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@@ -0,0 +1,373 @@
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+#ifndef _LINUX_BCACHE_H
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+#define _LINUX_BCACHE_H
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+
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+/*
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+ * Bcache on disk data structures
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+ */
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+
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+#include <asm/types.h>
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+
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+#define BITMASK(name, type, field, offset, size) \
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+static inline __u64 name(const type *k) \
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+{ return (k->field >> offset) & ~(~0ULL << size); } \
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+ \
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+static inline void SET_##name(type *k, __u64 v) \
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+{ \
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+ k->field &= ~(~(~0ULL << size) << offset); \
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+ k->field |= (v & ~(~0ULL << size)) << offset; \
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+}
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+
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+/* Btree keys - all units are in sectors */
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+
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+struct bkey {
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+ __u64 high;
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+ __u64 low;
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+ __u64 ptr[];
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+};
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+
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+#define KEY_FIELD(name, field, offset, size) \
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+ BITMASK(name, struct bkey, field, offset, size)
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+
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+#define PTR_FIELD(name, offset, size) \
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+static inline __u64 name(const struct bkey *k, unsigned i) \
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+{ return (k->ptr[i] >> offset) & ~(~0ULL << size); } \
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+ \
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+static inline void SET_##name(struct bkey *k, unsigned i, __u64 v) \
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+{ \
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+ k->ptr[i] &= ~(~(~0ULL << size) << offset); \
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+ k->ptr[i] |= (v & ~(~0ULL << size)) << offset; \
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+}
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+
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+#define KEY_SIZE_BITS 16
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+
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+KEY_FIELD(KEY_PTRS, high, 60, 3)
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+KEY_FIELD(HEADER_SIZE, high, 58, 2)
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+KEY_FIELD(KEY_CSUM, high, 56, 2)
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+KEY_FIELD(KEY_PINNED, high, 55, 1)
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+KEY_FIELD(KEY_DIRTY, high, 36, 1)
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+
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+KEY_FIELD(KEY_SIZE, high, 20, KEY_SIZE_BITS)
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+KEY_FIELD(KEY_INODE, high, 0, 20)
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+
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+/* Next time I change the on disk format, KEY_OFFSET() won't be 64 bits */
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+
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+static inline __u64 KEY_OFFSET(const struct bkey *k)
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+{
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+ return k->low;
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+}
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+
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+static inline void SET_KEY_OFFSET(struct bkey *k, __u64 v)
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+{
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+ k->low = v;
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+}
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+
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+/*
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+ * The high bit being set is a relic from when we used it to do binary
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+ * searches - it told you where a key started. It's not used anymore,
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+ * and can probably be safely dropped.
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+ */
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+#define KEY(inode, offset, size) \
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+((struct bkey) { \
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+ .high = (1ULL << 63) | ((__u64) (size) << 20) | (inode), \
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+ .low = (offset) \
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+})
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+
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+#define ZERO_KEY KEY(0, 0, 0)
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+
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+#define MAX_KEY_INODE (~(~0 << 20))
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+#define MAX_KEY_OFFSET (~0ULL >> 1)
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+#define MAX_KEY KEY(MAX_KEY_INODE, MAX_KEY_OFFSET, 0)
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+
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+#define KEY_START(k) (KEY_OFFSET(k) - KEY_SIZE(k))
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+#define START_KEY(k) KEY(KEY_INODE(k), KEY_START(k), 0)
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+
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+#define PTR_DEV_BITS 12
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+
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+PTR_FIELD(PTR_DEV, 51, PTR_DEV_BITS)
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+PTR_FIELD(PTR_OFFSET, 8, 43)
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+PTR_FIELD(PTR_GEN, 0, 8)
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+
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+#define PTR_CHECK_DEV ((1 << PTR_DEV_BITS) - 1)
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+
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+#define PTR(gen, offset, dev) \
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+ ((((__u64) dev) << 51) | ((__u64) offset) << 8 | gen)
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+
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+/* Bkey utility code */
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+
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+static inline unsigned long bkey_u64s(const struct bkey *k)
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+{
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+ return (sizeof(struct bkey) / sizeof(__u64)) + KEY_PTRS(k);
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+}
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+
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+static inline unsigned long bkey_bytes(const struct bkey *k)
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+{
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+ return bkey_u64s(k) * sizeof(__u64);
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+}
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+
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+#define bkey_copy(_dest, _src) memcpy(_dest, _src, bkey_bytes(_src))
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+
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+static inline void bkey_copy_key(struct bkey *dest, const struct bkey *src)
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+{
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+ SET_KEY_INODE(dest, KEY_INODE(src));
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+ SET_KEY_OFFSET(dest, KEY_OFFSET(src));
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+}
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+
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+static inline struct bkey *bkey_next(const struct bkey *k)
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+{
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+ __u64 *d = (void *) k;
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+ return (struct bkey *) (d + bkey_u64s(k));
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+}
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+
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+static inline struct bkey *bkey_last(const struct bkey *k, unsigned nr_keys)
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+{
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+ __u64 *d = (void *) k;
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+ return (struct bkey *) (d + nr_keys);
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+}
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+/* Enough for a key with 6 pointers */
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+#define BKEY_PAD 8
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+
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+#define BKEY_PADDED(key) \
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+ union { struct bkey key; __u64 key ## _pad[BKEY_PAD]; }
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+
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+/* Superblock */
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+
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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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+ */
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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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+
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+#define SB_SECTOR 8
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+#define SB_SIZE 4096
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+#define SB_LABEL_SIZE 32
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+#define SB_JOURNAL_BUCKETS 256U
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+/* SB_JOURNAL_BUCKETS must be divisible by BITS_PER_LONG */
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+#define MAX_CACHES_PER_SET 8
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+
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+#define BDEV_DATA_START_DEFAULT 16 /* sectors */
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+
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+struct cache_sb {
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+ __u64 csum;
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+ __u64 offset; /* sector where this sb was written */
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+ __u64 version;
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+
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+ __u8 magic[16];
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+
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+ __u8 uuid[16];
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+ union {
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+ __u8 set_uuid[16];
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+ __u64 set_magic;
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+ };
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+ __u8 label[SB_LABEL_SIZE];
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+
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+ __u64 flags;
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+ __u64 seq;
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+ __u64 pad[8];
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+
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+ union {
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+ struct {
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+ /* Cache devices */
