[cinder-csi-plugin] multi-attach shared file-system

[iRazoR]

Hi,
I´m trying to understand how cinder-csi-plugin handles multi-attach volumes with focus on the filesystem because I couldn´t find any hint in the documentation.

I need a RWX Volume for an high available application with concurrent write access.
I´m able to create a multi-attach PV but by default it´s formatted as ext4 which is not suitable for multiple instances as far as I know.
Is there any magic behind cinder-csi which handles concurrent access with ext4 or what´s the recommendation here?
I saw that I can set the prefered fstype in the storageclass but is there any clustered filesystem that is supported by the nodeplugin?