bcachefs-tools/libbcachefs/bcachefs_format.h

#ifndef _LINUX_BCACHE_H
#define _LINUX_BCACHE_H

/*
 * Bcache on disk data structures
 */

#ifdef __cplusplus
typedef bool _Bool;
extern "C" {
#endif

#include <asm/types.h>
#include <asm/byteorder.h>
#include <linux/uuid.h>

#define LE32_BITMASK(name, type, field, offset, end)			\
static const unsigned	name##_OFFSET = offset;				\
static const unsigned	name##_BITS = (end - offset);			\
static const __u64	name##_MAX = (1ULL << (end - offset)) - 1;	\
									\
static inline __u64 name(const type *k)					\
{									\
	return (__le32_to_cpu(k->field) >> offset) &			\
		~(~0ULL << (end - offset));				\
}									\
									\
static inline void SET_##name(type *k, __u64 v)				\
{									\
	__u64 new = __le32_to_cpu(k->field);				\
									\
	new &= ~(~(~0ULL << (end - offset)) << offset);			\
	new |= (v & ~(~0ULL << (end - offset))) << offset;		\
	k->field = __cpu_to_le32(new);					\
}

#define LE64_BITMASK(name, type, field, offset, end)			\
static const unsigned	name##_OFFSET = offset;				\
static const unsigned	name##_BITS = (end - offset);			\
static const __u64	name##_MAX = (1ULL << (end - offset)) - 1;	\
									\
static inline __u64 name(const type *k)					\
{									\
	return (__le64_to_cpu(k->field) >> offset) &			\
		~(~0ULL << (end - offset));				\
}									\
									\
static inline void SET_##name(type *k, __u64 v)				\
{									\
	__u64 new = __le64_to_cpu(k->field);				\
									\
	new &= ~(~(~0ULL << (end - offset)) << offset);			\
	new |= (v & ~(~0ULL << (end - offset))) << offset;		\
	k->field = __cpu_to_le64(new);					\
}

struct bkey_format {
	__u8		key_u64s;
	__u8		nr_fields;
	/* One unused slot for now: */
	__u8		bits_per_field[6];
	__le64		field_offset[6];
};

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

struct bpos {
	/* Word order matches machine byte order */
#if defined(__LITTLE_ENDIAN)
	__u32		snapshot;
	__u64		offset;
	__u64		inode;
#elif defined(__BIG_ENDIAN)
	__u64		inode;
	__u64		offset;		/* Points to end of extent - sectors */
	__u32		snapshot;
#else
#error edit for your odd byteorder.
#endif
} __attribute__((packed, aligned(4)));

#define KEY_INODE_MAX			((__u64)~0ULL)
#define KEY_OFFSET_MAX			((__u64)~0ULL)
#define KEY_SNAPSHOT_MAX		((__u32)~0U)

static inline struct bpos POS(__u64 inode, __u64 offset)
{
	struct bpos ret;

	ret.inode	= inode;
	ret.offset	= offset;
	ret.snapshot	= 0;

	return ret;
}

#define POS_MIN				POS(0, 0)
#define POS_MAX				POS(KEY_INODE_MAX, KEY_OFFSET_MAX)

/* Empty placeholder struct, for container_of() */
struct bch_val {
	__u64		__nothing[0];
};

struct bversion {
#if defined(__LITTLE_ENDIAN)
	__u64		lo;
	__u32		hi;
#elif defined(__BIG_ENDIAN)
	__u32		hi;
	__u64		lo;
#endif
} __attribute__((packed, aligned(4)));

struct bkey {
	/* Size of combined key and value, in u64s */
	__u8		u64s;

	/* Format of key (0 for format local to btree node) */
#if defined(__LITTLE_ENDIAN_BITFIELD)
	__u8		format:7,
			needs_whiteout:1;
#elif defined (__BIG_ENDIAN_BITFIELD)
	__u8		needs_whiteout:1,
			format:7;
#else
#error edit for your odd byteorder.
#endif

	/* Type of the value */
	__u8		type;

#if defined(__LITTLE_ENDIAN)
	__u8		pad[1];

	struct bversion	version;
	__u32		size;		/* extent size, in sectors */
	struct bpos	p;
#elif defined(__BIG_ENDIAN)
	struct bpos	p;
	__u32		size;		/* extent size, in sectors */
	struct bversion	version;

	__u8		pad[1];
#endif
} __attribute__((packed, aligned(8)));

struct bkey_packed {
	__u64		_data[0];

	/* Size of combined key and value, in u64s */
	__u8		u64s;

	/* Format of key (0 for format local to btree node) */

	/*
	 * XXX: next incompat on disk format change, switch format and
	 * needs_whiteout - bkey_packed() will be cheaper if format is the high
	 * bits of the bitfield
	 */
#if defined(__LITTLE_ENDIAN_BITFIELD)
	__u8		format:7,
			needs_whiteout:1;
#elif defined (__BIG_ENDIAN_BITFIELD)
	__u8		needs_whiteout:1,
			format:7;
#endif

	/* Type of the value */
	__u8		type;
	__u8		key_start[0];

	/*
	 * We copy bkeys with struct assignment in various places, and while
	 * that shouldn't be done with packed bkeys we can't disallow it in C,
	 * and it's legal to cast a bkey to a bkey_packed  - so padding it out
	 * to the same size as struct bkey should hopefully be safest.
	 */
	__u8		pad[sizeof(struct bkey) - 3];
} __attribute__((packed, aligned(8)));

#define BKEY_U64s			(sizeof(struct bkey) / sizeof(__u64))
#define KEY_PACKED_BITS_START		24

#define KEY_SIZE_MAX			((__u32)~0U)

#define KEY_FORMAT_LOCAL_BTREE		0
#define KEY_FORMAT_CURRENT		1

enum bch_bkey_fields {
	BKEY_FIELD_INODE,
	BKEY_FIELD_OFFSET,
	BKEY_FIELD_SNAPSHOT,
	BKEY_FIELD_SIZE,
	BKEY_FIELD_VERSION_HI,
	BKEY_FIELD_VERSION_LO,
	BKEY_NR_FIELDS,
};

#define bkey_format_field(name, field)					\
	[BKEY_FIELD_##name] = (sizeof(((struct bkey *) NULL)->field) * 8)

#define BKEY_FORMAT_CURRENT						\
((struct bkey_format) {							\
	.key_u64s	= BKEY_U64s,					\
	.nr_fields	= BKEY_NR_FIELDS,				\
	.bits_per_field = {						\
		bkey_format_field(INODE,	p.inode),		\
		bkey_format_field(OFFSET,	p.offset),		\
		bkey_format_field(SNAPSHOT,	p.snapshot),		\
		bkey_format_field(SIZE,		size),			\
		bkey_format_field(VERSION_HI,	version.hi),		\
		bkey_format_field(VERSION_LO,	version.lo),		\
	},								\
})

/* bkey with inline value */
struct bkey_i {
	__u64			_data[0];

	union {
	struct {
		/* Size of combined key and value, in u64s */
		__u8		u64s;
	};
	struct {
		struct bkey	k;
		struct bch_val	v;
	};
	};
};

#ifndef __cplusplus

#define KEY(_inode, _offset, _size)					\
((struct bkey) {							\
	.u64s		= BKEY_U64s,					\
	.format		= KEY_FORMAT_CURRENT,				\
	.p		= POS(_inode, _offset),				\
	.size		= _size,					\
})

#else

static inline struct bkey KEY(__u64 inode, __u64 offset, __u64 size)
{
	struct bkey ret;

	memset(&ret, 0, sizeof(ret));
	ret.u64s	= BKEY_U64s;
	ret.format	= KEY_FORMAT_CURRENT;
	ret.p.inode	= inode;
	ret.p.offset	= offset;
	ret.size	= size;

	return ret;
}

#endif

static inline void bkey_init(struct bkey *k)
{
	*k = KEY(0, 0, 0);
}

#define bkey_bytes(_k)		((_k)->u64s * sizeof(__u64))

#define __BKEY_PADDED(key, pad)					\
	struct { struct bkey_i key; __u64 key ## _pad[pad]; }

#define BKEY_VAL_TYPE(name, nr)						\
struct bkey_i_##name {							\
	union {								\
		struct bkey		k;				\
		struct bkey_i		k_i;				\
	};								\
	struct bch_##name		v;				\
}

/*
 * - DELETED keys are used internally to mark keys that should be ignored but
 *   override keys in composition order.  Their version number is ignored.
 *
 * - DISCARDED keys indicate that the data is all 0s because it has been
 *   discarded. DISCARDs may have a version; if the version is nonzero the key
 *   will be persistent, otherwise the key will be dropped whenever the btree
 *   node is rewritten (like DELETED keys).
 *
 * - ERROR: any read of the data returns a read error, as the data was lost due
 *   to a failing device. Like DISCARDED keys, they can be removed (overridden)
 *   by new writes or cluster-wide GC. Node repair can also overwrite them with
 *   the same or a more recent version number, but not with an older version
 *   number.
*/
#define KEY_TYPE_DELETED		0
#define KEY_TYPE_DISCARD		1
#define KEY_TYPE_ERROR			2
#define KEY_TYPE_COOKIE			3
#define KEY_TYPE_PERSISTENT_DISCARD	4
#define KEY_TYPE_GENERIC_NR		128

struct bch_cookie {
	struct bch_val		v;
	__le64			cookie;
};
BKEY_VAL_TYPE(cookie,		KEY_TYPE_COOKIE);

/* Extents */

/*
 * In extent bkeys, the value is a list of pointers (bch_extent_ptr), optionally
 * preceded by checksum/compression information (bch_extent_crc32 or
 * bch_extent_crc64).
 *
 * One major determining factor in the format of extents is how we handle and
 * represent extents that have been partially overwritten and thus trimmed:
 *
 * If an extent is not checksummed or compressed, when the extent is trimmed we
 * don't have to remember the extent we originally allocated and wrote: we can
 * merely adjust ptr->offset to point to the start of the start of the data that
 * is currently live. The size field in struct bkey records the current (live)
 * size of the extent, and is also used to mean "size of region on disk that we
 * point to" in this case.
 *
 * Thus an extent that is not checksummed or compressed will consist only of a
 * list of bch_extent_ptrs, with none of the fields in
 * bch_extent_crc32/bch_extent_crc64.
 *
 * When an extent is checksummed or compressed, it's not possible to read only
 * the data that is currently live: we have to read the entire extent that was
 * originally written, and then return only the part of the extent that is
 * currently live.
 *
 * Thus, in addition to the current size of the extent in struct bkey, we need
 * to store the size of the originally allocated space - this is the
 * compressed_size and uncompressed_size fields in bch_extent_crc32/64. Also,
 * when the extent is trimmed, instead of modifying the offset field of the
 * pointer, we keep a second smaller offset field - "offset into the original
 * extent of the currently live region".
 *
 * The other major determining factor is replication and data migration:
 *
 * Each pointer may have its own bch_extent_crc32/64. When doing a replicated
 * write, we will initially write all the replicas in the same format, with the
 * same checksum type and compression format - however, when copygc runs later (or
 * tiering/cache promotion, anything that moves data), it is not in general
 * going to rewrite all the pointers at once - one of the replicas may be in a
 * bucket on one device that has very little fragmentation while another lives
 * in a bucket that has become heavily fragmented, and thus is being rewritten
 * sooner than the rest.
 *
 * Thus it will only move a subset of the pointers (or in the case of
 * tiering/cache promotion perhaps add a single pointer without dropping any
 * current pointers), and if the extent has been partially overwritten it must
 * write only the currently live portion (or copygc would not be able to reduce
 * fragmentation!) - which necessitates a different bch_extent_crc format for
 * the new pointer.
 *
 * But in the interests of space efficiency, we don't want to store one
 * bch_extent_crc for each pointer if we don't have to.
 *
 * Thus, a bch_extent consists of bch_extent_crc32s, bch_extent_crc64s, and
 * bch_extent_ptrs appended arbitrarily one after the other. We determine the
 * type of a given entry with a scheme similar to utf8 (except we're encoding a
 * type, not a size), encoding the type in the position of the first set bit:
 *
 * bch_extent_crc32	- 0b1
 * bch_extent_ptr	- 0b10
 * bch_extent_crc64	- 0b100
 *
 * We do it this way because bch_extent_crc32 is _very_ constrained on bits (and
 * bch_extent_crc64 is the least constrained).
 *
 * Then, each bch_extent_crc32/64 applies to the pointers that follow after it,
 * until the next bch_extent_crc32/64.
 *
 * If there are no bch_extent_crcs preceding a bch_extent_ptr, then that pointer
 * is neither checksummed nor compressed.
 */

/* 128 bits, sufficient for cryptographic MACs: */
struct bch_csum {
	__le64			lo;
	__le64			hi;
} __attribute__((packed, aligned(8)));

#define BCH_CSUM_NONE			0U
#define BCH_CSUM_CRC32C			1U
#define BCH_CSUM_CRC64			2U
#define BCH_CSUM_CHACHA20_POLY1305_80	3U
#define BCH_CSUM_CHACHA20_POLY1305_128	4U
#define BCH_CSUM_NR			5U

static inline _Bool bch2_csum_type_is_encryption(unsigned type)
{
	switch (type) {
	case BCH_CSUM_CHACHA20_POLY1305_80:
	case BCH_CSUM_CHACHA20_POLY1305_128:
		return true;
	default:
		return false;
	}
}

enum bch_extent_entry_type {
	BCH_EXTENT_ENTRY_ptr		= 0,
	BCH_EXTENT_ENTRY_crc32		= 1,
	BCH_EXTENT_ENTRY_crc64		= 2,
	BCH_EXTENT_ENTRY_crc128		= 3,
};

#define BCH_EXTENT_ENTRY_MAX		4

/* Compressed/uncompressed size are stored biased by 1: */
struct bch_extent_crc32 {
#if defined(__LITTLE_ENDIAN_BITFIELD)
	__u32			type:2,
				_compressed_size:7,
				_uncompressed_size:7,
				offset:7,
				_unused:1,
				csum_type:4,
				compression_type:4;
	__u32			csum;
#elif defined (__BIG_ENDIAN_BITFIELD)
	__u32			csum;
	__u32			compression_type:4,
				csum_type:4,
				_unused:1,
				offset:7,
				_uncompressed_size:7,
				_compressed_size:7,
				type:2;
#endif
} __attribute__((packed, aligned(8)));

#define CRC32_SIZE_MAX		(1U << 7)
#define CRC32_NONCE_MAX		0

struct bch_extent_crc64 {
#if defined(__LITTLE_ENDIAN_BITFIELD)
	__u64			type:3,
				_compressed_size:9,
				_uncompressed_size:9,
				offset:9,
				nonce:10,
				csum_type:4,
				compression_type:4,
				csum_hi:16;
#elif defined (__BIG_ENDIAN_BITFIELD)
	__u64			csum_hi:16,
				compression_type:4,
				csum_type:4,
				nonce:10,
				offset:9,
				_uncompressed_size:9,
				_compressed_size:9,
				type:3;
#endif
	__u64			csum_lo;
} __attribute__((packed, aligned(8)));

#define CRC64_SIZE_MAX		(1U << 9)
#define CRC64_NONCE_MAX		((1U << 10) - 1)

struct bch_extent_crc128 {
#if defined(__LITTLE_ENDIAN_BITFIELD)
	__u64			type:4,
				_compressed_size:13,
				_uncompressed_size:13,
				offset:13,
				nonce:13,
				csum_type:4,
				compression_type:4;
#elif defined (__BIG_ENDIAN_BITFIELD)
	__u64			compression_type:4,
				csum_type:4,
				nonce:14,
				offset:13,
				_uncompressed_size:13,
				_compressed_size:13,
				type:3;
#endif
	struct bch_csum		csum;
} __attribute__((packed, aligned(8)));

#define CRC128_SIZE_MAX		(1U << 13)
#define CRC128_NONCE_MAX	((1U << 13) - 1)

/*
 * Max size of an extent that may require bouncing to read or write
 * (checksummed, compressed): 64k
 */
#define BCH_ENCODED_EXTENT_MAX	128U

/*
 * @reservation - pointer hasn't been written to, just reserved
 */
struct bch_extent_ptr {
#if defined(__LITTLE_ENDIAN_BITFIELD)
	__u64			type:1,
				cached:1,
				erasure_coded:1,
				reservation:1,
				offset:44, /* 8 petabytes */
				dev:8,
				gen:8;
#elif defined (__BIG_ENDIAN_BITFIELD)
	__u64			gen:8,
				dev:8,
				offset:44,
				reservation:1,
				erasure_coded:1,
				cached:1,
				type:1;
#endif
} __attribute__((packed, aligned(8)));

struct bch_extent_reservation {
#if defined(__LITTLE_ENDIAN_BITFIELD)
	__u64			type:5,
				unused:23,
				replicas:4,
				generation:32;
#elif defined (__BIG_ENDIAN_BITFIELD)
	__u64			generation:32,
				replicas:4,
				unused:23,
				type:5;
#endif
};

union bch_extent_entry {
#if defined(__LITTLE_ENDIAN) ||  __BITS_PER_LONG == 64
	unsigned long			type;
#elif __BITS_PER_LONG == 32
	struct {
		unsigned long		pad;
		unsigned long		type;
	};
#else
#error edit for your odd byteorder.
#endif
	struct bch_extent_crc32		crc32;
	struct bch_extent_crc64		crc64;
	struct bch_extent_crc128	crc128;
	struct bch_extent_ptr		ptr;
};

enum {
	BCH_EXTENT		= 128,

	/*
	 * This is kind of a hack, we're overloading the type for a boolean that
	 * really should be part of the value - BCH_EXTENT and BCH_EXTENT_CACHED
	 * have the same value type:
	 */
	BCH_EXTENT_CACHED	= 129,

	/*
	 * Persistent reservation:
	 */
	BCH_RESERVATION		= 130,
};

struct bch_extent {
	struct bch_val		v;

	union bch_extent_entry	start[0];
	__u64			_data[0];
} __attribute__((packed, aligned(8)));
BKEY_VAL_TYPE(extent,		BCH_EXTENT);

struct bch_reservation {
	struct bch_val		v;

	__le32			generation;
	__u8			nr_replicas;
	__u8			pad[3];
} __attribute__((packed, aligned(8)));
BKEY_VAL_TYPE(reservation,	BCH_RESERVATION);

/* Maximum size (in u64s) a single pointer could be: */
#define BKEY_EXTENT_PTR_U64s_MAX\
	((sizeof(struct bch_extent_crc128) +			\
	  sizeof(struct bch_extent_ptr)) / sizeof(u64))

/* Maximum possible size of an entire extent value: */
/* There's a hack in the keylist code that needs to be fixed.. */
#define BKEY_EXTENT_VAL_U64s_MAX				\
	(BKEY_EXTENT_PTR_U64s_MAX * BCH_REPLICAS_MAX)

/* * Maximum possible size of an entire extent, key + value: */
#define BKEY_EXTENT_U64s_MAX		(BKEY_U64s + BKEY_EXTENT_VAL_U64s_MAX)

/* Btree pointers don't carry around checksums: */
#define BKEY_BTREE_PTR_VAL_U64s_MAX				\
	((sizeof(struct bch_extent_ptr)) / sizeof(u64) * BCH_REPLICAS_MAX)
#define BKEY_BTREE_PTR_U64s_MAX					\
	(BKEY_U64s + BKEY_BTREE_PTR_VAL_U64s_MAX)

/* Inodes */

#define BLOCKDEV_INODE_MAX	4096

#define BCACHE_ROOT_INO		4096

enum bch_inode_types {
	BCH_INODE_FS		= 128,
	BCH_INODE_BLOCKDEV	= 129,
};

struct bch_inode {
	struct bch_val		v;

	__le64			i_hash_seed;
	__le32			i_flags;
	__le16			i_mode;
	__u8			fields[0];
} __attribute__((packed));
BKEY_VAL_TYPE(inode,		BCH_INODE_FS);

#define BCH_INODE_FIELDS()				\
	BCH_INODE_FIELD(i_atime,	64)		\
	BCH_INODE_FIELD(i_ctime,	64)		\
	BCH_INODE_FIELD(i_mtime,	64)		\
	BCH_INODE_FIELD(i_otime,	64)		\
	BCH_INODE_FIELD(i_size,		64)		\
	BCH_INODE_FIELD(i_sectors,	64)		\
	BCH_INODE_FIELD(i_uid,		32)		\
	BCH_INODE_FIELD(i_gid,		32)		\
	BCH_INODE_FIELD(i_nlink,	32)		\
	BCH_INODE_FIELD(i_generation,	32)		\
	BCH_INODE_FIELD(i_dev,		32)

enum {
	/*
	 * User flags (get/settable with FS_IOC_*FLAGS, correspond to FS_*_FL
	 * flags)
	 */
	__BCH_INODE_SYNC	= 0,
	__BCH_INODE_IMMUTABLE	= 1,
	__BCH_INODE_APPEND	= 2,
	__BCH_INODE_NODUMP	= 3,
	__BCH_INODE_NOATIME	= 4,

	__BCH_INODE_I_SIZE_DIRTY= 5,
	__BCH_INODE_I_SECTORS_DIRTY= 6,

	/* not implemented yet: */
	__BCH_INODE_HAS_XATTRS	= 7, /* has xattrs in xattr btree */

	/* bits 20+ reserved for packed fields below: */
};

#define BCH_INODE_SYNC		(1 << __BCH_INODE_SYNC)
#define BCH_INODE_IMMUTABLE	(1 << __BCH_INODE_IMMUTABLE)
#define BCH_INODE_APPEND	(1 << __BCH_INODE_APPEND)
#define BCH_INODE_NODUMP	(1 << __BCH_INODE_NODUMP)
#define BCH_INODE_NOATIME	(1 << __BCH_INODE_NOATIME)
#define BCH_INODE_I_SIZE_DIRTY	(1 << __BCH_INODE_I_SIZE_DIRTY)
#define BCH_INODE_I_SECTORS_DIRTY (1 << __BCH_INODE_I_SECTORS_DIRTY)
#define BCH_INODE_HAS_XATTRS	(1 << __BCH_INODE_HAS_XATTRS)

LE32_BITMASK(INODE_STR_HASH,	struct bch_inode, i_flags, 20, 24);
LE32_BITMASK(INODE_NR_FIELDS,	struct bch_inode, i_flags, 24, 32);

struct bch_inode_blockdev {
	struct bch_val		v;

