sandbox/mount: pass custom tmpfs name

The tmpfs driver allows arbitrary fsname.

Signed-off-by: Ophestra <cat@gensokyo.uk>

internal/sandbox/mount.go

@@ -82,7 +82,7 @@ func bindMount(src, dest string, flags int) error {
 		fmt.Sprintf("cannot bind %q on %q:", src, dest))
 }
 
-func mountTmpfs(name string, size int, perm os.FileMode) error {
+func mountTmpfs(fsname, name string, size int, perm os.FileMode) error {
 	target := toSysroot(name)
 	if err := os.MkdirAll(target, perm); err != nil {
 		return err
@@ -91,7 +91,7 @@ func mountTmpfs(name string, size int, perm os.FileMode) error {
 	if size > 0 {
 		opt += fmt.Sprintf(",size=%d", size)
 	}
-	return fmsg.WrapErrorSuffix(syscall.Mount("tmpfs", target, "tmpfs",
+	return fmsg.WrapErrorSuffix(syscall.Mount(fsname, target, "tmpfs",
 		syscall.MS_NOSUID|syscall.MS_NODEV, opt),
 		fmt.Sprintf("cannot mount tmpfs on %q:", name))
 }

internal/sandbox/sequential.go

@@ -87,7 +87,7 @@ func (t *MountTmpfs) apply(*InitParams) error {
 		return fmsg.WrapError(syscall.EBADE,
 			fmt.Sprintf("size %d out of bounds", t.Size))
 	}
-	return mountTmpfs(t.Path, t.Size, t.Perm)
+	return mountTmpfs("tmpfs", t.Path, t.Size, t.Perm)
 }
 
 func (t *MountTmpfs) Is(op Op) bool  { vt, ok := op.(*MountTmpfs); return ok && *t == *vt }