Custom master node action

I want to implement a backup action. This action will disable flushing
first and then copy files and finally enable flushing. To do this, I should
call ClusterUpdateSettingsRequest in my master node action. Can someone
explain how can I do this? Do I need to inject client and call this on
client? Or can I simply construct the request and pass it a a mechanism
which is already injected (for example clusterService, transportService,

Mustafa Sener