diff --git a/fs/btrfs/btrfs.c b/fs/btrfs/btrfs.c
index de16217..9f2888b 100644
--- a/fs/btrfs/btrfs.c
+++ b/fs/btrfs/btrfs.c
@@ -32,7 +32,8 @@
 	char filetime[32], *target = NULL;
 	time_t mtime;
 
-	if (btrfs_lookup_inode(root, &item->location, &inode, NULL)) {
+	if (btrfs_lookup_inode(root, (struct btrfs_key *)&item->location,
+			       &inode, NULL)) {
 		printf("%s: Cannot find inode item for directory entry %.*s!\n",
 		       __func__, item->name_len, name);
 		return 0;
diff --git a/fs/btrfs/btrfs_tree.h b/fs/btrfs/btrfs_tree.h
deleted file mode 100644
index aa0f3d6..0000000
--- a/fs/btrfs/btrfs_tree.h
+++ /dev/null
@@ -1,766 +0,0 @@
-/* SPDX-License-Identifier: GPL-2.0+ */
-/*
- * From linux/include/uapi/linux/btrfs_tree.h
- */
-
-#ifndef __BTRFS_BTRFS_TREE_H__
-#define __BTRFS_BTRFS_TREE_H__
-
-#include <common.h>
-
-#define BTRFS_VOL_NAME_MAX 255
-#define BTRFS_NAME_MAX 255
-#define BTRFS_LABEL_SIZE 256
-#define BTRFS_FSID_SIZE 16
-#define BTRFS_UUID_SIZE 16
-
-/*
- * 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
-
-/* 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
-
-/* orhpan 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
-#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.
- */
-#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
-
-#define BTRFS_TREE_BLOCK_REF_KEY	176
-
-#define BTRFS_EXTENT_DATA_REF_KEY	178
-
-#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
-
-/*
- * 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
-
-/*
- * Persistantly 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
-
-
-
-/* 32 bytes in various csum fields */
-#define BTRFS_CSUM_SIZE 32
-
-/* csum types */
-#define BTRFS_CSUM_TYPE_CRC32	0
-
-/*
- * flags definitions for directory entry item type
- *
- * Used by:
- * struct btrfs_dir_item.type
- */
-#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
-
-/*
- * 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.
- */
-
-struct btrfs_key {
-	__u64 objectid;
-	__u8 type;
-	__u64 offset;
-} __attribute__ ((__packed__));
-
-struct btrfs_dev_item {
-	/* the internal btrfs device id */
-	__u64 devid;
-
-	/* size of the device */
-	__u64 total_bytes;
-
-	/* bytes used */
-	__u64 bytes_used;
-
-	/* optimal io alignment for this device */
-	__u32 io_align;
-
-	/* optimal io width for this device */
-	__u32 io_width;
-
-	/* minimal io size for this device */
-	__u32 sector_size;
-
-	/* type and info about this device */
-	__u64 type;
-
-	/* expected generation for this device */
-	__u64 generation;
-
-	/*
-	 * starting byte of this partition on the device,
-	 * to allow for stripe alignment in the future
-	 */
-	__u64 start_offset;
-
-	/* grouping information for allocation decisions */
-	__u32 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 {
-	__u64 devid;
-	__u64 offset;
-	__u8 dev_uuid[BTRFS_UUID_SIZE];
-} __attribute__ ((__packed__));
-
-struct btrfs_chunk {
-	/* size of this chunk in bytes */
-	__u64 length;
-
-	/* objectid of the root referencing this chunk */
-	__u64 owner;
-
-	__u64 stripe_len;
-	__u64 type;
-
-	/* optimal io alignment for this chunk */
-	__u32 io_align;
-
-	/* optimal io width for this chunk */
-	__u32 io_width;
-
-	/* minimal io size for this chunk */
-	__u32 sector_size;
-
-	/* 2^16 stripes is quite a lot, a second limit is the size of a single
-	 * item in the btree
-	 */
-	__u16 num_stripes;
-
-	/* sub stripes only matter for raid10 */
-	__u16 sub_stripes;
-	struct btrfs_stripe stripe;
-	/* additional stripes go here */
-} __attribute__ ((__packed__));
-
-#define BTRFS_FREE_SPACE_EXTENT	1
-#define BTRFS_FREE_SPACE_BITMAP	2
-
-struct btrfs_free_space_entry {
-	__u64 offset;
-	__u64 bytes;
-	__u8 type;
-} __attribute__ ((__packed__));
-
-struct btrfs_free_space_header {
-	struct btrfs_key location;
-	__u64 generation;
-	__u64 num_entries;
-	__u64 num_bitmaps;
-} __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)
-
-
-/*
- * 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 {
-	__u64 refs;
-	__u64 generation;
-	__u64 flags;
-} __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)
-
-/*
- * 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_key key;
