Fix S/R support for fuse structs.

Add S/R support which was missing for a few structs in fuse, message queue and
tun packages.

PiperOrigin-RevId: 605139914

pkg/abi/linux/fuse.go

@@ -91,6 +91,7 @@ const (
 // FUSEHeaderIn is the header read by the daemon with each request.
 //
 // +marshal
+// +stateify savable
 type FUSEHeaderIn struct {
 	// Len specifies the total length of the data, including this header.
 	Len uint32
@@ -124,6 +125,7 @@ var SizeOfFUSEHeaderIn = uint32((*FUSEHeaderIn)(nil).SizeBytes())
 // reply; if they do not, this will be explicitly documented).
 //
 // +marshal
+// +stateify savable
 type FUSEHeaderOut struct {
 	// Len specifies the total length of the data, including this header.
 	Len uint32

pkg/sentry/fsimpl/fuse/BUILD

@@ -45,6 +45,7 @@ go_library(
         "regular_file.go",
         "request_list.go",
         "request_response.go",
+        "save_restore.go",
     ],
     marshal = True,
     visibility = ["//pkg/sentry:internal"],

pkg/sentry/fsimpl/fuse/directory.go

@@ -23,6 +23,7 @@ import (
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
+// +stateify savable
 type directoryFD struct {
 	fileDescription
 }

pkg/sentry/fsimpl/fuse/file.go

@@ -26,6 +26,8 @@ import (
 )
 
 // fileDescription implements vfs.FileDescriptionImpl for fuse.
+//
+// +stateify savable
 type fileDescription struct {
 	vfsfd vfs.FileDescription
 	vfs.FileDescriptionDefaultImpl

pkg/sentry/fsimpl/fuse/inode.go

@@ -75,7 +75,7 @@ type inode struct {
 	watches vfs.Watches
 
 	// attrMu protects the attributes of this inode.
-	attrMu sync.Mutex
+	attrMu sync.Mutex `state:"nosave"`
 
 	// +checklocks:attrMu
 	ino atomicbitops.Uint64 // Stat data, not accessed for path walking.

pkg/sentry/fsimpl/fuse/regular_file.go

@@ -30,11 +30,12 @@ import (
 	"gvisor.dev/gvisor/pkg/usermem"
 )
 
+// +stateify savable
 type regularFileFD struct {
 	fileDescription
 
 	// offMu protects off.
-	offMu sync.Mutex
+	offMu sync.Mutex `state:"nosave"`
 
 	// off is the file offset.
 	// +checklocks:offMu

pkg/sentry/fsimpl/fuse/request_response.go

@@ -137,7 +137,7 @@ func (conn *connection) NewRequest(creds *auth.Credentials, pid uint32, ino uint
 // +stateify savable
 type futureResponse struct {
 	opcode linux.FUSEOpcode
-	ch     chan struct{}
+	ch     chan struct{} `state:"nosave"`
 	hdr    *linux.FUSEHeaderOut
 	data   []byte
 

pkg/sentry/fsimpl/fuse/save_restore.go

@@ -0,0 +1,19 @@
+// Copyright 2024 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 fuse
+
+func (fRes *futureResponse) afterLoad() {
+	fRes.ch = make(chan struct{})
+}

pkg/sentry/kernel/mq/mq.go

@@ -308,6 +308,8 @@ type View interface {
 }
 
 // ReaderWriter provides a send and receive view into a queue.
+//
+// +stateify savable
 type ReaderWriter struct {
 	*Queue
 
@@ -315,6 +317,8 @@ type ReaderWriter struct {
 }
 
 // Reader provides a send-only view into a queue.
+//
+// +stateify savable
 type Reader struct {
 	*Queue
 
@@ -322,6 +326,8 @@ type Reader struct {
 }
 
 // Writer provides a receive-only view into a queue.
+//
+// +stateify savable
 type Writer struct {
 	*Queue
 

pkg/tcpip/link/tun/device.go

@@ -53,6 +53,8 @@ type Device struct {
 }
 
 // Flags set properties of a Device
+//
+// +stateify savable
 type Flags struct {
 	TUN          bool
 	TAP          bool

runsc/boot/restore.go

@@ -76,6 +76,9 @@ func (r *restorer) restore(l *Loader) error {
 		return fmt.Errorf("creating platform: %v", err)
 	}
 
+	// Start the old watchdog before replacing it with a new one below.
+	l.watchdog.Start()
+
 	// Release the kernel and replace it with a new one that will be restored into.
 	if l.k != nil {
 		l.k.Release()