1 files changed, 1 insertions, 0 deletions

diff --git a/include/linux/backing-dev-defs.h b/include/linux/backing-dev-defs.h
index c31157135598..07e02d6df5ad 100644
--- a/include/linux/backing-dev-defs.h
+++ b/include/linux/backing-dev-defs.h
@@ -190,6 +190,7 @@ struct backing_dev_info {
         struct radix_tree_root cgwb_tree; /* radix tree of active cgroup wbs */
         struct rb_root cgwb_congested_tree; /* their congested states */
         struct mutex cgwb_release_mutex;  /* protect shutdown of wb structs */
+        struct rw_semaphore wb_switch_rwsem; /* no cgwb switch while syncing */
 #else
         struct bdi_writeback_congested *wb_congested;
 #endif