-	__u8 level;
-} __attribute__ ((__packed__));
-
-struct btrfs_extent_data_ref {
-	__u64 root;
-	__u64 objectid;
-	__u64 offset;
-	__u32 count;
-} __attribute__ ((__packed__));
-
-struct btrfs_shared_data_ref {
-	__u32 count;
-} __attribute__ ((__packed__));
-
-struct btrfs_extent_inline_ref {
-	__u8 type;
-	__u64 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 {
-	__u64 chunk_tree;
-	__u64 chunk_objectid;
-	__u64 chunk_offset;
-	__u64 length;
-	__u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
-} __attribute__ ((__packed__));
-
-struct btrfs_inode_ref {
-	__u64 index;
-	__u16 name_len;
-	/* name goes here */
-} __attribute__ ((__packed__));
-
-struct btrfs_inode_extref {
-	__u64 parent_objectid;
-	__u64 index;
-	__u16 name_len;
-	__u8   name[0];
-	/* name goes here */
-} __attribute__ ((__packed__));
-
-struct btrfs_timespec {
-	__u64 sec;
-	__u32 nsec;
-} __attribute__ ((__packed__));
-
-struct btrfs_inode_item {
-	/* nfs style generation number */
-	__u64 generation;
-	/* transid that last touched this inode */
-	__u64 transid;
-	__u64 size;
-	__u64 nbytes;
-	__u64 block_group;
-	__u32 nlink;
-	__u32 uid;
-	__u32 gid;
-	__u32 mode;
-	__u64 rdev;
-	__u64 flags;
-
-	/* modification sequence number for NFS */
-	__u64 sequence;
-
-	/*
-	 * a little future expansion, for more than this we can
-	 * just grow the inode item and version it
-	 */
-	__u64 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 {
-	__u64 end;
-} __attribute__ ((__packed__));
-
-struct btrfs_dir_item {
-	struct btrfs_key location;
-	__u64 transid;
-	__u16 data_len;
-	__u16 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;
-	__u64 generation;
-	__u64 root_dirid;
-	__u64 bytenr;
-	__u64 byte_limit;
-	__u64 bytes_used;
-	__u64 last_snapshot;
-	__u64 flags;
-	__u32 refs;
-	struct btrfs_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.
-	 */
-	__u64 generation_v2;
-	__u8 uuid[BTRFS_UUID_SIZE];
-	__u8 parent_uuid[BTRFS_UUID_SIZE];
-	__u8 received_uuid[BTRFS_UUID_SIZE];
-	__u64 ctransid; /* updated when an inode changes */
-	__u64 otransid; /* trans when created */
-	__u64 stransid; /* trans when sent. non-zero for received subvol */
-	__u64 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;
-	__u64 reserved[8]; /* for future */
-} __attribute__ ((__packed__));
-
-/*
- * this is used for both forward and backward root refs
- */
-struct btrfs_root_ref {
-	__u64 dirid;
-	__u64 sequence;
-	__u16 name_len;
-} __attribute__ ((__packed__));
-
-#define BTRFS_FILE_EXTENT_INLINE 0
-#define BTRFS_FILE_EXTENT_REG 1
-#define BTRFS_FILE_EXTENT_PREALLOC 2
-
-enum btrfs_compression_type {
-	BTRFS_COMPRESS_NONE  = 0,
-	BTRFS_COMPRESS_ZLIB  = 1,
-	BTRFS_COMPRESS_LZO   = 2,
-	BTRFS_COMPRESS_ZSTD  = 3,
-	BTRFS_COMPRESS_TYPES = 3,
-	BTRFS_COMPRESS_LAST  = 4,
-};
-
-struct btrfs_file_extent_item {
-	/*
-	 * transaction id that created this extent
-	 */
-	__u64 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.
-	 */
-	__u64 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;
-	__u16 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.
-	 */
-	__u64 disk_bytenr;
-	__u64 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
-	 */
-	__u64 offset;
-	/*
-	 * the logical number of file blocks (no csums included).  This
-	 * always reflects the size uncompressed and without encoding.
-	 */
-	__u64 num_bytes;
-
-} __attribute__ ((__packed__));
-
-struct btrfs_csum_item {
-	__u8 csum;
-} __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_RESERVED	(BTRFS_AVAIL_ALLOC_BIT_SINGLE | \
-					 BTRFS_SPACE_INFO_GLOBAL_RSV)
-
-enum btrfs_raid_types {
-	BTRFS_RAID_RAID10,
-	BTRFS_RAID_RAID1,
-	BTRFS_RAID_DUP,
-	BTRFS_RAID_RAID0,
-	BTRFS_RAID_SINGLE,
-	BTRFS_RAID_RAID5,
-	BTRFS_RAID_RAID6,
-	BTRFS_NR_RAID_TYPES
-};
-
-#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_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)
-
-/*
- * 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)
-
-#endif /* __BTRFS_BTRFS_TREE_H__ */
diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
index 65c152a..156ce69 100644
--- a/fs/btrfs/ctree.h
+++ b/fs/btrfs/ctree.h
@@ -11,16 +11,10 @@
 
