diff --git a/cmd/ztest/ztest.c b/cmd/ztest/ztest.c
index 0a3653f7ff..31205a5bf8 100644
--- a/cmd/ztest/ztest.c
+++ b/cmd/ztest/ztest.c
@@ -116,7 +116,7 @@
 #include <sys/dsl_destroy.h>
 #include <sys/dsl_scan.h>
 #include <sys/zio_checksum.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #include <sys/zfeature.h>
 #include <sys/dsl_userhold.h>
 #include <sys/abd.h>
diff --git a/include/os/freebsd/spl/sys/ccompile.h b/include/os/freebsd/spl/sys/ccompile.h
index cfb94268bf..c594c928f8 100644
--- a/include/os/freebsd/spl/sys/ccompile.h
+++ b/include/os/freebsd/spl/sys/ccompile.h
@@ -119,7 +119,7 @@ extern "C" {
 #define	__CONST			__sun_attr__((__const__))
 #define	__PURE			__sun_attr__((__pure__))
 
-#ifdef INVARIANTS
+#if defined(INVARIANTS) && !defined(ZFS_DEBUG)
 #define	ZFS_DEBUG
 #undef 	NDEBUG
 #endif
diff --git a/include/os/freebsd/spl/sys/file.h b/include/os/freebsd/spl/sys/file.h
index 0d0be44f8a..51e59b1133 100644
--- a/include/os/freebsd/spl/sys/file.h
+++ b/include/os/freebsd/spl/sys/file.h
@@ -30,7 +30,6 @@
 #define	_OPENSOLARIS_SYS_FILE_H_
 
 #include <sys/refcount.h>
-#include_next <sys/refcount.h>
 #include_next <sys/file.h>
 
 #define	FKIOCTL	0x80000000	/* ioctl addresses are from kernel */
diff --git a/include/os/freebsd/spl/sys/vnode.h b/include/os/freebsd/spl/sys/vnode.h
index e330bc079f..b9fae99ad2 100644
--- a/include/os/freebsd/spl/sys/vnode.h
+++ b/include/os/freebsd/spl/sys/vnode.h
@@ -53,7 +53,7 @@ enum symfollow { NO_FOLLOW = NOFOLLOW };
 #include <sys/mount.h>
 #include <sys/cred.h>
 #include <sys/fcntl.h>
-#include_next <sys/refcount.h>
+#include <sys/refcount.h>
 #include <sys/file.h>
 #include <sys/filedesc.h>
 #include <sys/syscallsubr.h>
diff --git a/include/sys/Makefile.am b/include/sys/Makefile.am
index 0659c6419d..cbe21b7914 100644
--- a/include/sys/Makefile.am
+++ b/include/sys/Makefile.am
@@ -57,7 +57,6 @@ COMMON_H = \
 	pathname.h \
 	qat.h \
 	range_tree.h \
-	refcount.h \
 	rrwlock.h \
 	sa.h \
 	sa_impl.h \
@@ -111,6 +110,7 @@ COMMON_H = \
 	zfs_project.h \
 	zfs_quota.h \
 	zfs_ratelimit.h \
+	zfs_refcount.h \
 	zfs_rlock.h \
 	zfs_sa.h \
 	zfs_stat.h \
diff --git a/include/sys/abd.h b/include/sys/abd.h
index e9bd0e96f1..735a131475 100644
--- a/include/sys/abd.h
+++ b/include/sys/abd.h
@@ -28,7 +28,7 @@
 
 #include <sys/isa_defs.h>
 #include <sys/debug.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #include <sys/uio.h>
 
 #ifdef __cplusplus
diff --git a/include/sys/arc.h b/include/sys/arc.h
index f358bc9ae5..f322d6328f 100644
--- a/include/sys/arc.h
+++ b/include/sys/arc.h
@@ -36,7 +36,7 @@ extern "C" {
 #include <sys/zio.h>
 #include <sys/dmu.h>
 #include <sys/spa.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 
 /*
  * Used by arc_flush() to inform arc_evict_state() that it should evict
diff --git a/include/sys/dbuf.h b/include/sys/dbuf.h
index d04e08baaf..04338b2c49 100644
--- a/include/sys/dbuf.h
+++ b/include/sys/dbuf.h
@@ -34,7 +34,7 @@
 #include <sys/zio.h>
 #include <sys/arc.h>
 #include <sys/zfs_context.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #include <sys/zrlock.h>
 #include <sys/multilist.h>
 
