Re: [PATCH 1/1] NFSD: fix error handling in callbacks

[Trond Myklebust <trondmy@hammerspace.com>]

On Tue, 2021-03-09 at 10:37 -0500, J. Bruce Fields wrote:
> On Tue, Mar 09, 2021 at 09:41:27AM -0500, Olga Kornievskaia wrote:
> > From: Olga Kornievskaia <kolga@netapp.com>
> > 
> > When the server tries to do a callback and a client fails it due to
> > authentication problems, we need the server to set callback down
> > flag in RENEW so that client can recover.
> 
> I was looking at this.  It looks to me like this should really be
> just:
> 
>         case 1:
>                 if (task->tk_status)
>                         nfsd4_mark_cb_down(clp, task->tk_status);
> 
> If tk_status showed an error, and the ->done method doesn't return 0
> to
> tell us it something worth retrying, then the callback failed
> permanently, so we should mark the callback path down, regardless of
> the
> exact error.

I disagree. task->tk_status could be an unhandled NFSv4 error (see
nfsd4_cb_recall_done()). The client might, for instance, be in the
process of returning the delegation being recalled. Why should that
result in the callback channel being marked as down?

> 
> --b.
> 
> > 
> > Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
> > ---
> >  fs/nfsd/nfs4callback.c | 1 +
> >  1 file changed, 1 insertion(+)
> > 
> > diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c
> > index 052be5bf9ef5..7325592b456e 100644
> > --- a/fs/nfsd/nfs4callback.c
> > +++ b/fs/nfsd/nfs4callback.c
> > @@ -1189,6 +1189,7 @@ static void nfsd4_cb_done(struct rpc_task
> > *task, void *calldata)
> >                 switch (task->tk_status) {
> >                 case -EIO:
> >                 case -ETIMEDOUT:
> > +               case -EACCES:
> >                         nfsd4_mark_cb_down(clp, task->tk_status);
> >                 }
> >                 break;
> > -- 
> > 2.27.0
> > 
> 

-- 
Trond Myklebust
Linux NFS client maintainer, Hammerspace
trond.myklebust@hammerspace.com