smb3: track the instance of each session for debugging

Each time we reconnect to the same server, bump an instance
counter (and display in /proc/fs/cifs/DebugData) to make it
easier to debug.
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Reviewed-by: Pavel Shilovsky <pshilov@microsoft.com>

fs/cifs/cifs_debug.c

@@ -285,7 +285,7 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 			if ((ses->serverDomain == NULL) ||
 				(ses->serverOS == NULL) ||
 				(ses->serverNOS == NULL)) {
-				seq_printf(m, "\n%d) Name: %s Uses: %d Capability: 0x%x\tSession Status: %d\t",
+				seq_printf(m, "\n%d) Name: %s Uses: %d Capability: 0x%x\tSession Status: %d ",
 					i, ses->serverName, ses->ses_count,
 					ses->capabilities, ses->status);
 				if (ses->session_flags & SMB2_SESSION_FLAG_IS_GUEST)
@@ -296,16 +296,18 @@ static int cifs_debug_data_proc_show(struct seq_file *m, void *v)
 				seq_printf(m,
 				    "\n%d) Name: %s  Domain: %s Uses: %d OS:"
 				    " %s\n\tNOS: %s\tCapability: 0x%x\n\tSMB"
-				    " session status: %d\t",
+				    " session status: %d ",
 				i, ses->serverName, ses->serverDomain,
 				ses->ses_count, ses->serverOS, ses->serverNOS,
 				ses->capabilities, ses->status);
 			}
 			if (server->rdma)
 				seq_printf(m, "RDMA\n\t");
-			seq_printf(m, "TCP status: %d\n\tLocal Users To "
+			seq_printf(m, "TCP status: %d Instance: %d\n\tLocal Users To "
 				   "Server: %d SecMode: 0x%x Req On Wire: %d",
-				   server->tcpStatus, server->srv_count,
+				   server->tcpStatus,
+				   server->reconnect_instance,
+				   server->srv_count,
 				   server->sec_mode, in_flight(server));
 
 #ifdef CONFIG_CIFS_STATS2

fs/cifs/cifsglob.h

@@ -654,6 +654,7 @@ struct TCP_Server_Info {
 	/* 16th byte of RFC1001 workstation name is always null */
 	char workstation_RFC1001_name[RFC1001_NAME_LEN_WITH_NULL];
 	__u32 sequence_number; /* for signing, protected by srv_mutex */
+	__u32 reconnect_instance; /* incremented on each reconnect */
 	struct session_key session_key;
 	unsigned long lstrp; /* when we got last response from this server */
 	struct cifs_secmech secmech; /* crypto sec mech functs, descriptors */

fs/cifs/connect.c

@@ -2396,6 +2396,7 @@ cifs_get_tcp_session(struct smb_vol *volume_info)
 		volume_info->target_rfc1001_name, RFC1001_NAME_LEN_WITH_NULL);
 	tcp_ses->session_estab = false;
 	tcp_ses->sequence_number = 0;
+	tcp_ses->reconnect_instance = 0;
 	tcp_ses->lstrp = jiffies;
 	spin_lock_init(&tcp_ses->req_lock);
 	INIT_LIST_HEAD(&tcp_ses->tcp_ses_list);

fs/cifs/smb2ops.c

@@ -110,6 +110,8 @@ smb2_set_credits(struct TCP_Server_Info *server, const int val)
 {
 	spin_lock(&server->req_lock);
 	server->credits = val;
+	if (val == 1)
+		server->reconnect_instance++;
 	spin_unlock(&server->req_lock);
 }