Contributors: 27
Author Tokens Token Proportion Commits Commit Proportion
Jeff Mahoney 1153 47.57% 2 1.82%
Chris Mason 691 28.51% 41 37.27%
Josef Whiter 169 6.97% 4 3.64%
Johannes Thumshirn 84 3.47% 4 3.64%
Zheng Yan 55 2.27% 7 6.36%
Qu Wenruo 47 1.94% 9 8.18%
Josef Bacik 44 1.82% 5 4.55%
Boris Burkov 42 1.73% 5 4.55%
David Sterba 31 1.28% 8 7.27%
Omar Sandoval 19 0.78% 2 1.82%
Chengguang Xu 16 0.66% 1 0.91%
Stefan Behrens 12 0.50% 4 3.64%
Nikolay Borisov 10 0.41% 1 0.91%
Alexander Block 10 0.41% 1 0.91%
Ilya Dryomov 9 0.37% 2 1.82%
Anand Jain 8 0.33% 2 1.82%
Nicolas Dichtel 6 0.25% 2 1.82%
Arne Jansen 5 0.21% 1 0.91%
Li Zefan 4 0.17% 1 0.91%
Fengguang Wu 2 0.08% 1 0.91%
Zach Brown 1 0.04% 1 0.91%
Greg Kroah-Hartman 1 0.04% 1 0.91%
Filipe David Borba Manana 1 0.04% 1 0.91%
Gustavo A. R. Silva 1 0.04% 1 0.91%
Geert Uytterhoeven 1 0.04% 1 0.91%
Phillip Potter 1 0.04% 1 0.91%
Wang Sheng-Hui 1 0.04% 1 0.91%
Total 2424 110 


/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
#ifndef _BTRFS_CTREE_H_
#define _BTRFS_CTREE_H_

#include <linux/btrfs.h>
#include <linux/types.h>
#ifdef __KERNEL__
#include <linux/stddef.h>
#else
#include <stddef.h>
#endif

/* ASCII for _BHRfS_M, no terminating nul */
#define BTRFS_MAGIC 0x4D5F53665248425FULL

#define BTRFS_MAX_LEVEL 8

/*
 * We can actually store much bigger names, but lets not confuse the rest of
 * linux.
 */
#define BTRFS_NAME_LEN 255

/*
 * Theoretical limit is larger, but we keep this down to a sane value. That
 * should limit greatly the possibility of collisions on inode ref items.
 */
#define BTRFS_LINK_MAX 65535U

/*
 * This header contains the structure definitions and constants used
 * by file system objects that can be retrieved using
 * the BTRFS_IOC_SEARCH_TREE ioctl.  That means basically anything that
 * is needed to describe a leaf node's key or item contents.
 */

/* holds pointers to all of the tree roots */
#define BTRFS_ROOT_TREE_OBJECTID 1ULL

/* stores information about which extents are in use, and reference counts */
#define BTRFS_EXTENT_TREE_OBJECTID 2ULL

/*
 * chunk tree stores translations from logical -> physical block numbering
 * the super block points to the chunk tree
 */
#define BTRFS_CHUNK_TREE_OBJECTID 3ULL

/*
 * stores information about which areas of a given device are in use.
 * one per device.  The tree of tree roots points to the device tree
 */
#define BTRFS_DEV_TREE_OBJECTID 4ULL

/* one per subvolume, storing files and directories */
#define BTRFS_FS_TREE_OBJECTID 5ULL

/* directory objectid inside the root tree */
#define BTRFS_ROOT_TREE_DIR_OBJECTID 6ULL

/* holds checksums of all the data extents */
#define BTRFS_CSUM_TREE_OBJECTID 7ULL

/* holds quota configuration and tracking */
#define BTRFS_QUOTA_TREE_OBJECTID 8ULL

/* for storing items that use the BTRFS_UUID_KEY* types */
#define BTRFS_UUID_TREE_OBJECTID 9ULL

/* tracks free space in block groups. */
#define BTRFS_FREE_SPACE_TREE_OBJECTID 10ULL

/* Holds the block group items for extent tree v2. */
#define BTRFS_BLOCK_GROUP_TREE_OBJECTID 11ULL

/* Tracks RAID stripes in block groups. */
#define BTRFS_RAID_STRIPE_TREE_OBJECTID 12ULL

/* device stats in the device tree */
#define BTRFS_DEV_STATS_OBJECTID 0ULL

/* for storing balance parameters in the root tree */
#define BTRFS_BALANCE_OBJECTID -4ULL

/* orphan objectid for tracking unlinked/truncated files */
#define BTRFS_ORPHAN_OBJECTID -5ULL

/* does write ahead logging to speed up fsyncs */
#define BTRFS_TREE_LOG_OBJECTID -6ULL
#define BTRFS_TREE_LOG_FIXUP_OBJECTID -7ULL

/* for space balancing */
#define BTRFS_TREE_RELOC_OBJECTID -8ULL
#define BTRFS_DATA_RELOC_TREE_OBJECTID -9ULL

/*
 * extent checksums all have this objectid
 * this allows them to share the logging tree
 * for fsyncs
 */
#define BTRFS_EXTENT_CSUM_OBJECTID -10ULL

/* For storing free space cache */
#define BTRFS_FREE_SPACE_OBJECTID -11ULL

/*
 * The inode number assigned to the special inode for storing
 * free ino cache
 */
#define BTRFS_FREE_INO_OBJECTID -12ULL

/* dummy objectid represents multiple objectids */
#define BTRFS_MULTIPLE_OBJECTIDS -255ULL

/*
 * All files have objectids in this range.
 */
#define BTRFS_FIRST_FREE_OBJECTID 256ULL
#define BTRFS_LAST_FREE_OBJECTID -256ULL
#define BTRFS_FIRST_CHUNK_TREE_OBJECTID 256ULL