diff --git a/include/sys/dmu_tx.h b/include/sys/dmu_tx.h
index 36d205e950..60e9ed6e26 100644
--- a/include/sys/dmu_tx.h
+++ b/include/sys/dmu_tx.h
@@ -32,7 +32,7 @@
 #include <sys/inttypes.h>
 #include <sys/dmu.h>
 #include <sys/txg.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 
 #ifdef	__cplusplus
 extern "C" {
diff --git a/include/sys/dnode.h b/include/sys/dnode.h
index 14821bab27..3208b60f0e 100644
--- a/include/sys/dnode.h
+++ b/include/sys/dnode.h
@@ -32,7 +32,7 @@
 #include <sys/spa.h>
 #include <sys/txg.h>
 #include <sys/zio.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #include <sys/dmu_zfetch.h>
 #include <sys/zrlock.h>
 #include <sys/multilist.h>
diff --git a/include/sys/dsl_bookmark.h b/include/sys/dsl_bookmark.h
index 73424e5a86..70f4813449 100644
--- a/include/sys/dsl_bookmark.h
+++ b/include/sys/dsl_bookmark.h
@@ -20,7 +20,7 @@
 #define	_SYS_DSL_BOOKMARK_H
 
 #include <sys/zfs_context.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #include <sys/dsl_dataset.h>
 #include <sys/dsl_pool.h>
 
diff --git a/include/sys/dsl_dataset.h b/include/sys/dsl_dataset.h
index 77fa440f25..90cb68927a 100644
--- a/include/sys/dsl_dataset.h
+++ b/include/sys/dsl_dataset.h
@@ -36,7 +36,7 @@
 #include <sys/dsl_synctask.h>
 #include <sys/zfs_context.h>
 #include <sys/dsl_deadlist.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #include <sys/rrwlock.h>
 #include <sys/dsl_crypt.h>
 #include <zfeature_common.h>
diff --git a/include/sys/dsl_dir.h b/include/sys/dsl_dir.h
index b894bcfff6..7cf5093c2c 100644
--- a/include/sys/dsl_dir.h
+++ b/include/sys/dsl_dir.h
@@ -32,7 +32,7 @@
 #include <sys/dsl_deadlist.h>
 #include <sys/dsl_pool.h>
 #include <sys/dsl_synctask.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #include <sys/zfs_context.h>
 #include <sys/dsl_crypt.h>
 #include <sys/bplist.h>
diff --git a/include/sys/rrwlock.h b/include/sys/rrwlock.h
index 935a7ee940..8d296ef28f 100644
--- a/include/sys/rrwlock.h
+++ b/include/sys/rrwlock.h
@@ -37,7 +37,7 @@ extern "C" {
 
 #include <sys/inttypes.h>
 #include <sys/zfs_context.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 
 extern uint_t rrw_tsd_key;
 
diff --git a/include/sys/sa_impl.h b/include/sys/sa_impl.h
index 7eddd8750f..fa10aff8a3 100644
--- a/include/sys/sa_impl.h
+++ b/include/sys/sa_impl.h
@@ -28,7 +28,7 @@
 #define	_SYS_SA_IMPL_H
 
 #include <sys/dmu.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #include <sys/list.h>
 
 /*
diff --git a/include/sys/spa_impl.h b/include/sys/spa_impl.h
index 2c52cb666f..69de75fb6d 100644
--- a/include/sys/spa_impl.h
+++ b/include/sys/spa_impl.h
@@ -44,7 +44,7 @@
 #include <sys/uberblock_impl.h>
 #include <sys/zfs_context.h>
 #include <sys/avl.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #include <sys/bplist.h>
 #include <sys/bpobj.h>
 #include <sys/dsl_crypt.h>
diff --git a/include/sys/refcount.h b/include/sys/zfs_refcount.h
similarity index 98%
rename from include/sys/refcount.h
rename to include/sys/zfs_refcount.h
index c8f5862303..fc0cbea1cf 100644
--- a/include/sys/refcount.h
+++ b/include/sys/zfs_refcount.h
@@ -23,8 +23,8 @@
  * Copyright (c) 2012, 2015 by Delphix. All rights reserved.
  */
 
