Merge release-20200323.0-203-g9b5e305 (automated)

21 files changed, 758 insertions, 714 deletions

diff --git a/pkg/sentry/fsimpl/gofer/directory.go b/pkg/sentry/fsimpl/gofer/directory.go
index 49d9f859b..d02691232 100755
--- a/pkg/sentry/fsimpl/gofer/directory.go
+++ b/pkg/sentry/fsimpl/gofer/directory.go
@@ -29,13 +29,25 @@ func (d *dentry) isDir() bool {
 	return d.fileType() == linux.S_IFDIR
 }
 
+// Preconditions: filesystem.renameMu must be locked. d.dirMu must be locked.
+// d.isDir(). child must be a newly-created dentry that has never had a parent.
+func (d *dentry) cacheNewChildLocked(child *dentry, name string) {
+	d.IncRef() // reference held by child on its parent
+	child.parent = d
+	child.name = name
+	if d.children == nil {
+		d.children = make(map[string]*dentry)
+	}
+	d.children[name] = child
+}
+
 // Preconditions: d.dirMu must be locked. d.isDir(). fs.opts.interop !=
 // InteropModeShared.
 func (d *dentry) cacheNegativeChildLocked(name string) {
-	if d.negativeChildren == nil {
-		d.negativeChildren = make(map[string]struct{})
+	if d.children == nil {
+		d.children = make(map[string]*dentry)
 	}
-	d.negativeChildren[name] = struct{}{}
+	d.children[name] = nil
 }
 
 type directoryFD struct {
@@ -80,34 +92,32 @@ func (fd *directoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallba
 
 // Preconditions: d.isDir(). There exists at least one directoryFD representing d.
 func (d *dentry) getDirents(ctx context.Context) ([]vfs.Dirent, error) {
-	// 9P2000.L's readdir does not specify behavior in the presence of
-	// concurrent mutation of an iterated directory, so implementations may
-	// duplicate or omit entries in this case, which violates POSIX semantics.
-	// Thus we read all directory entries while holding d.dirMu to exclude
-	// directory mutations. (Note that it is impossible for the client to
-	// exclude concurrent mutation from other remote filesystem users. Since
-	// there is no way to detect if the server has incorrectly omitted
-	// directory entries, we simply assume that the server is well-behaved
-	// under InteropModeShared.) This is inconsistent with Linux (which appears
-	// to assume that directory fids have the correct semantics, and translates
-	// struct file_operations::readdir calls directly to readdir RPCs), but is
-	// consistent with VFS1.
-	//
-	// NOTE(b/135560623): In particular, some gofer implementations may not
-	// retain state between calls to Readdir, so may not provide a coherent
-	// directory stream across in the presence of mutation.
-
+	// NOTE(b/135560623): 9P2000.L's readdir does not specify behavior in the
+	// presence of concurrent mutation of an iterated directory, so
+	// implementations may duplicate or omit entries in this case, which
+	// violates POSIX semantics. Thus we read all directory entries while
+	// holding d.dirMu to exclude directory mutations. (Note that it is
+	// impossible for the client to exclude concurrent mutation from other
+	// remote filesystem users. Since there is no way to detect if the server
+	// has incorrectly omitted directory entries, we simply assume that the
+	// server is well-behaved under InteropModeShared.) This is inconsistent
+	// with Linux (which appears to assume that directory fids have the correct
+	// semantics, and translates struct file_operations::readdir calls directly
+	// to readdir RPCs), but is consistent with VFS1.
+
+	// filesystem.renameMu is needed for d.parent, and must be locked before
+	// dentry.dirMu.
 	d.fs.renameMu.RLock()
-	defer d.fs.renameMu.RUnlock()
 	d.dirMu.Lock()
 	defer d.dirMu.Unlock()
 	if d.dirents != nil {
+		d.fs.renameMu.RUnlock()
 		return d.dirents, nil
 	}
 
 	// It's not clear if 9P2000.L's readdir is expected to return "." and "..",
 	// so we generate them here.
-	parent := d.vfsd.ParentOrSelf().Impl().(*dentry)
+	parent := genericParentOrSelf(d)
 	dirents := []vfs.Dirent{
 		{
 			Name:    ".",
@@ -122,6 +132,7 @@ func (d *dentry) getDirents(ctx context.Context) ([]vfs.Dirent, error) {
 			NextOff: 2,
 		},
 	}
+	d.fs.renameMu.RUnlock()
 	off := uint64(0)
 	const count = 64 * 1024 // for consistency with the vfs1 client
 	d.handleMu.RLock()
diff --git a/pkg/sentry/fsimpl/gofer/filesystem.go b/pkg/sentry/fsimpl/gofer/filesystem.go
index cd744bf5e..43e863c61 100755
--- a/pkg/sentry/fsimpl/gofer/filesystem.go
+++ b/pkg/sentry/fsimpl/gofer/filesystem.go
@@ -116,6 +116,8 @@ func putDentrySlice(ds *[]*dentry) {
 // Preconditions: fs.renameMu must be locked. d.dirMu must be locked.
 // !rp.Done(). If fs.opts.interop == InteropModeShared, then d's cached
 // metadata must be up to date.
+//
+// Postconditions: The returned dentry's cached metadata is up to date.
 func (fs *filesystem) stepLocked(ctx context.Context, rp *vfs.ResolvingPath, d *dentry, ds **[]*dentry) (*dentry, error) {
 	if !d.isDir() {
 		return nil, syserror.ENOTDIR
@@ -130,39 +132,42 @@ afterSymlink:
 		return d, nil
 	}
 	if name == ".." {
-		parentVFSD, err := rp.ResolveParent(&d.vfsd)
-		if err != nil {
+		if isRoot, err := rp.CheckRoot(&d.vfsd); err != nil {
+			return nil, err
+		} else if isRoot || d.parent == nil {
+			rp.Advance()
+			return d, nil
+		}
+		// We must assume that d.parent is correct, because if d has been moved
+		// elsewhere in the remote filesystem so that its parent has changed,
+		// we have no way of determining its new parent's location in the
+		// filesystem.
+		//
+		// Call rp.CheckMount() before updating d.parent's metadata, since if
+		// we traverse to another mount then d.parent's metadata is irrelevant.
+		if err := rp.CheckMount(&d.parent.vfsd); err != nil {
 			return nil, err
 		}
-		parent := parentVFSD.Impl().(*dentry)
-		if fs.opts.interop == InteropModeShared {
-			// We must assume that parentVFSD is correct, because if d has been
-			// moved elsewhere in the remote filesystem so that its parent has
-			// changed, we have no way of determining its new parent's location
-			// in the filesystem. Get updated metadata for parentVFSD.
-			_, attrMask, attr, err := parent.file.getAttr(ctx, dentryAttrMask())
+		if fs.opts.interop == InteropModeShared && d != d.parent {
+			_, attrMask, attr, err := d.parent.file.getAttr(ctx, dentryAttrMask())
 			if err != nil {
 				return nil, err
 			}
-			parent.updateFromP9Attrs(attrMask, &attr)
+			d.parent.updateFromP9Attrs(attrMask, &attr)
 		}
 		rp.Advance()
-		return parent, nil
+		return d.parent, nil
 	}
-	childVFSD, err := rp.ResolveChild(&d.vfsd, name)
-	if err != nil {
-		return nil, err
-	}
-	// FIXME(jamieliu): Linux performs revalidation before mount lookup
-	// (fs/namei.c:lookup_fast() => __d_lookup_rcu(), d_revalidate(),
-	// __follow_mount_rcu()).
-	child, err := fs.revalidateChildLocked(ctx, rp.VirtualFilesystem(), d, name, childVFSD, ds)
+	child, err := fs.getChildLocked(ctx, rp.VirtualFilesystem(), d, name, ds)
 	if err != nil {
 		return nil, err
 	}
 	if child == nil {
 		return nil, syserror.ENOENT
 	}
+	if err := rp.CheckMount(&child.vfsd); err != nil {
+		return nil, err
+	}
 	if child.isSymlink() && rp.ShouldFollowSymlink() {
 		target, err := child.readlink(ctx, rp.Mount())
 		if err != nil {
@@ -177,38 +182,37 @@ afterSymlink:
 	return child, nil
 }
 
-// revalidateChildLocked must be called after a call to parent.vfsd.Child(name)
-// or vfs.ResolvingPath.ResolveChild(name) returns childVFSD (which may be
-// nil) to verify that the returned child (or lack thereof) is correct. If no file
-// exists at name, revalidateChildLocked returns (nil, nil).
+// getChildLocked returns a dentry representing the child of parent with the
+// given name. If no such child exists, getChildLocked returns (nil, nil).
 //
 // Preconditions: fs.renameMu must be locked. parent.dirMu must be locked.
 // parent.isDir(). name is not "." or "..".
 //
-// Postconditions: If revalidateChildLocked returns a non-nil dentry, its
-// cached metadata is up to date.
-func (fs *filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.VirtualFilesystem, parent *dentry, name string, childVFSD *vfs.Dentry, ds **[]*dentry) (*dentry, error) {
-	if childVFSD != nil && fs.opts.interop != InteropModeShared {
-		// We have a cached dentry that is assumed to be correct.
-		return childVFSD.Impl().(*dentry), nil
-	}
-	// We either don't have a cached dentry or need to verify that it's still
-	// correct, either of which requires a remote lookup. Check if this name is
-	// valid before performing the lookup.
+// Postconditions: If getChildLocked returns a non-nil dentry, its cached
+// metadata is up to date.
+func (fs *filesystem) getChildLocked(ctx context.Context, vfsObj *vfs.VirtualFilesystem, parent *dentry, name string, ds **[]*dentry) (*dentry, error) {
 	if len(name) > maxFilenameLen {
 		return nil, syserror.ENAMETOOLONG
 	}
-	// Check if we've already cached this lookup with a negative result.
-	if _, ok := parent.negativeChildren[name]; ok {
-		return nil, nil
+	child, ok := parent.children[name]
+	if ok && fs.opts.interop != InteropModeShared {
+		// Whether child is nil or not, it is cached information that is
+		// assumed to be correct.
+		return child, nil
 	}
-	// Perform the remote lookup.
+	// We either don't have cached information or need to verify that it's
+	// still correct, either of which requires a remote lookup. Check if this
+	// name is valid before performing the lookup.
+	return fs.revalidateChildLocked(ctx, vfsObj, parent, name, child, ds)
+}
+
+// Preconditions: As for getChildLocked.
+func (fs *filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.VirtualFilesystem, parent *dentry, name string, child *dentry, ds **[]*dentry) (*dentry, error) {
 	qid, file, attrMask, attr, err := parent.file.walkGetAttrOne(ctx, name)
 	if err != nil && err != syserror.ENOENT {
 		return nil, err
 	}
-	if childVFSD != nil {
-		child := childVFSD.Impl().(*dentry)
+	if child != nil {
 		if !file.isNil() && qid.Path == child.ino {
 			// The file at this path hasn't changed. Just update cached
 			// metadata.
@@ -219,9 +223,8 @@ func (fs *filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.Vir
 		// The file at this path has changed or no longer exists. Remove
 		// the stale dentry from the tree, and re-evaluate its caching
 		// status (i.e. if it has 0 references, drop it).
-		vfsObj.ForceDeleteDentry(childVFSD)
+		vfsObj.InvalidateDentry(&child.vfsd)
 		*ds = appendDentry(*ds, child)
-		childVFSD = nil
 	}
 	if file.isNil() {
 		// No file exists at this path now. Cache the negative lookup if
@@ -232,13 +235,12 @@ func (fs *filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.Vir
 		return nil, nil
 	}
 	// Create a new dentry representing the file.
-	child, err := fs.newDentry(ctx, file, qid, attrMask, &attr)
+	child, err = fs.newDentry(ctx, file, qid, attrMask, &attr)
 	if err != nil {
 		file.close(ctx)
 		return nil, err
 	}
-	parent.IncRef() // reference held by child on its parent
-	parent.vfsd.InsertChild(&child.vfsd, name)
+	parent.cacheNewChildLocked(child, name)
 	// For now, child has 0 references, so our caller should call
 	// child.checkCachingLocked().
 	*ds = appendDentry(*ds, child)
@@ -318,9 +320,6 @@ func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir
 	if err := parent.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil {
 		return err
 	}
-	if parent.isDeleted() {
-		return syserror.ENOENT
-	}
 	name := rp.Component()
 	if name == "." || name == ".." {
 		return syserror.EEXIST
@@ -331,6 +330,9 @@ func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir
 	if !dir && rp.MustBeDir() {
 		return syserror.ENOENT
 	}
+	if parent.isDeleted() {
+		return syserror.ENOENT
+	}
 	mnt := rp.Mount()
 	if err := mnt.CheckBeginWrite(); err != nil {
 		return err
@@ -348,7 +350,7 @@ func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir
 		// it's used.
 		return create(parent, name)
 	}
-	if parent.vfsd.Child(name) != nil {
+	if child := parent.children[name]; child != nil {
 		return syserror.EEXIST
 	}
 	// No cached dentry exists; however, there might still be an existing file
@@ -356,10 +358,11 @@ func (fs *filesystem) doCreateAt(ctx context.Context, rp *vfs.ResolvingPath, dir
 	if err := create(parent, name); err != nil {
 		return err
 	}
-	if fs.opts.interop != InteropModeShared {
-		parent.touchCMtime()
-	}
-	delete(parent.negativeChildren, name)
+	parent.touchCMtime()
+	// Either parent.children[name] doesn't exist (in which case this is a
+	// no-op) or is nil (in which case this erases the now-stale information
+	// that the file doesn't exist).
+	delete(parent.children, name)
 	parent.dirents = nil
 	return nil
 }
@@ -407,56 +410,55 @@ func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir b
 	defer mntns.DecRef()
 	parent.dirMu.Lock()
 	defer parent.dirMu.Unlock()
-	childVFSD := parent.vfsd.Child(name)
-	var child *dentry
+	child, ok := parent.children[name]
+	if ok && child == nil {
+		return syserror.ENOENT
+	}
 	// We only need a dentry representing the file at name if it can be a mount
-	// point. If childVFSD is nil, then it can't be a mount point. If childVFSD
-	// is non-nil but stale, the actual file can't be a mount point either; we
+	// point. If child is nil, then it can't be a mount point. If child is
+	// non-nil but stale, the actual file can't be a mount point either; we
 	// detect this case by just speculatively calling PrepareDeleteDentry and
 	// only revalidating the dentry if that fails (indicating that the existing
 	// dentry is a mount point).
-	if childVFSD != nil {
-		child = childVFSD.Impl().(*dentry)
-		if err := vfsObj.PrepareDeleteDentry(mntns, childVFSD); err != nil {
-			child, err = fs.revalidateChildLocked(ctx, vfsObj, parent, name, childVFSD, &ds)
+	if child != nil {
+		if err := vfsObj.PrepareDeleteDentry(mntns, &child.vfsd); err != nil {
+			if fs.opts.interop != InteropModeShared {
+				return err
+			}
+			child, err = fs.revalidateChildLocked(ctx, vfsObj, parent, name, child, &ds)
 			if err != nil {
 				return err
 			}
 			if child != nil {
-				childVFSD = &child.vfsd
-				if err := vfsObj.PrepareDeleteDentry(mntns, childVFSD); err != nil {
+				if err := vfsObj.PrepareDeleteDentry(mntns, &child.vfsd); err != nil {
 					return err
 				}
-			} else {
-				childVFSD = nil
 			}
 		}
-	} else if _, ok := parent.negativeChildren[name]; ok {
-		return syserror.ENOENT
 	}
 	flags := uint32(0)
 	if dir {
 		if child != nil && !child.isDir() {
-			vfsObj.AbortDeleteDentry(childVFSD)
+			vfsObj.AbortDeleteDentry(&child.vfsd)
 			return syserror.ENOTDIR
 		}
 		flags = linux.AT_REMOVEDIR
 	} else {
 		if child != nil && child.isDir() {
-			vfsObj.AbortDeleteDentry(childVFSD)
+			vfsObj.AbortDeleteDentry(&child.vfsd)
 			return syserror.EISDIR
 		}
 		if rp.MustBeDir() {
-			if childVFSD != nil {
-				vfsObj.AbortDeleteDentry(childVFSD)
+			if child != nil {
+				vfsObj.AbortDeleteDentry(&child.vfsd)
 			}
 			return syserror.ENOTDIR
 		}
 	}
 	err = parent.file.unlinkAt(ctx, name, flags)
 	if err != nil {
-		if childVFSD != nil {
-			vfsObj.AbortDeleteDentry(childVFSD)
+		if child != nil {
+			vfsObj.AbortDeleteDentry(&child.vfsd)
 		}
 		return err
 	}
@@ -467,10 +469,12 @@ func (fs *filesystem) unlinkAt(ctx context.Context, rp *vfs.ResolvingPath, dir b
 		}
 		parent.cacheNegativeChildLocked(name)
 		parent.dirents = nil
+	} else {
+		delete(parent.children, name)
 	}
 	if child != nil {
 		child.setDeleted()
-		vfsObj.CommitDeleteDentry(childVFSD)
+		vfsObj.CommitDeleteDentry(&child.vfsd)
 		ds = appendDentry(ds, child)
 	}
 	return nil
@@ -806,16 +810,14 @@ func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.Resolving
 	// eligible for caching yet, so we don't need to append to a dentry slice.)
 	child.refs = 1
 	// Insert the dentry into the tree.
-	d.IncRef() // reference held by child on its parent d
-	d.vfsd.InsertChild(&child.vfsd, name)
+	d.cacheNewChildLocked(child, name)
 	if d.fs.opts.interop != InteropModeShared {
-		delete(d.negativeChildren, name)
+		d.touchCMtime()
 		d.dirents = nil
 	}
 
