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

[dai.ngo@oracle.com]

On 9/16/21 12:55 PM, Bruce Fields wrote:
> 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?

I don't, but I can create a pynfs test for reproduce the problem.

-Dai

>
> --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
>>
>>