From 304e33a2fe2d006cc1063c8060c6e22c9ade3d59 Mon Sep 17 00:00:00 2001
From: Alexander Larsson <alexl@redhat.com>
Date: Thu, 6 Feb 2014 22:26:09 +0100
Subject: [PATCH] devmapper: Fix UnmountDevice for non-existing device

Properly error out if passed an id that doesn't exist.

Docker-DCO-1.1-Signed-off-by: Alexander Larsson <alexl@redhat.com> (github: alexlarsson)
---
 graphdriver/devmapper/deviceset.go | 3 +++
 1 file changed, 3 insertions(+)

diff --git a/graphdriver/devmapper/deviceset.go b/graphdriver/devmapper/deviceset.go
index 3dedfd75b5..c1f2f558a0 100644
--- a/graphdriver/devmapper/deviceset.go
+++ b/graphdriver/devmapper/deviceset.go
@@ -847,6 +847,9 @@ func (devices *DeviceSet) UnmountDevice(hash string, mode UnmountMode) error {
 	defer devices.Unlock()
 
 	info := devices.Devices[hash]
+	if info == nil {
+		return fmt.Errorf("UnmountDevice: no such device %s\n", hash)
+	}
 
 	if mode == UnmountFloat {
 		if info.floating {