Struct Header 

pub struct Header {
    pub csum: [u8; 32],
    pub fsid: Uuid,
    pub bytenr: u64,
    pub flags: HeaderFlags,
    pub chunk_tree_uuid: Uuid,
    pub generation: u64,
    pub owner: u64,
    pub nritems: u32,
    pub level: u8,
}

Parsed header of a btrfs tree block (shared by nodes and leaves).

Every tree block (node or leaf) begins with this 101-byte header. It identifies the block’s position in the tree, its owning tree, and contains a checksum covering the entire block.

Fields

csum: [u8; 32]

Checksum of everything past this field to the end of the tree block.

fsid: Uuid

Filesystem UUID (must match the superblock’s fsid or metadata_uuid).

bytenr: u64

Logical byte offset where this block is stored.

flags: HeaderFlags

Header flags (lower 56 bits) and backref revision (upper 8 bits).

chunk_tree_uuid: Uuid

UUID of the chunk tree that maps this block’s logical address.

generation: u64

Transaction generation when this block was last written.

owner: u64

Objectid of the tree that owns this block (e.g. 1 = root tree, 5 = FS tree).

nritems: u32

Number of items (leaf) or key pointers (node) in this block.

level: u8

Tree level: 0 for leaves, >0 for internal nodes.

Implementations

impl Header

pub fn parse(buf: &[u8]) -> Self

Parse a tree block header from the start of buf.

Panics

Panics if buf is smaller than the on-disk header size (101 bytes).

pub fn backref_rev(&self) -> u64

Return the backref revision from the flags field.

pub fn block_flags(&self) -> HeaderFlags

Return the block flags with the backref revision bits masked out.

Trait Implementations

impl Clone for Header

fn clone(&self) -> Header

Returns a duplicate of the value.

fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for Header

fn fmt(&self, f: &mut Formatter<'_>) -> Result

Formats the value using the given formatter.