynfs can crash the nfs server since the new multipath code.  The
> >> problem is that pynfs uses the same tcp connection for multiple v4
> >> clients (something the spec explicitly allows).  The callback client in
> >> such cases has to share the same rpc_xprt.  The new rpc code, when it
> >> creates two callback clients sharing the same rpc_xprt, ends up trying
> >> to keep that rpc_xprt on the lists of two different rpc_xprt_switch's.
> >> The first symptom I see is a list corruption warning.
> >>
> >> So, I'm enforcing the requirement that there be only one backchannel
> >> rpc_xprt_switch per tcp connection by doing as we do in the rpc_xprt
> >> case: keeping a pointer to it in the svc_xprt, and using that when it's
> >> available instead of allocating a new one.
> >
> >> That's a pretty straightforward fix (and I've verified it works), but
> >> doesn't look very elegant.  If there's a better solution, I'm all ears.
> >
> >I haven't come up with anything neater, and kind of need the crash
> >fixed.  ACK or NACK?  I can take it through my tree if it's an ACK.
> >
> >--b.
> >
> 
> Ack

Thanks!--b.