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: <mvfcwyv5vkmsv52jh2gq4u7vjzqiyfal4pu2yawzunjjqv44vt@qgvepto6vr4j>
Date: Thu, 19 Jun 2025 17:08:27 +0200
From: Jan Kara <jack@...e.cz>
To: Zhang Yi <yi.zhang@...weicloud.com>
Cc: linux-ext4@...r.kernel.org, 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, libaokun1@...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 Wed 11-06-25 19:16:20, 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>

Indeed. Feel free to add:

Reviewed-by: Jan Kara <jack@...e.cz>

								Honza

> ---
>  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;
>  }
> -- 
> 2.46.1
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR