Illumos #2619 and #2747

2619 asynchronous destruction of ZFS file systems
2747 SPA versioning with zfs feature flags
Reviewed by: Matt Ahrens <mahrens@delphix.com>
Reviewed by: George Wilson <gwilson@delphix.com>
Reviewed by: Richard Lowe <richlowe@richlowe.net>
Reviewed by: Dan Kruchinin <dan.kruchinin@gmail.com>
Approved by: Eric Schrock <Eric.Schrock@delphix.com>

References:
  illumos/illumos-gate@53089ab7c8
  illumos/illumos-gate@ad135b5d64
  illumos changeset: 13700:2889e2596bd6
  https://www.illumos.org/issues/2619
  https://www.illumos.org/issues/2747

NOTE: The grub specific changes were not ported.  This change
must be made to the Linux grub packages.

Ported-by: Brian Behlendorf <behlendorf1@llnl.gov>

include/sys/zap.h

@@ -20,6 +20,7 @@
  */
 /*
  * Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
+ * Copyright (c) 2012 by Delphix. All rights reserved.
  */
 
 #ifndef	_SYS_ZAP_H
@@ -132,6 +133,8 @@ uint64_t zap_create_norm(objset_t *ds, int normflags, dmu_object_type_t ot,
 uint64_t zap_create_flags(objset_t *os, int normflags, zap_flags_t flags,
     dmu_object_type_t ot, int leaf_blockshift, int indirect_blockshift,
     dmu_object_type_t bonustype, int bonuslen, dmu_tx_t *tx);
+uint64_t zap_create_link(objset_t *os, dmu_object_type_t ot,
+    uint64_t parent_obj, const char *name, dmu_tx_t *tx);
 
 /*
  * Create a new zapobj with no attributes from the given (unallocated)
@@ -300,10 +303,6 @@ int zap_add_int_key(objset_t *os, uint64_t obj,
 int zap_lookup_int_key(objset_t *os, uint64_t obj,
     uint64_t key, uint64_t *valuep);
 
-/*
- * They name is a stringified version of key; increment its value by
- * delta.  Zero values will be zap_remove()-ed.
- */
 int zap_increment(objset_t *os, uint64_t obj, const char *name, int64_t delta,
     dmu_tx_t *tx);