[CRIU] [RFC v2] p.haul: Generate cgroup external mount map dynamically

[Cyrill Gorcunov]

From: Pavel Vokhmyanin <pvokhmyanin at virtuozzo.com>

libvzctl generates map dynamically by iterating through the known
list and looking up actual mount points, however p.haul just uses
hardcoded map. Due to difference in algorithms they might generate
different maps which leads to migration failure.

Signed-off-by: Pavel Vokhmyanin <pvokhmyanin at virtuozzo.com>
Signed-off-by: Cyrill Gorcunov <gorcunov at gmail.com>
---
 phaul/p_haul_vz.py | 49 ++++++++++++++++++++++++++++++++++---------------
 1 file changed, 34 insertions(+), 15 deletions(-)

diff --git a/phaul/p_haul_vz.py b/phaul/p_haul_vz.py
index a7dacd8..9f66da7 100644
--- a/phaul/p_haul_vz.py
+++ b/phaul/p_haul_vz.py
@@ -23,18 +23,16 @@ cgexec_bin = "cgexec"
 
 
 vz_cgroup_mount_map = {
-	"/sys/fs/cgroup/cpu,cpuacct": "cpu",
-	"/sys/fs/cgroup/cpuset": "cpuset",
-	"/sys/fs/cgroup/net_cls": "net_cls",
-	"/sys/fs/cgroup/memory": "memory",
-	"/sys/fs/cgroup/devices": "devices",
-	"/sys/fs/cgroup/blkio": "blkio",
-	"/sys/fs/cgroup/freezer": "freezer",
-	"/sys/fs/cgroup/beancounter": "beancounter",
-	"/sys/fs/cgroup/ve": "ve",
-	"/sys/fs/cgroup/perf_event": "perf_event",
-	"/sys/fs/cgroup/hugetlb": "hugetlb",
-	"/sys/fs/cgroup/systemd": "systemd",
+	"cpu,cpuacct": "cpu",
+	"cpuset": "cpuset",
+	"net_cls": "net_cls",
+	"memory": "memory",
+	"devices": "devices",
+	"blkio": "blkio",
+	"freezer": "freezer",
+	"perf_event": "perf_event",
+	"hugetlb": "hugetlb",
+	"systemd": "systemd",
 }
 
 
@@ -129,7 +127,6 @@ class p_haul_type(object):
 
 	def adjust_criu_req(self, req):
 		"""Add module-specific options to criu request"""
-
 		# Specify dump specific options
 		if req.type == pycriu.rpc.DUMP:
 
@@ -140,8 +137,7 @@ class p_haul_type(object):
 			req.opts.manage_cgroups = True
 
 			# Setup mapping for external Virtuozzo specific cgroup mounts
-			for key, value in vz_cgroup_mount_map.items():
-				req.opts.ext_mnt.add(key=key, val=value)
+			self.__fill_vz_cgroup_ext_mount_map(req)
 
 			# Specify secondary ploop disks as external
 			disks = self.__parse_secondary_disks_arg(self.__secondary_disks)
@@ -162,6 +158,29 @@ class p_haul_type(object):
 			# Increase timeout up to 180 seconds
 			req.opts.timeout = 180
 
+	def __fill_vz_cgroup_ext_mount_map(self, req):
+		with open("/proc/self/mountinfo") as x:
+			mountinfo = x.readlines()
+		# Walk cgroups maps
+		for cgkey in vz_cgroup_mount_map:
+
+			# If key consists of two cgroups (e.g."cpu,cpuacct"), walk each
+			for cgname in cgkey.split(","):
+
+				# Substite "systemd" with "name=systemd" option
+				if cgname == "systemd":
+					cgname = "name=systemd"
+
+				# Iterate through lines in mountinfo until we find a match
+				for buf in mountinfo:
+					mi_line = buf.split()
+					if mi_line[8] != "cgroup":
+						continue
+					if cgname in mi_line[10].split(","):
+						req.opts.ext_mnt.add(key = mi_line[4],
+								val = vz_cgroup_mount_map[cgkey])
+						break
+
 	def root_task_pid(self):
 		path = "/var/run/ve/{0}.init.pid".format(self._ctid)
 		with open(path) as pidfile:
-- 
2.7.4