From 51d7c98d4952da94a3f639dd1371d63b348408dc Mon Sep 17 00:00:00 2001
From: Marchenko Alexandr <marchenko.alexandr@gmail.com>
Date: Tue, 1 Mar 2016 17:23:38 +0200
Subject: [PATCH] hyperv differencing disk

---
 plugins/providers/hyperv/action/import.rb        | 8 +++++++-
 plugins/providers/hyperv/config.rb               | 7 +++++--
 plugins/providers/hyperv/scripts/clone_vhd.ps1   | 9 +++++++++
 website/source/docs/hyperv/configuration.html.md | 1 +
 4 files changed, 22 insertions(+), 3 deletions(-)
 create mode 100644 plugins/providers/hyperv/scripts/clone_vhd.ps1

diff --git a/plugins/providers/hyperv/action/import.rb b/plugins/providers/hyperv/action/import.rb
index 330440f21..fc3e5facc 100644
--- a/plugins/providers/hyperv/action/import.rb
+++ b/plugins/providers/hyperv/action/import.rb
@@ -18,11 +18,13 @@ module VagrantPlugins
           maxmemory = env[:machine].provider_config.maxmemory
           cpus = env[:machine].provider_config.cpus
           vmname = env[:machine].provider_config.vmname
+          differencing_disk = env[:machine].provider_config.differencing_disk
 
           env[:ui].output("Configured Dynamic memory allocation, maxmemory is #{maxmemory}") if maxmemory
           env[:ui].output("Configured startup memory is #{memory}") if memory
           env[:ui].output("Configured cpus number is #{cpus}") if cpus
           env[:ui].output("Configured vmname is #{vmname}") if vmname
+          env[:ui].output("Configured differencing disk instead of cloning") if differencing_disk
 
           if !vm_dir.directory? || !hd_dir.directory?
             raise Errors::BoxInvalid
@@ -95,7 +97,11 @@ module VagrantPlugins
           env[:ui].detail("Cloning virtual hard drive...")
           source_path = image_path.to_s
           dest_path   = env[:machine].data_dir.join("#{image_filename}#{image_ext}").to_s
-          FileUtils.cp(source_path, dest_path)
+          if differencing_disk
+            env[:machine].provider.driver.execute("clone_vhd.ps1", {Source: source_path, Destination: dest_path})
+          else
+            FileUtils.cp(source_path, dest_path)
+          end
           image_path = dest_path
 
           # We have to normalize the paths to be Windows paths since
diff --git a/plugins/providers/hyperv/config.rb b/plugins/providers/hyperv/config.rb
index 2bff9663d..37047756d 100644
--- a/plugins/providers/hyperv/config.rb
+++ b/plugins/providers/hyperv/config.rb
@@ -3,7 +3,7 @@ require "vagrant"
 module VagrantPlugins
   module HyperV
     class Config < Vagrant.plugin("2", :config)
-      
+
       attr_accessor :ip_address_timeout # Time to wait for an IP address when booting, in seconds @return [Integer]
       attr_accessor :memory #  Memory size in mb @return [Integer]
       attr_accessor :maxmemory # Maximal memory size in mb enables dynamical memory allocation @return [Integer]
@@ -11,6 +11,7 @@ module VagrantPlugins
       attr_accessor :vmname # Name that will be shoen in Hyperv Manager @return [String]
       attr_accessor :vlan_id # VLAN ID for network interface for the virtual machine. @return [Integer]
       attr_accessor :mac # MAC address for network interface for the virtual machine. @return [String]
+      attr_accessor :differencing_disk # Create differencing disk instead of cloning whole VHD [Boolean]
 
       def initialize
         @ip_address_timeout = UNSET_VALUE
@@ -20,6 +21,7 @@ module VagrantPlugins
         @vmname = UNSET_VALUE
         @vlan_id  = UNSET_VALUE
         @mac  = UNSET_VALUE
+        @differencing_disk = UNSET_VALUE
       end
 
       def finalize!
@@ -28,10 +30,11 @@ module VagrantPlugins
         end
         @memory = nil if @memory == UNSET_VALUE
         @maxmemory = nil if @maxmemory == UNSET_VALUE
-        @cpus = nil if @cpus == UNSET_VALUE 
+        @cpus = nil if @cpus == UNSET_VALUE
         @vmname = nil if @vmname == UNSET_VALUE
         @vlan_id = nil if @vlan_id == UNSET_VALUE
         @mac = nil if @mac == UNSET_VALUE
+        @differencing_disk = false if @differencing_disk == UNSET_VALUE
       end
 
       def validate(machine)
diff --git a/plugins/providers/hyperv/scripts/clone_vhd.ps1 b/plugins/providers/hyperv/scripts/clone_vhd.ps1
new file mode 100644
index 000000000..8da4e90f0
--- /dev/null
+++ b/plugins/providers/hyperv/scripts/clone_vhd.ps1
@@ -0,0 +1,9 @@
+Param(
+    [Parameter(Mandatory=$true)]
+    [string]$Source,
+
+    [Parameter(Mandatory=$true)]
+    [string]$Destination
+)
+
+New-VHD -Path $Destination -ParentPath $Source -ErrorAction Stop
diff --git a/website/source/docs/hyperv/configuration.html.md b/website/source/docs/hyperv/configuration.html.md
index 86c77c8eb..ad25a62c9 100644
--- a/website/source/docs/hyperv/configuration.html.md
+++ b/website/source/docs/hyperv/configuration.html.md
@@ -28,3 +28,4 @@ you may set. A complete reference is shown below:
   * `ip_address_timeout` (integer) - The time in seconds to wait for the
     virtual machine to report an IP address. This defaults to 120 seconds.
     This may have to be increased if your VM takes longer to boot.
+  * `differencing_disk` (boolean) - Switch to use differencing disk intead of cloning whole VHD.