SMB2 ioct dfs_get_referral returns wrong error
Most clients don't care, but we return
where we should return
It turns out the MS Hyper-V cares which error we return.
Steps to Reproduce:
Connect from any windows client and capture network traffic on port 445.
Look at the capture with Wireshark, and see the SMB2 ioctl (typically
just after a tree connect for a disk share) and its error code.