Struct btrfs_diskformat::RootItem

#[repr(C, packed)]pub struct RootItem {
    pub inode: InodeItem,
    pub generation: U64<LE>,
    pub root_dirid: U64<LE>,
    pub bytenr: U64<LE>,
    pub byte_limit: U64<LE>,
    pub bytes_used: U64<LE>,
    pub last_snapshot: U64<LE>,
    pub flags: U64<LE>,
    pub refs: U32<LE>,
    pub drop_progress: Key,
    pub drop_level: u8,
    pub level: u8,
    pub generation_v2: U64<LE>,
    pub uuid: UuidBytes,
    pub parent_uuid: UuidBytes,
    pub received_uuid: UuidBytes,
    pub ctransid: U64<LE>,
    pub otransid: U64<LE>,
    pub stransid: U64<LE>,
    pub rtransid: U64<LE>,
    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<LE>

root_dirid: U64<LE>

bytenr: U64<LE>

byte_limit: U64<LE>

Currently unused. Always 0.

bytes_used: U64<LE>

Currently unused.

last_snapshot: U64<LE>

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

flags: U64<LE>

refs: U32<LE>

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<LE>

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<LE>

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<LE>

The transaction ID of the transaction that created the tree.

stransid: U64<LE>

The transaction ID for the transaction that sent this subvolume.

This value is non-zero for a received subvolume.

rtransid: U64<LE>

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 AsBytes for RootItem

fn only_derive_is_allowed_to_implement_this_trait() where
    Self: Sized, 

pub fn as_bytes(&self) -> &[u8]

Get the bytes of this value.

pub fn as_bytes_mut(&mut self) -> &mut [u8] where
    Self: FromBytes, 

Get the bytes of this value mutably.

impl Clone for RootItem

fn clone(&self) -> RootItem

Returns a copy of the value.

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

Performs copy-assignment from source.

impl Copy for RootItem

impl Debug for RootItem

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

Formats the value using the given formatter.

impl FromBytes for RootItem

fn only_derive_is_allowed_to_implement_this_trait() where
    Self: Sized, 

impl Unaligned for RootItem

fn only_derive_is_allowed_to_implement_this_trait() where
    Self: Sized,