NodeExpand may resize fs for block volume

[msau42]

Looking back at resizer.Resize implementation, it checks the format on the disk before attempting a resize. The problem is, the presence of a filesystem doesn't mean that the PVC is a Filesystem type. A user could mount the volume as Block and manage an ext4/xfs filesystem themselves.

I think fixing this may require adding VolumeCapabilities to the Controller/NodeExpandVolumeRequest

/kind bug
/assign @davidz627
cc @gnufied

[davidz627]

Just to confirm, the intended behavior is:
If the VolumeCapability is Block and the user manages a fs by themselves, we should NOT resize their fs
?

[msau42]

correct

[gnufied]

okay, I have file a bug against CSI for adding the capability - container-storage-interface/spec#380

[gnufied]

Actually I am wondering if we can solve majority of this problem, without making a change in CSI specs. See when volume is of type raw-block the volumePath that you will get with NodeExpandVolume will be a device-path not a mounted file system path. So we can use that information and not perform any file system level expansion when NodeExpandVolume is called on raw block devices.

I think it may still be worth adding capability to NodeExpandVolume and ControllerExpandVolume call but - it will fall under "nice" to have territory and a driver can use this optional information to skip a operation entirely.

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[davidz627]

/remove-lifecycle stale

[davidz627]

VolumeCapability was added (container-storage-interface/spec#381) so this should be easy to skip now

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