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// Copyright 2018 The gVisor Authors.
//
// Licensed under the Apache License, Version 2.0 (the "License");
// you may not use this file except in compliance with the License.
// You may obtain a copy of the License at
//
// http://www.apache.org/licenses/LICENSE-2.0
//
// Unless required by applicable law or agreed to in writing, software
// distributed under the License is distributed on an "AS IS" BASIS,
// WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
// See the License for the specific language governing permissions and
// limitations under the License.
package fsutil
import (
"math"
"gvisor.dev/gvisor/pkg/sentry/memmap"
"gvisor.dev/gvisor/pkg/sentry/usage"
)
// FrameRefSegInfo holds reference count and memory cgroup id of the segment.
type FrameRefSegInfo struct {
// refs indicates the reference count of the segment.
refs uint64
// memCgID is the memory cgroup id of the first task which touches the
// segment. This will not be changed over the lifetime of the segment.
memCgID uint32
}
// FrameRefSetFunctions implements segment.Functions for FrameRefSet.
type FrameRefSetFunctions struct{}
// MinKey implements segment.Functions.MinKey.
func (FrameRefSetFunctions) MinKey() uint64 {
return 0
}
// MaxKey implements segment.Functions.MaxKey.
func (FrameRefSetFunctions) MaxKey() uint64 {
return math.MaxUint64
}
// ClearValue implements segment.Functions.ClearValue.
func (FrameRefSetFunctions) ClearValue(val *FrameRefSegInfo) {
}
// Merge implements segment.Functions.Merge.
func (FrameRefSetFunctions) Merge(_ memmap.FileRange, val1 FrameRefSegInfo, _ memmap.FileRange, val2 FrameRefSegInfo) (FrameRefSegInfo, bool) {
if val1 != val2 {
return FrameRefSegInfo{}, false
}
return val1, true
}
// Split implements segment.Functions.Split.
func (FrameRefSetFunctions) Split(_ memmap.FileRange, val FrameRefSegInfo, _ uint64) (FrameRefSegInfo, FrameRefSegInfo) {
return val, val
}
// IncRefAndAccount adds a reference on the range fr. All newly inserted segments
// are accounted as host page cache memory mappings. The new segments will be
// associated with the memCgID, if the segment already exists then the memCgID
// will not be changed.
func (s *FrameRefSet) IncRefAndAccount(fr memmap.FileRange, memCgID uint32) {
seg, gap := s.Find(fr.Start)
for {
switch {
case seg.Ok() && seg.Start() < fr.End:
seg = s.Isolate(seg, fr)
seg.ValuePtr().refs++
seg, gap = seg.NextNonEmpty()
case gap.Ok() && gap.Start() < fr.End:
newRange := gap.Range().Intersect(fr)
usage.MemoryAccounting.Inc(newRange.Length(), usage.Mapped, memCgID)
frInfo := FrameRefSegInfo{refs: 1, memCgID: memCgID}
seg, gap = s.InsertWithoutMerging(gap, newRange, frInfo).NextNonEmpty()
default:
s.MergeOutsideRange(fr)
return
}
}
}
// DecRefAndAccount removes a reference on the range fr and untracks segments
// that are removed from memory accounting.
func (s *FrameRefSet) DecRefAndAccount(fr memmap.FileRange) {
seg := s.FindSegment(fr.Start)
for seg.Ok() && seg.Start() < fr.End {
seg = s.Isolate(seg, fr)
if old := seg.ValuePtr().refs; old == 1 {
usage.MemoryAccounting.Dec(seg.Range().Length(), usage.Mapped, seg.ValuePtr().memCgID)
seg = s.Remove(seg).NextSegment()
} else {
seg.ValuePtr().refs--
seg = seg.NextSegment()
}
}
s.MergeOutsideRange(fr)
}
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