[CIFS] Do not send tree disconnect if session is already disconnected

Noticed this when tree connect timed out (due to Samba server crash) -
we try to send a tree disconnect for a tid that does not exist
since we don't have a valid tree id yet. This checks that the
session is valid before sending the tree disconnect to handle
this case.

Signed-off-by: Steve French <sfrench@us.ibm.com>
diff --git a/fs/cifs/CHANGES b/fs/cifs/CHANGES
index b486898..3a9b7a5 100644
--- a/fs/cifs/CHANGES
+++ b/fs/cifs/CHANGES
@@ -5,7 +5,7 @@
 on by default if server supports it).  Add forceuid and forcegid
 mount options (so that when negotiating unix extensions specifying
 which uid mounted does not immediately force the server's reported
-uids to be overridden).
+uids to be overridden).  Add support for scope moutn parm.
 
 Version 1.58
 ------------
diff --git a/fs/cifs/cifssmb.c b/fs/cifs/cifssmb.c
index b84c61d..58d65a9 100644
--- a/fs/cifs/cifssmb.c
+++ b/fs/cifs/cifssmb.c
@@ -729,7 +729,7 @@
 	 * the tcon is no longer on the list, so no need to take lock before
 	 * checking this.
 	 */
-	if (tcon->need_reconnect)
+	if ((tcon->need_reconnect) || (tcon->ses->need_reconnect))
 		return 0;
 
 	rc = small_smb_init(SMB_COM_TREE_DISCONNECT, 0, tcon,