 #include <common.h>
 #include <compiler.h>
-#include "btrfs_tree.h"
-
-#define BTRFS_MAGIC 0x4D5F53665248425FULL /* ascii _BHRfS_M, no null */
+#include "kernel-shared/btrfs_tree.h"
 
 #define BTRFS_MAX_MIRRORS 3
 
-#define BTRFS_MAX_LEVEL 8
-
-#define BTRFS_COMPAT_EXTENT_TREE_V0
-
 /*
  * the max metadata block size.  This limit is somewhat artificial,
  * but the memmove costs go through the roof for larger blocks.
@@ -28,20 +22,12 @@
 #define BTRFS_MAX_METADATA_BLOCKSIZE 65536
 
 /*
- * 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
 
-static const int btrfs_csum_sizes[] = { 4 };
-
 /* four bytes for CRC32 */
 #define BTRFS_EMPTY_DIR_SIZE 0
 
@@ -61,207 +47,12 @@
 #define BTRFS_FS_STATE_DEV_REPLACING	3
 #define BTRFS_FS_STATE_DUMMY_FS_INFO	4
 
-#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
-
-/*
- * 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];
-	__u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */
-	__u64 bytenr; /* which block this node is supposed to live in */
-	__u64 flags;
-
-	/* allowed to be different from the super from here on down */
-	__u8 chunk_tree_uuid[BTRFS_UUID_SIZE];
-	__u64 generation;
-	__u64 owner;
-	__u32 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 {
-	__u64 tree_root;
-	__u64 tree_root_gen;
-
-	__u64 chunk_root;
-	__u64 chunk_root_gen;
-
-	__u64 extent_root;
-	__u64 extent_root_gen;
-
-	__u64 fs_root;
-	__u64 fs_root_gen;
-
-	__u64 dev_root;
-	__u64 dev_root_gen;
-
-	__u64 csum_root;
-	__u64 csum_root_gen;
-
-	__u64 total_bytes;
-	__u64 bytes_used;
-	__u64 num_devices;
-	/* future */
-	__u64 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__));
-
-/*
- * the super block basically lists the main trees of the FS
- * it currently lacks any block count etc etc
- */
-struct btrfs_super_block {
-	__u8 csum[BTRFS_CSUM_SIZE];
-	/* the first 4 fields must match struct btrfs_header */
-	__u8 fsid[BTRFS_FSID_SIZE];    /* FS specific uuid */
-	__u64 bytenr; /* this block number */
-	__u64 flags;
-
-	/* allowed to be different from the btrfs_header from here own down */
-	__u64 magic;
-	__u64 generation;
-	__u64 root;
-	__u64 chunk_root;
-	__u64 log_root;
-
-	/* this will help find the new super based on the log root */
-	__u64 log_root_transid;
-	__u64 total_bytes;
-	__u64 bytes_used;
-	__u64 root_dir_objectid;
-	__u64 num_devices;
-	__u32 sectorsize;
-	__u32 nodesize;
-	__u32 __unused_leafsize;
-	__u32 stripesize;
-	__u32 sys_chunk_array_size;
-	__u64 chunk_root_generation;
-	__u64 compat_flags;
-	__u64 compat_ro_flags;
-	__u64 incompat_flags;
-	__u16 csum_type;
-	__u8 root_level;
-	__u8 chunk_root_level;
-	__u8 log_root_level;
-	struct btrfs_dev_item dev_item;
-
-	char label[BTRFS_LABEL_SIZE];
-
-	__u64 cache_generation;
-	__u64 uuid_tree_generation;
-
-	/* future expansion */
-	__u64 reserved[30];
-	__u8 sys_chunk_array[BTRFS_SYSTEM_CHUNK_ARRAY_SIZE];
-	struct btrfs_root_backup super_roots[BTRFS_NUM_BACKUP_ROOTS];
