diff --git a/include/linux/jbd2.h b/include/linux/jbd2.h
index 27e79c27ba08..a32dcaec04e1 100644
--- a/include/linux/jbd2.h
+++ b/include/linux/jbd2.h
@@ -432,13 +432,35 @@ struct jbd2_journal_handle
 	int			h_err;
 
 	/* Flags [no locking] */
-	unsigned int	h_sync:		1;	/* sync-on-close */
-	unsigned int	h_jdata:	1;	/* force data journaling */
-	unsigned int	h_aborted:	1;	/* fatal error on handle */
+	unsigned int	h_sync:1;	/* sync-on-close */
+	unsigned int	h_jdata:1;	/* force data journaling */
+	unsigned int	h_aborted:1;	/* fatal error on handle */
+	unsigned int	h_cowing:1;	/* COWing block to snapshot */
+
+	/* Number of buffers requested by user:
+	 * (before adding the COW credits factor) */
+	unsigned int	h_base_credits:14;
+
+	/* Number of buffers the user is allowed to dirty:
+	 * (counts only buffers dirtied when !h_cowing) */
+	unsigned int	h_user_credits:14;
+
 
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 	struct lockdep_map	h_lockdep_map;
 #endif
+
+#ifdef CONFIG_JBD2_DEBUG
+	/* COW debugging counters: */
+	unsigned int h_cow_moved; /* blocks moved to snapshot */
+	unsigned int h_cow_copied; /* blocks copied to snapshot */
+	unsigned int h_cow_ok_jh; /* blocks already COWed during current
+				     transaction */
+	unsigned int h_cow_ok_bitmap; /* blocks not set in COW bitmap */
+	unsigned int h_cow_ok_mapped;/* blocks already mapped in snapshot */
+	unsigned int h_cow_bitmaps; /* COW bitmaps created */
+	unsigned int h_cow_excluded; /* blocks set in exclude bitmap */
+#endif
 };