root/include/uapi/linux/bcache.h

/* [<][>][^][v][top][bottom][index][help] */

DEFINITIONS

This source file includes following definitions.
  1. KEY_FIELD
  2. SET_KEY_OFFSET
  3. PTR_FIELD
  4. bkey_bytes
  5. bkey_copy_key
  6. bkey_next
  7. bkey_idx
  8. SB_IS_BDEV
  9. jset_magic
  10. pset_magic
  11. bset_magic
#ifndef _LINUX_BCACHE_H
#define _LINUX_BCACHE_H

/*
 * Bcache on disk data structures
 */

#include <asm/types.h>

#define BITMASK(name, type, field, offset, size)                \
static inline __u64 name(const type *k)                         \
{ return (k->field >> offset) & ~(~0ULL << size); }             \
                                                                \
static inline void SET_##name(type *k, __u64 v)                 \
{                                                               \
        k->field &= ~(~(~0ULL << size) << offset);              \
        k->field |= (v & ~(~0ULL << size)) << offset;           \
}

/* Btree keys - all units are in sectors */

struct bkey {
        __u64   high;
        __u64   low;
        __u64   ptr[];
};

#define KEY_FIELD(name, field, offset, size)                            \
        BITMASK(name, struct bkey, field, offset, size)

#define PTR_FIELD(name, offset, size)                                   \
static inline __u64 name(const struct bkey *k, unsigned i)              \
{ return (k->ptr[i] >> offset) & ~(~0ULL << size); }                    \
                                                                        \
static inline void SET_##name(struct bkey *k, unsigned i, __u64 v)      \
{                                                                       \
        k->ptr[i] &= ~(~(~0ULL << size) << offset);                     \
        k->ptr[i] |= (v & ~(~0ULL << size)) << offset;                  \
}

#define KEY_SIZE_BITS           16
#define KEY_MAX_U64S            8

KEY_FIELD(KEY_PTRS,     high, 60, 3)
KEY_FIELD(HEADER_SIZE,  high, 58, 2)
KEY_FIELD(KEY_CSUM,     high, 56, 2)
KEY_FIELD(KEY_PINNED,   high, 55, 1)
KEY_FIELD(KEY_DIRTY,    high, 36, 1)

KEY_FIELD(KEY_SIZE,     high, 20, KEY_SIZE_BITS)
KEY_FIELD(KEY_INODE,    high, 0,  20)

/* Next time I change the on disk format, KEY_OFFSET() won't be 64 bits */

static inline __u64 KEY_OFFSET(const struct bkey *k)
{
        return k->low;
}

static inline void SET_KEY_OFFSET(struct bkey *k, __u64 v)
{
        k->low = v;
}

/*
 * The high bit being set is a relic from when we used it to do binary
 * searches - it told you where a key started. It's not used anymore,
 * and can probably be safely dropped.
 */
#define KEY(inode, offset, size)                                        \
((struct bkey) {                                                        \
        .high = (1ULL << 63) | ((__u64) (size) << 20) | (inode),        \
        .low = (offset)                                                 \
})

#define ZERO_KEY                        KEY(0, 0, 0)

#define MAX_KEY_INODE                   (~(~0 << 20))
#define MAX_KEY_OFFSET                  (~0ULL >> 1)
#define MAX_KEY                         KEY(MAX_KEY_INODE, MAX_KEY_OFFSET, 0)

#define KEY_START(k)                    (KEY_OFFSET(k) - KEY_SIZE(k))
#define START_KEY(k)                    KEY(KEY_INODE(k), KEY_START(k), 0)

#define PTR_DEV_BITS                    12

PTR_FIELD(PTR_DEV,                      51, PTR_DEV_BITS)
PTR_FIELD(PTR_OFFSET,                   8,  43)
PTR_FIELD(PTR_GEN,                      0,  8)

#define PTR_CHECK_DEV                   ((1 << PTR_DEV_BITS) - 1)

#define PTR(gen, offset, dev)                                           \
        ((((__u64) dev) << 51) | ((__u64) offset) << 8 | gen)

