3756 want lz4 support for metadata compression

*** 20,29 ****
--- 20,30 ----
   */
  /*
   * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
   * Copyright 2011 Nexenta Systems, Inc.  All rights reserved.
   * Copyright (c) 2013 by Delphix. All rights reserved.
+  * Copyright (c) 2013 Martin Matuska. All rights reserved.
   */
  
  #include <sys/zfs_context.h>
  #include <sys/dmu.h>
  #include <sys/dmu_impl.h>
*** 2680,2690 ****
  
          if (db->db_blkid == DMU_SPILL_BLKID)
                  wp_flag = WP_SPILL;
          wp_flag |= (db->db_state == DB_NOFILL) ? WP_NOFILL : 0;
  
!         dmu_write_policy(os, dn, db->db_level, wp_flag, &zp);
          DB_DNODE_EXIT(db);
  
          if (db->db_level == 0 && dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
                  ASSERT(db->db_state != DB_NOFILL);
                  dr->dr_zio = zio_write(zio, os->os_spa, txg,
--- 2681,2691 ----
  
          if (db->db_blkid == DMU_SPILL_BLKID)
                  wp_flag = WP_SPILL;
          wp_flag |= (db->db_state == DB_NOFILL) ? WP_NOFILL : 0;
  
!         dmu_write_policy(os, dn, db->db_level, wp_flag, &zp, txg);
          DB_DNODE_EXIT(db);
  
          if (db->db_level == 0 && dr->dt.dl.dr_override_state == DR_OVERRIDDEN) {
                  ASSERT(db->db_state != DB_NOFILL);
                  dr->dr_zio = zio_write(zio, os->os_spa, txg,