[CRIU] [PATCH v2 12/12] p.haul: implement vz migration with shared ploops

[Alexander Burluka]

Final commit that introduces vz migration with ploops
that are located on shared disks.
Brief algorithm description:
After freezing container source side creates copy of
every shared ploop DiskDescriptor.xml (named DiskDescriptor.xml.copy)
and makes snapshots delta on origin and copy.
Origin snapshot would be used on destination after successful
"vzctl restore" operation (this snapshot delta is created
on source and merged on destination so it is create as "offline
snapshot")
On restore fail case DiskDescriptor.xml.copy would replace origin file
and merged with copy snapshot delta.

Signed-off-by: Alexander Burluka <aburluka at virtuozzo.com>
---
 phaul/iters.py | 32 ++++++++++++++++++++++----------
 1 file changed, 22 insertions(+), 10 deletions(-)

diff --git a/phaul/iters.py b/phaul/iters.py
index cbac565..453360e 100644
--- a/phaul/iters.py
+++ b/phaul/iters.py
@@ -202,27 +202,36 @@ class phaul_iter_worker:
 		self.htype.final_dump(root_pid, self.img, self.criu_connection, self.fs)
 		self.target_host.end_iter()
 
-		# Handle final FS and images sync on frozen htype
-		logging.info("Final FS and images sync")
-		fsstats = self.fs.stop_migration()
-		self.img.sync_imgs_to_target(self.target_host, self.htype,
-			self.connection.mem_sk)
+		try:
+			# Handle final FS and images sync on frozen htype
+			logging.info("Final FS and images sync")
+			fsstats = self.fs.stop_migration()
+
+			self.img.sync_imgs_to_target(self.target_host, self.htype,
+				self.connection.mem_sk)
 
-		# Restore htype on target
-		logging.info("Asking target host to restore")
-		self.target_host.restore_from_images()
-		logging.info("Restored on target host")
+			# Restore htype on target
+			logging.info("Asking target host to restore")
+			self.target_host.restore_from_images()
+			logging.info("Restored on target host")
+		except:
+			self.fs.restore_shared_backups()
+			raise
 
 		# Ack previous dump request to terminate all frozen tasks
 		resp = self.criu_connection.ack_notify()
 		if not resp.success:
-			raise Exception("Dump screwed up")
+			logging.warning("Bad notification from target host")
+
+		# cleanup shared disks backup
+		self.fs.cleanup_shared_backups()
 
 		dstats = criu_api.criu_get_dstats(self.img)
 		migration_stats.handle_iteration(dstats, fsstats)
 
 		logging.info("Migration succeeded")
 		self.htype.umount()
+		self.target_host.final_cleanup(self.fs.prepare_src_data({}))
 		migration_stats.handle_stop(self)
 		self.img.close()
 		self.criu_connection.close()
@@ -276,11 +285,14 @@ class phaul_iter_worker:
 			logging.info("Started on target host")
 
 		except:
+			self.fs.restore_shared_backups()
 			self.htype.start()
 			raise
 
 		logging.info("Migration succeeded")
+		self.fs.cleanup_shared_backups()
 		self.htype.umount()
+		self.target_host.final_cleanup(self.fs.prepare_src_data({}))
 		migration_stats.handle_stop()
 
 	def __check_live_iter_progress(self, index, dstats, prev_dstats):
-- 
1.8.3.1