Btrfs: Make the resizer work based on shrinking and growing devices

Signed-off-by: Chris Mason <chris.mason@oracle.com>
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index f00c4be..ac7106e 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -474,6 +474,7 @@
 	u64 pinned;
 	u64 flags;
 	int cached;
+	int ro;
 };
 
 struct btrfs_device;