 	// Finally, construct a file description representing the created file.
 	var childVFSFD *vfs.FileDescription
-	mnt.IncRef()
 	if useRegularFileFD {
 		fd := &regularFileFD{}
 		if err := fd.vfsfd.Init(fd, opts.Flags, mnt, &child.vfsd, &vfs.FileDescriptionOptions{
@@ -840,9 +842,6 @@ func (d *dentry) createAndOpenChildLocked(ctx context.Context, rp *vfs.Resolving
 		}
 		childVFSFD = &fd.vfsfd
 	}
-	if d.fs.opts.interop != InteropModeShared {
-		d.touchCMtime()
-	}
 	return childVFSFD, nil
 }
 
@@ -902,7 +901,7 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 	// directory, we need to check for write permission on it.
 	oldParent.dirMu.Lock()
 	defer oldParent.dirMu.Unlock()
-	renamed, err := fs.revalidateChildLocked(ctx, vfsObj, oldParent, oldName, oldParent.vfsd.Child(oldName), &ds)
+	renamed, err := fs.getChildLocked(ctx, vfsObj, oldParent, oldName, &ds)
 	if err != nil {
 		return err
 	}
@@ -910,7 +909,7 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 		return syserror.ENOENT
 	}
 	if renamed.isDir() {
-		if renamed == newParent || renamed.vfsd.IsAncestorOf(&newParent.vfsd) {
+		if renamed == newParent || genericIsAncestorDentry(renamed, newParent) {
 			return syserror.EINVAL
 		}
 		if oldParent != newParent {
@@ -934,16 +933,17 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 	if newParent.isDeleted() {
 		return syserror.ENOENT
 	}
-	replacedVFSD := newParent.vfsd.Child(newName)
-	var replaced *dentry
+	replaced := newParent.children[newName]
 	// This is similar to unlinkAt, except:
 	//
-	// - We revalidate the replaced dentry unconditionally for simplicity.
+	// - If a dentry exists for the file to be replaced, we revalidate it
+	// unconditionally (instead of only if PrepareRenameDentry fails) for
+	// simplicity.
 	//
 	// - If rp.MustBeDir(), then we need a dentry representing the replaced
 	// file regardless to confirm that it's a directory.
-	if replacedVFSD != nil || rp.MustBeDir() {
-		replaced, err = fs.revalidateChildLocked(ctx, vfsObj, newParent, newName, replacedVFSD, &ds)
+	if replaced != nil || rp.MustBeDir() {
+		replaced, err = fs.getChildLocked(ctx, rp.VirtualFilesystem(), newParent, newName, &ds)
 		if err != nil {
 			return err
 		}
@@ -957,11 +957,12 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 					return syserror.ENOTDIR
 				}
 			}
-			replacedVFSD = &replaced.vfsd
-		} else {
-			replacedVFSD = nil
 		}
 	}
+	var replacedVFSD *vfs.Dentry
+	if replaced != nil {
+		replacedVFSD = &replaced.vfsd
+	}
 
 	if oldParent == newParent && oldName == newName {
 		return nil
@@ -978,7 +979,6 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 	if fs.opts.interop != InteropModeShared {
 		oldParent.cacheNegativeChildLocked(oldName)
 		oldParent.dirents = nil
-		delete(newParent.negativeChildren, newName)
 		newParent.dirents = nil
 		if renamed.isDir() {
 			oldParent.decLinks()
@@ -987,8 +987,24 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 		oldParent.touchCMtime()
 		newParent.touchCMtime()
 		renamed.touchCtime()
+	} else {
+		delete(oldParent.children, oldName)
+	}
+	if oldParent != newParent {
+		appendDentry(ds, oldParent)
+		newParent.IncRef()
+	}
+	renamed.parent = newParent
+	renamed.name = newName
+	if newParent.children == nil {
+		newParent.children = make(map[string]*dentry)
+	}
+	newParent.children[newName] = renamed
+	if replaced != nil {
+		replaced.setDeleted()
+		appendDentry(ds, replaced)
 	}
-	vfsObj.CommitRenameReplaceDentry(&renamed.vfsd, &newParent.vfsd, newName, replacedVFSD)
+	vfsObj.CommitRenameReplaceDentry(&renamed.vfsd, replacedVFSD)
 	return nil
 }
 
@@ -1131,5 +1147,5 @@ func (fs *filesystem) RemovexattrAt(ctx context.Context, rp *vfs.ResolvingPath,
 func (fs *filesystem) PrependPath(ctx context.Context, vfsroot, vd vfs.VirtualDentry, b *fspath.Builder) error {
 	fs.renameMu.RLock()
 	defer fs.renameMu.RUnlock()
-	return vfs.GenericPrependPath(vfsroot, vd, b)
+	return genericPrependPath(vfsroot, vd.Mount(), vd.Dentry().Impl().(*dentry), b)
 }
diff --git a/pkg/sentry/fsimpl/gofer/fstree.go b/pkg/sentry/fsimpl/gofer/fstree.go
new file mode 100755
index 000000000..9ef0dd8c8
--- /dev/null
+++ b/pkg/sentry/fsimpl/gofer/fstree.go
@@ -0,0 +1,45 @@
+package gofer
+
+import (
+	"gvisor.dev/gvisor/pkg/fspath"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
+)
+
+// IsAncestorDentry returns true if d is an ancestor of d2; that is, d is
+// either d2's parent or an ancestor of d2's parent.
+func genericIsAncestorDentry(d, d2 *dentry) bool {
+	for {
+		if d2.parent == d {
+			return true
+		}
+		if d2.parent == d2 {
+			return false
+		}
+		d2 = d2.parent
+	}
+}
+
+// ParentOrSelf returns d.parent. If d.parent is nil, ParentOrSelf returns d.
+func genericParentOrSelf(d *dentry) *dentry {
+	if d.parent != nil {
+		return d.parent
+	}
+	return d
+}
+
+// PrependPath is a generic implementation of FilesystemImpl.PrependPath().
+func genericPrependPath(vfsroot vfs.VirtualDentry, mnt *vfs.Mount, d *dentry, b *fspath.Builder) error {
+	for {
+		if mnt == vfsroot.Mount() && &d.vfsd == vfsroot.Dentry() {
+			return vfs.PrependPathAtVFSRootError{}
+		}
+		if &d.vfsd == mnt.Root() {
+			return nil
+		}
+		if d.parent == nil {
+			return vfs.PrependPathAtNonMountRootError{}
+		}
+		b.PrependComponent(d.name)
+		d = d.parent
+	}
+}
diff --git a/pkg/sentry/fsimpl/gofer/gofer.go b/pkg/sentry/fsimpl/gofer/gofer.go
index 2485cdb53..293df2545 100755
--- a/pkg/sentry/fsimpl/gofer/gofer.go
+++ b/pkg/sentry/fsimpl/gofer/gofer.go
@@ -452,6 +452,16 @@ type dentry struct {
 	// fs is the owning filesystem. fs is immutable.
 	fs *filesystem
 
+	// parent is this dentry's parent directory. Each dentry holds a reference
+	// on its parent. If this dentry is a filesystem root, parent is nil.
+	// parent is protected by filesystem.renameMu.
+	parent *dentry
+
+	// name is the name of this dentry in its parent. If this dentry is a
+	// filesystem root, name is the empty string. name is protected by
+	// filesystem.renameMu.
+	name string
+
 	// We don't support hard links, so each dentry maps 1:1 to an inode.
 
 	// file is the unopened p9.File that backs this dentry. file is immutable.
@@ -469,10 +479,15 @@ type dentry struct {
 
 	dirMu sync.Mutex
 
-	// If this dentry represents a directory, and InteropModeShared is not in
-	// effect, negativeChildren is a set of child names in this directory that
-	// are known not to exist. negativeChildren is protected by dirMu.
-	negativeChildren map[string]struct{}
+	// If this dentry represents a directory, children contains:
+	//
+	// - Mappings of child filenames to dentries representing those children.
+	//
+	// - Mappings of child filenames that are known not to exist to nil
+	// dentries (only if InteropModeShared is not in effect).
+	//
+	// children is protected by dirMu.
+	children map[string]*dentry
 
 	// If this dentry represents a directory, InteropModeShared is not in
 	// effect, and dirents is not nil, it is a cache of all entries in the
@@ -910,9 +925,9 @@ func (d *dentry) checkCachingLocked() {
 		// Dentry has already been destroyed.
 		return
 	}
-	// Non-child dentries with zero references are no longer reachable by path
-	// resolution and should be dropped immediately.
-	if d.vfsd.Parent() == nil || d.vfsd.IsDisowned() {
+	// Deleted and invalidated dentries with zero references are no longer
+	// reachable by path resolution and should be dropped immediately.
+	if d.vfsd.IsDead() {
 		if d.cached {
 			d.fs.cachedDentries.Remove(d)
 			d.fs.cachedDentriesLen--
@@ -937,28 +952,26 @@ func (d *dentry) checkCachingLocked() {
 		d.fs.cachedDentries.Remove(victim)
 		d.fs.cachedDentriesLen--
 		victim.cached = false
-		// victim.refs may have become non-zero from an earlier path
-		// resolution since it was inserted into fs.cachedDentries; see
-		// dentry.incRefLocked(). Either way, we brought
-		// fs.cachedDentriesLen back down to fs.opts.maxCachedDentries, so
-		// we don't loop.
+		// victim.refs may have become non-zero from an earlier path resolution
+		// since it was inserted into fs.cachedDentries.
 		if atomic.LoadInt64(&victim.refs) == 0 {
-			if victimParentVFSD := victim.vfsd.Parent(); victimParentVFSD != nil {
-				victimParent := victimParentVFSD.Impl().(*dentry)
-				victimParent.dirMu.Lock()
-				if !victim.vfsd.IsDisowned() {
-					// victim can't be a mount point (in any mount
-					// namespace), since VFS holds references on mount
-					// points.
-					d.fs.vfsfs.VirtualFilesystem().ForceDeleteDentry(&victim.vfsd)
+			if victim.parent != nil {
+				victim.parent.dirMu.Lock()
+				if !victim.vfsd.IsDead() {
+					// Note that victim can't be a mount point (in any mount
+					// namespace), since VFS holds references on mount points.
+					d.fs.vfsfs.VirtualFilesystem().InvalidateDentry(&victim.vfsd)
+					delete(victim.parent.children, victim.name)
 					// We're only deleting the dentry, not the file it
 					// represents, so we don't need to update
 					// victimParent.dirents etc.
 				}
-				victimParent.dirMu.Unlock()
+				victim.parent.dirMu.Unlock()
 			}
 			victim.destroyLocked()
 		}
+		// Whether or not victim was destroyed, we brought fs.cachedDentriesLen
+		// back down to fs.opts.maxCachedDentries, so we don't loop.
 	}
 }
 
@@ -1005,12 +1018,11 @@ func (d *dentry) destroyLocked() {
 	d.fs.syncMu.Lock()
 	delete(d.fs.dentries, d)
 	d.fs.syncMu.Unlock()
-	// Drop the reference held by d on its parent.
-	if parentVFSD := d.vfsd.Parent(); parentVFSD != nil {
-		parent := parentVFSD.Impl().(*dentry)
-		// This is parent.DecRef() without recursive locking of d.fs.renameMu.
-		if refs := atomic.AddInt64(&parent.refs, -1); refs == 0 {
-			parent.checkCachingLocked()
+	// Drop the reference held by d on its parent without recursively locking
+	// d.fs.renameMu.
+	if d.parent != nil {
+		if refs := atomic.AddInt64(&d.parent.refs, -1); refs == 0 {
+			d.parent.checkCachingLocked()
 		} else if refs < 0 {
 			panic("gofer.dentry.DecRef() called without holding a reference")
 		}
diff --git a/pkg/sentry/fsimpl/kernfs/fd_impl_util.go b/pkg/sentry/fsimpl/kernfs/fd_impl_util.go
index bfa786c88..e8a4670b8 100755
--- a/pkg/sentry/fsimpl/kernfs/fd_impl_util.go
+++ b/pkg/sentry/fsimpl/kernfs/fd_impl_util.go
@@ -129,7 +129,7 @@ func (fd *GenericDirectoryFD) IterDirents(ctx context.Context, cb vfs.IterDirent
 
