96 lines
3.0 KiB
Go
96 lines
3.0 KiB
Go
|
// Copyright 2018 Google Inc.
|
||
|
|
//
|
||
|
|
// 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 fs
|
||
|
|
|
||
|
|
import "gvisor.googlesource.com/gvisor/pkg/sentry/context"
|
||
|
|
|
||
|
|
// overlayMountSourceOperations implements MountSourceOperations for an overlay
|
||
|
|
// mount point.
|
||
|
|
type overlayMountSourceOperations struct {
|
||
|
|
upper *MountSource
|
||
|
|
lower *MountSource
|
||
|
|
}
|
||
|
|
|
||
|
|
func newOverlayMountSource(upper, lower *MountSource, flags MountSourceFlags) *MountSource {
|
||
|
|
upper.IncRef()
|
||
|
|
lower.IncRef()
|
||
|
|
return NewMountSource(&overlayMountSourceOperations{
|
||
|
|
upper: upper,
|
||
|
|
lower: lower,
|
||
|
|
}, &overlayFilesystem{}, flags)
|
||
|
|
}
|
||
|
|
|
||
|
|
// Revalidate panics if the upper or lower MountSource require that dirent be
|
||
|
|
// revalidated. Otherwise always returns false.
|
||
|
|
func (o *overlayMountSourceOperations) Revalidate(dirent *Dirent) bool {
|
||
|
|
if o.upper.Revalidate(dirent) || o.lower.Revalidate(dirent) {
|
||
|
|
panic("an overlay cannot revalidate file objects")
|
||
|
|
}
|
||
|
|
return false
|
||
|
|
}
|
||
|
|
|
||
|
|
// Keep returns true if either upper or lower MountSource require that the
|
||
|
|
// dirent be kept in memory.
|
||
|
|
func (o *overlayMountSourceOperations) Keep(dirent *Dirent) bool {
|
||
|
|
return o.upper.Keep(dirent) || o.lower.Keep(dirent)
|
||
|
|
}
|
||
|
|
|
||
|
|
// ResetInodeMappings propagates the call to both upper and lower MountSource.
|
||
|
|
func (o *overlayMountSourceOperations) ResetInodeMappings() {
|
||
|
|
o.upper.ResetInodeMappings()
|
||
|
|
o.lower.ResetInodeMappings()
|
||
|
|
}
|
||
|
|
|
||
|
|
// SaveInodeMapping propagates the call to both upper and lower MountSource.
|
||
|
|
func (o *overlayMountSourceOperations) SaveInodeMapping(inode *Inode, path string) {
|
||
|
|
inode.overlay.copyMu.RLock()
|
||
|
|
defer inode.overlay.copyMu.RUnlock()
|
||
|
|
if inode.overlay.upper != nil {
|
||
|
|
o.upper.SaveInodeMapping(inode.overlay.upper, path)
|
||
|
|
}
|
||
|
|
if inode.overlay.lower != nil {
|
||
|
|
o.lower.SaveInodeMapping(inode.overlay.lower, path)
|
||
|
|
}
|
||
|
|
}
|
||
|
|
|
||
|
|
// Destroy drops references on the upper and lower MountSource.
|
||
|
|
func (o *overlayMountSourceOperations) Destroy() {
|
||
|
|
o.upper.DecRef()
|
||
|
|
o.lower.DecRef()
|
||
|
|
}
|
||
|
|
|
||
|
|
// type overlayFilesystem is the filesystem for overlay mounts.
|
||
|
|
type overlayFilesystem struct{}
|
||
|
|
|
||
|
|
// Name implements Filesystem.Name.
|
||
|
|
func (ofs *overlayFilesystem) Name() string {
|
||
|
|
return "overlayfs"
|
||
|
|
}
|
||
|
|
|
||
|
|
// Flags implements Filesystem.Flags.
|
||
|
|
func (ofs *overlayFilesystem) Flags() FilesystemFlags {
|
||
|
|
return 0
|
||
|
|
}
|
||
|
|
|
||
|
|
// AllowUserMount implements Filesystem.AllowUserMount.
|
||
|
|
func (ofs *overlayFilesystem) AllowUserMount() bool {
|
||
|
|
return false
|
||
|
|
}
|
||
|
|
|
||
|
|
// Mount implements Filesystem.Mount.
|
||
|
|
func (ofs *overlayFilesystem) Mount(ctx context.Context, device string, flags MountSourceFlags, data string) (*Inode, error) {
|
||
|
|
panic("overlayFilesystem.Mount should not be called!")
|
||
|
|
}
|