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 41677C02194 for ; Tue, 4 Feb 2025 13:49:17 +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=76c1TtSnx6JZufkNQiY8vEierEYkzU4cNo1gbjwWYaQ=; b=HIGEZigxnc52OC546/+uy6cGW+ cv/WtNcJ+ZOXVdTLWKC19cdTMl+FWgFUw+K2P+CJF86LBor0AakJmTZ3cn94GG7Sk7R2TW9S0s0VA zJUreETwCo4yKydOf8YvXdIORxW3d03apIcS0eIty3MeHJzib2n46BQBiwZepDYoslrxtyg9R+rHz jqcWxww6HMOYcgoHFFHDhXoM4bkJBs3qzbtVrjSvErYlgaG23PJo5ntByhrgMK62Ule7DQGVPFU5U CGnCiwz9X2EL/M0vLamLW9pcfMaNrcMpLjx4qV3+qc8sHpb406mnZbFVroC96nFZOeH7I9OwNc3Nv 8Z/aN0wA==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98 #2 (Red Hat Linux)) id 1tfJIg-00000000Zvs-1frQ; Tue, 04 Feb 2025 13:49:14 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.98 #2 (Red Hat Linux)) id 1tfJIc-00000000Zur-1tSh for linux-nvme@lists.infradead.org; Tue, 04 Feb 2025 13:49:12 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 2825968D05; Tue, 4 Feb 2025 14:49:02 +0100 (CET) Date: Tue, 4 Feb 2025 14:49:01 +0100 From: Christoph Hellwig To: "Martin K. Petersen" Cc: Christoph Hellwig , Kanchan Joshi , josef@toxicpanda.com, dsterba@suse.com, clm@fb.com, axboe@kernel.dk, kbusch@kernel.org, linux-btrfs@vger.kernel.org, linux-nvme@lists.infradead.org, linux-block@vger.kernel.org, gost.dev@samsung.com Subject: Re: [RFC 0/3] Btrfs checksum offload Message-ID: <20250204134901.GA11902@lst.de> References: <20250129140207.22718-1-joshi.k@samsung.com> <20250131074424.GA16182@lst.de> <20250204051208.GG28103@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.17 (2007-11-01) X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20250204_054910_630005_67E6C28B X-CRM114-Status: GOOD ( 15.14 ) 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 Tue, Feb 04, 2025 at 07:52:38AM -0500, Martin K. Petersen wrote: > I have been told that some arrays use it to disable PI when writing the > RAID parity blocks. I guess that makes sense if the array firmware is > mixing data and parity blocks in a single write operation. For my test > tool I just use WRPROTECT=3 to disable checking when writing "bad" PI. Hmm, why would you disable PI for parity blocks? But yes, outside of Linux there might be uses. Just thinking of a "perfect" format for our needs. > > > > That would also work fine. NVMe supports 4byte crc32c + 2 byte app tag + > > 12 byte guard tag / storage tag and 8-byte crc64 + 2 byte app tag + 6 > > byte guard / storage tag, although Linux only supports the latter so far. > > Yep, the CRC32C variant should be easy to wire up. I've thought about > the storage tag but haven't really come up with a good use case. It's > essentially the same situation as with the app tag. Exactly, it's an app tag by other means.