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tromcho.net/src/blockstore/blockstore_disk.h
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// Copyright (c) Vitaliy Filippov, 2019+
// License: VNPL-1.1 (see README.md for details)
#pragma once
#include <stdint.h>
#include <string>
#include <map>
// Memory alignment for direct I/O (usually 512 bytes)
#ifndef DIRECT_IO_ALIGNMENT
#define DIRECT_IO_ALIGNMENT 512
#endif
#define BLOCKSTORE_CSUM_NONE 0
// Lower byte of checksum type is its length
#define BLOCKSTORE_CSUM_CRC32C 0x104
#define MOCK_DATA_FD 1000
#define MOCK_META_FD 1001
#define MOCK_JOURNAL_FD 1002
class allocator_t;
struct blockstore_disk_t
{
std::string data_device, meta_device, journal_device;
uint32_t data_block_size;
uint64_t cfg_journal_size, cfg_data_size;
// Required write alignment and journal/metadata/data areas' location alignment
uint32_t disk_alignment = 4096;
// Journal block size - minimum_io_size of the journal device is the best choice
uint32_t journal_block_size = 4096;
// Metadata block size - minimum_io_size of the metadata device is the best choice
uint32_t meta_block_size = 4096;
// Atomic write size of the data block device
uint32_t atomic_write_size = 4096;
// Target free space in metadata blocks
uint32_t meta_block_target_free_space = 800;
// Sparse write tracking granularity. 4 KB is a good choice. Must be a multiple of disk_alignment
uint32_t bitmap_granularity = 4096;
// Data checksum type, BLOCKSTORE_CSUM_NONE or BLOCKSTORE_CSUM_CRC32C
uint32_t data_csum_type = BLOCKSTORE_CSUM_NONE;
// Checksum block size, must be a multiple of bitmap_granularity
uint32_t csum_block_size = 4096;
// By default, Blockstore locks all opened devices exclusively. This option can be used to disable locking
bool disable_flock = false;
// I/O modes for data, metadata and journal: direct or "" = O_DIRECT, cached = O_SYNC, directsync = O_DIRECT|O_SYNC
// O_SYNC without O_DIRECT = use Linux page cache for reads and writes
std::string data_io, meta_io, journal_io;
// It is safe to disable fsync() if drive write cache is writethrough
bool disable_data_fsync = false, disable_meta_fsync = false, disable_journal_fsync = false;
// Keep journal (buffered data) in memory?
bool inmemory_meta = true;
// Keep metadata in memory?
bool inmemory_journal = true;
// Data discard granularity and minimum size (for the sake of performance)
bool discard_on_start = false;
uint64_t min_discard_size = 1024*1024;
uint64_t discard_granularity = 0;
int meta_fd = -1, data_fd = -1, journal_fd = -1;
uint64_t meta_offset, meta_device_sect, meta_device_size, meta_area_size, min_meta_len, meta_format = 0;
uint64_t data_offset, data_device_sect, data_device_size, data_len;
uint64_t journal_offset, journal_device_sect, journal_device_size, journal_len;
uint64_t block_count = 0;
uint32_t clean_entry_bitmap_size = 0;
uint32_t clean_entry_size = 0, clean_dyn_size = 0; // for meta_v1/2
bool mock_mode = false;
void parse_config(std::map<std::string, std::string> & config);
void open_data();
void open_meta();
void open_journal();
void calc_lengths();
void check_lengths();
void close_all();
int trim_data(std::function<bool(uint64_t)> is_free);
inline uint64_t dirty_dyn_size(uint64_t offset, uint64_t len)
{
// Checksums may be partial if write is not aligned with csum_block_size
return clean_entry_bitmap_size + (csum_block_size && len > 0
? ((offset+len+csum_block_size-1)/csum_block_size - offset/csum_block_size)
* (data_csum_type & 0xFF)
: 0);
}
};