Set previous session id correctly on SMB3 reconnect

commit c2afb814 upstream.
Signed-off-by: Steve French <steve.french@primarydata.com>
Reported-by: David Goebel <davidgoe@microsoft.com>
[bwh: Backported to 3.16: adjust context]
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>

fs/cifs/smb2pdu.c

@@ -566,6 +566,7 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
 	char *security_blob;
 	unsigned char *ntlmssp_blob = NULL;
 	bool use_spnego = false; /* else use raw ntlmssp */
+	u64 previous_session = ses->Suid;
 
 	cifs_dbg(FYI, "Session Setup\n");
 
@@ -602,6 +603,10 @@ SMB2_sess_setup(const unsigned int xid, struct cifs_ses *ses,
 		return rc;
 
 	req->hdr.SessionId = 0; /* First session, not a reauthenticate */
+
+	/* if reconnect, we need to send previous sess id, otherwise it is 0 */
+	req->PreviousSessionId = previous_session;
+
 	req->VcNumber = 0; /* MBZ */
 	/* to enable echos and oplocks */
 	req->hdr.CreditRequest = cpu_to_le16(3);

fs/cifs/smb2pdu.h

@@ -245,7 +245,7 @@ struct smb2_sess_setup_req {
 	__le32 Channel;
 	__le16 SecurityBufferOffset;
 	__le16 SecurityBufferLength;
-	__le64 PreviousSessionId;
+	__u64 PreviousSessionId;
 	__u8   Buffer[1];	/* variable length GSS security buffer */
 } __packed;