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=-5.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 A4E6CC433DB for ; Wed, 10 Feb 2021 20:01:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 67C7264E31 for ; Wed, 10 Feb 2021 20:01:24 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232854AbhBJUBW (ORCPT ); Wed, 10 Feb 2021 15:01:22 -0500 Received: from mx2.suse.de ([195.135.220.15]:59344 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232742AbhBJUBK (ORCPT ); Wed, 10 Feb 2021 15:01:10 -0500 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.221.27]) by mx2.suse.de (Postfix) with ESMTP id 8C80FAE8A; Wed, 10 Feb 2021 20:00:23 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id BAC46DA6E9; Wed, 10 Feb 2021 20:58:29 +0100 (CET) Date: Wed, 10 Feb 2021 20:58:29 +0100 From: David Sterba To: Naohiro Aota Cc: linux-btrfs@vger.kernel.org, dsterba@suse.com, hare@suse.com, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v15 00/42] btrfs: zoned block device support Message-ID: <20210210195829.GW1993@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Naohiro Aota , linux-btrfs@vger.kernel.org, dsterba@suse.com, hare@suse.com, linux-fsdevel@vger.kernel.org References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Thu, Feb 04, 2021 at 07:21:39PM +0900, Naohiro Aota wrote: > This series adds zoned block device support to btrfs. Some of the patches > in the previous series are already merged as preparation patches. Moved from for-next to misc-next. > * Log-structured superblock > > Superblock (and its copies) is the only data structure in btrfs which > has a fixed location on a device. Since we cannot overwrite in a > sequential write required zone, we cannot place superblock in the > zone. > > This series implements superblock log writing. It uses two zones as a > circular buffer to write updated superblocks. Once the first zone is filled > up, start writing into the second zone. The first zone will be reset once > both zones are filled. We can determine the postion of the latest > superblock by reading the write pointer information from a device. About that, in this patchset it's still leaving superblock at the fixed zone number while we want it at a fixed location, spanning 2 zones regardless of their size.