Merge branch 'md-next' into md-linus

1 files changed, 17 insertions, 0 deletions

diff --git a/lib/percpu-refcount.c b/lib/percpu-refcount.c
index 9ac959ef4cae9..fe03c6d527611 100644
--- a/lib/percpu-refcount.c
+++ b/lib/percpu-refcount.c
@@ -260,6 +260,22 @@ void percpu_ref_switch_to_atomic(struct percpu_ref *ref,
 
 	spin_unlock_irqrestore(&percpu_ref_switch_lock, flags);
 }
+EXPORT_SYMBOL_GPL(percpu_ref_switch_to_atomic);
+
+/**
+ * percpu_ref_switch_to_atomic_sync - switch a percpu_ref to atomic mode
+ * @ref: percpu_ref to switch to atomic mode
+ *
+ * Schedule switching the ref to atomic mode, and wait for the
+ * switch to complete.  Caller must ensure that no other thread
+ * will switch back to percpu mode.
+ */
+void percpu_ref_switch_to_atomic_sync(struct percpu_ref *ref)
+{
+	percpu_ref_switch_to_atomic(ref, NULL);
+	wait_event(percpu_ref_switch_waitq, !ref->confirm_switch);
+}
+EXPORT_SYMBOL_GPL(percpu_ref_switch_to_atomic_sync);
 
 /**
  * percpu_ref_switch_to_percpu - switch a percpu_ref to percpu mode
@@ -290,6 +306,7 @@ void percpu_ref_switch_to_percpu(struct percpu_ref *ref)
 
 	spin_unlock_irqrestore(&percpu_ref_switch_lock, flags);
 }
+EXPORT_SYMBOL_GPL(percpu_ref_switch_to_percpu);
 
 /**
  * percpu_ref_kill_and_confirm - drop the initial ref and schedule confirmation