1 files changed, 118 insertions, 13 deletions

diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index c75a80bb6d9e..2eb29fa278c3 100644
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -163,6 +163,9 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 	int rc = 0;
 	struct nls_table *nls_codepage = NULL;
 	struct cifs_ses *ses;
+	int xid;
+	struct TCP_Server_Info *pserver;
+	unsigned int chan_index;
 
 	/*
 	 * SMB2s NegProt, SessSetup, Logoff do not have tcon yet so
@@ -223,6 +226,12 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 			return -EAGAIN;
 		}
 	}
+
+	/* if server is marked for termination, cifsd will cleanup */
+	if (server->terminate) {
+		spin_unlock(&server->srv_lock);
+		return -EHOSTDOWN;
+	}
 	spin_unlock(&server->srv_lock);
 
 again:
@@ -242,11 +251,23 @@ again:
 
 	mutex_lock(&ses->session_mutex);
 	/*
+	 * if this is called by delayed work, and the channel has been disabled
+	 * in parallel, the delayed work can continue to execute in parallel
+	 * there's a chance that this channel may not exist anymore
+	 */
+	spin_lock(&server->srv_lock);
+	if (server->tcpStatus == CifsExiting) {
+		spin_unlock(&server->srv_lock);
+		mutex_unlock(&ses->session_mutex);
+		rc = -EHOSTDOWN;
+		goto out;
+	}
+
+	/*
 	 * Recheck after acquire mutex. If another thread is negotiating
 	 * and the server never sends an answer the socket will be closed
 	 * and tcpStatus set to reconnect.
 	 */
-	spin_lock(&server->srv_lock);
 	if (server->tcpStatus == CifsNeedReconnect) {
 		spin_unlock(&server->srv_lock);
 		mutex_unlock(&ses->session_mutex);
@@ -283,6 +304,53 @@ again:
 
 	rc = cifs_negotiate_protocol(0, ses, server);
 	if (!rc) {
+		/*
+		 * if server stopped supporting multichannel
+		 * and the first channel reconnected, disable all the others.
+		 */
+		if (ses->chan_count > 1 &&
+		    !(server->capabilities & SMB2_GLOBAL_CAP_MULTI_CHANNEL)) {
+			if (SERVER_IS_CHAN(server)) {
+				cifs_dbg(VFS, "server %s does not support " \
+					 "multichannel anymore. skipping secondary channel\n",
+					 ses->server->hostname);
+
+				spin_lock(&ses->chan_lock);
+				chan_index = cifs_ses_get_chan_index(ses, server);
+				if (chan_index == CIFS_INVAL_CHAN_INDEX) {
+					spin_unlock(&ses->chan_lock);
+					goto skip_terminate;
+				}
+
+				ses->chans[chan_index].server = NULL;
+				spin_unlock(&ses->chan_lock);
+
+				/*
+				 * the above reference of server by channel
+				 * needs to be dropped without holding chan_lock
+				 * as cifs_put_tcp_session takes a higher lock
+				 * i.e. cifs_tcp_ses_lock
+				 */
+				cifs_put_tcp_session(server, 1);
+
+				server->terminate = true;
+				cifs_signal_cifsd_for_reconnect(server, false);
+
+				/* mark primary server as needing reconnect */
+				pserver = server->primary_server;
+				cifs_signal_cifsd_for_reconnect(pserver, false);
+
+skip_terminate:
+				mutex_unlock(&ses->session_mutex);
+				rc = -EHOSTDOWN;
+				goto out;
+			} else {
+				cifs_server_dbg(VFS, "does not support " \
+					 "multichannel anymore. disabling all other channels\n");
+				cifs_disable_secondary_channels(ses);
+			}
+		}
+
 		rc = cifs_setup_session(0, ses, server, nls_codepage);
 		if ((rc == -EACCES) && !tcon->retry) {
 			mutex_unlock(&ses->session_mutex);
@@ -307,17 +375,44 @@ skip_sess_setup:
 		tcon->need_reopen_files = true;
 
 	rc = cifs_tree_connect(0, tcon, nls_codepage);
-	mutex_unlock(&ses->session_mutex);
 
 	cifs_dbg(FYI, "reconnect tcon rc = %d\n", rc);
 	if (rc) {
 		/* If sess reconnected but tcon didn't, something strange ... */
+		mutex_unlock(&ses->session_mutex);
 		cifs_dbg(VFS, "reconnect tcon failed rc = %d\n", rc);
 		goto out;
 	}
 
