linux-kernel - Re: [PATCH] splice: fix wrong __splice_from

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Message-ID: <87hco4v847.fsf@duaron.myhome.or.jp>
Date:	Mon, 16 Jul 2007 21:35:52 +0900
From:	OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
To:	Jens Axboe <jens.axboe@...cle.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH] splice: fix wrong __splice_from_pipe() usage

Jens Axboe <jens.axboe@...cle.com> writes:

>> nfsd_vfs_read() path.
>> 
>> nfsd_vfs_read()
>>     splice_direct_to_actor()
>>         while(len) {
>>             do_splice_to()                     [update sd->pos]
>>                 -> generic_file_splice_read()  [read from sd->pos]
>>             nfsd_direct_splice_actor()
>>                 -> __splice_from_pipe()        [update sd->pos]
>>         }
>> 
>> do_splice_to() updates sd->pos for read, and pass updated sd to
>> __splice_from_pipe(), and __splice_from_pipe() updates sd->pos for
>> write. So, next do_splice_to() read from wrong position.
>
> Ah, I see. Copying the structure over would work, but it seems like a
> big work-around for something that is essentially bad behaviour in the
> splice core for direct splicing.
>
> Can you check if this works for you?

Simple test was done. The patch works for me.

Thanks.
-- 
OGAWA Hirofumi <hirofumi@...l.parknet.co.jp>
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