Have fuse.DeviceFD hold reference on fuse.filesystem.

This is actually just b/168751672 again; cl/332394146 was incorrectly reverted
by cl/341411151. Document the reference holder to reduce the likelihood that
this happens again.

Also document a few other bugs observed in the process.

PiperOrigin-RevId: 342339144

1 files changed, 3 insertions, 10 deletions

diff --git a/pkg/sentry/fsimpl/fuse/utils_test.go b/pkg/sentry/fsimpl/fuse/utils_test.go
index b2f4276b8..2c0cc0f4e 100644
--- a/pkg/sentry/fsimpl/fuse/utils_test.go
+++ b/pkg/sentry/fsimpl/fuse/utils_test.go
@@ -52,28 +52,21 @@ func setup(t *testing.T) *testutil.System {
 // newTestConnection creates a fuse connection that the sentry can communicate with
 // and the FD for the server to communicate with.
 func newTestConnection(system *testutil.System, k *kernel.Kernel, maxActiveRequests uint64) (*connection, *vfs.FileDescription, error) {
-	vfsObj := &vfs.VirtualFilesystem{}
 	fuseDev := &DeviceFD{}
 
-	if err := vfsObj.Init(system.Ctx); err != nil {
-		return nil, nil, err
-	}
-
-	vd := vfsObj.NewAnonVirtualDentry("genCountFD")
+	vd := system.VFS.NewAnonVirtualDentry("fuse")
 	defer vd.DecRef(system.Ctx)
-	if err := fuseDev.vfsfd.Init(fuseDev, linux.O_RDWR|linux.O_CREAT, vd.Mount(), vd.Dentry(), &vfs.FileDescriptionOptions{}); err != nil {
+	if err := fuseDev.vfsfd.Init(fuseDev, linux.O_RDWR, vd.Mount(), vd.Dentry(), &vfs.FileDescriptionOptions{}); err != nil {
 		return nil, nil, err
 	}
 
 	fsopts := filesystemOptions{
 		maxActiveRequests: maxActiveRequests,
 	}
-	fs, err := newFUSEFilesystem(system.Ctx, 0, &fsopts, &fuseDev.vfsfd)
+	fs, err := newFUSEFilesystem(system.Ctx, system.VFS, &FilesystemType{}, fuseDev, 0, &fsopts)
 	if err != nil {
 		return nil, nil, err
 	}
-	fs.VFSFilesystem().Init(vfsObj, nil, fs)
-
 	return fs.conn, &fuseDev.vfsfd, nil
 }