[dm-devel] [PATCH 3/4] dm-zoned: V2 metadata handling

[John Dorminy]

That does make sense. May I request, then, using UUID_SIZE instead of 16?
Perhaps with a compile-time assertion that UUID_SIZE has not change from 16?

On Thu, Apr 2, 2020 at 11:10 AM Hannes Reinecke <hare at suse.de> wrote:

> On 4/2/20 4:53 PM, John Dorminy wrote:
> > I'm worried about hardcoding uuid members as u8[16].
> >
> > May I ask why you're not using uuid_t to define it in the on-disk
> > structure? It would save the casting of the uuid members to (uuid_t *)
> > every time you use a uuid.h function.
> >
> > Possibly it is customary to use only raw datatypes on disk rather than
> > opaque types like uuid_t, I'm not sure. But in that case, perhaps using
> > the named constant UUID_SIZE instead of 16 would make the meaning
> clearer?
> >
> I prefer to use absolute types (like __u8) when describing the on-disk
> format.
> When using opaque types like uuid_t there always is the risk that the
> internal representation will change, leading to an involuntary change of
> the on-disk format structure and subsequent compability issues.
>
> Cheers,
>
> Hannes
> --
> Dr. Hannes Reinecke            Teamlead Storage & Networking
> hare at suse.de                               +49 911 74053 688
> SUSE Software Solutions GmbH, Maxfeldstr. 5, 90409 Nürnberg
> HRB 36809 (AG Nürnberg), Geschäftsführer: Felix Imendörffer
>
>
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