I'm sorry to necro this post, but the response here is why the Linux community gets such a bad rap. When a direct question is asked, someone who knows the answer, won't answer the question, and will instead tell you you're doing it wrong, or your question is wrong.
For anyone hoping to find an answer to the question:
[rootshare]
path = /mnt/user
comment =
browseable = no
valid users = user1 user2