-} __attribute__ ((__packed__));
-
-/*
- * Compat flags that we support.  If any incompat flags are set other than the
- * ones specified below then we will fail to mount
- */
-#define BTRFS_FEATURE_COMPAT_SUPP		0ULL
-#define BTRFS_FEATURE_COMPAT_SAFE_SET		0ULL
-#define BTRFS_FEATURE_COMPAT_SAFE_CLEAR		0ULL
-
-#define BTRFS_FEATURE_COMPAT_RO_SUPP			\
-	(BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE |	\
-	 BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE_VALID)
-
-#define BTRFS_FEATURE_COMPAT_RO_SAFE_SET	0ULL
-#define BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR	0ULL
-
-#define BTRFS_FEATURE_INCOMPAT_SUPP			\
-	(BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF |		\
-	 BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL |	\
-	 BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS |		\
-	 BTRFS_FEATURE_INCOMPAT_BIG_METADATA |		\
-	 BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO |		\
-	 BTRFS_FEATURE_INCOMPAT_RAID56 |		\
-	 BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF |		\
-	 BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA |	\
-	 BTRFS_FEATURE_INCOMPAT_NO_HOLES)
-
-#define BTRFS_FEATURE_INCOMPAT_SAFE_SET			\
-	(BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF)
-#define BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR		0ULL
-
-/*
- * 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_key key;
-	__u32 offset;
-	__u32 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_key key;
-	__u64 blockptr;
-	__u64 generation;
-} __attribute__ ((__packed__));
-
-struct btrfs_node {
-	struct btrfs_header header;
-	struct btrfs_key_ptr ptrs[];
-} __attribute__ ((__packed__));
-
 union btrfs_tree_node {
 	struct btrfs_header header;
 	struct btrfs_leaf leaf;
 	struct btrfs_node node;
 };
 
-typedef __u8 u8;
-typedef __u16 u16;
-typedef __u32 u32;
-typedef __u64 u64;
-
 struct btrfs_path {
 	union btrfs_tree_node *nodes[BTRFS_MAX_LEVEL];
 	u32 slots[BTRFS_MAX_LEVEL];
@@ -283,7 +74,8 @@
 int btrfs_next_slot(struct btrfs_path *);
 
 static inline struct btrfs_key *btrfs_path_leaf_key(struct btrfs_path *p) {
-	return &p->nodes[0]->leaf.items[p->slots[0]].key;
+	/* At tree read time we have converted the endian for btrfs_disk_key */
+	return (struct btrfs_key *)&p->nodes[0]->leaf.items[p->slots[0]].key;
 }
 
 static inline struct btrfs_key *
diff --git a/fs/btrfs/inode.c b/fs/btrfs/inode.c
index 991c2f6..d88ae67 100644
--- a/fs/btrfs/inode.c
+++ b/fs/btrfs/inode.c
@@ -29,7 +29,7 @@
 		*refp = *ref;
 
 	if (name) {
-		if (ref->name_len > BTRFS_NAME_MAX) {
+		if (ref->name_len > BTRFS_NAME_LEN) {
 			printf("%s: inode name too long: %u\n", __func__,
 			        ref->name_len);
 			goto out;
@@ -255,7 +255,8 @@
 
 		type = item.type;
 		have_inode = 1;
-		if (btrfs_lookup_inode(root, &item.location, &inode_item, root))
+		if (btrfs_lookup_inode(root, (struct btrfs_key *)&item.location,
+					&inode_item, root))
 			return -1ULL;
 