	__le64			i_size;
	__le64			i_flags;

	/* Seconds: */
	__le64			i_ctime;
	__le64			i_mtime;

	uuid_le			i_uuid;
	__u8			i_label[32];
} __attribute__((packed, aligned(8)));
BKEY_VAL_TYPE(inode_blockdev,	BCH_INODE_BLOCKDEV);

/* Thin provisioned volume, or cache for another block device? */
LE64_BITMASK(CACHED_DEV,	struct bch_inode_blockdev, i_flags, 0,  1)

/* Dirents */

/*
 * Dirents (and xattrs) have to implement string lookups; since our b-tree
 * doesn't support arbitrary length strings for the key, we instead index by a
 * 64 bit hash (currently truncated sha1) of the string, stored in the offset
 * field of the key - using linear probing to resolve hash collisions. This also
 * provides us with the readdir cookie posix requires.
 *
 * Linear probing requires us to use whiteouts for deletions, in the event of a
 * collision:
 */

enum {
	BCH_DIRENT		= 128,
	BCH_DIRENT_WHITEOUT	= 129,
};

struct bch_dirent {
	struct bch_val		v;

	/* Target inode number: */
	__le64			d_inum;

	/*
	 * Copy of mode bits 12-15 from the target inode - so userspace can get
	 * the filetype without having to do a stat()
	 */
	__u8			d_type;

	__u8			d_name[];
} __attribute__((packed));
BKEY_VAL_TYPE(dirent,		BCH_DIRENT);

/* Xattrs */

enum {
	BCH_XATTR		= 128,
	BCH_XATTR_WHITEOUT	= 129,
};

#define BCH_XATTR_INDEX_USER			0
#define BCH_XATTR_INDEX_POSIX_ACL_ACCESS	1
#define BCH_XATTR_INDEX_POSIX_ACL_DEFAULT	2
#define BCH_XATTR_INDEX_TRUSTED			3
#define BCH_XATTR_INDEX_SECURITY	        4

struct bch_xattr {
	struct bch_val		v;
	__u8			x_type;
	__u8			x_name_len;
	__le16			x_val_len;
	__u8			x_name[];
} __attribute__((packed));
BKEY_VAL_TYPE(xattr,		BCH_XATTR);

/* 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
 * Version 5: All the incompat changes
 * Version 6: Cache device UUIDs all in superblock, another incompat bset change
 * Version 7: Encryption (expanded checksum fields), other random things
 */
#define BCACHE_SB_VERSION_CDEV_V0	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_VERSION_CDEV_V2	5
#define BCACHE_SB_VERSION_CDEV_V3	6
#define BCACHE_SB_VERSION_CDEV_V4	7
#define BCACHE_SB_VERSION_CDEV		7
#define BCACHE_SB_MAX_VERSION		7

#define BCH_SB_SECTOR			8
#define BCH_SB_LABEL_SIZE		32
#define BCH_SB_MEMBERS_MAX		64 /* XXX kill */

struct bch_member {
	uuid_le			uuid;
	__le64			nbuckets;	/* device size */
	__le16			first_bucket;   /* index of first bucket used */
	__le16			bucket_size;	/* sectors */
	__le32			pad;
	__le64			last_mount;	/* time_t */

	__le64			flags[2];
};

LE64_BITMASK(BCH_MEMBER_STATE,		struct bch_member, flags[0],  0,  4)
LE64_BITMASK(BCH_MEMBER_TIER,		struct bch_member, flags[0],  4,  8)
LE64_BITMASK(BCH_MEMBER_HAS_METADATA,	struct bch_member, flags[0],  8,  9)
LE64_BITMASK(BCH_MEMBER_HAS_DATA,	struct bch_member, flags[0],  9, 10)
LE64_BITMASK(BCH_MEMBER_REPLACEMENT,	struct bch_member, flags[0], 10, 14)
LE64_BITMASK(BCH_MEMBER_DISCARD,	struct bch_member, flags[0], 14, 15);

#if 0
LE64_BITMASK(BCH_MEMBER_NR_READ_ERRORS,	struct bch_member, flags[1], 0,  20);
LE64_BITMASK(BCH_MEMBER_NR_WRITE_ERRORS,struct bch_member, flags[1], 20, 40);
#endif

enum bch_member_state {
	BCH_MEMBER_STATE_RW		= 0,
	BCH_MEMBER_STATE_RO		= 1,
	BCH_MEMBER_STATE_FAILED		= 2,
	BCH_MEMBER_STATE_SPARE		= 3,
	BCH_MEMBER_STATE_NR		= 4,
};

#define BCH_TIER_MAX			4U

enum cache_replacement {
	CACHE_REPLACEMENT_LRU		= 0,
	CACHE_REPLACEMENT_FIFO		= 1,
	CACHE_REPLACEMENT_RANDOM	= 2,
	CACHE_REPLACEMENT_NR		= 3,
};

struct bch_sb_layout {
	uuid_le			magic;	/* bcachefs superblock UUID */
	__u8			layout_type;
	__u8			sb_max_size_bits; /* base 2 of 512 byte sectors */
	__u8			nr_superblocks;
	__u8			pad[5];
	__u64			sb_offset[61];
} __attribute__((packed));

#define BCH_SB_LAYOUT_SECTOR	7

struct bch_sb_field {
	__u64			_data[0];
	__le32			u64s;
	__le32			type;
};

enum bch_sb_field_type {
	BCH_SB_FIELD_journal	= 0,
	BCH_SB_FIELD_members	= 1,
	BCH_SB_FIELD_crypt	= 2,
	BCH_SB_FIELD_NR		= 3,
};

struct bch_sb_field_journal {
	struct bch_sb_field	field;
	__le64			buckets[0];
};

struct bch_sb_field_members {
	struct bch_sb_field	field;
	struct bch_member	members[0];
};

/* Crypto: */

struct nonce {
	__le32			d[4];
};

struct bch_key {
	__le64			key[4];
};

