new file mode 100644
@@ -0,0 +1,304 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#include "chapter-index.h"
+
+#include "errors.h"
+#include "hash-utils.h"
+#include "logger.h"
+#include "memory-alloc.h"
+#include "permassert.h"
+#include "uds.h"
+
+int uds_make_open_chapter_index(struct open_chapter_index **chapter_index,
+ const struct geometry *geometry,
+ u64 volume_nonce)
+{
+ int result;
+ size_t memory_size;
+ struct open_chapter_index *index;
+
+ result = UDS_ALLOCATE(1, struct open_chapter_index, "open chapter index", &index);
+ if (result != UDS_SUCCESS)
+ return result;
+
+ /*
+ * The delta index will rebalance delta lists when memory gets tight,
+ * so give the chapter index one extra page.
+ */
+ memory_size = ((geometry->index_pages_per_chapter + 1) * geometry->bytes_per_page);
+ index->geometry = geometry;
+ index->volume_nonce = volume_nonce;
+ result = uds_initialize_delta_index(&index->delta_index,
+ 1,
+ geometry->delta_lists_per_chapter,
+ geometry->chapter_mean_delta,
+ geometry->chapter_payload_bits,
+ memory_size,
+ 'm');
+ if (result != UDS_SUCCESS) {
+ UDS_FREE(index);
+ return result;
+ }
+
+ index->memory_size = index->delta_index.memory_size + sizeof(struct open_chapter_index);
+ *chapter_index = index;
+ return UDS_SUCCESS;
+}
+
+void uds_free_open_chapter_index(struct open_chapter_index *chapter_index)
+{
+ if (chapter_index == NULL)
+ return;
+
+ uds_uninitialize_delta_index(&chapter_index->delta_index);
+ UDS_FREE(chapter_index);
+}
+
+/* Re-initialize an open chapter index for a new chapter. */
+void uds_empty_open_chapter_index(struct open_chapter_index *chapter_index,
+ u64 virtual_chapter_number)
+{
+ uds_reset_delta_index(&chapter_index->delta_index);
+ chapter_index->virtual_chapter_number = virtual_chapter_number;
+}
+
+static inline bool was_entry_found(const struct delta_index_entry *entry, u32 address)
+{
+ return (!entry->at_end) && (entry->key == address);
+}
+
+/* Associate a record name with the record page containing its metadata. */
+int uds_put_open_chapter_index_record(struct open_chapter_index *chapter_index,
+ const struct uds_record_name *name,
+ u32 page_number)
+{
+ int result;
+ struct delta_index_entry entry;
+ u32 address;
+ u32 list_number;
+ const u8 *found_name;
+ bool found;
+ const struct geometry *geometry = chapter_index->geometry;
+ u64 chapter_number = chapter_index->virtual_chapter_number;
+ u32 record_pages = geometry->record_pages_per_chapter;
+
+ result = ASSERT(page_number < record_pages,
+ "Page number within chapter (%u) exceeds the maximum value %u",
+ page_number,
+ record_pages);
+ if (result != UDS_SUCCESS)
+ return UDS_INVALID_ARGUMENT;
+
+ address = uds_hash_to_chapter_delta_address(name, geometry);
+ list_number = uds_hash_to_chapter_delta_list(name, geometry);
+ result = uds_get_delta_index_entry(&chapter_index->delta_index,
+ list_number,
+ address,
+ name->name,
+ &entry);
+ if (result != UDS_SUCCESS)
+ return result;
+
+ found = was_entry_found(&entry, address);
+ result = ASSERT(!(found && entry.is_collision),
+ "Chunk appears more than once in chapter %llu",
+ (unsigned long long) chapter_number);
+ if (result != UDS_SUCCESS)
+ return UDS_BAD_STATE;
+
+ found_name = (found ? name->name : NULL);
+ return uds_put_delta_index_entry(&entry, address, page_number, found_name);
+}
+
+/*
+ * Pack a section of an open chapter index into a chapter index page. A range of delta lists
+ * (starting with a specified list index) is copied from the open chapter index into a memory page.
