Re: [Qemu-devel] [PATCH v5 10/42] block: Use CAF in bdrv_is_encrypted()

[Max Reitz]

On 13.06.19 15:16, Vladimir Sementsov-Ogievskiy wrote:
> 13.06.2019 1:09, Max Reitz wrote:
>> bdrv_is_encrypted() should not only check the BDS's backing child, but
>> any filtered child: If a filter's child is encrypted, the filter node
>> itself naturally is encrypted, too.  Furthermore, we need to recurse
>> down the chain.
>>
>> (CAF means child access function.)
> 
> Hmm, so, if only one node in the backing chain is encrypted, all overlays,
> filters or not are considered encrypted too? Even if all the data is in top
> node and is not encrypted?
> 
> Checked that the function is used only for reporting through
> bdrv_query_image_info, which is called from bdrv_block_device_info() (which
> loops through backings), and from collect_image_info_list(), which loops 
> through
> backings if @chain=true.
> 
> And collect_image_info_list() is used only in img_info(), @chain is a mirrored
> --backing-chain parameter..
> 
> So, isn't it more correct to return exactly bs->encrypted in this function? 
> It will
> give more correct and informative results for queries for the whole chain.

Hm.  Maybe? :-)

I personally feel more comfortable to report more devices as being
reported than less.  The description of @encrypted in @BlockDeviceInfo
is vague enough that we can just “make it more precise”.

You’re right, it does sound more useful.

Max

signature.asc
Description: OpenPGP digital signature