[libvirt] [PATCH v2] qemu: don't check for backing chains for formats w/o snapshot support

[Martin Kletzander]

On Thu, Apr 24, 2014 at 12:45:52PM +0200, Jiri Denemark wrote:
>On Thu, Apr 24, 2014 at 12:32:01 +0200, Martin Kletzander wrote:
>> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1019926
>> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=868673
>>
>> Signed-off-by: Martin Kletzander <mkletzan at redhat.com>
>> ---
>>
>> Notes:
>>     Smaller and cleaner variant of v1 [1] after discussion with Eric
>>
>>     [1] https://www.redhat.com/archives/libvir-list/2014-April/msg00716.html
>>
>>  src/qemu/qemu_domain.c | 5 ++++-
>>  1 file changed, 4 insertions(+), 1 deletion(-)
>>
>> diff --git a/src/qemu/qemu_domain.c b/src/qemu/qemu_domain.c
>> index 45ed872..5687075 100644
>> --- a/src/qemu/qemu_domain.c
>> +++ b/src/qemu/qemu_domain.c
>> @@ -2268,11 +2268,14 @@ qemuDomainCheckDiskPresence(virQEMUDriverPtr driver,
>>      VIR_DEBUG("Checking for disk presence");
>>      for (i = vm->def->ndisks; i > 0; i--) {
>>          disk = vm->def->disks[i - 1];
>> +        enum virStorageFileFormat format = virDomainDiskGetFormat(disk);
>>
>>          if (!virDomainDiskGetSource(disk))
>>              continue;
>>
>> -        if (qemuDomainDetermineDiskChain(driver, vm, disk, false) >= 0 &&
>> +        if ((format < VIR_STORAGE_FILE_NONE ||
>> +             format >= VIR_STORAGE_FILE_BACKING) &&
>> +            qemuDomainDetermineDiskChain(driver, vm, disk, false) >= 0 &&
>>              qemuDiskChainCheckBroken(disk) >= 0)
>>              continue;
>
>Better than the original but still... wouldn't it be better to move the
>check to qemuDomainDetermineDiskChain or even virStorageFileGetMetadata,
>where we could even use fileTypeInfo[format].getBackingStore as a base
>for the decision?
>

This particular skip is intended precisely for this situation and
should not affect any disk chain determination nor should it disable
the possibility of getting metadata of images without backing support,
so I believe this is the best approach for that.  However, since this
patch is not applicable anymore, I'll send a v3 in a minute.

Martin
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