linux-kernel - [PATCH 3.16 227/305] Fix reconnect to not defer smb3 session reconnect long after socket reconnect

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Message-ID: <lsq.1471110171.102528195@decadent.org.uk>
Date:	Sat, 13 Aug 2016 18:42:51 +0100
From:	Ben Hutchings <ben@...adent.org.uk>
To:	linux-kernel@...r.kernel.org, stable@...r.kernel.org
CC:	akpm@...ux-foundation.org, "Steve French" <smfrench@...il.com>,
	"Steve French" <steve.french@...marydata.com>,
	"Pavel Shilovsky" <pshilovsky@...ba.org>
Subject: [PATCH 3.16 227/305] Fix reconnect to not defer smb3 session
 reconnect long after socket reconnect

3.16.37-rc1 review patch.  If anyone has any objections, please let me know.

------------------

From: Steve French <smfrench@...il.com>

commit 4fcd1813e6404dd4420c7d12fb483f9320f0bf93 upstream.

Azure server blocks clients that open a socket and don't do anything on it.
In our reconnect scenarios, we can reconnect the tcp session and
detect the socket is available but we defer the negprot and SMB3 session
setup and tree connect reconnection until the next i/o is requested, but
this looks suspicous to some servers who expect SMB3 negprog and session
setup soon after a socket is created.

In the echo thread, reconnect SMB3 sessions and tree connections
that are disconnected.  A later patch will replay persistent (and
resilient) handle opens.

Signed-off-by: Steve French <steve.french@...marydata.com>
Acked-by: Pavel Shilovsky <pshilovsky@...ba.org>
Signed-off-by: Ben Hutchings <ben@...adent.org.uk>
---
 fs/cifs/connect.c |  4 +++-
 fs/cifs/smb2pdu.c | 27 +++++++++++++++++++++++++++
 2 files changed, 30 insertions(+), 1 deletion(-)

--- a/fs/cifs/connect.c
+++ b/fs/cifs/connect.c
@@ -410,7 +410,9 @@ cifs_echo_request(struct work_struct *wo
 	 * server->ops->need_neg() == true. Also, no need to ping if
 	 * we got a response recently.
 	 */
-	if (!server->ops->need_neg || server->ops->need_neg(server) ||
+
+	if (server->tcpStatus == CifsNeedReconnect ||
+	    server->tcpStatus == CifsExiting || server->tcpStatus == CifsNew ||
 	    (server->ops->can_echo && !server->ops->can_echo(server)) ||
 	    time_before(jiffies, server->lstrp + SMB_ECHO_INTERVAL - HZ))
 		goto requeue_echo;
--- a/fs/cifs/smb2pdu.c
+++ b/fs/cifs/smb2pdu.c
@@ -1590,6 +1590,33 @@ SMB2_echo(struct TCP_Server_Info *server
 
 	cifs_dbg(FYI, "In echo request\n");
 
+	if (server->tcpStatus == CifsNeedNegotiate) {
+		struct list_head *tmp, *tmp2;
+		struct cifs_ses *ses;
+		struct cifs_tcon *tcon;
+
+		cifs_dbg(FYI, "Need negotiate, reconnecting tcons\n");
+		spin_lock(&cifs_tcp_ses_lock);
+		list_for_each(tmp, &server->smb_ses_list) {
+			ses = list_entry(tmp, struct cifs_ses, smb_ses_list);
+			list_for_each(tmp2, &ses->tcon_list) {
+				tcon = list_entry(tmp2, struct cifs_tcon,
+						  tcon_list);
+				/* add check for persistent handle reconnect */
+				if (tcon && tcon->need_reconnect) {
+					spin_unlock(&cifs_tcp_ses_lock);
+					rc = smb2_reconnect(SMB2_ECHO, tcon);
+					spin_lock(&cifs_tcp_ses_lock);
+				}
+			}
+		}
+		spin_unlock(&cifs_tcp_ses_lock);
+	}
+
+	/* if no session, renegotiate failed above */
+	if (server->tcpStatus == CifsNeedNegotiate)
+		return -EIO;
+
 	rc = small_smb2_init(SMB2_ECHO, NULL, (void **)&req);
 	if (rc)
 		return rc;