Re: [pve-devel] [PATCH v3 storage 2/4] storage_migrate: pull out snapshot decision

["Fabian Grünbichler" <f.gruenbichler@proxmox.com>]

On January 5, 2022 10:00 am, Fabian Ebner wrote:
> Am 22.12.21 um 14:52 schrieb Fabian Grünbichler:
>> into new top-level helper for re-use with remote migration.
>> 
>> Signed-off-by: Fabian Grünbichler <f.gruenbichler@proxmox.com>
>> ---
>> new in v3
>> 
>>   PVE/Storage.pm | 14 ++++++++++----
>>   1 file changed, 10 insertions(+), 4 deletions(-)
>> 
>> diff --git a/PVE/Storage.pm b/PVE/Storage.pm
>> index 05be3dd..4f3a44a 100755
>> --- a/PVE/Storage.pm
>> +++ b/PVE/Storage.pm
>> @@ -643,6 +643,14 @@ my $volname_for_storage = sub {
>>       }
>>   };
>>   
>> +# whether a migration snapshot is needed for a given storage
>> +sub storage_migrate_snapshot {
>> +    my ($cfg, $storeid) = @_;
>> +    my $scfg = storage_config($cfg, $storeid);
>> +
>> +    return $scfg->{type} eq 'zfspool' || $scfg->{type} eq 'btrfs';
>> +}
>> +
>>   sub storage_migrate {
>>       my ($cfg, $volid, $target_sshinfo, $target_storeid, $opts, $logfunc) = @_;
>>   
>> @@ -688,10 +696,8 @@ sub storage_migrate {
>>   
>>       my $migration_snapshot;
>>       if (!defined($snapshot)) {
>> -	if ($scfg->{type} eq 'zfspool' || $scfg->{type} eq 'btrfs') {
>> -	    $migration_snapshot = 1;
>> -	    $snapshot = '__migration__';
>> -	}
>> +	$migration_snapshot = storage_migrate_snapshot->($cfg, $target_storeid);
> 
> The call is wrong, because of the ->

that's a fixup gone wrong (got cleaned up in a later patch instead of 
folding that chunk into this one)

> And why base the decision on the target storage rather than keeping it 
> based on the source storage? That breaks migration from e.g. lvm-thin to 
> btrfs, because it now tries to use a snapshot and doesn't find any 
> common transfer format anymore.

and yeah, this should be $storeid, not $target_storeid (ZFS only allows 
importing from ZFS, so it was not affected).

> 
>> +	$snapshot = '__migration__' if $migration_snapshot;
>>       }
>>   
>>       my @formats = volume_transfer_formats($cfg, $volid, $target_volid, $snapshot, $base_snapshot, $with_snapshots);
>