use s3 tags/headers to record permissions on objects, so preserving them through distcp round trips

S3 now supports object tags, attributes which can be updated during the life of an object.

S3A could use that to preserve the permissions/ACLs of objects when copied from elsewhere, in particular from HDFS. This would ensure that data backed up from HDFS preserves all the permission information needed when doing a recovery from S3 to HDFS.

Azure WASB does exactly this already.