cifs: fix the cifs_reconnect path for DFS

BugLink: https://bugs.launchpad.net/bugs/2036450

Recently, the cifs_reconnect code was refactored into
two branches for regular vs dfs codepath. Some of my
recent changes were missing in the dfs path, namely the
code to enable periodic DNS query, and a missing lock.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Signed-off-by: Steve French <stfrench@microsoft.com>
(cherry picked from commit e154cb7)
Signed-off-by: Tim Gardner <tim.gardner@canonical.com>

Author: sprasad-microsoft

fs/cifs/connect.c

@@ -338,8 +338,10 @@ static int __cifs_reconnect(struct TCP_Server_Info *server,
 		}
 	} while (server->tcpStatus == CifsNeedReconnect);
 
+	spin_lock(&cifs_tcp_ses_lock);
 	if (server->tcpStatus == CifsNeedNegotiate)
 		mod_delayed_work(cifsiod_wq, &server->echo, 0);
+	spin_unlock(&cifs_tcp_ses_lock);
 
 	wake_up(&server->response_q);
 	return rc;
@@ -454,6 +456,7 @@ reconnect_dfs_server(struct TCP_Server_Info *server,
 		spin_unlock(&cifs_tcp_ses_lock);
 		cifs_swn_reset_server_dstaddr(server);
 		mutex_unlock(&server->srv_mutex);
+		mod_delayed_work(cifsiod_wq, &server->reconnect, 0);
 	} while (server->tcpStatus == CifsNeedReconnect);
 
 	if (target_hint)