 	// Handle "..".
 	if fd.off == 1 {
-		parentInode := vfsd.ParentOrSelf().Impl().(*Dentry).inode
+		parentInode := genericParentOrSelf(vfsd.Impl().(*Dentry)).inode
 		stat, err := parentInode.Stat(vfsFS, opts)
 		if err != nil {
 			return err
diff --git a/pkg/sentry/fsimpl/kernfs/filesystem.go b/pkg/sentry/fsimpl/kernfs/filesystem.go
index baf81b4db..01c23d192 100755
--- a/pkg/sentry/fsimpl/kernfs/filesystem.go
+++ b/pkg/sentry/fsimpl/kernfs/filesystem.go
@@ -56,25 +56,28 @@ afterSymlink:
 		return vfsd, nil
 	}
 	if name == ".." {
-		nextVFSD, err := rp.ResolveParent(vfsd)
-		if err != nil {
+		if isRoot, err := rp.CheckRoot(vfsd); err != nil {
+			return nil, err
+		} else if isRoot || d.parent == nil {
+			rp.Advance()
+			return vfsd, nil
+		}
+		if err := rp.CheckMount(&d.parent.vfsd); err != nil {
 			return nil, err
 		}
 		rp.Advance()
-		return nextVFSD, nil
+		return &d.parent.vfsd, nil
 	}
 	if len(name) > linux.NAME_MAX {
 		return nil, syserror.ENAMETOOLONG
 	}
 	d.dirMu.Lock()
-	nextVFSD, err := rp.ResolveChild(vfsd, name)
+	next, err := fs.revalidateChildLocked(ctx, rp.VirtualFilesystem(), d, name, d.children[name])
+	d.dirMu.Unlock()
 	if err != nil {
-		d.dirMu.Unlock()
 		return nil, err
 	}
-	next, err := fs.revalidateChildLocked(ctx, rp.VirtualFilesystem(), d, name, nextVFSD)
-	d.dirMu.Unlock()
-	if err != nil {
+	if err := rp.CheckMount(&next.vfsd); err != nil {
 		return nil, err
 	}
 	// Resolve any symlink at current path component.
@@ -108,17 +111,17 @@ afterSymlink:
 // parent.dirMu must be locked. parent.isDir(). name is not "." or "..".
 //
 // Postconditions: Caller must call fs.processDeferredDecRefs*.
-func (fs *Filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.VirtualFilesystem, parent *Dentry, name string, childVFSD *vfs.Dentry) (*Dentry, error) {
-	if childVFSD != nil {
+func (fs *Filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.VirtualFilesystem, parent *Dentry, name string, child *Dentry) (*Dentry, error) {
+	if child != nil {
 		// Cached dentry exists, revalidate.
-		child := childVFSD.Impl().(*Dentry)
 		if !child.inode.Valid(ctx) {
-			vfsObj.ForceDeleteDentry(childVFSD)
-			fs.deferDecRef(childVFSD) // Reference from Lookup.
-			childVFSD = nil
+			delete(parent.children, name)
+			vfsObj.InvalidateDentry(&child.vfsd)
+			fs.deferDecRef(&child.vfsd) // Reference from Lookup.
+			child = nil
 		}
 	}
-	if childVFSD == nil {
+	if child == nil {
 		// Dentry isn't cached; it either doesn't exist or failed
 		// revalidation. Attempt to resolve it via Lookup.
 		//
@@ -126,15 +129,15 @@ func (fs *Filesystem) revalidateChildLocked(ctx context.Context, vfsObj *vfs.Vir
 		// *(kernfs.)Dentry, not *vfs.Dentry, since (kernfs.)Filesystem assumes
 		// that all dentries in the filesystem are (kernfs.)Dentry and performs
 		// vfs.DentryImpl casts accordingly.
-		var err error
-		childVFSD, err = parent.inode.Lookup(ctx, name)
+		childVFSD, err := parent.inode.Lookup(ctx, name)
 		if err != nil {
 			return nil, err
 		}
 		// Reference on childVFSD dropped by a corresponding Valid.
-		parent.insertChildLocked(name, childVFSD)
+		child = childVFSD.Impl().(*Dentry)
+		parent.insertChildLocked(name, child)
 	}
-	return childVFSD.Impl().(*Dentry), nil
+	return child, nil
 }
 
 // walkExistingLocked resolves rp to an existing file.
@@ -203,14 +206,11 @@ func checkCreateLocked(ctx context.Context, rp *vfs.ResolvingPath, parentVFSD *v
 	if len(pc) > linux.NAME_MAX {
 		return "", syserror.ENAMETOOLONG
 	}
-	childVFSD, err := rp.ResolveChild(parentVFSD, pc)
-	if err != nil {
-		return "", err
-	}
-	if childVFSD != nil {
+	// FIXME(gvisor.dev/issue/1193): Data race due to not holding dirMu.
+	if _, ok := parentVFSD.Impl().(*Dentry).children[pc]; ok {
 		return "", syserror.EEXIST
 	}
-	if parentVFSD.IsDisowned() {
+	if parentVFSD.IsDead() {
 		return "", syserror.ENOENT
 	}
 	return pc, nil
@@ -220,14 +220,14 @@ func checkCreateLocked(ctx context.Context, rp *vfs.ResolvingPath, parentVFSD *v
 //
 // Preconditions: Filesystem.mu must be locked for at least reading.
 func checkDeleteLocked(ctx context.Context, rp *vfs.ResolvingPath, vfsd *vfs.Dentry) error {
-	parentVFSD := vfsd.Parent()
-	if parentVFSD == nil {
+	parent := vfsd.Impl().(*Dentry).parent
+	if parent == nil {
 		return syserror.EBUSY
 	}
-	if parentVFSD.IsDisowned() {
+	if parent.vfsd.IsDead() {
 		return syserror.ENOENT
 	}
-	if err := parentVFSD.Impl().(*Dentry).inode.CheckPermissions(ctx, rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil {
+	if err := parent.inode.CheckPermissions(ctx, rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil {
 		return err
 	}
 	return nil
@@ -321,11 +321,11 @@ func (fs *Filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.
 		return syserror.EPERM
 	}
 
-	child, err := parentInode.NewLink(ctx, pc, d.inode)
+	childVFSD, err := parentInode.NewLink(ctx, pc, d.inode)
 	if err != nil {
 		return err
 	}
-	parentVFSD.Impl().(*Dentry).InsertChild(pc, child)
+	parentVFSD.Impl().(*Dentry).InsertChild(pc, childVFSD.Impl().(*Dentry))
 	return nil
 }
 
@@ -349,11 +349,11 @@ func (fs *Filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts v
 		return err
 	}
 	defer rp.Mount().EndWrite()
-	child, err := parentInode.NewDir(ctx, pc, opts)
+	childVFSD, err := parentInode.NewDir(ctx, pc, opts)
 	if err != nil {
 		return err
 	}
-	parentVFSD.Impl().(*Dentry).InsertChild(pc, child)
+	parentVFSD.Impl().(*Dentry).InsertChild(pc, childVFSD.Impl().(*Dentry))
 	return nil
 }
 
@@ -377,11 +377,11 @@ func (fs *Filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts v
 		return err
 	}
 	defer rp.Mount().EndWrite()
-	new, err := parentInode.NewNode(ctx, pc, opts)
+	newVFSD, err := parentInode.NewNode(ctx, pc, opts)
 	if err != nil {
 		return err
 	}
-	parentVFSD.Impl().(*Dentry).InsertChild(pc, new)
+	parentVFSD.Impl().(*Dentry).InsertChild(pc, newVFSD.Impl().(*Dentry))
 	return nil
 }
 
@@ -449,11 +449,8 @@ afterTrailingSymlink:
 		return nil, syserror.ENAMETOOLONG
 	}
 	// Determine whether or not we need to create a file.
-	childVFSD, err := rp.ResolveChild(parentVFSD, pc)
-	if err != nil {
-		return nil, err
-	}
-	if childVFSD == nil {
+	childVFSD, err := fs.stepExistingLocked(ctx, rp, parentVFSD)
+	if err == syserror.ENOENT {
 		// Already checked for searchability above; now check for writability.
 		if err := parentInode.CheckPermissions(ctx, rp.Credentials(), vfs.MayWrite); err != nil {
 			return nil, err
@@ -463,21 +460,24 @@ afterTrailingSymlink:
 		}
 		defer rp.Mount().EndWrite()
 		// Create and open the child.
-		child, err := parentInode.NewFile(ctx, pc, opts)
+		childVFSD, err = parentInode.NewFile(ctx, pc, opts)
 		if err != nil {
 			return nil, err
 		}
+		child := childVFSD.Impl().(*Dentry)
 		parentVFSD.Impl().(*Dentry).InsertChild(pc, child)
-		return child.Impl().(*Dentry).inode.Open(rp, child, opts)
+		return child.inode.Open(rp, childVFSD, opts)
+	}
+	if err != nil {
+		return nil, err
 	}
 	// Open existing file or follow symlink.
 	if mustCreate {
 		return nil, syserror.EEXIST
 	}
-	childDentry := childVFSD.Impl().(*Dentry)
-	childInode := childDentry.inode
-	if rp.ShouldFollowSymlink() && childDentry.isSymlink() {
-		targetVD, targetPathname, err := childInode.Getlink(ctx)
+	child := childVFSD.Impl().(*Dentry)
+	if rp.ShouldFollowSymlink() && child.isSymlink() {
+		targetVD, targetPathname, err := child.inode.Getlink(ctx)
 		if err != nil {
 			return nil, err
 		}
@@ -496,10 +496,10 @@ afterTrailingSymlink:
 		// symlink target.
 		goto afterTrailingSymlink
 	}
-	if err := childInode.CheckPermissions(ctx, rp.Credentials(), ats); err != nil {
+	if err := child.inode.CheckPermissions(ctx, rp.Credentials(), ats); err != nil {
 		return nil, err
 	}
-	return childInode.Open(rp, childVFSD, opts)
+	return child.inode.Open(rp, &child.vfsd, opts)
 }
 
 // ReadlinkAt implements vfs.FilesystemImpl.ReadlinkAt.
@@ -526,15 +526,16 @@ func (fs *Filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 	noReplace := opts.Flags&linux.RENAME_NOREPLACE != 0
 
 	fs.mu.Lock()
-	defer fs.mu.Lock()
+	defer fs.processDeferredDecRefsLocked()
+	defer fs.mu.Unlock()
 
 	// Resolve the destination directory first to verify that it's on this
 	// Mount.
 	dstDirVFSD, dstDirInode, err := fs.walkParentDirLocked(ctx, rp)
-	fs.processDeferredDecRefsLocked()
 	if err != nil {
 		return err
 	}
+	dstDir := dstDirVFSD.Impl().(*Dentry)
 	mnt := rp.Mount()
 	if mnt != oldParentVD.Mount() {
 		return syserror.EXDEV
@@ -547,9 +548,8 @@ func (fs *Filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 	srcDirVFSD := oldParentVD.Dentry()
 	srcDir := srcDirVFSD.Impl().(*Dentry)
 	srcDir.dirMu.Lock()
-	src, err := fs.revalidateChildLocked(ctx, rp.VirtualFilesystem(), srcDir, oldName, srcDirVFSD.Child(oldName))
+	src, err := fs.revalidateChildLocked(ctx, rp.VirtualFilesystem(), srcDir, oldName, srcDir.children[oldName])
 	srcDir.dirMu.Unlock()
-	fs.processDeferredDecRefsLocked()
 	if err != nil {
 		return err
 	}
@@ -561,7 +561,7 @@ func (fs *Filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 	}
 
 	// Can we create the dst dentry?
-	var dstVFSD *vfs.Dentry
+	var dst *Dentry
 	pc, err := checkCreateLocked(ctx, rp, dstDirVFSD, dstDirInode)
 	switch err {
 	case nil:
@@ -571,38 +571,51 @@ func (fs *Filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 			// Won't overwrite existing node since RENAME_NOREPLACE was requested.
 			return syserror.EEXIST
 		}
-		dstVFSD, err = rp.ResolveChild(dstDirVFSD, pc)
-		if err != nil {
+		dst = dstDir.children[pc]
+		if dst == nil {
 			panic(fmt.Sprintf("Child %q for parent Dentry %+v disappeared inside atomic section?", pc, dstDirVFSD))
 		}
 	default:
 		return err
 	}
+	var dstVFSD *vfs.Dentry
+	if dst != nil {
+		dstVFSD = &dst.vfsd
+	}
 
 	mntns := vfs.MountNamespaceFromContext(ctx)
 	defer mntns.DecRef()
 	virtfs := rp.VirtualFilesystem()
 
-	srcDirDentry := srcDirVFSD.Impl().(*Dentry)
-	dstDirDentry := dstDirVFSD.Impl().(*Dentry)
-
 	// We can't deadlock here due to lock ordering because we're protected from
 	// concurrent renames by fs.mu held for writing.
-	srcDirDentry.dirMu.Lock()
-	defer srcDirDentry.dirMu.Unlock()
-	dstDirDentry.dirMu.Lock()
-	defer dstDirDentry.dirMu.Unlock()
+	srcDir.dirMu.Lock()
+	defer srcDir.dirMu.Unlock()
+	if srcDir != dstDir {
+		dstDir.dirMu.Lock()
+		defer dstDir.dirMu.Unlock()
+	}
 
 	if err := virtfs.PrepareRenameDentry(mntns, srcVFSD, dstVFSD); err != nil {
 		return err
 	}
-	srcDirInode := srcDirDentry.inode
-	replaced, err := srcDirInode.Rename(ctx, srcVFSD.Name(), pc, srcVFSD, dstDirVFSD)
+	replaced, err := srcDir.inode.Rename(ctx, src.name, pc, srcVFSD, dstDirVFSD)
 	if err != nil {
 		virtfs.AbortRenameDentry(srcVFSD, dstVFSD)
 		return err
 	}
-	virtfs.CommitRenameReplaceDentry(srcVFSD, dstDirVFSD, pc, replaced)
+	delete(srcDir.children, src.name)
+	if srcDir != dstDir {
+		fs.deferDecRef(srcDirVFSD)
+		dstDir.IncRef()
+	}
+	src.parent = dstDir
+	src.name = pc
+	if dstDir.children == nil {
+		dstDir.children = make(map[string]*Dentry)
+	}
+	dstDir.children[pc] = src
+	virtfs.CommitRenameReplaceDentry(srcVFSD, replaced)
 	return nil
 }
 
@@ -622,14 +635,15 @@ func (fs *Filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error
 	if err := checkDeleteLocked(ctx, rp, vfsd); err != nil {
 		return err
 	}
-	if !vfsd.Impl().(*Dentry).isDir() {
+	d := vfsd.Impl().(*Dentry)
+	if !d.isDir() {
 		return syserror.ENOTDIR
 	}
 	if inode.HasChildren() {
 		return syserror.ENOTEMPTY
 	}
 	virtfs := rp.VirtualFilesystem()
-	parentDentry := vfsd.Parent().Impl().(*Dentry)
+	parentDentry := d.parent
 	parentDentry.dirMu.Lock()
 	defer parentDentry.dirMu.Unlock()
 
