Choose Y here if you want to allow SMB3 compliant clients
to access files residing on this system using SMB3 protocol.
To compile the SMB3 server support as a module,
choose M here: the module will be called ksmbd.

You may choose to use a samba server instead, in which
case you can choose N here.

You also need to install user space programs which can be found
in ksmbd-tools, available from
https://github.com/cifsd-team/ksmbd-tools.
More detail about how to run the ksmbd kernel server is
available via README file
(https://github.com/cifsd-team/ksmbd-tools/blob/master/README).

ksmbd kernel server includes support for auto-negotiation,
Secure negotiate, Pre-authentication integrity, oplock/lease,
compound requests, multi-credit, packet signing, RDMA(smbdirect),
smb3 encryption, copy-offload, secure per-user session
establishment via NTLM or NTLMv2.

source code:

fs/ksmbd/