Hi, support for ACL/xattr in reiserfs is unfortunately broken since version 4.4 (getfacl/setfacl fails with EINVAL). The problem was solved by Al Viro on 2016-04-10 with this commit:
79a628d14ec7ee9adfdc3ce04343d5ff7ec20c18 reiserfs: switch to generic_{get,set,remove}xattr() The patch applies on 4.4.14 with some fuzziness but it solves the issue with no apparent side effects. I launched a small stress-test (some hours of random set/get ACL on a reiserfs partition) with no problem. Could you please backport the commit for v4.4 stable? Thanks Andrea Cascio Nucleus srl