[PATCH v2 2/2] qemu: Tell secdrivers which images are top parent

[Michal Privoznik]

On 3/9/20 10:18 AM, Peter Krempa wrote:
> On Mon, Mar 09, 2020 at 09:29:43 +0100, Michal Privoznik wrote:
>> When preparing images for block jobs we modify their seclabels so
>> that QEMU can open them. However, as mentioned in the previous
>> commit, secdrivers base some it their decisions whether the image
>> they are working on is top of of the backing chain. Fortunately,
>> in places where we call secdrivers we know this and the
>> information can be passed to secdrivers.
>>
>> The problem is the following: after the first blockcommit from
>> the base to one of the parents the XATTRs on the base image are
>> not cleared and therefore the second attempt to do another
>> blockcommit fails. This is caused by blockcommit code calling
>> qemuSecuritySetImageLabel() over the base image, possibly
>> multiple times (to ensure RW/RO access). A naive fix would be to
>> call the restore function. But this is not possible, because that
>> would deny QEMU the access to the base image.  Fortunately, we
>> can use the fact that seclabels are remembered only for the top
>> of the backing chain and not for the rest of the backing chain.
>> And thanks to the previous commit we can tell secdrivers which
>> images are top of the backing chain.
>>
>> Resolves: https://bugzilla.redhat.com/show_bug.cgi?id=1803551
>>
>> Signed-off-by: Michal Privoznik <mprivozn at redhat.com>
>> ---
> 
> Once you fix all of the wrong variable name in this patch as well as in
> the previous one:

Does isParentChainTop sound good for the variable name?

Michal