On Tue, Jul 15, 2025 at 03:38:57PM +0000, DERUMIER, Alexandre via pve-devel
wrote:
> From: "DERUMIER, Alexandre" <alexandre.derum...@groupe-cyllene.com>
> To: "w.bumil...@proxmox.com" <w.bumil...@proxmox.com>
> CC: "pve-devel@lists.proxmox.com" <pve-devel@lists.proxmox.com>,
> "t.lampre...@proxmox.com" <t.lampre...@proxmox.com>,
> "f.gruenbich...@proxmox.com" <f.gruenbich...@proxmox.com>
> Subject: Re: [pve-devel] [PATCH pve-storage 09/13] storage: add
> volume_support_qemu_snapshot
> Date: Tue, 15 Jul 2025 15:38:57 +0000
> Message-ID:
> <82c18a632e730b7c18a93aacd9f4d623d56061be.ca...@groupe-cyllene.com>
>
> >>Yeah I tried some quick tests and it seems to be a bit tricky. Or
> >>maybe
> >>I just missed something.
>
> Just have done fast tests, I think I have found a way.
> (I'll do more test tomorrow to see if everything is ok in guest)
>
>
>
> sub qemu_volume_snapshot {
> my ($vmid, $deviceid, $storecfg, $drive, $snap) = @_;
> .....
>
> } elsif ($do_snapshots_type eq 'external') {
> my $storeid = (PVE::Storage::parse_volume_id($volid))[0];
> my $scfg = PVE::Storage::storage_config($storecfg, $storeid);
> print "external qemu snapshot\n";
> my $snapshots = PVE::Storage::volume_snapshot_info($storecfg,
> $volid);
> my $parent_snap = $snapshots->{'current'}->{parent};
> my $machine_version =
> PVE::QemuServer::Machine::get_current_qemu_machine($vmid);
>
> #no rename here anymore
>
> PVE::QemuServer::Blockdev::blockdev_external_snapshot(
> $storecfg, $vmid, $machine_version, $deviceid, $drive,
> $snap, $parent_snap
> );
> ...
> }
>
>
> sub blockdev_external_snapshot {
> my ($storecfg, $vmid, $machine_version, $deviceid, $drive, $snap,
> $parent_snap) = @_;
>
> print "Creating a new current volume with $snap as backing snap\n";
>
> my $volid = $drive->{file};
>
> #rename current to snap && preallocate add a new current file with
> reference to snapbacking-file, we can remove the $running param
>
> my $running = undef
> PVE::Storage::volume_snapshot($storecfg, $volid, $snap, undef);
>
> #call the blockdev_rename, only to reopen internal blockdev current
> active image to snap volname
>
> my $skip_volume_rename=1;
> #reopen current to snap
> PVE::QemuServer::Blockdev::blockdev_rename(
> $storecfg,
> $vmid,
> $machine_version,
> $deviceid,
> $drive,
> 'current',
> $snap,
> $parent_snap,
> $skip_volume_rename
> );
>
> ###the rest is the same than before
>
> #be sure to add drive in write mode
> delete($drive->{ro});
>
> my $new_file_blockdev = generate_file_blockdev($storecfg, $drive);
> my $new_fmt_blockdev = generate_format_blockdev($storecfg, $drive,
> $new_file_blockdev);
>
> my $snap_file_blockdev = generate_file_blockdev($storecfg, $drive,
> $snap);
> my $snap_fmt_blockdev = generate_format_blockdev(
> $storecfg,
> $drive,
> $snap_file_blockdev,
> { 'snapshot-name' => $snap },
> );
>
>
> #backing need to be forced to undef in blockdev, to avoid reopen of
> backing-file on blockdev-add
> $new_fmt_blockdev->{backing} = undef;
>
> mon_cmd($vmid, 'blockdev-add', %$new_fmt_blockdev);
>
> mon_cmd(
> $vmid, 'blockdev-snapshot',
> node => $snap_fmt_blockdev->{'node-name'},
> overlay => $new_fmt_blockdev->{'node-name'},
> );
> }
seems to work - at least on my lvm tests
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