/*
 * the device items go into the chunk tree.  The key is in the form
 * [ 1 BTRFS_DEV_ITEM_KEY device_id ]
 */
#define BTRFS_DEV_ITEMS_OBJECTID 1ULL

#define BTRFS_BTREE_INODE_OBJECTID 1

#define BTRFS_EMPTY_SUBVOL_DIR_OBJECTID 2

#define BTRFS_DEV_REPLACE_DEVID 0ULL

/*
 * inode items have the data typically returned from stat and store other
 * info about object characteristics.  There is one for every file and dir in
 * the FS
 */
#define BTRFS_INODE_ITEM_KEY		1
#define BTRFS_INODE_REF_KEY		12
#define BTRFS_INODE_EXTREF_KEY		13
#define BTRFS_XATTR_ITEM_KEY		24

/*
 * fs verity items are stored under two different key types on disk.
 * The descriptor items:
 * [ inode objectid, BTRFS_VERITY_DESC_ITEM_KEY, offset ]
 *
 * At offset 0, we store a btrfs_verity_descriptor_item which tracks the size
 * of the descriptor item and some extra data for encryption.
 * Starting at offset 1, these hold the generic fs verity descriptor.  The
 * latter are opaque to btrfs, we just read and write them as a blob for the
 * higher level verity code.  The most common descriptor size is 256 bytes.
 *
 * The merkle tree items:
 * [ inode objectid, BTRFS_VERITY_MERKLE_ITEM_KEY, offset ]
 *
 * These also start at offset 0, and correspond to the merkle tree bytes.  When
 * fsverity asks for page 0 of the merkle tree, we pull up one page starting at
 * offset 0 for this key type.  These are also opaque to btrfs, we're blindly
 * storing whatever fsverity sends down.
 */
#define BTRFS_VERITY_DESC_ITEM_KEY	36
#define BTRFS_VERITY_MERKLE_ITEM_KEY	37

#define BTRFS_ORPHAN_ITEM_KEY		48
/* reserve 2-15 close to the inode for later flexibility */

/*
 * dir items are the name -> inode pointers in a directory.  There is one
 * for every name in a directory.  BTRFS_DIR_LOG_ITEM_KEY is no longer used
 * but it's still defined here for documentation purposes and to help avoid
 * having its numerical value reused in the future.
 */
#define BTRFS_DIR_LOG_ITEM_KEY  60
#define BTRFS_DIR_LOG_INDEX_KEY 72
#define BTRFS_DIR_ITEM_KEY	84
#define BTRFS_DIR_INDEX_KEY	96
/*
 * extent data is for file data
 */
#define BTRFS_EXTENT_DATA_KEY	108

/*
 * extent csums are stored in a separate tree and hold csums for
 * an entire extent on disk.
 */
#define BTRFS_EXTENT_CSUM_KEY	128

/*
 * root items point to tree roots.  They are typically in the root
 * tree used by the super block to find all the other trees
 */
#define BTRFS_ROOT_ITEM_KEY	132

/*
 * root backrefs tie subvols and snapshots to the directory entries that
 * reference them
 */
#define BTRFS_ROOT_BACKREF_KEY	144

/*
 * root refs make a fast index for listing all of the snapshots and
 * subvolumes referenced by a given root.  They point directly to the
 * directory item in the root that references the subvol
 */
#define BTRFS_ROOT_REF_KEY	156

/*
 * extent items are in the extent map tree.  These record which blocks
 * are used, and how many references there are to each block
 */
#define BTRFS_EXTENT_ITEM_KEY	168

/*
 * The same as the BTRFS_EXTENT_ITEM_KEY, except it's metadata we already know
 * the length, so we save the level in key->offset instead of the length.
 */
#define BTRFS_METADATA_ITEM_KEY	169

/*
 * Special inline ref key which stores the id of the subvolume which originally
 * created the extent. This subvolume owns the extent permanently from the
 * perspective of simple quotas. Needed to know which subvolume to free quota
 * usage from when the extent is deleted.
 *
 * Stored as an inline ref rather to avoid wasting space on a separate item on
 * top of the existing extent item. However, unlike the other inline refs,
 * there is one one owner ref per extent rather than one per extent.
 *
 * Because of this, it goes at the front of the list of inline refs, and thus
 * must have a lower type value than any other inline ref type (to satisfy the
 * disk format rule that inline refs have non-decreasing type).
 */
#define BTRFS_EXTENT_OWNER_REF_KEY	172

#define BTRFS_TREE_BLOCK_REF_KEY	176

#define BTRFS_EXTENT_DATA_REF_KEY	178

/*
 * Obsolete key. Defintion removed in 6.6, value may be reused in the future.
 *
 * #define BTRFS_EXTENT_REF_V0_KEY	180
 */

#define BTRFS_SHARED_BLOCK_REF_KEY	182

#define BTRFS_SHARED_DATA_REF_KEY	184

/*
 * block groups give us hints into the extent allocation trees.  Which
 * blocks are free etc etc
 */
#define BTRFS_BLOCK_GROUP_ITEM_KEY 192

/*
 * Every block group is represented in the free space tree by a free space info
 * item, which stores some accounting information. It is keyed on
 * (block_group_start, FREE_SPACE_INFO, block_group_length).
 */
#define BTRFS_FREE_SPACE_INFO_KEY 198

/*
 * A free space extent tracks an extent of space that is free in a block group.
 * It is keyed on (start, FREE_SPACE_EXTENT, length).
 */
#define BTRFS_FREE_SPACE_EXTENT_KEY 199

/*
 * When a block group becomes very fragmented, we convert it to use bitmaps
 * instead of extents. A free space bitmap is keyed on
 * (start, FREE_SPACE_BITMAP, length); the corresponding item is a bitmap with
 * (length / sectorsize) bits.
 */
#define BTRFS_FREE_SPACE_BITMAP_KEY 200

