Author | Tokens | Token Proportion | Commits | Commit Proportion |
---|---|---|---|---|
Matthew Sakai | 9065 | 99.02% | 3 | 30.00% |
Mike Snitzer | 60 | 0.66% | 6 | 60.00% |
Bruce Johnston | 30 | 0.33% | 1 | 10.00% |
Total | 9155 | 10 |
// SPDX-License-Identifier: GPL-2.0-only /* * Copyright 2023 Red Hat */ #include "delta-index.h" #include <linux/bitops.h> #include <linux/bits.h> #include <linux/compiler.h> #include <linux/limits.h> #include <linux/log2.h> #include "cpu.h" #include "errors.h" #include "logger.h" #include "memory-alloc.h" #include "numeric.h" #include "permassert.h" #include "string-utils.h" #include "time-utils.h" #include "config.h" #include "indexer.h" /* * The entries in a delta index could be stored in a single delta list, but to reduce search times * and update costs it uses multiple delta lists. These lists are stored in a single chunk of * memory managed by the delta_zone structure. The delta_zone can move the data around within its * memory, so the location of each delta list is recorded as a bit offset into the memory. Because * the volume index can contain over a million delta lists, we want to be efficient with the size * of the delta list header information. This information is encoded into 16 bytes per list. The * volume index delta list memory can easily exceed 4 gigabits, so a 64 bit value is needed to * address the memory. The volume index delta lists average around 6 kilobits, so 16 bits are * sufficient to store the size of a delta list. * * Each delta list is stored as a bit stream. Within the delta list encoding, bits and bytes are * numbered in little endian order. Within a byte, bit 0 is the least significant bit (0x1), and * bit 7 is the most significant bit (0x80). Within a bit stream, bit 7 is the most significant bit * of byte 0, and bit 8 is the least significant bit of byte 1. Within a byte array, a byte's * number corresponds to its index in the array. * * A standard delta list entry is stored as a fixed length payload (the value) followed by a * variable length key (the delta). A collision entry is used when two block names have the same * delta list address. A collision entry always follows a standard entry for the hash with which it * collides, and is encoded with DELTA == 0 with an additional 256 bits field at the end, * containing the full block name. An entry with a delta of 0 at the beginning of a delta list * indicates a normal entry. * * The delta in each entry is encoded with a variable-length Huffman code to minimize the memory * used by small deltas. The Huffman code is specified by three parameters, which can be computed * from the desired mean delta when the index is full. (See compute_coding_constants() for * details.) * * The bit field utilities used to read and write delta entries assume that it is possible to read * some bytes beyond the end of the bit field, so a delta_zone memory allocation is guarded by two * invalid delta lists to prevent reading outside the delta_zone memory. The valid delta lists are * numbered 1 to N, and the guard lists are numbered 0 and N+1. The function to decode the bit * stream include a step that skips over bits set to 0 until the first 1 bit is found. A corrupted * delta list could cause this step to run off the end of the delta_zone memory, so as extra * protection against this happening, the tail guard list is set to all ones. * * The delta_index supports two different forms. The mutable form is created by * uds_initialize_delta_index(), and is used for the volume index and for open chapter indexes. The * immutable form is created by uds_initialize_delta_index_page(), and is used for closed (and * cached) chapter index pages. The immutable form does not allocate delta list headers or * temporary offsets, and thus is somewhat more memory efficient. */ /* * This is the largest field size supported by get_field() and set_field(). Any field that is * larger is not guaranteed to fit in a single byte-aligned u32. */ #define MAX_FIELD_BITS ((sizeof(u32) - 1) * BITS_PER_BYTE + 1) /* * This is the largest field size supported by get_big_field() and set_big_field(). Any field that * is larger is not guaranteed to fit in a single byte-aligned u64. */ #define MAX_BIG_FIELD_BITS ((sizeof(u64) - 1) * BITS_PER_BYTE + 1) /* * This is the number of guard bytes needed at the end of the memory byte array when using the bit * utilities. These utilities call get_big_field() and set_big_field(), which can access up to 7 * bytes beyond the end of the desired field. The definition is written to make it clear how this * value is derived. */ #define POST_FIELD_GUARD_BYTES (sizeof(u64) - 1) /* The number of guard bits that are needed in the tail guard list */ #define GUARD_BITS (POST_FIELD_GUARD_BYTES * BITS_PER_BYTE) /* * The maximum size of a single delta list in bytes. We count guard bytes in this value because a * buffer of this size can be used with move_bits(). */ #define DELTA_LIST_MAX_BYTE_COUNT \ ((U16_MAX + BITS_PER_BYTE) / BITS_PER_BYTE + POST_FIELD_GUARD_BYTES) /* The number of extra bytes and bits needed to store a collision entry */ #define COLLISION_BYTES UDS_RECORD_NAME_SIZE #define COLLISION_BITS (COLLISION_BYTES * BITS_PER_BYTE) /* * Immutable delta lists are packed into pages containing a header that encodes the delta list * information into 19 bits per list (64KB bit offset). */ #define IMMUTABLE_HEADER_SIZE 19 /* * Constants and structures for the saved delta index. "DI" is for delta_index, and -##### is a * number to increment when the format of the data changes. */ #define MAGIC_SIZE 8 static const char DELTA_INDEX_MAGIC[] = "DI-00002"; struct delta_index_header { char magic[MAGIC_SIZE]; u32 zone_number; u32 zone_count; u32 first_list; u32 list_count; u64 record_count; u64 collision_count; }; /* * Header data used for immutable delta index pages. This data is followed by the delta list offset * table. */ struct delta_page_header { /* Externally-defined nonce */ u64 nonce; /* The virtual chapter number */ u64 virtual_chapter_number; /* Index of the first delta list on the page */ u16 first_list; /* Number of delta lists on the page */ u16 list_count; } __packed; static inline u64 get_delta_list_byte_start(const struct delta_list *delta_list) { return delta_list->start / BITS_PER_BYTE; } static inline u16 get_delta_list_byte_size(const struct delta_list *delta_list) { unsigned int bit_offset = delta_list->start % BITS_PER_BYTE; return BITS_TO_BYTES(bit_offset + delta_list->size); } static void rebalance_delta_zone(const struct delta_zone *delta_zone, u32 first, u32 last) { struct delta_list *delta_list; u64 new_start; if (first == last) { /* Only one list is moving, and we know there is space. */ delta_list = &delta_zone->delta_lists[first]; new_start = delta_zone->new_offsets[first]; if (delta_list->start != new_start) { u64 source; u64 destination; source = get_delta_list_byte_start(delta_list); delta_list->start = new_start; destination = get_delta_list_byte_start(delta_list); memmove(delta_zone->memory + destination, delta_zone->memory + source, get_delta_list_byte_size(delta_list)); } } else { /* * There is more than one list. Divide the problem in half, and use recursive calls * to process each half. Note that after this computation, first <= middle, and * middle < last. */ u32 middle = (first + last) / 2; delta_list = &delta_zone->delta_lists[middle]; new_start = delta_zone->new_offsets[middle]; /* * The direction that our middle list is moving determines which half of the * problem must be processed first. */ if (new_start > delta_list->start) { rebalance_delta_zone(delta_zone, middle + 