You don't say if the seafile user data are of the client or the server.
If it's about the server data, I'd say the share would be useless
because the data is stored in blobs.
For sharing the client data, you might want to check if the
virtualization technology you use can do that for you. Though, the
standard way is to share the data as for any other baremetal system
whatever the virtualization is. For Windows/Unix, CIFS (samba) is the
main protocol.
I can see no reason not to share the data of seafile *from* the system
running the seafile client. I would be much cautious when it comes to
*put* seafile data *into* a shared location because of the
rights/filenames/resiliance limitations coming with the remote accessing
software (and not fit well with seafile expectations).
--
Nicolas Sebrecht