github.com/SagerNet/gvisor@v0.0.0-20210707092255-7731c139d75c/pkg/sentry/fsimpl/ext/dentry.go (about)

     1  // Copyright 2019 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 ext
    16  
    17  import (
    18  	"github.com/SagerNet/gvisor/pkg/context"
    19  	"github.com/SagerNet/gvisor/pkg/sentry/vfs"
    20  )
    21  
    22  // dentry implements vfs.DentryImpl.
    23  //
    24  // +stateify savable
    25  type dentry struct {
    26  	vfsd vfs.Dentry
    27  
    28  	// Protected by filesystem.mu.
    29  	parent *dentry
    30  	name   string
    31  
    32  	// inode is the inode represented by this dentry. Multiple Dentries may
    33  	// share a single non-directory Inode (with hard links). inode is
    34  	// immutable.
    35  	inode *inode
    36  }
    37  
    38  // Compiles only if dentry implements vfs.DentryImpl.
    39  var _ vfs.DentryImpl = (*dentry)(nil)
    40  
    41  // newDentry is the dentry constructor.
    42  func newDentry(in *inode) *dentry {
    43  	d := &dentry{
    44  		inode: in,
    45  	}
    46  	d.vfsd.Init(d)
    47  	return d
    48  }
    49  
    50  // IncRef implements vfs.DentryImpl.IncRef.
    51  func (d *dentry) IncRef() {
    52  	d.inode.incRef()
    53  }
    54  
    55  // TryIncRef implements vfs.DentryImpl.TryIncRef.
    56  func (d *dentry) TryIncRef() bool {
    57  	return d.inode.tryIncRef()
    58  }
    59  
    60  // DecRef implements vfs.DentryImpl.DecRef.
    61  func (d *dentry) DecRef(ctx context.Context) {
    62  	// FIXME(b/134676337): filesystem.mu may not be locked as required by
    63  	// inode.decRef().
    64  	d.inode.decRef()
    65  }
    66  
    67  // InotifyWithParent implements vfs.DentryImpl.InotifyWithParent.
    68  //
    69  // TODO(b/134676337): Implement inotify.
    70  func (d *dentry) InotifyWithParent(ctx context.Context, events, cookie uint32, et vfs.EventType) {}
    71  
    72  // Watches implements vfs.DentryImpl.Watches.
    73  //
    74  // TODO(b/134676337): Implement inotify.
    75  func (d *dentry) Watches() *vfs.Watches {
    76  	return nil
    77  }
    78  
    79  // OnZeroWatches implements vfs.Dentry.OnZeroWatches.
    80  //
    81  // TODO(b/134676337): Implement inotify.
    82  func (d *dentry) OnZeroWatches(context.Context) {}