diff --git a/include/os/freebsd/spl/sys/atomic.h b/include/os/freebsd/spl/sys/atomic.h
index 01b13fc9afd7..8b9cec15c5e1 100644
--- a/include/os/freebsd/spl/sys/atomic.h
+++ b/include/os/freebsd/spl/sys/atomic.h
@@ -59,6 +59,7 @@ extern uint64_t atomic_cas_64(volatile uint64_t *target, uint64_t cmp,
 
 #define	membar_consumer()		atomic_thread_fence_acq()
 #define	membar_producer()		atomic_thread_fence_rel()
+#define	membar_sync()			atomic_thread_fence_seq_cst()
 
 static __inline uint32_t
 atomic_add_32_nv(volatile uint32_t *target, int32_t delta)
diff --git a/include/os/linux/spl/sys/vmsystm.h b/include/os/linux/spl/sys/vmsystm.h
index fcd61e818fa3..c6d99fb3183d 100644
--- a/include/os/linux/spl/sys/vmsystm.h
+++ b/include/os/linux/spl/sys/vmsystm.h
@@ -46,6 +46,7 @@
 
 #define	membar_consumer()		smp_rmb()
 #define	membar_producer()		smp_wmb()
+#define	membar_sync()			smp_mb()
 
 #define	physmem				zfs_totalram_pages
 
diff --git a/lib/libspl/atomic.c b/lib/libspl/atomic.c
index ba14b113f585..8cc350710ba0 100644
--- a/lib/libspl/atomic.c
+++ b/lib/libspl/atomic.c
@@ -381,6 +381,12 @@ membar_exit(void)
 	__atomic_thread_fence(__ATOMIC_SEQ_CST);
 }
 
+void
+membar_sync(void)
+{
+	__atomic_thread_fence(__ATOMIC_SEQ_CST);
+}
+
 void
 membar_producer(void)
 {
diff --git a/lib/libspl/include/atomic.h b/lib/libspl/include/atomic.h
index 1249d42b604a..4ebdbbda9864 100644
--- a/lib/libspl/include/atomic.h
+++ b/lib/libspl/include/atomic.h
@@ -313,6 +313,13 @@ extern void membar_enter(void);
  */
 extern void membar_exit(void);
 
+/*
+ * Make all stores and loads emitted prior to the the barrier complete before
+ * crossing it, while also making sure stores and loads emitted after the
+ * barrier only start being executed after crossing it.
+ */
+extern void membar_sync(void);
+
 /*
  * Arrange that all stores issued before this point in the code reach
  * global visibility before any stores that follow; useful in producer