md/raid1: only allocate write behind bio for WriteMostly device

[linux.git] / include / uapi / linux / btrfs_tree.h

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

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

/*
 * 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

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

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

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

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

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

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

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

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


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

#define BTRFS_BTREE_INODE_OBJECTID 1

#define BTRFS_EMPTY_SUBVOL_DIR_OBJECTID 2

#define BTRFS_DEV_REPLACE_DEVID 0ULL

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

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

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

/*
 * dir items are the name -> inode pointers in a directory.  There is one
 * for every name in a directory.
 */
#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

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

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

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

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

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

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

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

/*
 * 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)
#define BTRFS_SUPER_FLAG_METADUMP_V2    (1ULL << 34)
#define BTRFS_SUPER_FLAG_CHANGING_FSID  (1ULL << 35)
#define BTRFS_SUPER_FLAG_CHANGING_FSID_V2 (1ULL << 36)


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

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

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


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

/* following flags only apply to tree blocks */

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

/*
 * 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__));

/* 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__));

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

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

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

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

        /* devid filter */
        __le64 devid;

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

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

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

        /* BTRFS_BALANCE_ARGS_* */
        __le64 flags;

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

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

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

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

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

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

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

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

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

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

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

} __attribute__ ((__packed__));

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

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

#define BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_ALWAYS     0
#define BTRFS_DEV_REPLACE_ITEM_CONT_READING_FROM_SRCDEV_MODE_AVOID      1

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

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

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

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 __u16 btrfs_qgroup_level(__u64 qgroupid)
{
        return (__u16)(qgroupid >> BTRFS_QGROUP_LEVEL_SHIFT);
}

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

#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__));

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

#endif /* _BTRFS_CTREE_H_ */