#define BTRFS_DEV_EXTENT_KEY	204
#define BTRFS_DEV_ITEM_KEY	216
#define BTRFS_CHUNK_ITEM_KEY	228

#define BTRFS_RAID_STRIPE_KEY	230

/*
 * Records the overall state of the qgroups.
 * There's only one instance of this key present,
 * (0, BTRFS_QGROUP_STATUS_KEY, 0)
 */
#define BTRFS_QGROUP_STATUS_KEY         240
/*
 * Records the currently used space of the qgroup.
 * One key per qgroup, (0, BTRFS_QGROUP_INFO_KEY, qgroupid).
 */
#define BTRFS_QGROUP_INFO_KEY           242
/*
 * Contains the user configured limits for the qgroup.
 * One key per qgroup, (0, BTRFS_QGROUP_LIMIT_KEY, qgroupid).
 */
#define BTRFS_QGROUP_LIMIT_KEY          244
/*
 * Records the child-parent relationship of qgroups. For
 * each relation, 2 keys are present:
 * (childid, BTRFS_QGROUP_RELATION_KEY, parentid)
 * (parentid, BTRFS_QGROUP_RELATION_KEY, childid)
 */
#define BTRFS_QGROUP_RELATION_KEY       246

/*
 * Obsolete name, see BTRFS_TEMPORARY_ITEM_KEY.
 */
#define BTRFS_BALANCE_ITEM_KEY	248

/*
 * The key type for tree items that are stored persistently, but do not need to
 * exist for extended period of time. The items can exist in any tree.
 *
 * [subtype, BTRFS_TEMPORARY_ITEM_KEY, data]
 *
 * Existing items:
 *
 * - balance status item
 *   (BTRFS_BALANCE_OBJECTID, BTRFS_TEMPORARY_ITEM_KEY, 0)
 */
#define BTRFS_TEMPORARY_ITEM_KEY	248

/*
 * Obsolete name, see BTRFS_PERSISTENT_ITEM_KEY
 */
#define BTRFS_DEV_STATS_KEY		249

/*
 * The key type for tree items that are stored persistently and usually exist
 * for a long period, eg. filesystem lifetime. The item kinds can be status
 * information, stats or preference values. The item can exist in any tree.
 *
 * [subtype, BTRFS_PERSISTENT_ITEM_KEY, data]
 *
 * Existing items:
 *
 * - device statistics, store IO stats in the device tree, one key for all
 *   stats
 *   (BTRFS_DEV_STATS_OBJECTID, BTRFS_DEV_STATS_KEY, 0)
 */
#define BTRFS_PERSISTENT_ITEM_KEY	249

/*
 * Persistently stores the device replace state in the device tree.
 * The key is built like this: (0, BTRFS_DEV_REPLACE_KEY, 0).
 */
#define BTRFS_DEV_REPLACE_KEY	250

/*
 * Stores items that allow to quickly map UUIDs to something else.
 * These items are part of the filesystem UUID tree.
 * The key is built like this:
 * (UUID_upper_64_bits, BTRFS_UUID_KEY*, UUID_lower_64_bits).
 */
#if BTRFS_UUID_SIZE != 16
#error "UUID items require BTRFS_UUID_SIZE == 16!"
#endif
#define BTRFS_UUID_KEY_SUBVOL	251	/* for UUIDs assigned to subvols */
#define BTRFS_UUID_KEY_RECEIVED_SUBVOL	252	/* for UUIDs assigned to
						 * received subvols */

/*
 * string items are for debugging.  They just store a short string of
 * data in the FS
 */
#define BTRFS_STRING_ITEM_KEY	253

/* Maximum metadata block size (nodesize) */
#define BTRFS_MAX_METADATA_BLOCKSIZE			65536

/* 32 bytes in various csum fields */
#define BTRFS_CSUM_SIZE 32

/* csum types */
enum btrfs_csum_type {
	BTRFS_CSUM_TYPE_CRC32	= 0,
	BTRFS_CSUM_TYPE_XXHASH	= 1,
	BTRFS_CSUM_TYPE_SHA256	= 2,
	BTRFS_CSUM_TYPE_BLAKE2	= 3,
};

/*
 * flags definitions for directory entry item type
 *
 * Used by:
 * struct btrfs_dir_item.type
 *
 * Values 0..7 must match common file type values in fs_types.h.
 */
#define BTRFS_FT_UNKNOWN	0
#define BTRFS_FT_REG_FILE	1
#define BTRFS_FT_DIR		2
#define BTRFS_FT_CHRDEV		3
#define BTRFS_FT_BLKDEV		4
#define BTRFS_FT_FIFO		5
#define BTRFS_FT_SOCK		6
#define BTRFS_FT_SYMLINK	7
#define BTRFS_FT_XATTR		8
#define BTRFS_FT_MAX		9
/* Directory contains encrypted data */
#define BTRFS_FT_ENCRYPTED	0x80

static inline __u8 btrfs_dir_flags_to_ftype(__u8 flags)
{
	return flags & ~BTRFS_FT_ENCRYPTED;
}

/*
 * Inode flags
 */
#define BTRFS_INODE_NODATASUM		(1U << 0)
#define BTRFS_INODE_NODATACOW		(1U << 1)
#define BTRFS_INODE_READONLY		(1U << 2)
#define BTRFS_INODE_NOCOMPRESS		(1U << 3)
#define BTRFS_INODE_PREALLOC		(1U << 4)
#define BTRFS_INODE_SYNC		(1U << 5)
#define BTRFS_INODE_IMMUTABLE		(1U << 6)
#define BTRFS_INODE_APPEND		(1U << 7)
#define BTRFS_INODE_NODUMP		(1U << 8)
#define BTRFS_INODE_NOATIME		(1U << 9)
#define BTRFS_INODE_DIRSYNC		(1U << 10)
#define BTRFS_INODE_COMPRESS		(1U << 11)

#define BTRFS_INODE_ROOT_ITEM_INIT	(1U << 31)

