1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
|
// Copyright (C) 2022-2023 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package btrfsitem
import (
"git.lukeshu.com/btrfs-progs-ng/lib/binstruct"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsprim"
"git.lukeshu.com/btrfs-progs-ng/lib/btrfs/btrfsvol"
)
// A DevExtent tracks allocation of the physical address space.
//
// Compare with:
// - BlockGroups, which track allocation of the logical address space.
// - Chunks, which map logical addresses to physical addresses.
//
// The relationship between the three is
//
// DevExtent---[many:one]---Chunk---[one:one]---BlockGroup
//
// The device ID identifies which Dev item describes the physical
// volume that the DevExtent is on.
//
// Key:
//
// key.objectid = device_id
// key.offset = physical_addr
type DevExtent struct { // trivial DEV_EXTENT=204
ChunkTree btrfsprim.ObjID `bin:"off=0, siz=8"` // always CHUNK_TREE_OBJECTID
ChunkObjectID btrfsprim.ObjID `bin:"off=8, siz=8"` // which chunk within .ChunkTree owns this extent, always FIRST_CHUNK_TREE_OBJECTID
ChunkOffset btrfsvol.LogicalAddr `bin:"off=16, siz=8"` // offset of the CHUNK_ITEM that owns this extent, within the .ChunkObjectID
Length btrfsvol.AddrDelta `bin:"off=24, siz=8"`
ChunkTreeUUID btrfsprim.UUID `bin:"off=32, siz=16"`
binstruct.End `bin:"off=48"`
}
func (devext DevExtent) Mapping(key btrfsprim.Key) btrfsvol.Mapping {
return btrfsvol.Mapping{
LAddr: devext.ChunkOffset,
PAddr: btrfsvol.QualifiedPhysicalAddr{
Dev: btrfsvol.DeviceID(key.ObjectID),
Addr: btrfsvol.PhysicalAddr(key.Offset),
},
Size: devext.Length,
SizeLocked: true,
}
}
|