Struct RootItem

#[repr(C, packed(1))]
pub struct RootItem {

    pub inode: InodeItem,
    pub generation: U64,
    pub root_dirid: U64,
    pub bytenr: U64,
    pub byte_limit: U64,
    pub bytes_used: U64,
    pub last_snapshot: U64,
    pub flags: U64,
    pub refs: U32,
    pub drop_progress: Key,
    pub drop_level: u8,
    pub level: u8,
    pub generation_v2: U64,
    pub uuid: UuidBytes,
    pub parent_uuid: UuidBytes,
    pub received_uuid: UuidBytes,
    pub ctransid: U64,
    pub otransid: U64,
    pub stransid: U64,
    pub rtransid: U64,
    pub ctime: Time,
    pub otime: Time,
    pub stime: Time,
    pub rtime: Time,
    pub _unused: [u64; 8],
}

Defines the location and parameters of the root of a b-tree.

Fields

inode: InodeItem

generation: U64

root_dirid: U64

bytenr: U64

byte_limit: U64

Currently unused. Always 0.

bytes_used: U64

Currently unused.

last_snapshot: U64

The transaction ID of the last transaction that created a snapshot of this root.

flags: U64

refs: U32

Only 0 or 1. Historically contained a reference count.

drop_progress: Key

Contains the key of the last dropped item during subvolume removal or relocation.

Value will be zeroed out otherwise.

drop_level: u8

The tree level of the node referenced in drop_progress.

level: u8

The height of this root’s tree.

generation_v2: U64

Value to help determine whether this root has been modified by an older btrfs implementation.

If the value is equal to generation, the fields below are valid. Otherwise, this indicates the fields are invalid but recoverable.

uuid: UuidBytes

The subvolume’s UUID.

parent_uuid: UuidBytes

The parent’s subvolume UUID.

This is used during send/receive.

received_uuid: UuidBytes

The received UUID.

This is used during send/receive.

ctransid: U64

The transaction ID of the last transaction that modified the tree.

Note: some operations like internal caches or relocation will not update this value.

otransid: U64

The transaction ID of the transaction that created the tree.

stransid: U64

The transaction ID for the transaction that sent this subvolume.

This value is non-zero for a received subvolume.

rtransid: U64

The transaction ID for the transaction that received this subvolume.

This value is non-zero for a received subvolume.

ctime: Time

The timestamp of the ctransid.

otime: Time

The timestamp of the otransid.

stime: Time

The timestamp of the stransid.

rtime: Time

The timestamp of the rtransid.

_unused: [u64; 8]

Currently unused. Reserved for future use.

Trait Implementations

impl Clone for RootItem

fn clone(&self) -> RootItem

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Debug for RootItem

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

Formats the value using the given formatter.

impl FromBytes for RootItem

where InodeItem: FromBytes, U64: FromBytes, U32: FromBytes, Key: FromBytes, u8: FromBytes, UuidBytes: FromBytes, Time: FromBytes, [u64; 8]: FromBytes,

fn mut_from_bytes( source: &mut [u8], ) -> Result<&mut Self, ConvertError<AlignmentError<&mut [u8], Self>, SizeError<&mut [u8], Self>, Infallible>>

where Self: IntoBytes + KnownLayout,

Interprets the given source as a &mut Self.

fn mut_from_prefix( source: &mut [u8], ) -> Result<(&mut Self, &mut [u8]), ConvertError<AlignmentError<&mut [u8], Self>, SizeError<&mut [u8], Self>, Infallible>>

where Self: IntoBytes + KnownLayout,

Interprets the prefix of the given source as a &mut Self without copying.

fn mut_from_suffix( source: &mut [u8], ) -> Result<(&mut [u8], &mut Self), ConvertError<AlignmentError<&mut [u8], Self>, SizeError<&mut [u8], Self>, Infallible>>

where Self: IntoBytes + KnownLayout,

Interprets the suffix of the given source as a &mut Self without copying.

fn mut_from_prefix_with_elems( source: &mut [u8], count: usize, ) -> Result<(&mut Self, &mut [u8]), ConvertError<AlignmentError<&mut [u8], Self>, SizeError<&mut [u8], Self>, Infallible>>

where Self: IntoBytes + KnownLayout<PointerMetadata = usize>,

Interprets the prefix of the given source as a &mut Self with DST length equal to count.

fn mut_from_suffix_with_elems( source: &mut [u8], count: usize, ) -> Result<(&mut [u8], &mut Self), ConvertError<AlignmentError<&mut [u8], Self>, SizeError<&mut [u8], Self>, Infallible>>

where Self: IntoBytes + KnownLayout<PointerMetadata = usize>,

Interprets the suffix of the given source as a &mut Self with DST length equal to count.

fn read_from_bytes(source: &[u8]) -> Result<Self, SizeError<&[u8], Self>>

where Self: Sized,

Reads a copy of Self from the given source.

