Re: [PATCH 7/8] btrfs: uapi/linux/btrfs_tree.h migration, item types and defines

From: Liu Bo <bo.li.liu@oracle.com>
To: Jeff Mahoney <jeffm@suse.com>
Cc: Btrfs Development List <linux-btrfs@vger.kernel.org>
Subject: Re: [PATCH 7/8] btrfs: uapi/linux/btrfs_tree.h migration, item types and defines
Date: Wed, 27 Apr 2016 14:12:07 -0700	[thread overview]
Message-ID: <20160427211207.GJ15822@localhost.localdomain> (raw)
In-Reply-To: <1459541670-4097-8-git-send-email-jeffm@suse.com>

On Fri, Apr 01, 2016 at 04:14:29PM -0400, Jeff Mahoney wrote:
> The BTRFS_IOC_SEARCH_TREE ioctl returns file system items directly
> to userspace.  In order to decode them, full type information is required.
> 
> Create a new header, btrfs_tree to contain these since most users won't
> need them.

Looks good to me.
Reviewed-by: Liu Bo <bo.li.liu@oracle.com>

Thanks,

-liubo
> 
> Signed-off-by: Jeff Mahoney <jeffm@suse.com>
> ---
>  fs/btrfs/ctree.h                | 949 +--------------------------------------
>  include/uapi/linux/btrfs_tree.h | 966 ++++++++++++++++++++++++++++++++++++++++
>  2 files changed, 967 insertions(+), 948 deletions(-)
>  create mode 100644 include/uapi/linux/btrfs_tree.h
> 
> diff --git a/fs/btrfs/ctree.h b/fs/btrfs/ctree.h
> index 89f36b6..cf34fb5 100644
> --- a/fs/btrfs/ctree.h
> +++ b/fs/btrfs/ctree.h
> @@ -33,6 +33,7 @@
>  #include <asm/kmap_types.h>
>  #include <linux/pagemap.h>
>  #include <linux/btrfs.h>
> +#include <linux/btrfs_tree.h>
>  #include <linux/workqueue.h>
>  #include <linux/security.h>
>  #include <linux/sizes.h>
> @@ -64,98 +65,6 @@ struct btrfs_ordered_sum;
>  
>  #define BTRFS_COMPAT_EXTENT_TREE_V0
>  
> -/* 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
> -
>  /*
>   * the max metadata block size.  This limit is somewhat artificial,
>   * but the memmove costs go through the roof for larger blocks.
> @@ -175,12 +84,6 @@ struct btrfs_ordered_sum;
>   */
>  #define BTRFS_LINK_MAX 65535U
>  
> -/* 32 bytes in various csum fields */
> -#define BTRFS_CSUM_SIZE 32
> -
> -/* csum types */
> -#define BTRFS_CSUM_TYPE_CRC32	0
> -
>  static const int btrfs_csum_sizes[] = { 4 };
>  
>  /* four bytes for CRC32 */
> @@ -189,17 +92,6 @@ static const int btrfs_csum_sizes[] = { 4 };
>  /* spefic to btrfs_map_block(), therefore not in include/linux/blk_types.h */
>  #define REQ_GET_READ_MIRRORS	(1 << 30)
>  
> -#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
> -
>  /* ioprio of readahead is set to idle */
>  #define BTRFS_IOPRIO_READA (IOPRIO_PRIO_VALUE(IOPRIO_CLASS_IDLE, 0))
>  
> @@ -207,138 +99,10 @@ static const int btrfs_csum_sizes[] = { 4 };
>  
>  #define BTRFS_MAX_EXTENT_SIZE SZ_128M
>  
> -/*
> - * 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__));
> -
>  struct btrfs_mapping_tree {
>  	struct extent_map_tree map_tree;
>  };
>  
> -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__));
> -
> -#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__));
> -
>  static inline unsigned long btrfs_chunk_item_size(int num_stripes)
>  {
>  	BUG_ON(num_stripes == 0);
> @@ -346,9 +110,6 @@ static inline unsigned long btrfs_chunk_item_size(int num_stripes)
>  		sizeof(struct btrfs_stripe) * (num_stripes - 1);
>  }
>  
> -#define BTRFS_HEADER_FLAG_WRITTEN	(1ULL << 0)
> -#define BTRFS_HEADER_FLAG_RELOC		(1ULL << 1)
> -
>  /*
>   * File system states
>   */
> @@ -357,13 +118,6 @@ static inline unsigned long btrfs_chunk_item_size(int num_stripes)
>  #define BTRFS_FS_STATE_TRANS_ABORTED	2
>  #define BTRFS_FS_STATE_DEV_REPLACING	3
>  
> -/* 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_BACKREF_REV_MAX		256
>  #define BTRFS_BACKREF_REV_SHIFT		56
>  #define BTRFS_BACKREF_REV_MASK		(((u64)BTRFS_BACKREF_REV_MAX - 1) << \