/* Bkey utility code */

static inline unsigned long bkey_u64s(const struct bkey *k)
{
        return (sizeof(struct bkey) / sizeof(__u64)) + KEY_PTRS(k);
}

static inline unsigned long bkey_bytes(const struct bkey *k)
{
        return bkey_u64s(k) * sizeof(__u64);
}

#define bkey_copy(_dest, _src)  memcpy(_dest, _src, bkey_bytes(_src))

static inline void bkey_copy_key(struct bkey *dest, const struct bkey *src)
{
        SET_KEY_INODE(dest, KEY_INODE(src));
        SET_KEY_OFFSET(dest, KEY_OFFSET(src));
}

static inline struct bkey *bkey_next(const struct bkey *k)
{
        __u64 *d = (void *) k;
        return (struct bkey *) (d + bkey_u64s(k));
}

static inline struct bkey *bkey_idx(const struct bkey *k, unsigned nr_keys)
{
        __u64 *d = (void *) k;
        return (struct bkey *) (d + nr_keys);
}
/* Enough for a key with 6 pointers */
#define BKEY_PAD                8

#define BKEY_PADDED(key)                                        \
        union { struct bkey key; __u64 key ## _pad[BKEY_PAD]; }

/* Superblock */

/* Version 0: Cache device
 * Version 1: Backing device
 * Version 2: Seed pointer into btree node checksum
 * Version 3: Cache device with new UUID format
 * Version 4: Backing device with data offset
 */
#define BCACHE_SB_VERSION_CDEV          0
#define BCACHE_SB_VERSION_BDEV          1
#define BCACHE_SB_VERSION_CDEV_WITH_UUID 3
#define BCACHE_SB_VERSION_BDEV_WITH_OFFSET 4
#define BCACHE_SB_MAX_VERSION           4

#define SB_SECTOR                       8
#define SB_SIZE                         4096
#define SB_LABEL_SIZE                   32
#define SB_JOURNAL_BUCKETS              256U
/* SB_JOURNAL_BUCKETS must be divisible by BITS_PER_LONG */
#define MAX_CACHES_PER_SET              8

#define BDEV_DATA_START_DEFAULT         16      /* sectors */

struct cache_sb {
        __u64                   csum;
        __u64                   offset; /* sector where this sb was written */
        __u64                   version;

        __u8                    magic[16];

        __u8                    uuid[16];
        union {
                __u8            set_uuid[16];
                __u64           set_magic;
        };
        __u8                    label[SB_LABEL_SIZE];

        __u64                   flags;
        __u64                   seq;
        __u64                   pad[8];

        union {
        struct {
                /* Cache devices */
                __u64           nbuckets;       /* device size */

                __u16           block_size;     /* sectors */
                __u16           bucket_size;    /* sectors */

                __u16           nr_in_set;
                __u16           nr_this_dev;
        };
        struct {
                /* Backing devices */
                __u64           data_offset;

                /*
                 * block_size from the cache device section is still used by
                 * backing devices, so don't add anything here until we fix
                 * things to not need it for backing devices anymore
                 */
        };
        };

        __u32                   last_mount;     /* time_t */

        __u16                   first_bucket;
        union {
                __u16           njournal_buckets;
                __u16           keys;
        };
        __u64                   d[SB_JOURNAL_BUCKETS];  /* journal buckets */
};

static inline _Bool SB_IS_BDEV(const struct cache_sb *sb)
{
        return sb->version == BCACHE_SB_VERSION_BDEV
                || sb->version == BCACHE_SB_VERSION_BDEV_WITH_OFFSET;
}

BITMASK(CACHE_SYNC,                     struct cache_sb, flags, 0, 1);
BITMASK(CACHE_DISCARD,                  struct cache_sb, flags, 1, 1);
BITMASK(CACHE_REPLACEMENT,              struct cache_sb, flags, 2, 3);
#define CACHE_REPLACEMENT_LRU           0U
#define CACHE_REPLACEMENT_FIFO          1U
#define CACHE_REPLACEMENT_RANDOM        2U

