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

[Hannes Reinecke]

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
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