From 6b3830ba31f207cc83c32295c596f538d9418ea1 Mon Sep 17 00:00:00 2001
From: Rusty Bird <rustybird@net-c.com>
Date: Sat, 30 Dec 2017 21:27:28 +0000
Subject: [PATCH] udev-block-add-change: ignore unconnected Network Block
 Device

"modprobe nbd" shouldn't instantly send 16 zero byte nbd devices to
dom0.
---
 udev/udev-block-add-change | 6 ++++++
 1 file changed, 6 insertions(+)

diff --git a/udev/udev-block-add-change b/udev/udev-block-add-change
index 3f184af..9ee4b86 100755
--- a/udev/udev-block-add-change
+++ b/udev/udev-block-add-change
@@ -119,6 +119,12 @@ if [ "$MAJOR" -eq 7 -a ! -d /sys/$DEVPATH/loop ]; then
     exit 0
 fi
 
+# or unconnected Network Block Device
+if [ "$MAJOR" -eq 43 -a ! -e /sys/$DEVPATH/pid ]; then
+    xs_remove
+    exit 0
+fi
+
 # ... and loop devices from excluded directories
 if [[ "$NAME" = 'loop'* ]]; then
     backing_file=$(cat /sys/block/${NAME}/loop/backing_file)