#define BTRFS_INODE_FLAG_MASK						\
	(BTRFS_INODE_NODATASUM |					\
	 BTRFS_INODE_NODATACOW |					\
	 BTRFS_INODE_READONLY |						\
	 BTRFS_INODE_NOCOMPRESS |					\
	 BTRFS_INODE_PREALLOC |						\
	 BTRFS_INODE_SYNC |						\
	 BTRFS_INODE_IMMUTABLE |					\
	 BTRFS_INODE_APPEND |						\
	 BTRFS_INODE_NODUMP |						\
	 BTRFS_INODE_NOATIME |						\
	 BTRFS_INODE_DIRSYNC |						\
	 BTRFS_INODE_COMPRESS |						\
	 BTRFS_INODE_ROOT_ITEM_INIT)

#define BTRFS_INODE_RO_VERITY		(1U << 0)

#define BTRFS_INODE_RO_FLAG_MASK	(BTRFS_INODE_RO_VERITY)

/*
 * The key defines the order in the tree, and so it also defines (optimal)
 * block layout.
 *
 * objectid corresponds to the inode number.
 *
 * type tells us things about the object, and is a kind of stream selector.
 * so for a given inode, keys with type of 1 might refer to the inode data,
 * type of 2 may point to file data in the btree and type == 3 may point to
 * extents.
 *
 * offset is the starting byte offset for this key in the stream.
 *
 * btrfs_disk_key is in disk byte order.  struct btrfs_key is always
 * in cpu native order.  Otherwise they are identical and their sizes
 * should be the same (ie both packed)
 */
struct btrfs_disk_key {
	__le64 objectid;
	__u8 type;
	__le64 offset;
} __attribute__ ((__packed__));

struct btrfs_key {
	__u64 objectid;
	__u8 type;
	__u64 offset;
} __attribute__ ((__packed__));

/*
 * Every tree block (leaf or node) starts with this header.
 */
struct btrfs_header {
	/* These first four must match the super block */
	__u8 csum[BTRFS_CSUM_SIZE];
	/* FS specific uuid */
	__u8 fsid[BTRFS_FSID_SIZE];
	/* Which block this node is supposed to live in */
	__le64 bytenr;
	__le64 flags;

	/* Allowed to be different from the super from here on down */
	__u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
	__le64 generation;
	__le64 owner;
	__le32 nritems;
	__u8 level;
} __attribute__ ((__packed__));

/*
 * This is a very generous portion of the super block, giving us room to
 * translate 14 chunks with 3 stripes each.
 */
#define BTRFS_SYSTEM_CHUNK_ARRAY_SIZE 2048

/*
 * Just in case we somehow lose the roots and are not able to mount, we store
 * an array of the roots from previous transactions in the super.
 */
#define BTRFS_NUM_BACKUP_ROOTS 4
struct btrfs_root_backup {
	__le64 tree_root;
	__le64 tree_root_gen;

	__le64 chunk_root;
	__le64 chunk_root_gen;

	__le64 extent_root;
	__le64 extent_root_gen;

	__le64 fs_root;
	__le64 fs_root_gen;

	__le64 dev_root;
	__le64 dev_root_gen;

	__le64 csum_root;
	__le64 csum_root_gen;

	__le64 total_bytes;
	__le64 bytes_used;
	__le64 num_devices;
	/* future */
	__le64 unused_64[4];

	__u8 tree_root_level;
	__u8 chunk_root_level;
	__u8 extent_root_level;
	__u8 fs_root_level;
	__u8 dev_root_level;
	__u8 csum_root_level;
	/* future and to align */
	__u8 unused_8[10];
} __attribute__ ((__packed__));

/*
 * A leaf is full of items. offset and size tell us where to find the item in
 * the leaf (relative to the start of the data area)
 */
struct btrfs_item {
	struct btrfs_disk_key key;
	__le32 offset;
	__le32 size;
} __attribute__ ((__packed__));

/*
 * Leaves have an item area and a data area:
 * [item0, item1....itemN] [free space] [dataN...data1, data0]
 *
 * The data is separate from the items to get the keys closer together during
 * searches.
 */
struct btrfs_leaf {
	struct btrfs_header header;
	struct btrfs_item items[];
} __attribute__ ((__packed__));

/*
 * All non-leaf blocks are nodes, they hold only keys and pointers to other
 * blocks.
 */
struct btrfs_key_ptr {
	struct btrfs_disk_key key;
	__le64 blockptr;
	__le64 generation;
} __attribute__ ((__packed__));

struct btrfs_node {
	struct btrfs_header header;
	struct btrfs_key_ptr ptrs[];
} __attribute__ ((__packed__));

struct btrfs_dev_item {
	/* the internal btrfs device id */
	__le64 devid;

	/* size of the device */
	__le64 total_bytes;

	/* bytes used */
	__le64 bytes_used;

	/* optimal io alignment for this device */
	__le32 io_align;

	/* optimal io width for this device */
	__le32 io_width;

	/* minimal io size for this device */
	__le32 sector_size;

	/* type and info about this device */
	__le64 type;

	/* expected generation for this device */
	__le64 generation;

	/*
	 * starting byte of this partition on the device,
	 * to allow for stripe alignment in the future
	 */
	__le64 start_offset;

	/* grouping information for allocation decisions */
	__le32 dev_group;

	/* seek speed 0-100 where 100 is fastest */
	__u8 seek_speed;

	/* bandwidth 0-100 where 100 is fastest */
	__u8 bandwidth;

	/* btrfs generated uuid for this device */
	__u8 uuid[BTRFS_UUID_SIZE];

	/* uuid of FS who owns this device */
	__u8 fsid[BTRFS_UUID_SIZE];
} __attribute__ ((__packed__));

struct btrfs_stripe {
	__le64 devid;
	__le64 offset;
	__u8 dev_uuid[BTRFS_UUID_SIZE];
} __attribute__ ((__packed__));

struct btrfs_chunk {
	/* size of this chunk in bytes */
	__le64 length;

