[PATCH 3/4] fs/buffer: add folio_create_empty_buffers helper

[Pankaj Raghav]

Folio version of create_empty_buffers(). This is required to convert
create_page_buffers() to folio_create_buffers() later in the series.

It removes several calls to compound_head() as it works directly on folio
compared to create_empty_buffers(). Hence, create_empty_buffers() has
been modified to call folio_create_empty_buffers().

Signed-off-by: Pankaj Raghav <p.raghav@xxxxxxxxxxx>
---
 fs/buffer.c                 | 28 +++++++++++++++++-----------
 include/linux/buffer_head.h |  2 ++
 2 files changed, 19 insertions(+), 11 deletions(-)

diff --git a/fs/buffer.c b/fs/buffer.c
index 75415170e286..13724ef7eec7 100644
--- a/fs/buffer.c
+++ b/fs/buffer.c
@@ -1593,18 +1593,17 @@ void block_invalidate_folio(struct folio *folio, size_t offset, size_t length)
 }
 EXPORT_SYMBOL(block_invalidate_folio);
 
-
 /*
  * We attach and possibly dirty the buffers atomically wrt
  * block_dirty_folio() via private_lock.  try_to_free_buffers
- * is already excluded via the page lock.
+ * is already excluded via the folio lock.
  */
-void create_empty_buffers(struct page *page,
-			unsigned long blocksize, unsigned long b_state)
+void folio_create_empty_buffers(struct folio *folio, unsigned long blocksize,
+				unsigned long b_state)
 {
 	struct buffer_head *bh, *head, *tail;
 
-	head = alloc_page_buffers(page, blocksize, true);
+	head = folio_alloc_buffers(folio, blocksize, true);
 	bh = head;
 	do {
 		bh->b_state |= b_state;
@@ -1613,19 +1612,26 @@ void create_empty_buffers(struct page *page,
 	} while (bh);
 	tail->b_this_page = head;
 
-	spin_lock(&page->mapping->private_lock);
-	if (PageUptodate(page) || PageDirty(page)) {
+	spin_lock(&folio->mapping->private_lock);
+	if (folio_test_uptodate(folio) || folio_test_dirty(folio)) {
 		bh = head;
 		do {
-			if (PageDirty(page))
+			if (folio_test_dirty(folio))
 				set_buffer_dirty(bh);
-			if (PageUptodate(page))
+			if (folio_test_uptodate(folio))
 				set_buffer_uptodate(bh);
 			bh = bh->b_this_page;
 		} while (bh != head);
 	}
-	attach_page_private(page, head);
-	spin_unlock(&page->mapping->private_lock);
+	folio_attach_private(folio, head);
+	spin_unlock(&folio->mapping->private_lock);
+}
+EXPORT_SYMBOL(folio_create_empty_buffers);
+
+void create_empty_buffers(struct page *page,
+			unsigned long blocksize, unsigned long b_state)
+{
+	folio_create_empty_buffers(page_folio(page), blocksize, b_state);
 }
 EXPORT_SYMBOL(create_empty_buffers);
 
diff --git a/include/linux/buffer_head.h b/include/linux/buffer_head.h
index 0b14eab41bd1..1520793c72da 100644
--- a/include/linux/buffer_head.h
+++ b/include/linux/buffer_head.h
@@ -205,6 +205,8 @@ struct buffer_head *alloc_page_buffers(struct page *page, unsigned long size,
 		bool retry);
 void create_empty_buffers(struct page *, unsigned long,
 			unsigned long b_state);
+void folio_create_empty_buffers(struct folio *folio, unsigned long blocksize,
+				unsigned long b_state);
 void end_buffer_read_sync(struct buffer_head *bh, int uptodate);
 void end_buffer_write_sync(struct buffer_head *bh, int uptodate);
 void end_buffer_async_write(struct buffer_head *bh, int uptodate);
-- 
2.34.1