v4.19.13 snapshot.
diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h
new file mode 100644
index 0000000..54d5898
--- /dev/null
+++ b/fs/btrfs/backref.h
@@ -0,0 +1,76 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+/*
+ * Copyright (C) 2011 STRATO. All rights reserved.
+ */
+
+#ifndef BTRFS_BACKREF_H
+#define BTRFS_BACKREF_H
+
+#include <linux/btrfs.h>
+#include "ulist.h"
+#include "extent_io.h"
+
+struct inode_fs_paths {
+ struct btrfs_path *btrfs_path;
+ struct btrfs_root *fs_root;
+ struct btrfs_data_container *fspath;
+};
+
+typedef int (iterate_extent_inodes_t)(u64 inum, u64 offset, u64 root,
+ void *ctx);
+
+int extent_from_logical(struct btrfs_fs_info *fs_info, u64 logical,
+ struct btrfs_path *path, struct btrfs_key *found_key,
+ u64 *flags);
+
+int tree_backref_for_extent(unsigned long *ptr, struct extent_buffer *eb,
+ struct btrfs_key *key, struct btrfs_extent_item *ei,
+ u32 item_size, u64 *out_root, u8 *out_level);
+
+int iterate_extent_inodes(struct btrfs_fs_info *fs_info,
+ u64 extent_item_objectid,
+ u64 extent_offset, int search_commit_root,
+ iterate_extent_inodes_t *iterate, void *ctx,
+ bool ignore_offset);
+
+int iterate_inodes_from_logical(u64 logical, struct btrfs_fs_info *fs_info,
+ struct btrfs_path *path,
+ iterate_extent_inodes_t *iterate, void *ctx,
+ bool ignore_offset);
+
+int paths_from_inode(u64 inum, struct inode_fs_paths *ipath);
+
+int btrfs_find_all_roots(struct btrfs_trans_handle *trans,
+ struct btrfs_fs_info *fs_info, u64 bytenr,
+ u64 time_seq, struct ulist **roots, bool ignore_offset);
+char *btrfs_ref_to_path(struct btrfs_root *fs_root, struct btrfs_path *path,
+ u32 name_len, unsigned long name_off,
+ struct extent_buffer *eb_in, u64 parent,
+ char *dest, u32 size);
+
+struct btrfs_data_container *init_data_container(u32 total_bytes);
+struct inode_fs_paths *init_ipath(s32 total_bytes, struct btrfs_root *fs_root,
+ struct btrfs_path *path);
+void free_ipath(struct inode_fs_paths *ipath);
+
+int btrfs_find_one_extref(struct btrfs_root *root, u64 inode_objectid,
+ u64 start_off, struct btrfs_path *path,
+ struct btrfs_inode_extref **ret_extref,
+ u64 *found_off);
+int btrfs_check_shared(struct btrfs_root *root, u64 inum, u64 bytenr);
+
+int __init btrfs_prelim_ref_init(void);
+void __cold btrfs_prelim_ref_exit(void);
+
+struct prelim_ref {
+ struct rb_node rbnode;
+ u64 root_id;
+ struct btrfs_key key_for_search;
+ int level;
+ int count;
+ struct extent_inode_elem *inode_list;
+ u64 parent;
+ u64 wanted_disk_byte;
+};
+
+#endif