Re: [pve-devel] [PATCH pve-storage] fix #1611: implement import of base-images for LVM-thin Storage

["Hannes Dürr" <h.duerr@proxmox.com>]

On 11/3/23 11:39, Fiona Ebner wrote:
[...]
> This essentially duplicates most of the same function in the parent
> plugin, i.e. LVMPlugin. What you can do to avoid it, is introduce new
> helper functions for the parts that are different, call those in
> LVMPlugin's implementation and overwrite the helpers appropriately in
> LvmThinPlugin. Then call the parent plugin's function here and do the
> base conversion at the end.
yes makes sense to work with the LVMPlugin implementation
rather then duplicating all the code, good point.
>> +sub volume_import {
> (...)
>
>> +
>> +    # Request new vm-name which is needed for the import
>> +    if ($isBase) {
>> +	my $newvmname = $class->find_free_diskname($storeid, $scfg, $vmid);
>> +	$name = $newvmname;
>> +	$volname = $newvmname;
>> +    }
> So this is one of the parts that needs to be different.
>
> You could also just set the name to undef and alloc_image will call
> find_free_diskname itself. Might be slightly nicer and avoids a new
> find_free_diskname call. We could also set the name to vm-XYZ-disk-N
> instead of base-XYZ-disk-N for the allocation I think. Or the whole
> function could even be:
>
> 1. check if base
> 2. check if already exists/rename allowed
> 3. call parent plugin's volume_import function passing along
> vm-XYZ-disk-N (or undef if it should be renamed) instead of base-XYZ-disk-N
> 4. if it was a base image, handle the conversion to base image
>
> Then there's no need for new helpers either. But this is just a sketch
> of course, didn't think through all details. What do you think?
that sounds good so far, but you can't get around the 
"find_free_diskspace()" call, can you ?
Not specifying a name leads to an error in the volume_import of the LVM 
plugin,
because without a name no plugin can be parsed and to get a new name in 
the style
of "vm-XYZ-disk-N" you need "find_free_diskspace()" to make sure that 
the name does not yet exist,
or am I missing something ?

So I'd propose:

1. check if base
2. check if already exists/rename allowed
3. call parent plugin's volume_import function passing along
vm-XYZ-disk-N generated with "find_free_diskspace(), instead of 
base-XYZ-disk-N
4. if it was a base image, handle the conversion to base image