1, last); rebalance_delta_zone(delta_zone, first, middle); } else { rebalance_delta_zone(delta_zone, first, middle); rebalance_delta_zone(delta_zone, middle + 1, last); } } } static inline size_t get_zone_memory_size(unsigned int zone_count, size_t memory_size) { /* Round up so that each zone is a multiple of 64K in size. */ size_t ALLOC_BOUNDARY = 64 * 1024; return (memory_size / zone_count + ALLOC_BOUNDARY - 1) & -ALLOC_BOUNDARY; } void uds_reset_delta_index(const struct delta_index *delta_index) { unsigned int z; /* * Initialize all delta lists to be empty. We keep 2 extra delta list descriptors, one * before the first real entry and one after so that we don't need to bounds check the * array access when calculating preceding and following gap sizes. */ for (z = 0; z < delta_index->zone_count; z++) { u64 list_bits; u64 spacing; u64 offset; unsigned int i; struct delta_zone *zone = &delta_index->delta_zones[z]; struct delta_list *delta_lists = zone->delta_lists; /* Zeroing the delta list headers initializes the head guard list correctly. */ memset(delta_lists, 0, (zone->list_count + 2) * sizeof(struct delta_list)); /* Set all the bits in the end guard list. */ list_bits = (u64) zone->size * BITS_PER_BYTE - GUARD_BITS; delta_lists[zone->list_count + 1].start = list_bits; delta_lists[zone->list_count + 1].size = GUARD_BITS; memset(zone->memory + (list_bits / BITS_PER_BYTE), ~0, POST_FIELD_GUARD_BYTES); /* Evenly space out the real delta lists by setting regular offsets. */ spacing = list_bits / zone->list_count; offset = spacing / 2; for (i = 1; i <= zone->list_count; i++) { delta_lists[i].start = offset; offset += spacing; } /* Update the statistics. */ zone->discard_count += zone->record_count; zone->record_count = 0; zone->collision_count = 0; } } /* Compute the Huffman coding parameters for the given mean delta. The Huffman code is specified by * three parameters: * * MINBITS The number of bits in the smallest code * BASE The number of values coded using a code of length MINBITS * INCR The number of values coded by using one additional bit * * These parameters are related by this equation: * * BASE + INCR == 1 << MINBITS * * The math for the Huffman code of an exponential distribution says that * * INCR = log(2) * MEAN_DELTA * * Then use the smallest MINBITS value so that * * (1 << MINBITS) > INCR * * And then * * BASE = (1 << MINBITS) - INCR * * Now the index can generate a code such that * - The first BASE values code using MINBITS bits. * - The next INCR values code using MINBITS+1 bits. * - The next INCR values code using MINBITS+2 bits. * - (and so on). */ static void compute_coding_constants(u32 mean_delta, u16 *min_bits, u32 *min_keys, u32 *incr_keys) { /* * We want to compute the rounded value of log(2) * mean_delta. Since we cannot always use * floating point, use a really good integer approximation. */ *incr_keys = (836158UL * mean_delta + 603160UL) / 1206321UL; *min_bits = bits_per(*incr_keys + 1); *min_keys = (1 << *min_bits) - *incr_keys; } void uds_uninitialize_delta_index(struct delta_index *delta_index) { unsigned int z; if (delta_index->delta_zones == NULL) return; for (z = 0; z < delta_index->zone_count; z++) { vdo_free(vdo_forget(delta_index->delta_zones[z].new_offsets)); vdo_free(vdo_forget(delta_index->delta_zones[z].delta_lists)); vdo_free(vdo_forget(delta_index->delta_zones[z].memory)); } vdo_free(delta_index->delta_zones); memset(delta_index, 0, sizeof(struct delta_index)); } static int initialize_delta_zone(struct delta_zone *delta_zone, size_t size, u32 first_list, u32 list_count, u32 mean_delta, u32 payload_bits, u8 tag) { int result; result = vdo_allocate(size, u8, "delta list", &delta_zone->memory); if (result != VDO_SUCCESS) return result; result = vdo_allocate(list_count + 2, u64, "delta list temp", &delta_zone->new_offsets); if (result != VDO_SUCCESS) return result; /* Allocate the delta lists. */ result = vdo_allocate(list_count + 2, struct delta_list, "delta lists", &delta_zone->delta_lists); if (result != VDO_SUCCESS) return result; compute_coding_constants(mean_delta, &delta_zone->min_bits, &delta_zone->min_keys, &delta_zone->incr_keys); delta_zone->value_bits = payload_bits; delta_zone->buffered_writer = NULL; delta_zone->size = size; delta_zone->rebalance_time = 0; delta_zone->rebalance_count = 0; delta_zone->record_count = 0; delta_zone->collision_count = 0; delta_zone->discard_count = 0; delta_zone->overflow_count = 0; delta_zone->first_list = first_list; delta_zone->list_count = list_count; delta_zone->tag = tag; return UDS_SUCCESS; } int uds_initialize_delta_index(struct delta_index *delta_index, unsigned int zone_count, u32 list_count, u32 mean_delta, u32 payload_bits, size_t memory_size, u8 tag) { int result; unsigned int z; size_t zone_memory; result = vdo_allocate(zone_count, struct delta_zone, "Delta Index Zones", &delta_index->delta_zones); if (result != VDO_SUCCESS) return result; delta_index->zone_count = zone_count; delta_index->list_count = list_count; delta_index->lists_per_zone = DIV_ROUND_UP(list_count, zone_count); delta_index->memory_size = 0; delta_index->mutable = true; delta_index->tag = tag; for (z = 0; z < zone_count; z++) { u32 lists_in_zone = delta_index->lists_per_zone; u32 first_list_in_zone = z * lists_in_zone; if (z == zone_count - 1) { /* * The last zone gets fewer lists if zone_count doesn't evenly divide * list_count. We'll have an underflow if the assertion below doesn't hold. */ if (delta_index->list_count <= first_list_in_zone) { uds_uninitialize_delta_index(delta_index); return vdo_log_error_strerror(UDS_INVALID_ARGUMENT, "%u delta lists not enough for %u zones", list_count, zone_count); } lists_in_zone = delta_index->list_count - first_list_in_zone; } zone_memory = get_zone_memory_size(zone_count, memory_size); result = initialize_delta_zone(&delta_index->delta_zones[z], zone_memory, first_list_in_zone, lists_in_zone, mean_delta, payload_bits, tag); if (result != UDS_SUCCESS) { uds_uninitialize_delta_index(delta_index); return result; } delta_index->memory_size += (sizeof(struct delta_zone) + zone_memory + (lists_in_zone + 2) * (sizeof(struct delta_list) + sizeof(u64))); } uds_reset_delta_index(delta_index); return UDS_SUCCESS; } /* Read a bit field from an arbitrary bit boundary. */ static inline u32 get_field(const u8 *memory, u64 offset, u8 size) { const void *addr = memory + offset / BITS_PER_BYTE; return (get_unaligned_le32(addr) >> (offset % BITS_PER_BYTE)) & ((1 << size) - 1); } /* Write a bit field to an arbitrary bit boundary. */ static inline void set_field(u32 value, u8 *memory, u64 offset, u8 size) { void *addr = memory + offset / BITS_PER_BYTE; int shift = offset % BITS_PER_BYTE; u32 data = get_unaligned_le32(addr); data &= ~(((1 << size) - 1) << shift); data |= value << shift; put_unaligned_le32(data, addr); } /* Get the bit offset to the immutable delta list header. */ static inline u32 get_immutable_header_offset(u32 list_number) { return sizeof(struct delta_page_header) * BITS_PER_BYTE + list_number * IMMUTABLE_HEADER_SIZE; } /* Get the bit offset to the start of the immutable delta list bit stream. */ static inline u32 get_immutable_start(const u8 *memory, u32 list_number) { return get_field(memory, get_immutable_header_offset(list_number), IMMUTABLE_HEADER_SIZE); } /* Set the bit offset to the start of the immutable delta list bit stream. */ static inline void set_immutable_start(u8 *memory, u32 list_number, u32 start) { set_field(start, memory, get_immutable_header_offset(list_number), IMMUTABLE_HEADER_SIZE); } static bool verify_delta_index_page(u64 nonce, u16 list_count, u64 expected_nonce, u8 *memory, size_t memory_size) { unsigned int i; /* * Verify the nonce. A mismatch can happen here during rebuild if we haven't written the * entire volume at least once. */ if (nonce != expected_nonce) return false; /* Verify that the number of delta lists can fit in the page. */ if (list_count > ((memory_size - sizeof(struct delta_page_header)) * BITS_PER_BYTE / IMMUTABLE_HEADER_SIZE)) return false; /* * Verify that the first delta list is immediately after the last delta * list header. */ if (get_immutable_start(memory, 0) != get_immutable_header_offset(list_count + 1)) return false; /* Verify that the lists are in the correct order. */ for (i = 0; i < list_count; i++) { if (get_immutable_start(memory, i) > get_immutable_start(memory, i + 1)) return false; } /* * Verify that the last list ends on the page, and that there is room * for the post-field guard bits. */ if (get_immutable_start(memory, list_count) > (memory_size - POST_FIELD_GUARD_BYTES) * BITS_PER_BYTE) return false; /* Verify that the guard bytes are correctly set to all ones. */ for (i = 0; i < POST_FIELD_GUARD_BYTES; i++) { if (memory[memory_size - POST_FIELD_GUARD_BYTES + i] != (u8) ~0) return false; } /* All verifications passed. */ return true; } /* Initialize a delta index page to refer to a supplied page. */ int uds_initialize_delta_index_page(struct delta_index_page *delta_index_page, u64 expected_nonce, u32 mean_delta, u32 payload_bits, u8 *memory, size_t memory_size) { u64 nonce; u64 vcn; u64 first_list; u64 list_count; struct delta_page_header *header = (struct delta_page_header *) memory; struct delta_zone *delta_zone = &delta_index_page->delta_zone; const u8 *nonce_addr = (const u8 *) &header->nonce; const u8 *vcn_addr = (const u8 *) &header->virtual_chapter_number; const u8 *first_list_addr = (const u8 *) &header->first_list; const u8 *list_count_addr = (const u8 *) &header->list_count; /* First assume that the header is little endian. */ nonce = get_unaligned_le64(nonce_addr); vcn = get_unaligned_le64(vcn_addr); first_list = get_unaligned_le16(first_list_addr); list_count = get_unaligned_le16(list_count_addr); if (!verify_delta_index_page(nonce, list_count, expected_nonce, memory, memory_size)) { /* If that fails, try big endian. */ nonce = get_unaligned_be64(nonce_addr); vcn = get_unaligned_be64(vcn_addr); first_list = get_unaligned_be16(first_list_addr); list_count = get_unaligned_be16(list_count_addr); if (!verify_delta_index_page(nonce, list_count, expected_nonce, memory, memory_size)) { /* * Both attempts failed. Do not log this as an error, because it can happen * during a rebuild if we haven't written the entire volume at least once. */ return UDS_CORRUPT_DATA; } } delta_index_page->delta_index.delta_zones = delta_zone; delta_index_page->delta_index.zone_count = 1; delta_index_page->delta_index.list_count = list_count; delta_index_page->delta_index.lists_per_zone = list_count; delta_index_page->delta_index.mutable = false; delta_index_page->delta_index.tag = 'p'; delta_index_page->virtual_chapter_number = vcn; delta_index_page->lowest_list_number = first_list; delta_index_page->highest_list_number = first_list + list_count - 1; compute_coding_constants(mean_delta, &delta_zone->min_bits, &delta_zone->min_keys, &delta_zone->incr_keys); delta_zone->value_bits = payload_bits; delta_zone->memory = memory; delta_zone->delta_lists = NULL; delta_zone->new_offsets = NULL; delta_zone->buffered_writer = NULL; delta_zone->size = memory_size; delta_zone->rebalance_time = 0; delta_zone->rebalance_count = 0; delta_zone->record_count = 0; delta_zone->collision_count = 0; delta_zone->discard_count = 0; delta_zone->overflow_count = 0; delta_zone->first_list = 0; delta_zone->list_count = list_count; delta_zone->tag = 'p'; return UDS_SUCCESS; } /* Read a large bit field from an arbitrary bit boundary. */ static inline u64 get_big_field(const u8 *memory, u64 offset, u8 size) { const void *addr = memory + offset / BITS_PER_BYTE; return (get_unaligned_le64(addr) >> (offset % BITS_PER_BYTE)) & ((1UL << size) - 1); } /* Write a large bit field to an arbitrary bit boundary. */ static inline void set_big_field(u64 value, u8 *memory, u64 offset, u8 size) { void *addr = memory + offset / BITS_PER_BYTE; u8 shift = offset % BITS_PER_BYTE; u64 data = get_unaligned_le64(addr); data &= ~(((1UL << size) - 1) << shift); data |= value << shift; put_unaligned_le64(data, addr); } /* Set a sequence of bits to all zeros. */ static inline void set_zero(u8 *memory, u64 offset, u32 size) { if (size > 0) { u8 *addr = memory + offset / BITS_PER_BYTE; u8 shift = offset % BITS_PER_BYTE; u32 count = size + shift > BITS_PER_BYTE ? (u32) BITS_PER_BYTE - shift : size; *addr++ &= ~(((1 << count) - 1) << shift); for (size -= count; size > BITS_PER_BYTE; size -= BITS_PER_BYTE) *addr++ = 0; if (size > 0) *addr &= 0xFF << size; } } /* * Move several bits from a higher to a lower address, moving the lower addressed bits first. The * size and memory offsets are measured in bits. */ static void move_bits_down(const u8 *from, u64 from_offset, u8 *to, u64 to_offset, u32 size) { const u8 *source; u8 *destination; u8 offset; u8 count; u64 field; /* Start by moving one field that ends on a to int boundary. */ count = (MAX_BIG_FIELD_BITS - ((to_offset + MAX_BIG_FIELD_BITS) % BITS_PER_TYPE(u32))); field = get_big_field(from, from_offset, count); set_big_field(field, to, to_offset, count); from_offset += count; to_offset += count; size -= count; /* Now do the main loop to copy 32 bit chunks that are int-aligned at the destination. */ offset = from_offset % BITS_PER_TYPE(u32); source = from + (from_offset - offset) / BITS_PER_BYTE; destination = to + to_offset / BITS_PER_BYTE; while (size > MAX_BIG_FIELD_BITS) { put_unaligned_le32(get_unaligned_le64(source) >> offset, destination); source += sizeof(u32); destination += sizeof(u32); from_offset += BITS_PER_TYPE(u32); to_offset += BITS_PER_TYPE(u32); size -= BITS_PER_TYPE(u32); } /* Finish up by moving any remaining bits. */ if (size > 0) { field = get_big_field(from, from_offset, size); set_big_field(field, to, to_offset, size); } } /* * Move several bits from a lower to a higher address, moving the higher addressed bits first. The * size and memory offsets are measured in bits. */ static void move_bits_up(const u8 *from, u64 from_offset, u8 *to, u64 to_offset, u32 size) { const u8 *source; u8 *destination; u8 offset; u8 count; u64 field; /* Start by moving one field that begins on a destination int boundary. */ count = (to_offset + size) % BITS_PER_TYPE(u32); if (count > 0) { size -= count; field = get_big_field(from, from_offset + size, count); set_big_field(field, to, to_offset + size, count); } /* Now do the main loop to copy 32 bit chunks that are int-aligned at the destination. */ offset = (from_offset + size) % BITS_PER_TYPE(u32); source = from + (from_offset + size - offset) / BITS_PER_BYTE; destination = to + (to_offset + size) / BITS_PER_BYTE; while (size > MAX_BIG_FIELD_BITS) { source -= sizeof(u32); destination -= sizeof(u32); size -= BITS_PER_TYPE(u32); put_unaligned_le32(get_unaligned_le64(source) >> offset, destination); } /* Finish up by moving any remaining bits. */ if (size > 0) { field = get_big_field(from, from_offset, size); set_big_field(field, to, to_offset, size); } } /* * Move bits from one field to another. When the fields overlap, behave as if we first move all the * bits from the source to a temporary value, and then move all the bits from the temporary value * to the destination. The size and memory offsets are measured in bits. */ static void move_bits(const u8 *from, u64 from_offset, u8 *to, u64 to_offset, u32 