linux-kernel - question about splice

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Message-ID: <201307261507562231224@gmail.com>
Date:	Fri, 26 Jul 2013 15:08:00 +0800
From:	majianpeng <majianpeng@...il.com>
To:	viro <viro@...iv.linux.org.uk>
Cc:	linux-fsdevel <linux-fsdevel@...r.kernel.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: question about splice

Hi all,
	I used splice and found a prolem(at least i call).
The demo is:
A:splice(regularfileA--->pipe);
B:splice(pipe--->regularfileB)
Before do B, we modify the data of regA which now in pipe. The data to regularfileB willbe change.
If we used the buff
A:read(regA, buff);
B: write(buff, regB);
After A, the contend of regA can't effect the buff.
Review the code of splice,I know the pipe share the pagecache of regA.
Maybe this is not a problem or am i missing something?

Thanks!
Jianpeng Ma