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 2B2BBC5ACC1 for ; Fri, 20 Feb 2026 16:45:38 +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=mX3Gfh9y0Kt7rFh9kNJbU6lmghBDbpYgwSqpoEcYuv0=; b=lwfxzFHQKQXbSwgi8aZ1hE9+gF heTwOUejOui+2hyckpX/K/AamoCFGQ2jf9RQgnQKR4fbIg+Sv4CbjnGTXwnImgD5+Zm2IxfCb4HSm 9nNKuOdnwPgkO1gfvgd7oz35Fp3gugQ5iDPA44Vs5cX1I5nmA+EiyT/Jju0nQ/aJfkuXXH6f0Q7ok SjXhPKf752NhlmmnyqnkaKTne6ux3lSSptFm9UqixV4HZTseZzUDE6PTJvpK/SSpnVoyAH5ROuK6H U89sj+d9oMioGbwIxb8FrphjIcFawjtnQSqGOby2iX5wwNkX7Ixy5555wiiSHuABttaXQNhiV3p/9 Decd3e4g==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vtTdI-0000000FJQE-2nNF; Fri, 20 Feb 2026 16:45:36 +0000 Received: from verein.lst.de ([213.95.11.211]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vtTdG-0000000FJPR-2Amd for linux-nvme@lists.infradead.org; Fri, 20 Feb 2026 16:45:35 +0000 Received: by verein.lst.de (Postfix, from userid 2407) id CDB3C68BFE; Fri, 20 Feb 2026 17:45:30 +0100 (CET) Date: Fri, 20 Feb 2026 17:45:30 +0100 From: Christoph Hellwig To: Hannes Reinecke Cc: Christoph Hellwig , Hannes Reinecke , Keith Busch , Sagi Grimberg , linux-nvme@lists.infradead.org, Abdulla Nasirli Subject: Re: [PATCHv2] nvmet: lift blocksize restriction to 64k Message-ID: <20260220164530.GB15907@lst.de> References: <20260220151259.20372-1-hare@kernel.org> <20260220153237.GB14359@lst.de> <8d50557c-86a8-4364-b5e7-d40b36ad9f60@suse.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <8d50557c-86a8-4364-b5e7-d40b36ad9f60@suse.de> 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-20260220_084534_718935_F20C24A7 X-CRM114-Status: GOOD ( 14.35 ) 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 Fri, Feb 20, 2026 at 05:42:25PM +0100, Hannes Reinecke wrote: > On 2/20/26 16:32, Christoph Hellwig wrote: >> On Fri, Feb 20, 2026 at 04:12:59PM +0100, Hannes Reinecke wrote: >>> With commit 47dd67532303 ("block/bdev: lift block size restrictions to 64k") >>> we can now support up to 64k block sizes, so lift the restriction on 4k for >>> file-backed namespaces. >> >> Still not sure this is a great idea by default. Yes, modern Linux supports >> 64k sector sizes, but even then just for a few file systems. And this >> changes existing setups, which will now break when upgrading the kernel. >> > How so? There cannot be any existing nvmet setup with an LBS backing > device, as the device will be rejected when trying to setup the target. > Which breakage do you see here? There can be a setup with a large i_blkbits that we limit to 4k export LBA size right now, and with your patch it will be exposed as something larger.