[pve-devel] [PATCH v2 qemu-server] Fix block_resize qmp call for block devices

[Fabian Grünbichler]

On Thu, Jan 12, 2017 at 03:33:48PM +0300, Dmitry Petuhov wrote:
> Set zero size for backing block devices in qmp call. In that case qemu
> sets size of device in guest to current size of backing device, which
> was resized earlier. Otherwise, any non-zero value causes error here.

this is not clearly documented, but if PVE::Storage::volume_resize
returns 1, we assume the storage layer did not resize and qemu should do
the resizing

if it returns undef, we assume the storage resized the volume and we are
done.

so in the latter case, instead of returning in line 3983 we could set
$size to 0 (based on the return code of course ;)) and continue with the
running check and block_resize via monitor. this should only improve the
situation for all storages, without any wonky checks based on block
device or not.

the above semantic should be valid for all our plugins - I assume your
plugin returns 1 even if it did the resize operation (because otherwise
you would not send the monitor command..)? you'd need to change that..

(also please include the signoff if you send a new version!)

> 
> ---
>  PVE/QemuServer.pm | 6 ++++++
>  1 file changed, 6 insertions(+)
> 
> v2: fix typo -d instead of -b
> diff --git a/PVE/QemuServer.pm b/PVE/QemuServer.pm
> index bc26da2..3f53ac1 100644
> --- a/PVE/QemuServer.pm
> +++ b/PVE/QemuServer.pm
> @@ -3984,6 +3984,12 @@ sub qemu_block_resize {
>  
>      return if !$running;
>  
> +    my $path = PVE::Storage::path($cfg, $volid, undef);
> +    if ($path =~ m|^/|) {
> +        $path = abs_path($path);
> +        $size = 0 if -b $path;
> +    }
> +
>      vm_mon_cmd($vmid, "block_resize", device => $deviceid, size => int($size));
>  
>  }
> -- 
> 2.1.4
> 
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