remove write_cache_pages()

remove write_cache_pages()

[Christoph Hellwig]

Kill of write_cache_pages after converting the last two users to the
iterator.

Diffstat:
 fs/bcachefs/fs-io-buffered.c |   13 ++++++++++++-
 fs/ntfs3/inode.c             |   15 ++++++++++-----
 include/linux/writeback.h    |    6 ------
 mm/page-writeback.c          |   30 ------------------------------
 4 files changed, 22 insertions(+), 42 deletions(-)

[PATCH 1/3] ntfs3: stop using write_cache_pages

[Christoph Hellwig]

Stop using the obsolete write_cache_pages and use writeback_iter directly.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/ntfs3/inode.c | 15 ++++++++++-----
 1 file changed, 10 insertions(+), 5 deletions(-)

diff --git a/fs/ntfs3/inode.c b/fs/ntfs3/inode.c
index 37cbbee7fa58..48b4f73a93ee 100644
--- a/fs/ntfs3/inode.c
+++ b/fs/ntfs3/inode.c
@@ -871,9 +871,9 @@ int ntfs_set_size(struct inode *inode, u64 new_size)
 }
 
 static int ntfs_resident_writepage(struct folio *folio,
-				   struct writeback_control *wbc, void *data)
+				   struct writeback_control *wbc)
 {
-	struct address_space *mapping = data;
+	struct address_space *mapping = folio->mapping;
 	struct inode *inode = mapping->host;
 	struct ntfs_inode *ni = ntfs_i(inode);
 	int ret;
@@ -907,9 +907,14 @@ static int ntfs_writepages(struct address_space *mapping,
 	if (unlikely(ntfs3_forced_shutdown(inode->i_sb)))
 		return -EIO;
 
-	if (is_resident(ntfs_i(inode)))
-		return write_cache_pages(mapping, wbc, ntfs_resident_writepage,
-					 mapping);
+	if (is_resident(ntfs_i(inode))) {
+		struct folio *folio = NULL;
+		int error;
+
+		while ((folio = writeback_iter(mapping, wbc, folio, &error)))
+			error = ntfs_resident_writepage(folio, wbc);
+		return error;
+	}
 	return mpage_writepages(mapping, wbc, ntfs_get_block);
 }
 
-- 
2.47.2

[PATCH 2/3] bcachefs: stop using write_cache_pages

[Christoph Hellwig]

Stop using the obsolete write_cache_pages and use writeback_iter
directly.  This basically just open codes write_cache_pages
without the indirect call, but there's probably ways to structure
the code even nicer as a follow on.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 fs/bcachefs/fs-io-buffered.c | 13 ++++++++++++-
 1 file changed, 12 insertions(+), 1 deletion(-)

diff --git a/fs/bcachefs/fs-io-buffered.c b/fs/bcachefs/fs-io-buffered.c
index 1c54b9b5bd69..fdeaa25189f2 100644
--- a/fs/bcachefs/fs-io-buffered.c
+++ b/fs/bcachefs/fs-io-buffered.c
@@ -655,6 +655,17 @@ static int __bch2_writepage(struct folio *folio,
 	return 0;
 }
 
+static int bch2_write_cache_pages(struct address_space *mapping,
+		      struct writeback_control *wbc, void *data)
+{
+	struct folio *folio = NULL;
+	int error;
+
+	while ((folio = writeback_iter(mapping, wbc, folio, &error)))
+		error = __bch2_writepage(folio, wbc, data);
+	return error;
+}
+
 int bch2_writepages(struct address_space *mapping, struct writeback_control *wbc)
 {
 	struct bch_fs *c = mapping->host->i_sb->s_fs_info;
@@ -663,7 +674,7 @@ int bch2_writepages(struct address_space *mapping, struct writeback_control *wbc
 	bch2_inode_opts_get(&w->opts, c, &to_bch_ei(mapping->host)->ei_inode);
 
 	blk_start_plug(&w->plug);
-	int ret = write_cache_pages(mapping, wbc, __bch2_writepage, w);
+	int ret = bch2_write_cache_pages(mapping, wbc, w);
 	if (w->io)
 		bch2_writepage_do_io(w);
 	blk_finish_plug(&w->plug);
-- 
2.47.2

[PATCH 3/3] mm: remove write_cache_pages

[Christoph Hellwig]

No users left.

Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 include/linux/writeback.h |  6 ------
 mm/page-writeback.c       | 30 ------------------------------
 2 files changed, 36 deletions(-)

diff --git a/include/linux/writeback.h b/include/linux/writeback.h
index a2848d731a46..2a7e134d03ee 100644
--- a/include/linux/writeback.h
+++ b/include/linux/writeback.h
@@ -360,12 +360,6 @@ bool wb_over_bg_thresh(struct bdi_writeback *wb);
 struct folio *writeback_iter(struct address_space *mapping,
 		struct writeback_control *wbc, struct folio *folio, int *error);
 
-typedef int (*writepage_t)(struct folio *folio, struct writeback_control *wbc,
-				void *data);
-
-int write_cache_pages(struct address_space *mapping,
-		      struct writeback_control *wbc, writepage_t writepage,
-		      void *data);
 int do_writepages(struct address_space *mapping, struct writeback_control *wbc);
 void writeback_set_ratelimit(void);
 void tag_pages_for_writeback(struct address_space *mapping,
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 3e248d1c3969..7e1e798e7213 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2590,36 +2590,6 @@ struct folio *writeback_iter(struct address_space *mapping,
 }
 EXPORT_SYMBOL_GPL(writeback_iter);
 