+ * The number of lists copied onto the page is returned to the caller on success.
+ *
+ * @chapter_index: The open chapter index
+ * @memory: The memory page to use
+ * @first_list: The first delta list number to be copied
+ * @last_page: If true, this is the last page of the chapter index and all the remaining lists must
+ * be packed onto this page
+ * @lists_packed: The number of delta lists that were packed onto this page
+ */
+int uds_pack_open_chapter_index_page(struct open_chapter_index *chapter_index,
+ u8 *memory,
+ u32 first_list,
+ bool last_page,
+ u32 *lists_packed)
+{
+ int result;
+ struct delta_index *delta_index = &chapter_index->delta_index;
+ struct delta_index_stats stats;
+ u64 nonce = chapter_index->volume_nonce;
+ u64 chapter_number = chapter_index->virtual_chapter_number;
+ const struct geometry *geometry = chapter_index->geometry;
+ u32 list_count = geometry->delta_lists_per_chapter;
+ unsigned int removals = 0;
+ struct delta_index_entry entry;
+ u32 next_list;
+ s32 list_number;
+
+ for (;;) {
+ result = uds_pack_delta_index_page(delta_index,
+ nonce,
+ memory,
+ geometry->bytes_per_page,
+ chapter_number,
+ first_list,
+ lists_packed);
+ if (result != UDS_SUCCESS)
+ return result;
+ if ((first_list + *lists_packed) == list_count)
+ /* All lists are packed. */
+ break;
+ else if (*lists_packed == 0) {
+ /*
+ * The next delta list does not fit on a page. This delta list will be
+ * removed.
+ */
+ } else if (last_page) {
+ /*
+ * This is the last page and there are lists left unpacked, but all of the
+ * remaining lists must fit on the page. Find a list that contains entries
+ * and remove the entire list. Try the first list that does not fit. If it
+ * is empty, we will select the last list that already fits and has any
+ * entries.
+ */
+ } else {
+ /* This page is done. */
+ break;
+ }
+
+ if (removals == 0) {
+ uds_get_delta_index_stats(delta_index, &stats);
+ uds_log_warning("The chapter index for chapter %llu contains %llu entries with %llu collisions",
+ (unsigned long long) chapter_number,
+ (unsigned long long) stats.record_count,
+ (unsigned long long) stats.collision_count);
+ }
+
+ list_number = *lists_packed;
+ do {
+ if (list_number < 0)
+ return UDS_OVERFLOW;
+
+ next_list = first_list + list_number--,
+ result = uds_start_delta_index_search(delta_index, next_list, 0, &entry);
+ if (result != UDS_SUCCESS)
+ return result;
+
+ result = uds_next_delta_index_entry(&entry);
+ if (result != UDS_SUCCESS)
+ return result;
+ } while (entry.at_end);
+
+ do {
+ result = uds_remove_delta_index_entry(&entry);
+ if (result != UDS_SUCCESS)
+ return result;
+ removals++;
+ } while (!entry.at_end);
+ }
+
+ if (removals > 0)
+ uds_log_warning("To avoid chapter index page overflow in chapter %llu, %u entries were removed from the chapter index",
+ (unsigned long long) chapter_number,
+ removals);
+
+ return UDS_SUCCESS;
+}
+
+/* Make a new chapter index page, initializing it with the data from a given index_page buffer. */
+int uds_initialize_chapter_index_page(struct delta_index_page *index_page,
+ const struct geometry *geometry,
+ u8 *page_buffer,
+ u64 volume_nonce)
+{
+ return uds_initialize_delta_index_page(index_page,
+ volume_nonce,
+ geometry->chapter_mean_delta,
+ geometry->chapter_payload_bits,
+ page_buffer,
+ geometry->bytes_per_page);
+}
+
+/* Validate a chapter index page read during rebuild. */
+int uds_validate_chapter_index_page(const struct delta_index_page *index_page,
+ const struct geometry *geometry)
+{
+ int result;
+ const struct delta_index *delta_index = &index_page->delta_index;
+ u32 first = index_page->lowest_list_number;
+ u32 last = index_page->highest_list_number;
+ u32 list_number;
+
+ /* We walk every delta list from start to finish. */
+ for (list_number = first; list_number <= last; list_number++) {
+ struct delta_index_entry entry;
+
+ result = uds_start_delta_index_search(delta_index, list_number - first, 0, &entry);
+ if (result != UDS_SUCCESS)
+ return result;
+
+ for (;;) {
+ result = uds_next_delta_index_entry(&entry);
+ if (result != UDS_SUCCESS)
+ /*
+ * A random bit stream is highly likely to arrive here when we go
+ * past the end of the delta list.
