From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D947AC05027 for ; Thu, 9 Feb 2023 14:11:50 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229595AbjBIOLu (ORCPT ); Thu, 9 Feb 2023 09:11:50 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40312 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230344AbjBIOLt (ORCPT ); Thu, 9 Feb 2023 09:11:49 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id DFAFC5D3D0; Thu, 9 Feb 2023 06:11:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=OLfeb/1peUB0Uk6OCxp5bH/mik1H6dPr8FEIIkuL/QU=; b=JbYEsNAVDN51UJgX9qx6k2eWsB 07OxOMxmQRAsKV4YCUUrdkihKeBBP+2v3yOzF5lMH2RU3uRzAPvxbFhjWsOGAZ5ej64w7YIiUOC/q CyqW+bPeytq1LKDKZNG8kHZ40wiRBsT+vZm0yzikNRVt+PamelOijN2LOAX/972YiI2nU3VMfcBwy DrNSYpn6HJBxJjd5YrKF++aI3VpeX5P/oiaE/kGnSypHx47JkJ7Bq57GujAobCyZgg+NWgy6XlEso 32JWzqTYOr8NbgJAitEXC8RG1uA55A7/Tr6RfZ0VXSM4B8rbIOvpQBD9K6YWMJ/c21YD+BkFx2Kif EpsWohxw==; Received: from willy by casper.infradead.org with local (Exim 4.94.2 #2 (Red Hat Linux)) id 1pQ7eC-002Fh2-Uk; Thu, 09 Feb 2023 14:11:36 +0000 Date: Thu, 9 Feb 2023 14:11:36 +0000 From: Matthew Wilcox To: Stefan Metzmacher Cc: Linus Torvalds , linux-fsdevel , Linux API Mailing List , io-uring , "linux-kernel@vger.kernel.org" , Al Viro , Samba Technical Subject: Re: copy on write for splice() from file to pipe? Message-ID: References: <0cfd9f02-dea7-90e2-e932-c8129b6013c7@samba.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <0cfd9f02-dea7-90e2-e932-c8129b6013c7@samba.org> Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org On Thu, Feb 09, 2023 at 02:55:59PM +0100, Stefan Metzmacher wrote: > Hi Linus and others, > > as written in a private mail before, I'm currently trying to > make use of IORING_OP_SPLICE in order to get zero copy support > in Samba. I have to ask why. In a modern network, isn't all data encrypted? So you have to encrypt into a different buffer, and then you checksum that buffer. So it doesn't matter if writes can change the page cache after you called splice(), you just need to have the data be consistent so the checksum doesn't change.