Re: [pve-devel] [PATCH qemu-server 07/31] backup: use blockdev for fleecing images

["Fabian Grünbichler" <f.gruenbichler@proxmox.com>]

On June 27, 2025 5:57 pm, Fiona Ebner wrote:
> Signed-off-by: Fiona Ebner <f.ebner@proxmox.com>
> ---
>  src/PVE/QemuConfig.pm          | 12 ++-------
>  src/PVE/QemuServer/Blockdev.pm | 45 +++++++++++++++++++++++++++++++---
>  src/PVE/VZDump/QemuServer.pm   | 26 ++++++++++++--------
>  3 files changed, 59 insertions(+), 24 deletions(-)
> 
> diff --git a/src/PVE/QemuConfig.pm b/src/PVE/QemuConfig.pm
> index 01104723..82295641 100644
> --- a/src/PVE/QemuConfig.pm
> +++ b/src/PVE/QemuConfig.pm
> @@ -10,6 +10,7 @@ use PVE::INotify;
>  use PVE::JSONSchema;
>  use PVE::QemuMigrate::Helpers;
>  use PVE::QemuServer::Agent;
> +use PVE::QemuServer::Blockdev;
>  use PVE::QemuServer::CPUConfig;
>  use PVE::QemuServer::Drive;
>  use PVE::QemuServer::Helpers;
> @@ -675,16 +676,7 @@ sub cleanup_fleecing_images {
>          };
>          $log_func->('warn', "checking/canceling old backup job failed - $@") if $@;
>  
> -        my $block_info = mon_cmd($vmid, "query-block");
> -        for my $info ($block_info->@*) {
> -            my $device_id = $info->{device};
> -            next if $device_id !~ m/-fleecing$/;
> -
> -            $log_func->('info', "detaching (old) fleecing image for '$device_id'");
> -            $device_id =~ s/^drive-//; # re-added by qemu_drivedel()
> -            eval { PVE::QemuServer::qemu_drivedel($vmid, $device_id) };
> -            $log_func->('warn', "error detaching (old) fleecing image '$device_id' - $@") if $@;
> -        }
> +        PVE::QemuServer::Blockdev::detach_fleecing_block_nodes($vmid, $log_func);
>      }
>  
>      PVE::QemuConfig->lock_config(
> diff --git a/src/PVE/QemuServer/Blockdev.pm b/src/PVE/QemuServer/Blockdev.pm
> index 8a991587..28a759a8 100644
> --- a/src/PVE/QemuServer/Blockdev.pm
> +++ b/src/PVE/QemuServer/Blockdev.pm
> @@ -14,8 +14,30 @@ use PVE::Storage;
>  use PVE::QemuServer::Drive qw(drive_is_cdrom);
>  use PVE::QemuServer::Monitor qw(mon_cmd);
>  
> +my sub fleecing_node_name {
> +    my ($type, $drive_id) = @_;
> +
> +    if ($type eq 'fmt') {
> +        return "drive-$drive_id-fleecing"; # this is the top node for fleecing
> +    } elsif ($type eq 'file') {
> +        return "$drive_id-fleecing-file"; # drop the "drive-" prefix to be sure, max length is 31

should we use `e-...` instead of `...-file`, to have similar encoding as
the regular block nodes? or even let get_node_name handle it by adding a
`top` type to it?

