v4.19.13 snapshot.
diff --git a/fs/btrfs/ref-verify.h b/fs/btrfs/ref-verify.h
new file mode 100644
index 0000000..b7d2a4e
--- /dev/null
+++ b/fs/btrfs/ref-verify.h
@@ -0,0 +1,51 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2014 Facebook. All rights reserved.
+ */
+
+#ifndef BTRFS_REF_VERIFY_H
+#define BTRFS_REF_VERIFY_H
+
+#ifdef CONFIG_BTRFS_FS_REF_VERIFY
+int btrfs_build_ref_tree(struct btrfs_fs_info *fs_info);
+void btrfs_free_ref_cache(struct btrfs_fs_info *fs_info);
+int btrfs_ref_tree_mod(struct btrfs_root *root, u64 bytenr, u64 num_bytes,
+ u64 parent, u64 ref_root, u64 owner, u64 offset,
+ int action);
+void btrfs_free_ref_tree_range(struct btrfs_fs_info *fs_info, u64 start,
+ u64 len);
+
+static inline void btrfs_init_ref_verify(struct btrfs_fs_info *fs_info)
+{
+ spin_lock_init(&fs_info->ref_verify_lock);
+ fs_info->block_tree = RB_ROOT;
+}
+#else
+static inline int btrfs_build_ref_tree(struct btrfs_fs_info *fs_info)
+{
+ return 0;
+}
+
+static inline void btrfs_free_ref_cache(struct btrfs_fs_info *fs_info)
+{
+}
+
+static inline int btrfs_ref_tree_mod(struct btrfs_root *root, u64 bytenr,
+ u64 num_bytes, u64 parent, u64 ref_root,
+ u64 owner, u64 offset, int action)
+{
+ return 0;
+}
+
+static inline void btrfs_free_ref_tree_range(struct btrfs_fs_info *fs_info,
+ u64 start, u64 len)
+{
+}
+
+static inline void btrfs_init_ref_verify(struct btrfs_fs_info *fs_info)
+{
+}
+
+#endif /* CONFIG_BTRFS_FS_REF_VERIFY */
+
+#endif