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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 41AA4C54ED0 for ; Fri, 23 May 2025 13:14:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:In-Reply-To:Content-Type: MIME-Version:References:Message-ID:Subject:Cc:To:From:Date:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=Gv+Cu1VNu8jkjXHy0G/6SVAtV7Y+ResFYJBAHJAmNpY=; b=iYqJBdKVMPXX5qUZ7irszAWVdJ RV6MeZstVsPs59oa7oiNM6XDbBhCzCEEtAFHGYEsZ2eZzqaQGxp4nVocs+/9sQ4ei8GMF/GXuoEfN ZiWuthoGeM8QNcbJBukE3uSUmtKXRXlde+4EvOAsdVdBpjhclqnlCQZRgKrugzxjPGQJUWfgy0E1j L865svU5RRVz1/z9+cGfO9qoqJ3tC/7IrmFsvHr0+YiHG1fK6ssVKtRtGtT42ec9xZooKCbZO0oQt Ond26IUzsN8Q26X+rkiX/4kfHWE1mVeagwMhGbmRTrp++aG6bDxOzbbBS3xhDb1ujRihJTCt1rQBZ bHxnmruA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1uISE0-00000003uwf-3sv8; Fri, 23 May 2025 13:14:12 +0000 Received: from hch by bombadil.infradead.org with local (Exim 4.98.2 #2 (Red Hat Linux)) id 1uIRtY-00000003rVJ-3GKW; Fri, 23 May 2025 12:53:04 +0000 Date: Fri, 23 May 2025 05:53:04 -0700 From: Christoph Hellwig To: Bart Van Assche Cc: Keith Busch , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, Keith Busch Subject: Re: [PATCH 0/5] block: another block copy offload Message-ID: References: <20250521223107.709131-1-kbusch@meta.com> <2243538c-ca19-4576-af94-ed6e1790c82d@acm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <2243538c-ca19-4576-af94-ed6e1790c82d@acm.org> X-BeenThere: linux-nvme@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "Linux-nvme" Errors-To: linux-nvme-bounces+linux-nvme=archiver.kernel.org@lists.infradead.org On Thu, May 22, 2025 at 08:52:19AM -0700, Bart Van Assche wrote: > Before any copy offloading code is merged in the upstream kernel, a plan > should be presented for how this partial implementation will evolve into > a generic solution. As Hannes already pointed out, support for > copying between block devices is missing. SCSI support is missing. > Device mapper support is missing. What is the plan for evolving this > patch series into a generic solution? Is it even possible to evolve this > patch series into a generic solution? While I agree with some of this, please keep cross-device copies out of the picture here. The cross-namepace copies and cross LUN copies in SCSI are a horrible misfeature that is almost impossible to implement in an I/O stack. If someone ever manages to get them to work they most certainly would have to use a very different infrastructure outside the block layer.