+ */
+ return result;
+
+ if (entry.at_end)
+ break;
+
+ /* Also make sure that the record page field contains a plausible value. */
+ if (uds_get_delta_entry_value(&entry) >=
+ geometry->record_pages_per_chapter)
+ /*
+ * Do not log this as an error. It happens in normal operation when
+ * we are doing a rebuild but haven't written the entire volume
+ * once.
+ */
+ return UDS_CORRUPT_DATA;
+ }
+ }
+ return UDS_SUCCESS;
+}
+
+/*
+ * Search a chapter index page for a record name, returning the record page number that may contain
+ * the name.
+ */
+int uds_search_chapter_index_page(struct delta_index_page *index_page,
+ const struct geometry *geometry,
+ const struct uds_record_name *name,
+ u16 *record_page_ptr)
+{
+ int result;
+ struct delta_index *delta_index = &index_page->delta_index;
+ u32 address = uds_hash_to_chapter_delta_address(name, geometry);
+ u32 delta_list_number = uds_hash_to_chapter_delta_list(name, geometry);
+ u32 sub_list_number = delta_list_number - index_page->lowest_list_number;
+ struct delta_index_entry entry;
+
+ result = uds_get_delta_index_entry(delta_index,
+ sub_list_number,
+ address,
+ name->name,
+ &entry);
+ if (result != UDS_SUCCESS)
+ return result;
+
+ if (was_entry_found(&entry, address))
+ *record_page_ptr = uds_get_delta_entry_value(&entry);
+ else
+ *record_page_ptr = NO_CHAPTER_INDEX_ENTRY;
+
+ return UDS_SUCCESS;
+}
new file mode 100644
@@ -0,0 +1,66 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#ifndef UDS_CHAPTER_INDEX_H
+#define UDS_CHAPTER_INDEX_H
+
+#include <linux/limits.h>
+
+#include "delta-index.h"
+#include "geometry.h"
+
+/*
+ * A chapter index for an open chapter is a mutable structure that tracks all the records that have
+ * been added to the chapter. A chapter index for a closed chapter is similar except that it is
+ * immutable because the contents of a closed chapter can never change, and the immutable structure
+ * is more efficient. Both types of chapter index are implemented with a delta index.
