Struct FileExtentItem 

pub struct FileExtentItem {
    pub generation: u64,
    pub ram_bytes: u64,
    pub compression: CompressionType,
    pub extent_type: FileExtentType,
    pub body: FileExtentBody,
}

File extent descriptor, stored as EXTENT_DATA in the FS tree.

Key: (inode, EXTENT_DATA, file_offset). Describes how a range of file bytes maps to on-disk storage. Extents can be inline (data embedded in the item), regular (referencing a disk extent), or prealloc (reserved but unwritten).

Fields

generation: u64

Generation when this extent was allocated.

ram_bytes: u64

Uncompressed size of the data in this extent.

compression: CompressionType

Compression algorithm applied to the on-disk data.

extent_type: FileExtentType

Whether the extent is inline, regular, or preallocated.

body: FileExtentBody

Type-specific extent location.

Implementations

impl FileExtentItem

pub const HEADER_SIZE: usize = 21

Size of the fixed btrfs_file_extent_item header (the bytes before disk_bytenr / inline data).

pub const REGULAR_SIZE: usize = 53

Size of a regular or prealloc EXTENT_DATA item: 21-byte header plus 32-byte body (disk_bytenr, disk_num_bytes, offset, num_bytes).

pub fn parse(data: &[u8]) -> Option<Self>

Parse a file extent item from a raw byte buffer.

pub fn to_bytes_regular( generation: u64, ram_bytes: u64, compression: CompressionType, prealloc: bool, disk_bytenr: u64, disk_num_bytes: u64, offset: u64, num_bytes: u64, ) -> Vec<u8>

Serialize a regular or prealloc EXTENT_DATA item (53 bytes).

prealloc selects BTRFS_FILE_EXTENT_PREALLOC instead of the default BTRFS_FILE_EXTENT_REG. disk_bytenr of 0 represents a hole.

pub fn to_bytes_inline( generation: u64, ram_bytes: u64, compression: CompressionType, data: &[u8], ) -> Vec<u8>

Serialize an inline EXTENT_DATA item: 21-byte header followed by data bytes (raw or already-compressed/framed payload).

ram_bytes is the uncompressed file size covered by this inline extent. compression indicates whether data is compressed.

Trait Implementations

impl Clone for FileExtentItem

fn clone(&self) -> FileExtentItem

Returns a duplicate of the value.

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

Performs copy-assignment from source.

impl Debug for FileExtentItem

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

Formats the value using the given formatter.