ksmbd: return STATUS_NOT_SUPPORTED on unsupported smb2.0 dialect

ksmbd returned "Input/output error" when mounting with vers=2.0 to
ksmbd. It should return STATUS_NOT_SUPPORTED on unsupported smb2.0
dialect.

Cc: stable@vger.kernel.org
Reported-by: Steve French <stfrench@microsoft.com>
Signed-off-by: Namjae Jeon <linkinjeon@kernel.org>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/ksmbd/smb_common.c

@@ -434,7 +434,7 @@ int ksmbd_extract_shortname(struct ksmbd_conn *conn, const char *longname,
 
 static int __smb2_negotiate(struct ksmbd_conn *conn)
 {
-	return (conn->dialect >= SMB21_PROT_ID &&
+	return (conn->dialect >= SMB20_PROT_ID &&
 		conn->dialect <= SMB311_PROT_ID);
 }
 
@@ -465,7 +465,7 @@ int ksmbd_smb_negotiate_common(struct ksmbd_work *work, unsigned int command)
 		}
 	}
 
-	if (command == SMB2_NEGOTIATE_HE && __smb2_negotiate(conn)) {
+	if (command == SMB2_NEGOTIATE_HE) {
 		ret = smb2_handle_negotiate(work);
 		init_smb2_neg_rsp(work);
 		return ret;