md/raid5: add simple plugging infrastructure.
md/raid5 uses the plugging infrastructure provided by the block layer
and 'struct request_queue'. However when we plug raid5 under dm there
is no request queue so we cannot use that.
So create a similar infrastructure that is much lighter weight and use
it for raid5.
Signed-off-by: NeilBrown <neilb@suse.de>
diff --git a/drivers/md/md.c b/drivers/md/md.c
index f877569..eec75f1 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -386,6 +386,51 @@
}
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);