[PATCH 14/14] writeback: Remove a use of write_cache_pages() from do_writepages()

[Christoph Hellwig]

From: "Matthew Wilcox (Oracle)" <willy@xxxxxxxxxxxxx>

Use the new writeback_iter() directly instead of indirecting
through a callback.

Signed-off-by: Matthew Wilcox (Oracle) <willy@xxxxxxxxxxxxx>
[hch: ported to the while based iter style]
Signed-off-by: Christoph Hellwig <hch@xxxxxx>
Reviewed-by: Brian Foster <bfoster@xxxxxxxxxx>
Reviewed-by: Jan Kara <jack@xxxxxxx>
---
 mm/page-writeback.c | 31 ++++++++++++++++++-------------
 1 file changed, 18 insertions(+), 13 deletions(-)

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 3da4345f08a335..3e19b87049db17 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2577,15 +2577,25 @@ int write_cache_pages(struct address_space *mapping,
 }
 EXPORT_SYMBOL(write_cache_pages);
 
-static int writepage_cb(struct folio *folio, struct writeback_control *wbc,
-		void *data)
+static int writeback_use_writepage(struct address_space *mapping,
+		struct writeback_control *wbc)
 {
-	struct address_space *mapping = data;
-	int ret = mapping->a_ops->writepage(&folio->page, wbc);
+	struct folio *folio = NULL;
+	struct blk_plug plug;
+	int err;
 
-	if (ret < 0)
-		mapping_set_error(mapping, ret);
-	return ret;
+	blk_start_plug(&plug);
+	while ((folio = writeback_iter(mapping, wbc, folio, &err))) {
+		err = mapping->a_ops->writepage(&folio->page, wbc);
+		if (err == AOP_WRITEPAGE_ACTIVATE) {
+			folio_unlock(folio);
+			err = 0;
+		}
+		mapping_set_error(mapping, err);
+	}
+	blk_finish_plug(&plug);
+
+	return err;
 }
 
 int do_writepages(struct address_space *mapping, struct writeback_control *wbc)
@@ -2601,12 +2611,7 @@ int do_writepages(struct address_space *mapping, struct writeback_control *wbc)
 		if (mapping->a_ops->writepages) {
 			ret = mapping->a_ops->writepages(mapping, wbc);
 		} else if (mapping->a_ops->writepage) {
-			struct blk_plug plug;
-
-			blk_start_plug(&plug);
-			ret = write_cache_pages(mapping, wbc, writepage_cb,
-						mapping);
-			blk_finish_plug(&plug);
+			ret = writeback_use_writepage(mapping, wbc);
 		} else {
 			/* deal with chardevs and other special files */
 			ret = 0;
-- 
2.39.2