+ */
+
+enum {
+ /* The value returned when no entry is found in the chapter index. */
+ NO_CHAPTER_INDEX_ENTRY = U16_MAX,
+};
+
+struct open_chapter_index {
+ const struct geometry *geometry;
+ struct delta_index delta_index;
+ u64 virtual_chapter_number;
+ u64 volume_nonce;
+ size_t memory_size;
+};
+
+int __must_check uds_make_open_chapter_index(struct open_chapter_index **chapter_index,
+ const struct geometry *geometry,
+ u64 volume_nonce);
+
+void uds_free_open_chapter_index(struct open_chapter_index *chapter_index);
+
+void uds_empty_open_chapter_index(struct open_chapter_index *chapter_index,
+ u64 virtual_chapter_number);
+
+int __must_check uds_put_open_chapter_index_record(struct open_chapter_index *chapter_index,
+ const struct uds_record_name *name,
+ u32 page_number);
+
+int __must_check uds_pack_open_chapter_index_page(struct open_chapter_index *chapter_index,
+ u8 *memory,
+ u32 first_list,
+ bool last_page,
+ u32 *lists_packed);
+
+int __must_check uds_initialize_chapter_index_page(struct delta_index_page *index_page,
+ const struct geometry *geometry,
+ u8 *page_buffer,
+ u64 volume_nonce);
+
+int __must_check uds_validate_chapter_index_page(const struct delta_index_page *index_page,
+ const struct geometry *geometry);
+
+int __must_check uds_search_chapter_index_page(struct delta_index_page *index_page,
+ const struct geometry *geometry,
+ const struct uds_record_name *name,
+ u16 *record_page_ptr);
+
+#endif /* UDS_CHAPTER_INDEX_H */
new file mode 100644
@@ -0,0 +1,433 @@
+// SPDX-License-Identifier: GPL-2.0-only
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#include "open-chapter.h"
+
+#include <linux/log2.h>
+
+#include "config.h"
+#include "hash-utils.h"
+#include "logger.h"
+#include "memory-alloc.h"
+#include "numeric.h"
+#include "permassert.h"
+
+/*
+ * Each index zone has a dedicated open chapter zone structure which gets an equal share of the
+ * open chapter space. Records are assigned to zones based on their record name. Within each zone,
+ * records are stored in an array in the order they arrive. Additionally, a reference to each
+ * record is stored in a hash table to help determine if a new record duplicates an existing one.
+ * If new metadata for an existing name arrives, the record is altered in place. The array of
+ * records is 1-based so that record number 0 can be used to indicate an unused hash slot.
+ *
+ * Deleted records are marked with a flag rather than actually removed to simplify hash table
+ * management. The array of deleted flags overlays the array of hash slots, but the flags are
+ * indexed by record number instead of by record name. The number of hash slots will always be a
+ * power of two that is greater than the number of records to be indexed, guaranteeing that hash
+ * insertion cannot fail, and that there are sufficient flags for all records.
+ *
+ * Once any open chapter zone fills its available space, the chapter is closed. The records from
+ * each zone are interleaved to attempt to preserve temporal locality and assigned to record pages.
+ * Empty or deleted records are replaced by copies of a valid record so that the record pages only
+ * contain valid records. The chapter then constructs a delta index which maps each record name to
+ * the record page on which that record can be found, which is split into index pages. These
+ * structures are then passed to the volume to be recorded on storage.
+ *
+ * When the index is saved, the open chapter records are saved in a single array, once again
+ * interleaved to attempt to preserve temporal locality. When the index is reloaded, there may be a
+ * different number of zones than previously, so the records must be parcelled out to their new
+ * zones. In addition, depending on the distribution of record names, a new zone may have more
+ * records than it has space. In this case, the latest records for that zone will be discarded.
