linux-ext4 - Re: [PATCH 08/10] mm: remove filemap_fdatawrite

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Message-ID: <2iplfhsl7b6nsq7nf6fhre2udcqeujph6mfg22afssqhnvpdwd@pknnzyakfwxs>
Date: Mon, 13 Oct 2025 14:00:17 +0200
From: Jan Kara <jack@...e.cz>
To: Christoph Hellwig <hch@....de>
Cc: "Matthew Wilcox (Oracle)" <willy@...radead.org>, 
	Eric Van Hensbergen <ericvh@...nel.org>, Latchesar Ionkov <lucho@...kov.net>, 
	Dominique Martinet <asmadeus@...ewreck.org>, Christian Schoenebeck <linux_oss@...debyte.com>, 
	Chris Mason <clm@...com>, David Sterba <dsterba@...e.com>, Mark Fasheh <mark@...heh.com>, 
	Joel Becker <jlbec@...lplan.org>, Joseph Qi <joseph.qi@...ux.alibaba.com>, 
	Alexander Viro <viro@...iv.linux.org.uk>, Christian Brauner <brauner@...nel.org>, 
	Josef Bacik <josef@...icpanda.com>, Jan Kara <jack@...e.cz>, linux-block@...r.kernel.org, 
	v9fs@...ts.linux.dev, linux-btrfs@...r.kernel.org, linux-ext4@...r.kernel.org, 
	linux-fsdevel@...r.kernel.org, jfs-discussion@...ts.sourceforge.net, 
	ocfs2-devel@...ts.linux.dev, linux-xfs@...r.kernel.org, linux-mm@...ck.org
Subject: Re: [PATCH 08/10] mm: remove filemap_fdatawrite_wbc

On Mon 13-10-25 11:58:03, Christoph Hellwig wrote:
> Replace filemap_fdatawrite_wbc, which exposes a writeback_control to the
> callers with a __filemap_fdatawrite helper that takes all the possible
> arguments and declares the writeback_control itself.
> 
> Signed-off-by: Christoph Hellwig <hch@....de>

Looks good. Feel free to add:

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

								Honza

> ---
>  include/linux/pagemap.h |  2 --
>  mm/filemap.c            | 54 ++++++++++++++---------------------------
>  2 files changed, 18 insertions(+), 38 deletions(-)
> 
> diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
> index fc060ce2d31d..742ba1dd3990 100644
> --- a/include/linux/pagemap.h
> +++ b/include/linux/pagemap.h
> @@ -61,8 +61,6 @@ int filemap_fdatawrite_range(struct address_space *mapping,
>  		loff_t start, loff_t end);
>  int filemap_check_errors(struct address_space *mapping);
>  void __filemap_set_wb_err(struct address_space *mapping, int err);
> -int filemap_fdatawrite_wbc(struct address_space *mapping,
> -			   struct writeback_control *wbc);
>  int kiocb_write_and_wait(struct kiocb *iocb, size_t count);
>  
>  static inline int filemap_write_and_wait(struct address_space *mapping)
> diff --git a/mm/filemap.c b/mm/filemap.c
> index bbd5d5eaa661..26b692dbf091 100644
> --- a/mm/filemap.c
> +++ b/mm/filemap.c
> @@ -366,31 +366,30 @@ static int filemap_check_and_keep_errors(struct address_space *mapping)
>  	return 0;
>  }
>  
> -/**
> - * filemap_fdatawrite_wbc - start writeback on mapping dirty pages in range
> - * @mapping:	address space structure to write
> - * @wbc:	the writeback_control controlling the writeout
> - *
> - * Call writepages on the mapping using the provided wbc to control the
> - * writeout.
> - *
> - * Return: %0 on success, negative error code otherwise.
> - */
> -int filemap_fdatawrite_wbc(struct address_space *mapping,
> -			   struct writeback_control *wbc)
> +static int __filemap_fdatawrite(struct address_space *mapping, loff_t start,
> +		loff_t end, enum writeback_sync_modes sync_mode,
> +		long *nr_to_write)
>  {
> +	struct writeback_control wbc = {
> +		.sync_mode	= sync_mode,
> +		.nr_to_write	= nr_to_write ? *nr_to_write : LONG_MAX,
> +		.range_start	= start,
> +		.range_end	= end,
> +	};
>  	int ret;
>  
>  	if (!mapping_can_writeback(mapping) ||
>  	    !mapping_tagged(mapping, PAGECACHE_TAG_DIRTY))
>  		return 0;
>  
> -	wbc_attach_fdatawrite_inode(wbc, mapping->host);
> -	ret = do_writepages(mapping, wbc);
> -	wbc_detach_inode(wbc);
> +	wbc_attach_fdatawrite_inode(&wbc, mapping->host);
> +	ret = do_writepages(mapping, &wbc);
> +	wbc_detach_inode(&wbc);
> +
> +	if (!ret && nr_to_write)
> +		*nr_to_write = wbc.nr_to_write;
>  	return ret;
>  }
> -EXPORT_SYMBOL(filemap_fdatawrite_wbc);
>  
>  /**
>   * __filemap_fdatawrite_range - start writeback on mapping dirty pages in range
> @@ -412,14 +411,7 @@ EXPORT_SYMBOL(filemap_fdatawrite_wbc);
>  int __filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
>  				loff_t end, int sync_mode)
>  {
> -	struct writeback_control wbc = {
> -		.sync_mode = sync_mode,
> -		.nr_to_write = LONG_MAX,
> -		.range_start = start,
> -		.range_end = end,
> -	};
> -
> -	return filemap_fdatawrite_wbc(mapping, &wbc);
> +	return __filemap_fdatawrite(mapping, start, end, sync_mode, NULL);
>  }
>  
>  int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
> @@ -475,18 +467,8 @@ EXPORT_SYMBOL(filemap_flush);
>   */
>  int filemap_fdatawrite_kick_nr(struct address_space *mapping, long *nr_to_write)
>  {
> -	struct writeback_control wbc = {
> -		.nr_to_write = *nr_to_write,
> -		.sync_mode = WB_SYNC_NONE,
> -		.range_start = 0,
> -		.range_end = LLONG_MAX,
> -	};
> -	int ret;
> -
> -	ret = filemap_fdatawrite_wbc(mapping, &wbc);
> -	if (!ret)
> -		*nr_to_write = wbc.nr_to_write;
> -	return ret;
> +	return __filemap_fdatawrite(mapping, 0, LLONG_MAX, WB_SYNC_NONE,
> +			nr_to_write);
>  }
>  EXPORT_SYMBOL_FOR_MODULES(filemap_fdatawrite_kick_nr, "btrfs");
>  
> -- 
> 2.47.3
> 
-- 
Jan Kara <jack@...e.com>
SUSE Labs, CR