	/* objectid of the root referencing this chunk */
	__le64 owner;

	__le64 stripe_len;
	__le64 type;

	/* optimal io alignment for this chunk */
	__le32 io_align;

	/* optimal io width for this chunk */
	__le32 io_width;

	/* minimal io size for this chunk */
	__le32 sector_size;

	/* 2^16 stripes is quite a lot, a second limit is the size of a single
	 * item in the btree
	 */
	__le16 num_stripes;

	/* sub stripes only matter for raid10 */
	__le16 sub_stripes;
	struct btrfs_stripe stripe;
	/* additional stripes go here */
} __attribute__ ((__packed__));

/*
 * The super block basically lists the main trees of the FS.
 */
struct btrfs_super_block {
	/* The first 4 fields must match struct btrfs_header */
	__u8 csum[BTRFS_CSUM_SIZE];
	/* FS specific UUID, visible to user */
	__u8 fsid[BTRFS_FSID_SIZE];
	/* This block number */
	__le64 bytenr;
	__le64 flags;

	/* Allowed to be different from the btrfs_header from here own down */
	__le64 magic;
	__le64 generation;
	__le64 root;
	__le64 chunk_root;
	__le64 log_root;

	/*
	 * This member has never been utilized since the very beginning, thus
	 * it's always 0 regardless of kernel version.  We always use
	 * generation + 1 to read log tree root.  So here we mark it deprecated.
	 */
	__le64 __unused_log_root_transid;
	__le64 total_bytes;
	__le64 bytes_used;
	__le64 root_dir_objectid;
	__le64 num_devices;
	__le32 sectorsize;
	__le32 nodesize;
	__le32 __unused_leafsize;
	__le32 stripesize;
	__le32 sys_chunk_array_size;
	__le64 chunk_root_generation;
	__le64 compat_flags;
	__le64 compat_ro_flags;
	__le64 incompat_flags;
	__le16 csum_type;
	__u8 root_level;
	__u8 chunk_root_level;
	__u8 log_root_level;
	struct btrfs_dev_item dev_item;

	char label[BTRFS_LABEL_SIZE];

	__le64 cache_generation;
	__le64 uuid_tree_generation;

	/* The UUID written into btree blocks */
	__u8 metadata_uuid[BTRFS_FSID_SIZE];

	__u64 nr_global_roots;

	/* Future expansion */
	__le64 reserved[27];
	__u8 sys_chunk_array[BTRFS_SYSTEM_CHUNK_ARRAY_SIZE];
	struct btrfs_root_backup super_roots[BTRFS_NUM_BACKUP_ROOTS];

	/* Padded to 4096 bytes */
	__u8 padding[565];
} __attribute__ ((__packed__));

#define BTRFS_FREE_SPACE_EXTENT	1
#define BTRFS_FREE_SPACE_BITMAP	2

struct btrfs_free_space_entry {
	__le64 offset;
	__le64 bytes;
	__u8 type;
} __attribute__ ((__packed__));

struct btrfs_free_space_header {
	struct btrfs_disk_key location;
	__le64 generation;
	__le64 num_entries;
	__le64 num_bitmaps;
} __attribute__ ((__packed__));

struct btrfs_raid_stride {
	/* The id of device this raid extent lives on. */
	__le64 devid;
	/* The physical location on disk. */
	__le64 physical;
} __attribute__ ((__packed__));

/* The stripe_extent::encoding, 1:1 mapping of enum btrfs_raid_types. */
#define BTRFS_STRIPE_RAID0	1
#define BTRFS_STRIPE_RAID1	2
#define BTRFS_STRIPE_DUP	3
#define BTRFS_STRIPE_RAID10	4
#define BTRFS_STRIPE_RAID5	5
#define BTRFS_STRIPE_RAID6	6
#define BTRFS_STRIPE_RAID1C3	7
#define BTRFS_STRIPE_RAID1C4	8

struct btrfs_stripe_extent {
	__u8 encoding;
	__u8 reserved[7];
	/* An array of raid strides this stripe is composed of. */
	struct btrfs_raid_stride strides[];
} __attribute__ ((__packed__));

#define BTRFS_HEADER_FLAG_WRITTEN	(1ULL << 0)
#define BTRFS_HEADER_FLAG_RELOC		(1ULL << 1)

/* Super block flags */
/* Errors detected */
#define BTRFS_SUPER_FLAG_ERROR		(1ULL << 2)

#define BTRFS_SUPER_FLAG_SEEDING	(1ULL << 32)
#define BTRFS_SUPER_FLAG_METADUMP	(1ULL << 33)
#define BTRFS_SUPER_FLAG_METADUMP_V2	(1ULL << 34)
#define BTRFS_SUPER_FLAG_CHANGING_FSID	(1ULL << 35)
#define BTRFS_SUPER_FLAG_CHANGING_FSID_V2 (1ULL << 36)


/*
 * items in the extent btree are used to record the objectid of the
 * owner of the block and the number of references
 */

struct btrfs_extent_item {
	__le64 refs;
	__le64 generation;
	__le64 flags;
} __attribute__ ((__packed__));

struct btrfs_extent_item_v0 {
	__le32 refs;
} __attribute__ ((__packed__));


#define BTRFS_EXTENT_FLAG_DATA		(1ULL << 0)
#define BTRFS_EXTENT_FLAG_TREE_BLOCK	(1ULL << 1)

/* following flags only apply to tree blocks */

/* use full backrefs for extent pointers in the block */
#define BTRFS_BLOCK_FLAG_FULL_BACKREF	(1ULL << 8)

#define BTRFS_BACKREF_REV_MAX		256
#define BTRFS_BACKREF_REV_SHIFT		56
#define BTRFS_BACKREF_REV_MASK		(((u64)BTRFS_BACKREF_REV_MAX - 1) << \
					 BTRFS_BACKREF_REV_SHIFT)

