NFSv4.1 respect server's max size in CREATE_SESSION

BugLink: http://bugs.launchpad.net/bugs/1745052

[ Upstream commit 03385332 ]

Currently client doesn't respect max sizes server returns in CREATE_SESSION.
nfs4_session_set_rwsize() gets called and server->rsize, server->wsize are 0
so they never get set to the sizes returned by the server.
Signed-off-by: Olga Kornievskaia <kolga@netapp.com>
Signed-off-by: Anna Schumaker <Anna.Schumaker@Netapp.com>
Signed-off-by: Sasha Levin <alexander.levin@verizon.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Signed-off-by: Khalid Elmously <khalid.elmously@canonical.com>
Signed-off-by: Stefan Bader <stefan.bader@canonical.com>

fs/nfs/nfs4client.c

@@ -895,9 +895,9 @@ static void nfs4_session_set_rwsize(struct nfs_server *server)
 	server_resp_sz = sess->fc_attrs.max_resp_sz - nfs41_maxread_overhead;
 	server_rqst_sz = sess->fc_attrs.max_rqst_sz - nfs41_maxwrite_overhead;
 
-	if (server->rsize > server_resp_sz)
+	if (!server->rsize || server->rsize > server_resp_sz)
 		server->rsize = server_resp_sz;
-	if (server->wsize > server_rqst_sz)
+	if (!server->wsize || server->wsize > server_rqst_sz)
 		server->wsize = server_rqst_sz;
 #endif /* CONFIG_NFS_V4_1 */
 }