[RFC PATCH v1 01/10] mm: pass number of pages to __folio_start_writeback()

[Joanne Koong <joannelkoong@xxxxxxxxx>]

Add an additional arg to __folio_start_writeback() that takes in the
number of pages to write back.

Signed-off-by: Joanne Koong <joannelkoong@xxxxxxxxx>
---
 fs/ext4/page-io.c          |  2 +-
 include/linux/page-flags.h |  6 +++---
 mm/page-writeback.c        | 10 +++++-----
 3 files changed, 9 insertions(+), 9 deletions(-)

diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c
index 179e54f3a3b6..b9ee40872040 100644
--- a/fs/ext4/page-io.c
+++ b/fs/ext4/page-io.c
@@ -580,7 +580,7 @@ int ext4_bio_write_folio(struct ext4_io_submit *io, struct folio *folio,
 		io_folio = page_folio(bounce_page);
 	}
 
-	__folio_start_writeback(folio, keep_towrite);
+	__folio_start_writeback(folio, keep_towrite, folio_nr_pages(folio));
 
 	/* Now submit buffers to write */
 	do {
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 4fe5ee67535b..7ec85ece9b67 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -854,13 +854,13 @@ static __always_inline void SetPageUptodate(struct page *page)
 
 CLEARPAGEFLAG(Uptodate, uptodate, PF_NO_TAIL)
 
-void __folio_start_writeback(struct folio *folio, bool keep_write);
+void __folio_start_writeback(struct folio *folio, bool keep_write, long nr_pages);
 void set_page_writeback(struct page *page);
 
 #define folio_start_writeback(folio)			\
-	__folio_start_writeback(folio, false)
+	__folio_start_writeback(folio, false, folio_nr_pages(folio))
 #define folio_start_writeback_keepwrite(folio)	\
-	__folio_start_writeback(folio, true)
+	__folio_start_writeback(folio, true, folio_nr_pages(folio))
 
 static __always_inline bool folio_test_head(const struct folio *folio)
 {
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 11f9a909e8de..2e6b132f7ac2 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -3044,9 +3044,9 @@ bool __folio_end_writeback(struct folio *folio)
 	return ret;
 }
 
-void __folio_start_writeback(struct folio *folio, bool keep_write)
+void __folio_start_writeback(struct folio *folio, bool keep_write,
+		long nr_pages)
 {
-	long nr = folio_nr_pages(folio);
 	struct address_space *mapping = folio_mapping(folio);
 	int access_ret;
 
@@ -3067,7 +3067,7 @@ void __folio_start_writeback(struct folio *folio, bool keep_write)
 		on_wblist = mapping_tagged(mapping, PAGECACHE_TAG_WRITEBACK);
 
 		xas_set_mark(&xas, PAGECACHE_TAG_WRITEBACK);
-		wb_stat_mod(wb, WB_WRITEBACK, nr);
+		wb_stat_mod(wb, WB_WRITEBACK, nr_pages);
 		if (!on_wblist) {
 			wb_inode_writeback_start(wb);
 			/*
@@ -3088,8 +3088,8 @@ void __folio_start_writeback(struct folio *folio, bool keep_write)
 		folio_test_set_writeback(folio);
 	}
 
-	lruvec_stat_mod_folio(folio, NR_WRITEBACK, nr);
-	zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, nr);
+	lruvec_stat_mod_folio(folio, NR_WRITEBACK, nr_pages);
+	zone_stat_mod_folio(folio, NR_ZONE_WRITE_PENDING, nr_pages);
 
 	access_ret = arch_make_folio_accessible(folio);
 	/*
-- 
2.47.3