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

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Message-Id: <20230811143929.79ee3231cbcdfbe43852a4bf@linux-foundation.org>
Date:   Fri, 11 Aug 2023 14:39:29 -0700
From:   Andrew Morton <akpm@...ux-foundation.org>
To:     Mike Rapoport <rppt@...nel.org>
Cc:     Kemeng Shi <shikemeng@...weicloud.com>, 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

On Thu, 20 Jul 2023 08:37:36 +0300 Mike Rapoport <rppt@...nel.org> wrote:

> 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 added this to the [0/N]:

: Benefits include:
: 
: 1. Future clients can call page_ext_data directly instead of defining
:    a new function like get_page_owner to get the data.
: 
: 2. There is no change to clients if the layout of page_ext data changes.

Mike, what is your position on this patchset now?

Thanks.