From bc9e4d1fe554ebd7df7aa033b1fb1fdfccc7adaf Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Marek=20Marczykowski-G=C3=B3recki?=
 <marmarek@invisiblethingslab.com>
Date: Sun, 22 Feb 2015 14:44:09 +0100
Subject: [PATCH] linux/block-snapshot: improve support for HVM domain

Handle stubdomains (the same device will be removed twice).
Use target domain name instead of stubdomain name for committing
template changes.
---
 linux/system-config/block-snapshot | 17 +++++++++++------
 1 file changed, 11 insertions(+), 6 deletions(-)

diff --git a/linux/system-config/block-snapshot b/linux/system-config/block-snapshot
index fb41856e..7822a07e 100755
--- a/linux/system-config/block-snapshot
+++ b/linux/system-config/block-snapshot
@@ -135,11 +135,10 @@ case "$command" in
           write_dev /dev/mapper/$dm_devname
         fi
         # Save domain name for template commit on device remove
-        domain=$(xenstore_read_default "$XENBUS_PATH/domain" '')
-        if [ -z "$domain" ]; then
-          domid=$(xenstore_read "$XENBUS_PATH/frontend-id")
-          domain=$(xl domname $domid)
-        fi
+        domid=$(xenstore_read "$XENBUS_PATH/frontend-id")
+        # Store name of target domain in case of stubdom
+        domid=$(xenstore_read_default "/local/domain/$domid/target" "$domid")
+        domain=$(xl domname $domid)
         echo $domain > "$HOTPLUG_STORE-domain"
 
         release_lock "block"
@@ -212,7 +211,13 @@ case "$command" in
 
         claim_lock "block"
 
-        use_count=$(dmsetup info $node|grep Open|awk '{print $3}')
+        use_count=$(dmsetup info $node 2>/dev/null|grep Open|awk '{print $3}')
+
+        if [ -z "$use_count" ]; then
+            log info "Device $node already removed"
+            release_lock "block"
+            exit 0
+        fi
 
         # do not remove snapshot if snapshot origin is still present
         if [ "${node/snapshot/}" != "$node" -a -e "/dev/mapper/origin-$(echo $node|cut -d- -f2)" ]; then