diff --git a/fs/btrfs/volumes.h b/fs/btrfs/volumes.h
index 2185de7..5836327 100644
--- a/fs/btrfs/volumes.h
+++ b/fs/btrfs/volumes.h
@@ -23,13 +23,22 @@
 #include "async-thread.h"
 
 struct buffer_head;
+struct btrfs_pending_bios {
+	struct bio *head;
+	struct bio *tail;
+};
+
 struct btrfs_device {
 	struct list_head dev_list;
 	struct list_head dev_alloc_list;
 	struct btrfs_fs_devices *fs_devices;
 	struct btrfs_root *dev_root;
-	struct bio *pending_bios;
-	struct bio *pending_bio_tail;
+
+	/* regular prio bios */
+	struct btrfs_pending_bios pending_bios;
+	/* WRITE_SYNC bios */
+	struct btrfs_pending_bios pending_sync_bios;
+
 	int running_pending;
 	u64 generation;