From: Chuck Lever chuck.lever@oracle.com
commit 6221f1d9b63fed6260273e59a2b89ab30537a811 upstream.
Currently, after the forward channel connection goes away, backchannel operations are causing soft lockups on the server because call_transmit_status's SOFTCONN logic ignores ENOTCONN. Such backchannel Calls are aggressively retried until the client reconnects.
Backchannel Calls should use RPC_TASK_NOCONNECT rather than RPC_TASK_SOFTCONN. If there is no forward connection, the server is not capable of establishing a connection back to the client, thus that backchannel request should fail before the server attempts to send it. Commit 58255a4e3ce5 ("NFSD: NFSv4 callback client should use RPC_TASK_SOFTCONN") was merged several years before RPC_TASK_NOCONNECT was available.
Because setup_callback_client() explicitly sets NOPING, the NFSv4.0 callback connection depends on the first callback RPC to initiate a connection to the client. Thus NFSv4.0 needs to continue to use RPC_TASK_SOFTCONN.
Suggested-by: Trond Myklebust trondmy@hammerspace.com Signed-off-by: Chuck Lever chuck.lever@oracle.com Cc: stable@vger.kernel.org # v4.20+ Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- fs/nfsd/nfs4callback.c | 4 +++- net/sunrpc/svc_xprt.c | 2 ++ net/sunrpc/xprtrdma/svc_rdma_backchannel.c | 2 ++ net/sunrpc/xprtsock.c | 1 + 4 files changed, 8 insertions(+), 1 deletion(-)
--- a/fs/nfsd/nfs4callback.c +++ b/fs/nfsd/nfs4callback.c @@ -1241,6 +1241,7 @@ nfsd4_run_cb_work(struct work_struct *wo container_of(work, struct nfsd4_callback, cb_work); struct nfs4_client *clp = cb->cb_clp; struct rpc_clnt *clnt; + int flags;
if (cb->cb_need_restart) { cb->cb_need_restart = false; @@ -1269,7 +1270,8 @@ nfsd4_run_cb_work(struct work_struct *wo }
cb->cb_msg.rpc_cred = clp->cl_cb_cred; - rpc_call_async(clnt, &cb->cb_msg, RPC_TASK_SOFT | RPC_TASK_SOFTCONN, + flags = clp->cl_minorversion ? RPC_TASK_NOCONNECT : RPC_TASK_SOFTCONN; + rpc_call_async(clnt, &cb->cb_msg, RPC_TASK_SOFT | flags, cb->cb_ops ? &nfsd4_cb_ops : &nfsd4_cb_probe_ops, cb); }
--- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -1028,6 +1028,8 @@ static void svc_delete_xprt(struct svc_x
dprintk("svc: svc_delete_xprt(%p)\n", xprt); xprt->xpt_ops->xpo_detach(xprt); + if (xprt->xpt_bc_xprt) + xprt->xpt_bc_xprt->ops->close(xprt->xpt_bc_xprt);
spin_lock_bh(&serv->sv_lock); list_del_init(&xprt->xpt_list); --- a/net/sunrpc/xprtrdma/svc_rdma_backchannel.c +++ b/net/sunrpc/xprtrdma/svc_rdma_backchannel.c @@ -242,6 +242,8 @@ static void xprt_rdma_bc_close(struct rpc_xprt *xprt) { dprintk("svcrdma: %s: xprt %p\n", __func__, xprt); + + xprt_disconnect_done(xprt); xprt->cwnd = RPC_CWNDSHIFT; }
--- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -2714,6 +2714,7 @@ static int bc_send_request(struct rpc_rq
static void bc_close(struct rpc_xprt *xprt) { + xprt_disconnect_done(xprt); }
/*