Re: [PATCH v3 3/3] nfsd: back channel stuck in SEQ4_STATUS_CB_PATH_DOWN

[Bruce Fields <bfields@fieldses.org>]

On Thu, Sep 16, 2021 at 07:00:20PM +0000, Chuck Lever III wrote:
> Bruce, Dai -
> 
> > On Sep 16, 2021, at 2:22 PM, Dai Ngo <dai.ngo@oracle.com> wrote:
> > 
> > When the back channel enters SEQ4_STATUS_CB_PATH_DOWN state, the client
> > recovers by sending BIND_CONN_TO_SESSION but the server fails to recover
> > the back channel and leaves it as NFSD4_CB_DOWN.
> > 
> > Fix by enhancing nfsd4_bind_conn_to_session to probe the back channel
> > by calling nfsd4_probe_callback.
> > 
> > Signed-off-by: Dai Ngo <dai.ngo@oracle.com>
> 
> I'm wondering if this one is appropriate to pull into v5.15-rc.

I think so.

Dai, do you have a pynfs test for this case?

--b.

> > ---
> > fs/nfsd/nfs4state.c | 16 +++++++++++++---
> > 1 file changed, 13 insertions(+), 3 deletions(-)
> > 
> > diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c
> > index 54e5317f00f1..63b4d0e6fc29 100644
> > --- a/fs/nfsd/nfs4state.c
> > +++ b/fs/nfsd/nfs4state.c
> > @@ -3580,7 +3580,7 @@ static struct nfsd4_conn *__nfsd4_find_conn(struct svc_xprt *xpt, struct nfsd4_s
> > }
> > 
> > static __be32 nfsd4_match_existing_connection(struct svc_rqst *rqst,
> > -				struct nfsd4_session *session, u32 req)
> > +		struct nfsd4_session *session, u32 req, struct nfsd4_conn **conn)
> > {
> > 	struct nfs4_client *clp = session->se_client;
> > 	struct svc_xprt *xpt = rqst->rq_xprt;
> > @@ -3603,6 +3603,8 @@ static __be32 nfsd4_match_existing_connection(struct svc_rqst *rqst,
> > 	else
> > 		status = nfserr_inval;
> > 	spin_unlock(&clp->cl_lock);
> > +	if (status == nfs_ok && conn)
> > +		*conn = c;
> > 	return status;
> > }
> > 
> > @@ -3627,8 +3629,16 @@ __be32 nfsd4_bind_conn_to_session(struct svc_rqst *rqstp,
> > 	status = nfserr_wrong_cred;
> > 	if (!nfsd4_mach_creds_match(session->se_client, rqstp))
> > 		goto out;
> > -	status = nfsd4_match_existing_connection(rqstp, session, bcts->dir);
> > -	if (status == nfs_ok || status == nfserr_inval)
> > +	status = nfsd4_match_existing_connection(rqstp, session,
> > +			bcts->dir, &conn);
> > +	if (status == nfs_ok) {
> > +		if (bcts->dir == NFS4_CDFC4_FORE_OR_BOTH ||
> > +				bcts->dir == NFS4_CDFC4_BACK)
> > +			conn->cn_flags |= NFS4_CDFC4_BACK;
> > +		nfsd4_probe_callback(session->se_client);
> > +		goto out;
> > +	}
> > +	if (status == nfserr_inval)
> > 		goto out;
> > 	status = nfsd4_map_bcts_dir(&bcts->dir);
> > 	if (status)
> > -- 
> > 2.9.5
> > 
> 
> --
> Chuck Lever
> 
>