size) { u64 field; /* A small move doesn't require special handling. */ if (size <= MAX_BIG_FIELD_BITS) { if (size > 0) { field = get_big_field(from, from_offset, size); set_big_field(field, to, to_offset, size); } return; } if (from_offset > to_offset) move_bits_down(from, from_offset, to, to_offset, size); else move_bits_up(from, from_offset, to, to_offset, size); } /* * Pack delta lists from a mutable delta index into an immutable delta index page. A range of delta * lists (starting with a specified list index) is copied from the mutable delta index into a * memory page used in the immutable index. The number of lists copied onto the page is returned in * list_count. */ int uds_pack_delta_index_page(const struct delta_index *delta_index, u64 header_nonce, u8 *memory, size_t memory_size, u64 virtual_chapter_number, u32 first_list, u32 *list_count) { const struct delta_zone *delta_zone; struct delta_list *delta_lists; u32 max_lists; u32 n_lists = 0; u32 offset; u32 i; int free_bits; int bits; struct delta_page_header *header; delta_zone = &delta_index->delta_zones[0]; delta_lists = &delta_zone->delta_lists[first_list + 1]; max_lists = delta_index->list_count - first_list; /* * Compute how many lists will fit on the page. Subtract the size of the fixed header, one * delta list offset, and the guard bytes from the page size to determine how much space is * available for delta lists. */ free_bits = memory_size * BITS_PER_BYTE; free_bits -= get_immutable_header_offset(1); free_bits -= GUARD_BITS; if (free_bits < IMMUTABLE_HEADER_SIZE) { /* This page is too small to store any delta lists. */ return vdo_log_error_strerror(UDS_OVERFLOW, "Chapter Index Page of %zu bytes is too small", memory_size); } while (n_lists < max_lists) { /* Each list requires a delta list offset and the list data. */ bits = IMMUTABLE_HEADER_SIZE + delta_lists[n_lists].size; if (bits > free_bits) break; n_lists++; free_bits -= bits; } *list_count = n_lists; header = (struct delta_page_header *) memory; put_unaligned_le64(header_nonce, (u8 *) &header->nonce); put_unaligned_le64(virtual_chapter_number, (u8 *) &header->virtual_chapter_number); put_unaligned_le16(first_list, (u8 *) &header->first_list); put_unaligned_le16(n_lists, (u8 *) &header->list_count); /* Construct the delta list offset table. */ offset = get_immutable_header_offset(n_lists + 1); set_immutable_start(memory, 0, offset); for (i = 0; i < n_lists; i++) { offset += delta_lists[i].size; set_immutable_start(memory, i + 1, offset); } /* Copy the delta list data onto the memory page. */ for (i = 0; i < n_lists; i++) { move_bits(delta_zone->memory, delta_lists[i].start, memory, get_immutable_start(memory, i), delta_lists[i].size); } /* Set all the bits in the guard bytes. */ memset(memory + memory_size - POST_FIELD_GUARD_BYTES, ~0, POST_FIELD_GUARD_BYTES); return UDS_SUCCESS; } /* Compute the new offsets of the delta lists. */ static void compute_new_list_offsets(struct delta_zone *delta_zone, u32 growing_index, size_t growing_size, size_t used_space) { size_t spacing; u32 i; struct delta_list *delta_lists = delta_zone->delta_lists; u32 tail_guard_index = delta_zone->list_count + 1; spacing = (delta_zone->size - used_space) / delta_zone->list_count; delta_zone->new_offsets[0] = 0; for (i = 0; i <= delta_zone->list_count; i++) { delta_zone->new_offsets[i + 1] = (delta_zone->new_offsets[i] + get_delta_list_byte_size(&delta_lists[i]) + spacing); delta_zone->new_offsets[i] *= BITS_PER_BYTE; delta_zone->new_offsets[i] += delta_lists[i].start % BITS_PER_BYTE; if (i == 0) delta_zone->new_offsets[i + 1] -= spacing / 2; if (i + 1 == growing_index) delta_zone->new_offsets[i + 1] += growing_size; } delta_zone->new_offsets[tail_guard_index] = (delta_zone->size * BITS_PER_BYTE - delta_lists[tail_guard_index].size); } static void rebalance_lists(struct delta_zone *delta_zone) { struct delta_list *delta_lists; u32 i; size_t used_space = 0; /* Extend and balance memory to receive the delta lists */ delta_lists = delta_zone->delta_lists; for (i = 0; i <= delta_zone->list_count + 1; i++) used_space += get_delta_list_byte_size(&delta_lists[i]); compute_new_list_offsets(delta_zone, 0, 0, used_space); for (i = 1; i <= delta_zone->list_count + 1; i++) delta_lists[i].start = delta_zone->new_offsets[i]; } /* Start restoring a delta index from multiple input streams. */ int uds_start_restoring_delta_index(struct delta_index *delta_index, struct buffered_reader **buffered_readers, unsigned int reader_count) { int result; unsigned int zone_count = reader_count; u64 record_count = 0; u64 collision_count = 0; u32 first_list[MAX_ZONES]; u32 list_count[MAX_ZONES]; unsigned int z; u32 list_next = 0; const struct delta_zone *delta_zone; /* Read and validate each header. */ for (z = 0; z < zone_count; z++) { struct delta_index_header header; u8 buffer[sizeof(struct delta_index_header)]; size_t offset = 0; result = uds_read_from_buffered_reader(buffered_readers[z], buffer, sizeof(buffer)); if (result != UDS_SUCCESS) { return vdo_log_warning_strerror(result, "failed to read delta index header"); } memcpy(&header.magic, buffer, MAGIC_SIZE); offset += MAGIC_SIZE; decode_u32_le(buffer, &offset, &header.zone_number); decode_u32_le(buffer, &offset, &header.zone_count); decode_u32_le(buffer, &offset, &header.first_list); decode_u32_le(buffer, &offset, &header.list_count); decode_u64_le(buffer, &offset, &header.record_count); decode_u64_le(buffer, &offset, &header.collision_count); result = VDO_ASSERT(offset == sizeof(struct delta_index_header), "%zu bytes decoded of %zu expected", offset, sizeof(struct delta_index_header)); if (result != VDO_SUCCESS) { return vdo_log_warning_strerror(result, "failed to read delta index header"); } if (memcmp(header.magic, DELTA_INDEX_MAGIC, MAGIC_SIZE) != 0) { return vdo_log_warning_strerror(UDS_CORRUPT_DATA, "delta index file has bad magic number"); } if (zone_count != header.zone_count) { return vdo_log_warning_strerror(UDS_CORRUPT_DATA, "delta index files contain mismatched zone counts (%u,%u)", zone_count, header.zone_count); } if (header.zone_number != z) { return vdo_log_warning_strerror(UDS_CORRUPT_DATA, "delta index zone %u found in slot %u", header.zone_number, z); } first_list[z] = header.first_list; list_count[z] = header.list_count; record_count += header.record_count; collision_count += header.collision_count; if (first_list[z] != list_next) { return vdo_log_warning_strerror(UDS_CORRUPT_DATA, "delta index file for zone %u starts with list %u instead of list %u", z, first_list[z], list_next); } list_next += list_count[z]; } if (list_next != delta_index->list_count) { return vdo_log_warning_strerror(UDS_CORRUPT_DATA, "delta index files contain %u delta lists instead of %u delta lists", list_next, delta_index->list_count); } if (collision_count > record_count) { return vdo_log_warning_strerror(UDS_CORRUPT_DATA, "delta index files contain %llu collisions and %llu records", (unsigned long long) collision_count, (unsigned long long) record_count); } uds_reset_delta_index(delta_index); delta_index->delta_zones[0].record_count = record_count; delta_index->delta_zones[0].collision_count = collision_count; /* Read the delta lists and distribute them to the proper zones. */ for (z = 0; z < zone_count; z++) { u32 i; delta_index->load_lists[z] = 0; for (i = 0; i < list_count[z]; i++) { u16 delta_list_size; u32 list_number; unsigned int zone_number; u8 size_data[sizeof(u16)]; result = uds_read_from_buffered_reader(buffered_readers[z], size_data, sizeof(size_data)); if (result != UDS_SUCCESS) { return vdo_log_warning_strerror(result, "failed to read delta index size"); } delta_list_size = get_unaligned_le16(size_data); if (delta_list_size > 0) delta_index->load_lists[z] += 1; list_number = first_list[z] + i; zone_number = list_number / delta_index->lists_per_zone; delta_zone = &delta_index->delta_zones[zone_number]; list_number -= delta_zone->first_list; delta_zone->delta_lists[list_number + 1].size = delta_list_size; } } /* Prepare each zone to start receiving the delta list data. */ for (z = 0; z < delta_index->zone_count; z++) rebalance_lists(&delta_index->delta_zones[z]); return UDS_SUCCESS; } static int restore_delta_list_to_zone(struct delta_zone *delta_zone, const struct delta_list_save_info *save_info, const u8 *data) { struct delta_list *delta_list; u16 bit_count; u16 byte_count; u32 list_number = save_info->index - delta_zone->first_list; if (list_number >= delta_zone->list_count) { return vdo_log_warning_strerror(UDS_CORRUPT_DATA, "invalid delta list number %u not in range [%u,%u)", save_info->index, delta_zone->first_list, delta_zone->first_list + delta_zone->list_count); } delta_list = &delta_zone->delta_lists[list_number + 1]; if (delta_list->size == 0) { return vdo_log_warning_strerror(UDS_CORRUPT_DATA, "unexpected delta list number %u", save_info->index); } bit_count = delta_list->size + save_info->bit_offset; byte_count = BITS_TO_BYTES(bit_count); if (save_info->byte_count != byte_count) { return vdo_log_warning_strerror(UDS_CORRUPT_DATA, "unexpected delta list size %u != %u", save_info->byte_count, byte_count); } move_bits(data, save_info->bit_offset, delta_zone->memory, delta_list->start, delta_list->size); return UDS_SUCCESS; } static int restore_delta_list_data(struct delta_index *delta_index, unsigned int load_zone, struct buffered_reader *buffered_reader, u8 *data) { int result; struct delta_list_save_info save_info; u8 buffer[sizeof(struct delta_list_save_info)]; unsigned int new_zone; result = uds_read_from_buffered_reader(buffered_reader, buffer, sizeof(buffer)); if (result != UDS_SUCCESS) { return vdo_log_warning_strerror(result, "failed to read delta list data"); } save_info = (struct delta_list_save_info) { .tag = buffer[0], .bit_offset = buffer[1], .byte_count = get_unaligned_le16(&buffer[2]), .index = get_unaligned_le32(&buffer[4]), }; if ((save_info.bit_offset >= BITS_PER_BYTE) || (save_info.byte_count > DELTA_LIST_MAX_BYTE_COUNT)) { return vdo_log_warning_strerror(UDS_CORRUPT_DATA, "corrupt delta list data"); } /* Make sure the data is intended for this delta index. */ if (save_info.tag != delta_index->tag) return UDS_CORRUPT_DATA; if (save_info.index >= delta_index->list_count) { return vdo_log_warning_strerror(UDS_CORRUPT_DATA, "invalid delta list number %u of %u", save_info.index, delta_index->list_count); } result = uds_read_from_buffered_reader(buffered_reader, data, save_info.byte_count); if (result != UDS_SUCCESS) { return vdo_log_warning_strerror(result, "failed to read delta list data"); } delta_index->load_lists[load_zone] -= 1; new_zone = save_info.index / delta_index->lists_per_zone; return restore_delta_list_to_zone(&delta_index->delta_zones[new_zone], &save_info, data); } /* Restore delta lists from saved data. */ int uds_finish_restoring_delta_index(struct delta_index *delta_index, struct buffered_reader **buffered_readers, unsigned int reader_count) { int result; int saved_result = UDS_SUCCESS; unsigned int z; u8 *data; result = vdo_allocate(DELTA_LIST_MAX_BYTE_COUNT, u8, __func__, &data); if (result != VDO_SUCCESS) return result; for (z = 0; z < reader_count; z++) { while (delta_index->load_lists[z] > 0) { result = restore_delta_list_data(delta_index, z, buffered_readers[z], data); if (result != UDS_SUCCESS) { saved_result = result; break; } } } vdo_free(data); return saved_result; } int uds_check_guard_delta_lists(struct buffered_reader **buffered_readers, unsigned int reader_count) { int result; unsigned int z; u8 buffer[sizeof(struct delta_list_save_info)]; for (z = 0; z < reader_count; z++) { result = uds_read_from_buffered_reader(buffered_readers[z], buffer, sizeof(buffer)); if (result != UDS_SUCCESS) return result; if (buffer[0] != 'z') return UDS_CORRUPT_DATA; } return UDS_SUCCESS; } static int flush_delta_list(struct delta_zone *zone, u32 flush_index) { struct delta_list *delta_list; u8 buffer[sizeof(struct delta_list_save_info)]; int result; delta_list = &zone->delta_lists[flush_index + 1]; buffer[0] = zone->tag; buffer[1] = delta_list->start % BITS_PER_BYTE; put_unaligned_le16(get_delta_list_byte_size(delta_list), &buffer[2]); put_unaligned_le32(zone->first_list + flush_index, &buffer[4]); result = uds_write_to_buffered_writer(zone->buffered_writer, buffer, sizeof(buffer)); if (result != UDS_SUCCESS) { vdo_log_warning_strerror(result, "failed to write delta list memory"); return result; } result = uds_write_to_buffered_writer(zone->buffered_writer, zone->memory + get_delta_list_byte_start(delta_list), get_delta_list_byte_size(delta_list)); if (result != UDS_SUCCESS) vdo_log_warning_strerror(result, "failed to write delta list memory"); return result; } /* Start saving a delta index zone to a buffered output stream. */ int uds_start_saving_delta_index(const struct delta_index *delta_index, unsigned int zone_number, struct buffered_writer *buffered_writer) { int result; u32 i; struct delta_zone *delta_zone; u8 buffer[sizeof(struct delta_index_header)]; size_t offset = 0; delta_zone = &delta_index->delta_zones[zone_number]; memcpy(buffer, DELTA_INDEX_MAGIC, MAGIC_SIZE); offset += MAGIC_SIZE; encode_u32_le(buffer, &offset, zone_number); encode_u32_le(buffer, &offset, delta_index->zone_count); encode_u32_le(buffer, &offset, delta_zone->first_list); encode_u32_le(buffer, &offset, delta_zone->list_count); encode_u64_le(buffer, &offset, delta_zone->record_count); encode_u64_le(buffer, &offset, delta_zone->collision_count); result = VDO_ASSERT(offset == sizeof(struct delta_index_header), "%zu bytes encoded of %zu expected", offset, sizeof(struct delta_index_header)); if (result != VDO_SUCCESS) return result; result = uds_write_to_buffered_writer(buffered_writer, buffer, offset); if (result != UDS_SUCCESS) return vdo_log_warning_strerror(result, "failed to write delta index header"); for (i = 0; i < delta_zone->list_count; i++) { u8 data[sizeof(u16)]; struct delta_list *delta_list; delta_list = &delta_zone->delta_lists[i + 1]; put_unaligned_le16(delta_list->size, data); result = uds_write_to_buffered_writer(buffered_writer, data, sizeof(data)); if (result != UDS_SUCCESS) return vdo_log_warning_strerror(result, "failed to write delta list size"); } delta_zone->buffered_writer = buffered_writer; return UDS_SUCCESS; } int uds_finish_saving_delta_index(const struct delta_index *delta_index, unsigned int zone_number) { int result; int first_error = UDS_SUCCESS; u32 i; struct delta_zone *delta_zone; struct delta_list *delta_list; delta_zone = &delta_index->delta_zones[zone_number]; for (i = 0; i < delta_zone->list_count; i++) { delta_list = &delta_zone->delta_lists[i + 1]; if (delta_list->size > 0) { result = flush_delta_list(delta_zone, i); if ((result != UDS_SUCCESS) && (first_error == UDS_SUCCESS)) first_error = result; } } delta_zone->buffered_writer = NULL; return first_error; } int uds_write_guard_delta_list(struct buffered_writer *buffered_writer) { int result; u8 buffer[sizeof(struct delta_list_save_info)]; memset(buffer, 0, sizeof(struct delta_list_save_info)); buffer[0] = 'z'; result = uds_write_to_buffered_writer(buffered_writer, buffer, sizeof(buffer)); if (result != UDS_SUCCESS) vdo_log_warning_strerror(result, "failed to write guard delta list"); return UDS_SUCCESS; } size_t uds_compute_delta_index_save_bytes(u32 