On Oct 20, 2014, at 1:33 PM, Anna Schumaker <Anna.Schumaker@xxxxxxxxxx> 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 <chuck.lever@xxxxxxxxxx>
>> ---
>> 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 */
>>
>> --
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>
--
Chuck Lever
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