Re: [PATCH qemu-server v2 2/4] agent: treat freeze-fs-on-backup as alias for guest-fsfreeze

[Fiona Ebner <f.ebner@proxmox.com>]

Am 25.03.26 um 10:34 PM schrieb Thomas Lamprecht:
> Alias the deprecated key to 'guest-fsfreeze' through the JSONSchema
> alias key support so consumers see a single, consistent value.
> Previously only the backup code path fell back to it, while snapshots,
> replications, clones and imports silently ignored it.
> 
> Note that while alias support for top-level JSON schema has a bug [0],
> the one for property strings - which this here is - works out fine.
> 
> [0]: https://lore.proxmox.com/all/20251205100317.1101549-1-d.csapak@proxmox.com/
> 
> The key stays in the schema indefinitely for old backup restore
> compatibility rather than being removed in a future major release.
> 

One potentially surprising thing (I guess another bug in JSONSchema?) is
that it's possible to set
qm set 100 --agent 1,freeze-fs=0,freeze-fs-on-backup=1
and the second option (which in this case is the deprecated one) will
then override the first when parsing. The check for duplicate keys
precedes the resolution of the alias in parse_property_string():

https://git.proxmox.com/?p=pve-common.git;a=blob;f=src/PVE/JSONSchema.pm;h=17e7126a6c42f8326a1da890680af10b6106d906;hb=17c6c3bdcf018756b4b48589b5485663103a9843#l1069

> Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>

Reviewed-by: Fiona Ebner <f.ebner@proxmox.com>

with two nits below:

---snip---

> @@ -77,6 +73,7 @@ sub parse_guest_agent {
>  
>      # if the agent is disabled ignore the other potentially set properties
>      return {} if !$res->{enabled};
> +
>      return $res;
>  }

Nit: unrelated change

>  
> diff --git a/src/PVE/VZDump/QemuServer.pm b/src/PVE/VZDump/QemuServer.pm
> index 0681661d..9f3cd191 100644
> --- a/src/PVE/VZDump/QemuServer.pm
> +++ b/src/PVE/VZDump/QemuServer.pm
> @@ -1108,11 +1108,7 @@ sub qga_fs_freeze {
>          return;
>      }
>  
> -    my $freeze = PVE::QemuServer::Agent::get_qga_key($conf, 'guest-fsfreeze');
> -    $freeze //= PVE::QemuServer::Agent::get_qga_key($conf, 'freeze-fs-on-backup');
> -    $freeze //= 1;
> -
> -    if (!$freeze) {
> +    if (!PVE::QemuServer::Agent::should_fs_freeze($self->{vmlist}->{$vmid})) {

Nit: could re-use $conf

>          $self->loginfo("skipping guest-agent 'fs-freeze', disabled in VM options");
>          return;
>      }