 		if (item.type == BTRFS_FT_SYMLINK && symlink_limit >= 0) {
diff --git a/fs/btrfs/kernel-shared/btrfs_tree.h b/fs/btrfs/kernel-shared/btrfs_tree.h
new file mode 100644
index 0000000..6a76d1e
--- /dev/null
+++ b/fs/btrfs/kernel-shared/btrfs_tree.h
@@ -0,0 +1,1333 @@
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+/*
+ * Copied from kernel/include/uapi/linux/btrfs_btree.h.
+ *
+ * Only modified the header.
+ */
+/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */
+#ifndef __BTRFS_TREE_H__
+#define __BTRFS_TREE_H__
+
+#include <linux/types.h>
+
+#define BTRFS_MAGIC 0x4D5F53665248425FULL /* ascii _BHRfS_M, no null */
+
+/*
+ * The max metadata block size (node size).
+ *
+ * This limit is somewhat artificial. The memmove and tree block locking cost
+ * go up with larger node size.
+ */
+#define BTRFS_MAX_METADATA_BLOCKSIZE 65536
+
+/*
+ * We can actually store much bigger names, but lets not confuse the rest
+ * of linux.
+ *
+ * btrfs_dir_item::name_len follows this limitation.
+ */
+#define BTRFS_NAME_LEN 255
+
+/*
+ * Objectids start from here.
+ *
+ * Check btrfs_disk_key for the meaning of objectids.
+ */
+
+/*
+ * Root tree holds pointers to all of the tree roots.
+ * Without special mention, the root tree contains the root bytenr of all other
+ * trees, except the chunk tree and the log tree.
+ *
+ * The super block contains the root bytenr of this tree.
+ */
+#define BTRFS_ROOT_TREE_OBJECTID 1ULL
+
+/*
+ * Extent tree stores information about which extents are in use, and backrefs
+ * for each extent.
+ */
+#define BTRFS_EXTENT_TREE_OBJECTID 2ULL
+
+/*
+ * Chunk tree stores btrfs logical address -> physical address mapping.
+ *
+ * The super block contains part of chunk tree for bootstrap, and contains
+ * the root bytenr of this tree.
+ */
+#define BTRFS_CHUNK_TREE_OBJECTID 3ULL
+
+/*
+ * Device tree stores info about which areas of a given device are in use,
+ * and physical address -> btrfs logical address mapping.
+ */
+#define BTRFS_DEV_TREE_OBJECTID 4ULL
+
+/* The fs tree is the first subvolume tree, storing files and directories. */
+#define BTRFS_FS_TREE_OBJECTID 5ULL
+
+/* Shows the directory objectid inside the root tree. */
+#define BTRFS_ROOT_TREE_DIR_OBJECTID 6ULL
+
+/* Csum tree holds checksums of all the data extents. */
+#define BTRFS_CSUM_TREE_OBJECTID 7ULL
+
+/* Quota tree holds quota configuration and tracking. */
+#define BTRFS_QUOTA_TREE_OBJECTID 8ULL
+
+/* UUID tree stores items that use the BTRFS_UUID_KEY* types. */
+#define BTRFS_UUID_TREE_OBJECTID 9ULL
+
+/* Free space cache tree (v2 space cache) tracks free space in block groups. */
+#define BTRFS_FREE_SPACE_TREE_OBJECTID 10ULL
+
+/* Indicates 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
+
+/* Orhpan 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, shared between the csum tree and log trees. */
+#define BTRFS_EXTENT_CSUM_OBJECTID -10ULL
+
+/* For storing free space cache (v1 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
+ * (BTRFS_DEV_ITEMS_OBJECTID, 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
+
+/*
+ * Types start from here.
+ *
+ * Check btrfs_disk_key for details about types.
+ */
+
+/*
+ * 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
+/* reserve 2-11 close to the inode for later flexibility */
+#define BTRFS_INODE_REF_KEY		12
+#define BTRFS_INODE_EXTREF_KEY		13
+#define BTRFS_XATTR_ITEM_KEY		24
+#define BTRFS_ORPHAN_ITEM_KEY		48
+
+/*
+ * Dir items are the name -> inode pointers in a directory.
+ *
+ * There is one for every name in a directory.
+ */