fn read_from_prefix( source: &[u8], ) -> Result<(Self, &[u8]), SizeError<&[u8], Self>>

where Self: Sized,

Reads a copy of Self from the prefix of the given source.

fn read_from_suffix( source: &[u8], ) -> Result<(&[u8], Self), SizeError<&[u8], Self>>

where Self: Sized,

Reads a copy of Self from the suffix of the given source.

impl FromZeros for RootItem

where InodeItem: FromZeros, U64: FromZeros, U32: FromZeros, Key: FromZeros, u8: FromZeros, UuidBytes: FromZeros, Time: FromZeros, [u64; 8]: FromZeros,

fn zero(&mut self)

Overwrites self with zeros.

fn new_zeroed() -> Self

where Self: Sized,

Creates an instance of Self from zeroed bytes.

impl IntoBytes for RootItem

where InodeItem: IntoBytes, U64: IntoBytes, U32: IntoBytes, Key: IntoBytes, u8: IntoBytes, UuidBytes: IntoBytes, Time: IntoBytes, [u64; 8]: IntoBytes,

fn as_mut_bytes(&mut self) -> &mut [u8]

where Self: FromBytes,

Gets the bytes of this value mutably.

impl KnownLayout for RootItem

where [u64; 8]: KnownLayout,

type PointerMetadata = <[u64; 8] as KnownLayout>::PointerMetadata

The type of metadata stored in a pointer to Self.

impl TryFromBytes for RootItem

where InodeItem: TryFromBytes, U64: TryFromBytes, U32: TryFromBytes, Key: TryFromBytes, u8: TryFromBytes, UuidBytes: TryFromBytes, Time: TryFromBytes, [u64; 8]: TryFromBytes,

fn try_mut_from_bytes( bytes: &mut [u8], ) -> Result<&mut Self, ConvertError<AlignmentError<&mut [u8], Self>, SizeError<&mut [u8], Self>, ValidityError<&mut [u8], Self>>>

where Self: KnownLayout + IntoBytes,

Attempts to interpret the given source as a &mut Self without copying.

fn try_mut_from_prefix( source: &mut [u8], ) -> Result<(&mut Self, &mut [u8]), ConvertError<AlignmentError<&mut [u8], Self>, SizeError<&mut [u8], Self>, ValidityError<&mut [u8], Self>>>

where Self: KnownLayout + IntoBytes,

Attempts to interpret the prefix of the given source as a &mut Self.

fn try_mut_from_suffix( source: &mut [u8], ) -> Result<(&mut [u8], &mut Self), ConvertError<AlignmentError<&mut [u8], Self>, SizeError<&mut [u8], Self>, ValidityError<&mut [u8], Self>>>

where Self: KnownLayout + IntoBytes,

Attempts to interpret the suffix of the given source as a &mut Self.

fn try_mut_from_bytes_with_elems( source: &mut [u8], count: usize, ) -> Result<&mut Self, ConvertError<AlignmentError<&mut [u8], Self>, SizeError<&mut [u8], Self>, ValidityError<&mut [u8], Self>>>

where Self: KnownLayout<PointerMetadata = usize> + IntoBytes,

Attempts to interpret the given source as a &mut Self with a DST length equal to count.

fn try_mut_from_prefix_with_elems( source: &mut [u8], count: usize, ) -> Result<(&mut Self, &mut [u8]), ConvertError<AlignmentError<&mut [u8], Self>, SizeError<&mut [u8], Self>, ValidityError<&mut [u8], Self>>>

where Self: KnownLayout<PointerMetadata = usize> + IntoBytes,

Attempts to interpret the prefix of the given source as a &mut Self with a DST length equal to count.

fn try_mut_from_suffix_with_elems( source: &mut [u8], count: usize, ) -> Result<(&mut [u8], &mut Self), ConvertError<AlignmentError<&mut [u8], Self>, SizeError<&mut [u8], Self>, ValidityError<&mut [u8], Self>>>

where Self: KnownLayout<PointerMetadata = usize> + IntoBytes,

Attempts to interpret the suffix of the given source as a &mut Self with a DST length equal to count.

fn try_read_from_bytes( source: &[u8], ) -> Result<Self, ConvertError<Infallible, SizeError<&[u8], Self>, ValidityError<&[u8], Self>>>

where Self: Sized,

Attempts to read the given source as a Self.

fn try_read_from_prefix( source: &[u8], ) -> Result<(Self, &[u8]), ConvertError<Infallible, SizeError<&[u8], Self>, ValidityError<&[u8], Self>>>

where Self: Sized,

Attempts to read a Self from the prefix of the given source.

fn try_read_from_suffix( source: &[u8], ) -> Result<(&[u8], Self), ConvertError<Infallible, SizeError<&[u8], Self>, ValidityError<&[u8], Self>>>

where Self: Sized,

Attempts to read a Self from the suffix of the given source.

impl Copy for RootItem

impl Unaligned for RootItem