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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 5F4BDC7EE37 for ; Thu, 8 Jun 2023 13:50:38 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236729AbjFHNuf (ORCPT ); Thu, 8 Jun 2023 09:50:35 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:34916 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S236252AbjFHNu0 (ORCPT ); Thu, 8 Jun 2023 09:50:26 -0400 Received: from bombadil.infradead.org (bombadil.infradead.org [IPv6:2607:7c80:54:3::133]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id F420F26AD; Thu, 8 Jun 2023 06:50:24 -0700 (PDT) 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=26X3eXQKS7NeIHOPgSnnyuKz8M8nhouJgb1HCFlt9gU=; b=oxnl+ytCH/AYLiO8lGsaGTSgAL YKAhmz3KWLG52xTtZ3vVlzOoXhqLAE+TSDLYtiUMLgMfWgpBomxV6NcPL6FCI9kZwk5bogGjZOPLI 8QnbaKMgK9r0pLr5cxZR/iblydbJMDtaB1NxFguDycK5q8EbVJhgUczSAh/3xz4/50h2hd6QRO2Vb AJKily0ob+IT+C7Jr0UjGjkAuljbZavKlpTolZdO19kaSy3qPAuDfQRNQkFvlbYQt17NVlmUv2c/e feloqZah/8iJ6KrYviLmgJmxmK61OEwauO0fphZdNmbYWghbE9QuD17HBUBrSKATOW5r70soVneqm A6ckZIHA==; Received: from hch by bombadil.infradead.org with local (Exim 4.96 #2 (Red Hat Linux)) id 1q7G1n-009W7J-1c; Thu, 08 Jun 2023 13:50:15 +0000 Date: Thu, 8 Jun 2023 06:50:15 -0700 From: Christoph Hellwig To: Matthew Wilcox Cc: Luis Chamberlain , hch@infradead.org, djwong@kernel.org, dchinner@redhat.com, kbusch@kernel.org, hare@suse.de, ritesh.list@gmail.com, rgoldwyn@suse.com, jack@suse.cz, patches@lists.linux.dev, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-block@vger.kernel.org, p.raghav@samsung.com, da.gomez@samsung.com, rohan.puri@samsung.com, rpuri.linux@gmail.com, corbet@lwn.net, jake@lwn.net Subject: Re: [RFC 4/4] bdev: extend bdev inode with it's own super_block Message-ID: References: <20230608032404.1887046-1-mcgrof@kernel.org> <20230608032404.1887046-5-mcgrof@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org. See http://www.infradead.org/rpr.html Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Thu, Jun 08, 2023 at 02:37:34PM +0100, Matthew Wilcox wrote: > On Wed, Jun 07, 2023 at 08:24:04PM -0700, Luis Chamberlain wrote: > > We currently share a single super_block for the block device cache, > > each block device corresponds to one inode on that super_block. This > > implicates sharing one aops operation though, and in the near future > > we want to be able to instead support using iomap on the super_block > > for different block devices. > > > -struct super_block *blockdev_superblock __read_mostly; > > Did we consider adding > > +struct super_block *blockdev_sb_iomap __read_mostly; > > and then considering only two superblocks instead of having a list of > all bdevs? Or why the heck we would even do this to start with? iomap has absolutely nothing to do with superblocks. Now maybe it might make sense to have a superblock per gendisk just to remove all the weird special casing for the bdev inode in the writeback code. But that's something entirely different than this patch.