smb3: add reconnect tracepoints

Add tracepoints for reconnecting an smb3 session

Example output (from trace-cmd) with the patch
(showing the session marked for reconnect, the stat failing, and then
the subsequent SMB3 commands after the server comes back up).
The "smb3_reconnect" event is the new one.

           cifsd-25993 [000] .... 29635.368265: smb3_reconnect: server=localhost current_mid=0x1e
            stat-26200 [001] .... 29638.516403: smb3_enter: 	cifs_revalidate_dentry_attr: xid=22
            stat-26200 [001] .... 29648.723296: smb3_exit_err: 	cifs_revalidate_dentry_attr: xid=22 rc=-112
     kworker/0:1-22830 [000] .... 29653.850947: smb3_cmd_done: 	sid=0x0 tid=0x0 cmd=0 mid=0
     kworker/0:1-22830 [000] .... 29653.851191: smb3_cmd_err: 	sid=0x8ae4683c tid=0x0 cmd=1 mid=1 status=0xc0000016 rc=-5
     kworker/0:1-22830 [000] .... 29653.855254: smb3_cmd_done: 	sid=0x8ae4683c tid=0x0 cmd=1 mid=2
     kworker/0:1-22830 [000] .... 29653.855482: smb3_cmd_done: 	sid=0x8ae4683c tid=0x8084f30d cmd=3 mid=3
Signed-off-by: Steve French <stfrench@microsoft.com>
Reviewed-by: Ronnie Sahlberg <lsahlber@redhat.com>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>

fs/cifs/connect.c

@@ -348,6 +348,7 @@ cifs_reconnect(struct TCP_Server_Info *server)
 	server->max_read = 0;
 
 	cifs_dbg(FYI, "Reconnecting tcp session\n");
+	trace_smb3_reconnect(server->CurrentMid, server->hostname);
 
 	/* before reconnecting the tcp session, mark the smb session (uid)
 		and the tid bad so they are not used until reconnected */

fs/cifs/trace.h

@@ -423,6 +423,32 @@ DEFINE_EVENT(smb3_open_done_class, smb3_##name,  \
 DEFINE_SMB3_OPEN_DONE_EVENT(open_done);
 DEFINE_SMB3_OPEN_DONE_EVENT(posix_mkdir_done);
 
+DECLARE_EVENT_CLASS(smb3_reconnect_class,
+	TP_PROTO(__u64	currmid,
+		char *hostname),
+	TP_ARGS(currmid, hostname),
+	TP_STRUCT__entry(
+		__field(__u64, currmid)
+		__field(char *, hostname)
+	),
+	TP_fast_assign(
+		__entry->currmid = currmid;
+		__entry->hostname = hostname;
+	),
+	TP_printk("server=%s current_mid=0x%llx",
+		__entry->hostname,
+		__entry->currmid)
+)
+
+#define DEFINE_SMB3_RECONNECT_EVENT(name)        \
+DEFINE_EVENT(smb3_reconnect_class, smb3_##name,  \
+	TP_PROTO(__u64	currmid,		\
+		char *hostname),		\
+	TP_ARGS(currmid, hostname))
+
+DEFINE_SMB3_RECONNECT_EVENT(reconnect);
+DEFINE_SMB3_RECONNECT_EVENT(partial_send_reconnect);
+
 #endif /* _CIFS_TRACE_H */
 
 #undef TRACE_INCLUDE_PATH

fs/cifs/transport.c

@@ -361,6 +361,8 @@ __smb_send_rqst(struct TCP_Server_Info *server, int num_rqst,
 		 * socket so the server throws away the partial SMB
 		 */
 		server->tcpStatus = CifsNeedReconnect;
+		trace_smb3_partial_send_reconnect(server->CurrentMid,
+						  server->hostname);
 	}
 smbd_done:
 	if (rc < 0 && rc != -EINTR)