Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Subject: Re: [PATCH v14 076/138] mm/writeback: Add
 folio_redirty_for_writepage()
To:     "Matthew Wilcox (Oracle)" <willy@infradead.org>,
        linux-kernel@vger.kernel.org
Cc:     linux-mm@kvack.org, linux-fsdevel@vger.kernel.org,
        Christoph Hellwig <hch@lst.de>
References: <20210715033704.692967-1-willy@infradead.org>
 <20210715033704.692967-77-willy@infradead.org>
From:   Vlastimil Babka <vbabka@suse.cz>
Message-ID: <249863ea-8b4b-df38-545a-5f083502270d@suse.cz>
Date:   Thu, 12 Aug 2021 18:30:51 +0200
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.12.0
MIME-Version: 1.0
In-Reply-To: <20210715033704.692967-77-willy@infradead.org>
Content-Type: text/plain; charset=utf-8
Content-Language: en-US
Content-Transfer-Encoding: 7bit
Precedence: bulk

On 7/15/21 5:36 AM, Matthew Wilcox (Oracle) wrote:
> Reimplement redirty_page_for_writepage() as a wrapper around
> folio_redirty_for_writepage().  Account the number of pages in the
> folio, add kernel-doc and move the prototype to writeback.h.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Reviewed-by: Christoph Hellwig <hch@lst.de>

Acked-by: Vlastimil Babka <vbabka@suse.cz>

Nit:

> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -2558,21 +2558,31 @@ void folio_account_redirty(struct folio *folio)
>  }
>  EXPORT_SYMBOL(folio_account_redirty);
>  
> -/*
> - * When a writepage implementation decides that it doesn't want to write this
> - * page for some reason, it should redirty the locked page via
> - * redirty_page_for_writepage() and it should then unlock the page and return 0
> +/**
> + * folio_redirty_for_writepage - Decline to write a dirty folio.
> + * @wbc: The writeback control.
> + * @folio: The folio.
> + *
> + * When a writepage implementation decides that it doesn't want to write
> + * @folio for some reason, it should call this function, unlock @folio and
> + * return 0.

s/0/false

> + *
> + * Return: True if we redirtied the folio.  False if someone else dirtied
> + * it first.
>   */
> -int redirty_page_for_writepage(struct writeback_control *wbc, struct page *page)
> +bool folio_redirty_for_writepage(struct writeback_control *wbc,
> +		struct folio *folio)
>  {
> -	int ret;
> +	bool ret;
> +	unsigned nr = folio_nr_pages(folio);
> +
> +	wbc->pages_skipped += nr;
> +	ret = filemap_dirty_folio(folio->mapping, folio);
> +	folio_account_redirty(folio);
>  
> -	wbc->pages_skipped++;
> -	ret = __set_page_dirty_nobuffers(page);
> -	account_page_redirty(page);
>  	return ret;
>  }
> -EXPORT_SYMBOL(redirty_page_for_writepage);
> +EXPORT_SYMBOL(folio_redirty_for_writepage);
>  
>  /**
>   * folio_mark_dirty - Mark a folio as being modified.
>