return len(p), nil
	case <-w.ctx.Done():
		return 0, context.Cause(w.ctx)
	}
}

// WriterToChannel will return an io.Writer that writes to the given channel.
// The context both allows returning errors on writes and to ensure that
// this isn't abandoned if the channel is no longer being read from.
func WriterToChannel(ctx context.Context, ch chan<- []byte) io.Writer {
	return &writerWrapper{ch: ch, ctx: ctx}
}

	if !s.checkID(opts.DiskID) {
		return grid.NewRemoteErr(errDiskNotFound)
	}

	ctx, cancel := context.WithCancel(ctx)
	defer cancel()
	return grid.NewRemoteErr(s.getStorage().WalkDir(ctx, opts, grid.WriterToChannel(ctx, out)))