diff mbox series

[03/11] writeback: Factor should_writeback_folio() out of write_cache_pages()

Message ID 20231214132544.376574-4-hch@lst.de
State New
Headers
Series [01/11] writeback: Factor out writeback_finish() |

Commit Message

Christoph Hellwig Dec. 14, 2023, 1:25 p.m. UTC 
  From: "Matthew Wilcox (Oracle)" <willy@infradead.org>

Reduce write_cache_pages() by about 30 lines; much of it is commentary,
but it all bundles nicely into an obvious function.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Christoph Hellwig <hch@lst.de>
---
 mm/page-writeback.c | 59 ++++++++++++++++++++++++---------------------
 1 file changed, 32 insertions(+), 27 deletions(-)

Comments

Jan Kara Dec. 15, 2023, 2:16 p.m. UTC | #1 
On Thu 14-12-23 14:25:36, Christoph Hellwig wrote:
> From: "Matthew Wilcox (Oracle)" <willy@infradead.org>
> 
> Reduce write_cache_pages() by about 30 lines; much of it is commentary,
> but it all bundles nicely into an obvious function.
> 
> Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
> Signed-off-by: Christoph Hellwig <hch@lst.de>

I like this! Feel free to add:

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

								Honza

> ---
>  mm/page-writeback.c | 59 ++++++++++++++++++++++++---------------------
>  1 file changed, 32 insertions(+), 27 deletions(-)
> 
> diff --git a/mm/page-writeback.c b/mm/page-writeback.c
> index 5d33e7b468e2cc..5a3df8665ff4f9 100644
> --- a/mm/page-writeback.c
> +++ b/mm/page-writeback.c
> @@ -2394,6 +2394,36 @@ static void writeback_get_batch(struct address_space *mapping,
>  			&wbc->fbatch);
>  }
>  
> +static bool should_writeback_folio(struct address_space *mapping,
> +		struct writeback_control *wbc, struct folio *folio)
> +{
> +	/*
> +	 * Folio truncated or invalidated. We can freely skip it then,
> +	 * even for data integrity operations: the folio has disappeared
> +	 * concurrently, so there could be no real expectation of this
> +	 * data integrity operation even if there is now a new, dirty
> +	 * folio at the same pagecache index.
> +	 */
> +	if (unlikely(folio->mapping != mapping))
> +		return false;
> +
> +	/* Did somebody write it for us? */
> +	if (!folio_test_dirty(folio))
> +		return false;
> +
> +	if (folio_test_writeback(folio)) {
> +		if (wbc->sync_mode == WB_SYNC_NONE)
> +			return false;
> +		folio_wait_writeback(folio);
> +	}
> +
> +	BUG_ON(folio_test_writeback(folio));
> +	if (!folio_clear_dirty_for_io(folio))
> +		return false;
> +
> +	return true;
> +}
> +
>  /**
>   * 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
> @@ -2462,38 +2492,13 @@ int write_cache_pages(struct address_space *mapping,
>  			wbc->done_index = folio->index;
>  
>  			folio_lock(folio);
> -
> -			/*
> -			 * Page truncated or invalidated. We can freely skip it
> -			 * then, even for data integrity operations: the page
> -			 * has disappeared concurrently, so there could be no
> -			 * real expectation of this data integrity operation
> -			 * even if there is now a new, dirty page at the same
> -			 * pagecache address.
> -			 */
> -			if (unlikely(folio->mapping != mapping)) {
> -continue_unlock:
> +			if (!should_writeback_folio(mapping, wbc, folio)) {
>  				folio_unlock(folio);
>  				continue;
>  			}
>  
> -			if (!folio_test_dirty(folio)) {
> -				/* someone wrote it for us */
> -				goto continue_unlock;
> -			}
> -
> -			if (folio_test_writeback(folio)) {
> -				if (wbc->sync_mode != WB_SYNC_NONE)
> -					folio_wait_writeback(folio);
> -				else
> -					goto continue_unlock;
> -			}
> -
> -			BUG_ON(folio_test_writeback(folio));
> -			if (!folio_clear_dirty_for_io(folio))
> -				goto continue_unlock;
> -
>  			trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
> +
>  			error = writepage(folio, wbc, data);
>  			nr = folio_nr_pages(folio);
>  			if (unlikely(error)) {
> -- 
> 2.39.2
>
diff mbox series

Patch

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 5d33e7b468e2cc..5a3df8665ff4f9 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2394,6 +2394,36 @@  static void writeback_get_batch(struct address_space *mapping,
 			&wbc->fbatch);
 }
 
+static bool should_writeback_folio(struct address_space *mapping,
+		struct writeback_control *wbc, struct folio *folio)
+{
+	/*
+	 * Folio truncated or invalidated. We can freely skip it then,
+	 * even for data integrity operations: the folio has disappeared
+	 * concurrently, so there could be no real expectation of this
+	 * data integrity operation even if there is now a new, dirty
+	 * folio at the same pagecache index.
+	 */
+	if (unlikely(folio->mapping != mapping))
+		return false;
+
+	/* Did somebody write it for us? */
+	if (!folio_test_dirty(folio))
+		return false;
+
+	if (folio_test_writeback(folio)) {
+		if (wbc->sync_mode == WB_SYNC_NONE)
+			return false;
+		folio_wait_writeback(folio);
+	}
+
+	BUG_ON(folio_test_writeback(folio));
+	if (!folio_clear_dirty_for_io(folio))
+		return false;
+
+	return true;
+}
+
 /**
  * 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
@@ -2462,38 +2492,13 @@  int write_cache_pages(struct address_space *mapping,
 			wbc->done_index = folio->index;
 
 			folio_lock(folio);
-
-			/*
-			 * Page truncated or invalidated. We can freely skip it
-			 * then, even for data integrity operations: the page
-			 * has disappeared concurrently, so there could be no
-			 * real expectation of this data integrity operation
-			 * even if there is now a new, dirty page at the same
-			 * pagecache address.
-			 */
-			if (unlikely(folio->mapping != mapping)) {
-continue_unlock:
+			if (!should_writeback_folio(mapping, wbc, folio)) {
 				folio_unlock(folio);
 				continue;
 			}
 
-			if (!folio_test_dirty(folio)) {
-				/* someone wrote it for us */
-				goto continue_unlock;
-			}
-
-			if (folio_test_writeback(folio)) {
-				if (wbc->sync_mode != WB_SYNC_NONE)
-					folio_wait_writeback(folio);
-				else
-					goto continue_unlock;
-			}
-
-			BUG_ON(folio_test_writeback(folio));
-			if (!folio_clear_dirty_for_io(folio))
-				goto continue_unlock;
-
 			trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
+
 			error = writepage(folio, wbc, data);
 			nr = folio_nr_pages(folio);
 			if (unlikely(error)) {