list_count, size_t memory_size) { /* One zone will use at least as much memory as other zone counts. */ return (sizeof(struct delta_index_header) + list_count * (sizeof(struct delta_list_save_info) + 1) + get_zone_memory_size(1, memory_size)); } static int assert_not_at_end(const struct delta_index_entry *delta_entry) { int result = VDO_ASSERT(!delta_entry->at_end, "operation is invalid because the list entry is at the end of the delta list"); if (result != VDO_SUCCESS) result = UDS_BAD_STATE; return result; } /* * Prepare to search for an entry in the specified delta list. * * This is always the first function to be called when dealing with delta index entries. It is * always followed by calls to uds_next_delta_index_entry() to iterate through a delta list. The * fields of the delta_index_entry argument will be set up for iteration, but will not contain an * entry from the list. */ int uds_start_delta_index_search(const struct delta_index *delta_index, u32 list_number, u32 key, struct delta_index_entry *delta_entry) { int result; unsigned int zone_number; struct delta_zone *delta_zone; struct delta_list *delta_list; result = VDO_ASSERT((list_number < delta_index->list_count), "Delta list number (%u) is out of range (%u)", list_number, delta_index->list_count); if (result != VDO_SUCCESS) return UDS_CORRUPT_DATA; zone_number = list_number / delta_index->lists_per_zone; delta_zone = &delta_index->delta_zones[zone_number]; list_number -= delta_zone->first_list; result = VDO_ASSERT((list_number < delta_zone->list_count), "Delta list number (%u) is out of range (%u) for zone (%u)", list_number, delta_zone->list_count, zone_number); if (result != VDO_SUCCESS) return UDS_CORRUPT_DATA; if (delta_index->mutable) { delta_list = &delta_zone->delta_lists[list_number + 1]; } else { u32 end_offset; /* * Translate the immutable delta list header into a temporary * full delta list header. */ delta_list = &delta_entry->temp_delta_list; delta_list->start = get_immutable_start(delta_zone->memory, list_number); end_offset = get_immutable_start(delta_zone->memory, list_number + 1); delta_list->size = end_offset - delta_list->start; delta_list->save_key = 0; delta_list->save_offset = 0; } if (key > delta_list->save_key) { delta_entry->key = delta_list->save_key; delta_entry->offset = delta_list->save_offset; } else { delta_entry->key = 0; delta_entry->offset = 0; if (key == 0) { /* * This usually means we're about to walk the entire delta list, so get all * of it into the CPU cache. */ uds_prefetch_range(&delta_zone->memory[delta_list->start / BITS_PER_BYTE], delta_list->size / BITS_PER_BYTE, false); } } delta_entry->at_end = false; delta_entry->delta_zone = delta_zone; delta_entry->delta_list = delta_list; delta_entry->entry_bits = 0; delta_entry->is_collision = false; delta_entry->list_number = list_number; delta_entry->list_overflow = false; delta_entry->value_bits = delta_zone->value_bits; return UDS_SUCCESS; } static inline u64 get_delta_entry_offset(const struct delta_index_entry *delta_entry) { return delta_entry->delta_list->start + delta_entry->offset; } /* * Decode a delta index entry delta value. The delta_index_entry basically describes the previous * list entry, and has had its offset field changed to point to the subsequent entry. We decode the * bit stream and update the delta_list_entry to describe the entry. */ static inline void decode_delta(struct delta_index_entry *delta_entry) { int key_bits; u32 delta; const struct delta_zone *delta_zone = delta_entry->delta_zone; const u8 *memory = delta_zone->memory; u64 delta_offset = get_delta_entry_offset(delta_entry) + delta_entry->value_bits; const u8 *addr = memory + delta_offset / BITS_PER_BYTE; int offset = delta_offset % BITS_PER_BYTE; u32 data = get_unaligned_le32(addr) >> offset; addr += sizeof(u32); key_bits = delta_zone->min_bits; delta = data & ((1 << key_bits) - 1); if (delta >= delta_zone->min_keys) { data >>= key_bits; if (data == 0) { key_bits = sizeof(u32) * BITS_PER_BYTE - offset; while ((data = get_unaligned_le32(addr)) == 0) { addr += sizeof(u32); key_bits += sizeof(u32) * BITS_PER_BYTE; } } key_bits += ffs(data); delta += ((key_bits - delta_zone->min_bits - 1) * delta_zone->incr_keys); } delta_entry->delta = delta; delta_entry->key += delta; /* Check for a collision, a delta of zero after the start. */ if (unlikely((delta == 0) && (delta_entry->offset > 0))) { delta_entry->is_collision = true; delta_entry->entry_bits = delta_entry->value_bits + key_bits + COLLISION_BITS; } else { delta_entry->is_collision = false; delta_entry->entry_bits = delta_entry->value_bits + key_bits; } } noinline int uds_next_delta_index_entry(struct delta_index_entry *delta_entry) { int result; const struct delta_list *delta_list; u32 next_offset; u16 size; result = assert_not_at_end(delta_entry); if (result != UDS_SUCCESS) return result; delta_list = delta_entry->delta_list; delta_entry->offset += delta_entry->entry_bits; size = delta_list->size; if (unlikely(delta_entry->offset >= size)) { delta_entry->at_end = true; delta_entry->delta = 0; delta_entry->is_collision = false; result = VDO_ASSERT((delta_entry->offset == size), "next offset past end of delta list"); if (result != VDO_SUCCESS) result = UDS_CORRUPT_DATA; return result; } decode_delta(delta_entry); next_offset = delta_entry->offset + delta_entry->entry_bits; if (next_offset > size) { /* * This is not an assertion because uds_validate_chapter_index_page() wants to * handle this error. */ vdo_log_warning("Decoded past the end of the delta list"); return UDS_CORRUPT_DATA; } return UDS_SUCCESS; } int uds_remember_delta_index_offset(const struct delta_index_entry *delta_entry) { int result; struct delta_list *delta_list = delta_entry->delta_list; result = VDO_ASSERT(!delta_entry->is_collision, "entry is not a collision"); if (result != VDO_SUCCESS) return result; delta_list->save_key = delta_entry->key - delta_entry->delta; delta_list->save_offset = delta_entry->offset; return UDS_SUCCESS; } static void set_delta(struct delta_index_entry *delta_entry, u32 delta) { const struct delta_zone *delta_zone = delta_entry->delta_zone; u32 key_bits = (delta_zone->min_bits + ((delta_zone->incr_keys - delta_zone->min_keys + delta) / delta_zone->incr_keys)); delta_entry->delta = delta; delta_entry->entry_bits = delta_entry->value_bits + key_bits; } static void get_collision_name(const struct delta_index_entry *entry, u8 *name) { u64 offset = get_delta_entry_offset(entry) + entry->entry_bits - COLLISION_BITS; const u8 *addr = entry->delta_zone->memory + offset / BITS_PER_BYTE; int size = COLLISION_BYTES; int shift = offset % BITS_PER_BYTE; while (--size >= 0) *name++ = get_unaligned_le16(addr++) >> shift; } static void set_collision_name(const struct delta_index_entry *entry, const u8 *name) { u64 offset = get_delta_entry_offset(entry) + entry->entry_bits - COLLISION_BITS; u8 *addr = entry->delta_zone->memory + offset / BITS_PER_BYTE; int size = COLLISION_BYTES; int shift = offset % BITS_PER_BYTE; u16 mask = ~((u16) 0xFF << shift); u16 data; while (--size >= 0) { data = (get_unaligned_le16(addr) & mask) | (*name++ << shift); put_unaligned_le16(data, addr++); } } int uds_get_delta_index_entry(const struct delta_index *delta_index, u32 list_number, u32 key, const u8 *name, struct delta_index_entry *delta_entry) { int result; result = uds_start_delta_index_search(delta_index, list_number, key, delta_entry); if (result != UDS_SUCCESS) return result; do { result = uds_next_delta_index_entry(delta_entry); if (result != UDS_SUCCESS) return result; } while (!delta_entry->at_end && (key > delta_entry->key)); result = uds_remember_delta_index_offset(delta_entry); if (result != UDS_SUCCESS) return result; if (!delta_entry->at_end && (key == delta_entry->key)) { struct delta_index_entry collision_entry = *delta_entry; for (;;) { u8 full_name[COLLISION_BYTES]; result = uds_next_delta_index_entry(&collision_entry); if (result != UDS_SUCCESS) return result; if (collision_entry.at_end || !collision_entry.is_collision) break; get_collision_name(&collision_entry, full_name); if (memcmp(full_name, name, COLLISION_BYTES) == 0) { *delta_entry = collision_entry; break; } } } return UDS_SUCCESS; } int uds_get_delta_entry_collision(const struct delta_index_entry *delta_entry, u8 *name) { int result; result = assert_not_at_end(delta_entry); if (result != UDS_SUCCESS) return result; result = VDO_ASSERT(delta_entry->is_collision, "Cannot get full block name from a non-collision delta index entry"); if (result != VDO_SUCCESS) return UDS_BAD_STATE; get_collision_name(delta_entry, name); return UDS_SUCCESS; } u32 uds_get_delta_entry_value(const struct delta_index_entry *delta_entry) { return get_field(delta_entry->delta_zone->memory, get_delta_entry_offset(delta_entry), delta_entry->value_bits); } static int assert_mutable_entry(const struct delta_index_entry *delta_entry) { int result = VDO_ASSERT((delta_entry->delta_list != &delta_entry->temp_delta_list), "delta index is mutable"); if (result != VDO_SUCCESS) result = UDS_BAD_STATE; return result; } int uds_set_delta_entry_value(const struct delta_index_entry *delta_entry, u32 value) { int result; u32 value_mask = (1 << delta_entry->value_bits) - 1; result = assert_mutable_entry(delta_entry); if (result != UDS_SUCCESS) return result; result = assert_not_at_end(delta_entry); if (result != UDS_SUCCESS) return result; result = VDO_ASSERT((value & value_mask) == value, "Value (%u) being set in a delta index is too large (must fit in %u bits)", value, delta_entry->value_bits); if (result != VDO_SUCCESS) return UDS_INVALID_ARGUMENT; set_field(value, delta_entry->delta_zone->memory, get_delta_entry_offset(delta_entry), delta_entry->value_bits); return UDS_SUCCESS; } /* * Extend the memory used by the delta lists by adding growing_size bytes before the list indicated * by growing_index, then rebalancing the lists in the new chunk. */ static int extend_delta_zone(struct delta_zone *delta_zone, u32 growing_index, size_t growing_size) { ktime_t start_time; ktime_t end_time; struct delta_list *delta_lists; u32 i; size_t used_space; /* Calculate the amount of space that is or will be in use. */ start_time = current_time_ns(CLOCK_MONOTONIC); delta_lists = delta_zone->delta_lists; used_space = growing_size; for (i = 0; i <= delta_zone->list_count + 1; i++) used_space += get_delta_list_byte_size(&delta_lists[i]); if (delta_zone->size < used_space) return UDS_OVERFLOW; /* Compute the new offsets of the delta lists. */ compute_new_list_offsets(delta_zone, growing_index, growing_size, used_space); /* * When we rebalance the delta list, we will include the end guard list in the rebalancing. * It contains the end guard data, which must be copied. */ rebalance_delta_zone(delta_zone, 1, delta_zone->list_count + 1); end_time = current_time_ns(CLOCK_MONOTONIC); delta_zone->rebalance_count++; delta_zone->rebalance_time += ktime_sub(end_time, start_time); return UDS_SUCCESS; } static int insert_bits(struct delta_index_entry *delta_entry, u16 size) { u64 free_before; u64 free_after; u64 source; u64 destination; u32 count; bool before_flag; u8 *memory; struct delta_zone *delta_zone = delta_entry->delta_zone; struct delta_list *delta_list = delta_entry->delta_list; /* Compute bits in use before and after the inserted bits. */ u32 total_size = delta_list->size; u32 before_size = delta_entry->offset; u32 after_size = total_size - delta_entry->offset; if (total_size + size > U16_MAX) { delta_entry->list_overflow = true; delta_zone->overflow_count++; return UDS_OVERFLOW; } /* Compute bits available before and after the delta list. */ free_before = (delta_list[0].start - (delta_list[-1].start + delta_list[-1].size)); free_after = (delta_list[1].start - (delta_list[0].start + delta_list[0].size)); if ((size <= free_before) && (size <= free_after)) { /* * We have enough space to use either before or after the list. Select the smaller * amount of data. If it is exactly the same, try to take from the larger amount of * free space. */ if (before_size < after_size) before_flag = true; else if (after_size < before_size) before_flag = false; else before_flag = free_before > free_after; } else if (size <= free_before) { /* There is space before but not after. */ before_flag = true; } else if (size <= free_after) { /* There is space after but not before. */ before_flag = false; } else { /* * Neither of the surrounding spaces is large enough for this request. Extend * and/or rebalance the delta list memory choosing to move the least amount of * data. */ int result; u32 growing_index = delta_entry->list_number + 1; before_flag = before_size < after_size; if (!before_flag) growing_index++; result = extend_delta_zone(delta_zone, growing_index, BITS_TO_BYTES(size)); if (result != UDS_SUCCESS) return result; } delta_list->size += size; if (before_flag) { source = delta_list->start; destination = source - size; delta_list->start -= size; count = before_size; } else { source = delta_list->start + delta_entry->offset; destination = source + size; count = after_size; } memory = delta_zone->memory; move_bits(memory, source, memory, destination, count); return UDS_SUCCESS; } static void encode_delta(const struct delta_index_entry *delta_entry) { u32 temp; u32 t1; u32 t2; u64 offset; const struct delta_zone *delta_zone = delta_entry->delta_zone; u8 *memory = delta_zone->memory; offset = get_delta_entry_offset(delta_entry) + delta_entry->value_bits; if (delta_entry->delta < delta_zone->min_keys) { set_field(delta_entry->delta, memory, offset, delta_zone->min_bits); return; } temp = delta_entry->delta - delta_zone->min_keys; t1 = (temp % delta_zone->incr_keys) + delta_zone->min_keys; t2 = temp / delta_zone->incr_keys; set_field(t1, memory, offset, delta_zone->min_bits); set_zero(memory, offset + delta_zone->min_bits, t2); set_field(1, memory, offset + delta_zone->min_bits + t2, 1); } static void encode_entry(const struct delta_index_entry *delta_entry, u32 value, const u8 *name) { u8 *memory = delta_entry->delta_zone->memory; u64 offset = get_delta_entry_offset(delta_entry); set_field(value, memory, offset, delta_entry->value_bits); encode_delta(delta_entry); if (name != NULL) set_collision_name(delta_entry, name); } /* * Create a new entry in the delta index. If the entry is a collision, the full 256 bit name must * be provided. */ int uds_put_delta_index_entry(struct delta_index_entry *delta_entry, u32 key, u32 value, const u8 *name) { int result; struct delta_zone *delta_zone; result = assert_mutable_entry(delta_entry); if (result != UDS_SUCCESS) return result; if (delta_entry->is_collision) { /* * The caller wants us to insert a collision entry onto a collision entry. This * happens when we find a collision and attempt to add the name again to the index. * This is normally a fatal error unless we are replaying a closed chapter while we * are rebuilding a volume index. */ return UDS_DUPLICATE_NAME; } if (delta_entry->offset < delta_entry->delta_list->save_offset) { /* * The saved entry offset is after the new entry and will no longer be valid, so * replace it with the insertion point. */ result = uds_remember_delta_index_offset(delta_entry); if (result != UDS_SUCCESS) return result; } if (name != NULL) { /* Insert a collision entry which is placed