Return-Path: linux-nfs-owner@vger.kernel.org Received: from userp1040.oracle.com ([156.151.31.81]:22377 "EHLO userp1040.oracle.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751511AbaJTSJr convert rfc822-to-8bit (ORCPT ); Mon, 20 Oct 2014 14:09:47 -0400 Content-Type: text/plain; charset=windows-1252 Mime-Version: 1.0 (Mac OS X Mail 7.3 \(1878.6\)) Subject: Re: [PATCH v1 13/16] NFS: Add sidecar RPC client support From: Chuck Lever In-Reply-To: <54454762.8020506@Netapp.com> Date: Mon, 20 Oct 2014 14:09:42 -0400 Cc: Linux NFS Mailing List Message-Id: References: <20141016192919.13414.3151.stgit@manet.1015granger.net> <20141016194000.13414.83844.stgit@manet.1015granger.net> <54454762.8020506@Netapp.com> To: Anna Schumaker Sender: linux-nfs-owner@vger.kernel.org List-ID: On Oct 20, 2014, at 1:33 PM, Anna Schumaker wrote: > On 10/16/14 15:40, Chuck Lever wrote: >> So far, TCP is the only transport that supports bi-directional RPC. >> >> When mounting with NFSv4.1 using a transport that does not support >> bi-directional RPC, establish a TCP sidecar connection to handle >> backchannel traffic for a session. The sidecar transport does not >> use its forward channel except for sending BIND_CONN_TO_SESSION >> operations. >> >> This commit adds logic to create and destroy the sidecar transport. >> Subsequent commits add logic to use the transport. > > I thought NFS v4.0 also uses a separate connection for the backchannel? For NFSv4.0, the server opens a connection to the client. For NFSv4.1, the client opens the side car connection to the server, and then performs BIND_CONN_TO_SESSION, an operation not in NFSv4.0. The processes are not terribly similar. > Can any of that code be reused here, rather than creating new sidecar structures? Since it?s the client opening a connection in this case, I don?t see any obvious common code paths that I haven?t already re-used. I?m open to suggestions. > Anna > >> >> Signed-off-by: Chuck Lever >> --- >> fs/nfs/client.c | 1 + >> fs/nfs/nfs4client.c | 54 +++++++++++++++++++++++++++++++++++++++++++++ >> include/linux/nfs_fs_sb.h | 2 ++ >> 3 files changed, 57 insertions(+) >> >> diff --git a/fs/nfs/client.c b/fs/nfs/client.c >> index 6a4f366..19f49bf 100644 >> --- a/fs/nfs/client.c >> +++ b/fs/nfs/client.c >> @@ -78,6 +78,7 @@ const struct rpc_program nfs_program = { >> .stats = &nfs_rpcstat, >> .pipe_dir_name = NFS_PIPE_DIRNAME, >> }; >> +EXPORT_SYMBOL_GPL(nfs_program); >> >> struct rpc_stat nfs_rpcstat = { >> .program = &nfs_program >> diff --git a/fs/nfs/nfs4client.c b/fs/nfs/nfs4client.c >> index 5f4b818..b1cc35e 100644 >> --- a/fs/nfs/nfs4client.c >> +++ b/fs/nfs/nfs4client.c >> @@ -213,6 +213,8 @@ static void nfs4_destroy_callback(struct nfs_client *clp) >> { >> if (__test_and_clear_bit(NFS_CS_CALLBACK, &clp->cl_res_state)) >> nfs_callback_down(clp->cl_mvops->minor_version, clp->cl_net); >> + if (clp->cl_bc_rpcclient) >> + rpc_shutdown_client(clp->cl_bc_rpcclient); >> } >> >> static void nfs4_shutdown_client(struct nfs_client *clp) >> @@ -291,6 +293,53 @@ int nfs40_init_client(struct nfs_client *clp) >> >> #if defined(CONFIG_NFS_V4_1) >> >> +/* >> + * Create a separate rpc_clnt using TCP that can provide a >> + * backchannel service. >> + */ >> +static int nfs41_create_sidecar_rpc_client(struct nfs_client *clp) >> +{ >> + struct sockaddr_storage address; >> + struct sockaddr *sap = (struct sockaddr *)&address; >> + struct rpc_create_args args = { >> + .net = clp->cl_net, >> + .protocol = XPRT_TRANSPORT_TCP, >> + .address = sap, >> + .addrsize = clp->cl_addrlen, >> + .servername = clp->cl_hostname, >> + .program = &nfs_program, >> + .version = clp->rpc_ops->version, >> + .flags = (RPC_CLNT_CREATE_DISCRTRY | >> + RPC_CLNT_CREATE_NOPING), >> + }; >> + struct rpc_clnt *clnt; >> + struct rpc_cred *cred; >> + >> + if (rpc_xprt_is_bidirectional(clp->cl_rpcclient)) >> + return 0; >> + >> + if (test_bit(NFS_CS_NORESVPORT, &clp->cl_flags)) >> + args.flags |= RPC_CLNT_CREATE_NONPRIVPORT; >> + memcpy(sap, &clp->cl_addr, clp->cl_addrlen); >> + rpc_set_port(sap, NFS_PORT); >> + cred = nfs4_get_clid_cred(clp); >> + if (cred) { >> + args.authflavor = cred->cr_auth->au_flavor; >> + put_rpccred(cred); >> + } else >> + args.authflavor = RPC_AUTH_UNIX; >> + >> + clnt = rpc_create(&args); >> + if (IS_ERR(clnt)) { >> + dprintk("%s: cannot create side-car RPC client. Error = %ld\n", >> + __func__, PTR_ERR(clnt)); >> + return PTR_ERR(clnt); >> + } >> + >> + clp->cl_bc_rpcclient = clnt; >> + return 0; >> +} >> + >> /** >> * nfs41_init_client - nfs_client initialization tasks for NFSv4.1+ >> * @clp - nfs_client to initialize >> @@ -300,6 +349,11 @@ int nfs40_init_client(struct nfs_client *clp) >> int nfs41_init_client(struct nfs_client *clp) >> { >> struct nfs4_session *session = NULL; >> + int ret; >> + >> + ret = nfs41_create_sidecar_rpc_client(clp); >> + if (ret) >> + return ret; >> >> /* >> * Create the session and mark it expired. >> diff --git a/include/linux/nfs_fs_sb.h b/include/linux/nfs_fs_sb.h >> index 922be2e..159d703 100644 >> --- a/include/linux/nfs_fs_sb.h >> +++ b/include/linux/nfs_fs_sb.h >> @@ -87,6 +87,8 @@ struct nfs_client { >> >> /* The sequence id to use for the next CREATE_SESSION */ >> u32 cl_seqid; >> + /* The optional sidecar backchannel transport */ >> + struct rpc_clnt *cl_bc_rpcclient; >> /* The flags used for obtaining the clientid during EXCHANGE_ID */ >> u32 cl_exchange_flags; >> struct nfs4_session *cl_session; /* shared session */ >> >> -- >> To unsubscribe from this list: send the line "unsubscribe linux-nfs" in >> the body of a message to majordomo@vger.kernel.org >> More majordomo info at http://vger.kernel.org/majordomo-info.html > -- Chuck Lever