cifs: Send witness register messages to userspace daemon in echo task

If the daemon starts after mounting a share, or if it crashes, this
provides a mechanism to register again.
Signed-off-by: Samuel Cabrero <scabrero@suse.de>
Reviewed-by: Aurelien Aptel <aaptel@suse.com>
Signed-off-by: Steve French <stfrench@microsoft.com>

fs/cifs/cifs_swn.c

@@ -540,3 +540,18 @@ void cifs_swn_dump(struct seq_file *m)
 	mutex_unlock(&cifs_swnreg_idr_mutex);
 	seq_puts(m, "\n");
 }
+
+void cifs_swn_check(void)
+{
+	struct cifs_swn_reg *swnreg;
+	int id;
+	int ret;
+
+	mutex_lock(&cifs_swnreg_idr_mutex);
+	idr_for_each_entry(&cifs_swnreg_idr, swnreg, id) {
+		ret = cifs_swn_send_register_message(swnreg);
+		if (ret < 0)
+			cifs_dbg(FYI, "%s: Failed to send register message: %d\n", __func__, ret);
+	}
+	mutex_unlock(&cifs_swnreg_idr_mutex);
+}

fs/cifs/cifs_swn.h

@@ -20,4 +20,6 @@ extern int cifs_swn_notify(struct sk_buff *skb, struct genl_info *info);
 
 extern void cifs_swn_dump(struct seq_file *m);
 
+extern void cifs_swn_check(void);
+
 #endif /* _CIFS_SWN_H */

fs/cifs/connect.c

@@ -405,6 +405,11 @@ cifs_echo_request(struct work_struct *work)
 		cifs_dbg(FYI, "Unable to send echo request to server: %s\n",
 			 server->hostname);
 
+#ifdef CONFIG_CIFS_SWN_UPCALL
+	/* Check witness registrations */
+	cifs_swn_check();
+#endif
+
 requeue_echo:
 	queue_delayed_work(cifsiod_wq, &server->echo, server->echo_interval);
 }