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Date:   Wed, 19 Jul 2023 22:34:36 -0700
From:   Christoph Hellwig <hch@infradead.org>
To:     Matthew Wilcox <willy@infradead.org>
Cc:     Peng Zhang <zhangpeng362@huawei.com>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org, sidhartha.kumar@oracle.com,
        akpm@linux-foundation.org, wangkefeng.wang@huawei.com,
        sunnanyong@huawei.com
Subject: Re: [PATCH v2 3/9] mm/page_io: convert bio_first_page_all() to
 bio_first_folio_all()
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On Wed, Jul 19, 2023 at 03:17:34PM +0100, Matthew Wilcox wrote:
> On Wed, Jul 19, 2023 at 05:58:42PM +0800, Peng Zhang wrote:
> > From: ZhangPeng <zhangpeng362@huawei.com>
> > 
> > Convert bio_first_page_all() to bio_first_folio_all() to return a
> > folio, which makes it easier to use.
> 
> This wasn't what I was suggesting.  Indeed, this may introduce bugs.
> I was suggesting adding bio_first_folio_all() so that it can be used
> by code that knows this is what it wants.

To add another opinion:  I'd really like to see bio_first_page_all
go away.  The right way to iterate over the pages is an iterator.
If we really want to micro-opimize not setting up an iteator because
we know we have exactly one page/folio just stash it into bi_private.