[pve-devel] applied: [PATCH qemu-server] fix #2258: select correct device when removing drive snapshot via QEMU

[Fabian Grünbichler]

with a small cleanup as follow-up, as discussed off-list.

thanks!

On January 3, 2024 2:41 pm, Fiona Ebner wrote:
> The QMP command needs to be issued for the device where the disk is
> currently attached, not for the device where the disk was attached at
> the time the snapshot was taken.
> 
> Fixes the following scenario with a disk image for which
> do_snapshots_with_qemu() is true (i.e. qcow2 or RBD+krbd=0):
> 1. Take snapshot while disk image is attached to a given bus+ID.
> 2. Detach disk image.
> 3. Attach disk image to a different bus+ID.
> 4. Remove snapshot.
> 
> Previously, this would result in an error like:
>> blockdev-snapshot-delete-internal-sync' failed - Cannot find device=drive-scsi1 nor node_name=drive-scsi1
> 
> While the $running parameter for volume_snapshot_delete() is planned
> to be removed on the next storage plugin APIAGE reset, it currently
> causes an immediate return in Storage/Plugin.pm. So passing a truthy
> value would prevent removing a snapshot from an unused qcow2 disk that
> was still used at the time the snapshot was taken. Thus, and because
> some exotic third party plugin might be using it for whatever reason,
> it's necessary to keep passing the same value as before.
> 
> Signed-off-by: Fiona Ebner <f.ebner at proxmox.com>
> ---
> 
> Nicer to read with a word-based diff e.g.:
> git log -p -w --word-diff=color --word-diff-regex='\w+'
> 
>  PVE/QemuServer.pm | 19 ++++++++++++-------
>  1 file changed, 12 insertions(+), 7 deletions(-)
> 
> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
> index 3b1540b6..82b78fa5 100644
> --- a/PVE/QemuServer.pm
> +++ b/PVE/QemuServer.pm
> @@ -4754,21 +4754,26 @@ sub qemu_volume_snapshot_delete {
>      my ($vmid, $deviceid, $storecfg, $volid, $snap) = @_;
>  
>      my $running = check_running($vmid);
> +    my $attached_deviceid;
>  
> -    if($running) {
> -
> -	$running = undef;
> +    if ($running) {
>  	my $conf = PVE::QemuConfig->load_config($vmid);
>  	PVE::QemuConfig->foreach_volume($conf, sub {
>  	    my ($ds, $drive) = @_;
> -	    $running = 1 if $drive->{file} eq $volid;
> +	    $attached_deviceid = "drive-$ds" if $drive->{file} eq $volid;
>  	});
>      }
>  
> -    if ($running && do_snapshots_with_qemu($storecfg, $volid, $deviceid)) {
> -	mon_cmd($vmid, 'blockdev-snapshot-delete-internal-sync', device => $deviceid, name => $snap);
> +    if ($attached_deviceid && do_snapshots_with_qemu($storecfg, $volid, $attached_deviceid)) {
> +	mon_cmd(
> +	    $vmid,
> +	    'blockdev-snapshot-delete-internal-sync',
> +	    device => $attached_deviceid,
> +	    name => $snap,
> +	);
>      } else {
> -	PVE::Storage::volume_snapshot_delete($storecfg, $volid, $snap, $running);
> +	PVE::Storage::volume_snapshot_delete(
> +	    $storecfg, $volid, $snap, $attached_deviceid ? 1 : undef);
>      }
>  }
>  
> -- 
> 2.39.2
> 
> 
> 
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