after this entry. */ result = assert_not_at_end(delta_entry); if (result != UDS_SUCCESS) return result; result = VDO_ASSERT((key == delta_entry->key), "incorrect key for collision entry"); if (result != VDO_SUCCESS) return result; delta_entry->offset += delta_entry->entry_bits; set_delta(delta_entry, 0); delta_entry->is_collision = true; delta_entry->entry_bits += COLLISION_BITS; result = insert_bits(delta_entry, delta_entry->entry_bits); } else if (delta_entry->at_end) { /* Insert a new entry at the end of the delta list. */ result = VDO_ASSERT((key >= delta_entry->key), "key past end of list"); if (result != VDO_SUCCESS) return result; set_delta(delta_entry, key - delta_entry->key); delta_entry->key = key; delta_entry->at_end = false; result = insert_bits(delta_entry, delta_entry->entry_bits); } else { u16 old_entry_size; u16 additional_size; struct delta_index_entry next_entry; u32 next_value; /* * Insert a new entry which requires the delta in the following entry to be * updated. */ result = VDO_ASSERT((key < delta_entry->key), "key precedes following entry"); if (result != VDO_SUCCESS) return result; result = VDO_ASSERT((key >= delta_entry->key - delta_entry->delta), "key effects following entry's delta"); if (result != VDO_SUCCESS) return result; old_entry_size = delta_entry->entry_bits; next_entry = *delta_entry; next_value = uds_get_delta_entry_value(&next_entry); set_delta(delta_entry, key - (delta_entry->key - delta_entry->delta)); delta_entry->key = key; set_delta(&next_entry, next_entry.key - key); next_entry.offset += delta_entry->entry_bits; /* The two new entries are always bigger than the single entry being replaced. */ additional_size = (delta_entry->entry_bits + next_entry.entry_bits - old_entry_size); result = insert_bits(delta_entry, additional_size); if (result != UDS_SUCCESS) return result; encode_entry(&next_entry, next_value, NULL); } if (result != UDS_SUCCESS) return result; encode_entry(delta_entry, value, name); delta_zone = delta_entry->delta_zone; delta_zone->record_count++; delta_zone->collision_count += delta_entry->is_collision ? 1 : 0; return UDS_SUCCESS; } static void delete_bits(const struct delta_index_entry *delta_entry, int size) { u64 source; u64 destination; u32 count; bool before_flag; struct delta_list *delta_list = delta_entry->delta_list; u8 *memory = delta_entry->delta_zone->memory; /* Compute bits retained before and after the deleted bits. */ u32 total_size = delta_list->size; u32 before_size = delta_entry->offset; u32 after_size = total_size - delta_entry->offset - size; /* * Determine whether to add to the available space either before or after the delta list. * We prefer to move the least amount of data. If it is exactly the same, try to add to the * smaller amount of free space. */ if (before_size < after_size) { before_flag = true; } else if (after_size < before_size) { before_flag = false; } else { u64 free_before = (delta_list[0].start - (delta_list[-1].start + delta_list[-1].size)); u64 free_after = (delta_list[1].start - (delta_list[0].start + delta_list[0].size)); before_flag = (free_before < free_after); } delta_list->size -= size; if (before_flag) { source = delta_list->start; destination = source + size; delta_list->start += size; count = before_size; } else { destination = delta_list->start + delta_entry->offset; source = destination + size; count = after_size; } move_bits(memory, source, memory, destination, count); } int uds_remove_delta_index_entry(struct delta_index_entry *delta_entry) { int result; struct delta_index_entry next_entry; struct delta_zone *delta_zone; struct delta_list *delta_list; result = assert_mutable_entry(delta_entry); if (result != UDS_SUCCESS) return result; next_entry = *delta_entry; result = uds_next_delta_index_entry(&next_entry); if (result != UDS_SUCCESS) return result; delta_zone = delta_entry->delta_zone; if (delta_entry->is_collision) { /* This is a collision entry, so just remove it. */ delete_bits(delta_entry, delta_entry->entry_bits); next_entry.offset = delta_entry->offset; delta_zone->collision_count -= 1; } else if (next_entry.at_end) { /* This entry is at the end of the list, so just remove it. */ delete_bits(delta_entry, delta_entry->entry_bits); next_entry.key -= delta_entry->delta; next_entry.offset = delta_entry->offset; } else { /* The delta in the next entry needs to be updated. */ u32 next_value = uds_get_delta_entry_value(&next_entry); u16 old_size = delta_entry->entry_bits + next_entry.entry_bits; if (next_entry.is_collision) { next_entry.is_collision = false; delta_zone->collision_count -= 1; } set_delta(&next_entry, delta_entry->delta + next_entry.delta); next_entry.offset = delta_entry->offset; /* The one new entry is always smaller than the two entries being replaced. */ delete_bits(delta_entry, old_size - next_entry.entry_bits); encode_entry(&next_entry, next_value, NULL); } delta_zone->record_count--; delta_zone->discard_count++; *delta_entry = next_entry; delta_list = delta_entry->delta_list; if (delta_entry->offset < delta_list->save_offset) { /* The saved entry offset is no longer valid. */ delta_list->save_key = 0; delta_list->save_offset = 0; } return UDS_SUCCESS; } void uds_get_delta_index_stats(const struct delta_index *delta_index, struct delta_index_stats *stats) { unsigned int z; const struct delta_zone *delta_zone; memset(stats, 0, sizeof(struct delta_index_stats)); for (z = 0; z < delta_index->zone_count; z++) { delta_zone = &delta_index->delta_zones[z]; stats->rebalance_time += delta_zone->rebalance_time; stats->rebalance_count += delta_zone->rebalance_count; stats->record_count += delta_zone->record_count; stats->collision_count += delta_zone->collision_count; stats->discard_count += delta_zone->discard_count; stats->overflow_count += delta_zone->overflow_count; stats->list_count += delta_zone->list_count; } } size_t uds_compute_delta_index_size(u32 entry_count, u32 mean_delta, u32 payload_bits) { u16 min_bits; u32 incr_keys; u32 min_keys; compute_coding_constants(mean_delta, &min_bits, &min_keys, &incr_keys); /* On average, each delta is encoded into about min_bits + 1.5 bits. */ return entry_count * (payload_bits + min_bits + 1) + entry_count / 2; } u32 uds_get_delta_index_page_count(u32 entry_count, u32 list_count, u32 mean_delta, u32 payload_bits, size_t bytes_per_page) { unsigned int bits_per_delta_list; unsigned int bits_per_page; size_t bits_per_index; /* Compute the expected number of bits needed for all the entries. */ bits_per_index = uds_compute_delta_index_size(entry_count, mean_delta, payload_bits); bits_per_delta_list = bits_per_index / list_count; /* Add in the immutable delta list headers. */ bits_per_index += list_count * IMMUTABLE_HEADER_SIZE; /* Compute the number of usable bits on an immutable index page. */ bits_per_page = ((bytes_per_page - sizeof(struct delta_page_header)) * BITS_PER_BYTE); /* * Reduce the bits per page by one immutable delta list header and one delta list to * account for internal fragmentation. */ bits_per_page -= IMMUTABLE_HEADER_SIZE + bits_per_delta_list; /* Now compute the number of pages needed. */ return DIV_ROUND_UP(bits_per_index, bits_per_page); } void uds_log_delta_index_entry(struct delta_index_entry *delta_entry) { vdo_log_ratelimit(vdo_log_info, "List 0x%X Key 0x%X Offset 0x%X%s%s List_size 0x%X%s", delta_entry->list_number, delta_entry->key, delta_entry->offset, delta_entry->at_end ? " end" : "", delta_entry->is_collision ? " collision" : "", delta_entry->delta_list->size, delta_entry->list_overflow ? " overflow" : ""); delta_entry->list_overflow = false; }
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