From mboxrd@z Thu Jan 1 00:00:00 1970 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.subspace.kernel.org (Postfix) with ESMTPS id 5B83549620 for ; Fri, 23 May 2025 12:53:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=198.137.202.133 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748004786; cv=none; b=WacYAMqKPX4gp/lrf2HhjXSP7+aFGz8tDT5onzvyfE8/fnTAV3imRaxf1/h/x4jwhceU/T85s62FfC0t6j7sxcQAc6Bj1mkGKf/yNbbb/GwT+Y+7nJ018r1suvC2E0acnmGM1vTW3JW3mSE0uZLmqhi2hzH+IP2t6Lv2MN8V2pU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1748004786; c=relaxed/simple; bh=ZGKTgC7L/XjurUQ1b2cDuvyj2tiXNKWr4yJpbr2P+eM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=W4vo4BuOXZUn4km9pU9AHogfSusf792Be+NniTSpybyATf1Wbpmv+kyLy2maqyA4Au497CN7R3Y4sgthHpncjK4evY0Gs87MKinx/uHnKnHRKpjfXCfTeqyxzGZitJrkc39AFekdt12tyi6BpXUVKSmwV4UZxuYt9NMw6Oq9fdU= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b=CWH+0cXa; arc=none smtp.client-ip=198.137.202.133 Authentication-Results: smtp.subspace.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: smtp.subspace.kernel.org; spf=none smtp.mailfrom=bombadil.srs.infradead.org Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="CWH+0cXa" DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=bombadil.20210309; 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=Gv+Cu1VNu8jkjXHy0G/6SVAtV7Y+ResFYJBAHJAmNpY=; b=CWH+0cXarJAE8EDe2kvQZokE1P lUR7LjSxTeauPS7owop6RnGpaxRT0GRJa77DY8i3dCvolLVAu5BTxpDNO8gtiz8L5g6urDYbrbGdF pNo4T0FXD9QTvqtHvLze/mAltAl+F3eKSG3SUXunvdm/SqSg0okmHa4Z7kA4lDgdMGGfYWlxM/qVz 1tHwVoTkBCSsULqflBQNAFOrnDSXcHfXMWsh0eHMxDkza1+7LhE05s91EbX9EjmvlJY+io9xj646K FShoH8E7aAkRnwCPbq4EXiPdFc5U/LzR9ksBmckCTGwJmWY3fubz9cLRSeUY1GUv3h9jBN3s26Doz FCOEM6yA==; 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> Precedence: bulk X-Mailing-List: linux-block@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: 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-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html 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.