Re: [PATCH] splice: direct call for default_file_splice*()

[Christoph Hellwig <hch@infradead.org>]

On Mon, Jan 20, 2020 at 11:49:46PM +0300, Pavel Begunkov wrote:
> Indirect calls could be very expensive nowadays, so try to use direct calls
> whenever possible.

... and independent of that your new version is much shorter and easier
to read.  But it could be improved a tiny little bit further:

>  	if (out->f_op->splice_write)
> -		splice_write = out->f_op->splice_write;
> +		return out->f_op->splice_write(pipe, out, ppos, len, flags);
>  	else
> -		splice_write = default_file_splice_write;
> -
> -	return splice_write(pipe, out, ppos, len, flags);
> +		return default_file_splice_write(pipe, out, ppos, len, flags);

No need for the else after an return.

>  	if (in->f_op->splice_read)
> -		splice_read = in->f_op->splice_read;
> +		return in->f_op->splice_read(in, ppos, pipe, len, flags);
>  	else
> -		splice_read = default_file_splice_read;
> -
> -	return splice_read(in, ppos, pipe, len, flags);
> +		return default_file_splice_read(in, ppos, pipe, len, flags);

Same here.