+ */
+
+static const u8 OPEN_CHAPTER_MAGIC[] = "ALBOC";
+static const u8 OPEN_CHAPTER_VERSION[] = "02.00";
+
+enum {
+ OPEN_CHAPTER_MAGIC_LENGTH = sizeof(OPEN_CHAPTER_MAGIC) - 1,
+ OPEN_CHAPTER_VERSION_LENGTH = sizeof(OPEN_CHAPTER_VERSION) - 1,
+ LOAD_RATIO = 2,
+};
+
+static inline size_t records_size(const struct open_chapter_zone *open_chapter)
+{
+ return sizeof(struct uds_volume_record) * (1 + open_chapter->capacity);
+}
+
+static inline size_t slots_size(size_t slot_count)
+{
+ return sizeof(struct open_chapter_zone_slot) * slot_count;
+}
+
+int uds_make_open_chapter(const struct geometry *geometry,
+ unsigned int zone_count,
+ struct open_chapter_zone **open_chapter_ptr)
+{
+ int result;
+ struct open_chapter_zone *open_chapter;
+ size_t capacity = geometry->records_per_chapter / zone_count;
+ size_t slot_count = (1 << bits_per(capacity * LOAD_RATIO));
+
+ result = UDS_ALLOCATE_EXTENDED(struct open_chapter_zone,
+ slot_count,
+ struct open_chapter_zone_slot,
+ "open chapter",
+ &open_chapter);
+ if (result != UDS_SUCCESS)
+ return result;
+
+ open_chapter->slot_count = slot_count;
+ open_chapter->capacity = capacity;
+ result = uds_allocate_cache_aligned(records_size(open_chapter),
+ "record pages",
+ &open_chapter->records);
+ if (result != UDS_SUCCESS) {
+ uds_free_open_chapter(open_chapter);
+ return result;
+ }
+
+ *open_chapter_ptr = open_chapter;
+ return UDS_SUCCESS;
+}
+
+void uds_reset_open_chapter(struct open_chapter_zone *open_chapter)
+{
+ open_chapter->size = 0;
+ open_chapter->deletions = 0;
+
+ memset(open_chapter->records, 0, records_size(open_chapter));
+ memset(open_chapter->slots, 0, slots_size(open_chapter->slot_count));
+}
+
+static unsigned int
+probe_chapter_slots(struct open_chapter_zone *open_chapter, const struct uds_record_name *name)
+{
+ struct uds_volume_record *record;
+ unsigned int slot_count = open_chapter->slot_count;
+ unsigned int slot = uds_name_to_hash_slot(name, slot_count);
+ unsigned int record_number;
+ unsigned int attempts = 1;
+
+ while (true) {
+ record_number = open_chapter->slots[slot].record_number;
+
+ /*
+ * If the hash slot is empty, we've reached the end of a chain without finding the
+ * record and should terminate the search.
+ */
+ if (record_number == 0)
+ return slot;
+
+ /*
+ * If the name of the record referenced by the slot matches and has not been
+ * deleted, then we've found the requested name.
+ */
+ record = &open_chapter->records[record_number];
+ if ((memcmp(&record->name, name, UDS_RECORD_NAME_SIZE) == 0) &&
+ !open_chapter->slots[record_number].deleted)
+ return slot;
+
+ /*
+ * Quadratic probing: advance the probe by 1, 2, 3, etc. and try again. This
+ * performs better than linear probing and works best for 2^N slots.
+ */
+ slot = (slot + attempts++) % slot_count;
+ }
+}
+
+void uds_search_open_chapter(struct open_chapter_zone *open_chapter,
+ const struct uds_record_name *name,
+ struct uds_record_data *metadata,
+ bool *found)
+{
+ unsigned int slot;
+ unsigned int record_number;
+
+ slot = probe_chapter_slots(open_chapter, name);
+ record_number = open_chapter->slots[slot].record_number;
+ if (record_number == 0) {
+ *found = false;
+ } else {
