Add a real API for dealing with blk_congestion_wait()

Signed-off-by: Trond Myklebust <Trond.Myklebust@netapp.com>
diff --git a/fs/nfs/write.c b/fs/nfs/write.c
index 453d446..38ba5c0 100644
--- a/fs/nfs/write.c
+++ b/fs/nfs/write.c
@@ -396,6 +396,7 @@
 out:
 	clear_bit(BDI_write_congested, &bdi->state);
 	wake_up_all(&nfs_write_congestion);
+	writeback_congestion_end();
 	return err;
 }