-#ifndef	_SYS_REFCOUNT_H
-#define	_SYS_REFCOUNT_H
+#ifndef	_SYS_ZFS_REFCOUNT_H
+#define	_SYS_ZFS_REFCOUNT_H
 
 #include <sys/inttypes.h>
 #include <sys/list.h>
diff --git a/include/sys/zio_crypt.h b/include/sys/zio_crypt.h
index 6b7bf719ef..d7a63d6958 100644
--- a/include/sys/zio_crypt.h
+++ b/include/sys/zio_crypt.h
@@ -21,7 +21,7 @@
 #define	_SYS_ZIO_CRYPT_H
 
 #include <sys/dmu.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #if defined(__FreeBSD__) && defined(_KERNEL)
 #include <sys/freebsd_crypto.h>
 #else
diff --git a/lib/libzpool/util.c b/lib/libzpool/util.c
index df1084cb6d..ebfaa9b41a 100644
--- a/lib/libzpool/util.c
+++ b/lib/libzpool/util.c
@@ -33,7 +33,7 @@
 #include <stdlib.h>
 #include <sys/spa.h>
 #include <sys/fs/zfs.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #include <sys/zfs_ioctl.h>
 #include <dlfcn.h>
 #include <libzutil.h>
diff --git a/module/os/freebsd/spl/spl_vfs.c b/module/os/freebsd/spl/spl_vfs.c
index d42835c202..6d308adb43 100644
--- a/module/os/freebsd/spl/spl_vfs.c
+++ b/module/os/freebsd/spl/spl_vfs.c
@@ -40,6 +40,7 @@ __FBSDID("$FreeBSD$");
 
 #include <sys/mutex.h>
 #include <sys/vnode.h>
+#include <sys/taskq.h>
 
 #include <sys/ccompat.h>
 
diff --git a/module/os/freebsd/zfs/arc_os.c b/module/os/freebsd/zfs/arc_os.c
index b3deff0f0c..554896d856 100644
--- a/module/os/freebsd/zfs/arc_os.c
+++ b/module/os/freebsd/zfs/arc_os.c
@@ -26,7 +26,7 @@
 #include <sys/zio_checksum.h>
 #include <sys/zfs_context.h>
 #include <sys/arc.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #include <sys/vdev.h>
 #include <sys/vdev_trim.h>
 #include <sys/vdev_impl.h>
diff --git a/module/os/freebsd/zfs/zfs_fuid_os.c b/module/os/freebsd/zfs/zfs_fuid_os.c
index ebd09abd65..72655d7ff6 100644
--- a/module/os/freebsd/zfs/zfs_fuid_os.c
+++ b/module/os/freebsd/zfs/zfs_fuid_os.c
@@ -26,7 +26,6 @@
 #include <sys/dmu.h>
 #include <sys/avl.h>
 #include <sys/zap.h>
-#include <sys/refcount.h>
 #include <sys/nvpair.h>
 #ifdef _KERNEL
 #include <sys/sid.h>
diff --git a/module/os/freebsd/zfs/zfs_vnops.c b/module/os/freebsd/zfs/zfs_vnops.c
index 14ad71d11e..742b295066 100644
--- a/module/os/freebsd/zfs/zfs_vnops.c
+++ b/module/os/freebsd/zfs/zfs_vnops.c
@@ -36,6 +36,7 @@
 #include <sys/sysmacros.h>
 #include <sys/resource.h>
 #include <sys/vfs.h>
+#include <sys/endian.h>
 #include <sys/vm.h>
 #include <sys/vnode.h>
 #include <sys/dirent.h>
diff --git a/module/os/freebsd/zfs/zfs_znode.c b/module/os/freebsd/zfs/zfs_znode.c
index badf159ca1..a448706121 100644
--- a/module/os/freebsd/zfs/zfs_znode.c
+++ b/module/os/freebsd/zfs/zfs_znode.c
@@ -56,14 +56,13 @@
 #include <sys/dmu.h>
 #include <sys/dmu_objset.h>
 #include <sys/dmu_tx.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #include <sys/stat.h>
 #include <sys/zap.h>
 #include <sys/zfs_znode.h>
 #include <sys/sa.h>
 #include <sys/zfs_sa.h>
 #include <sys/zfs_stat.h>
-#include <sys/refcount.h>
 