+#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
+
+/* Stores info (position, size ...) about a data extent of a file */
+#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 tree.
+ *
+ * These record which blocks are used, and how many references there are.
+ */
+#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
+
+#define BTRFS_TREE_BLOCK_REF_KEY	176
+
+#define BTRFS_EXTENT_DATA_REF_KEY	178
+
+#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.
+ *
+ * Stores how many free space there is in a block group.
+ */
+#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
+
+/*
+ * 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).
+ */
+#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
+
+
+
+/* 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
+
+#define BTRFS_FSID_SIZE 16
+#define BTRFS_UUID_SIZE 16
+
+/*
+ * The key defines the order in the tree, and so it also defines (optimal)
+ * block layout.
+ *
+ * Objectid and offset are interpreted based on type.
+ * While normally for objectid, it either represents a root number, or an
+ * inode number.
+ *
+ * Type tells us things about the object, and is a kind of stream selector.
+ * Check the following URL for full references about btrfs_disk_key/btrfs_key:
+ * https://btrfs.wiki.kernel.org/index.php/Btree_Items
+ *
+ * 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__));
+
+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;
+
+	/* Optimal seek speed 0-100 where 100 is fastest */
+	__u8 seek_speed;
+
+	/* Optimal 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__));
+
+#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__));
+
+#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 tree 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)
+
+/* Use full backrefs for extent pointers in the block */
+#define BTRFS_BLOCK_FLAG_FULL_BACKREF	(1ULL << 8)
+
+/*
+ * 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_inline_ref {
+	__u8 type;
+	__le64 offset;
+} __attribute__ ((__packed__));
+
+/* Old style backrefs item */
+struct btrfs_extent_ref_v0 {
+	__le64 root;
+	__le64 generation;
+	__le64 objectid;
+	__le32 count;
+} __attribute__ ((__packed__));
+
+
+/* Dev extents record used 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[0];
+	/* Name goes here */
+} __attribute__ ((__packed__));
+
+struct btrfs_timespec {
+	__le64 sec;
+	__le32 nsec;
+} __attribute__ ((__packed__));
+
+/* Inode flags */
+#define BTRFS_INODE_NODATASUM		(1 << 0)
+#define BTRFS_INODE_NODATACOW		(1 << 1)
+#define BTRFS_INODE_READONLY		(1 << 2)
+#define BTRFS_INODE_NOCOMPRESS		(1 << 3)
+#define BTRFS_INODE_PREALLOC		(1 << 4)
+#define BTRFS_INODE_SYNC		(1 << 5)
+#define BTRFS_INODE_IMMUTABLE		(1 << 6)
+#define BTRFS_INODE_APPEND		(1 << 7)
+#define BTRFS_INODE_NODUMP		(1 << 8)
+#define BTRFS_INODE_NOATIME		(1 << 9)
+#define BTRFS_INODE_DIRSYNC		(1 << 10)
+#define BTRFS_INODE_COMPRESS		(1 << 11)
+
+#define BTRFS_INODE_ROOT_ITEM_INIT	(1 << 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)
+
+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__));
+
+/* 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__));
+
+/*
+ * Stores 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,
+};
+
+enum btrfs_compression_type {
+	BTRFS_COMPRESS_NONE  = 0,
+	BTRFS_COMPRESS_ZLIB  = 1,
+	BTRFS_COMPRESS_LZO   = 2,
+	BTRFS_COMPRESS_ZSTD  = 3,
+	BTRFS_NR_COMPRESS_TYPES = 4,
+};
+
+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 not 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 inside the file extent.
+	 *
