Raw block volume snapshot failure

[madhurnawandar]

Raw block volume snapshot fails with error like:

 Warning  SnapshotCreationFailed  6s    csi-snapshotter csi-hostpath  Failed to create snapshot: failed to take snapshot of the volume, pvc-cb8d96b6-5d40-11e9-bcc0-0236f32917fe: "rpc error: code = Internal desc = failed create snapshot: exit status 1: tar: can't change directory to '/csi-data-dire6fc6eb8-5d40-11e9-97b2-0236f32917fe': Not a directory\n"

There are 2 reasons to this:
1 : Following constants are defined incorrect:

provisionRoot      = "/csi-data-dir"
snapshotRoot       = "/csi-data-dir"

Thjey should be

provisionRoot      = "/csi-data-dir/"
snapshotRoot       = "/csi-data-dir/"

2: In case of raw block volumes the volume content comes as a single file as against a directory in case of a filesystem volume. So the tar command with -C option won't work. Instead, a tar file should be created directly from the file corresponding to the raw block volume. Something like

tar czf <tar_fikle_name> <file_for_raw_block_volume>