diff --git a/fs/btrfs/extent_map.h b/fs/btrfs/extent_map.h
index accfeda..fb6eeef 100644
--- a/fs/btrfs/extent_map.h
+++ b/fs/btrfs/extent_map.h
@@ -20,6 +20,7 @@
 	/* all of these are in bytes */
 	u64 start;
 	u64 len;
+	u64 orig_start;
 	u64 block_start;
 	u64 block_len;
 	unsigned long flags;