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.
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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