+ *found = true;
+ *metadata = open_chapter->records[record_number].data;
+ }
+}
+
+/* Add a record to the open chapter zone and return the remaining space. */
+int uds_put_open_chapter(struct open_chapter_zone *open_chapter,
+ const struct uds_record_name *name,
+ const struct uds_record_data *metadata)
+{
+ unsigned int slot;
+ unsigned int record_number;
+ struct uds_volume_record *record;
+
+ if (open_chapter->size >= open_chapter->capacity)
+ return 0;
+
+ slot = probe_chapter_slots(open_chapter, name);
+ record_number = open_chapter->slots[slot].record_number;
+
+ if (record_number == 0) {
+ record_number = ++open_chapter->size;
+ open_chapter->slots[slot].record_number = record_number;
+ }
+
+ record = &open_chapter->records[record_number];
+ record->name = *name;
+ record->data = *metadata;
+
+ return open_chapter->capacity - open_chapter->size;
+}
+
+void uds_remove_from_open_chapter(struct open_chapter_zone *open_chapter,
+ const struct uds_record_name *name)
+{
+ unsigned int slot;
+ unsigned int record_number;
+
+ slot = probe_chapter_slots(open_chapter, name);
+ record_number = open_chapter->slots[slot].record_number;
+
+ if (record_number > 0) {
+ open_chapter->slots[record_number].deleted = true;
+ open_chapter->deletions += 1;
+ }
+}
+
+void uds_free_open_chapter(struct open_chapter_zone *open_chapter)
+{
+ if (open_chapter != NULL) {
+ UDS_FREE(open_chapter->records);
+ UDS_FREE(open_chapter);
+ }
+}
+
+/* Map each record name to its record page number in the delta chapter index. */
+static int fill_delta_chapter_index(struct open_chapter_zone **chapter_zones,
+ unsigned int zone_count,
+ struct open_chapter_index *index,
+ struct uds_volume_record *collated_records)
+{
+ int result;
+ unsigned int records_per_chapter;
+ unsigned int records_per_page;
+ unsigned int record_index;
+ unsigned int records = 0;
+ u32 page_number;
+ unsigned int z;
+ int overflow_count = 0;
+ struct uds_volume_record *fill_record = NULL;
+
+ /*
+ * The record pages should not have any empty space, so find a record with which to fill
+ * the chapter zone if it was closed early, and also to replace any deleted records. The
+ * last record in any filled zone is guaranteed to not have been deleted, so use one of
+ * those.
+ */
+ for (z = 0; z < zone_count; z++) {
+ struct open_chapter_zone *zone = chapter_zones[z];
+
+ if (zone->size == zone->capacity) {
+ fill_record = &zone->records[zone->size];
+ break;
+ }
+ }
+
+ records_per_chapter = index->geometry->records_per_chapter;
+ records_per_page = index->geometry->records_per_page;
+
+ for (records = 0; records < records_per_chapter; records++) {
+ struct uds_volume_record *record = &collated_records[records];
+ struct open_chapter_zone *open_chapter;
+
+ /* The record arrays in the zones are 1-based. */
+ record_index = 1 + (records / zone_count);
+ page_number = records / records_per_page;
+ open_chapter = chapter_zones[records % zone_count];
+
+ /* Use the fill record in place of an unused record. */
+ if (record_index > open_chapter->size ||
+ open_chapter->slots[record_index].deleted) {
+ *record = *fill_record;
+ continue;
+ }
+
+ *record = open_chapter->records[record_index];