 #include "zfs_prop.h"
 #include "zfs_comutil.h"
diff --git a/module/os/freebsd/zfs/zvol_os.c b/module/os/freebsd/zfs/zvol_os.c
index d601c72515..22fc64558d 100644
--- a/module/os/freebsd/zfs/zvol_os.c
+++ b/module/os/freebsd/zfs/zvol_os.c
@@ -78,7 +78,6 @@
 #include <sys/fs/zfs.h>
 #include <sys/zfs_ioctl.h>
 #include <sys/zil.h>
-#include <sys/refcount.h>
 #include <sys/zfs_znode.h>
 #include <sys/zfs_rlock.h>
 #include <sys/vdev_impl.h>
diff --git a/module/os/linux/zfs/arc_os.c b/module/os/linux/zfs/arc_os.c
index e9c0f349d5..9c3a6a4e29 100644
--- a/module/os/linux/zfs/arc_os.c
+++ b/module/os/linux/zfs/arc_os.c
@@ -33,7 +33,7 @@
 #include <sys/zio_checksum.h>
 #include <sys/zfs_context.h>
 #include <sys/arc.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #include <sys/vdev.h>
 #include <sys/vdev_trim.h>
 #include <sys/vdev_impl.h>
diff --git a/module/os/linux/zfs/zfs_znode.c b/module/os/linux/zfs/zfs_znode.c
index 504dc76f92..a542c662cb 100644
--- a/module/os/linux/zfs/zfs_znode.c
+++ b/module/os/linux/zfs/zfs_znode.c
@@ -54,7 +54,7 @@
 #include <sys/dmu.h>
 #include <sys/dmu_objset.h>
 #include <sys/dmu_tx.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #include <sys/stat.h>
 #include <sys/zap.h>
 #include <sys/zfs_znode.h>
diff --git a/module/zfs/arc.c b/module/zfs/arc.c
index 9e9227271d..dcf710ad14 100644
--- a/module/zfs/arc.c
+++ b/module/zfs/arc.c
@@ -284,7 +284,7 @@
 #include <sys/zio_checksum.h>
 #include <sys/zfs_context.h>
 #include <sys/arc.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #include <sys/vdev.h>
 #include <sys/vdev_impl.h>
 #include <sys/dsl_pool.h>
diff --git a/module/zfs/bpobj.c b/module/zfs/bpobj.c
index 00c3d7dfa8..e75ba5cccd 100644
--- a/module/zfs/bpobj.c
+++ b/module/zfs/bpobj.c
@@ -26,7 +26,7 @@
 
 #include <sys/bpobj.h>
 #include <sys/zfs_context.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 #include <sys/dsl_pool.h>
 #include <sys/zfeature.h>
 #include <sys/zap.h>
diff --git a/module/zfs/bptree.c b/module/zfs/bptree.c
index 1642162133..1827a3c4e3 100644
--- a/module/zfs/bptree.c
+++ b/module/zfs/bptree.c
@@ -33,7 +33,6 @@
 #include <sys/dsl_dir.h>
 #include <sys/dsl_pool.h>
 #include <sys/dnode.h>
-#include <sys/refcount.h>
 #include <sys/spa.h>
 
 /*
diff --git a/module/zfs/dsl_deadlist.c b/module/zfs/dsl_deadlist.c
index 8cb0f90fb8..3d16f61f62 100644
--- a/module/zfs/dsl_deadlist.c
+++ b/module/zfs/dsl_deadlist.c
@@ -25,7 +25,6 @@
  */
 
 #include <sys/dmu.h>
-#include <sys/refcount.h>
 #include <sys/zap.h>
 #include <sys/zfs_context.h>
 #include <sys/dsl_pool.h>
diff --git a/module/zfs/refcount.c b/module/zfs/refcount.c
index 6c9c305eda..39476261ed 100644
--- a/module/zfs/refcount.c
+++ b/module/zfs/refcount.c
@@ -24,7 +24,7 @@
  */
 
 #include <sys/zfs_context.h>
-#include <sys/refcount.h>
+#include <sys/zfs_refcount.h>
 
