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From: Daniel Gomez <da.gomez@samsung.com>
To: Matthew Wilcox <willy@infradead.org>
CC: Christoph Hellwig <hch@lst.de>, Trond Myklebust
	<trond.myklebust@hammerspace.com>, Anna Schumaker <anna@kernel.org>,
	"linux-nfs@vger.kernel.org" <linux-nfs@vger.kernel.org>,
	"linux-fsdevel@vger.kernel.org" <linux-fsdevel@vger.kernel.org>,
	"linux-mm@kvack.org" <linux-mm@kvack.org>
Subject: Re: [PATCH 1/2] filemap: Convert generic_perform_write() to support
 large folios
Thread-Topic: [PATCH 1/2] filemap: Convert generic_perform_write() to
	support large folios
Thread-Index: AQHasRMEv8C0Tteo9UiuY4wdfWDY+LGsy3MAgAAklwA=
Date: Tue, 28 May 2024 19:01:43 +0000
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References: <20240527163616.1135968-1-hch@lst.de>
	<20240527163616.1135968-2-hch@lst.de>
	<CGME20240528152340eucas1p17ba2ad78d8ea869ef44cdeedb2601f80@eucas1p1.samsung.com>
	<gh7wdpeqorbtvbywigkzy3fakb7a4e46y6h6nrusn6rmup6yfm@2rjq4ltwmdq4>
	<ZlYLZDG_D74AtW5M@casper.infradead.org>

On Tue, May 28, 2024 at 05:50:44PM +0100, Matthew Wilcox wrote:
> On Tue, May 28, 2024 at 03:23:39PM +0000, Daniel Gomez wrote:
> > I have the same patch for shmem and large folios tree. That was the las=
t piece
> > needed for getting better performance results. However, it is also need=
ed to
> > support folios in the write_begin() and write_end() callbacks.
>=20
> I don't think it's *needed*.  It's nice!  But clearly not necessary
> since Christoph made nfs work without doing that.

I see. We send anyway the length with bytes and the folio allocated inside
write_begin() is retrieved with folio_page().

I did test this patch (+mapping_max_folio_size() patch) for shmem an it wor=
ks fine for me.
>=20
> > In order to avoid
> > making them local to shmem, how should we do the transition to folios i=
n these
> > 2 callbacks? I was looking into aops->read_folio approach but what do y=
ou think?
>=20
> See the v2 of buffer_write_operations that I just posted.  I was waiting
> for feedback from Christoph on the revised method for passing fsdata
> around, but I may as well just post a v2 and see what happens.

Interesting. I think it makes sense to convert tmpfs to
buffered_write_operations as well. Can you add me to the v2 so I can add/re=
view
it for tmpfs?

Thanks=