From 9f5f981914fa87ea01895016d217694d16fa526c Mon Sep 17 00:00:00 2001
From: Stoiko Ivanov <s.ivanov@proxmox.com>
Date: Mon, 5 Jul 2021 12:57:16 +0200
Subject: [PATCH] pve6to7: check for containers not supporting pure cgroupv2

Helpers copied from pve-container to avoid versioned bumps.

Early returns when no containers are running, or the containers don't
use systemd, as well as returning after finding the first affected
container to minimize impact and resource usage.

Checking running containers first since following /proc/<pid>/root is
cheaper than mounting all volumes for a container

Signed-off-by: Stoiko Ivanov <s.ivanov@proxmox.com>
---
 PVE/CLI/pve6to7.pm | 123 +++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 123 insertions(+)

diff --git a/PVE/CLI/pve6to7.pm b/PVE/CLI/pve6to7.pm
index 60edac11..b9aeb89c 100644
--- a/PVE/CLI/pve6to7.pm
+++ b/PVE/CLI/pve6to7.pm
@@ -23,6 +23,9 @@ use PVE::Tools qw(run_command split_list);
 use PVE::QemuConfig;
 use PVE::QemuServer;
 use PVE::VZDump::Common;
+use PVE::LXC;
+use PVE::LXC::Config;
+use PVE::LXC::Setup;
 
 use Term::ANSIColor;
 
@@ -891,6 +894,126 @@ sub check_storage_content {
     }
 }
 
+sub check_containers_cgroup_compat {
+
+    my $kernel_cli = PVE::Tools::file_get_contents('/proc/cmdline');
+    if ($kernel_cli =~ /systemd.unified_cgroup_hierarchy=0/){
+	log_skip("System explicitly configured for legacy hybrid cgroup hierarchy.");
+	return;
+    }
+
+    my $supports_cgroupv2 = sub {
+	my ($conf, $rootdir) = @_;
+
+	my $get_systemd_version = sub {
+	    my ($self) = @_;
+
+	    my $sd_lib_dir = -d "/lib/systemd" ? "/lib/systemd" : "/usr/lib/systemd";
+	    my $libsd = PVE::Tools::dir_glob_regex($sd_lib_dir, "libsystemd-shared-.+\.so");
+	    if (defined($libsd) && $libsd =~ /libsystemd-shared-(\d+)\.so/) {
+		return $1;
+	    }
+
+	    return undef;
+	};
+
+	my  $unified_cgroupv2_support = sub {
+	    my ($self) = @_;
+
+	    # https://www.freedesktop.org/software/systemd/man/systemd.html
+	    # systemd is installed as symlink to /sbin/init
+	    my $systemd = CORE::readlink('/sbin/init');
+
+	    # assume non-systemd init will run with unified cgroupv2
+	    if (!defined($systemd) || $systemd !~ m@/systemd$@) {
+		return 1;
+	    }
+
+	    # systemd version 232 (e.g. debian stretch) supports the unified hierarchy
+	    my $sdver = $get_systemd_version->();
+	    if (!defined($sdver) || $sdver < 232) {
+		return 0;
+	    }
+
+	    return 1;
+	};
+
+	my $ostype = $conf->{ostype};
+	if ($ostype eq 'devuan' || $ostype eq 'alpine') {
+	    return 1;
+	}
+
+	my $lxc_setup = PVE::LXC::Setup->new($conf, $rootdir);
+	return $lxc_setup->protected_call($unified_cgroupv2_support);
+    };
+
+    my $log_problem = sub {
+	my ($ctid) = @_;
+	log_warn("Found at least one CT ($ctid) which does not support running in a unified " .
+	    "cgroup v2 layout - either upgrade it or set systemd.unified_cgroup_hierarchy=0 " .
+	    "in the kernel cmdline - skipping further checks"
+	);
+    };
+
+    my $cts = eval { PVE::API2::LXC->vmlist({ node => $nodename }) };
+    if ($@) {
+	log_warn("Failed to retrieve information about this node's CTs - $@");
+	return;
+    }
+
+    if (!defined($cts) || !scalar(@$cts)) {
+	log_skip("No containers on node detected.");
+	return;
+    }
+
+    my @running_cts = grep { $_->{status} eq 'running' } @$cts;
+    my @offline_cts = grep { $_->{status} ne 'running' } @$cts;
+
+    for my $ct (@running_cts) {
+	my $ctid = $ct->{vmid};
+	my $pid = eval { PVE::LXC::find_lxc_pid($ctid) };
+	if (my $err = $@) {
+	    log_warn("Failed to get PID for running CT $ctid - $err");
+	    next;
+	}
+	my $rootdir = "/proc/$pid/root";
+	my $conf = PVE::LXC::Config->load_config($ctid);
+
+	my $ret = eval { $supports_cgroupv2->($conf, $rootdir) };
+	if (my $err = $@) {
+	    log_warn("Failed to get cgroup support status for CT $ctid - $err");
+	    next;
+	}
+	if (!$ret) {
+	    $log_problem->($ctid);
+	    return;
+	}
+    }
+
+    my $storage_cfg = PVE::Storage::config();
+    for my $ct (@offline_cts) {
+	my $ctid = $ct->{vmid};
+	my ($conf, $rootdir, $ret);
+	eval {
+	    $conf = PVE::LXC::Config->load_config($ctid);
+	    $rootdir = PVE::LXC::mount_all($ctid, $storage_cfg, $conf);
+	    $ret = $supports_cgroupv2->($conf, $rootdir);
+	};
+	if (my $err = $@) {
+	    log_warn("Failed to load config and mount CT $ctid - $err");
+	    eval { PVE::LXC::umount_all($ctid, $storage_cfg, $conf) };
+	    next;
+	}
+	if (!$ret) {
+	    $log_problem->($ctid);
+	    eval { PVE::LXC::umount_all($ctid, $storage_cfg, $conf) };
+	    last;
+	}
+
+	eval { PVE::LXC::umount_all($ctid, $storage_cfg, $conf) };
+    }
+};
+
 sub check_misc {
     print_header("MISCELLANEOUS CHECKS");
     my $ssh_config = eval { PVE::Tools::file_get_contents('/root/.ssh/config') };