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 AAD57C636CC for ; Mon, 13 Feb 2023 09:45:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231266AbjBMJpK (ORCPT ); Mon, 13 Feb 2023 04:45:10 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:53820 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230509AbjBMJol (ORCPT ); Mon, 13 Feb 2023 04:44:41 -0500 Received: from formenos.hmeau.com (167-179-156-38.a7b39c.syd.nbn.aussiebb.net [167.179.156.38]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E93EA3C21; Mon, 13 Feb 2023 01:44:25 -0800 (PST) Received: from loth.rohan.me.apana.org.au ([192.168.167.2]) by formenos.hmeau.com with smtp (Exim 4.94.2 #2 (Debian)) id 1pRV5S-00AXIL-A4; Mon, 13 Feb 2023 17:25:27 +0800 Received: by loth.rohan.me.apana.org.au (sSMTP sendmail emulation); Mon, 13 Feb 2023 17:25:26 +0800 Date: Mon, 13 Feb 2023 17:25:26 +0800 From: Herbert Xu To: Dave Chinner Cc: torvalds@linux-foundation.org, metze@samba.org, axboe@kernel.dk, linux-fsdevel@vger.kernel.org, linux-api@vger.kernel.org, io-uring@vger.kernel.org, linux-kernel@vger.kernel.org, viro@zeniv.linux.org.uk, samba-technical@lists.samba.org Subject: Re: copy on write for splice() from file to pipe? Message-ID: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230210061953.GC2825702@dread.disaster.area> X-Newsgroups: apana.lists.os.linux.kernel Precedence: bulk List-ID: X-Mailing-List: io-uring@vger.kernel.org Dave Chinner wrote: > > IOWs, the application does not care if the data changes whilst they > are in transport attached to the pipe - it only cares that the > contents are stable once they have been delivered and are now wholly > owned by the network stack IO path so that the OTW encodings > (checksum, encryption, whatever) done within the network IO path > don't get compromised. Is this even a real problem? The network stack doesn't care at all if you modify the pages while it's being processed. All the things you've mentioned (checksum, encryption, etc.) will be self-consistent on the wire. Even when actual hardware offload is involved it's hard to see how things could possibly go wrong unless the hardware was going out of its way to do the wrong thing by fetching from memory twice. Cheers, -- Email: Herbert Xu Home Page: http://gondor.apana.org.au/~herbert/ PGP Key: http://gondor.apana.org.au/~herbert/pubkey.txt