Re: [pve-devel] [PATCH qemu-server 2/3] migrate: always check if content type images is available for target storage

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

On March 22, 2021 9:56 am, Fabian Ebner wrote:
> Am 19.03.21 um 15:16 schrieb Fabian Grünbichler:
>> On March 19, 2021 2:49 pm, Fabian Ebner wrote:
>>> it's cheap and saves code.
>> 
>> but also changes behaviour in a non-backwards-compatible fashion.
>> 
>> previously, if a disk was already on a storage that does not have images
>> configured, and the migration leaves it on that storage, this config
>> mismatch was ignored (hence the "grandfather in existing mismatches"
>> comment). note that users might be able to migrate, but not able to
>> change storage.cfg to fix this "misconfiguration".
>> 
> 
> What about the recent change [0] in pve-storage then, i.e. not listing 
> VM disks for storages without an appropriate content type?

I'd have to think more about that (I mean, it obviously makes sense, the 
question is whether it breaks something ;))

> 
> I'd argue that unreferenced images that lie on storages without an 
> 'image' content type should not be picked up in the first place. If we 
> don't agree on this, then [0] needs to be reverted...

but this is not just about unreferenced disks? I mean, this code runs 
for ALL disks returned by pve-storage. if pve-storage now filters, then 
this does not apply for the '"old == new" storage which has wrong content 
type' scenario, since this part of the code thinks there are no volumes 
there, so what I originally thought is broken is not,

> If we do agree on this, we should double down on [0] and actually be 
> precise about the content type in vdisk_list by either:
>      A) adding a content/guest type parameter to vdisk_list.
>      B) adapting the call sites to filter storages.
> Afterwards, this patch could be applied with the appropriate dependency 
> bump ;)
> 
> Note that referenced unused images will still be picked up by the 
> PVE::QemuServer::foreach_volid iteration, no matter what the content 
> type of their storage is.

but this would then mean that for referenced images, '"old != new" 
storage where both old and new storage have wrong content type' now 
suddenly works where it previously didn't? not because of this patch, 
but because of vdisk_list not returning those, thus skipping the check 
that is changed in this patch? oh, and shared storages with wrong 
content type also just work, but since we don't really touch volumes 
there anyway with migration that's probably fine..

IFF we want to say "wrong content type" is wrong and should make the VM 
unmigratable, we should probably move the check into test_volid so that 
it catches ALL volumes always..

> 
> [0]: 
> https://git.proxmox.com/?p=pve-storage.git;a=commit;h=a44c18925d223a971296801a0985db34707ada4d
> 
>>>
>>> Signed-off-by: Fabian Ebner <f.ebner@proxmox.com>
>>> ---
>>>   PVE/QemuMigrate.pm | 7 ++-----
>>>   1 file changed, 2 insertions(+), 5 deletions(-)
>>>
>>> diff --git a/PVE/QemuMigrate.pm b/PVE/QemuMigrate.pm
>>> index 3597cc9..44cecce 100644
>>> --- a/PVE/QemuMigrate.pm
>>> +++ b/PVE/QemuMigrate.pm
>>> @@ -410,11 +410,8 @@ sub sync_disks {
>>>   	    $log_error->("storage '$targetsid' is not available on node '$self->{node}'")
>>>   		if !$target_scfg;
>>>   
>>> -	    # grandfather in existing mismatches
>>> -	    if ($targetsid ne $storeid && $target_scfg) {
>>> -		$log_error->("content type 'images' is not available on storage '$targetsid'")
>>> -		    if !$target_scfg->{content}->{images};
>>> -	    }
>>> +	    $log_error->("content type 'images' is not available on storage '$targetsid'")
>>> +		if $target_scfg && !$target_scfg->{content}->{images};
>>>   
>>>   	    PVE::Storage::foreach_volid($dl, sub {
>>>   		my ($volid, $sid, $volinfo) = @_;
>>> -- 
>>> 2.20.1
>>>
>>>
>>>
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>>>
>>>
>> 
>> 
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