cifs: do not disable interface polling on failure

BugLink: https://bugs.launchpad.net/bugs/2118807

When a server has multichannel enabled, we keep polling the server
for interfaces periodically. However, when this query fails, we
disable the polling. This can be problematic as it takes away the
chance for the server to start advertizing again.

This change reschedules the delayed work, even if the current call
failed. That way, multichannel sessions can recover.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
Cc: stable@vger.kernel.org
Signed-off-by: Steve French <stfrench@microsoft.com>
(cherry picked from commit 42ca547b13a20e7cbb04fbdf8d5f089ac4bb35b7)
Signed-off-by: Vinicius Peixoto <vinicius.peixoto@canonical.com>
Acked-by: Manuel Diewald <manuel.diewald@canonical.com>
Acked-by: Alessio Faina <alessio.faina@canonical.com>
Signed-off-by: Vinicius Peixoto <vinicius.peixoto@canonical.com>

Author: sprasad-microsoft

fs/smb/client/connect.c

@@ -116,13 +116,9 @@ static void smb2_query_server_interfaces(struct work_struct *work)
 	rc = server->ops->query_server_interfaces(xid, tcon, false);
 	free_xid(xid);
 
-	if (rc) {
-		if (rc == -EOPNOTSUPP)
-			return;
-
+	if (rc)
 		cifs_dbg(FYI, "%s: failed to query server interfaces: %d\n",
 				__func__, rc);
-	}
 
 	queue_delayed_work(cifsiod_wq, &tcon->query_interfaces,
 			   (SMB_INTERFACE_POLL_INTERVAL * HZ));

fs/smb/client/smb2pdu.c

@@ -422,6 +422,10 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		free_xid(xid);
 		ses->flags &= ~CIFS_SES_FLAGS_PENDING_QUERY_INTERFACES;
 
+		/* regardless of rc value, setup polling */
+		queue_delayed_work(cifsiod_wq, &tcon->query_interfaces,
+				   (SMB_INTERFACE_POLL_INTERVAL * HZ));
+
 		mutex_unlock(&ses->session_mutex);
 
 		if (rc == -EOPNOTSUPP && ses->chan_count > 1) {
@@ -442,11 +446,8 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		if (ses->chan_max > ses->chan_count &&
 		    ses->iface_count &&
 		    !SERVER_IS_CHAN(server)) {
-			if (ses->chan_count == 1) {
+			if (ses->chan_count == 1)
 				cifs_server_dbg(VFS, "supports multichannel now\n");
-				queue_delayed_work(cifsiod_wq, &tcon->query_interfaces,
-						 (SMB_INTERFACE_POLL_INTERVAL * HZ));
-			}
 
 			cifs_try_adding_channels(ses);
 		}