5056 ZFS deadlock on db_mtx and dn_holds
Reviewed by: Will Andrews <willa@spectralogic.com>
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <george.wilson@delphix.com>
Approved by: Dan McDonald <danmcd@omniti.com>

@@ -19,10 +19,11 @@
  * CDDL HEADER END
  */
 /*
  * Copyright (c) 2010, Oracle and/or its affiliates. All rights reserved.
  * Copyright (c) 2012 by Delphix. All rights reserved.
+ * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
  */
 
 #include <sys/dsl_dataset.h>
 #include <sys/dmu.h>
 #include <sys/refcount.h>

@@ -117,10 +118,12 @@
 dsl_deadlist_close(dsl_deadlist_t *dl)
 {
         void *cookie = NULL;
         dsl_deadlist_entry_t *dle;
 
+        dl->dl_os = NULL;
+
         if (dl->dl_oldfmt) {
                 dl->dl_oldfmt = B_FALSE;
                 bpobj_close(&dl->dl_bpobj);
                 return;
         }