How are NFSv4 ACLs working on Linux?

TrueNAS General
,
1

I’m a little confused by NFSv4 ACL support in TrueNAS CE. According to this PR, OpenZFS does not yet have NFSv4 ACLs working in Linux: https://github.com/openzfs/zfs/pull/16967

Also, the web docs say this with regard to the NFSv4 acltype: “default on FreeBSD, indicates that NFSv4-style ZFS ACLs should be used. These ACLs can be managed with the getfacl(1) and setfacl(1). The nfsv4 ZFS ACL type is not yet supported on Linux.”

If you run man zfsprops on a TrueNAS installation, you don’t see the “not yet supported on Linux” line. However, using nfs4_getfacl still results in an error: “Operation to request attribute not supported.”

Anyone know what’s going on with these ACLs? Is TrueNAS doing something special on top of OpenZFS here?

2

Using getfattr, I can see that my files have the xattr system.nfs4_acl_xdr. How does TrueNAS have this available when the OpenZFS PR hasn’t been merged yet? Also, are getfattr and setfattr calls shimmed to this somehow?

3

Oh, I failed to un-collapse the PR thread. Looks like TrueNAS has some Linux kernel changes to make this work? I hope this won’t cause a messy migration when OpenZFS merges the “definitive” version.

4

TrueNAS has both Linux and OpenZFS patches that they apply in order to make NFSv4 ACL work on Linux (among other things). See GitHub - truenas/linux: Linux kernel for TrueNAS SCALE or GitHub - truenas/zfs: OpenZFS on Linux and FreeBSD respectively.

If you want to operate on the NFSv4 ACL the commands are prefixed with nfs4xdr_. For example nfs4xdr_getacl or nfs4xdr_setfacl.

1 Like