This is a note to let you know that I've just added the patch titled nfsd: back channel stuck in SEQ4_STATUS_CB_PATH_DOWN to the 5.14-stable tree which can be found at: http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary The filename of the patch is: nfsd-back-channel-stuck-in-seq4_status_cb_path_down.patch and it can be found in the queue-5.14 subdirectory. If you, or anyone else, feels it should not be added to the stable tree, please let <stable@xxxxxxxxxxxxxxx> know about it. commit 5b8d14945fbe1c2253721b9b5dbf4d36fa83f644 Author: Dai Ngo <dai.ngo@xxxxxxxxxx> Date: Thu Sep 16 14:22:12 2021 -0400 nfsd: back channel stuck in SEQ4_STATUS_CB_PATH_DOWN [ Upstream commit 02579b2ff8b0becfb51d85a975908ac4ab15fba8 ] 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@xxxxxxxxxx> Signed-off-by: Chuck Lever <chuck.lever@xxxxxxxxxx> Signed-off-by: Sasha Levin <sashal@xxxxxxxxxx> diff --git a/fs/nfsd/nfs4state.c b/fs/nfsd/nfs4state.c index 3d805f5b1f5d..1c33a5255893 100644 --- a/fs/nfsd/nfs4state.c +++ b/fs/nfsd/nfs4state.c @@ -3570,7 +3570,7 @@ 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; @@ -3593,6 +3593,8 @@ 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; } @@ -3617,8 +3619,16 @@ __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)