3740 Poor ZFS send / receive performance due to snapshot hold / release processing
Submitted by: Steven Hartland <steven.hartland@multiplay.co.uk>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>

*** 22,31 ****
--- 22,32 ----
  /*
   * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
   * Copyright 2011 Nexenta Systems, Inc. All rights reserved.
   * Copyright (c) 2012 by Delphix. All rights reserved.
   * Copyright (c) 2012, Joyent, Inc. All rights reserved.
+  * Copyright (c) 2013 Steven Hartland. All rights reserved.
   */
  
  #ifndef _LIBZFS_H
  #define _LIBZFS_H
  
*** 592,602 ****
  extern int zfs_send(zfs_handle_t *, const char *, const char *,
      sendflags_t *, int, snapfilter_cb_t, void *, nvlist_t **);
  
  extern int zfs_promote(zfs_handle_t *);
  extern int zfs_hold(zfs_handle_t *, const char *, const char *,
!     boolean_t, boolean_t, int);
  extern int zfs_release(zfs_handle_t *, const char *, const char *, boolean_t);
  extern int zfs_get_holds(zfs_handle_t *, nvlist_t **);
  extern uint64_t zvol_volsize_to_reservation(uint64_t, nvlist_t *);
  
  typedef int (*zfs_userspace_cb_t)(void *arg, const char *domain,
--- 593,604 ----
  extern int zfs_send(zfs_handle_t *, const char *, const char *,
      sendflags_t *, int, snapfilter_cb_t, void *, nvlist_t **);
  
  extern int zfs_promote(zfs_handle_t *);
  extern int zfs_hold(zfs_handle_t *, const char *, const char *,
!     boolean_t, int);
! extern int zfs_hold_nvl(zfs_handle_t *, int, nvlist_t *);
  extern int zfs_release(zfs_handle_t *, const char *, const char *, boolean_t);
  extern int zfs_get_holds(zfs_handle_t *, nvlist_t **);
  extern uint64_t zvol_volsize_to_reservation(uint64_t, nvlist_t *);
  
  typedef int (*zfs_userspace_cb_t)(void *arg, const char *domain,