[Gluster-devel] Readdir d_off encoding

[Jeff Darcy]

> An alternative would be to convert directories into regular files from
> the brick point of view.
> 
> The benefits of this would be:
> 
> * d_off would be controlled by gluster, so all bricks would have the
> same d_off and order. No need to use any d_off mapping or transformation.

I don't think a full-out change from real directories to virtual ones is
in the cards, but a variant of this idea might be worth exploring further.
If we had a *server side* component to map between on-disk d_off values
and those we present to clients, then it might be able to do a better job
than the local FS of ensuring uniqueness within the bits (e.g. 48 of them)
that are left over after we subtract some for a brick ID.  This could be
enough to make the bit-stealing approach (on the client) viable.  There
are probably some issues with failing over between replicas, which should
have the same files but might not have assigned the same internal d_off
values, but those issues might be avoidable if the d_off values are
deterministic with respect to GFIDs.