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// Copyright 2020 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 vfs
import (
"fmt"
"sync/atomic"
"gvisor.dev/gvisor/pkg/abi/linux"
"gvisor.dev/gvisor/pkg/context"
"gvisor.dev/gvisor/pkg/refsvfs2"
"gvisor.dev/gvisor/pkg/waiter"
)
// FilesystemImplSaveRestoreExtension is an optional extension to
// FilesystemImpl.
type FilesystemImplSaveRestoreExtension interface {
// PrepareSave prepares this filesystem for serialization.
PrepareSave(ctx context.Context) error
// CompleteRestore completes restoration from checkpoint for this
// filesystem after deserialization.
CompleteRestore(ctx context.Context, opts CompleteRestoreOptions) error
}
// PrepareSave prepares all filesystems for serialization.
func (vfs *VirtualFilesystem) PrepareSave(ctx context.Context) error {
failures := 0
for fs := range vfs.getFilesystems() {
if ext, ok := fs.impl.(FilesystemImplSaveRestoreExtension); ok {
if err := ext.PrepareSave(ctx); err != nil {
ctx.Warningf("%T.PrepareSave failed: %v", fs.impl, err)
failures++
}
}
fs.DecRef(ctx)
}
if failures != 0 {
return fmt.Errorf("%d filesystems failed to prepare for serialization", failures)
}
return nil
}
// CompleteRestore completes restoration from checkpoint for all filesystems
// after deserialization.
func (vfs *VirtualFilesystem) CompleteRestore(ctx context.Context, opts *CompleteRestoreOptions) error {
failures := 0
for fs := range vfs.getFilesystems() {
if ext, ok := fs.impl.(FilesystemImplSaveRestoreExtension); ok {
if err := ext.CompleteRestore(ctx, *opts); err != nil {
ctx.Warningf("%T.CompleteRestore failed: %v", fs.impl, err)
failures++
}
}
fs.DecRef(ctx)
}
if failures != 0 {
return fmt.Errorf("%d filesystems failed to complete restore after deserialization", failures)
}
return nil
}
// CompleteRestoreOptions contains options to
// VirtualFilesystem.CompleteRestore() and
// FilesystemImplSaveRestoreExtension.CompleteRestore().
type CompleteRestoreOptions struct {
// If ValidateFileSizes is true, filesystem implementations backed by
// remote filesystems should verify that file sizes have not changed
// between checkpoint and restore.
ValidateFileSizes bool
// If ValidateFileModificationTimestamps is true, filesystem
// implementations backed by remote filesystems should validate that file
// mtimes have not changed between checkpoint and restore.
ValidateFileModificationTimestamps bool
}
// saveMounts is called by stateify.
func (vfs *VirtualFilesystem) saveMounts() []*Mount {
if atomic.LoadPointer(&vfs.mounts.slots) == nil {
// vfs.Init() was never called.
return nil
}
var mounts []*Mount
vfs.mounts.Range(func(mount *Mount) bool {
mounts = append(mounts, mount)
return true
})
return mounts
}
// loadMounts is called by stateify.
func (vfs *VirtualFilesystem) loadMounts(mounts []*Mount) {
if mounts == nil {
return
}
vfs.mounts.Init()
for _, mount := range mounts {
vfs.mounts.Insert(mount)
}
}
func (mnt *Mount) afterLoad() {
if atomic.LoadInt64(&mnt.refs) != 0 {
refsvfs2.Register(mnt)
}
}
// afterLoad is called by stateify.
func (epi *epollInterest) afterLoad() {
// Mark all epollInterests as ready after restore so that the next call to
// EpollInstance.ReadEvents() rechecks their readiness.
epi.Callback(nil, waiter.EventMaskFromLinux(epi.mask))
}
// beforeSave is called by stateify.
func (fd *FileDescription) beforeSave() {
fd.saved = true
if fd.statusFlags&linux.O_ASYNC != 0 && fd.asyncHandler != nil {
fd.asyncHandler.Unregister(fd)
}
}
// afterLoad is called by stateify.
func (fd *FileDescription) afterLoad() {
if fd.statusFlags&linux.O_ASYNC != 0 && fd.asyncHandler != nil {
fd.asyncHandler.Register(fd)
}
}
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