@@ -706,11 +720,11 @@ func (fs *Filesystem) SymlinkAt(ctx context.Context, rp *vfs.ResolvingPath, targ
 		return err
 	}
 	defer rp.Mount().EndWrite()
-	child, err := parentInode.NewSymlink(ctx, pc, target)
+	childVFSD, err := parentInode.NewSymlink(ctx, pc, target)
 	if err != nil {
 		return err
 	}
-	parentVFSD.Impl().(*Dentry).InsertChild(pc, child)
+	parentVFSD.Impl().(*Dentry).InsertChild(pc, childVFSD.Impl().(*Dentry))
 	return nil
 }
 
@@ -730,11 +744,12 @@ func (fs *Filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error
 	if err := checkDeleteLocked(ctx, rp, vfsd); err != nil {
 		return err
 	}
-	if vfsd.Impl().(*Dentry).isDir() {
+	d := vfsd.Impl().(*Dentry)
+	if d.isDir() {
 		return syserror.EISDIR
 	}
 	virtfs := rp.VirtualFilesystem()
-	parentDentry := vfsd.Parent().Impl().(*Dentry)
+	parentDentry := d.parent
 	parentDentry.dirMu.Lock()
 	defer parentDentry.dirMu.Unlock()
 	mntns := vfs.MountNamespaceFromContext(ctx)
@@ -818,5 +833,5 @@ func (fs *Filesystem) RemovexattrAt(ctx context.Context, rp *vfs.ResolvingPath,
 func (fs *Filesystem) PrependPath(ctx context.Context, vfsroot, vd vfs.VirtualDentry, b *fspath.Builder) error {
 	fs.mu.RLock()
 	defer fs.mu.RUnlock()
-	return vfs.GenericPrependPath(vfsroot, vd, b)
+	return genericPrependPath(vfsroot, vd.Mount(), vd.Dentry().Impl().(*Dentry), b)
 }
diff --git a/pkg/sentry/fsimpl/kernfs/fstree.go b/pkg/sentry/fsimpl/kernfs/fstree.go
new file mode 100755
index 000000000..4c4033462
--- /dev/null
+++ b/pkg/sentry/fsimpl/kernfs/fstree.go
@@ -0,0 +1,45 @@
+package kernfs
+
+import (
+	"gvisor.dev/gvisor/pkg/fspath"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
+)
+
+// IsAncestorDentry returns true if d is an ancestor of d2; that is, d is
+// either d2's parent or an ancestor of d2's parent.
+func genericIsAncestorDentry(d, d2 *Dentry) bool {
+	for {
+		if d2.parent == d {
+			return true
+		}
+		if d2.parent == d2 {
+			return false
+		}
+		d2 = d2.parent
+	}
+}
+
+// ParentOrSelf returns d.parent. If d.parent is nil, ParentOrSelf returns d.
+func genericParentOrSelf(d *Dentry) *Dentry {
+	if d.parent != nil {
+		return d.parent
+	}
+	return d
+}
+
+// PrependPath is a generic implementation of FilesystemImpl.PrependPath().
+func genericPrependPath(vfsroot vfs.VirtualDentry, mnt *vfs.Mount, d *Dentry, b *fspath.Builder) error {
+	for {
+		if mnt == vfsroot.Mount() && &d.vfsd == vfsroot.Dentry() {
+			return vfs.PrependPathAtVFSRootError{}
+		}
+		if &d.vfsd == mnt.Root() {
+			return nil
+		}
+		if d.parent == nil {
+			return vfs.PrependPathAtNonMountRootError{}
+		}
+		b.PrependComponent(d.name)
+		d = d.parent
+	}
+}
diff --git a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
index 65f09af5d..9f526359e 100755
--- a/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
+++ b/pkg/sentry/fsimpl/kernfs/inode_impl_util.go
@@ -370,7 +370,7 @@ func (o *OrderedChildren) Populate(d *Dentry, children map[string]*Dentry) uint3
 		if err := o.Insert(name, child.VFSDentry()); err != nil {
 			panic(fmt.Sprintf("Collision when attempting to insert child %q (%+v) into %+v", name, child, d))
 		}
-		d.InsertChild(name, child.VFSDentry())
+		d.InsertChild(name, child)
 	}
 	return links
 }
diff --git a/pkg/sentry/fsimpl/kernfs/kernfs.go b/pkg/sentry/fsimpl/kernfs/kernfs.go
index ad76b9f64..f5041824f 100755
--- a/pkg/sentry/fsimpl/kernfs/kernfs.go
+++ b/pkg/sentry/fsimpl/kernfs/kernfs.go
@@ -168,17 +168,22 @@ const (
 //
 // Must be initialized by Init prior to first use.
 type Dentry struct {
-	refs.AtomicRefCount
+	vfsd vfs.Dentry
 
-	vfsd  vfs.Dentry
-	inode Inode
+	refs.AtomicRefCount
 
 	// flags caches useful information about the dentry from the inode. See the
 	// dflags* consts above. Must be accessed by atomic ops.
 	flags uint32
 
-	// dirMu protects vfsd.children for directory dentries.
-	dirMu sync.Mutex
+	parent *Dentry
+	name   string
+
+	// dirMu protects children and the names of child Dentries.
+	dirMu    sync.Mutex
+	children map[string]*Dentry
+
+	inode Inode
 }
 
 // Init initializes this dentry.
@@ -222,8 +227,8 @@ func (d *Dentry) DecRef() {
 func (d *Dentry) destroy() {
 	d.inode.DecRef() // IncRef from Init.
 	d.inode = nil
-	if parent := d.vfsd.Parent(); parent != nil {
-		parent.DecRef() // IncRef from Dentry.InsertChild.
+	if d.parent != nil {
+		d.parent.DecRef() // IncRef from Dentry.InsertChild.
 	}
 }
 
@@ -233,7 +238,7 @@ func (d *Dentry) destroy() {
 // updates the link count on d if required.
 //
 // Precondition: d must represent a directory inode.
-func (d *Dentry) InsertChild(name string, child *vfs.Dentry) {
+func (d *Dentry) InsertChild(name string, child *Dentry) {
 	d.dirMu.Lock()
 	d.insertChildLocked(name, child)
 	d.dirMu.Unlock()
@@ -243,13 +248,17 @@ func (d *Dentry) InsertChild(name string, child *vfs.Dentry) {
 // preconditions.
 //
 // Precondition: d.dirMu must be locked.
-func (d *Dentry) insertChildLocked(name string, child *vfs.Dentry) {
+func (d *Dentry) insertChildLocked(name string, child *Dentry) {
 	if !d.isDir() {
 		panic(fmt.Sprintf("InsertChild called on non-directory Dentry: %+v.", d))
 	}
-	vfsDentry := d.VFSDentry()
-	vfsDentry.IncRef() // DecRef in child's Dentry.destroy.
-	vfsDentry.InsertChild(child, name)
+	d.IncRef() // DecRef in child's Dentry.destroy.
+	child.parent = d
+	child.name = name
+	if d.children == nil {
+		d.children = make(map[string]*Dentry)
+	}
+	d.children[name] = child
 }
 
 // The Inode interface maps filesystem-level operations that operate on paths to
diff --git a/pkg/sentry/fsimpl/tmpfs/directory.go b/pkg/sentry/fsimpl/tmpfs/directory.go
index 45712c9b9..f2399981b 100755
--- a/pkg/sentry/fsimpl/tmpfs/directory.go
+++ b/pkg/sentry/fsimpl/tmpfs/directory.go
@@ -15,35 +15,77 @@
 package tmpfs
 
 import (
+	"sync/atomic"
+
 	"gvisor.dev/gvisor/pkg/abi/linux"
 	"gvisor.dev/gvisor/pkg/context"
 	"gvisor.dev/gvisor/pkg/sentry/kernel/auth"
 	"gvisor.dev/gvisor/pkg/sentry/vfs"
+	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/syserror"
 )
 
 type directory struct {
-	inode inode
+	// Since directories can't be hard-linked, each directory can only be
+	// associated with a single dentry, which we can store in the directory
+	// struct.
+	dentry dentry
+	inode  inode
+
+	// childMap maps the names of the directory's children to their dentries.
+	// childMap is protected by filesystem.mu.
+	childMap map[string]*dentry
 
-	// childList is a list containing (1) child Dentries and (2) fake Dentries
+	// numChildren is len(childMap), but accessed using atomic memory
+	// operations to avoid locking in inode.statTo().
+	numChildren int64
+
+	// childList is a list containing (1) child dentries and (2) fake dentries
 	// (with inode == nil) that represent the iteration position of
 	// directoryFDs. childList is used to support directoryFD.IterDirents()
-	// efficiently. childList is protected by filesystem.mu.
+	// efficiently. childList is protected by iterMu.
+	iterMu    sync.Mutex
 	childList dentryList
 }
 
-func (fs *filesystem) newDirectory(creds *auth.Credentials, mode linux.FileMode) *inode {
+func (fs *filesystem) newDirectory(creds *auth.Credentials, mode linux.FileMode) *directory {
 	dir := &directory{}
 	dir.inode.init(dir, fs, creds, linux.S_IFDIR|mode)
 	dir.inode.nlink = 2 // from "." and parent directory or ".." for root
-	return &dir.inode
+	dir.dentry.inode = &dir.inode
+	dir.dentry.vfsd.Init(&dir.dentry)
+	return dir
+}
+
+// Preconditions: filesystem.mu must be locked for writing. dir must not
+// already contain a child with the given name.
+func (dir *directory) insertChildLocked(child *dentry, name string) {
+	child.parent = &dir.dentry
+	child.name = name
+	if dir.childMap == nil {
+		dir.childMap = make(map[string]*dentry)
+	}
+	dir.childMap[name] = child
+	atomic.AddInt64(&dir.numChildren, 1)
+	dir.iterMu.Lock()
+	dir.childList.PushBack(child)
+	dir.iterMu.Unlock()
+}
+
+// Preconditions: filesystem.mu must be locked for writing.
+func (dir *directory) removeChildLocked(child *dentry) {
+	delete(dir.childMap, child.name)
+	atomic.AddInt64(&dir.numChildren, -1)
+	dir.iterMu.Lock()
+	dir.childList.Remove(child)
+	dir.iterMu.Unlock()
 }
 
 type directoryFD struct {
 	fileDescription
 	vfs.DirectoryFileDescriptionDefaultImpl
 
-	// Protected by filesystem.mu.
+	// Protected by directory.iterMu.
 	iter *dentry
 	off  int64
 }
@@ -51,11 +93,10 @@ type directoryFD struct {
 // Release implements vfs.FileDescriptionImpl.Release.
 func (fd *directoryFD) Release() {
 	if fd.iter != nil {
-		fs := fd.filesystem()
 		dir := fd.inode().impl.(*directory)
-		fs.mu.Lock()
+		dir.iterMu.Lock()
 		dir.childList.Remove(fd.iter)
-		fs.mu.Unlock()
+		dir.iterMu.Unlock()
 		fd.iter = nil
 	}
 }
@@ -63,10 +104,13 @@ func (fd *directoryFD) Release() {
 // IterDirents implements vfs.FileDescriptionImpl.IterDirents.
 func (fd *directoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallback) error {
 	fs := fd.filesystem()
-	vfsd := fd.vfsfd.VirtualDentry().Dentry()
+	dir := fd.inode().impl.(*directory)
 
-	fs.mu.Lock()
-	defer fs.mu.Unlock()
+	// fs.mu is required to read d.parent and dentry.name.
+	fs.mu.RLock()
+	defer fs.mu.RUnlock()
+	dir.iterMu.Lock()
+	defer dir.iterMu.Unlock()
 
 	fd.inode().touchAtime(fd.vfsfd.Mount())
 
@@ -74,15 +118,16 @@ func (fd *directoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallba
 		if err := cb.Handle(vfs.Dirent{
 			Name:    ".",
 			Type:    linux.DT_DIR,
-			Ino:     vfsd.Impl().(*dentry).inode.ino,
+			Ino:     dir.inode.ino,
 			NextOff: 1,
 		}); err != nil {
 			return err
 		}
 		fd.off++
 	}
+
 	if fd.off == 1 {
-		parentInode := vfsd.ParentOrSelf().Impl().(*dentry).inode
+		parentInode := genericParentOrSelf(&dir.dentry).inode
 		if err := cb.Handle(vfs.Dirent{
 			Name:    "..",
 			Type:    parentInode.direntType(),
@@ -94,7 +139,6 @@ func (fd *directoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallba
 		fd.off++
 	}
 
-	dir := vfsd.Impl().(*dentry).inode.impl.(*directory)
 	var child *dentry
 	if fd.iter == nil {
 		// Start iteration at the beginning of dir.
@@ -109,7 +153,7 @@ func (fd *directoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallba
 		// Skip other directoryFD iterators.
 		if child.inode != nil {
 			if err := cb.Handle(vfs.Dirent{
-				Name:    child.vfsd.Name(),
+				Name:    child.name,
 				Type:    child.inode.direntType(),
 				Ino:     child.inode.ino,
 				NextOff: fd.off + 1,
@@ -127,9 +171,9 @@ func (fd *directoryFD) IterDirents(ctx context.Context, cb vfs.IterDirentsCallba
 
 // Seek implements vfs.FileDescriptionImpl.Seek.
 func (fd *directoryFD) Seek(ctx context.Context, offset int64, whence int32) (int64, error) {
-	fs := fd.filesystem()
-	fs.mu.Lock()
-	defer fs.mu.Unlock()
+	dir := fd.inode().impl.(*directory)
+	dir.iterMu.Lock()
+	defer dir.iterMu.Unlock()
 
 	switch whence {
 	case linux.SEEK_SET:
@@ -157,8 +201,6 @@ func (fd *directoryFD) Seek(ctx context.Context, offset int64, whence int32) (in
 		remChildren = offset - 2
 	}
 
