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=-2.2 required=3.0 tests=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 1DED6C3A589 for ; Tue, 20 Aug 2019 13:05:27 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E9CF822DA7 for ; Tue, 20 Aug 2019 13:05:26 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729298AbfHTNF0 (ORCPT ); Tue, 20 Aug 2019 09:05:26 -0400 Received: from mx2.suse.de ([195.135.220.15]:49964 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1727006AbfHTNFZ (ORCPT ); Tue, 20 Aug 2019 09:05:25 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id 76112AE42; Tue, 20 Aug 2019 13:05:24 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 56B46DA7DA; Tue, 20 Aug 2019 15:05:50 +0200 (CEST) Date: Tue, 20 Aug 2019 15:05:50 +0200 From: David Sterba To: Naohiro Aota Cc: Anand Jain , Chris Mason , David Sterba , Hannes Reinecke , Nikolay Borisov , Johannes Thumshirn , Josef Bacik , "linux-btrfs@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , Damien Le Moal , Matias Bjorling Subject: Re: [PATCH v3 03/27] btrfs: Check and enable HMZONED mode Message-ID: <20190820130419.GP24086@suse.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Naohiro Aota , Anand Jain , Chris Mason , David Sterba , Hannes Reinecke , Nikolay Borisov , Johannes Thumshirn , Josef Bacik , "linux-btrfs@vger.kernel.org" , "linux-fsdevel@vger.kernel.org" , Damien Le Moal , Matias Bjorling References: <20190808093038.4163421-1-naohiro.aota@wdc.com> <20190808093038.4163421-4-naohiro.aota@wdc.com> <86ef7944-0029-3d61-0ae3-874015726751@oracle.com> <20190820050737.ngyaamjkdmzvhlqj@naota.dhcp.fujisawa.hgst.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190820050737.ngyaamjkdmzvhlqj@naota.dhcp.fujisawa.hgst.com> User-Agent: Mutt/1.5.23.1 (2014-03-12) Sender: linux-btrfs-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Tue, Aug 20, 2019 at 02:07:37PM +0900, Naohiro Aota wrote: > >>>>cannot be located over sequential zones and there is no guarantees that the > >>>>device will have enough conventional zones to store this cache. Resolve > >>>>this problem by disabling completely the space cache. This does not > >>>>introduces any problems with sequential block groups: all the free space is > >>>>located after the allocation pointer and no free space before the pointer. > >>>>There is no need to have such cache. > >>>> > >>>>For the same reason, NODATACOW is also disabled. > >>>> > >>>>Also INODE_MAP_CACHE is also disabled to avoid preallocation in the > >>>>INODE_MAP_CACHE inode. > >>> > >>> A list of incompatibility features with zoned devices. This need better > >>> documentation, may be a table and its reason is better. > >> > >>Are you referring to the format of the commit message itself ? Or would you like > >>to see a documentation added to Documentation/filesystems/btrfs.txt ? > > > > Documenting in the commit change log is fine. But it can be better > > documented in a listed format as it looks like we have a list of > > features which will be incompatible with zoned devices. > > > >more below.. > > Sure. I will add a table in the next version. > > btrfs.txt seems not to have much there. We don't use the in-kernel documentation, it's either the wiki or the manual pages in btrfs-progs. The section 5 page contains some generic topics, eg. the swapfile limitations are there.