Add tools for mounting VHD as NBD from Linux

nbd-unmount

@@ -0,0 +1,36 @@
+#!/bin/bash
+# disconnects a VHD device from linux (should be unmounted)
+# nbd-unmount path-to-vhd
+DRIVE="$1"
+QEMU_NBD_COMMAND="ps aux|grep '[q]emu-nbd.*--connect='|tr -s ' '|cut -f 11- -d ' '"
+
+if [ -z "$DRIVE" ]; then
+	echo "Drive not provided"
+	exit 1
+fi
+
+if ! [ -f "$DRIVE" ]; then
+	echo "$DRIVE not existing"
+	exit 1
+fi
+
+# iterate over all mounted nbds
+NBD_TARGET=
+while read MOUNT; do
+	if echo "$MOUNT" | egrep "$DRIVE$" > /dev/null; then
+		NBD_TARGET="$(echo "$MOUNT" | sed -E 's!.*(--connect=?|-c\s+)([^[:space:]]+).*!\2!g')"
+	fi
+done < <(eval "$QEMU_NBD_COMMAND")
+
+if [ -z "$NBD_TARGET" ]; then
+	echo "$DRIVE not mounted"
+	exit 1
+fi
+
+echo going to unmount "$NBD_TARGET"
+if mount | grep ^"$NBD_TARGET" -q ; then
+	echo "$NBD_TARGET mounted, refusing to detach"
+	exit 1
+fi
+
+echo qemu-nbd --disconnect=$NBD_TARGET