[PATCH 3/3] md: Remove the last use of page_buffers()

["Matthew Wilcox (Oracle)" <willy@infradead.org>]

Convert the page to a folio and use folio_buffers() instead.  This
does introduce one extra call to compound_head(), but will simplify a
later conversion of md-bitmap to use folios instead of pages.

Signed-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
---
 drivers/md/md-bitmap.c      | 3 ++-
 include/linux/buffer_head.h | 7 +------
 2 files changed, 3 insertions(+), 7 deletions(-)

diff --git a/drivers/md/md-bitmap.c b/drivers/md/md-bitmap.c
index 7b42db87d536..c2528220c406 100644
--- a/drivers/md/md-bitmap.c
+++ b/drivers/md/md-bitmap.c
@@ -516,7 +516,8 @@ static void end_bitmap_write(struct bio *bio)
 
 static void write_file_page(struct bitmap *bitmap, struct page *page, int wait)
 {
-	struct buffer_head *bh = page_buffers(page);
+	struct folio *folio = page_folio(page);
+	struct buffer_head *bh = folio_buffers(folio);
 
 	while (bh && bh->b_blocknr) {
 		atomic_inc(&bitmap->pending_writes);
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index c9918176adaa..1d5eb6ba4576 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -175,12 +175,7 @@ static inline unsigned long bh_offset(const struct buffer_head *bh)
 	return (unsigned long)(bh)->b_data & (page_size(bh->b_page) - 1);
 }
 
-/* If we *know* page->private refers to buffer_heads */
-#define page_buffers(page)					\
-	({							\
-		BUG_ON(!PagePrivate(page));			\
-		((struct buffer_head *)page_private(page));	\
-	})
+/* If we *know* folio->private refers to buffer_heads */
 #define folio_buffers(folio)		folio_get_private(folio)
 
 void buffer_check_dirty_writeback(struct folio *folio,
-- 
2.47.3