Add attach commands for losetup

bin/losetup-unmount

@@ -0,0 +1,30 @@
+#!/bin/bash
+# disconnects a VHD device from linux (should be unmounted)
+# nbd-unmount path-to-vhd
+DRIVE="$1"
+
+if [ -z "$DRIVE" ]; then
+	echo "Drive not provided"
+	exit 1
+fi
+
+if ! [ -f "$DRIVE" ]; then
+	echo "$DRIVE not existing"
+	exit 1
+fi
+
+EXISTING_DRIVE="$(losetup -l | tail -n +2 | tr -s ' ' | cut -f 6 | grep -w "$DRIVE")"
+if [ -z "$EXISTING_DRIVE" ]; then
+	echo "$DRIVE not mounted"
+	exit 1
+fi
+
+EXISTING_LOOP="$(losetup -l | tail -n +2 | tr -s ' ' | grep -w "$DRIVE" | cut -f 1 -d ' ')"
+LOOP_DEST="$(readlink -f $EXISTING_LOOP)"
+
+if mount | grep ^"$LOOP_DEST" -q ; then
+	echo "$LOOP_DEST mounted, refusing to detach"
+	exit 1
+fi
+
+losetup -d "$LOOP_DEST"