ZFS silently discarding invalid acltype

This surprised me last week, so I’m passing it on for what it’s worth. I used my standard FreeBSD Ansible playbook to define a new zpool on a Linux host, and in the process inadvertently set the acltype to nfsv4, which Linux doesn’t support. At least, I thought? I checked the pool: # uname ==> Linux # zfs get acltype ==> acltype nfsv4 But according to the docs, emphasis added: Setting a type the platform does not support does not produce an error. On Linux, acltype=nfsv4 is handled identically to off — but zfs get acltype still reports nfsv4. A dataset can therefore look as though it has ACLs enabled while silently having none. I’m not a fan of silent failures in system software, but that’s a separate issue. Not having this defined correctly can cause problems on NFS, among other places. Thus, you’ll want to create your pools with the following on Linux. POSIX ACLs are stored as extended attributes: -O acltype=posix \ -O xattr=sa Again, the OpenZFS documentation is your friend here.…