sunrpc: Add xprt after nfs4_test_session_trunk()

Multipathing: In case of NFSv3, rpc_clnt_test_and_add_xprt() adds
the xprt to xprt switch (i.e. xps) if rpc_call_null_helper() returns
success. But in case of NFSv4.1, it needs to do EXCHANGEID to verify
the path along with check for session trunking.

Add the xprt in nfs4_test_session_trunk() only when
nfs4_detect_session_trunking() returns success. Also release refcount
hold by rpc_clnt_setup_test_and_add_xprt().
Signed-off-by: Santosh kumar pradhan <santoshkumar.pradhan@wdc.com>
Tested-by: Suresh Jayaraman <suresh.jayaraman@wdc.com>
Reported-by: Aditya Agnihotri <aditya.agnihotri@wdc.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/internal.h

@@ -568,9 +568,9 @@ extern int nfs40_walk_client_list(struct nfs_client *clp,
 extern int nfs41_walk_client_list(struct nfs_client *clp,
 				struct nfs_client **result,
 				const struct cred *cred);
-extern int nfs4_test_session_trunk(struct rpc_clnt *,
-				struct rpc_xprt *,
-				void *);
+extern void nfs4_test_session_trunk(struct rpc_clnt *clnt,
+				struct rpc_xprt *xprt,
+				void *data);
 
 static inline struct inode *nfs_igrab_and_active(struct inode *inode)
 {

fs/nfs/nfs4_fs.h

@@ -65,7 +65,8 @@ struct nfs4_minor_version_ops {
 			nfs4_stateid *, const struct cred *);
 	struct nfs_seqid *
 		(*alloc_seqid)(struct nfs_seqid_counter *, gfp_t);
-	int	(*session_trunk)(struct rpc_clnt *, struct rpc_xprt *, void *);
+	void	(*session_trunk)(struct rpc_clnt *clnt,
+			struct rpc_xprt *xprt, void *data);
 	const struct rpc_call_ops *call_sync_ops;
 	const struct nfs4_state_recovery_ops *reboot_recovery_ops;
 	const struct nfs4_state_recovery_ops *nograce_recovery_ops;

fs/nfs/nfs4proc.c

@@ -8082,7 +8082,7 @@ int nfs4_proc_exchange_id(struct nfs_client *clp, const struct cred *cred)
  * @xprt: the rpc_xprt to test
  * @data: call data for _nfs4_proc_exchange_id.
  */
-int nfs4_test_session_trunk(struct rpc_clnt *clnt, struct rpc_xprt *xprt,
+void nfs4_test_session_trunk(struct rpc_clnt *clnt, struct rpc_xprt *xprt,
 			    void *data)
 {
 	struct nfs4_add_xprt_data *adata = (struct nfs4_add_xprt_data *)data;
@@ -8099,15 +8099,17 @@ int nfs4_test_session_trunk(struct rpc_clnt *clnt, struct rpc_xprt *xprt,
 	/* Test connection for session trunking. Async exchange_id call */
 	task = nfs4_run_exchange_id(adata->clp, adata->cred, sp4_how, xprt);
 	if (IS_ERR(task))
-		return PTR_ERR(task);
+		return;
 
 	status = task->tk_status;
 	if (status == 0)
 		status = nfs4_detect_session_trunking(adata->clp,
 				task->tk_msg.rpc_resp, xprt);
 
+	if (status == 0)
+		rpc_clnt_xprt_switch_add_xprt(clnt, xprt);
+
 	rpc_put_task(task);
-	return status;
 }
 EXPORT_SYMBOL_GPL(nfs4_test_session_trunk);
 

include/linux/sunrpc/clnt.h

@@ -128,8 +128,8 @@ struct rpc_create_args {
 };
 
 struct rpc_add_xprt_test {
-	int (*add_xprt_test)(struct rpc_clnt *,
-		struct rpc_xprt *,
+	void (*add_xprt_test)(struct rpc_clnt *clnt,
+		struct rpc_xprt *xprt,
 		void *calldata);
 	void *data;
 };

net/sunrpc/clnt.c

@@ -2661,6 +2661,9 @@ int rpc_clnt_setup_test_and_add_xprt(struct rpc_clnt *clnt,
 	/* rpc_xprt_switch and rpc_xprt are deferrenced by add_xprt_test() */
 	xtest->add_xprt_test(clnt, xprt, xtest->data);
 
+	xprt_put(xprt);
+	xprt_switch_put(xps);
+
 	/* so that rpc_clnt_add_xprt does not call rpc_xprt_switch_add_xprt */
 	return 1;
 out_err: