[Bug] - FICLONE ioctl throws "operation not supported" on the latest release

[techxpert99]

Describe the bug

Our production EKS cluster deploys a daemonset whose working depends on this operation. It used to work until a few weeks ago, and now it doesn't. We use Karpenter to provision our instances and don't usually explicitly control the AMI. I suppose that this feature was disabled in the latest release since it used to work until the previous one. I filed this bug awslabs/amazon-eks-ami#2594 and got redirected to the Amazon Linux team, thus I'm opening a new one here.

To Reproduce

Provision an EC2 instance with the latest AL2023 AMI and execute (in bash shell) :

mkdir -p /var/tmp && cd /var/tmp && echo hello > original.txt && cp --reflink=always original.txt copy.txt

Above should throw "operation not supported"

Expected behavior

I expected the original behaviour to remain, even more so since it has not been mentioned in the release notes, unless I missed reading it.

Environment:

AWS Region: ap-south-1
Instance Type(s): c6a.4xlarge
Cluster Kubernetes version: 1.32
Node Kubernetes version: 1.32
AMI Version: amazon/amazon-eks-node-al2023-x86_64-standard-1.32-v20260114

Can we expect the behaviour to be restored in a later patch? If not, are we expected to create a custom AMI just to enable this operation? IMO this was a great feature since it allowed us to mount copy on write references into our containers, leading to significant space/ latency savings.