2 files changed, 22 insertions, 0 deletions

diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h
index 6a1a8a314d85..8fb740178d5d 100644
--- a/include/linux/backing-dev-defs.h
+++ b/include/linux/backing-dev-defs.h
@@ -67,6 +67,26 @@ enum wb_reason {
         WB_REASON_MAX,
 };
 
+struct wb_completion {
+        atomic_t                cnt;
+        wait_queue_head_t       *waitq;
+};
+
+#define __WB_COMPLETION_INIT(_waitq)    \
+        (struct wb_completion){ .cnt = ATOMIC_INIT(1), .waitq = (_waitq) }
+
+/*
+ * If one wants to wait for one or more wb_writeback_works, each work's
+ * ->done should be set to a wb_completion defined using the following
+ * macro.  Once all work items are issued with wb_queue_work(), the caller
+ * can wait for the completion of all using wb_wait_for_completion().  Work
+ * items which are waited upon aren't freed automatically on completion.
+ */
+#define WB_COMPLETION_INIT(bdi)         __WB_COMPLETION_INIT(&(bdi)->wb_waitq)
+
+#define DEFINE_WB_COMPLETION(cmpl, bdi) \
+        struct wb_completion cmpl = WB_COMPLETION_INIT(bdi)
+
 /*
  * For cgroup writeback, multiple wb's may map to the same blkcg.  Those
  * wb's can operate mostly independently but should share the congested
diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h
index 35b31d176f74..02650b1253a2 100644
--- a/include/linux/backing-dev.h
+++ b/include/linux/backing-dev.h
@@ -44,6 +44,8 @@ void wb_start_background_writeback(struct bdi_writeback *wb);
 void wb_workfn(struct work_struct *work);
 void wb_wakeup_delayed(struct bdi_writeback *wb);
 
+void wb_wait_for_completion(struct wb_completion *done);
+
 extern spinlock_t bdi_lock;
 extern struct list_head bdi_list;