BITMASK(BDEV_CACHE_MODE,                struct cache_sb, flags, 0, 4);
#define CACHE_MODE_WRITETHROUGH         0U
#define CACHE_MODE_WRITEBACK            1U
#define CACHE_MODE_WRITEAROUND          2U
#define CACHE_MODE_NONE                 3U
BITMASK(BDEV_STATE,                     struct cache_sb, flags, 61, 2);
#define BDEV_STATE_NONE                 0U
#define BDEV_STATE_CLEAN                1U
#define BDEV_STATE_DIRTY                2U
#define BDEV_STATE_STALE                3U

/*
 * Magic numbers
 *
 * The various other data structures have their own magic numbers, which are
 * xored with the first part of the cache set's UUID
 */

#define JSET_MAGIC                      0x245235c1a3625032ULL
#define PSET_MAGIC                      0x6750e15f87337f91ULL
#define BSET_MAGIC                      0x90135c78b99e07f5ULL

static inline __u64 jset_magic(struct cache_sb *sb)
{
        return sb->set_magic ^ JSET_MAGIC;
}

static inline __u64 pset_magic(struct cache_sb *sb)
{
        return sb->set_magic ^ PSET_MAGIC;
}

static inline __u64 bset_magic(struct cache_sb *sb)
{
        return sb->set_magic ^ BSET_MAGIC;
}

/*
 * Journal
 *
 * On disk format for a journal entry:
 * seq is monotonically increasing; every journal entry has its own unique
 * sequence number.
 *
 * last_seq is the oldest journal entry that still has keys the btree hasn't
 * flushed to disk yet.
 *
 * version is for on disk format changes.
 */

#define BCACHE_JSET_VERSION_UUIDv1      1
#define BCACHE_JSET_VERSION_UUID        1       /* Always latest UUID format */
#define BCACHE_JSET_VERSION             1

struct jset {
        __u64                   csum;
        __u64                   magic;
        __u64                   seq;
        __u32                   version;
        __u32                   keys;

        __u64                   last_seq;

        BKEY_PADDED(uuid_bucket);
        BKEY_PADDED(btree_root);
        __u16                   btree_level;
        __u16                   pad[3];

        __u64                   prio_bucket[MAX_CACHES_PER_SET];

        union {
                struct bkey     start[0];
                __u64           d[0];
        };
};

/* Bucket prios/gens */

struct prio_set {
        __u64                   csum;
        __u64                   magic;
        __u64                   seq;
        __u32                   version;
        __u32                   pad;

        __u64                   next_bucket;

        struct bucket_disk {
                __u16           prio;
                __u8            gen;
        } __attribute((packed)) data[];
};

/* UUIDS - per backing device/flash only volume metadata */

struct uuid_entry {
        union {
                struct {
                        __u8    uuid[16];
                        __u8    label[32];
                        __u32   first_reg;
                        __u32   last_reg;
                        __u32   invalidated;

                        __u32   flags;
                        /* Size of flash only volumes */
                        __u64   sectors;
                };

                __u8            pad[128];
        };
};

BITMASK(UUID_FLASH_ONLY,        struct uuid_entry, flags, 0, 1);

/* Btree nodes */

/* Version 1: Seed pointer into btree node checksum
 */
#define BCACHE_BSET_CSUM                1
#define BCACHE_BSET_VERSION             1

/*
 * Btree nodes
 *
 * On disk a btree node is a list/log of these; within each set the keys are
 * sorted
 */
struct bset {
        __u64                   csum;
        __u64                   magic;
        __u64                   seq;
        __u32                   version;
        __u32                   keys;

        union {
                struct bkey     start[0];
                __u64           d[0];
        };
};

/* OBSOLETE */

/* UUIDS - per backing device/flash only volume metadata */

struct uuid_entry_v0 {
        __u8            uuid[16];
        __u8            label[32];
        __u32           first_reg;
        __u32           last_reg;
        __u32           invalidated;
        __u32           pad;
};

#endif /* _LINUX_BCACHE_H */
/* [<][>][^][v][top][bottom][index][help] */