+	 * 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 bytes this file extent is referencing (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__));
+
+enum btrfs_dev_stat_values {
+	/* Disk I/O failure stats */
+	BTRFS_DEV_STAT_WRITE_ERRS, /* EIO or EREMOTEIO from lower layers */
+	BTRFS_DEV_STAT_READ_ERRS, /* EIO or EREMOTEIO from lower layers */
+	BTRFS_DEV_STAT_FLUSH_ERRS, /* EIO or EREMOTEIO from lower layers */
+
+	/* Stats for indirect indications for I/O failures */
+	BTRFS_DEV_STAT_CORRUPTION_ERRS, /* Checksum error, bytenr error or
+					 * contents is illegal: this is an
+					 * indication that the block was damaged
+					 * during read or write, or written to
+					 * wrong location or read from wrong
+					 * location */
+	BTRFS_DEV_STAT_GENERATION_ERRS, /* An indication that blocks have not
+					 * been written */
+
+	BTRFS_DEV_STAT_VALUES_MAX
+};
+
+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)
+
+enum btrfs_raid_types {
+	BTRFS_RAID_RAID10,
+	BTRFS_RAID_RAID1,
+	BTRFS_RAID_DUP,
+	BTRFS_RAID_RAID0,
+	BTRFS_RAID_SINGLE,
+	BTRFS_RAID_RAID5,
+	BTRFS_RAID_RAID6,
+	BTRFS_RAID_RAID1C3,
+	BTRFS_RAID_RAID1C4,
+	BTRFS_NR_RAID_TYPES
+};
+
+#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 __u64 btrfs_qgroup_level(__u64 qgroupid)
+{
+	return qgroupid >> BTRFS_QGROUP_LEVEL_SHIFT;
+}
+
+/* Is subvolume quota turned on? */
+#define BTRFS_QGROUP_STATUS_FLAG_ON		(1ULL << 0)
+
+/* Is qgroup rescan running? */
+#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.
+ */
+#define BTRFS_QGROUP_STATUS_FLAG_INCONSISTENT	(1ULL << 2)
+
+#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;
+} __attribute__ ((__packed__));
+
+struct btrfs_qgroup_info_item {
+	__le64 generation;
+	__le64 rfer;
+	__le64 rfer_cmpr;
+	__le64 excl;
+	__le64 excl_cmpr;
+} __attribute__ ((__packed__));
+
+/*
+ * Flags definition for qgroup limits
+ *
+ * Used by:
+ * struct btrfs_qgroup_limit.flags
+ * struct btrfs_qgroup_limit_item.flags
+ */
+#define BTRFS_QGROUP_LIMIT_MAX_RFER	(1ULL << 0)
+#define BTRFS_QGROUP_LIMIT_MAX_EXCL	(1ULL << 1)
+#define BTRFS_QGROUP_LIMIT_RSV_RFER	(1ULL << 2)
+#define BTRFS_QGROUP_LIMIT_RSV_EXCL	(1ULL << 3)
+#define BTRFS_QGROUP_LIMIT_RFER_CMPR	(1ULL << 4)
+#define BTRFS_QGROUP_LIMIT_EXCL_CMPR	(1ULL << 5)
+
+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__));
+
+/*
+ * 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__));
+
+/*
+ * 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
+
+#define BTRFS_LABEL_SIZE 256
+
+/* 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];
+	__le64 bytenr; /* this block number */
+	__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 will help find the new super based on the log root. */
+	__le64 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];
+
+	/* Future expansion */
+	__le64 reserved[28];
+	u8 sys_chunk_array[BTRFS_SYSTEM_CHUNK_ARRAY_SIZE];
+	struct btrfs_root_backup super_roots[BTRFS_NUM_BACKUP_ROOTS];
+} __attribute__ ((__packed__));
+
+/*
+ * Feature flags
+ *
+ * Used by:
+ * struct btrfs_super_block::(compat|compat_ro|incompat)_flags
+ * struct btrfs_ioctl_feature_flags
+ */
+#define BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE		(1ULL << 0)
+
+/*
+ * Older kernels (< 4.9) on big-endian systems produced broken free space tree
+ * bitmaps, and btrfs-progs also used to corrupt the free space tree (versions
+ * < 4.7.3).  If this bit is clear, then the free space tree cannot be trusted.
+ * btrfs-progs can also intentionally clear this bit to ask the kernel to
+ * rebuild the free space tree, however this might not work on older kernels