+ result = uds_put_open_chapter_index_record(index, &record->name, page_number);
+ switch (result) {
+ case UDS_SUCCESS:
+ break;
+ case UDS_OVERFLOW:
+ overflow_count++;
+ break;
+ default:
+ uds_log_error_strerror(result, "failed to build open chapter index");
+ return result;
+ }
+ }
+
+ if (overflow_count > 0)
+ uds_log_warning("Failed to add %d entries to chapter index", overflow_count);
+
+ return UDS_SUCCESS;
+}
+
+int uds_close_open_chapter(struct open_chapter_zone **chapter_zones,
+ unsigned int zone_count,
+ struct volume *volume,
+ struct open_chapter_index *chapter_index,
+ struct uds_volume_record *collated_records,
+ u64 virtual_chapter_number)
+{
+ int result;
+
+ uds_empty_open_chapter_index(chapter_index, virtual_chapter_number);
+ result = fill_delta_chapter_index(chapter_zones,
+ zone_count,
+ chapter_index,
+ collated_records);
+ if (result != UDS_SUCCESS)
+ return result;
+
+ return uds_write_chapter(volume, chapter_index, collated_records);
+}
+
+int uds_save_open_chapter(struct uds_index *index, struct buffered_writer *writer)
+{
+ int result;
+ struct open_chapter_zone *open_chapter;
+ struct uds_volume_record *record;
+ u8 record_count_data[sizeof(u32)];
+ u32 record_count = 0;
+ unsigned int record_index;
+ unsigned int z;
+
+ result = uds_write_to_buffered_writer(writer,
+ OPEN_CHAPTER_MAGIC,
+ OPEN_CHAPTER_MAGIC_LENGTH);
+ if (result != UDS_SUCCESS)
+ return result;
+
+ result = uds_write_to_buffered_writer(writer,
+ OPEN_CHAPTER_VERSION,
+ OPEN_CHAPTER_VERSION_LENGTH);
+ if (result != UDS_SUCCESS)
+ return result;
+
+ for (z = 0; z < index->zone_count; z++) {
+ open_chapter = index->zones[z]->open_chapter;
+ record_count += open_chapter->size - open_chapter->deletions;
+ }
+
+ put_unaligned_le32(record_count, record_count_data);
+ result = uds_write_to_buffered_writer(writer,
+ record_count_data,
+ sizeof(record_count_data));
+ if (result != UDS_SUCCESS)
+ return result;
+
+ record_index = 1;
+ while (record_count > 0) {
+ for (z = 0; z < index->zone_count; z++) {
+ open_chapter = index->zones[z]->open_chapter;
+ if (record_index > open_chapter->size)
+ continue;
+
+ if (open_chapter->slots[record_index].deleted)
+ continue;
+
+ record = &open_chapter->records[record_index];
+ result = uds_write_to_buffered_writer(writer,
+ (u8 *) record,
+ sizeof(*record));
+ if (result != UDS_SUCCESS)
+ return result;
+
+ record_count--;
+ }
+
+ record_index++;
+ }
+
+ return uds_flush_buffered_writer(writer);
+}
+
+u64 uds_compute_saved_open_chapter_size(struct geometry *geometry)
+{
+ unsigned int records_per_chapter = geometry->records_per_chapter;
+
+ return OPEN_CHAPTER_MAGIC_LENGTH + OPEN_CHAPTER_VERSION_LENGTH + sizeof(u32) +
+ records_per_chapter * sizeof(struct uds_volume_record);
+}
+
+static int load_version20(struct uds_index *index, struct buffered_reader *reader)
+{
+ int result;
+ u32 record_count;
+ u8 record_count_data[sizeof(u32)];
+ struct uds_volume_record record;
+
+ /*
+ * Track which zones cannot accept any more records. If the open chapter had a different
+ * number of zones previously, some new zones may have more records than they have space
+ * for. These overflow records will be discarded.