 /*
  * Reference count tracking is disabled by default.  It's memory requirements
diff --git a/module/zfs/rrwlock.c b/module/zfs/rrwlock.c
index a2b7848374..d23fc3ad10 100644
--- a/module/zfs/rrwlock.c
+++ b/module/zfs/rrwlock.c
@@ -26,7 +26,6 @@
  * Copyright (c) 2012 by Delphix. All rights reserved.
  */
 
-#include <sys/refcount.h>
 #include <sys/rrwlock.h>
 #include <sys/trace_zfs.h>
 
diff --git a/module/zfs/space_map.c b/module/zfs/space_map.c
index 723fa05784..3db7d19919 100644
--- a/module/zfs/space_map.c
+++ b/module/zfs/space_map.c
@@ -34,7 +34,6 @@
 #include <sys/dsl_pool.h>
 #include <sys/zio.h>
 #include <sys/space_map.h>
-#include <sys/refcount.h>
 #include <sys/zfeature.h>
 
 /*
diff --git a/module/zfs/vdev_indirect.c b/module/zfs/vdev_indirect.c
index fc49bad065..4cd83d79ea 100644
--- a/module/zfs/vdev_indirect.c
+++ b/module/zfs/vdev_indirect.c
@@ -27,7 +27,6 @@
 #include <sys/zio.h>
 #include <sys/zio_checksum.h>
 #include <sys/metaslab.h>
-#include <sys/refcount.h>
 #include <sys/dmu.h>
 #include <sys/vdev_indirect_mapping.h>
 #include <sys/dmu_tx.h>
diff --git a/module/zfs/vdev_initialize.c b/module/zfs/vdev_initialize.c
index 0d45d9958e..ab711441d9 100644
--- a/module/zfs/vdev_initialize.c
+++ b/module/zfs/vdev_initialize.c
@@ -27,7 +27,6 @@
 #include <sys/spa_impl.h>
 #include <sys/txg.h>
 #include <sys/vdev_impl.h>
-#include <sys/refcount.h>
 #include <sys/metaslab_impl.h>
 #include <sys/dsl_synctask.h>
 #include <sys/zap.h>
diff --git a/module/zfs/vdev_trim.c b/module/zfs/vdev_trim.c
index 0254c29043..a655e2fd2a 100644
--- a/module/zfs/vdev_trim.c
+++ b/module/zfs/vdev_trim.c
@@ -29,7 +29,6 @@
 #include <sys/txg.h>
 #include <sys/vdev_impl.h>
 #include <sys/vdev_trim.h>
-#include <sys/refcount.h>
 #include <sys/metaslab_impl.h>
 #include <sys/dsl_synctask.h>
 #include <sys/zap.h>
diff --git a/module/zfs/zap.c b/module/zfs/zap.c
index 1abb32fdf0..c0c280c520 100644
--- a/module/zfs/zap.c
+++ b/module/zfs/zap.c
@@ -45,7 +45,6 @@
 #include <sys/zfs_znode.h>
 #include <sys/fs/zfs.h>
 #include <sys/zap.h>
-#include <sys/refcount.h>
 #include <sys/zap_impl.h>
 #include <sys/zap_leaf.h>
 
diff --git a/module/zfs/zap_micro.c b/module/zfs/zap_micro.c
index 644f4bab1f..5d9bc20760 100644
--- a/module/zfs/zap_micro.c
+++ b/module/zfs/zap_micro.c
@@ -31,7 +31,6 @@
 #include <sys/dmu.h>
 #include <sys/zfs_context.h>
 #include <sys/zap.h>
-#include <sys/refcount.h>
 #include <sys/zap_impl.h>
 #include <sys/zap_leaf.h>
 #include <sys/avl.h>
diff --git a/module/zfs/zfs_fuid.c b/module/zfs/zfs_fuid.c
index fbd06be4f9..726b923fac 100644
--- a/module/zfs/zfs_fuid.c
+++ b/module/zfs/zfs_fuid.c
@@ -26,7 +26,6 @@
 #include <sys/dmu.h>
 #include <sys/avl.h>
 #include <sys/zap.h>
-#include <sys/refcount.h>
 #include <sys/nvpair.h>
 #ifdef _KERNEL
 #include <sys/sid.h>