Description
The zfs filesystem has NFS4 ACLs built right into it. The use of those ACLs work on other OSs, however, its use has never been ported to Linux. A while ago, issue #170 was created for POSIX and NFS4 acl support. It was closed after POSIX support as added, however NFS4 was not implemented.
NFS4 implementation was held up because the tools to manage NFS4 acls were not available. Now, some distros are using the "nfs4-acl-tools" package for NFS4 acl management now. It uses nfs4_getfacl, nfs4_setfacl, and nfs4_editfacl.
In followup discussions in issue #170, @behlendorf stated:
I haven't looked in to nfs4 acls for a few years but it looks like they're making really good progress with the user space components. Based on a cursory reading of the nfs4-acl-tools source it looks like the expected user/kernel interface is via an xattr named system.nfs4_acl which contains the raw xdr encoded acl.
Getting this working might only require adding xattr handlers for a system.nfs4_acl xattr which translates between the nfs4 acl stored internally by ZFS and the representation of it expected by the utilities. Since NFSv4 is the only consumer of this the kernel doesn't provide any generic functionality we can use we'd need to write the functions to do this encoding/decoding.
On the surface getting this working looks very possible. I think it would be great if a developer wanted to tackle this feature.
So, I created an new issue, separate from the closed original #170 issue to track the progress of NFS4.