From 6221f1d9b63fed6260273e59a2b89ab30537a811 Mon Sep 17 00:00:00 2001 From: Chuck Lever Date: Fri, 17 Apr 2020 12:40:31 -0400 Subject: [PATCH] SUNRPC: Fix backchannel RPC soft lockups 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 Signed-off-by: Chuck Lever Cc: # v4.20+ --- 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(-) diff --git a/fs/nfsd/nfs4callback.c b/fs/nfsd/nfs4callback.c index c3b11a715082..5cf91322de0f 100644 --- a/fs/nfsd/nfs4callback.c +++ b/fs/nfsd/nfs4callback.c @@ -1312,6 +1312,7 @@ nfsd4_run_cb_work(struct work_struct *work) 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; @@ -1340,7 +1341,8 @@ nfsd4_run_cb_work(struct work_struct *work) } 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); } diff --git a/net/sunrpc/svc_xprt.c b/net/sunrpc/svc_xprt.c index e27e3532ec75..92f2c08c67a5 100644 --- a/net/sunrpc/svc_xprt.c +++ b/net/sunrpc/svc_xprt.c @@ -1040,6 +1040,8 @@ static void svc_delete_xprt(struct svc_xprt *xprt) 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); diff --git a/net/sunrpc/xprtrdma/svc_rdma_backchannel.c b/net/sunrpc/xprtrdma/svc_rdma_backchannel.c index d510a3a15d4b..af7eb8d202ae 100644 --- a/net/sunrpc/xprtrdma/svc_rdma_backchannel.c +++ b/net/sunrpc/xprtrdma/svc_rdma_backchannel.c @@ -244,6 +244,8 @@ 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; } diff --git a/net/sunrpc/xprtsock.c b/net/sunrpc/xprtsock.c index 0bda8a73e8a8..845d0be805ec 100644 --- a/net/sunrpc/xprtsock.c +++ b/net/sunrpc/xprtsock.c @@ -2584,6 +2584,7 @@ static int bc_send_request(struct rpc_rqst *req) static void bc_close(struct rpc_xprt *xprt) { + xprt_disconnect_done(xprt); } /*