nilfs2: convert nilfs_forget_buffer to use a folio

Save two hidden calls to compound_head().

Link: https://lkml.kernel.org/r/20231114084436.2755-5-konishi.ryusuke@gmail.comSigned-off-by: Matthew Wilcox (Oracle) <willy@infradead.org>
Signed-off-by: Ryusuke Konishi <konishi.ryusuke@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

fs/nilfs2/page.c

@@ -73,7 +73,7 @@ struct buffer_head *nilfs_grab_buffer(struct inode *inode,
  */
 void nilfs_forget_buffer(struct buffer_head *bh)
 {
-	struct page *page = bh->b_page;
+	struct folio *folio = bh->b_folio;
 	const unsigned long clear_bits =
 		(BIT(BH_Uptodate) | BIT(BH_Dirty) | BIT(BH_Mapped) |
 		 BIT(BH_Async_Write) | BIT(BH_NILFS_Volatile) |
@@ -81,12 +81,12 @@ void nilfs_forget_buffer(struct buffer_head *bh)
 
 	lock_buffer(bh);
 	set_mask_bits(&bh->b_state, clear_bits, 0);
-	if (nilfs_page_buffers_clean(page))
-		__nilfs_clear_page_dirty(page);
+	if (nilfs_page_buffers_clean(&folio->page))
+		__nilfs_clear_page_dirty(&folio->page);
 
 	bh->b_blocknr = -1;
-	ClearPageUptodate(page);
-	ClearPageMappedToDisk(page);
+	folio_clear_uptodate(folio);
+	folio_clear_mappedtodisk(folio);
 	unlock_buffer(bh);
 	brelse(bh);
 }