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// Copyright (C) 2022-2023 Luke Shumaker <lukeshu@lukeshu.com>
//
// SPDX-License-Identifier: GPL-2.0-or-later
package btrfsvol
import (
"fmt"
"git.lukeshu.com/btrfs-progs-ng/lib/containers"
"git.lukeshu.com/btrfs-progs-ng/lib/slices"
)
// physical => logical
type devextMapping struct {
PAddr PhysicalAddr
LAddr LogicalAddr
Size AddrDelta
SizeLocked bool
Flags containers.Optional[BlockGroupFlags]
}
// Compare implements containers.Ordered.
func (a devextMapping) Compare(b devextMapping) int {
return containers.NativeCompare(a.PAddr, b.PAddr)
}
// return -1 if 'a' is wholly to the left of 'b'
// return 0 if there is some overlap between 'a' and 'b'
// return 1 if 'a is wholly to the right of 'b'
func (a devextMapping) compareRange(b devextMapping) int {
switch {
case a.PAddr.Add(a.Size) <= b.PAddr:
// 'a' is wholly to the left of 'b'.
return -1
case b.PAddr.Add(b.Size) <= a.PAddr:
// 'a' is wholly to the right of 'b'.
return 1
default:
// There is some overlap.
return 0
}
}
func (a devextMapping) union(rest ...devextMapping) (devextMapping, error) {
// sanity check
for _, ext := range rest {
if a.compareRange(ext) != 0 {
return devextMapping{}, fmt.Errorf("devexts don't overlap")
}
}
exts := append([]devextMapping{a}, rest...)
// figure out the physical range (.PAddr and .Size)
beg := exts[0].PAddr
end := beg.Add(exts[0].Size)
for _, ext := range exts {
beg = slices.Min(beg, ext.PAddr)
end = slices.Max(end, ext.PAddr.Add(ext.Size))
}
ret := devextMapping{
PAddr: beg,
Size: end.Sub(beg),
}
for _, ext := range exts {
if ext.SizeLocked {
ret.SizeLocked = true
if ret.Size != ext.Size {
return devextMapping{}, fmt.Errorf("member devext has locked size=%v, but union would have size=%v",
ext.Size, ret.Size)
}
}
}
// figure out the logical range (.LAddr)
first := true
for _, ext := range exts {
offsetWithinRet := ext.PAddr.Sub(ret.PAddr)
laddr := ext.LAddr.Add(-offsetWithinRet)
if first {
ret.LAddr = laddr
} else if laddr != ret.LAddr {
return ret, fmt.Errorf("devexts don't agree on laddr: %v != %v", ret.LAddr, laddr)
}
}
// figure out the flags (.Flags)
for _, ext := range exts {
if !ext.Flags.OK {
continue
}
if !ret.Flags.OK {
ret.Flags = ext.Flags
}
if ret.Flags != ext.Flags {
return ret, fmt.Errorf("mismatch flags: %v != %v", ret.Flags.Val, ext.Flags.Val)
}
}
// done
return ret, nil
}
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