[pve-devel] [PATCH qemu-server v2 3/6] implement suspend to disk for running vms

[Dominik Csapak]

the idea is to have the same logic as with snapshots, but without
the snapshotting of the disks, and after saving the vm state (incl memory),
we hard shut off the guest.

this way the disks will not be touched anymore by the guest

to prevent any alteration of the vm (incl migration, hw changes, etc) we
add a config lock 'suspend'

Signed-off-by: Dominik Csapak <d.csapak at proxmox.com>
---
changes from v1:
* handle backup lock better (abort in that case)
* use 'suspend-YYYY-MM-DD' as state name
* remove lock on error
* s/stat/state/
 PVE/QemuServer.pm | 77 ++++++++++++++++++++++++++++++++++++++++++++++++-------
 1 file changed, 68 insertions(+), 9 deletions(-)

diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
index 02bb798..3a54671 100644
--- a/PVE/QemuServer.pm
+++ b/PVE/QemuServer.pm
@@ -300,7 +300,7 @@ my $confdesc = {
 	optional => 1,
 	type => 'string',
 	description => "Lock/unlock the VM.",
-	enum => [qw(backup clone create migrate rollback snapshot snapshot-delete)],
+	enum => [qw(backup clone create migrate rollback snapshot snapshot-delete suspend)],
     },
     cpulimit => {
 	optional => 1,
@@ -5658,16 +5658,65 @@ sub vm_stop {
 }
 
 sub vm_suspend {
-    my ($vmid, $skiplock) = @_;
+    my ($vmid, $skiplock, $includestate) = @_;
 
     PVE::QemuConfig->lock_config($vmid, sub {
 
 	my $conf = PVE::QemuConfig->load_config($vmid);
 
+	my $is_backing_up = PVE::QemuConfig->has_lock($conf, 'backup');
 	PVE::QemuConfig->check_lock($conf)
-	    if !($skiplock || PVE::QemuConfig->has_lock($conf, 'backup'));
+	    if !($skiplock || $is_backing_up);
+
+	die "cannot suspend to disk during backup\n"
+	    if $is_backing_up && $includestate;
 
 	vm_mon_cmd($vmid, "stop");
+
+	if ($includestate) {
+	    $conf->{lock} = 'suspend';
+	    PVE::QemuConfig->write_config($vmid, $conf);
+
+	    # save vm state
+	    my $date = strftime("%Y-%m-%d", localtime(time()));
+	    my $storecfg = PVE::Storage::config();
+	    my $vmstate = prepare_save_vmstate($vmid, $conf, "suspend-$date", $storecfg, 1);
+	    my $path = PVE::Storage::path($storecfg, $vmstate);
+	    PVE::Storage::activate_volumes($storecfg, [$vmstate]);
+
+	    eval {
+		PVE::QemuServer::vm_mon_cmd($vmid, "savevm-start", statefile => $path);
+		for(;;) {
+		    my $state = PVE::QemuServer::vm_mon_cmd_nocheck($vmid, "query-savevm");
+		    if (!$state->{status}) {
+			die "savevm not active\n";
+		    } elsif ($state->{status} eq 'active') {
+			sleep(1);
+			next;
+		    } elsif ($state->{status} eq 'completed') {
+			last;
+		    } else {
+			die "query-savevm returned status '$state->{status}'\n";
+		    }
+		}
+	    };
+	    if (my $err = $@) {
+		# cleanup
+		warn $err;
+		eval {
+		    delete $conf->{lock};
+		    vm_mon_cmd($vmid, "savevm-end");
+		    PVE::Storage::deactivate_volumes($storecfg, [$vmstate]);
+		    PVE::Storage::vdisk_free($storecfg, $vmstate);
+		};
+		warn $@ if $@;
+		return;
+	    }
+
+	    # save changes and write config
+	    PVE::QemuConfig->write_config($vmid, $conf);
+	    vm_qmp_command($vmid, { execute => "quit" });
+	}
     });
 }
 
@@ -7101,9 +7150,7 @@ sub nbd_stop {
 }
 
 sub prepare_save_vmstate {
-    my ($vmid, $conf, $snapname, $storecfg) = @_;
-
-    my $snap = $conf->{snapshots}->{$snapname};
+    my ($vmid, $conf, $snapname, $storecfg, $suspend) = @_;
 
     # first, use explicitly configured storage
     my $target = $conf->{vmstatestorage};
@@ -7125,12 +7172,24 @@ sub prepare_save_vmstate {
 
     my $driver_state_size = 500; # assume 500MB is enough to safe all driver state;
     my $size = $conf->{memory}*2 + $driver_state_size;
+    my $scfg = PVE::Storage::storage_config($storecfg, $target);
 
     my $name = "vm-$vmid-state-$snapname";
-    my $scfg = PVE::Storage::storage_config($storecfg, $target);
     $name .= ".raw" if $scfg->{path}; # add filename extension for file base storage
-    $snap->{vmstate} = PVE::Storage::vdisk_alloc($storecfg, $target, $vmid, 'raw', $name, $size*1024);
-    $snap->{runningmachine} = PVE::QemuServer::get_current_qemu_machine($vmid);
+
+    my $statefile = PVE::Storage::vdisk_alloc($storecfg, $target, $vmid, 'raw', $name, $size*1024);
+    my $runningmachine = PVE::QemuServer::get_current_qemu_machine($vmid);
+
+    if ($suspend) {
+	$conf->{vmstate} = $statefile;
+	$conf->{runningmachine} = $runningmachine;
+    } else {
+	my $snap = $conf->{snapshots}->{$snapname};
+	$snap->{vmstate} = $statefile;
+	$snap->{runningmachine} = $runningmachine;
+    }
+
+    return $statefile;
 }
 
 # bash completion helper
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2.11.0