Create a PersistentVolume on LKE with a different fstype

We're deploying all/most of our backend services to LKE, coming from a hand-rolled (non containerized) environment. One of the needed components is MongoDB. For maximum performance MongoDB runs best on a XFS filesystem (see https://dzone.com/articles/xfs-vs-ext4-comparing-mongodb-performance-on-aws-e) and puts out a startup warning when running of a different (ext4) filesystem.

I'm installing MongoDB using this helm chart https://github.com/helm/charts/tree/master/stable/mongodb-replicaset

The chart allows to set a custom StorageClass, so I created the following StorageClass:

apiVersion: storage.k8s.io/v1
kind: StorageClass
metadata:
  name: linode-block-storage-retain-xfs
  annotations:
    lke.linode.com/caplke-version: v1.17.9-001
parameters:
    fstype: xfs
provisioner: linodebs.csi.linode.com
reclaimPolicy: Retain
volumeBindingMode: Immediate

The fstype: xfs part was cargo-culted from some other source.

When the StatefulSet tries to create the Pods it runs into a problem:

MountVolume.MountDevice failed for volume "pvc-c8da784c3d6a4e5a" : rpc error: code = Internal desc = Failed to format and mount device from ("/dev/disk/by-id/scsi-0Linode_Volume_pvcc8da784c3d6a4e5a") to ("/var/lib/kubelet/plugins/kubernetes.io/csi/pv/pvc-c8da784c3d6a4e5a/globalmount") with fstype ("xfs") and options ([]): executable file not found in $PATH

It seems the CSI driver (?) is trying to format the Volume (not sure who's responsible for formatting the Volume, I'm not really into the hard core Kubernetes/CSI internals (yet:)), but fails at finding the right tool (mkfs.xfs probably?)…

Is there a nice way to get support for XFS PeristentVolumes? Am I just CargoCulting the fstype part of the StorageClass incorrectly. Or would this be something that can/will be included into a subsequent Linode-CSI release?

There are some csi-linode- Pods running on the cluster. Would (manually) installing mkfs.xfs on these (nodes or master?) or on the Nodes itself be a possible workaround?