Re: [PATCH v2 4/4] splice: fix updating sd->pos wrongly

Changli Gao
2010-05-28T10:55:45Z

On Fri, May 28, 2010 at 6:13 PM, Miklos Szeredi <miklos@szeredi.hu> wrote:
> On Fri, 28 May 2010, Changli Gao wrote:
>> On Fri, May 28, 2010 at 5:42 PM, Miklos Szeredi <miklos@szeredi.hu> wrote:
>> > On Wed, 26 May 2010, Changli Gao wrote:
>> >> fix updating sd->pos wrongly.
>> >>
>> >> In error path, we don't need to updating sd->pos, if the file isn't seekable.
>> >
>> > This patch is nonsense.  Why should we handle sd->pos != 0 case
>> > differently?
>> >
>>
>> If the in file isn't seekable, its splice_read won't update *ppos, so
>> in the error path, we'd better not change it too. Otherwise, some
>> assumption will go wrong.
>
> That may be true, but the patch is still nonsense.
>
> Look, your patch is updating/not updating sd->pos based on whether it
> is zero or not.  It will prevent updating the position for sockets,
> but it will also prevent updating the position for regular files if
> the position is zero, which is really not what we want.

I think you misread my patch. Before checking the sd->pos, sd->pos
already is updated with the value returned by splice_read(), so if in
file is seekabble, sd->pos is non-zero when I checking it.

--
Regards，
Changli Gao(xiaosuo@gmail.com)