Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20;
Date:   Mon, 17 Jul 2023 14:34:26 +0100
From:   Matthew Wilcox <willy@infradead.org>
To:     Peng Zhang <zhangpeng362@huawei.com>
Cc:     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 1/6] mm/page_io: use a folio in __end_swap_bio_read()
Message-ID: <ZLVDYjdflF+3oJCG@casper.infradead.org>
References: <20230717132602.2202147-1-zhangpeng362@huawei.com>
 <20230717132602.2202147-2-zhangpeng362@huawei.com>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <20230717132602.2202147-2-zhangpeng362@huawei.com>
Precedence: bulk

On Mon, Jul 17, 2023 at 09:25:57PM +0800, Peng Zhang wrote:
> +++ b/mm/page_io.c
> @@ -58,18 +58,18 @@ static void end_swap_bio_write(struct bio *bio)
>  
>  static void __end_swap_bio_read(struct bio *bio)
>  {
> -	struct page *page = bio_first_page_all(bio);
> +	struct folio *folio = page_folio(bio_first_page_all(bio));

Should we have a bio_first_folio_all()?  It wouldn't save any calls to
compound_head(), but it's slightly easier to use.

>  	if (bio->bi_status) {
> -		SetPageError(page);
> -		ClearPageUptodate(page);
> +		folio_set_error(folio);

I appreciate this is a 1:1 conversion, but maybe we could think about
this a bit.  Is there anybody who checks the
PageError()/folio_test_error() for this page/folio?

> +		folio_clear_uptodate(folio);

Similarly ... surely the folio is already !uptodate, so we don't need to
clear the flag?