-	dir := fd.inode().impl.(*directory)
-
 	// Ensure that fd.iter exists and is not linked into dir.childList.
 	if fd.iter == nil {
 		fd.iter = &dentry{}
diff --git a/pkg/sentry/fsimpl/tmpfs/filesystem.go b/pkg/sentry/fsimpl/tmpfs/filesystem.go
index 452c4e2e0..5b62f9ebb 100755
--- a/pkg/sentry/fsimpl/tmpfs/filesystem.go
+++ b/pkg/sentry/fsimpl/tmpfs/filesystem.go
@@ -39,27 +39,43 @@ func (fs *filesystem) Sync(ctx context.Context) error {
 //
 // Preconditions: filesystem.mu must be locked. !rp.Done().
 func stepLocked(rp *vfs.ResolvingPath, d *dentry) (*dentry, error) {
-	if !d.inode.isDir() {
+	dir, ok := d.inode.impl.(*directory)
+	if !ok {
 		return nil, syserror.ENOTDIR
 	}
 	if err := d.inode.checkPermissions(rp.Credentials(), vfs.MayExec); err != nil {
 		return nil, err
 	}
 afterSymlink:
-	if len(rp.Component()) > linux.NAME_MAX {
-		return nil, syserror.ENAMETOOLONG
+	name := rp.Component()
+	if name == "." {
+		rp.Advance()
+		return d, nil
 	}
-	nextVFSD, err := rp.ResolveComponent(&d.vfsd)
-	if err != nil {
-		return nil, err
+	if name == ".." {
+		if isRoot, err := rp.CheckRoot(&d.vfsd); err != nil {
+			return nil, err
+		} else if isRoot || d.parent == nil {
+			rp.Advance()
+			return d, nil
+		}
+		if err := rp.CheckMount(&d.parent.vfsd); err != nil {
+			return nil, err
+		}
+		rp.Advance()
+		return d.parent, nil
 	}
-	if nextVFSD == nil {
-		// Since the Dentry tree is the sole source of truth for tmpfs, if it's
-		// not in the Dentry tree, it doesn't exist.
+	if len(name) > linux.NAME_MAX {
+		return nil, syserror.ENAMETOOLONG
+	}
+	child, ok := dir.childMap[name]
+	if !ok {
 		return nil, syserror.ENOENT
 	}
-	next := nextVFSD.Impl().(*dentry)
-	if symlink, ok := next.inode.impl.(*symlink); ok && rp.ShouldFollowSymlink() {
+	if err := rp.CheckMount(&child.vfsd); err != nil {
+		return nil, err
+	}
+	if symlink, ok := child.inode.impl.(*symlink); ok && rp.ShouldFollowSymlink() {
 		// TODO(gvisor.dev/issue/1197): Symlink traversals updates
 		// access time.
 		if err := rp.HandleSymlink(symlink.target); err != nil {
@@ -68,7 +84,7 @@ afterSymlink:
 		goto afterSymlink // don't check the current directory again
 	}
 	rp.Advance()
-	return next, nil
+	return child, nil
 }
 
 // walkParentDirLocked resolves all but the last path component of rp to an
@@ -80,7 +96,7 @@ afterSymlink:
 // fs/namei.c:path_parentat().
 //
 // Preconditions: filesystem.mu must be locked. !rp.Done().
-func walkParentDirLocked(rp *vfs.ResolvingPath, d *dentry) (*dentry, error) {
+func walkParentDirLocked(rp *vfs.ResolvingPath, d *dentry) (*directory, error) {
 	for !rp.Final() {
 		next, err := stepLocked(rp, d)
 		if err != nil {
@@ -88,10 +104,11 @@ func walkParentDirLocked(rp *vfs.ResolvingPath, d *dentry) (*dentry, error) {
 		}
 		d = next
 	}
-	if !d.inode.isDir() {
+	dir, ok := d.inode.impl.(*directory)
+	if !ok {
 		return nil, syserror.ENOTDIR
 	}
-	return d, nil
+	return dir, nil
 }
 
 // resolveLocked resolves rp to an existing file.
@@ -122,14 +139,14 @@ func resolveLocked(rp *vfs.ResolvingPath) (*dentry, error) {
 //
 // Preconditions: !rp.Done(). For the final path component in rp,
 // !rp.ShouldFollowSymlink().
-func (fs *filesystem) doCreateAt(rp *vfs.ResolvingPath, dir bool, create func(parent *dentry, name string) error) error {
+func (fs *filesystem) doCreateAt(rp *vfs.ResolvingPath, dir bool, create func(parentDir *directory, name string) error) error {
 	fs.mu.Lock()
 	defer fs.mu.Unlock()
-	parent, err := walkParentDirLocked(rp, rp.Start().Impl().(*dentry))
+	parentDir, err := walkParentDirLocked(rp, rp.Start().Impl().(*dentry))
 	if err != nil {
 		return err
 	}
-	if err := parent.inode.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil {
+	if err := parentDir.inode.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil {
 		return err
 	}
 	name := rp.Component()
@@ -139,19 +156,15 @@ func (fs *filesystem) doCreateAt(rp *vfs.ResolvingPath, dir bool, create func(pa
 	if len(name) > linux.NAME_MAX {
 		return syserror.ENAMETOOLONG
 	}
-	// Call parent.vfsd.Child() instead of stepLocked() or rp.ResolveChild(),
-	// because if the child exists we want to return EEXIST immediately instead
-	// of attempting symlink/mount traversal.
-	if parent.vfsd.Child(name) != nil {
+	if _, ok := parentDir.childMap[name]; ok {
 		return syserror.EEXIST
 	}
 	if !dir && rp.MustBeDir() {
 		return syserror.ENOENT
 	}
-	// In tmpfs, the only way to cause a dentry to be disowned is by removing
-	// it from the filesystem, so this check is equivalent to checking if
-	// parent has been removed.
-	if parent.vfsd.IsDisowned() {
+	// tmpfs never calls VFS.InvalidateDentry(), so parentDir.dentry can only
+	// be dead if it was deleted.
+	if parentDir.dentry.vfsd.IsDead() {
 		return syserror.ENOENT
 	}
 	mnt := rp.Mount()
@@ -159,10 +172,10 @@ func (fs *filesystem) doCreateAt(rp *vfs.ResolvingPath, dir bool, create func(pa
 		return err
 	}
 	defer mnt.EndWrite()
-	if err := create(parent, name); err != nil {
+	if err := create(parentDir, name); err != nil {
 		return err
 	}
-	parent.inode.touchCMtime()
+	parentDir.inode.touchCMtime()
 	return nil
 }
 
@@ -201,17 +214,17 @@ func (fs *filesystem) GetDentryAt(ctx context.Context, rp *vfs.ResolvingPath, op
 func (fs *filesystem) GetParentDentryAt(ctx context.Context, rp *vfs.ResolvingPath) (*vfs.Dentry, error) {
 	fs.mu.RLock()
 	defer fs.mu.RUnlock()
-	d, err := walkParentDirLocked(rp, rp.Start().Impl().(*dentry))
+	dir, err := walkParentDirLocked(rp, rp.Start().Impl().(*dentry))
 	if err != nil {
 		return nil, err
 	}
-	d.IncRef()
-	return &d.vfsd, nil
+	dir.dentry.IncRef()
+	return &dir.dentry.vfsd, nil
 }
 
 // LinkAt implements vfs.FilesystemImpl.LinkAt.
 func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.VirtualDentry) error {
-	return fs.doCreateAt(rp, false /* dir */, func(parent *dentry, name string) error {
+	return fs.doCreateAt(rp, false /* dir */, func(parentDir *directory, name string) error {
 		if rp.Mount() != vd.Mount() {
 			return syserror.EXDEV
 		}
@@ -226,30 +239,27 @@ func (fs *filesystem) LinkAt(ctx context.Context, rp *vfs.ResolvingPath, vd vfs.
 			return syserror.EMLINK
 		}
 		d.inode.incLinksLocked()
-		child := fs.newDentry(d.inode)
-		parent.vfsd.InsertChild(&child.vfsd, name)
-		parent.inode.impl.(*directory).childList.PushBack(child)
+		parentDir.insertChildLocked(fs.newDentry(d.inode), name)
 		return nil
 	})
 }
 
 // MkdirAt implements vfs.FilesystemImpl.MkdirAt.
 func (fs *filesystem) MkdirAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MkdirOptions) error {
-	return fs.doCreateAt(rp, true /* dir */, func(parent *dentry, name string) error {
-		if parent.inode.nlink == maxLinks {
+	return fs.doCreateAt(rp, true /* dir */, func(parentDir *directory, name string) error {
+		if parentDir.inode.nlink == maxLinks {
 			return syserror.EMLINK
 		}
-		parent.inode.incLinksLocked() // from child's ".."
-		child := fs.newDentry(fs.newDirectory(rp.Credentials(), opts.Mode))
-		parent.vfsd.InsertChild(&child.vfsd, name)
-		parent.inode.impl.(*directory).childList.PushBack(child)
+		parentDir.inode.incLinksLocked() // from child's ".."
+		childDir := fs.newDirectory(rp.Credentials(), opts.Mode)
+		parentDir.insertChildLocked(&childDir.dentry, name)
 		return nil
 	})
 }
 
 // MknodAt implements vfs.FilesystemImpl.MknodAt.
 func (fs *filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts vfs.MknodOptions) error {
-	return fs.doCreateAt(rp, false /* dir */, func(parent *dentry, name string) error {
+	return fs.doCreateAt(rp, false /* dir */, func(parentDir *directory, name string) error {
 		var childInode *inode
 		switch opts.Mode.FileType() {
 		case 0, linux.S_IFREG:
@@ -266,8 +276,7 @@ func (fs *filesystem) MknodAt(ctx context.Context, rp *vfs.ResolvingPath, opts v
 			return syserror.EINVAL
 		}
 		child := fs.newDentry(childInode)
-		parent.vfsd.InsertChild(&child.vfsd, name)
-		parent.inode.impl.(*directory).childList.PushBack(child)
+		parentDir.insertChildLocked(child, name)
 		return nil
 	})
 }
@@ -306,12 +315,12 @@ func (fs *filesystem) OpenAt(ctx context.Context, rp *vfs.ResolvingPath, opts vf
 		return start.open(ctx, rp, &opts, false /* afterCreate */)
 	}
 afterTrailingSymlink:
-	parent, err := walkParentDirLocked(rp, start)
+	parentDir, err := walkParentDirLocked(rp, start)
 	if err != nil {
 		return nil, err
 	}
 	// Check for search permission in the parent directory.
-	if err := parent.inode.checkPermissions(rp.Credentials(), vfs.MayExec); err != nil {
+	if err := parentDir.inode.checkPermissions(rp.Credentials(), vfs.MayExec); err != nil {
 		return nil, err
 	}
 	// Reject attempts to open directories with O_CREAT.
@@ -322,11 +331,14 @@ afterTrailingSymlink:
 	if name == "." || name == ".." {
 		return nil, syserror.EISDIR
 	}
+	if len(name) > linux.NAME_MAX {
+		return nil, syserror.ENAMETOOLONG
+	}
 	// Determine whether or not we need to create a file.
-	child, err := stepLocked(rp, parent)
-	if err == syserror.ENOENT {
+	child, ok := parentDir.childMap[name]
+	if !ok {
 		// Already checked for searchability above; now check for writability.
-		if err := parent.inode.checkPermissions(rp.Credentials(), vfs.MayWrite); err != nil {
+		if err := parentDir.inode.checkPermissions(rp.Credentials(), vfs.MayWrite); err != nil {
 			return nil, err
 		}
 		if err := rp.Mount().CheckBeginWrite(); err != nil {
@@ -335,21 +347,26 @@ afterTrailingSymlink:
 		defer rp.Mount().EndWrite()
 		// Create and open the child.
 		child := fs.newDentry(fs.newRegularFile(rp.Credentials(), opts.Mode))
-		parent.vfsd.InsertChild(&child.vfsd, name)
-		parent.inode.impl.(*directory).childList.PushBack(child)
+		parentDir.insertChildLocked(child, name)
 		fd, err := child.open(ctx, rp, &opts, true)
 		if err != nil {
 			return nil, err
 		}
-		parent.inode.touchCMtime()
+		parentDir.inode.touchCMtime()
 		return fd, nil
 	}
-	if err != nil {
+	// Is the file mounted over?
+	if err := rp.CheckMount(&child.vfsd); err != nil {
 		return nil, err
 	}
 	// Do we need to resolve a trailing symlink?
-	if !rp.Done() {
-		start = parent
+	if symlink, ok := child.inode.impl.(*symlink); ok && rp.ShouldFollowSymlink() {
+		// TODO(gvisor.dev/issue/1197): Symlink traversals updates
+		// access time.
+		if err := rp.HandleSymlink(symlink.target); err != nil {
+			return nil, err
+		}
+		start = &parentDir.dentry
 		goto afterTrailingSymlink
 	}
 	// Open existing file.
@@ -428,7 +445,7 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 	// Resolve newParent first to verify that it's on this Mount.
 	fs.mu.Lock()
 	defer fs.mu.Unlock()
-	newParent, err := walkParentDirLocked(rp, rp.Start().Impl().(*dentry))
+	newParentDir, err := walkParentDirLocked(rp, rp.Start().Impl().(*dentry))
 	if err != nil {
 		return err
 	}
@@ -445,23 +462,22 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 	}
 	defer mnt.EndWrite()
 
-	oldParent := oldParentVD.Dentry().Impl().(*dentry)
-	if err := oldParent.inode.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil {
+	oldParentDir := oldParentVD.Dentry().Impl().(*dentry).inode.impl.(*directory)
+	if err := oldParentDir.inode.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil {
 		return err
 	}
-	// Call vfs.Dentry.Child() instead of stepLocked() or rp.ResolveChild(),
-	// because if the existing child is a symlink or mount point then we want
-	// to rename over it rather than follow it.
-	renamedVFSD := oldParent.vfsd.Child(oldName)
-	if renamedVFSD == nil {
+	renamed, ok := oldParentDir.childMap[oldName]
+	if !ok {
 		return syserror.ENOENT
 	}
-	renamed := renamedVFSD.Impl().(*dentry)
+	// Note that we don't need to call rp.CheckMount(), since if renamed is a
+	// mount point then we want to rename the mount point, not anything in the
+	// mounted filesystem.
 	if renamed.inode.isDir() {
-		if renamed == newParent || renamedVFSD.IsAncestorOf(&newParent.vfsd) {
+		if renamed == &newParentDir.dentry || genericIsAncestorDentry(renamed, &newParentDir.dentry) {
 			return syserror.EINVAL
 		}
-		if oldParent != newParent {
+		if oldParentDir != newParentDir {
 			// Writability is needed to change renamed's "..".
 			if err := renamed.inode.checkPermissions(rp.Credentials(), vfs.MayWrite); err != nil {
 				return err
@@ -473,18 +489,17 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 		}
 	}
 
-	if err := newParent.inode.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil {
+	if err := newParentDir.inode.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil {
 		return err
 	}
-	replacedVFSD := newParent.vfsd.Child(newName)
-	var replaced *dentry
-	if replacedVFSD != nil {
-		replaced = replacedVFSD.Impl().(*dentry)
-		if replaced.inode.isDir() {
+	replaced, ok := newParentDir.childMap[newName]
+	if ok {
+		replacedDir, ok := replaced.inode.impl.(*directory)
+		if ok {
 			if !renamed.inode.isDir() {
 				return syserror.EISDIR
 			}
-			if replaced.vfsd.HasChildren() {
+			if len(replacedDir.childMap) != 0 {
 				return syserror.ENOTEMPTY
 			}
 		} else {
@@ -496,11 +511,13 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 			}
 		}
 	} else {
-		if renamed.inode.isDir() && newParent.inode.nlink == maxLinks {
+		if renamed.inode.isDir() && newParentDir.inode.nlink == maxLinks {
 			return syserror.EMLINK
 		}
 	}
-	if newParent.vfsd.IsDisowned() {
+	// tmpfs never calls VFS.InvalidateDentry(), so newParentDir.dentry can
+	// only be dead if it was deleted.
+	if newParentDir.dentry.vfsd.IsDead() {
 		return syserror.ENOENT
 	}
 
