SMB3: Log at least once if tree connect fails during reconnect

Adding an extra debug message to show if a tree connect failure during
reconnect (and made it a log once so it doesn't spam the logs).
Saw a case recently where tree connect repeatedly returned
access denied on reconnect and it wasn't as easy to spot as it
should have been.

Signed-off-by: Steve French <[e-mail]>
Reviewed-by: Aurelien Aptel <[e-mail]>

fs/cifs/cifssmb.c

···
 	mutex_unlock(&ses->session_mutex);
 	cifs_dbg(FYI, "reconnect tcon rc = %d\n", rc);
 
-	if (rc)
+	if (rc) {
+		printk_once(KERN_WARNING "reconnect tcon failed rc = %d\n", rc);
 		goto out;
+	}
 
 	atomic_inc(&tconInfoReconnectCount);
 

fs/cifs/smb2pdu.c

···
 	mutex_unlock(&tcon->ses->session_mutex);
 
 	cifs_dbg(FYI, "reconnect tcon rc = %d\n", rc);
-	if (rc)
+	if (rc) {
+		/* If sess reconnected but tcon didn't, something strange ... */
+		printk_once(KERN_WARNING "reconnect tcon failed rc = %d\n", rc);
 		goto out;
+	}
 
 	if (smb2_command != SMB2_INTERNAL_CMD)
 		queue_delayed_work(cifsiod_wq, &server->reconnect, 0);