#define BTRFS_OLD_BACKREF_REV		0
#define BTRFS_MIXED_BACKREF_REV		1

/*
 * this flag is only used internally by scrub and may be changed at any time
 * it is only declared here to avoid collisions
 */
#define BTRFS_EXTENT_FLAG_SUPER		(1ULL << 48)

struct btrfs_tree_block_info {
	struct btrfs_disk_key key;
	__u8 level;
} __attribute__ ((__packed__));

struct btrfs_extent_data_ref {
	__le64 root;
	__le64 objectid;
	__le64 offset;
	__le32 count;
} __attribute__ ((__packed__));

struct btrfs_shared_data_ref {
	__le32 count;
} __attribute__ ((__packed__));

struct btrfs_extent_owner_ref {
	__le64 root_id;
} __attribute__ ((__packed__));

struct btrfs_extent_inline_ref {
	__u8 type;
	__le64 offset;
} __attribute__ ((__packed__));

/* dev extents record free space on individual devices.  The owner
 * field points back to the chunk allocation mapping tree that allocated
 * the extent.  The chunk tree uuid field is a way to double check the owner
 */
struct btrfs_dev_extent {
	__le64 chunk_tree;
	__le64 chunk_objectid;
	__le64 chunk_offset;
	__le64 length;
	__u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
} __attribute__ ((__packed__));

struct btrfs_inode_ref {
	__le64 index;
	__le16 name_len;
	/* name goes here */
} __attribute__ ((__packed__));

struct btrfs_inode_extref {
	__le64 parent_objectid;
	__le64 index;
	__le16 name_len;
	__u8   name[];
	/* name goes here */
} __attribute__ ((__packed__));

struct btrfs_timespec {
	__le64 sec;
	__le32 nsec;
} __attribute__ ((__packed__));

struct btrfs_inode_item {
	/* nfs style generation number */
	__le64 generation;
	/* transid that last touched this inode */
	__le64 transid;
	__le64 size;
	__le64 nbytes;
	__le64 block_group;
	__le32 nlink;
	__le32 uid;
	__le32 gid;
	__le32 mode;
	__le64 rdev;
	__le64 flags;

	/* modification sequence number for NFS */
	__le64 sequence;

	/*
	 * a little future expansion, for more than this we can
	 * just grow the inode item and version it
	 */
	__le64 reserved[4];
	struct btrfs_timespec atime;
	struct btrfs_timespec ctime;
	struct btrfs_timespec mtime;
	struct btrfs_timespec otime;
} __attribute__ ((__packed__));

struct btrfs_dir_log_item {
	__le64 end;
} __attribute__ ((__packed__));

struct btrfs_dir_item {
	struct btrfs_disk_key location;
	__le64 transid;
	__le16 data_len;
	__le16 name_len;
	__u8 type;
} __attribute__ ((__packed__));

#define BTRFS_ROOT_SUBVOL_RDONLY	(1ULL << 0)

/*
 * Internal in-memory flag that a subvolume has been marked for deletion but
 * still visible as a directory
 */
#define BTRFS_ROOT_SUBVOL_DEAD		(1ULL << 48)

struct btrfs_root_item {
	struct btrfs_inode_item inode;
	__le64 generation;
	__le64 root_dirid;
	__le64 bytenr;
	__le64 byte_limit;
	__le64 bytes_used;
	__le64 last_snapshot;
	__le64 flags;
	__le32 refs;
	struct btrfs_disk_key drop_progress;
	__u8 drop_level;
	__u8 level;

	/*
	 * The following fields appear after subvol_uuids+subvol_times
	 * were introduced.
	 */

	/*
	 * This generation number is used to test if the new fields are valid
	 * and up to date while reading the root item. Every time the root item
	 * is written out, the "generation" field is copied into this field. If
	 * anyone ever mounted the fs with an older kernel, we will have
	 * mismatching generation values here and thus must invalidate the
	 * new fields. See btrfs_update_root and btrfs_find_last_root for
	 * details.
	 * the offset of generation_v2 is also used as the start for the memset
	 * when invalidating the fields.
	 */
	__le64 generation_v2;
	__u8 uuid[BTRFS_UUID_SIZE];
	__u8 parent_uuid[BTRFS_UUID_SIZE];
	__u8 received_uuid[BTRFS_UUID_SIZE];
	__le64 ctransid; /* updated when an inode changes */
	__le64 otransid; /* trans when created */
	__le64 stransid; /* trans when sent. non-zero for received subvol */
	__le64 rtransid; /* trans when received. non-zero for received subvol */
	struct btrfs_timespec ctime;
	struct btrfs_timespec otime;
	struct btrfs_timespec stime;
	struct btrfs_timespec rtime;
	__le64 reserved[8]; /* for future */
} __attribute__ ((__packed__));

/*
 * Btrfs root item used to be smaller than current size.  The old format ends
 * at where member generation_v2 is.
 */
static inline __u32 btrfs_legacy_root_item_size(void)
{
	return offsetof(struct btrfs_root_item, generation_v2);
}

/*
 * this is used for both forward and backward root refs
 */
struct btrfs_root_ref {
	__le64 dirid;
	__le64 sequence;
	__le16 name_len;
} __attribute__ ((__packed__));

struct btrfs_disk_balance_args {
	/*
	 * profiles to operate on, single is denoted by
	 * BTRFS_AVAIL_ALLOC_BIT_SINGLE
	 */
	__le64 profiles;

	/*
	 * usage filter
	 * BTRFS_BALANCE_ARGS_USAGE with a single value means '0..N'
	 * BTRFS_BALANCE_ARGS_USAGE_RANGE - range syntax, min..max
	 */
	union {
		__le64 usage;
		struct {
			__le32 usage_min;
			__le32 usage_max;
		};
	};

