NFSv4.1: use EXCHGID4_FLAG_USE_PNFS_DS for DS server

After receiving the location(s) of the DS server(s) in the
GETDEVINCEINFO, create the request for the clientid to such
server and indicate that the client is connecting to a DS.
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>

fs/nfs/nfs4client.c

@@ -232,6 +232,8 @@ struct nfs_client *nfs4_alloc_client(const struct nfs_client_initdata *cl_init)
 	__set_bit(NFS_CS_DISCRTRY, &clp->cl_flags);
 	__set_bit(NFS_CS_NO_RETRANS_TIMEOUT, &clp->cl_flags);
 
+	if (test_bit(NFS_CS_DS, &cl_init->init_flags))
+		__set_bit(NFS_CS_DS, &clp->cl_flags);
 	/*
 	 * Set up the connection to the server before we add add to the
 	 * global list.
@@ -1007,6 +1009,7 @@ struct nfs_client *nfs4_set_ds_client(struct nfs_server *mds_srv,
 	if (mds_srv->flags & NFS_MOUNT_NORESVPORT)
 		__set_bit(NFS_CS_NORESVPORT, &cl_init.init_flags);
 
+	__set_bit(NFS_CS_DS, &cl_init.init_flags);
 	/*
 	 * Set an authflavor equual to the MDS value. Use the MDS nfs_client
 	 * cl_ipaddr so as to use the same EXCHANGE_ID co_ownerid as the MDS

fs/nfs/nfs4proc.c

@@ -8787,6 +8787,8 @@ nfs4_run_exchange_id(struct nfs_client *clp, const struct cred *cred,
 #ifdef CONFIG_NFS_V4_1_MIGRATION
 	calldata->args.flags |= EXCHGID4_FLAG_SUPP_MOVED_MIGR;
 #endif
+	if (test_bit(NFS_CS_DS, &clp->cl_flags))
+		calldata->args.flags |= EXCHGID4_FLAG_USE_PNFS_DS;
 	msg.rpc_argp = &calldata->args;
 	msg.rpc_resp = &calldata->res;
 	task_setup_data.callback_data = calldata;
@@ -8864,6 +8866,8 @@ static int _nfs4_proc_exchange_id(struct nfs_client *clp, const struct cred *cre
 	/* Save the EXCHANGE_ID verifier session trunk tests */
 	memcpy(clp->cl_confirm.data, argp->verifier.data,
 	       sizeof(clp->cl_confirm.data));
+	if (resp->flags & EXCHGID4_FLAG_USE_PNFS_DS)
+		set_bit(NFS_CS_DS, &clp->cl_flags);
 out:
 	trace_nfs4_exchange_id(clp, status);
 	rpc_put_task(task);