nfsvers=4.2 falls back to Linux kernel driver

[nikolaiderzhak]

With helm chart v4.9.0 and EKS 1.30 (AMI: bottlerocket-aws-k8s-1.30-x86_64-v1.22.0-b6684b72) we have issue using nfsvers=4.2 in both dynamic and static provisioning methods described in: https://github.com/kubernetes-csi/csi-driver-nfs/tree/master/deploy/example

With nfsvers=4.1 it mounts volume fine.

We suspect it fails back to Linux kernel driver when version is 4.2 and use CSI driver with 4.1 version.

As it also mounts volume if we use AMI with nfs in lsmod/kernel available.

I would like to ask you to add information about this behaviour/mechanism to the mentioned above documentation.
Also probably you can provide link to the code where it happens.

We are ok with NFS v4.1, but v4.2 was giving us performance bump, so I wonder if there are plans to implement support for v4.2.

Thank you in advance, folks

[andyzhangx]

@nikolaiderzhak
the example nfs storage class is just example, do you want to add some notes into this file? feel free to raise a PR, thanks.

csi-driver-nfs/deploy/example/storageclass-nfs.yaml

Lines 15 to 16 in 5aa0a04

	mountOptions:
	- nfsvers=4.1

[nikolaiderzhak]

@andyzhangx I can do that, but first I would like to confirm that my assumption is correct. Let us wait a bit. If no details on it appears I will just comment that version 4.2 will use Linux driver, not CSI one.