@@ -508,36 +525,38 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 	// simplicity, under the assumption that applications are not intentionally
 	// doing noop renames expecting them to succeed where non-noop renames
 	// would fail.
-	if renamedVFSD == replacedVFSD {
+	if renamed == replaced {
 		return nil
 	}
 	vfsObj := rp.VirtualFilesystem()
-	oldParentDir := oldParent.inode.impl.(*directory)
-	newParentDir := newParent.inode.impl.(*directory)
 	mntns := vfs.MountNamespaceFromContext(ctx)
 	defer mntns.DecRef()
-	if err := vfsObj.PrepareRenameDentry(mntns, renamedVFSD, replacedVFSD); err != nil {
+	var replacedVFSD *vfs.Dentry
+	if replaced != nil {
+		replacedVFSD = &replaced.vfsd
+	}
+	if err := vfsObj.PrepareRenameDentry(mntns, &renamed.vfsd, replacedVFSD); err != nil {
 		return err
 	}
 	if replaced != nil {
-		newParentDir.childList.Remove(replaced)
+		newParentDir.removeChildLocked(replaced)
 		if replaced.inode.isDir() {
-			newParent.inode.decLinksLocked() // from replaced's ".."
+			newParentDir.inode.decLinksLocked() // from replaced's ".."
 		}
 		replaced.inode.decLinksLocked()
 	}
-	oldParentDir.childList.Remove(renamed)
-	newParentDir.childList.PushBack(renamed)
-	if renamed.inode.isDir() {
-		oldParent.inode.decLinksLocked()
-		newParent.inode.incLinksLocked()
+	oldParentDir.removeChildLocked(renamed)
+	newParentDir.insertChildLocked(renamed, newName)
+	vfsObj.CommitRenameReplaceDentry(&renamed.vfsd, replacedVFSD)
+	oldParentDir.inode.touchCMtime()
+	if oldParentDir != newParentDir {
+		if renamed.inode.isDir() {
+			oldParentDir.inode.decLinksLocked()
+			newParentDir.inode.incLinksLocked()
+		}
+		newParentDir.inode.touchCMtime()
 	}
-	oldParent.inode.touchCMtime()
-	newParent.inode.touchCMtime()
 	renamed.inode.touchCtime()
-	// TODO(gvisor.dev/issue/1197): Update timestamps and parent directory
-	// sizes.
-	vfsObj.CommitRenameReplaceDentry(renamedVFSD, &newParent.vfsd, newName, replacedVFSD)
 	return nil
 }
 
@@ -545,11 +564,11 @@ func (fs *filesystem) RenameAt(ctx context.Context, rp *vfs.ResolvingPath, oldPa
 func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error {
 	fs.mu.Lock()
 	defer fs.mu.Unlock()
-	parent, err := walkParentDirLocked(rp, rp.Start().Impl().(*dentry))
+	parentDir, err := walkParentDirLocked(rp, rp.Start().Impl().(*dentry))
 	if err != nil {
 		return err
 	}
-	if err := parent.inode.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil {
+	if err := parentDir.inode.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil {
 		return err
 	}
 	name := rp.Component()
@@ -559,15 +578,15 @@ func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error
 	if name == ".." {
 		return syserror.ENOTEMPTY
 	}
-	childVFSD := parent.vfsd.Child(name)
-	if childVFSD == nil {
+	child, ok := parentDir.childMap[name]
+	if !ok {
 		return syserror.ENOENT
 	}
-	child := childVFSD.Impl().(*dentry)
-	if !child.inode.isDir() {
+	childDir, ok := child.inode.impl.(*directory)
+	if !ok {
 		return syserror.ENOTDIR
 	}
-	if childVFSD.HasChildren() {
+	if len(childDir.childMap) != 0 {
 		return syserror.ENOTEMPTY
 	}
 	mnt := rp.Mount()
@@ -578,14 +597,14 @@ func (fs *filesystem) RmdirAt(ctx context.Context, rp *vfs.ResolvingPath) error
 	vfsObj := rp.VirtualFilesystem()
 	mntns := vfs.MountNamespaceFromContext(ctx)
 	defer mntns.DecRef()
-	if err := vfsObj.PrepareDeleteDentry(mntns, childVFSD); err != nil {
+	if err := vfsObj.PrepareDeleteDentry(mntns, &child.vfsd); err != nil {
 		return err
 	}
-	parent.inode.impl.(*directory).childList.Remove(child)
-	parent.inode.decLinksLocked() // from child's ".."
+	parentDir.removeChildLocked(child)
+	parentDir.inode.decLinksLocked() // from child's ".."
 	child.inode.decLinksLocked()
-	vfsObj.CommitDeleteDentry(childVFSD)
-	parent.inode.touchCMtime()
+	vfsObj.CommitDeleteDentry(&child.vfsd)
+	parentDir.inode.touchCMtime()
 	return nil
 }
 
@@ -627,10 +646,9 @@ func (fs *filesystem) StatFSAt(ctx context.Context, rp *vfs.ResolvingPath) (linu
 
 // SymlinkAt implements vfs.FilesystemImpl.SymlinkAt.
 func (fs *filesystem) SymlinkAt(ctx context.Context, rp *vfs.ResolvingPath, target string) error {
-	return fs.doCreateAt(rp, false /* dir */, func(parent *dentry, name string) error {
+	return fs.doCreateAt(rp, false /* dir */, func(parentDir *directory, name string) error {
 		child := fs.newDentry(fs.newSymlink(rp.Credentials(), target))
-		parent.vfsd.InsertChild(&child.vfsd, name)
-		parent.inode.impl.(*directory).childList.PushBack(child)
+		parentDir.insertChildLocked(child, name)
 		return nil
 	})
 }
@@ -639,22 +657,21 @@ func (fs *filesystem) SymlinkAt(ctx context.Context, rp *vfs.ResolvingPath, targ
 func (fs *filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error {
 	fs.mu.Lock()
 	defer fs.mu.Unlock()
-	parent, err := walkParentDirLocked(rp, rp.Start().Impl().(*dentry))
+	parentDir, err := walkParentDirLocked(rp, rp.Start().Impl().(*dentry))
 	if err != nil {
 		return err
 	}
-	if err := parent.inode.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil {
+	if err := parentDir.inode.checkPermissions(rp.Credentials(), vfs.MayWrite|vfs.MayExec); err != nil {
 		return err
 	}
 	name := rp.Component()
 	if name == "." || name == ".." {
 		return syserror.EISDIR
 	}
-	childVFSD := parent.vfsd.Child(name)
-	if childVFSD == nil {
+	child, ok := parentDir.childMap[name]
+	if !ok {
 		return syserror.ENOENT
 	}
-	child := childVFSD.Impl().(*dentry)
 	if child.inode.isDir() {
 		return syserror.EISDIR
 	}
@@ -669,13 +686,13 @@ func (fs *filesystem) UnlinkAt(ctx context.Context, rp *vfs.ResolvingPath) error
 	vfsObj := rp.VirtualFilesystem()
 	mntns := vfs.MountNamespaceFromContext(ctx)
 	defer mntns.DecRef()
-	if err := vfsObj.PrepareDeleteDentry(mntns, childVFSD); err != nil {
+	if err := vfsObj.PrepareDeleteDentry(mntns, &child.vfsd); err != nil {
 		return err
 	}
-	parent.inode.impl.(*directory).childList.Remove(child)
+	parentDir.removeChildLocked(child)
 	child.inode.decLinksLocked()
-	vfsObj.CommitDeleteDentry(childVFSD)
-	parent.inode.touchCMtime()
+	vfsObj.CommitDeleteDentry(&child.vfsd)
+	parentDir.inode.touchCMtime()
 	return nil
 }
 
@@ -743,5 +760,5 @@ func (fs *filesystem) RemovexattrAt(ctx context.Context, rp *vfs.ResolvingPath,
 func (fs *filesystem) PrependPath(ctx context.Context, vfsroot, vd vfs.VirtualDentry, b *fspath.Builder) error {
 	fs.mu.RLock()
 	defer fs.mu.RUnlock()
-	return vfs.GenericPrependPath(vfsroot, vd, b)
+	return genericPrependPath(vfsroot, vd.Mount(), vd.Dentry().Impl().(*dentry), b)
 }
diff --git a/pkg/sentry/fsimpl/tmpfs/fstree.go b/pkg/sentry/fsimpl/tmpfs/fstree.go
new file mode 100755
index 000000000..fab366345
--- /dev/null
+++ b/pkg/sentry/fsimpl/tmpfs/fstree.go
@@ -0,0 +1,45 @@
+package tmpfs
+
+import (
+	"gvisor.dev/gvisor/pkg/fspath"
+	"gvisor.dev/gvisor/pkg/sentry/vfs"
+)
+
+// IsAncestorDentry returns true if d is an ancestor of d2; that is, d is
+// either d2's parent or an ancestor of d2's parent.
+func genericIsAncestorDentry(d, d2 *dentry) bool {
+	for {
+		if d2.parent == d {
+			return true
+		}
+		if d2.parent == d2 {
+			return false
+		}
+		d2 = d2.parent
+	}
+}
+
+// ParentOrSelf returns d.parent. If d.parent is nil, ParentOrSelf returns d.
+func genericParentOrSelf(d *dentry) *dentry {
+	if d.parent != nil {
+		return d.parent
+	}
+	return d
+}
+
+// PrependPath is a generic implementation of FilesystemImpl.PrependPath().
+func genericPrependPath(vfsroot vfs.VirtualDentry, mnt *vfs.Mount, d *dentry, b *fspath.Builder) error {
+	for {
+		if mnt == vfsroot.Mount() && &d.vfsd == vfsroot.Dentry() {
+			return vfs.PrependPathAtVFSRootError{}
+		}
+		if &d.vfsd == mnt.Root() {
+			return nil
+		}
+		if d.parent == nil {
+			return vfs.PrependPathAtNonMountRootError{}
+		}
+		b.PrependComponent(d.name)
+		d = d.parent
+	}
+}
diff --git a/pkg/sentry/fsimpl/tmpfs/tmpfs.go b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
index 82c709b43..efc931468 100755
--- a/pkg/sentry/fsimpl/tmpfs/tmpfs.go
+++ b/pkg/sentry/fsimpl/tmpfs/tmpfs.go
@@ -12,16 +12,19 @@
 // See the License for the specific language governing permissions and
 // limitations under the License.
 
-// Package tmpfs provides a filesystem implementation that behaves like tmpfs:
-// the Dentry tree is the sole source of truth for the state of the filesystem.
+// Package tmpfs provides an in-memory filesystem whose contents are
+// application-mutable, consistent with Linux's tmpfs.
 //
 // Lock order:
 //
 // filesystem.mu
 //   inode.mu
 //     regularFileFD.offMu
+//       *** "memmap.Mappable locks" below this point
 //       regularFile.mapsMu
+//         *** "memmap.Mappable locks taken by Translate" below this point
 //         regularFile.dataMu
+//     directory.iterMu
 package tmpfs
 
 import (
@@ -41,6 +44,7 @@ import (
 	"gvisor.dev/gvisor/pkg/sentry/vfs/memxattr"
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/syserror"
+	"gvisor.dev/gvisor/pkg/usermem"
 )
 
 // Name is the default filesystem name.
@@ -112,18 +116,18 @@ func (fstype FilesystemType) GetFilesystem(ctx context.Context, vfsObj *vfs.Virt
 
 	fs.vfsfs.Init(vfsObj, newFSType, &fs)
 
-	var root *inode
+	var root *dentry
 	switch rootFileType {
 	case linux.S_IFREG:
-		root = fs.newRegularFile(creds, 0777)
+		root = fs.newDentry(fs.newRegularFile(creds, 0777))
 	case linux.S_IFLNK:
-		root = fs.newSymlink(creds, tmpfsOpts.RootSymlinkTarget)
+		root = fs.newDentry(fs.newSymlink(creds, tmpfsOpts.RootSymlinkTarget))
 	case linux.S_IFDIR:
-		root = fs.newDirectory(creds, 01777)
+		root = &fs.newDirectory(creds, 01777).dentry
 	default:
 		return nil, nil, fmt.Errorf("invalid tmpfs root file type: %#o", rootFileType)
 	}
-	return &fs.vfsfs, &fs.newDentry(root).vfsd, nil
+	return &fs.vfsfs, &root.vfsd, nil
 }
 
 // Release implements vfs.FilesystemImpl.Release.
@@ -134,20 +138,29 @@ func (fs *filesystem) Release() {
 type dentry struct {
 	vfsd vfs.Dentry
 
+	// parent is this dentry's parent directory. Each referenced dentry holds a
+	// reference on parent.dentry. If this dentry is a filesystem root, parent
+	// is nil. parent is protected by filesystem.mu.
+	parent *dentry
+
+	// name is the name of this dentry in its parent. If this dentry is a
+	// filesystem root, name is the empty string. name is protected by
+	// filesystem.mu.
+	name string
+
+	// dentryEntry (ugh) links dentries into their parent directory.childList.
+	dentryEntry
+
 	// inode is the inode represented by this dentry. Multiple Dentries may
 	// share a single non-directory inode (with hard links). inode is
 	// immutable.
-	inode *inode
-
+	//
 	// tmpfs doesn't count references on dentries; because the dentry tree is
 	// the sole source of truth, it is by definition always consistent with the
 	// state of the filesystem. However, it does count references on inodes,
 	// because inode resources are released when all references are dropped.
-	// (tmpfs doesn't really have resources to release, but we implement
-	// reference counting because tmpfs regular files will.)
-
-	// dentryEntry (ugh) links dentries into their parent directory.childList.
-	dentryEntry
+	// dentry therefore forwards reference counting directly to inode.
+	inode *inode
 }
 
 func (fs *filesystem) newDentry(inode *inode) *dentry {
@@ -207,10 +220,6 @@ type inode struct {
 	ctime int64 // nanoseconds
 	mtime int64 // nanoseconds
 
-	// Only meaningful for device special files.
-	rdevMajor uint32
-	rdevMinor uint32
-
 	// Advisory file locks, which lock at the inode level.
 	locks lock.FileLocks
 