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+ __u64 nbuckets; /* device size */
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+
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+ __u16 block_size; /* sectors */
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+ __u16 bucket_size; /* sectors */
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+
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+ __u16 nr_in_set;
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+ __u16 nr_this_dev;
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+ };
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+ struct {
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+ /* Backing devices */
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+ __u64 data_offset;
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+
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+ /*
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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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+ */
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+ };
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+ };
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+
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+ __u32 last_mount; /* time_t */
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+
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+ __u16 first_bucket;
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+ union {
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+ __u16 njournal_buckets;
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+ __u16 keys;
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+ };
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+ __u64 d[SB_JOURNAL_BUCKETS]; /* journal buckets */
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+};
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+
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+static inline _Bool SB_IS_BDEV(const struct cache_sb *sb)
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+{
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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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+}
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+
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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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+
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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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+
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+/*
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+ * Magic numbers
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+ *
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+ * The various other data structures have their own magic numbers, which are
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+ * xored with the first part of the cache set's UUID
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+ */
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+
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+#define JSET_MAGIC 0x245235c1a3625032ULL
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+#define PSET_MAGIC 0x6750e15f87337f91ULL
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+#define BSET_MAGIC 0x90135c78b99e07f5ULL
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+
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+static inline __u64 jset_magic(struct cache_sb *sb)
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+{
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+ return sb->set_magic ^ JSET_MAGIC;
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+}
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+
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+static inline __u64 pset_magic(struct cache_sb *sb)
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+{
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+ return sb->set_magic ^ PSET_MAGIC;
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+}
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+
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+static inline __u64 bset_magic(struct cache_sb *sb)
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+{
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+ return sb->set_magic ^ BSET_MAGIC;
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+}
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+
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+/*
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+ * Journal
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+ *
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+ * On disk format for a journal entry:
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+ * seq is monotonically increasing; every journal entry has its own unique
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+ * sequence number.
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+ *
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+ * last_seq is the oldest journal entry that still has keys the btree hasn't
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+ * flushed to disk yet.
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+ *
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+ * version is for on disk format changes.
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+ */
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+
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+#define BCACHE_JSET_VERSION_UUIDv1 1
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+#define BCACHE_JSET_VERSION_UUID 1 /* Always latest UUID format */
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+#define BCACHE_JSET_VERSION 1
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+
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+struct jset {
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+ __u64 csum;
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+ __u64 magic;
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+ __u64 seq;
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+ __u32 version;
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+ __u32 keys;
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+
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+ __u64 last_seq;
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+
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+ BKEY_PADDED(uuid_bucket);
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+ BKEY_PADDED(btree_root);
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+ __u16 btree_level;
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+ __u16 pad[3];
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+
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+ __u64 prio_bucket[MAX_CACHES_PER_SET];
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+
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+ union {
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+ struct bkey start[0];
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+ __u64 d[0];
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+ };
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+};
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+
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+/* Bucket prios/gens */
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+
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+struct prio_set {
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+ __u64 csum;
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+ __u64 magic;
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+ __u64 seq;
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+ __u32 version;
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+ __u32 pad;
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+
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+ __u64 next_bucket;
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+
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+ struct bucket_disk {
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+ __u16 prio;
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+ __u8 gen;
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+ } __attribute((packed)) data[];
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+};
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+
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+/* UUIDS - per backing device/flash only volume metadata */
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+
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+struct uuid_entry {
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+ union {
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+ struct {
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+ __u8 uuid[16];
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+ __u8 label[32];
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+ __u32 first_reg;
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+ __u32 last_reg;
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+ __u32 invalidated;
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+
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+ __u32 flags;
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+ /* Size of flash only volumes */
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+ __u64 sectors;
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+ };
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+
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+ __u8 pad[128];
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+ };
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+};
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+
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+BITMASK(UUID_FLASH_ONLY, struct uuid_entry, flags, 0, 1);
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+
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+/* Btree nodes */
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+
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+/* Version 1: Seed pointer into btree node checksum
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+ */
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+#define BCACHE_BSET_CSUM 1
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+#define BCACHE_BSET_VERSION 1
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+
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+/*
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+ * Btree nodes
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+ *
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+ * On disk a btree node is a list/log of these; within each set the keys are
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+ * sorted
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+ */
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+struct bset {
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+ __u64 csum;
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+ __u64 magic;
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+ __u64 seq;
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+ __u32 version;
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+ __u32 keys;
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+
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+ union {
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+ struct bkey start[0];
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+ __u64 d[0];
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+ };
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+};
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+
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+/* OBSOLETE */
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+
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+/* UUIDS - per backing device/flash only volume metadata */
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+
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+struct uuid_entry_v0 {
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+ __u8 uuid[16];
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+ __u8 label[32];
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+ __u32 first_reg;
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+ __u32 last_reg;
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+ __u32 invalidated;
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+ __u32 pad;
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+};
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+
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+#endif /* _LINUX_BCACHE_H */
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Kent Overstreet