-/**
- * write_cache_pages - walk the list of dirty pages of the given address space and write all of them.
- * @mapping: address space structure to write
- * @wbc: subtract the number of written pages from *@wbc->nr_to_write
- * @writepage: function called for each page
- * @data: data passed to writepage function
- *
- * Return: %0 on success, negative error code otherwise
- *
- * Note: please use writeback_iter() instead.
- */
-int write_cache_pages(struct address_space *mapping,
-		      struct writeback_control *wbc, writepage_t writepage,
-		      void *data)
-{
-	struct folio *folio = NULL;
-	int error;
-
-	while ((folio = writeback_iter(mapping, wbc, folio, &error))) {
-		error = writepage(folio, wbc, data);
-		if (error == AOP_WRITEPAGE_ACTIVATE) {
-			folio_unlock(folio);
-			error = 0;
-		}
-	}
-
-	return error;
-}
-EXPORT_SYMBOL(write_cache_pages);
-
 int do_writepages(struct address_space *mapping, struct writeback_control *wbc)
 {
 	int ret;
-- 
2.47.2

Re: [PATCH 2/3] bcachefs: stop using write_cache_pages

[Kent Overstreet]

On Mon, Aug 18, 2025 at 08:10:09AM +0200, Christoph Hellwig wrote:
> Stop using the obsolete write_cache_pages and use writeback_iter
> directly.  This basically just open codes write_cache_pages
> without the indirect call, but there's probably ways to structure
> the code even nicer as a follow on.

Wouldn't inlining write_cache_pages() achieve the same thing?

> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---
>  fs/bcachefs/fs-io-buffered.c | 13 ++++++++++++-
>  1 file changed, 12 insertions(+), 1 deletion(-)
> 
> diff --git a/fs/bcachefs/fs-io-buffered.c b/fs/bcachefs/fs-io-buffered.c
> index 1c54b9b5bd69..fdeaa25189f2 100644
> --- a/fs/bcachefs/fs-io-buffered.c
> +++ b/fs/bcachefs/fs-io-buffered.c
> @@ -655,6 +655,17 @@ static int __bch2_writepage(struct folio *folio,
>  	return 0;
>  }
>  
> +static int bch2_write_cache_pages(struct address_space *mapping,
> +		      struct writeback_control *wbc, void *data)
> +{
> +	struct folio *folio = NULL;
> +	int error;
> +
> +	while ((folio = writeback_iter(mapping, wbc, folio, &error)))
> +		error = __bch2_writepage(folio, wbc, data);
> +	return error;
> +}
> +
>  int bch2_writepages(struct address_space *mapping, struct writeback_control *wbc)
>  {
>  	struct bch_fs *c = mapping->host->i_sb->s_fs_info;
> @@ -663,7 +674,7 @@ int bch2_writepages(struct address_space *mapping, struct writeback_control *wbc
>  	bch2_inode_opts_get(&w->opts, c, &to_bch_ei(mapping->host)->ei_inode);
>  
>  	blk_start_plug(&w->plug);
> -	int ret = write_cache_pages(mapping, wbc, __bch2_writepage, w);
> +	int ret = bch2_write_cache_pages(mapping, wbc, w);
>  	if (w->io)
>  		bch2_writepage_do_io(w);
>  	blk_finish_plug(&w->plug);
> -- 
> 2.47.2
> 

Re: [PATCH 3/3] mm: remove write_cache_pages

[David Hildenbrand]

On 18.08.25 08:10, Christoph Hellwig wrote:
> No users left.
> 
> Signed-off-by: Christoph Hellwig <hch@lst.de>
> ---

Reviewed-by: David Hildenbrand <david@redhat.com>

-- 
Cheers

David / dhildenb

Re: [PATCH 2/3] bcachefs: stop using write_cache_pages

[Christoph Hellwig]

On Mon, Aug 18, 2025 at 07:17:15AM -0400, Kent Overstreet wrote:
> On Mon, Aug 18, 2025 at 08:10:09AM +0200, Christoph Hellwig wrote:
> > Stop using the obsolete write_cache_pages and use writeback_iter
> > directly.  This basically just open codes write_cache_pages
> > without the indirect call, but there's probably ways to structure
> > the code even nicer as a follow on.
> 
> Wouldn't inlining write_cache_pages() achieve the same thing?

It might eliminate the indirect calls with the right compiler or
options, but not archieve any of the other goals, and leave us
with a helper implementing a pointless callback pattern for 1 user.

> > +
> > +	while ((folio = writeback_iter(mapping, wbc, folio, &error)))
> > +		error = __bch2_writepage(folio, wbc, data);
> > +	return error;
> > +}
> > +
> >  int bch2_writepages(struct address_space *mapping, struct writeback_control *wbc)
> >  {
> >  	struct bch_fs *c = mapping->host->i_sb->s_fs_info;
> > @@ -663,7 +674,7 @@ int bch2_writepages(struct address_space *mapping, struct writeback_control *wbc
> >  	bch2_inode_opts_get(&w->opts, c, &to_bch_ei(mapping->host)->ei_inode);
> >  
> >  	blk_start_plug(&w->plug);
> > -	int ret = write_cache_pages(mapping, wbc, __bch2_writepage, w);
> > +	int ret = bch2_write_cache_pages(mapping, wbc, w);
> >  	if (w->io)
> >  		bch2_writepage_do_io(w);
> >  	blk_finish_plug(&w->plug);
> > -- 
> > 2.47.2
> > 
---end quoted text---