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 X-Spam-Level: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id CD1BBC56201 for ; Fri, 20 Nov 2020 16:00:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 4836422264 for ; Fri, 20 Nov 2020 16:00:16 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="dKbyJHe0" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728919AbgKTQAP (ORCPT ); Fri, 20 Nov 2020 11:00:15 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:46348 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728200AbgKTQAO (ORCPT ); Fri, 20 Nov 2020 11:00:14 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 88B73C0613CF; Fri, 20 Nov 2020 08:00:14 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; 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=K5DwT3XZlV3t3RqqSgbM35Y3HrzhNkm8y+Dk2IlqgSg=; b=dKbyJHe0CTU5aQ7qzS3y+R7HzS IKnP9HvhkePlkizqwksisFX9ItaAwMtV42JJBmP3ZX68rybYyhhyxN6HF+4s2kqLrzwOxCN590LXF ym0WaBVLMdq9rLFtADBHBTFGjcyPZEqJfC7pbYTLnera5pnBeS3gKB7QoEHsSi8lIOiJp2cbk5Dht 3B0uQlIfZ8f/1YczBdK4QRRNeBKzTo4B1VHMay+VPY7OTUi8keSXIo2ShWdFB8ho8zwbUkIe8+1eP wuIgrB00p1rgPw8SIw6y1czXZtN+QrCR9MWZkdKvvhRmCPfud3TmejnBZGx0dJq2Oq4i98pjwEUY2 dBwSlL3g==; Received: from willy by casper.infradead.org with local (Exim 4.92.3 #3 (Red Hat Linux)) id 1kg8pI-0005Bl-Jz; Fri, 20 Nov 2020 15:59:56 +0000 Date: Fri, 20 Nov 2020 15:59:56 +0000 From: Matthew Wilcox To: Christoph Hellwig Cc: Jan Kara , Jens Axboe , Tejun Heo , Josef Bacik , Konrad Rzeszutek Wilk , Coly Li , Mike Snitzer , dm-devel@redhat.com, Richard Weinberger , Jan Kara , linux-block@vger.kernel.org, xen-devel@lists.xenproject.org, linux-bcache@vger.kernel.org, linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH 14/20] block: remove the nr_sects field in struct hd_struct Message-ID: <20201120155956.GB4327@casper.infradead.org> References: <20201118084800.2339180-1-hch@lst.de> <20201118084800.2339180-15-hch@lst.de> <20201119120525.GW1981@quack2.suse.cz> <20201120090820.GD21715@lst.de> <20201120112121.GB15537@quack2.suse.cz> <20201120153253.GA18990@lst.de> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201120153253.GA18990@lst.de> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Fri, Nov 20, 2020 at 04:32:53PM +0100, Christoph Hellwig wrote: > On Fri, Nov 20, 2020 at 12:21:21PM +0100, Jan Kara wrote: > > > > AFAICT bd_size_lock is pointless after these changes so we can just remove > > > > it? > > > > > > I don't think it is, as reuqiring bd_mutex for size updates leads to > > > rather awkward lock ordering problems. > > > > OK, let me ask differently: What is bd_size_lock protecting now? Ah, I see, > > on 32-bit it is needed to prevent torn writes to i_size, right? > > Exactly. In theory we could skip it for 64-bit, but as updating the > size isn't a fast path, and struct block_device isn't super size critical > I'd rather keep the same code for 32 vs 64-bit builds. Is it better to switch to i_size_write() / i_size_read()?