> @@ -598,357 +352,8 @@ struct btrfs_path {
>  	unsigned int need_commit_sem:1;
>  	unsigned int skip_release_on_error:1;
>  };
> -
> -/*
> - * 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_MAX_EXTENT_ITEM_SIZE(r) ((BTRFS_LEAF_DATA_SIZE(r) >> 4) - \
>  					sizeof(struct btrfs_item))
> -
> -#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_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 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[0];
> -	/* 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__));
> -
> -/*
> - * 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__));
> -
> -#define BTRFS_FILE_EXTENT_INLINE 0
> -#define BTRFS_FILE_EXTENT_REG 1
> -#define BTRFS_FILE_EXTENT_PREALLOC 2
> -
> -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
> -#define BTRFS_DEV_REPLACE_ITEM_STATE_NEVER_STARTED	0
> -#define BTRFS_DEV_REPLACE_ITEM_STATE_STARTED		1
> -#define BTRFS_DEV_REPLACE_ITEM_STATE_SUSPENDED		2
> -#define BTRFS_DEV_REPLACE_ITEM_STATE_FINISHED		3
> -#define BTRFS_DEV_REPLACE_ITEM_STATE_CANCELED		4
> -
>  struct btrfs_dev_replace {
>  	u64 replace_state;	/* see #define above */
>  	u64 time_started;	/* seconds since 1-Jan-1970 */
> @@ -979,167 +384,6 @@ struct btrfs_dev_replace {
>  	struct btrfs_scrub_progress scrub_progress;
>  };
>  
> -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_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)
> -
> -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)
> -/*
> - * 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)
> -
> -#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__));
> -
> -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__));
> -
>  /* For raid type sysfs entries */
>  struct raid_kobject {
>  	int raid_type;
> @@ -1992,197 +1236,6 @@ struct btrfs_root {
>  	atomic_t qgroup_meta_rsv;
>  };
>  
> -
> -/*
> - * 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
> -
>  /*
>   * Flags for mount options.
>   *
> diff --git a/include/uapi/linux/btrfs_tree.h b/include/uapi/linux/btrfs_tree.h
> new file mode 100644
> index 0000000..1e87505
> --- /dev/null
> +++ b/include/uapi/linux/btrfs_tree.h
> @@ -0,0 +1,966 @@
> +#ifndef _BTRFS_CTREE_H_
> +#define _BTRFS_CTREE_H_
> +
> +/*
> + * 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.
> + *
> + * 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;
> +
> +	/* 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__));
> +
> +#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)
> +
> +
> +/*
> + * 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)
> +
> +/*
> + * 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 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[0];
> +	/* 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__));
> +
> +/*
> + * 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__));
> +
> +#define BTRFS_FILE_EXTENT_INLINE 0
> +#define BTRFS_FILE_EXTENT_REG 1
> +#define BTRFS_FILE_EXTENT_PREALLOC 2
> +
> +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
> +#define BTRFS_DEV_REPLACE_ITEM_STATE_NEVER_STARTED	0
> +#define BTRFS_DEV_REPLACE_ITEM_STATE_STARTED		1
> +#define BTRFS_DEV_REPLACE_ITEM_STATE_SUSPENDED		2
> +#define BTRFS_DEV_REPLACE_ITEM_STATE_FINISHED		3
> +#define BTRFS_DEV_REPLACE_ITEM_STATE_CANCELED		4
> +
> +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_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)
> +
> +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)
> +/*
> + * 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)
> +
> +#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__));
> +
> +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__));
> +
> +#endif /* _BTRFS_CTREE_H_ */
> -- 
> 2.7.1
> 
> --
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