linux-kernel - Re: [PATCH v2 1/6] ext4: move the calculation of wbc->nr_to_write to mpage_folio

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Message-ID: <50b9d0ce-df97-498f-8750-8a9e41a60f9c@huawei.com>
Date: Fri, 20 Jun 2025 09:51:08 +0800
From: Baokun Li <libaokun1@...wei.com>
To: Zhang Yi <yi.zhang@...weicloud.com>, <linux-ext4@...r.kernel.org>
CC: <linux-fsdevel@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
	<tytso@....edu>, <adilger.kernel@...ger.ca>, <jack@...e.cz>,
	<ojaswin@...ux.ibm.com>, <yi.zhang@...wei.com>, <yukuai3@...wei.com>,
	<yangerkun@...wei.com>
Subject: Re: [PATCH v2 1/6] ext4: move the calculation of wbc->nr_to_write to
 mpage_folio_done()

On 2025/6/11 19:16, Zhang Yi wrote:
> From: Zhang Yi <yi.zhang@...wei.com>
>
> mpage_folio_done() should be a more appropriate place than
> mpage_submit_folio() for updating the wbc->nr_to_write after we have
> submitted a fully mapped folio. Preparing to make mpage_submit_folio()
> allows to submit partially mapped folio that is still under processing.
>
> Signed-off-by: Zhang Yi <yi.zhang@...wei.com>
Makes sense. Feel free to add:

Reviewed-by: Baokun Li <libaokun1@...wei.com>
> ---
>   fs/ext4/inode.c | 7 ++++---
>   1 file changed, 4 insertions(+), 3 deletions(-)
>
> diff --git a/fs/ext4/inode.c b/fs/ext4/inode.c
> index be9a4cba35fd..3a086fee7989 100644
> --- a/fs/ext4/inode.c
> +++ b/fs/ext4/inode.c
> @@ -2024,7 +2024,10 @@ int ext4_da_get_block_prep(struct inode *inode, sector_t iblock,
>   
>   static void mpage_folio_done(struct mpage_da_data *mpd, struct folio *folio)
>   {
> -	mpd->first_page += folio_nr_pages(folio);
> +	unsigned long nr_pages = folio_nr_pages(folio);
> +
> +	mpd->first_page += nr_pages;
> +	mpd->wbc->nr_to_write -= nr_pages;
>   	folio_unlock(folio);
>   }
>   
> @@ -2055,8 +2058,6 @@ static int mpage_submit_folio(struct mpage_da_data *mpd, struct folio *folio)
>   	    !ext4_verity_in_progress(mpd->inode))
>   		len = size & (len - 1);
>   	err = ext4_bio_write_folio(&mpd->io_submit, folio, len);
> -	if (!err)
> -		mpd->wbc->nr_to_write -= folio_nr_pages(folio);
>   
>   	return err;
>   }