1 files changed, 66 insertions, 0 deletions
diff --git a/drivers/md/dm-vdo/indexer/hash-utils.h b/drivers/md/dm-vdo/indexer/hash-utils.h
new file mode 100644
index 000000000000..6a8dd8ffea6c
--- /dev/null
+++ b/drivers/md/dm-vdo/indexer/hash-utils.h
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#ifndef UDS_HASH_UTILS_H
+#define UDS_HASH_UTILS_H
+
+#include "numeric.h"
+
+#include "geometry.h"
+#include "indexer.h"
+
+/* Utilities for extracting portions of a request name for various uses. */
+
+/* How various portions of a record name are apportioned. */
+enum {
+	VOLUME_INDEX_BYTES_OFFSET = 0,
+	VOLUME_INDEX_BYTES_COUNT = 8,
+	CHAPTER_INDEX_BYTES_OFFSET = 8,
+	CHAPTER_INDEX_BYTES_COUNT = 6,
+	SAMPLE_BYTES_OFFSET = 14,
+	SAMPLE_BYTES_COUNT = 2,
+};
+
+static inline u64 uds_extract_chapter_index_bytes(const struct uds_record_name *name)
+{
+	const u8 *chapter_bits = &name->name[CHAPTER_INDEX_BYTES_OFFSET];
+	u64 bytes = (u64) get_unaligned_be16(chapter_bits) << 32;
+
+	bytes |= get_unaligned_be32(chapter_bits + 2);
+	return bytes;
+}
+
+static inline u64 uds_extract_volume_index_bytes(const struct uds_record_name *name)
+{
+	return get_unaligned_be64(&name->name[VOLUME_INDEX_BYTES_OFFSET]);
+}
+
+static inline u32 uds_extract_sampling_bytes(const struct uds_record_name *name)
+{
+	return get_unaligned_be16(&name->name[SAMPLE_BYTES_OFFSET]);
+}
+
+/* Compute the chapter delta list for a given name. */
+static inline u32 uds_hash_to_chapter_delta_list(const struct uds_record_name *name,
+						 const struct index_geometry *geometry)
+{
+	return ((uds_extract_chapter_index_bytes(name) >> geometry->chapter_address_bits) &
+		((1 << geometry->chapter_delta_list_bits) - 1));
+}
+
+/* Compute the chapter delta address for a given name. */
+static inline u32 uds_hash_to_chapter_delta_address(const struct uds_record_name *name,
+						    const struct index_geometry *geometry)
+{
+	return uds_extract_chapter_index_bytes(name) & ((1 << geometry->chapter_address_bits) - 1);
+}
+
+static inline unsigned int uds_name_to_hash_slot(const struct uds_record_name *name,
+						 unsigned int slot_count)
+{
+	return (unsigned int) (uds_extract_chapter_index_bytes(name) % slot_count);
+}
+
+#endif /* UDS_HASH_UTILS_H */