#define BCH_KEY_MAGIC					\
	(((u64) 'b' <<  0)|((u64) 'c' <<  8)|		\
	 ((u64) 'h' << 16)|((u64) '*' << 24)|		\
	 ((u64) '*' << 32)|((u64) 'k' << 40)|		\
	 ((u64) 'e' << 48)|((u64) 'y' << 56))

struct bch_encrypted_key {
	__le64			magic;
	struct bch_key		key;
};

/*
 * If this field is present in the superblock, it stores an encryption key which
 * is used encrypt all other data/metadata. The key will normally be encrypted
 * with the key userspace provides, but if encryption has been turned off we'll
 * just store the master key unencrypted in the superblock so we can access the
 * previously encrypted data.
 */
struct bch_sb_field_crypt {
	struct bch_sb_field	field;

	__le64			flags;
	__le64			kdf_flags;
	struct bch_encrypted_key key;
};

LE64_BITMASK(BCH_CRYPT_KDF_TYPE,	struct bch_sb_field_crypt, flags, 0, 4);

enum bch_kdf_types {
	BCH_KDF_SCRYPT		= 0,
	BCH_KDF_NR		= 1,
};

/* stored as base 2 log of scrypt params: */
LE64_BITMASK(BCH_KDF_SCRYPT_N,	struct bch_sb_field_crypt, kdf_flags,  0, 16);
LE64_BITMASK(BCH_KDF_SCRYPT_R,	struct bch_sb_field_crypt, kdf_flags, 16, 32);
LE64_BITMASK(BCH_KDF_SCRYPT_P,	struct bch_sb_field_crypt, kdf_flags, 32, 48);

struct bch_sb_field_replication {
	struct bch_sb_field	field;
};

/*
 * @offset	- sector where this sb was written
 * @version	- on disk format version
 * @magic	- identifies as a bcachefs superblock (BCACHE_MAGIC)
 * @seq		- incremented each time superblock is written
 * @uuid	- used for generating various magic numbers and identifying
 *                member devices, never changes
 * @user_uuid	- user visible UUID, may be changed
 * @label	- filesystem label
 * @seq		- identifies most recent superblock, incremented each time
 *		  superblock is written
 * @features	- enabled incompatible features
 */
struct bch_sb {
	struct bch_csum		csum;
	__le64			version;
	uuid_le			magic;
	uuid_le			uuid;
	uuid_le			user_uuid;
	__u8			label[BCH_SB_LABEL_SIZE];
	__le64			offset;
	__le64			seq;

	__le16			block_size;
	__u8			dev_idx;
	__u8			nr_devices;
	__le32			u64s;

	__le64			time_base_lo;
	__le32			time_base_hi;
	__le32			time_precision;

	__le64			flags[8];
	__le64			features[2];
	__le64			compat[2];

	struct bch_sb_layout	layout;

	union {
		struct bch_sb_field start[0];
		__le64		_data[0];
	};
} __attribute__((packed, aligned(8)));

/*
 * Flags:
 * BCH_SB_INITALIZED	- set on first mount
 * BCH_SB_CLEAN		- did we shut down cleanly? Just a hint, doesn't affect
 *			  behaviour of mount/recovery path:
 * BCH_SB_INODE_32BIT	- limit inode numbers to 32 bits
 * BCH_SB_128_BIT_MACS	- 128 bit macs instead of 80
 * BCH_SB_ENCRYPTION_TYPE - if nonzero encryption is enabled; overrides
 *			   DATA/META_CSUM_TYPE. Also indicates encryption
 *			   algorithm in use, if/when we get more than one
 */

LE64_BITMASK(BCH_SB_INITIALIZED,	struct bch_sb, flags[0],  0,  1);
LE64_BITMASK(BCH_SB_CLEAN,		struct bch_sb, flags[0],  1,  2);
LE64_BITMASK(BCH_SB_CSUM_TYPE,		struct bch_sb, flags[0],  2,  8);
LE64_BITMASK(BCH_SB_ERROR_ACTION,	struct bch_sb, flags[0],  8, 12);

LE64_BITMASK(BCH_SB_BTREE_NODE_SIZE,	struct bch_sb, flags[0], 12, 28);

LE64_BITMASK(BCH_SB_GC_RESERVE,		struct bch_sb, flags[0], 28, 33);
LE64_BITMASK(BCH_SB_ROOT_RESERVE,	struct bch_sb, flags[0], 33, 40);

LE64_BITMASK(BCH_SB_META_CSUM_TYPE,	struct bch_sb, flags[0], 40, 44);
LE64_BITMASK(BCH_SB_DATA_CSUM_TYPE,	struct bch_sb, flags[0], 44, 48);

LE64_BITMASK(BCH_SB_META_REPLICAS_WANT,	struct bch_sb, flags[0], 48, 52);
LE64_BITMASK(BCH_SB_DATA_REPLICAS_WANT,	struct bch_sb, flags[0], 52, 56);

LE64_BITMASK(BCH_SB_META_REPLICAS_HAVE,	struct bch_sb, flags[0], 56, 60);
LE64_BITMASK(BCH_SB_DATA_REPLICAS_HAVE,	struct bch_sb, flags[0], 60, 64);

LE64_BITMASK(BCH_SB_STR_HASH_TYPE,	struct bch_sb, flags[1],  0,  4);
LE64_BITMASK(BCH_SB_COMPRESSION_TYPE,	struct bch_sb, flags[1],  4,  8);
LE64_BITMASK(BCH_SB_INODE_32BIT,	struct bch_sb, flags[1],  8,  9);

LE64_BITMASK(BCH_SB_128_BIT_MACS,	struct bch_sb, flags[1],  9, 10);
LE64_BITMASK(BCH_SB_ENCRYPTION_TYPE,	struct bch_sb, flags[1], 10, 14);
LE64_BITMASK(BCH_SB_JOURNAL_ENTRY_SIZE,	struct bch_sb, flags[1], 14, 20);

