linux-kernel - Re: [PATCH v2 1/7] splice: don't generate zero-len segement bvecs

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Message-ID: <20210104161716.GA68600@infradead.org>
Date:   Mon, 4 Jan 2021 16:17:16 +0000
From:   Christoph Hellwig <hch@...radead.org>
To:     Pavel Begunkov <asml.silence@...il.com>
Cc:     linux-block@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
        Christoph Hellwig <hch@...radead.org>,
        Matthew Wilcox <willy@...radead.org>,
        Ming Lei <ming.lei@...hat.com>,
        Johannes Weiner <hannes@...xchg.org>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        "Martin K . Petersen" <martin.petersen@...cle.com>,
        Jonathan Corbet <corbet@....net>, linux-xfs@...r.kernel.org,
        linux-fsdevel@...r.kernel.org, io-uring@...r.kernel.org,
        linux-kernel@...r.kernel.org, target-devel@...r.kernel.org,
        linux-scsi@...r.kernel.org, linux-doc@...r.kernel.org
Subject: Re: [PATCH v2 1/7] splice: don't generate zero-len segement bvecs

On Sat, Jan 02, 2021 at 03:17:33PM +0000, Pavel Begunkov wrote:
> iter_file_splice_write() may spawn bvec segments with zero-length. In
> preparation for prohibiting them, filter out by hand at splice level.
> 
> Signed-off-by: Pavel Begunkov <asml.silence@...il.com>
> ---
>  fs/splice.c | 9 +++++----
>  1 file changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/splice.c b/fs/splice.c
> index 866d5c2367b2..7299330c3270 100644
> --- a/fs/splice.c
> +++ b/fs/splice.c
> @@ -644,7 +644,6 @@ iter_file_splice_write(struct pipe_inode_info *pipe, struct file *out,
>  		ret = splice_from_pipe_next(pipe, &sd);
>  		if (ret <= 0)
>  			break;
> -

Spurious empty line removal..

> +			if (!this_len)
> +				continue;

Maybe throw in a comment on why we skip empty segments here?

Otherwise looks good:

Reviewed-by: Christoph Hellwig <hch@....de>