	/* devid filter */
	__le64 devid;

	/* devid subset filter [pstart..pend) */
	__le64 pstart;
	__le64 pend;

	/* btrfs virtual address space subset filter [vstart..vend) */
	__le64 vstart;
	__le64 vend;

	/*
	 * profile to convert to, single is denoted by
	 * BTRFS_AVAIL_ALLOC_BIT_SINGLE
	 */
	__le64 target;

	/* BTRFS_BALANCE_ARGS_* */
	__le64 flags;

	/*
	 * BTRFS_BALANCE_ARGS_LIMIT with value 'limit'
	 * BTRFS_BALANCE_ARGS_LIMIT_RANGE - the extend version can use minimum
	 * and maximum
	 */
	union {
		__le64 limit;
		struct {
			__le32 limit_min;
			__le32 limit_max;
		};
	};

	/*
	 * Process chunks that cross stripes_min..stripes_max devices,
	 * BTRFS_BALANCE_ARGS_STRIPES_RANGE
	 */
	__le32 stripes_min;
	__le32 stripes_max;

	__le64 unused[6];
} __attribute__ ((__packed__));

/*
 * store balance parameters to disk so that balance can be properly
 * resumed after crash or unmount
 */
struct btrfs_balance_item {
	/* BTRFS_BALANCE_* */
	__le64 flags;

	struct btrfs_disk_balance_args data;
	struct btrfs_disk_balance_args meta;
	struct btrfs_disk_balance_args sys;

	__le64 unused[4];
} __attribute__ ((__packed__));

enum {
	BTRFS_FILE_EXTENT_INLINE   = 0,
	BTRFS_FILE_EXTENT_REG      = 1,
	BTRFS_FILE_EXTENT_PREALLOC = 2,
	BTRFS_NR_FILE_EXTENT_TYPES = 3,
};

struct btrfs_file_extent_item {
	/*
	 * transaction id that created this extent
	 */
	__le64 generation;
	/*
	 * max number of bytes to hold this extent in ram
	 * when we split a compressed extent we can't know how big
	 * each of the resulting pieces will be.  So, this is
	 * an upper limit on the size of the extent in ram instead of
	 * an exact limit.
	 */
	__le64 ram_bytes;

	/*
	 * 32 bits for the various ways we might encode the data,
	 * including compression and encryption.  If any of these
	 * are set to something a given disk format doesn't understand
	 * it is treated like an incompat flag for reading and writing,
	 * but not for stat.
	 */
	__u8 compression;
	__u8 encryption;
	__le16 other_encoding; /* spare for later use */

	/* are we inline data or a real extent? */
	__u8 type;

	/*
	 * disk space consumed by the extent, checksum blocks are included
	 * in these numbers
	 *
	 * At this offset in the structure, the inline extent data start.
	 */
	__le64 disk_bytenr;
	__le64 disk_num_bytes;
	/*
	 * the logical offset in file blocks (no csums)
	 * this extent record is for.  This allows a file extent to point
	 * into the middle of an existing extent on disk, sharing it
	 * between two snapshots (useful if some bytes in the middle of the
	 * extent have changed
	 */
	__le64 offset;
	/*
	 * the logical number of file blocks (no csums included).  This
	 * always reflects the size uncompressed and without encoding.
	 */
	__le64 num_bytes;

} __attribute__ ((__packed__));

struct btrfs_csum_item {
	__u8 csum;
} __attribute__ ((__packed__));

struct btrfs_dev_stats_item {
	/*
	 * grow this item struct at the end for future enhancements and keep
	 * the existing values unchanged
	 */
	__le64 values[BTRFS_DEV_STAT_VALUES_MAX];
} __attribute__ ((__packed__));

#define BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS	0
#define BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_AVOID	1

struct btrfs_dev_replace_item {
	/*
	 * grow this item struct at the end for future enhancements and keep
	 * the existing values unchanged
	 */
	__le64 src_devid;
	__le64 cursor_left;
	__le64 cursor_right;
	__le64 cont_reading_from_srcdev_mode;

	__le64 replace_state;
	__le64 time_started;
	__le64 time_stopped;
	__le64 num_write_errors;
	__le64 num_uncorrectable_read_errors;
} __attribute__ ((__packed__));

/* different types of block groups (and chunks) */
#define BTRFS_BLOCK_GROUP_DATA		(1ULL << 0)
#define BTRFS_BLOCK_GROUP_SYSTEM	(1ULL << 1)
#define BTRFS_BLOCK_GROUP_METADATA	(1ULL << 2)
#define BTRFS_BLOCK_GROUP_RAID0		(1ULL << 3)
#define BTRFS_BLOCK_GROUP_RAID1		(1ULL << 4)
#define BTRFS_BLOCK_GROUP_DUP		(1ULL << 5)
#define BTRFS_BLOCK_GROUP_RAID10	(1ULL << 6)
#define BTRFS_BLOCK_GROUP_RAID5         (1ULL << 7)
#define BTRFS_BLOCK_GROUP_RAID6         (1ULL << 8)
#define BTRFS_BLOCK_GROUP_RAID1C3       (1ULL << 9)
#define BTRFS_BLOCK_GROUP_RAID1C4       (1ULL << 10)
#define BTRFS_BLOCK_GROUP_RESERVED	(BTRFS_AVAIL_ALLOC_BIT_SINGLE | \
					 BTRFS_SPACE_INFO_GLOBAL_RSV)

#define BTRFS_BLOCK_GROUP_TYPE_MASK	(BTRFS_BLOCK_GROUP_DATA |    \
					 BTRFS_BLOCK_GROUP_SYSTEM |  \
					 BTRFS_BLOCK_GROUP_METADATA)

