No ZFS version has support for that. It has been discussed and it might be implemented at some point.
That said, I would like to point out that ZFS' dataset level operations are more powerful than reflinks. ZFS' dataset level operations give separate independent snapshot and clone capabilities. They also provide the ability to rollback without killing things on top (which is useful in some cases). You cannot do that with reflinks. I suppose the immutable bit could be used to fix a reflink so that it retains the state at creation, but that is racy. In the case of virtual machines which seems to be a major application of reflinks, zvols are lower overhead and support incremental send/recv.
One benefit of reflinks would be that regular users can use it, but regular users should be able to snapshot, clone and rollback when delegation support is implemented.
That said, I would like to point out that ZFS' dataset level operations are more powerful than reflinks. ZFS' dataset level operations give separate independent snapshot and clone capabilities. They also provide the ability to rollback without killing things on top (which is useful in some cases). You cannot do that with reflinks. I suppose the immutable bit could be used to fix a reflink so that it retains the state at creation, but that is racy. In the case of virtual machines which seems to be a major application of reflinks, zvols are lower overhead and support incremental send/recv.
One benefit of reflinks would be that regular users can use it, but regular users should be able to snapshot, clone and rollback when delegation support is implemented.