[jira] [Created] (MESOS-6360) The handling of whiteout files in provisioner is not correct

["Qian Zhang (JIRA)" <ji...@apache.org>]

Qian Zhang created MESOS-6360:
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             Summary: The handling of whiteout files in provisioner is not correct
                 Key: MESOS-6360
                 URL: https://issues.apache.org/jira/browse/MESOS-6360
             Project: Mesos
          Issue Type: Bug
            Reporter: Qian Zhang
            Assignee: Qian Zhang


Currently when user launches a container from a Docker image via universal containerizer, we always handle the whiteout files in {{ProvisionerProcess::__provision()}} after the Docker image is pulled by puller/fetcher and the rootfs for the container is provisioned by backend.

However this is actually not correct, because the way to handle whiteout files is backend dependent, that means for different backends, we need to handle whiteout files in different ways, e.g.:
* AUFS backend: It seems the AUFS whiteout ({{.wh.<filename/dirname>}} and {{.wh..wh..opq}}) is the whiteout standard in Docker (see [this comment | https://github.com/docker/docker/blob/v1.12.1/pkg/archive/archive.go#L259:L262] for details), so that means after the Docker image is pulled, the whiteout files in the store in it are already in aufs format, then we do not need to do anything about whiteout file handling because the aufs mount done in {{AufsBackendProcess::provision()}} will handle it automatically.
* Overlay backend: Overlayfs has its own whiteout files (see [this doc | https://www.kernel.org/doc/Documentation/filesystems/overlayfs.txt] for details), so we need to convert the aufs whiteout files to overlayfs whiteout files before we do the overlay mount in {{OverlayBackendProcess::provision}} which will automatically handle the overlayfs whiteout files.
* Copy backend: We need to manually handle the aufs whiteout files when we copy each layer in {{CopyBackendProcess::_provision()}}.



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