1 files changed, 45 insertions, 0 deletions

diff --git a/drivers/md/md.c b/drivers/md/md.c
index f8775699e15a..eec75f130708 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -386,6 +386,51 @@ void md_barrier_request(mddev_t *mddev, struct bio *bio)
 }
 EXPORT_SYMBOL(md_barrier_request);
 
+/* Support for plugging.
+ * This mirrors the plugging support in request_queue, but does not
+ * require having a whole queue
+ */
+static void plugger_work(struct work_struct *work)
+{
+        struct plug_handle *plug =
+                container_of(work, struct plug_handle, unplug_work);
+        plug->unplug_fn(plug);
+}
+static void plugger_timeout(unsigned long data)
+{
+        struct plug_handle *plug = (void *)data;
+        kblockd_schedule_work(NULL, &plug->unplug_work);
+}
+void plugger_init(struct plug_handle *plug,
+                  void (*unplug_fn)(struct plug_handle *))
+{
+        plug->unplug_flag = 0;
+        plug->unplug_fn = unplug_fn;
+        init_timer(&plug->unplug_timer);
+        plug->unplug_timer.function = plugger_timeout;
+        plug->unplug_timer.data = (unsigned long)plug;
+        INIT_WORK(&plug->unplug_work, plugger_work);
+}
+EXPORT_SYMBOL_GPL(plugger_init);
+
+void plugger_set_plug(struct plug_handle *plug)
+{
+        if (!test_and_set_bit(PLUGGED_FLAG, &plug->unplug_flag))
+                mod_timer(&plug->unplug_timer, jiffies + msecs_to_jiffies(3)+1);
+}
+EXPORT_SYMBOL_GPL(plugger_set_plug);
+
+int plugger_remove_plug(struct plug_handle *plug)
+{
+        if (test_and_clear_bit(PLUGGED_FLAG, &plug->unplug_flag)) {
+                del_timer(&plug->unplug_timer);
+                return 1;
+        } else
+                return 0;
+}
+EXPORT_SYMBOL_GPL(plugger_remove_plug);
+
+
 static inline mddev_t *mddev_get(mddev_t *mddev)
 {
         atomic_inc(&mddev->active);