Re: [PATCH 3/6] xfs: use locality optimized cntbt lookups for near mode allocations

[Christoph Hellwig <hch@infradead.org>]

On Mon, May 13, 2019 at 11:45:44AM -0400, Brian Foster wrote:
> Hmm, I had attempted some tighter integration with the xfs_btree_cur on
> a previous variant and ran into some roadblocks, the details of which I
> don't recall. That said, I may have tried to include more than just this
> active state, ran into header issues, and then never really stepped back
> from that to explore more incremental changes.
> 
> I think extending the priv union with something for the allocation code
> to use makes sense. Your suggestion has me wondering if down the road we
> could genericize this further to a bc_valid state or some such that
> quickly indicates whether a cursor points at a valid record or off into
> space. That's a matter for another series however..

Yep.

> You mean to create tree specific cursor structures of which
> xfs_btree_cur is a member, then the tree specific logic uses
> container_of() to pull out whatever it needs from cur..? I'd need to
> think more about that one, but indeed that is beyond the scope of this
> work.

Yes.