+ */
+ bool full_flags[MAX_ZONES] = {
+ false,
+ };
+
+ result = uds_read_from_buffered_reader(reader,
+ (u8 *) &record_count_data,
+ sizeof(record_count_data));
+ if (result != UDS_SUCCESS)
+ return result;
+
+ record_count = get_unaligned_le32(record_count_data);
+ while (record_count-- > 0) {
+ unsigned int zone = 0;
+
+ result = uds_read_from_buffered_reader(reader, (u8 *) &record, sizeof(record));
+ if (result != UDS_SUCCESS)
+ return result;
+
+ if (index->zone_count > 1)
+ zone = uds_get_volume_index_zone(index->volume_index, &record.name);
+
+ if (!full_flags[zone]) {
+ struct open_chapter_zone *open_chapter;
+ unsigned int remaining;
+
+ open_chapter = index->zones[zone]->open_chapter;
+ remaining = uds_put_open_chapter(open_chapter, &record.name, &record.data);
+ /* Do not allow any zone to fill completely. */
+ full_flags[zone] = (remaining <= 1);
+ }
+ }
+
+ return UDS_SUCCESS;
+}
+
+int uds_load_open_chapter(struct uds_index *index, struct buffered_reader *reader)
+{
+ u8 version[OPEN_CHAPTER_VERSION_LENGTH];
+ int result;
+
+ result = uds_verify_buffered_data(reader, OPEN_CHAPTER_MAGIC, OPEN_CHAPTER_MAGIC_LENGTH);
+ if (result != UDS_SUCCESS)
+ return result;
+
+ result = uds_read_from_buffered_reader(reader, version, sizeof(version));
+ if (result != UDS_SUCCESS)
+ return result;
+
+ if (memcmp(OPEN_CHAPTER_VERSION, version, sizeof(version)) != 0)
+ return uds_log_error_strerror(UDS_CORRUPT_DATA,
+ "Invalid open chapter version: %.*s",
+ (int) sizeof(version),
+ version);
+
+ return load_version20(index, reader);
+}
new file mode 100644
@@ -0,0 +1,79 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * Copyright 2023 Red Hat
+ */
+
+#ifndef UDS_OPEN_CHAPTER_H
+#define UDS_OPEN_CHAPTER_H
+
+#include "chapter-index.h"
+#include "geometry.h"
+#include "index.h"
+#include "volume.h"
+
+/*
+ * The open chapter tracks the newest records in memory. Like the index as a whole, each open
+ * chapter is divided into a number of independent zones which are interleaved when the chapter is
+ * committed to the volume.
+ */
+
+enum {
+ OPEN_CHAPTER_RECORD_NUMBER_BITS = 23,
+};
+
+struct open_chapter_zone_slot {
+ /* If non-zero, the record number addressed by this hash slot */
+ unsigned int record_number : OPEN_CHAPTER_RECORD_NUMBER_BITS;
+ /* If true, the record at the index of this hash slot was deleted */
+ bool deleted : 1;
+} __packed;
+
+struct open_chapter_zone {
+ /* The maximum number of records that can be stored */
+ unsigned int capacity;
+ /* The number of records stored */
+ unsigned int size;
+ /* The number of deleted records */
+ unsigned int deletions;
+ /* Array of chunk records, 1-based */
+ struct uds_volume_record *records;
+ /* The number of slots in the hash table */
+ unsigned int slot_count;
+ /* The hash table slots, referencing virtual record numbers */
+ struct open_chapter_zone_slot slots[];
+};
+
+int __must_check uds_make_open_chapter(const struct geometry *geometry,
+ unsigned int zone_count,
+ struct open_chapter_zone **open_chapter_ptr);
+
+void uds_reset_open_chapter(struct open_chapter_zone *open_chapter);
+
+void uds_search_open_chapter(struct open_chapter_zone *open_chapter,
+ const struct uds_record_name *name,
+ struct uds_record_data *metadata,
+ bool *found);
+
+int __must_check uds_put_open_chapter(struct open_chapter_zone *open_chapter,
+ const struct uds_record_name *name,
+ const struct uds_record_data *metadata);
+
+void uds_remove_from_open_chapter(struct open_chapter_zone *open_chapter,
+ const struct uds_record_name *name);
+
+void uds_free_open_chapter(struct open_chapter_zone *open_chapter);
+
+int __must_check uds_close_open_chapter(struct open_chapter_zone **chapter_zones,
+ unsigned int zone_count,
+ struct volume *volume,
+ struct open_chapter_index *chapter_index,
+ struct uds_volume_record *collated_records,
+ u64 virtual_chapter_number);
+
+int __must_check uds_save_open_chapter(struct uds_index *index, struct buffered_writer *writer);
+
+int __must_check uds_load_open_chapter(struct uds_index *index, struct buffered_reader *reader);
+
+u64 uds_compute_saved_open_chapter_size(struct geometry *geometry);
+
+#endif /* UDS_OPEN_CHAPTER_H */