Keep the LVM-based dmeventd plugins from trying to manipulate the dmeventd

monitoring state of the logical volumes they are currently acting on.

Until now, every time a logical volume has been changed by a dmeventd plugin,
this plugin would have called back to dmeventd through the external FIFO
mechanism. I am fairly sure this was superfluous, inefficient and possibly even
dangerous.

daemons/dmeventd/plugins/lvm2/dmeventd_lvm.c

@@ -113,6 +113,7 @@ int dmeventd_lvm2_init(void)
 			_mem_pool = NULL;
 			goto out;
 		}
+		lvm2_disable_dmeventd_monitoring(_lvm_handle);
 		/* FIXME Temporary: move to dmeventd core */
 		lvm2_run(_lvm_handle, "_memlock_inc");
 	}

tools/lvm2cmd.h

@@ -51,6 +51,12 @@ void lvm2_log_fn(lvm2_log_fn_t log_fn);
  */ 
 void *lvm2_init(void);
 
+/*
+ * Disable any dmeventd calls that the library may otherwise do. Useful to avoid
+ * recursive calls from dmeventd to itself.
+ */
+void lvm2_disable_dmeventd_monitoring(void *handle);
+
 /*
  * Set log level (as above) if using built-in logging function. 
  * Default is LVM2_LOG_PRINT.  Use LVM2_LOG_SUPPRESS to suppress output.

tools/lvmcmdlib.c

@@ -97,6 +97,10 @@ int lvm2_run(void *handle, const char *cmdline)
 	return ret;
 }
 
+void lvm2_disable_dmeventd_monitoring(void *handle) {
+	init_dmeventd_monitor(DMEVENTD_MONITOR_IGNORE);
+}
+
 void lvm2_log_level(void *handle, int level)
 {
 	struct cmd_context *cmd = (struct cmd_context *) handle;