linux-kernel - Re: [PATCH 0/3] add page_ext_data to get client data in page

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Message-ID: <20230720053736.GM1901145@kernel.org>
Date:   Thu, 20 Jul 2023 08:37:36 +0300
From:   Mike Rapoport <rppt@...nel.org>
To:     Kemeng Shi <shikemeng@...weicloud.com>
Cc:     akpm@...ux-foundation.org, pasha.tatashin@...een.com,
        linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH 0/3] add page_ext_data to get client data in page_ext

Hi,

On Thu, Jul 20, 2023 at 10:38:39AM +0800, Kemeng Shi wrote:
> 
> on 7/19/2023 5:44 PM, Mike Rapoport wrote:
> > On Tue, Jul 18, 2023 at 10:58:09PM +0800, Kemeng Shi wrote:
> >> Current client get data from page_ext by adding offset which is auto
> >> generated in page_ext core and expose the data layout design insdie
> >> page_ext core. This series adds a page_ext_data to hide offset from
> >> client. Thanks!
> > 
> > Implementers of page_ext_operations are anyway intimately related to
> > page_ext, so I'm not convinced this has any value.
> >  
> Hi Mike, thanks for reply. I thinks page_ext_operations can be futher splited
> into public part which used by client to simply register and private part which
> only page_ext core cares and should not be accessed by client directly
> to reduce decoupling.

It would be easier to justify changes in this series if they were a part of
the refactoring you describe here.

> This series makes offset to be private which client
> doesn't really care to hide data layout inside page_ext core from client.
> There are some concrete gains I can list for now:
> 1. Future client cound call page_ext_data directly instead of define a
> new function like get_page_owner to get it's data.
> 2. No change to client if layout of page_ext data change.

These should be a part of the changelog.

> I hope this could be more convincing to you now.
> Thanks!
> 
> -- 
> Best wishes
> Kemeng Shi
> 

-- 
Sincerely yours,
Mike.