> +    }
> +
> +    die "unknown node type for fleecing '$type'";
> +}
> +
> +my sub is_fleecing_top_node {
> +    my ($node_name) = @_;
> +
> +    return $node_name =~ m/-fleecing$/ ? 1 : 0;
> +}
> +
>  my sub get_node_name {
> -    my ($type, $drive_id, $volid, $snap) = @_;
> +    my ($type, $drive_id, $volid, $options) = @_;
> +
> +    return fleecing_node_name($type, $drive_id) if $options->{fleecing};
> +
> +    my $snap = $options->{'snapshot-name'};
>  
>      my $info = "drive=$drive_id,";
>      $info .= "snap=$snap," if defined($snap);
> @@ -151,8 +173,7 @@ sub generate_file_blockdev {
>          $blockdev->{'detect-zeroes'} = PVE::QemuServer::Drive::detect_zeroes_cmdline_option($drive);
>      }
>  
> -    $blockdev->{'node-name'} =
> -        get_node_name('file', $drive_id, $drive->{file}, $options->{'snapshot-name'});
> +    $blockdev->{'node-name'} = get_node_name('file', $drive_id, $drive->{file}, $options);
>  
>      $blockdev->{'read-only'} = read_only_json_option($drive, $options);
>  
> @@ -185,7 +206,7 @@ sub generate_format_blockdev {
>          $format = $drive->{format} // 'raw';
>      }
>  
> -    my $node_name = get_node_name('fmt', $drive_id, $drive->{file}, $options->{'snapshot-name'});
> +    my $node_name = get_node_name('fmt', $drive_id, $drive->{file}, $options);
>  
>      my $blockdev = {
>          'node-name' => "$node_name",
> @@ -214,6 +235,8 @@ sub generate_drive_blockdev {
>      my $child = generate_file_blockdev($storecfg, $drive, $options);
>      $child = generate_format_blockdev($storecfg, $drive, $child, $options);
>  
> +    return $child if $options->{fleecing}; # for fleecing, this is already the top node
> +
>      # this is the top filter entry point, use $drive-drive_id as nodename
>      return {
>          driver => "throttle",
> @@ -354,4 +377,18 @@ sub detach {
>      return;
>  }
>  
> +sub detach_fleecing_block_nodes {
> +    my ($vmid, $log_func) = @_;
> +
> +    my $block_info = mon_cmd($vmid, "query-named-block-nodes");
> +    for my $info ($block_info->@*) {
> +        my $node_name = $info->{'node-name'};
> +        next if !is_fleecing_top_node($node_name);
> +
> +        $log_func->('info', "detaching (old) fleecing image '$node_name'");
> +        eval { detach($vmid, $node_name) };
> +        $log_func->('warn', "error detaching (old) fleecing image '$node_name' - $@") if $@;
> +    }
> +}
> +
>  1;
> diff --git a/src/PVE/VZDump/QemuServer.pm b/src/PVE/VZDump/QemuServer.pm
> index 243a927e..8b643bc4 100644
> --- a/src/PVE/VZDump/QemuServer.pm
> +++ b/src/PVE/VZDump/QemuServer.pm
> @@ -30,6 +30,7 @@ use PVE::Format qw(render_duration render_bytes);
>  use PVE::QemuConfig;
>  use PVE::QemuServer;
>  use PVE::QemuServer::Agent;
> +use PVE::QemuServer::Blockdev;
>  use PVE::QemuServer::Drive qw(checked_volume_format);
>  use PVE::QemuServer::Helpers;
>  use PVE::QemuServer::Machine;
> @@ -626,9 +627,8 @@ my sub detach_fleecing_images {
>  
>      for my $di ($disks->@*) {
>          if (my $volid = $di->{'fleece-volid'}) {
> -            my $devid = "$di->{qmdevice}-fleecing";
> -            $devid =~ s/^drive-//; # re-added by qemu_drivedel()
> -            eval { PVE::QemuServer::qemu_drivedel($vmid, $devid) };
> +            my $node_name = "$di->{qmdevice}-fleecing";
> +            eval { PVE::QemuServer::Blockdev::detach($vmid, $node_name) };
>          }
>      }
>  }
> @@ -646,15 +646,21 @@ my sub attach_fleecing_images {
>          if (my $volid = $di->{'fleece-volid'}) {
>              $self->loginfo("$di->{qmdevice}: attaching fleecing image $volid to QEMU");
>  
> -            my $path = PVE::Storage::path($self->{storecfg}, $volid);
> -            my $devid = "$di->{qmdevice}-fleecing";
> -            my $drive = "file=$path,if=none,id=$devid,format=$format,discard=unmap";
> +            my ($interface, $index) = PVE::QemuServer::Drive::parse_drive_interface($di->{virtdev});
> +            my $drive = {
> +                file => $volid,
> +                interface => $interface,
> +                index => $index,
> +                format => $format,
> +                discard => 'on',
> +            };
> +
> +            my $options = { 'fleecing' => 1 };
>              # Specify size explicitly, to make it work if storage backend rounded up size for
>              # fleecing image when allocating.
> -            $drive .= ",size=$di->{'block-node-size'}" if $format eq 'raw';
> -            $drive =~ s/\\/\\\\/g;
> -            my $ret = PVE::QemuServer::Monitor::hmp_cmd($vmid, "drive_add auto \"$drive\"", 60);
> -            die "attaching fleecing image $volid failed - $ret\n" if $ret !~ m/OK/s;
> +            $options->{size} = $di->{'block-node-size'} if $format eq 'raw';
> +
> +            PVE::QemuServer::Blockdev::attach($self->{storecfg}, $vmid, $drive, $options);
>          }
>      }
>  }
> -- 
> 2.47.2
> 
> 
> 
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