LE64_BITMASK(BCH_SB_META_REPLICAS_REQ,	struct bch_sb, flags[1], 20, 24);
LE64_BITMASK(BCH_SB_DATA_REPLICAS_REQ,	struct bch_sb, flags[1], 24, 28);

/* Features: */
enum bch_sb_features {
	BCH_FEATURE_LZ4			= 0,
	BCH_FEATURE_GZIP		= 1,
};

/* options: */

#define BCH_REPLICAS_MAX		4U

#if 0
#define BCH_ERROR_ACTIONS()					\
	x(BCH_ON_ERROR_CONTINUE,	0, "continue")		\
	x(BCH_ON_ERROR_RO,		1, "remount-ro")	\
	x(BCH_ON_ERROR_PANIC,		2, "panic")		\
	x(BCH_NR_ERROR_ACTIONS,		3, NULL)

enum bch_error_actions {
#define x(_opt, _nr, _str)	_opt = _nr,
	BCH_ERROR_ACTIONS()
#undef x
};
#endif

enum bch_error_actions {
	BCH_ON_ERROR_CONTINUE		= 0,
	BCH_ON_ERROR_RO			= 1,
	BCH_ON_ERROR_PANIC		= 2,
	BCH_NR_ERROR_ACTIONS		= 3,
};

enum bch_csum_opts {
	BCH_CSUM_OPT_NONE		= 0,
	BCH_CSUM_OPT_CRC32C		= 1,
	BCH_CSUM_OPT_CRC64		= 2,
	BCH_CSUM_OPT_NR			= 3,
};

enum bch_str_hash_opts {
	BCH_STR_HASH_CRC32C		= 0,
	BCH_STR_HASH_CRC64		= 1,
	BCH_STR_HASH_SIPHASH		= 2,
	BCH_STR_HASH_NR			= 3,
};

enum bch_compression_opts {
	BCH_COMPRESSION_NONE		= 0,
	BCH_COMPRESSION_LZ4		= 1,
	BCH_COMPRESSION_GZIP		= 2,
	BCH_COMPRESSION_NR		= 3,
};

/* backing device specific stuff: */

struct backingdev_sb {
	__le64			csum;
	__le64			offset;	/* sector where this sb was written */
	__le64			version; /* of on disk format */

	uuid_le			magic;	/* bcachefs superblock UUID */

	uuid_le			disk_uuid;

	/*
	 * Internal cache set UUID - xored with various magic numbers and thus
	 * must never change:
	 */
	union {
		uuid_le		set_uuid;
		__le64		set_magic;
	};
	__u8			label[BCH_SB_LABEL_SIZE];

	__le64			flags;

	/* Incremented each time superblock is written: */
	__le64			seq;

	/*
	 * User visible UUID for identifying the cache set the user is allowed
	 * to change:
	 *
	 * XXX hooked up?
	 */
	uuid_le			user_uuid;
	__le64			pad1[6];

	__le64			data_offset;
	__le16			block_size;	/* sectors */
	__le16			pad2[3];

	__le32			last_mount;	/* time_t */
	__le16			pad3;
	/* size of variable length portion - always 0 for backingdev superblock */
	__le16			u64s;
	__u64			_data[0];
};

LE64_BITMASK(BDEV_CACHE_MODE,		struct backingdev_sb, flags, 0, 4);
#define CACHE_MODE_WRITETHROUGH		0U
#define CACHE_MODE_WRITEBACK		1U
#define CACHE_MODE_WRITEAROUND		2U
#define CACHE_MODE_NONE			3U

LE64_BITMASK(BDEV_STATE,		struct backingdev_sb, flags, 61, 63);
#define BDEV_STATE_NONE			0U
#define BDEV_STATE_CLEAN		1U
#define BDEV_STATE_DIRTY		2U
#define BDEV_STATE_STALE		3U

#define BDEV_DATA_START_DEFAULT		16	/* sectors */

static inline _Bool __SB_IS_BDEV(__u64 version)
{
	return version == BCACHE_SB_VERSION_BDEV
		|| version == BCACHE_SB_VERSION_BDEV_WITH_OFFSET;
}

static inline _Bool SB_IS_BDEV(const struct bch_sb *sb)
{
	return __SB_IS_BDEV(sb->version);
}

/*
 * 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 BCACHE_MAGIC							\
	UUID_LE(0xf67385c6, 0x1a4e, 0xca45,				\
		0x82, 0x65, 0xf5, 0x7f, 0x48, 0xba, 0x6d, 0x81)

#define BCACHE_STATFS_MAGIC		0xca451a4e

#define JSET_MAGIC		__cpu_to_le64(0x245235c1a3625032ULL)
#define PSET_MAGIC		__cpu_to_le64(0x6750e15f87337f91ULL)
#define BSET_MAGIC		__cpu_to_le64(0x90135c78b99e07f5ULL)

static inline __le64 __bch2_sb_magic(struct bch_sb *sb)
{
	__le64 ret;
	memcpy(&ret, &sb->uuid, sizeof(ret));
	return ret;
}

static inline __u64 __jset_magic(struct bch_sb *sb)
{
	return __le64_to_cpu(__bch2_sb_magic(sb) ^ JSET_MAGIC);
}

static inline __u64 __pset_magic(struct bch_sb *sb)
{
	return __le64_to_cpu(__bch2_sb_magic(sb) ^ PSET_MAGIC);
}

static inline __u64 __bset_magic(struct bch_sb *sb)
{
	return __le64_to_cpu(__bch2_sb_magic(sb) ^ BSET_MAGIC);
}

