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// 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"
"git.lukeshu.com/btrfs-progs-ng/lib/fmtutil"
)
// A Root goes in the ROOT_TREE and defines one of the other trees in
// the filesystem. All trees have a Root item describing them, except
// for the ROOT_TREE, CHUNK_TREE, TREE_LOG, and BLOCK_GROUP_TREE,
// which are defined directly in the superblock.
//
// Key:
//
// key.objectid = tree ID
// key.offset = one of:
// - 0 if objectid is one of the BTRFS_*_TREE_OBJECTID defines or a non-snapshot volume; or
// - transaction_id of when this snapshot was created
//
// This tree might contain nodes with node.Head.Owner set to the
// root.ParentUUID tree, *if* the node.Head.Generation is
// less-than-or-equal-to the root's key.offset. The "or-equal-to"
// part of that might be surprising, which is why I called it out.
type Root struct { // trivial ROOT_ITEM=132
Inode Inode `bin:"off=0x000, siz=0xa0"` // ???
Generation btrfsprim.Generation `bin:"off=0x0a0, siz=0x08"`
RootDirID btrfsprim.ObjID `bin:"off=0x0a8, siz=0x08"` // inode number of the root inode
ByteNr btrfsvol.LogicalAddr `bin:"off=0x0b0, siz=0x08"` // root node
ByteLimit int64 `bin:"off=0x0b8, siz=0x08"` // always 0 (unused)
BytesUsed int64 `bin:"off=0x0c0, siz=0x08"`
LastSnapshot int64 `bin:"off=0x0c8, siz=0x08"`
Flags RootFlags `bin:"off=0x0d0, siz=0x08"`
Refs int32 `bin:"off=0x0d8, siz=0x04"`
DropProgress btrfsprim.Key `bin:"off=0x0dc, siz=0x11"`
DropLevel uint8 `bin:"off=0x0ed, siz=0x01"`
Level uint8 `bin:"off=0x0ee, siz=0x01"`
GenerationV2 btrfsprim.Generation `bin:"off=0x0ef, siz=0x08"`
UUID btrfsprim.UUID `bin:"off=0x0f7, siz=0x10"`
ParentUUID btrfsprim.UUID `bin:"off=0x107, siz=0x10"`
ReceivedUUID btrfsprim.UUID `bin:"off=0x117, siz=0x10"`
CTransID int64 `bin:"off=0x127, siz=0x08"`
OTransID int64 `bin:"off=0x12f, siz=0x08"`
STransID int64 `bin:"off=0x137, siz=0x08"`
RTransID int64 `bin:"off=0x13f, siz=0x08"`
CTime btrfsprim.Time `bin:"off=0x147, siz=0x0c"`
OTime btrfsprim.Time `bin:"off=0x153, siz=0x0c"`
STime btrfsprim.Time `bin:"off=0x15f, siz=0x0c"`
RTime btrfsprim.Time `bin:"off=0x16b, siz=0x0c"`
GlobalTreeID btrfsprim.ObjID `bin:"off=0x177, siz=0x08"` // ???
Reserved [7]int64 `bin:"off=0x17f, siz=0x38"`
binstruct.End `bin:"off=0x1b7"`
}
type RootFlags uint64
const (
ROOT_SUBVOL_RDONLY RootFlags = 1 << iota
)
var rootFlagNames = []string{
"SUBVOL_RDONLY",
}
func (f RootFlags) Has(req RootFlags) bool { return f&req == req }
func (f RootFlags) String() string { return fmtutil.BitfieldString(f, rootFlagNames, fmtutil.HexLower) }
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