github.com/metacubex/gvisor@v0.0.0-20240320004321-933faba989ec/pkg/sentry/fsimpl/tmpfs/save_restore.go (about)

     1  // Copyright 2020 The gVisor Authors.
     2  //
     3  // Licensed under the Apache License, Version 2.0 (the "License");
     4  // you may not use this file except in compliance with the License.
     5  // You may obtain a copy of the License at
     6  //
     7  //     http://www.apache.org/licenses/LICENSE-2.0
     8  //
     9  // Unless required by applicable law or agreed to in writing, software
    10  // distributed under the License is distributed on an "AS IS" BASIS,
    11  // WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
    12  // See the License for the specific language governing permissions and
    13  // limitations under the License.
    14  
    15  package tmpfs
    16  
    17  import (
    18  	goContext "context"
    19  	"fmt"
    20  
    21  	"github.com/metacubex/gvisor/pkg/context"
    22  	"github.com/metacubex/gvisor/pkg/sentry/pgalloc"
    23  	"github.com/metacubex/gvisor/pkg/sentry/vfs"
    24  )
    25  
    26  // saveMf is called by stateify.
    27  func (fs *filesystem) saveMf() string {
    28  	if !fs.mf.IsSavable() {
    29  		panic(fmt.Sprintf("Can't save tmpfs filesystem because its MemoryFile is not savable: %v", fs.mf))
    30  	}
    31  	return fs.mf.RestoreID()
    32  }
    33  
    34  // loadMf is called by stateify.
    35  func (fs *filesystem) loadMf(ctx goContext.Context, restoreID string) {
    36  	if restoreID == "" {
    37  		fs.mf = pgalloc.MemoryFileFromContext(ctx)
    38  		return
    39  	}
    40  	mfmap := pgalloc.MemoryFileMapFromContext(ctx)
    41  	if mfmap == nil {
    42  		panic("CtxMemoryFileMap was not provided")
    43  	}
    44  	mf, ok := mfmap[restoreID]
    45  	if !ok {
    46  		panic(fmt.Sprintf("Memory file for %q not found in CtxMemoryFileMap", restoreID))
    47  	}
    48  	fs.mf = mf
    49  }
    50  
    51  // saveParent is called by stateify.
    52  func (d *dentry) saveParent() *dentry {
    53  	return d.parent.Load()
    54  }
    55  
    56  // loadParent is called by stateify.
    57  func (d *dentry) loadParent(_ goContext.Context, parent *dentry) {
    58  	d.parent.Store(parent)
    59  }
    60  
    61  // PrepareSave implements vfs.FilesystemImplSaveRestoreExtension.PrepareSave.
    62  func (fs *filesystem) PrepareSave(ctx context.Context) error {
    63  	restoreID := fs.mf.RestoreID()
    64  	if restoreID == "" {
    65  		return nil
    66  	}
    67  	mfmap := pgalloc.MemoryFileMapFromContext(ctx)
    68  	if mfmap == nil {
    69  		return fmt.Errorf("CtxMemoryFileMap was not provided")
    70  	}
    71  	if _, ok := mfmap[restoreID]; ok {
    72  		return fmt.Errorf("memory file for %q already exists in CtxMemoryFileMap", restoreID)
    73  	}
    74  	mfmap[restoreID] = fs.mf
    75  	return nil
    76  }
    77  
    78  // CompleteRestore implements
    79  // vfs.FilesystemImplSaveRestoreExtension.CompleteRestore.
    80  func (fs *filesystem) CompleteRestore(ctx context.Context, opts vfs.CompleteRestoreOptions) error {
    81  	return nil
    82  }