[pve-devel] [PATCH storage 15/26] common: add is_volume_type and is_type_change_allowed helpers

[Fabian Grünbichler]

On July 29, 2025 1:15 pm, Wolfgang Bumiller wrote:
> Generally we want to allow transitioning from 'images' or 'rootdir' to
> 'vm-vol' or 'ct-vol' respectively, but not the other way round.
> Obviously, staying *within* any of the types is also allowed.
> 
> The `is_volume_type` helper is just a convenience helper for
> functionality such as, for directory based storages, deciding whether
> a volume needs a VMID subdirectory.
> 
> Signed-off-by: Wolfgang Bumiller <w.bumiller at proxmox.com>
> ---
>  src/PVE/Storage/Common.pm | 42 +++++++++++++++++++++++++++++++++++++++
>  1 file changed, 42 insertions(+)
> 
> diff --git a/src/PVE/Storage/Common.pm b/src/PVE/Storage/Common.pm
> index bab1260..7086e1c 100644
> --- a/src/PVE/Storage/Common.pm
> +++ b/src/PVE/Storage/Common.pm
> @@ -313,4 +313,46 @@ sub should_list_images : prototype($$) ($expected_content_type, $volume_type) {
>      return $expected_content_type eq $volume_type;
>  }
>  
> +=head3 is_volume_type
> +
> +    is_volume_type($vtype)
> +
> +Returns true if C<$vtype> is C<images>, C<rootdir>, C<vm-vol> or C<ct-vol>.

then it should be called `vtype_is_vdisk`. the `v` in `vtype` stands for
`volume`, so every vtype is by definition a volume..

> +
> +Convenience helper to distinguish volume vtypes and content types from other types.
> +
> +=cut
> +
> +my %VOLUME_TYPE = map { $_ => 1 } qw(images vm-vol rootdir ct-vol);
> +
> +sub is_volume_type : prototype($) ($vtype) {
> +    return $VOLUME_TYPE{$vtype};
> +}
> +
> +=head3 is_type_change_allowed
> +
> +    is_type_change_allowed($source_vtype, $target_vtype)
> +
> +Returns true if a volume may change from C<$source_vtype> to C<$target_vtype>.
> +
> +This is generally allowed if the target vtype is equal or "more strict" than the source vtype. That
> +is, if the source vtype is not known, is C<"images">, or equal to C<$target_vtype>.
> +
> +Note that without a target vtype, only generic source vtypes (C<undef> or C<"images">) are allowed.
> +
> +=cut
> +
> +sub is_type_change_allowed : prototype($$) ($from, $to) {

this should probably be limited to vdisks?

> +    # If the source is unknown we don't care:
> +    return 1 if !defined($from);
> +
> +    # Likewise, if the source is "images" we don't actually know what it represents.
> +    return 1 if $from eq 'images';
> +
> +    # Otherwise if *both* are defined they must be equal.
> +    return 1 if defined($from) && defined($to) && $from eq $to; #
> +
> +    return undef;
> +}
> +
>  1;
> -- 
> 2.47.2
> 
> 
> 
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