#define BTRFS_BLOCK_GROUP_PROFILE_MASK	(BTRFS_BLOCK_GROUP_RAID0 |   \
					 BTRFS_BLOCK_GROUP_RAID1 |   \
					 BTRFS_BLOCK_GROUP_RAID1C3 | \
					 BTRFS_BLOCK_GROUP_RAID1C4 | \
					 BTRFS_BLOCK_GROUP_RAID5 |   \
					 BTRFS_BLOCK_GROUP_RAID6 |   \
					 BTRFS_BLOCK_GROUP_DUP |     \
					 BTRFS_BLOCK_GROUP_RAID10)
#define BTRFS_BLOCK_GROUP_RAID56_MASK	(BTRFS_BLOCK_GROUP_RAID5 |   \
					 BTRFS_BLOCK_GROUP_RAID6)

#define BTRFS_BLOCK_GROUP_RAID1_MASK	(BTRFS_BLOCK_GROUP_RAID1 |   \
					 BTRFS_BLOCK_GROUP_RAID1C3 | \
					 BTRFS_BLOCK_GROUP_RAID1C4)

/*
 * We need a bit for restriper to be able to tell when chunks of type
 * SINGLE are available.  This "extended" profile format is used in
 * fs_info->avail_*_alloc_bits (in-memory) and balance item fields
 * (on-disk).  The corresponding on-disk bit in chunk.type is reserved
 * to avoid remappings between two formats in future.
 */
#define BTRFS_AVAIL_ALLOC_BIT_SINGLE	(1ULL << 48)

/*
 * A fake block group type that is used to communicate global block reserve
 * size to userspace via the SPACE_INFO ioctl.
 */
#define BTRFS_SPACE_INFO_GLOBAL_RSV	(1ULL << 49)

#define BTRFS_EXTENDED_PROFILE_MASK	(BTRFS_BLOCK_GROUP_PROFILE_MASK | \
					 BTRFS_AVAIL_ALLOC_BIT_SINGLE)

static inline __u64 chunk_to_extended(__u64 flags)
{
	if ((flags & BTRFS_BLOCK_GROUP_PROFILE_MASK) == 0)
		flags |= BTRFS_AVAIL_ALLOC_BIT_SINGLE;

	return flags;
}
static inline __u64 extended_to_chunk(__u64 flags)
{
	return flags & ~BTRFS_AVAIL_ALLOC_BIT_SINGLE;
}

struct btrfs_block_group_item {
	__le64 used;
	__le64 chunk_objectid;
	__le64 flags;
} __attribute__ ((__packed__));

struct btrfs_free_space_info {
	__le32 extent_count;
	__le32 flags;
} __attribute__ ((__packed__));

#define BTRFS_FREE_SPACE_USING_BITMAPS (1ULL << 0)

#define BTRFS_QGROUP_LEVEL_SHIFT		48
static inline __u16 btrfs_qgroup_level(__u64 qgroupid)
{
	return (__u16)(qgroupid >> BTRFS_QGROUP_LEVEL_SHIFT);
}

/*
 * is subvolume quota turned on?
 */
#define BTRFS_QGROUP_STATUS_FLAG_ON		(1ULL << 0)
/*
 * RESCAN is set during the initialization phase
 */
#define BTRFS_QGROUP_STATUS_FLAG_RESCAN		(1ULL << 1)
/*
 * Some qgroup entries are known to be out of date,
 * either because the configuration has changed in a way that
 * makes a rescan necessary, or because the fs has been mounted
 * with a non-qgroup-aware version.
 * Turning qouta off and on again makes it inconsistent, too.
 */
#define BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT	(1ULL << 2)

/*
 * Whether or not this filesystem is using simple quotas.  Not exactly the
 * incompat bit, because we support using simple quotas, disabling it, then
 * going back to full qgroup quotas.
 */
#define BTRFS_QGROUP_STATUS_FLAG_SIMPLE_MODE	(1ULL << 3)

#define BTRFS_QGROUP_STATUS_FLAGS_MASK	(BTRFS_QGROUP_STATUS_FLAG_ON |		\
					 BTRFS_QGROUP_STATUS_FLAG_RESCAN |	\
					 BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT | \
					 BTRFS_QGROUP_STATUS_FLAG_SIMPLE_MODE)

#define BTRFS_QGROUP_STATUS_VERSION        1

struct btrfs_qgroup_status_item {
	__le64 version;
	/*
	 * the generation is updated during every commit. As older
	 * versions of btrfs are not aware of qgroups, it will be
	 * possible to detect inconsistencies by checking the
	 * generation on mount time
	 */
	__le64 generation;

	/* flag definitions see above */
	__le64 flags;

	/*
	 * only used during scanning to record the progress
	 * of the scan. It contains a logical address
	 */
	__le64 rescan;

	/*
	 * The generation when quotas were last enabled. Used by simple quotas to
	 * avoid decrementing when freeing an extent that was written before
	 * enable.
	 *
	 * Set only if flags contain BTRFS_QGROUP_STATUS_FLAG_SIMPLE_MODE.
	 */
	__le64 enable_gen;
} __attribute__ ((__packed__));

struct btrfs_qgroup_info_item {
	__le64 generation;
	__le64 rfer;
	__le64 rfer_cmpr;
	__le64 excl;
	__le64 excl_cmpr;
} __attribute__ ((__packed__));

struct btrfs_qgroup_limit_item {
	/*
	 * only updated when any of the other values change
	 */
	__le64 flags;
	__le64 max_rfer;
	__le64 max_excl;
	__le64 rsv_rfer;
	__le64 rsv_excl;
} __attribute__ ((__packed__));

struct btrfs_verity_descriptor_item {
	/* Size of the verity descriptor in bytes */
	__le64 size;
	/*
	 * When we implement support for fscrypt, we will need to encrypt the
	 * Merkle tree for encrypted verity files. These 128 bits are for the
	 * eventual storage of an fscrypt initialization vector.
	 */
	__le64 reserved[2];
	__u8 encryption;
} __attribute__ ((__packed__));

#endif /* _BTRFS_CTREE_H_ */