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

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Message-ID: <333a7628-904b-c02a-b871-298b4833974a@gmail.com>
Date:   Mon, 4 Jan 2021 16:54:42 +0000
From:   Pavel Begunkov <asml.silence@...il.com>
To:     Christoph Hellwig <hch@...radead.org>
Cc:     linux-block@...r.kernel.org, Jens Axboe <axboe@...nel.dk>,
        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 04/01/2021 16:17, Christoph Hellwig wrote:
> 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?

Definitely won't hurt. Thanks for taking a look

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

-- 
Pavel Begunkov