nfs: reject version and minorversion changes on remount attempts

Reported-by: Eric Doutreleau <edoutreleau@genoscope.cns.fr>
Signed-off-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>

fs/nfs/super.c

@@ -2143,6 +2143,8 @@ nfs_compare_remount_data(struct nfs_server *nfss,
 	if (data->flags != nfss->flags ||
 	    data->rsize != nfss->rsize ||
 	    data->wsize != nfss->wsize ||
+	    data->version != nfss->nfs_client->rpc_ops->version ||
+	    data->minorversion != nfss->nfs_client->cl_minorversion ||
 	    data->retrans != nfss->client->cl_timeout->to_retries ||
 	    data->auth_flavors[0] != nfss->client->cl_auth->au_flavor ||
 	    data->acregmin != nfss->acregmin / HZ ||
@@ -2197,6 +2199,8 @@ nfs_remount(struct super_block *sb, int *flags, char *raw_data)
 	data->timeo = 10U * nfss->client->cl_timeout->to_initval / HZ;
 	data->nfs_server.port = nfss->port;
 	data->nfs_server.addrlen = nfss->nfs_client->cl_addrlen;
+	data->version = nfsvers;
+	data->minorversion = nfss->nfs_client->cl_minorversion;
 	memcpy(&data->nfs_server.address, &nfss->nfs_client->cl_addr,
 		data->nfs_server.addrlen);