--- a/usr/src/uts/common/fs/zfs/zio.c	Mon May 03 11:16:14 2010 -0700
+++ b/usr/src/uts/common/fs/zfs/zio.c	Mon May 03 14:54:08 2010 -0700
@@ -19,8 +19,7 @@
  * CDDL HEADER END
  */
 /*
- * Copyright 2010 Sun Microsystems, Inc.  All rights reserved.
- * Use is subject to license terms.
+ * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
  */
 
 #include <sys/zfs_context.h>
@@ -661,6 +660,9 @@
 {
 	zio_t *zio;
 
+	dprintf_bp(bp, "freeing in txg %llu, pass %u",
+	    (longlong_t)txg, spa->spa_sync_pass);
+
 	ASSERT(!BP_IS_HOLE(bp));
 	ASSERT(spa_syncing_txg(spa) == txg);
 	ASSERT(spa_sync_pass(spa) <= SYNC_PASS_DEFERRED_FREE);
@@ -2073,6 +2075,8 @@
 	return (ZIO_PIPELINE_CONTINUE);
 }
 
+ddt_entry_t *freedde; /* for debugging */
+
 static int
 zio_ddt_free(zio_t *zio)
 {
@@ -2086,7 +2090,7 @@
 	ASSERT(zio->io_child_type == ZIO_CHILD_LOGICAL);
 
 	ddt_enter(ddt);
-	dde = ddt_lookup(ddt, bp, B_TRUE);
+	freedde = dde = ddt_lookup(ddt, bp, B_TRUE);
 	ddp = ddt_phys_select(dde, bp);
 	ddt_phys_decref(ddp);
 	ddt_exit(ddt);