nilfs2: convert nilfs_btnode_create_block to use a folio

Saves two calls to compound_head().

Link: https://lkml.kernel.org/r/20231114084436.2755-16-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/btnode.c

@@ -64,8 +64,8 @@ nilfs_btnode_create_block(struct address_space *btnc, __u64 blocknr)
 	set_buffer_mapped(bh);
 	set_buffer_uptodate(bh);
 
-	unlock_page(bh->b_page);
-	put_page(bh->b_page);
+	folio_unlock(bh->b_folio);
+	folio_put(bh->b_folio);
 	return bh;
 }