[PATCH 11/14] cifs: handle when server starts supporting multichannel

[nspmangalore@gmail.com]

From: Shyam Prasad N <sprasad@microsoft.com>

When the user mounts with multichannel option, but the
server does not support it, there can be a time in future
where it can be supported.

With this change, such a case is handled.

Signed-off-by: Shyam Prasad N <sprasad@microsoft.com>
---
 fs/smb/client/cifsproto.h |  4 ++++
 fs/smb/client/connect.c   |  6 +++++-
 fs/smb/client/smb2pdu.c   | 31 ++++++++++++++++++++++++++++---
 3 files changed, 37 insertions(+), 4 deletions(-)

diff --git a/fs/smb/client/cifsproto.h b/fs/smb/client/cifsproto.h
index 65c84b3d1a65..5a4c1f1e0d91 100644
--- a/fs/smb/client/cifsproto.h
+++ b/fs/smb/client/cifsproto.h
@@ -132,6 +132,10 @@ extern int SendReceiveBlockingLock(const unsigned int xid,
 			struct smb_hdr *in_buf,
 			struct smb_hdr *out_buf,
 			int *bytes_returned);
+
+void
+smb2_query_server_interfaces(struct work_struct *work);
+
 void
 cifs_signal_cifsd_for_reconnect(struct TCP_Server_Info *server,
 				      bool all_channels);
diff --git a/fs/smb/client/connect.c b/fs/smb/client/connect.c
index e71aa33bf026..149cde77500e 100644
--- a/fs/smb/client/connect.c
+++ b/fs/smb/client/connect.c
@@ -116,7 +116,8 @@ static int reconn_set_ipaddr_from_hostname(struct TCP_Server_Info *server)
 	return rc;
 }
 
-static void smb2_query_server_interfaces(struct work_struct *work)
+void
+smb2_query_server_interfaces(struct work_struct *work)
 {
 	int rc;
 	int xid;
@@ -134,6 +135,9 @@ static void smb2_query_server_interfaces(struct work_struct *work)
 	if (rc) {
 		cifs_dbg(FYI, "%s: failed to query server interfaces: %d\n",
 				__func__, rc);
+
+		if (rc == -EOPNOTSUPP)
+			return;
 	}
 
 	queue_delayed_work(cifsiod_wq, &tcon->query_interfaces,
diff --git a/fs/smb/client/smb2pdu.c b/fs/smb/client/smb2pdu.c
index b7665155f4e2..2617437a4627 100644
--- a/fs/smb/client/smb2pdu.c
+++ b/fs/smb/client/smb2pdu.c
@@ -163,6 +163,7 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 	int rc = 0;
 	struct nls_table *nls_codepage = NULL;
 	struct cifs_ses *ses;
+	int xid;
 
 	/*
 	 * SMB2s NegProt, SessSetup, Logoff do not have tcon yet so
@@ -307,17 +308,41 @@ smb2_reconnect(__le16 smb2_command, struct cifs_tcon *tcon,
 		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 (smb2_command != SMB2_INTERNAL_CMD)
-		mod_delayed_work(cifsiod_wq, &server->reconnect, 0);
+	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_dbg(VFS, "server %s supports multichannel now\n",
+					 ses->server->hostname);
+
+			cifs_try_adding_channels(tcon->cifs_sb, ses);
+		}
+	} else {
+		mutex_unlock(&ses->session_mutex);
+	}
 
 	atomic_inc(&tconInfoReconnectCount);
 out:
-- 
2.34.1