Re: [PATCH v5 07/31] qcow2: Document the Extended L2 Entries feature

[Alberto Garcia]

On Wed 06 May 2020 05:02:52 PM CEST, Alberto Garcia wrote:
>>> -                    With version 2, this is always 0.
>>> +                    With version 2 or with extended L2 entries (see the 
>>> next
>>> +                    section), this is always 0.
>>
>> In your cover letter, you said you changed things to tolerate this
>> bit being set even with extended L2 entries.  Does this sentence need
>> a tweak?
>
> Not a bad idea.

I just had a look at what happens with v2 images. There the bit is
actually checked and the image is marked corrupt, but that only seems to
happen in qcow2_get_host_offset(). You can write to a cluster that has
that bit set and QEMU won't complain (the bit is however cleared).

'qemu-img check' does not detect any inconsistency either.

As I said in my cover letter maybe it's worth preparing a separate
series that adds a QCOW2_CLUSTER_INVALID type and includes all these
cases.

Berto