1 files changed, 50 insertions, 0 deletions
diff --git a/drivers/md/dm-vdo/indexer/index-page-map.h b/drivers/md/dm-vdo/indexer/index-page-map.h
new file mode 100644
index 000000000000..b327c0bb9656
--- /dev/null
+++ b/drivers/md/dm-vdo/indexer/index-page-map.h
@@ -0,0 +1,50 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#ifndef UDS_INDEX_PAGE_MAP_H
+#define UDS_INDEX_PAGE_MAP_H
+
+#include "geometry.h"
+#include "io-factory.h"
+
+/*
+ * The index maintains a page map which records how the chapter delta lists are distributed among
+ * the index pages for each chapter, allowing the volume to be efficient about reading only pages
+ * that it knows it will need.
+ */
+
+struct index_page_map {
+	const struct index_geometry *geometry;
+	u64 last_update;
+	u32 entries_per_chapter;
+	u16 *entries;
+};
+
+int __must_check uds_make_index_page_map(const struct index_geometry *geometry,
+					 struct index_page_map **map_ptr);
+
+void uds_free_index_page_map(struct index_page_map *map);
+
+int __must_check uds_read_index_page_map(struct index_page_map *map,
+					 struct buffered_reader *reader);
+
+int __must_check uds_write_index_page_map(struct index_page_map *map,
+					  struct buffered_writer *writer);
+
+void uds_update_index_page_map(struct index_page_map *map, u64 virtual_chapter_number,
+			       u32 chapter_number, u32 index_page_number,
+			       u32 delta_list_number);
+
+u32 __must_check uds_find_index_page_number(const struct index_page_map *map,
+					    const struct uds_record_name *name,
+					    u32 chapter_number);
+
+void uds_get_list_number_bounds(const struct index_page_map *map, u32 chapter_number,
+				u32 index_page_number, u32 *lowest_list,
+				u32 *highest_list);
+
+u64 uds_compute_index_page_map_save_size(const struct index_geometry *geometry);
+
+#endif /* UDS_INDEX_PAGE_MAP_H */