125 lines
2.7 KiB
C
125 lines
2.7 KiB
C
#pragma once
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#include "crc32c.h"
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#define MIN_JOURNAL_SIZE 4*1024*1024
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#define JOURNAL_MAGIC 0x4A33
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#define JOURNAL_BUFFER_SIZE 4*1024*1024
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// Journal entries
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// Journal entries are linked to each other by their crc32 value
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// The journal is almost a blockchain, because object versions constantly increase
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#define JE_START 0x01
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#define JE_SMALL_WRITE 0x02
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#define JE_BIG_WRITE 0x03
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#define JE_STABLE 0x04
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#define JE_DELETE 0x05
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// crc32c comes first to ease calculation and is equal to crc32()
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struct __attribute__((__packed__)) journal_entry_start
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{
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uint32_t crc32;
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uint16_t magic;
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uint16_t type;
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uint32_t size;
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uint32_t crc32_replaced;
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uint64_t journal_start;
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};
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struct __attribute__((__packed__)) journal_entry_small_write
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{
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uint32_t crc32;
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uint16_t magic;
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uint16_t type;
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uint32_t size;
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uint32_t crc32_prev;
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object_id oid;
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uint64_t version;
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uint32_t offset;
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uint32_t len;
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// small_write entries contain <len> bytes of data, but data is stored in the next journal sector
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};
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struct __attribute__((__packed__)) journal_entry_big_write
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{
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uint32_t crc32;
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uint16_t magic;
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uint16_t type;
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uint32_t size;
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uint32_t crc32_prev;
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object_id oid;
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uint64_t version;
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uint64_t block;
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};
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struct __attribute__((__packed__)) journal_entry_stable
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{
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uint32_t crc32;
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uint16_t magic;
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uint16_t type;
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uint32_t size;
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uint32_t crc32_prev;
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object_id oid;
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uint64_t version;
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};
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struct __attribute__((__packed__)) journal_entry_del
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{
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uint32_t crc32;
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uint16_t magic;
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uint16_t type;
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uint32_t size;
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uint32_t crc32_prev;
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object_id oid;
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uint64_t version;
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};
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struct __attribute__((__packed__)) journal_entry
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{
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union
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{
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struct __attribute__((__packed__))
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{
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uint32_t crc32;
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uint16_t magic;
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uint16_t type;
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uint32_t size;
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uint32_t crc32_prev;
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};
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journal_entry_start start;
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journal_entry_small_write small_write;
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journal_entry_big_write big_write;
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journal_entry_stable stable;
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journal_entry_del del;
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};
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};
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inline uint32_t je_crc32(journal_entry *je)
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{
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return crc32c_zero4(((uint8_t*)je)+4, je->size-4);
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}
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struct journal_sector_info_t
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{
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uint64_t offset;
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uint64_t usage_count;
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};
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struct journal_t
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{
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int fd;
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uint64_t device_size;
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uint64_t offset, len;
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uint64_t next_free = 512;
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uint64_t used_start = 512;
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uint32_t crc32_last = 0;
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// Current sector(s) used for writing
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uint8_t *sector_buf;
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journal_sector_info_t *sector_info;
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uint64_t sector_count;
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uint64_t cur_sector = 0;
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uint64_t in_sector_pos = 0;
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};
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