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package btrfsvol
import (
"fmt"
"lukeshu.com/btrfs-tools/pkg/util"
)
// physical => logical
type devextMapping struct {
PAddr PhysicalAddr
LAddr LogicalAddr
Size AddrDelta
Flags *BlockGroupFlags
}
// 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) cmpRange(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.cmpRange(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 = util.Min(beg, ext.PAddr)
end = util.Max(end, ext.PAddr.Add(ext.Size))
}
ret := devextMapping{
PAddr: beg,
Size: end.Sub(beg),
}
// 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 == nil {
continue
}
if ret.Flags == nil {
val := *ext.Flags
ret.Flags = &val
}
if *ret.Flags != *ext.Flags {
return ret, fmt.Errorf("mismatch flags: %v != %v", *ret.Flags, *ext.Flags)
}
}
// done
return ret, nil
}
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