Re: [PATCH 05/12] iomap: add public helpers for uptodate state manipulation

[Brian Foster <bfoster@redhat.com>]

On Fri, Jun 27, 2025 at 09:02:38AM +0200, Christoph Hellwig wrote:
> From: Joanne Koong <joannelkoong@gmail.com>
> 
> Add a new iomap_start_folio_write helper to abstract away the
> write_bytes_pending handling, and export it and the existing
> iomap_finish_folio_write for non-iomap writeback in fuse.
> 
> Signed-off-by: Joanne Koong <joannelkoong@gmail.com>
> [hch: split from a larger patch]
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

Reviewed-by: Brian Foster <bfoster@redhat.com>

>  fs/iomap/buffered-io.c | 20 +++++++++++++++-----
>  include/linux/iomap.h  |  5 +++++
>  2 files changed, 20 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/iomap/buffered-io.c b/fs/iomap/buffered-io.c
> index a72ab487c8ab..d152456d41a8 100644
> --- a/fs/iomap/buffered-io.c
> +++ b/fs/iomap/buffered-io.c
> @@ -1535,7 +1535,18 @@ vm_fault_t iomap_page_mkwrite(struct vm_fault *vmf, const struct iomap_ops *ops,
>  }
>  EXPORT_SYMBOL_GPL(iomap_page_mkwrite);
>  
> -static void iomap_finish_folio_write(struct inode *inode, struct folio *folio,
> +void iomap_start_folio_write(struct inode *inode, struct folio *folio,
> +		size_t len)
> +{
> +	struct iomap_folio_state *ifs = folio->private;
> +
> +	WARN_ON_ONCE(i_blocks_per_folio(inode, folio) > 1 && !ifs);
> +	if (ifs)
> +		atomic_add(len, &ifs->write_bytes_pending);
> +}
> +EXPORT_SYMBOL_GPL(iomap_start_folio_write);
> +
> +void iomap_finish_folio_write(struct inode *inode, struct folio *folio,
>  		size_t len)
>  {
>  	struct iomap_folio_state *ifs = folio->private;
> @@ -1546,6 +1557,7 @@ static void iomap_finish_folio_write(struct inode *inode, struct folio *folio,
>  	if (!ifs || atomic_sub_and_test(len, &ifs->write_bytes_pending))
>  		folio_end_writeback(folio);
>  }
> +EXPORT_SYMBOL_GPL(iomap_finish_folio_write);
>  
>  /*
>   * We're now finished for good with this ioend structure.  Update the page
> @@ -1668,7 +1680,6 @@ ssize_t iomap_add_to_ioend(struct iomap_writeback_ctx *wpc, struct folio *folio,
>  		loff_t pos, loff_t end_pos, unsigned int dirty_len)
>  {
>  	struct iomap_ioend *ioend = wpc->wb_ctx;
> -	struct iomap_folio_state *ifs = folio->private;
>  	size_t poff = offset_in_folio(folio, pos);
>  	unsigned int ioend_flags = 0;
>  	unsigned int map_len = min_t(u64, dirty_len,
> @@ -1711,8 +1722,7 @@ ssize_t iomap_add_to_ioend(struct iomap_writeback_ctx *wpc, struct folio *folio,
>  	if (!bio_add_folio(&ioend->io_bio, folio, map_len, poff))
>  		goto new_ioend;
>  
> -	if (ifs)
> -		atomic_add(map_len, &ifs->write_bytes_pending);
> +	iomap_start_folio_write(wpc->inode, folio, map_len);
>  
>  	/*
>  	 * Clamp io_offset and io_size to the incore EOF so that ondisk
> @@ -1880,7 +1890,7 @@ static int iomap_writepage_map(struct iomap_writeback_ctx *wpc,
>  		 * all blocks.
>  		 */
>  		WARN_ON_ONCE(atomic_read(&ifs->write_bytes_pending) != 0);
> -		atomic_inc(&ifs->write_bytes_pending);
> +		iomap_start_folio_write(inode, folio, 1);
>  	}
>  
>  	/*
> diff --git a/include/linux/iomap.h b/include/linux/iomap.h
> index b65951cdb0b5..1a07d8fa9459 100644
> --- a/include/linux/iomap.h
> +++ b/include/linux/iomap.h
> @@ -460,6 +460,11 @@ void iomap_sort_ioends(struct list_head *ioend_list);
>  ssize_t iomap_add_to_ioend(struct iomap_writeback_ctx *wpc, struct folio *folio,
>  		loff_t pos, loff_t end_pos, unsigned int dirty_len);
>  int ioend_writeback_submit(struct iomap_writeback_ctx *wpc, int error);
> +
> +void iomap_start_folio_write(struct inode *inode, struct folio *folio,
> +		size_t len);
> +void iomap_finish_folio_write(struct inode *inode, struct folio *folio,
> +		size_t len);
>  int iomap_writepages(struct iomap_writeback_ctx *wpc);
>  
>  /*
> -- 
> 2.47.2
> 
>