Re: [PATCH 2/3] writeback: allow the file system to override MIN_WRITEBACK_PAGES

[Damien Le Moal <dlemoal@kernel.org>]

On 2025/10/15 15:27, Christoph Hellwig wrote:
> The relatively low minimal writeback size of 4MiB leads means that

Removes "leads" in the above.

> written back inodes on rotational media are switched a lot.  Besides
> introducing additional seeks, this also can lead to extreme file
> fragmentation on zoned devices when a lot of files are cached relative
> to the available writeback bandwidth.
> 
> Add a superblock field that allows the file system to override the
> default size.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>

> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index c895146c1444..23f1f10646b7 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -1583,6 +1583,7 @@ struct super_block {
>  
>  	spinlock_t		s_inode_wblist_lock;
>  	struct list_head	s_inodes_wb;	/* writeback inodes */
> +	unsigned int		s_min_writeback_pages;

Given that writeback_chunk_size() returns a long type, maybe this should be a long ?

>  } __randomize_layout;
>  
>  static inline struct user_namespace *i_user_ns(const struct inode *inode)



-- 
Damien Le Moal
Western Digital Research