[CRIU] [PATCH 03/12] p.haul: Implement class shared_ploop

[Nikita Spiridonov]

Acked-by: Nikita Spiridonov <nspiridonov at virtuozzo.com>

On Fri, 2016-04-01 at 18:45 +0300, Alexander Burluka wrote:
> This class is required to do migration on ploops located
> on pstorage or other shared filesystems. That migration
> is performed via two snapshot scheme.
> 
> Signed-off-by: Alexander Burluka <aburluka at virtuozzo.com>
> ---
>  phaul/fs_haul_ploop.py | 27 +++++++++++++++++++++++++++
>  1 file changed, 27 insertions(+)
> 
> diff --git a/phaul/fs_haul_ploop.py b/phaul/fs_haul_ploop.py
> index b436d19..61c7465 100644
> --- a/phaul/fs_haul_ploop.py
> +++ b/phaul/fs_haul_ploop.py
> @@ -3,6 +3,7 @@
>  #
>  
>  import os
> +import shutil
>  import logging
>  import threading
>  import libploop
> @@ -31,6 +32,32 @@ def get_ploop_delta_abspath(delta_path, ct_priv):
>  		return os.path.join(ct_priv, delta_path)
>  
> 
> +def merge_ploop_snapshot(ddxml, guid):
> +	libploop.snapshot(ddxml).delete(guid)
> +
> +
> +class shared_ploop:
> +	def __init__(self, path):
> +		self.backup_ddxml = get_ddxml_path(path) + ".copy"
> +		self.orig_ddxml = get_ddxml_path(path)
> +

Minor - it is better to make backup_ddxml and orig_ddxml private
(self.__backup_ddxml and self.__orig_ddxml); up to you fix or not.

> +	def prepare(self):
> +		shutil.copyfile(self.orig_ddxml, self.backup_ddxml)
> +		self.orig_guid = libploop.snapshot(self.orig_ddxml).create_offline()
> +		self.backup_guid = libploop.snapshot(self.backup_ddxml).create()
> +
> +	def restore(self):
> +		if self.backup_guid:
> +			os.rename(self.backup_ddxml, self.orig_ddxml)
> +			merge_ploop_snapshot(self.orig_ddxml, self.backup_guid)
> +
> +	def cleanup(self):
> +		if self.orig_guid:
> +			# TODO add delta removing when igor add it to libploop
> +			os.remove(self.backup_ddxml)
> +			os.remove(self.backup_ddxml + ".lck")
> +
> +
>  class p_haul_fs:
>  	def __init__(self, deltas, ct_priv):
>  		"""Initialize ploop disks hauler