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* Author: Kent Overstreet <kmo@daterainc.com>
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#define BITMASK(name, type, field, offset, size) \
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static inline uint64_t name(const type *k) \
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{ return (k->field >> offset) & ~(((uint64_t) ~0) << size); } \
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static inline void SET_##name(type *k, uint64_t v) \
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k->field &= ~(~((uint64_t) ~0 << size) << offset); \
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k->field |= v << offset; \
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static const char bcache_magic[] = {
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0xc6, 0x85, 0x73, 0xf6, 0x4e, 0x1a, 0x45, 0xca,
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0x82, 0x65, 0xf5, 0x7f, 0x48, 0xba, 0x6d, 0x81 };
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* Version 0: Cache device
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* Version 1: Backing device
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* Version 2: Seed pointer into btree node checksum
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* Version 3: Cache device with new UUID format
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* Version 4: Backing device with data offset
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#define BCACHE_SB_VERSION_CDEV 0
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#define BCACHE_SB_VERSION_BDEV 1
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#define BCACHE_SB_VERSION_CDEV_WITH_UUID 3
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#define BCACHE_SB_VERSION_BDEV_WITH_OFFSET 4
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#define BCACHE_SB_MAX_VERSION 4
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#define SB_LABEL_SIZE 32
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#define SB_JOURNAL_BUCKETS 256U
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#define BDEV_DATA_START_DEFAULT 16 /* sectors */
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#define SB_START (SB_SECTOR * 512)
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uint64_t offset; /* sector where this sb was written */
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uint8_t label[SB_LABEL_SIZE];
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uint64_t nbuckets; /* device size */
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uint16_t block_size; /* sectors */
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uint16_t bucket_size; /* sectors */
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* block_size from the cache device section is still used by
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* backing devices, so don't add anything here until we fix
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* things to not need it for backing devices anymore
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uint32_t last_mount; /* time_t */
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uint16_t first_bucket;
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uint16_t njournal_buckets;
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uint64_t d[SB_JOURNAL_BUCKETS]; /* journal buckets */
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static inline bool SB_IS_BDEV(const struct cache_sb *sb)
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return sb->version == BCACHE_SB_VERSION_BDEV
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|| sb->version == BCACHE_SB_VERSION_BDEV_WITH_OFFSET;
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BITMASK(CACHE_SYNC, struct cache_sb, flags, 0, 1);
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BITMASK(CACHE_DISCARD, struct cache_sb, flags, 1, 1);
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BITMASK(CACHE_REPLACEMENT, struct cache_sb, flags, 2, 3);
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#define CACHE_REPLACEMENT_LRU 0U
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#define CACHE_REPLACEMENT_FIFO 1U
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#define CACHE_REPLACEMENT_RANDOM 2U
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BITMASK(BDEV_CACHE_MODE, struct cache_sb, flags, 0, 4);
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#define CACHE_MODE_WRITETHROUGH 0U
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#define CACHE_MODE_WRITEBACK 1U
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#define CACHE_MODE_WRITEAROUND 2U
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#define CACHE_MODE_NONE 3U
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BITMASK(BDEV_STATE, struct cache_sb, flags, 61, 2);
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#define BDEV_STATE_NONE 0U
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#define BDEV_STATE_CLEAN 1U
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#define BDEV_STATE_DIRTY 2U
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#define BDEV_STATE_STALE 3U
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uint64_t crc64(const void *_data, size_t len);
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#define node(i, j) ((void *) ((i)->d + (j)))
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#define end(i) node(i, (i)->keys)
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#define csum_set(i) \
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crc64(((void *) (i)) + 8, ((void *) end(i)) - (((void *) (i)) + 8))