+ * that do not know about this bit. If not sure, clear the cache manually on
+ * first mount when booting older kernel versions.
+ */
+#define BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE_VALID	(1ULL << 1)
+
+#define BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF	(1ULL << 0)
+#define BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL	(1ULL << 1)
+#define BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS	(1ULL << 2)
+#define BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO	(1ULL << 3)
+#define BTRFS_FEATURE_INCOMPAT_COMPRESS_ZSTD	(1ULL << 4)
+
+/*
+ * Older kernels tried to do bigger metadata blocks, but the
+ * code was pretty buggy.  Lets not let them try anymore.
+ */
+#define BTRFS_FEATURE_INCOMPAT_BIG_METADATA	(1ULL << 5)
+
+#define BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF	(1ULL << 6)
+#define BTRFS_FEATURE_INCOMPAT_RAID56		(1ULL << 7)
+#define BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA	(1ULL << 8)
+#define BTRFS_FEATURE_INCOMPAT_NO_HOLES		(1ULL << 9)
+#define BTRFS_FEATURE_INCOMPAT_METADATA_UUID	(1ULL << 10)
+#define BTRFS_FEATURE_INCOMPAT_RAID1C34		(1ULL << 11)
+
+/*
+ * Compat flags that we support.
+ *
+ * If any incompat flags are set other than the ones specified below then we
+ * will fail to mount.
+ */
+#define BTRFS_FEATURE_COMPAT_SUPP		0ULL
+#define BTRFS_FEATURE_COMPAT_SAFE_SET		0ULL
+#define BTRFS_FEATURE_COMPAT_SAFE_CLEAR		0ULL
+
+#define BTRFS_FEATURE_COMPAT_RO_SUPP			\
+	(BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE |	\
+	 BTRFS_FEATURE_COMPAT_RO_FREE_SPACE_TREE_VALID)
+
+#define BTRFS_FEATURE_COMPAT_RO_SAFE_SET	0ULL
+#define BTRFS_FEATURE_COMPAT_RO_SAFE_CLEAR	0ULL
+
+#define BTRFS_FEATURE_INCOMPAT_SUPP			\
+	(BTRFS_FEATURE_INCOMPAT_MIXED_BACKREF |		\
+	 BTRFS_FEATURE_INCOMPAT_DEFAULT_SUBVOL |	\
+	 BTRFS_FEATURE_INCOMPAT_MIXED_GROUPS |		\
+	 BTRFS_FEATURE_INCOMPAT_BIG_METADATA |		\
+	 BTRFS_FEATURE_INCOMPAT_COMPRESS_LZO |		\
+	 BTRFS_FEATURE_INCOMPAT_COMPRESS_ZSTD |		\
+	 BTRFS_FEATURE_INCOMPAT_RAID56 |		\
+	 BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF |		\
+	 BTRFS_FEATURE_INCOMPAT_SKINNY_METADATA |	\
+	 BTRFS_FEATURE_INCOMPAT_NO_HOLES	|	\
+	 BTRFS_FEATURE_INCOMPAT_METADATA_UUID	|	\
+	 BTRFS_FEATURE_INCOMPAT_RAID1C34)
+
+#define BTRFS_FEATURE_INCOMPAT_SAFE_SET			\
+	(BTRFS_FEATURE_INCOMPAT_EXTENDED_IREF)
+#define BTRFS_FEATURE_INCOMPAT_SAFE_CLEAR		0ULL
+
+#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
+
+#define BTRFS_MAX_LEVEL 8
+
+/* 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];
+	u8 fsid[BTRFS_FSID_SIZE]; /* FS specific uuid */
+	__le64 bytenr; /* Which block this node is supposed to live in */
+	__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__));
+
+/*
+ * 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 children
+ * 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__));
+
+#endif /* __BTRFS_TREE_H__ */
diff --git a/fs/btrfs/root.c b/fs/btrfs/root.c
index 127b67f..61155e8 100644
--- a/fs/btrfs/root.c
+++ b/fs/btrfs/root.c
@@ -75,7 +75,7 @@
 		*refp = *ref;
 
 	if (name) {
-		if (ref->name_len > BTRFS_VOL_NAME_MAX) {
+		if (ref->name_len > BTRFS_NAME_LEN) {
 			printf("%s: volume name too long: %u\n", __func__,
 			       ref->name_len);
 			goto out;
diff --git a/fs/btrfs/subvolume.c b/fs/btrfs/subvolume.c
index 06e54f3..dbe92d1 100644
--- a/fs/btrfs/subvolume.c
+++ b/fs/btrfs/subvolume.c
@@ -14,7 +14,7 @@
 	struct btrfs_inode_ref iref;
 	struct btrfs_root root;
 	u64 dir;
-	char tmp[max(BTRFS_VOL_NAME_MAX, BTRFS_NAME_MAX)];
+	char tmp[BTRFS_NAME_LEN];
 	char *ptr;
 
 	ptr = name + max_len - 1;