/* Journal */

#define BCACHE_JSET_VERSION_UUIDv1	1
#define BCACHE_JSET_VERSION_UUID	1	/* Always latest UUID format */
#define BCACHE_JSET_VERSION_JKEYS	2
#define BCACHE_JSET_VERSION		2

struct jset_entry {
	__le16			u64s;
	__u8			btree_id;
	__u8			level;
	__le32			flags; /* designates what this jset holds */

	union {
		struct bkey_i	start[0];
		__u64		_data[0];
	};
};

#define JSET_KEYS_U64s	(sizeof(struct jset_entry) / sizeof(__u64))

LE32_BITMASK(JOURNAL_ENTRY_TYPE,	struct jset_entry, flags, 0, 8);
enum {
	JOURNAL_ENTRY_BTREE_KEYS	= 0,
	JOURNAL_ENTRY_BTREE_ROOT	= 1,
	JOURNAL_ENTRY_PRIO_PTRS		= 2,

	/*
	 * Journal sequence numbers can be blacklisted: bsets record the max
	 * sequence number of all the journal entries they contain updates for,
	 * so that on recovery we can ignore those bsets that contain index
	 * updates newer that what made it into the journal.
	 *
	 * This means that we can't reuse that journal_seq - we have to skip it,
	 * and then record that we skipped it so that the next time we crash and
	 * recover we don't think there was a missing journal entry.
	 */
	JOURNAL_ENTRY_JOURNAL_SEQ_BLACKLISTED = 3,
};

/*
 * 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.
 */
struct jset {
	struct bch_csum		csum;

	__le64			magic;
	__le64			seq;
	__le32			version;
	__le32			flags;

	__le32			u64s; /* size of d[] in u64s */

	__u8			encrypted_start[0];

	__le16			read_clock;
	__le16			write_clock;

	/* Sequence number of oldest dirty journal entry */
	__le64			last_seq;


	union {
		struct jset_entry start[0];
		__u64		_data[0];
	};
} __attribute__((packed));

LE32_BITMASK(JSET_CSUM_TYPE,	struct jset, flags, 0, 4);
LE32_BITMASK(JSET_BIG_ENDIAN,	struct jset, flags, 4, 5);

#define BCH_JOURNAL_BUCKETS_MIN		20

/* Bucket prios/gens */

struct prio_set {
	struct bch_csum		csum;

	__le64			magic;
	__le32			nonce[3];
	__le16			version;
	__le16			flags;

	__u8			encrypted_start[0];

	__le64			next_bucket;

	struct bucket_disk {
		__le16		read_prio;
		__le16		write_prio;
		__u8		gen;
	} __attribute__((packed)) data[];
} __attribute__((packed));

LE32_BITMASK(PSET_CSUM_TYPE,	struct prio_set, flags, 0, 4);

/* Btree: */

#define DEFINE_BCH_BTREE_IDS()					\
	DEF_BTREE_ID(EXTENTS, 0, "extents")			\
	DEF_BTREE_ID(INODES,  1, "inodes")			\
	DEF_BTREE_ID(DIRENTS, 2, "dirents")			\
	DEF_BTREE_ID(XATTRS,  3, "xattrs")

#define DEF_BTREE_ID(kwd, val, name) BTREE_ID_##kwd = val,

enum btree_id {
	DEFINE_BCH_BTREE_IDS()
	BTREE_ID_NR
};

#undef DEF_BTREE_ID

#define BTREE_MAX_DEPTH		4U

/* Btree nodes */

/* Version 1: Seed pointer into btree node checksum
 */
#define BCACHE_BSET_CSUM		1
#define BCACHE_BSET_KEY_v1		2
#define BCACHE_BSET_JOURNAL_SEQ		3
#define BCACHE_BSET_VERSION		3

/*
 * Btree nodes
 *
 * On disk a btree node is a list/log of these; within each set the keys are
 * sorted
 */
struct bset {
	__le64			seq;

	/*
	 * Highest journal entry this bset contains keys for.
	 * If on recovery we don't see that journal entry, this bset is ignored:
	 * this allows us to preserve the order of all index updates after a
	 * crash, since the journal records a total order of all index updates
	 * and anything that didn't make it to the journal doesn't get used.
	 */
	__le64			journal_seq;

	__le32			flags;
	__le16			version;
	__le16			u64s; /* count of d[] in u64s */

	union {
		struct bkey_packed start[0];
		__u64		_data[0];
	};
} __attribute__((packed));

LE32_BITMASK(BSET_CSUM_TYPE,	struct bset, flags, 0, 4);

LE32_BITMASK(BSET_BIG_ENDIAN,	struct bset, flags, 4, 5);
LE32_BITMASK(BSET_SEPARATE_WHITEOUTS,
				struct bset, flags, 5, 6);

struct btree_node {
	struct bch_csum		csum;
	__le64			magic;

	/* this flags field is encrypted, unlike bset->flags: */
	__le64			flags;

	/* Closed interval: */
	struct bpos		min_key;
	struct bpos		max_key;
	struct bch_extent_ptr	ptr;
	struct bkey_format	format;

	union {
	struct bset		keys;
	struct {
		__u8		pad[22];
		__le16		u64s;
		__u64		_data[0];

	};
	};
} __attribute__((packed));

LE64_BITMASK(BTREE_NODE_ID,	struct btree_node, flags, 0, 4);
LE64_BITMASK(BTREE_NODE_LEVEL,	struct btree_node, flags, 4, 8);

struct btree_node_entry {
	struct bch_csum		csum;

	union {
	struct bset		keys;
	struct {
		__u8		pad[22];
		__le16		u64s;
		__u64		_data[0];

	};
	};
} __attribute__((packed));

#ifdef __cplusplus
}
#endif
#endif /* _LINUX_BCACHE_H */

/* vim: set foldnestmax=2: */