btrfs_diskformat/extent/
block_group_item.rs

1use {
2    bitflags::bitflags,
3    byteorder::LE,
4    static_assertions::const_assert_eq,
5    zerocopy::{AsBytes, FromBytes, Unaligned, U64},
6};
7
8/// Defines the location, properties, and usage of a block group.
9#[derive(Copy, Clone, Debug, AsBytes, FromBytes, Unaligned)]
10#[repr(C, packed)]
11pub struct BlockGroupItem {
12    /// The space used, in bytes, in this block group.
13    pub used: U64<LE>,
14
15    /// The object ID of the chunk backing this block group.
16    pub chunk_objectid: U64<LE>,
17
18    /// Flags indicating allocation type and replication policy.
19    pub flags: U64<LE>,
20}
21const_assert_eq!(core::mem::size_of::<BlockGroupItem>(), 24);
22
23bitflags! {
24    /// The type of storage a block group allows.
25    ///
26    /// [Data] and [metadata] chunks may be mixed within a [block group], as indicated by its
27    /// [flags]. However, [system] chunks cannot be mixed.
28    ///
29    /// [Data]: AllocationType::DATA
30    /// [metadata]: AllocationType::METADATA
31    /// [block group]: BlockGroupItem
32    /// [flags]: BlockGroupItem::flags
33    /// [SYSTEM]: AllocationType::SYSTEM
34    pub struct AllocationType: u64 {
35        const DATA = 0x1;
36        const SYSTEM = 0x2;
37        const METADATA = 0x4;
38    }
39}
40
41bitflags! {
42    /// The replication policy a [block group] implements.
43    ///
44    /// Only one policy may be set for a given group.
45    ///
46    /// [block group]: BlockGroupItem
47    pub struct ReplicationPolicy: u64 {
48        const RAID0 = 0x8;
49        const RAID1 = 0x10;
50        const DUP = 0x20;
51        const RAID10 = 0x40;
52        const RAID5 = 0x80;
53        const RAID6 = 0x100;
54        const RAID1C3 = 0x200;
55        const RAID1C4 = 0x400;
56    }
57}
btrfs_diskformat/extent/block_group_item.rs

btrfs_diskformat/extent/
block_group_item.rs
