cifs: Send a logoff request before removing a smb session

Send a smb session logoff request before removing smb session off of the list.
On a signed smb session, remvoing a session off of the list before sending
a logoff request results in server returning an error for lack of
smb signature.

Never seen an error during smb logoff, so as per MS-SMB2 3.2.5.1,
not sure how an error during logoff should be retried. So for now,
if a server returns an error to a logoff request, log the error and
remove the session off of the list.

Signed-off-by: Shirish Pargaonkar <shirishpargaonkar@gmail.com>
Reviewed-by: Jeff Layton <jlayton@redhat.com>
Signed-off-by: Steve French <smfrench@gmail.com>
diff --git a/fs/cifs/transport.c b/fs/cifs/transport.c
index 0ee6d24..b375709 100644
--- a/fs/cifs/transport.c
+++ b/fs/cifs/transport.c
@@ -431,13 +431,20 @@
 		return -EAGAIN;
 	}
 
-	if (ses->status != CifsGood) {
-		/* check if SMB session is bad because we are setting it up */
+	if (ses->status == CifsNew) {
 		if ((in_buf->Command != SMB_COM_SESSION_SETUP_ANDX) &&
 			(in_buf->Command != SMB_COM_NEGOTIATE))
 			return -EAGAIN;
 		/* else ok - we are setting up session */
 	}
+
+	if (ses->status == CifsExiting) {
+		/* check if SMB session is bad because we are setting it up */
+		if (in_buf->Command != SMB_COM_LOGOFF_ANDX)
+			return -EAGAIN;
+		/* else ok - we are shutting down session */
+	}
+
 	*ppmidQ = AllocMidQEntry(in_buf, ses->server);
 	if (*ppmidQ == NULL)
 		return -ENOMEM;