linux-kernel - Re: [PATCH] splice: direct call for default_file

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Message-ID: <20200130165425.GA8872@infradead.org>
Date:   Thu, 30 Jan 2020 08:54:25 -0800
From:   Christoph Hellwig <hch@...radead.org>
To:     Pavel Begunkov <asml.silence@...il.com>
Cc:     Alexander Viro <viro@...iv.linux.org.uk>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] splice: direct call for default_file_splice*()

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.