+	if (!rc &&
+	    (server->capabilities & SMB2_GLOBAL_CAP_MULTI_CHANNEL)) {
+		mutex_unlock(&ses->session_mutex);
+
+		/*
+		 * query server network interfaces, in case they change
+		 */
+		xid = get_xid();
+		rc = SMB3_request_interfaces(xid, tcon, false);
+		free_xid(xid);
+
+		if (rc)
+			cifs_dbg(FYI, "%s: failed to query server interfaces: %d\n",
+				 __func__, rc);
+
+		if (ses->chan_max > ses->chan_count &&
+		    !SERVER_IS_CHAN(server)) {
+			if (ses->chan_count == 1)
+				cifs_server_dbg(VFS, "supports multichannel now\n");
+
+			cifs_try_adding_channels(ses);
+		}
+	} else {
+		mutex_unlock(&ses->session_mutex);
+	}
+
 	if (smb2_command != SMB2_INTERNAL_CMD)
-		mod_delayed_work(cifsiod_wq, &server->reconnect, 0);
+		if (mod_delayed_work(cifsiod_wq, &server->reconnect, 0))
+			cifs_put_tcp_session(server, false);
 
 	atomic_inc(&tconInfoReconnectCount);
 out:
@@ -3808,6 +3903,13 @@ void smb2_reconnect_server(struct work_struct *work)
 	/* Prevent simultaneous reconnects that can corrupt tcon->rlist list */
 	mutex_lock(&pserver->reconnect_mutex);
 
+	/* if the server is marked for termination, drop the ref count here */
+	if (server->terminate) {
+		cifs_put_tcp_session(server, true);
+		mutex_unlock(&pserver->reconnect_mutex);
+		return;
+	}
+
 	INIT_LIST_HEAD(&tmp_list);
 	INIT_LIST_HEAD(&tmp_ses_list);
 	cifs_dbg(FYI, "Reconnecting tcons and channels\n");
@@ -3852,12 +3954,6 @@ void smb2_reconnect_server(struct work_struct *work)
 		}
 		spin_unlock(&ses->chan_lock);
 	}
-	/*
-	 * Get the reference to server struct to be sure that the last call of
-	 * cifs_put_tcon() in the loop below won't release the server pointer.
-	 */
-	if (tcon_exist || ses_exist)
-		server->srv_count++;
 
 	spin_unlock(&cifs_tcp_ses_lock);
 
@@ -3905,13 +4001,17 @@ void smb2_reconnect_server(struct work_struct *work)
 
 done:
 	cifs_dbg(FYI, "Reconnecting tcons and channels finished\n");
-	if (resched)
+	if (resched) {
 		queue_delayed_work(cifsiod_wq, &server->reconnect, 2 * HZ);
+		mutex_unlock(&pserver->reconnect_mutex);
+
+		/* no need to put tcp session as we're retrying */
+		return;
+	}
 	mutex_unlock(&pserver->reconnect_mutex);
 
 	/* now we can safely release srv struct */
-	if (tcon_exist || ses_exist)
-		cifs_put_tcp_session(server, 1);
+	cifs_put_tcp_session(server, true);
 }
 
 int
@@ -3931,7 +4031,12 @@ SMB2_echo(struct TCP_Server_Info *server)
 	    server->ops->need_neg(server)) {
 		spin_unlock(&server->srv_lock);
 		/* No need to send echo on newly established connections */
-		mod_delayed_work(cifsiod_wq, &server->reconnect, 0);
+		spin_lock(&cifs_tcp_ses_lock);
+		server->srv_count++;
+		spin_unlock(&cifs_tcp_ses_lock);
+		if (mod_delayed_work(cifsiod_wq, &server->reconnect, 0))
+			cifs_put_tcp_session(server, false);
+
 		return rc;
 	}
 	spin_unlock(&server->srv_lock);