btrfs_diskformat/extent/
block_group_item.rs

1use bitflags::bitflags;
2use static_assertions::const_assert_eq;
3use zerocopy::little_endian::U64 as U64LE;
4use zerocopy_derive::*;
5
6/// Defines the location, properties, and usage of a block group.
7#[derive(Copy, Clone, Debug, Hash, IntoBytes, FromBytes, Unaligned, KnownLayout, Immutable)]
8#[repr(C, packed)]
9pub struct BlockGroupItem {
10    /// The space used, in bytes, in this block group.
11    pub used: U64LE,
12
13    /// The object ID of the chunk backing this block group.
14    pub chunk_objectid: U64LE,
15
16    /// Flags indicating allocation type and replication policy.
17    pub flags: U64LE,
18}
19const_assert_eq!(core::mem::size_of::<BlockGroupItem>(), 24);
20
21bitflags! {
22    /// The type of storage a block group allows.
23    ///
24    /// [Data] and [metadata] chunks may be mixed within a [block group], as indicated by its
25    /// [flags]. However, [system] chunks cannot be mixed.
26    ///
27    /// [Data]: AllocationType::DATA
28    /// [metadata]: AllocationType::METADATA
29    /// [block group]: BlockGroupItem
30    /// [flags]: BlockGroupItem::flags
31    /// [SYSTEM]: AllocationType::SYSTEM
32    pub struct AllocationType: u64 {
33        const DATA = 0x1;
34        const SYSTEM = 0x2;
35        const METADATA = 0x4;
36    }
37}
38
39bitflags! {
40    /// The replication policy a [block group] implements.
41    ///
42    /// Only one policy may be set for a given group.
43    ///
44    /// [block group]: BlockGroupItem
45    pub struct ReplicationPolicy: u64 {
46        const RAID0 = 0x8;
47        const RAID1 = 0x10;
48        const DUP = 0x20;
49        const RAID10 = 0x40;
50        const RAID5 = 0x80;
51        const RAID6 = 0x100;
52        const RAID1C3 = 0x200;
53        const RAID1C4 = 0x400;
54    }
55}
btrfs_diskformat/extent/block_group_item.rs

btrfs_diskformat/extent/
block_group_item.rs