@@ -230,7 +239,7 @@ func (i *inode) init(impl interface{}, fs *filesystem, creds *auth.Credentials,
 	i.gid = uint32(creds.EffectiveKGID)
 	i.ino = atomic.AddUint64(&fs.nextInoMinusOne, 1)
 	// Tmpfs creation sets atime, ctime, and mtime to current time.
-	now := i.clock.Now().Nanoseconds()
+	now := fs.clock.Now().Nanoseconds()
 	i.atime = now
 	i.ctime = now
 	i.mtime = now
@@ -283,14 +292,10 @@ func (i *inode) tryIncRef() bool {
 func (i *inode) decRef() {
 	if refs := atomic.AddInt64(&i.refs, -1); refs == 0 {
 		if regFile, ok := i.impl.(*regularFile); ok {
-			// Hold inode.mu and regFile.dataMu while mutating
-			// size.
-			i.mu.Lock()
-			regFile.dataMu.Lock()
+			// Release memory used by regFile to store data. Since regFile is
+			// no longer usable, we don't need to grab any locks or update any
+			// metadata.
 			regFile.data.DropAll(regFile.memFile)
-			atomic.StoreUint64(&regFile.size, 0)
-			regFile.dataMu.Unlock()
-			i.mu.Unlock()
 		}
 	} else if refs < 0 {
 		panic("tmpfs.inode.decRef() called without holding a reference")
@@ -310,15 +315,15 @@ func (i *inode) checkPermissions(creds *auth.Credentials, ats vfs.AccessTypes) e
 // a concurrent modification), so we do not require holding inode.mu.
 func (i *inode) statTo(stat *linux.Statx) {
 	stat.Mask = linux.STATX_TYPE | linux.STATX_MODE | linux.STATX_NLINK |
-		linux.STATX_UID | linux.STATX_GID | linux.STATX_INO | linux.STATX_ATIME |
-		linux.STATX_BTIME | linux.STATX_CTIME | linux.STATX_MTIME
-	stat.Blksize = 1 // usermem.PageSize in tmpfs
+		linux.STATX_UID | linux.STATX_GID | linux.STATX_INO | linux.STATX_SIZE |
+		linux.STATX_BLOCKS | linux.STATX_ATIME | linux.STATX_CTIME |
+		linux.STATX_MTIME
+	stat.Blksize = usermem.PageSize
 	stat.Nlink = atomic.LoadUint32(&i.nlink)
 	stat.UID = atomic.LoadUint32(&i.uid)
 	stat.GID = atomic.LoadUint32(&i.gid)
 	stat.Mode = uint16(atomic.LoadUint32(&i.mode))
 	stat.Ino = i.ino
-	// Linux's tmpfs has no concept of btime, so zero-value is returned.
 	stat.Atime = linux.NsecToStatxTimestamp(i.atime)
 	stat.Ctime = linux.NsecToStatxTimestamp(i.ctime)
 	stat.Mtime = linux.NsecToStatxTimestamp(i.mtime)
@@ -327,19 +332,22 @@ func (i *inode) statTo(stat *linux.Statx) {
 	case *regularFile:
 		stat.Mask |= linux.STATX_SIZE | linux.STATX_BLOCKS
 		stat.Size = uint64(atomic.LoadUint64(&impl.size))
-		// In tmpfs, this will be FileRangeSet.Span() / 512 (but also cached in
-		// a uint64 accessed using atomic memory operations to avoid taking
-		// locks).
+		// TODO(jamieliu): This should be impl.data.Span() / 512, but this is
+		// too expensive to compute here. Cache it in regularFile.
 		stat.Blocks = allocatedBlocksForSize(stat.Size)
+	case *directory:
+		// "20" is mm/shmem.c:BOGO_DIRENT_SIZE.
+		stat.Size = 20 * (2 + uint64(atomic.LoadInt64(&impl.numChildren)))
+		// stat.Blocks is 0.
 	case *symlink:
-		stat.Mask |= linux.STATX_SIZE | linux.STATX_BLOCKS
 		stat.Size = uint64(len(impl.target))
-		stat.Blocks = allocatedBlocksForSize(stat.Size)
+		// stat.Blocks is 0.
+	case *namedPipe, *socketFile:
+		// stat.Size and stat.Blocks are 0.
 	case *deviceFile:
+		// stat.Size and stat.Blocks are 0.
 		stat.RdevMajor = impl.major
 		stat.RdevMinor = impl.minor
-	case *socketFile, *directory, *namedPipe:
-		// Nothing to do.
 	default:
 		panic(fmt.Sprintf("unknown inode type: %T", i.impl))
 	}
diff --git a/pkg/sentry/vfs/dentry.go b/pkg/sentry/vfs/dentry.go
index 35b208721..8624dbd5d 100755
--- a/pkg/sentry/vfs/dentry.go
+++ b/pkg/sentry/vfs/dentry.go
@@ -15,34 +15,17 @@
 package vfs
 
 import (
-	"fmt"
 	"sync/atomic"
 
 	"gvisor.dev/gvisor/pkg/sync"
 	"gvisor.dev/gvisor/pkg/syserror"
 )
 
-// Dentry represents a node in a Filesystem tree which may represent a file.
+// Dentry represents a node in a Filesystem tree at which a file exists.
 //
 // Dentries are reference-counted. Unless otherwise specified, all Dentry
 // methods require that a reference is held.
 //
-// A Dentry transitions through up to 3 different states through its lifetime:
-//
-// - Dentries are initially "independent". Independent Dentries have no parent,
-// and consequently no name.
-//
-// - Dentry.InsertChild() causes an independent Dentry to become a "child" of
-// another Dentry. A child node has a parent node, and a name in that parent,
-// both of which are mutable by DentryMoveChild(). Each child Dentry's name is
-// unique within its parent.
-//
-// - Dentry.RemoveChild() causes a child Dentry to become "disowned". A
-// disowned Dentry can still refer to its former parent and its former name in
-// said parent, but the disowned Dentry is no longer reachable from its parent,
-// and a new Dentry with the same name may become a child of the parent. (This
-// is analogous to a struct dentry being "unhashed" in Linux.)
-//
 // Dentry is loosely analogous to Linux's struct dentry, but:
 //
 // - VFS does not associate Dentries with inodes. gVisor interacts primarily
@@ -57,9 +40,6 @@ import (
 // and/or FileDescriptionImpl methods in gVisor's VFS. Filesystems that do
 // support inodes may store appropriate state in implementations of DentryImpl.
 //
-// - VFS does not provide synchronization for mutable Dentry fields, other than
-// mount-related ones.
-//
 // - VFS does not require that Dentries are instantiated for all paths accessed
 // through VFS, only those that are tracked beyond the scope of a single
 // Filesystem operation. This includes file descriptions, mount points, mount
@@ -67,6 +47,10 @@ import (
 // of Dentries for operations on mutable remote filesystems that can't actually
 // cache any state in the Dentry.
 //
+// - VFS does not track filesystem structure (i.e. relationships between
+// Dentries), since both the relevant state and synchronization are
+// filesystem-specific.
+//
 // - For the reasons above, VFS is not directly responsible for managing Dentry
 // lifetime. Dentry reference counts only indicate the extent to which VFS
 // requires Dentries to exist; Filesystems may elect to cache or discard
@@ -74,36 +58,23 @@ import (
 //
 // +stateify savable
 type Dentry struct {
-	// parent is this Dentry's parent in this Filesystem. If this Dentry is
-	// independent, parent is nil.
-	parent *Dentry
-
-	// name is this Dentry's name in parent.
-	name string
+	// mu synchronizes deletion/invalidation and mounting over this Dentry.
+	mu sync.Mutex `state:"nosave"`
 
-	flags uint32
+	// dead is true if the file represented by this Dentry has been deleted (by
+	// CommitDeleteDentry or CommitRenameReplaceDentry) or invalidated (by
+	// InvalidateDentry). dead is protected by mu.
+	dead bool
 
 	// mounts is the number of Mounts for which this Dentry is Mount.point.
 	// mounts is accessed using atomic memory operations.
 	mounts uint32
 
-	// children are child Dentries.
-	children map[string]*Dentry
-
-	// mu synchronizes disowning and mounting over this Dentry.
-	mu sync.Mutex `state:"nosave"`
-
 	// impl is the DentryImpl associated with this Dentry. impl is immutable.
 	// This should be the last field in Dentry.
 	impl DentryImpl
 }
 
-const (
-	// dflagsDisownedMask is set in Dentry.flags if the Dentry has been
-	// disowned.
-	dflagsDisownedMask = 1 << iota
-)
-
 // Init must be called before first use of d.
 func (d *Dentry) Init(impl DentryImpl) {
 	d.impl = impl
@@ -134,20 +105,6 @@ type DentryImpl interface {
 	DecRef()
 }
 
-// IsDisowned returns true if d is disowned.
-func (d *Dentry) IsDisowned() bool {
-	return atomic.LoadUint32(&d.flags)&dflagsDisownedMask != 0
-}
-
-// Preconditions: !d.IsDisowned().
-func (d *Dentry) setDisowned() {
-	atomic.AddUint32(&d.flags, dflagsDisownedMask)
-}
-
-func (d *Dentry) isMounted() bool {
-	return atomic.LoadUint32(&d.mounts) != 0
-}
-
 // IncRef increments d's reference count.
 func (d *Dentry) IncRef() {
 	d.impl.IncRef()
@@ -164,104 +121,26 @@ func (d *Dentry) DecRef() {
 	d.impl.DecRef()
 }
 
-// These functions are exported so that filesystem implementations can use
-// them. The vfs package, and users of VFS, should not call these functions.
-// Unless otherwise specified, these methods require that there are no
-// concurrent mutators of d.
-
-// Name returns d's name in its parent in its owning Filesystem. If d is
-// independent, Name returns an empty string.
-func (d *Dentry) Name() string {
-	return d.name
-}
-
-// Parent returns d's parent in its owning Filesystem. It does not take a
-// reference on the returned Dentry. If d is independent, Parent returns nil.
-func (d *Dentry) Parent() *Dentry {
-	return d.parent
-}
-
-// ParentOrSelf is equivalent to Parent, but returns d if d is independent.
-func (d *Dentry) ParentOrSelf() *Dentry {
-	if d.parent == nil {
-		return d
-	}
-	return d.parent
-}
-
-// Child returns d's child with the given name in its owning Filesystem. It
-// does not take a reference on the returned Dentry. If no such child exists,
-// Child returns nil.
-func (d *Dentry) Child(name string) *Dentry {
-	return d.children[name]
-}
-
-// HasChildren returns true if d has any children.
-func (d *Dentry) HasChildren() bool {
-	return len(d.children) != 0
-}
-
-// Children returns a map containing all of d's children.
-func (d *Dentry) Children() map[string]*Dentry {
-	if !d.HasChildren() {
-		return nil
-	}
-	m := make(map[string]*Dentry)
-	for name, child := range d.children {
-		m[name] = child
-	}
-	return m
+// IsDead returns true if d has been deleted or invalidated by its owning
+// filesystem.
+func (d *Dentry) IsDead() bool {
+	d.mu.Lock()
+	defer d.mu.Unlock()
+	return d.dead
 }
 
-// InsertChild makes child a child of d with the given name.
-//
-// InsertChild is a mutator of d and child.
-//
-// Preconditions: child must be an independent Dentry. d and child must be from
-// the same Filesystem. d must not already have a child with the given name.
-func (d *Dentry) InsertChild(child *Dentry, name string) {
-	if checkInvariants {
-		if _, ok := d.children[name]; ok {
-			panic(fmt.Sprintf("parent already contains a child named %q", name))
-		}
-		if child.parent != nil || child.name != "" {
-			panic(fmt.Sprintf("child is not independent: parent = %v, name = %q", child.parent, child.name))
-		}
-	}
-	if d.children == nil {
-		d.children = make(map[string]*Dentry)
-	}
-	d.children[name] = child
-	child.parent = d
-	child.name = name
+func (d *Dentry) isMounted() bool {
+	return atomic.LoadUint32(&d.mounts) != 0
 }
 
-// IsAncestorOf returns true if d is an ancestor of d2; that is, d is either
-// d2's parent or an ancestor of d2's parent.
-func (d *Dentry) IsAncestorOf(d2 *Dentry) bool {
-	for d2.parent != nil {
-		if d2.parent == d {
-			return true
-		}
-		d2 = d2.parent
-	}
-	return false
-}
+// The following functions are exported so that filesystem implementations can
+// use them. The vfs package, and users of VFS, should not call these
+// functions.
 
 // PrepareDeleteDentry must be called before attempting to delete the file
 // represented by d. If PrepareDeleteDentry succeeds, the caller must call
 // AbortDeleteDentry or CommitDeleteDentry depending on the deletion's outcome.
-//
-// Preconditions: d is a child Dentry.
 func (vfs *VirtualFilesystem) PrepareDeleteDentry(mntns *MountNamespace, d *Dentry) error {
-	if checkInvariants {
-		if d.parent == nil {
-			panic("d is independent")
-		}
-		if d.IsDisowned() {
-			panic("d is already disowned")
-		}
-	}
 	vfs.mountMu.Lock()
 	if mntns.mountpoints[d] != 0 {
 		vfs.mountMu.Unlock()
@@ -280,42 +159,27 @@ func (vfs *VirtualFilesystem) AbortDeleteDentry(d *Dentry) {
 	d.mu.Unlock()
 }
 
-// CommitDeleteDentry must be called after the file represented by d is
-// deleted, and causes d to become disowned.
-//
-// CommitDeleteDentry is a mutator of d and d.Parent().
-//
-// Preconditions: PrepareDeleteDentry was previously called on d.
+// CommitDeleteDentry must be called after PrepareDeleteDentry if the deletion
+// succeeds.
 func (vfs *VirtualFilesystem) CommitDeleteDentry(d *Dentry) {
-	if d.parent != nil {
-		delete(d.parent.children, d.name)
-	}
-	d.setDisowned()
+	d.dead = true
 	d.mu.Unlock()
 	if d.isMounted() {
-		vfs.forgetDisownedMountpoint(d)
+		vfs.forgetDeadMountpoint(d)
 	}
 }
 
-// ForceDeleteDentry causes d to become disowned. It should only be used in
-// cases where VFS has no ability to stop the deletion (e.g. d represents the
-// local state of a file on a remote filesystem on which the file has already
-// been deleted).
-//
-// ForceDeleteDentry is a mutator of d and d.Parent().
-//
-// Preconditions: d is a child Dentry.
-func (vfs *VirtualFilesystem) ForceDeleteDentry(d *Dentry) {
-	if checkInvariants {
-		if d.parent == nil {
-			panic("d is independent")
-		}
-		if d.IsDisowned() {
-			panic("d is already disowned")
-		}
-	}
+// InvalidateDentry is called when d ceases to represent the file it formerly
+// did for reasons outside of VFS' control (e.g. d represents the local state
+// of a file on a remote filesystem on which the file has already been
+// deleted).
+func (vfs *VirtualFilesystem) InvalidateDentry(d *Dentry) {
 	d.mu.Lock()
-	vfs.CommitDeleteDentry(d)
+	d.dead = true
+	d.mu.Unlock()
+	if d.isMounted() {
+		vfs.forgetDeadMountpoint(d)
+	}
 }
 
