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 10C39C44501 for ; Thu, 16 Jul 2026 12:21:24 +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=vN6BZjNAL13b8uR7AaLLQSpyg/U4Cqi6Fq/CQ0mKf2g=; b=hdBJ1S5z00XbYGEmoAyH4ZQ9Gx OmWiSm1HiGaKNyfJco1kZvYSiA2nZPR68HDDDUg8FA42L65yPlyTf3Teh+LF/PR93dxxewbvGmSOp ecXSTn/ADESAy32PHAlBkuLoN5A2kLdZKUsex0/c9nmPSr8QVot4s0zfOyZc9mS3nn3Q8kKR3bMeO OIf9mvXM5MWdUUz8WXPZ7Sb7XxjrhuMUbUaUnBthxKOiHpIG3iDrf0/kD/Z0uqaeCBvkQh4GRbTkW FiZDzlZehjbqhjqaWZzfQO31e9OMqW2mfgOL6B25d1qxFkXLKF8tVquTmlvZAtYODDLShRHSWMpjL JAEFDoHQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.99.1 #2 (Red Hat Linux)) id 1wkL5c-0000000HEnd-2CK5; Thu, 16 Jul 2026 12:21:20 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.99.1 #2 (Red Hat Linux)) id 1wkL5Z-0000000HElB-1rB7 for linux-nvme@lists.infradead.org; Thu, 16 Jul 2026 12:21:19 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id 9D99C68AFE; Thu, 16 Jul 2026 14:21:08 +0200 (CEST) Date: Thu, 16 Jul 2026 14:21:08 +0200 From: Christoph Hellwig To: Keith Busch Cc: Caleb Sander Mateos , Christoph Hellwig , Jens Axboe , Sagi Grimberg , "Martin K. Petersen" , linux-block@vger.kernel.org, linux-nvme@lists.infradead.org, linux-kernel@vger.kernel.org Subject: Re: [RFC PATCH 2/2] nvme/core: advertise BLK_EXPECTED_REF_TAG_CAPABLE Message-ID: <20260716122108.GA30437@lst.de> References: <20260627061933.2187447-1-csander@purestorage.com> <20260627061933.2187447-3-csander@purestorage.com> <20260714135310.GB714@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 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260716_052117_645045_4CD09C48 X-CRM114-Status: GOOD ( 17.20 ) 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 Wed, Jul 15, 2026 at 10:01:39AM -0600, Keith Busch wrote: > > I mentioned this in the cover letter (and that's why I marked these > > patches "RFC"). Unless you have a clever idea, it does seem like an > > insurmountable obstacle here. > > We had a similar problem when we enabled PI at the end of the metadata > rather than just at the beginning. This left machines unbootable after > upgrading the kernel, so we have a module parameter to turn off support > for the feature. It's an unpleasant solution as there's no upgrade path > to ever turn on the feature without a format first. We could opt into not faking up type 1 PI with a REQ_ or BIP_ flag. But we'd really need a user that actually wants it first.