diff mbox series

[08/12] writeback: Factor writeback_get_folio() out of write_cache_pages()

Message ID 20230626173521.459345-9-willy@infradead.org
State New
Headers
Series Convert write_cache_pages() to an iterator |

Commit Message

Matthew Wilcox June 26, 2023, 5:35 p.m. UTC 
  Move the loop for should-we-write-this-folio to its own function.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 mm/page-writeback.c | 35 +++++++++++++++++++++++------------
 1 file changed, 23 insertions(+), 12 deletions(-)

Comments

Christoph Hellwig June 27, 2023, 4:34 a.m. UTC | #1 
> +	for (;;) {
> +		folio = writeback_get_next(mapping, wbc);
> +		if (!folio)
> +			return NULL;
> +		wbc->done_index = folio->index;
> +
> +		folio_lock(folio);
> +		if (likely(should_writeback_folio(mapping, wbc, folio)))
> +			break;
> +		folio_unlock(folio);
> +	}
> +
> +	trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
> +	return folio;

Same minor nitpick, why not:


	while ((folio = writeback_get_next(mapping, wbc)) {
		wbc->done_index = folio->index;

		folio_lock(folio);
		if (likely(should_writeback_folio(mapping, wbc, folio))) {
			trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
			break;
		}
		folio_unlock(folio);
	}

	return folio;

?
Matthew Wilcox June 27, 2023, 3:25 p.m. UTC | #2 
On Mon, Jun 26, 2023 at 09:34:17PM -0700, Christoph Hellwig wrote:
> > +	for (;;) {
> > +		folio = writeback_get_next(mapping, wbc);
> > +		if (!folio)
> > +			return NULL;
> > +		wbc->done_index = folio->index;
> > +
> > +		folio_lock(folio);
> > +		if (likely(should_writeback_folio(mapping, wbc, folio)))
> > +			break;
> > +		folio_unlock(folio);
> > +	}
> > +
> > +	trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
> > +	return folio;
> 
> Same minor nitpick, why not:
> 
> 
> 	while ((folio = writeback_get_next(mapping, wbc)) {
> 		wbc->done_index = folio->index;
> 
> 		folio_lock(folio);
> 		if (likely(should_writeback_folio(mapping, wbc, folio))) {
> 			trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
> 			break;
> 		}
> 		folio_unlock(folio);
> 	}
> 
> 	return folio;
> 
> ?

Because we end up having to call writeback_finish() somewhere, and it's
neater to do it here than in either writeback_get_next() or both callers
of writeback_get_folio().
diff mbox series

Patch

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 18f332611a52..659df2b5c7c0 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2430,6 +2430,27 @@  static bool should_writeback_folio(struct address_space *mapping,
 	return true;
 }
 
+static struct folio *writeback_get_folio(struct address_space *mapping,
+		struct writeback_control *wbc)
+{
+	struct folio *folio;
+
+	for (;;) {
+		folio = writeback_get_next(mapping, wbc);
+		if (!folio)
+			return NULL;
+		wbc->done_index = folio->index;
+
+		folio_lock(folio);
+		if (likely(should_writeback_folio(mapping, wbc, folio)))
+			break;
+		folio_unlock(folio);
+	}
+
+	trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
+	return folio;
+}
+
 static struct folio *writeback_iter_init(struct address_space *mapping,
 		struct writeback_control *wbc)
 {
@@ -2449,7 +2470,7 @@  static struct folio *writeback_iter_init(struct address_space *mapping,
 	folio_batch_init(&wbc->fbatch);
 	wbc->err = 0;
 
-	return writeback_get_next(mapping, wbc);
+	return writeback_get_folio(mapping, wbc);
 }
 
 /**
@@ -2492,17 +2513,7 @@  int write_cache_pages(struct address_space *mapping,
 
 	for (folio = writeback_iter_init(mapping, wbc);
 	     folio;
-	     folio = writeback_get_next(mapping, wbc)) {
-		wbc->done_index = folio->index;
-
-		folio_lock(folio);
-		if (!should_writeback_folio(mapping, wbc, folio)) {
-			folio_unlock(folio);
-			continue;
-		}
-
-		trace_wbc_writepage(wbc, inode_to_bdi(mapping->host));
-
+	     folio = writeback_get_folio(mapping, wbc)) {
 		error = writepage(folio, wbc, data);
 		if (unlikely(error)) {
 			/*