 // PrepareRenameDentry must be called before attempting to rename the file
@@ -324,25 +188,9 @@ func (vfs *VirtualFilesystem) ForceDeleteDentry(d *Dentry) {
 // caller must call AbortRenameDentry, CommitRenameReplaceDentry, or
 // CommitRenameExchangeDentry depending on the rename's outcome.
 //
-// Preconditions: from is a child Dentry. If to is not nil, it must be a child
-// Dentry from the same Filesystem. from != to.
+// Preconditions: If to is not nil, it must be a child Dentry from the same
+// Filesystem. from != to.
 func (vfs *VirtualFilesystem) PrepareRenameDentry(mntns *MountNamespace, from, to *Dentry) error {
-	if checkInvariants {
-		if from.parent == nil {
-			panic("from is independent")
-		}
-		if from.IsDisowned() {
-			panic("from is already disowned")
-		}
-		if to != nil {
-			if to.parent == nil {
-				panic("to is independent")
-			}
-			if to.IsDisowned() {
-				panic("to is already disowned")
-			}
-		}
-	}
 	vfs.mountMu.Lock()
 	if mntns.mountpoints[from] != 0 {
 		vfs.mountMu.Unlock()
@@ -376,24 +224,14 @@ func (vfs *VirtualFilesystem) AbortRenameDentry(from, to *Dentry) {
 // is renamed without RENAME_EXCHANGE. If to is not nil, it represents the file
 // that was replaced by from.
 //
-// CommitRenameReplaceDentry is a mutator of from, to, from.Parent(), and
-// to.Parent().
-//
 // Preconditions: PrepareRenameDentry was previously called on from and to.
-// newParent.Child(newName) == to.
-func (vfs *VirtualFilesystem) CommitRenameReplaceDentry(from, newParent *Dentry, newName string, to *Dentry) {
-	if newParent.children == nil {
-		newParent.children = make(map[string]*Dentry)
-	}
-	newParent.children[newName] = from
-	from.parent = newParent
-	from.name = newName
+func (vfs *VirtualFilesystem) CommitRenameReplaceDentry(from, to *Dentry) {
 	from.mu.Unlock()
 	if to != nil {
-		to.setDisowned()
+		to.dead = true
 		to.mu.Unlock()
 		if to.isMounted() {
-			vfs.forgetDisownedMountpoint(to)
+			vfs.forgetDeadMountpoint(to)
 		}
 	}
 }
@@ -401,25 +239,18 @@ func (vfs *VirtualFilesystem) CommitRenameReplaceDentry(from, newParent *Dentry,
 // CommitRenameExchangeDentry must be called after the files represented by
 // from and to are exchanged by rename(RENAME_EXCHANGE).
 //
-// CommitRenameExchangeDentry is a mutator of from, to, from.Parent(), and
-// to.Parent().
-//
 // Preconditions: PrepareRenameDentry was previously called on from and to.
 func (vfs *VirtualFilesystem) CommitRenameExchangeDentry(from, to *Dentry) {
-	from.parent, to.parent = to.parent, from.parent
-	from.name, to.name = to.name, from.name
-	from.parent.children[from.name] = from
-	to.parent.children[to.name] = to
 	from.mu.Unlock()
 	to.mu.Unlock()
 }
 
-// forgetDisownedMountpoint is called when a mount point is deleted to umount
-// all mounts using it in all other mount namespaces.
+// forgetDeadMountpoint is called when a mount point is deleted or invalidated
+// to umount all mounts using it in all other mount namespaces.
 //
-// forgetDisownedMountpoint is analogous to Linux's
+// forgetDeadMountpoint is analogous to Linux's
 // fs/namespace.c:__detach_mounts().
-func (vfs *VirtualFilesystem) forgetDisownedMountpoint(d *Dentry) {
+func (vfs *VirtualFilesystem) forgetDeadMountpoint(d *Dentry) {
 	var (
 		vdsToDecRef    []VirtualDentry
 		mountsToDecRef []*Mount
diff --git a/pkg/sentry/vfs/file_description.go b/pkg/sentry/vfs/file_description.go
index 5976b5ccd..15cc091e2 100755
--- a/pkg/sentry/vfs/file_description.go
+++ b/pkg/sentry/vfs/file_description.go
@@ -127,7 +127,8 @@ func (fd *FileDescription) Init(impl FileDescriptionImpl, statusFlags uint32, mn
 		mount:  mnt,
 		dentry: d,
 	}
-	fd.vd.IncRef()
+	mnt.IncRef()
+	d.IncRef()
 	fd.opts = *opts
 	fd.readable = MayReadFileWithOpenFlags(statusFlags)
 	fd.writable = writable
diff --git a/pkg/sentry/vfs/filesystem.go b/pkg/sentry/vfs/filesystem.go
index a537a29d1..74577bc2f 100755
--- a/pkg/sentry/vfs/filesystem.go
+++ b/pkg/sentry/vfs/filesystem.go
@@ -346,7 +346,10 @@ type FilesystemImpl interface {
 	// ENOTEMPTY.
 	//
 	// Preconditions: !rp.Done(). For the final path component in rp,
-	// !rp.ShouldFollowSymlink(). oldName is not "." or "..".
+	// !rp.ShouldFollowSymlink(). oldParentVD.Dentry() was obtained from a
+	// previous call to
+	// oldParentVD.Mount().Filesystem().Impl().GetParentDentryAt(). oldName is
+	// not "." or "..".
 	//
 	// Postconditions: If RenameAt returns an error returned by
 	// ResolvingPath.Resolve*(), then !rp.Done().
diff --git a/pkg/sentry/vfs/filesystem_impl_util.go b/pkg/sentry/vfs/filesystem_impl_util.go
index 7315a588e..465e610e0 100755
--- a/pkg/sentry/vfs/filesystem_impl_util.go
+++ b/pkg/sentry/vfs/filesystem_impl_util.go
@@ -16,8 +16,6 @@ package vfs
 
 import (
 	"strings"
-
-	"gvisor.dev/gvisor/pkg/fspath"
 )
 
 // GenericParseMountOptions parses a comma-separated list of options of the
@@ -43,27 +41,3 @@ func GenericParseMountOptions(str string) map[string]string {
 	}
 	return m
 }
-
-// GenericPrependPath may be used by implementations of
-// FilesystemImpl.PrependPath() for which a single statically-determined lock
-// or set of locks is sufficient to ensure its preconditions (as opposed to
-// e.g. per-Dentry locks).
-//
-// Preconditions: Dentry.Name() and Dentry.Parent() must be held constant for
-// vd.Dentry() and all of its ancestors.
-func GenericPrependPath(vfsroot, vd VirtualDentry, b *fspath.Builder) error {
-	mnt, d := vd.mount, vd.dentry
-	for {
-		if mnt == vfsroot.mount && d == vfsroot.dentry {
-			return PrependPathAtVFSRootError{}
-		}
-		if d == mnt.root {
-			return nil
-		}
-		if d.parent == nil {
-			return PrependPathAtNonMountRootError{}
-		}
-		b.PrependComponent(d.name)
-		d = d.parent
-	}
-}
diff --git a/pkg/sentry/vfs/mount.go b/pkg/sentry/vfs/mount.go
index f06946103..02850b65c 100755
--- a/pkg/sentry/vfs/mount.go
+++ b/pkg/sentry/vfs/mount.go
@@ -188,6 +188,7 @@ func (vfs *VirtualFilesystem) MountAt(ctx context.Context, creds *auth.Credentia
 	if err != nil {
 		return err
 	}
+
 	// We can't hold vfs.mountMu while calling FilesystemImpl methods due to
 	// lock ordering.
 	vd, err := vfs.GetDentryAt(ctx, creds, target, &GetDentryOptions{})
@@ -199,7 +200,7 @@ func (vfs *VirtualFilesystem) MountAt(ctx context.Context, creds *auth.Credentia
 	vfs.mountMu.Lock()
 	vd.dentry.mu.Lock()
 	for {
-		if vd.dentry.IsDisowned() {
+		if vd.dentry.dead {
 			vd.dentry.mu.Unlock()
 			vfs.mountMu.Unlock()
 			vd.DecRef()
@@ -665,6 +666,12 @@ func (mnt *Mount) submountsLocked() []*Mount {
 	return mounts
 }
 
+// Root returns the mount's root. It does not take a reference on the returned
+// Dentry.
+func (mnt *Mount) Root() *Dentry {
+	return mnt.root
+}
+
 // Root returns mntns' root. A reference is taken on the returned
 // VirtualDentry.
 func (mntns *MountNamespace) Root() VirtualDentry {
diff --git a/pkg/sentry/vfs/pathname.go b/pkg/sentry/vfs/pathname.go
index f21a88034..cd78d66bc 100755
--- a/pkg/sentry/vfs/pathname.go
+++ b/pkg/sentry/vfs/pathname.go
@@ -58,7 +58,7 @@ loop:
 		switch err.(type) {
 		case nil:
 			if vd.mount == vfsroot.mount && vd.mount.root == vfsroot.dentry {
-				// GenericPrependPath() will have returned
+				// genericfstree.PrependPath() will have returned
 				// PrependPathAtVFSRootError in this case since it checks
 				// against vfsroot before mnt.root, but other implementations
 				// of FilesystemImpl.PrependPath() may return nil instead.
@@ -84,7 +84,7 @@ loop:
 		}
 	}
 	b.PrependByte('/')
-	if origD.IsDisowned() {
+	if origD.IsDead() {
 		b.AppendString(" (deleted)")
 	}
 	return b.String(), nil
@@ -136,7 +136,7 @@ loop:
 // PathnameForGetcwd returns an absolute pathname to vd, consistent with
 // Linux's sys_getcwd().
 func (vfs *VirtualFilesystem) PathnameForGetcwd(ctx context.Context, vfsroot, vd VirtualDentry) (string, error) {
-	if vd.dentry.IsDisowned() {
+	if vd.dentry.IsDead() {
 		return "", syserror.ENOENT
 	}
 
diff --git a/pkg/sentry/vfs/resolving_path.go b/pkg/sentry/vfs/resolving_path.go
index 8f31495da..9d047ff88 100755
--- a/pkg/sentry/vfs/resolving_path.go
+++ b/pkg/sentry/vfs/resolving_path.go
@@ -29,7 +29,9 @@ import (
 //
 // From the perspective of FilesystemImpl methods, a ResolvingPath represents a
 // starting Dentry on the associated Filesystem (on which a reference is
-// already held) and a stream of path components relative to that Dentry.
+// already held), a stream of path components relative to that Dentry, and
+// elements of the invoking Context that are commonly required by
+// FilesystemImpl methods.
 //
 // ResolvingPath is loosely analogous to Linux's struct nameidata.
 type ResolvingPath struct {
@@ -251,18 +253,17 @@ func (rp *ResolvingPath) relpathCommit() {
 	rp.origParts[rp.curPart] = rp.pit
 }
 
-// ResolveParent returns the VFS parent of d. It does not take a reference on
-// the returned Dentry.
-//
-// Preconditions: There are no concurrent mutators of d.
-//
-// Postconditions: If the returned error is nil, then the returned Dentry is
-// not nil.
-func (rp *ResolvingPath) ResolveParent(d *Dentry) (*Dentry, error) {
-	var parent *Dentry
+// CheckRoot is called before resolving the parent of the Dentry d. If the
+// Dentry is contextually a VFS root, such that path resolution should treat
+// d's parent as itself, CheckRoot returns (true, nil). If the Dentry is the
+// root of a non-root mount, such that path resolution should switch to another
+// Mount, CheckRoot returns (unspecified, non-nil error). Otherwise, path
+// resolution should resolve d's parent normally, and CheckRoot returns (false,
+// nil).
+func (rp *ResolvingPath) CheckRoot(d *Dentry) (bool, error) {
 	if d == rp.root.dentry && rp.mount == rp.root.mount {
-		// At contextual VFS root.
-		parent = d
+		// At contextual VFS root (due to e.g. chroot(2)).
+		return true, nil
 	} else if d == rp.mount.root {
 		// At mount root ...
 		vd := rp.vfs.getMountpointAt(rp.mount, rp.root)
@@ -270,59 +271,27 @@ func (rp *ResolvingPath) ResolveParent(d *Dentry) (*Dentry, error) {
 			// ... of non-root mount.
 			rp.nextMount = vd.mount
 			rp.nextStart = vd.dentry
-			return nil, resolveMountRootOrJumpError{}
+			return false, resolveMountRootOrJumpError{}
 		}
 		// ... of root mount.
-		parent = d
-	} else if d.parent == nil {
-		// At filesystem root.
-		parent = d
-	} else {
-		parent = d.parent
+		return true, nil
 	}
-	if parent.isMounted() {
-		if mnt := rp.vfs.getMountAt(rp.mount, parent); mnt != nil {
-			rp.nextMount = mnt
-			return nil, resolveMountPointError{}
-		}
-	}
-	return parent, nil
+	return false, nil
 }
 
-// ResolveChild returns the VFS child of d with the given name. It does not
-// take a reference on the returned Dentry. If no such child exists,
-// ResolveChild returns (nil, nil).
-//
-// Preconditions: There are no concurrent mutators of d.
-func (rp *ResolvingPath) ResolveChild(d *Dentry, name string) (*Dentry, error) {
-	child := d.children[name]
-	if child == nil {
-		return nil, nil
+// CheckMount is called after resolving the parent or child of another Dentry
+// to d. If d is a mount point, such that path resolution should switch to
+// another Mount, CheckMount returns a non-nil error. Otherwise, CheckMount
+// returns nil.
+func (rp *ResolvingPath) CheckMount(d *Dentry) error {
+	if !d.isMounted() {
+		return nil
 	}
-	if child.isMounted() {
-		if mnt := rp.vfs.getMountAt(rp.mount, child); mnt != nil {
-			rp.nextMount = mnt
-			return nil, resolveMountPointError{}
-		}
-	}
-	return child, nil
-}
-
-// ResolveComponent returns the Dentry reached by starting at d and resolving
-// the current path component in the stream represented by rp. It does not
-// advance the stream. It does not take a reference on the returned Dentry. If
-// no such Dentry exists, ResolveComponent returns (nil, nil).
-//
-// Preconditions: !rp.Done(). There are no concurrent mutators of d.
-func (rp *ResolvingPath) ResolveComponent(d *Dentry) (*Dentry, error) {
-	switch pc := rp.Component(); pc {
-	case ".":
-		return d, nil
-	case "..":
-		return rp.ResolveParent(d)
-	default:
-		return rp.ResolveChild(d, pc)
+	if mnt := rp.vfs.getMountAt(rp.mount, d); mnt != nil {
+		rp.nextMount = mnt
+		return resolveMountPointError{}
 	}
+	return nil
 }
 
 // ShouldFollowSymlink returns true if, supposing that the current path
diff --git a/pkg/sentry/vfs/vfs_state_autogen.go b/pkg/sentry/vfs/vfs_state_autogen.go
index 1f505c4bf..7fc34dedd 100755
--- a/pkg/sentry/vfs/vfs_state_autogen.go
+++ b/pkg/sentry/vfs/vfs_state_autogen.go
@@ -12,21 +12,15 @@ import (
 func (x *Dentry) beforeSave() {}
 func (x *Dentry) save(m state.Map) {
 	x.beforeSave()
-	m.Save("parent", &x.parent)
-	m.Save("name", &x.name)
-	m.Save("flags", &x.flags)
+	m.Save("dead", &x.dead)
 	m.Save("mounts", &x.mounts)
-	m.Save("children", &x.children)
 	m.Save("impl", &x.impl)
 }
 
 func (x *Dentry) afterLoad() {}
 func (x *Dentry) load(m state.Map) {
-	m.Load("parent", &x.parent)
-	m.Load("name", &x.name)
-	m.Load("flags", &x.flags)
+	m.Load("dead", &x.dead)
 	m.Load("mounts", &x.mounts)
-	m.Load("children", &x.children)
 	m.Load("impl", &x.impl)
 }