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>

*** 20,29 ****
--- 20,30 ----
   */
  /*
   * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
   * Copyright (c) 2012, 2014 by Delphix. All rights reserved.
   * Copyright (c) 2013 by Saso Kiselkov. All rights reserved.
+  * Copyright (c) 2014 Spectra Logic Corporation, All rights reserved.
   */
  
  #ifndef _SYS_DBUF_H
  #define _SYS_DBUF_H
  
*** 224,236 ****
           */
          avl_node_t db_link;
  
          /* Data which is unique to data (leaf) blocks: */
  
!         /* stuff we store for the user (see dmu_buf_set_user) */
!         void *db_user_ptr;
!         dmu_buf_evict_func_t *db_evict_func;
  
          uint8_t db_immediate_evict;
          uint8_t db_freed_in_flight;
  
          uint8_t db_dirtycnt;
--- 225,236 ----
           */
          avl_node_t db_link;
  
          /* Data which is unique to data (leaf) blocks: */
  
!         /* User callback information. */
!         dmu_buf_user_t *db_user;
  
          uint8_t db_immediate_evict;
          uint8_t db_freed_in_flight;
  
          uint8_t db_dirtycnt;