Turned out I misinterpreted the spec...

Cc: Tom Haynes <thomas.haynes@primarydata.com>
Reported-by: NJean Spector <jean@primarydata.com>
Signed-off-by: NPeng Tao <tao.peng@primarydata.com>
Signed-off-by: NTrond Myklebust <trond.myklebust@primarydata.com>