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=-15.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_SANE_1 autolearn=ham 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 A89E9C433DB for ; Tue, 16 Mar 2021 10:28:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6EB1265026 for ; Tue, 16 Mar 2021 10:28:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S235301AbhCPK1u (ORCPT ); Tue, 16 Mar 2021 06:27:50 -0400 Received: from mx2.suse.de ([195.135.220.15]:43780 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234838AbhCPK1k (ORCPT ); Tue, 16 Mar 2021 06:27:40 -0400 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 0DD05AD74; Tue, 16 Mar 2021 10:27:39 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id 833E2DA6E2; Tue, 16 Mar 2021 11:25:37 +0100 (CET) Date: Tue, 16 Mar 2021 11:25:37 +0100 From: David Sterba To: Anand Jain Cc: Qu Wenruo , dsterba@suse.cz, Qu Wenruo , linux-btrfs@vger.kernel.org Subject: Re: [PATCH v2 01/15] btrfs: add sysfs interface for supported sectorsize Message-ID: <20210316102537.GG7604@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Anand Jain , Qu Wenruo , Qu Wenruo , linux-btrfs@vger.kernel.org References: <20210310090833.105015-1-wqu@suse.com> <20210310090833.105015-2-wqu@suse.com> <61c2ba18-c3de-a67f-046f-1f315500c8c8@oracle.com> <59a9ee34-1893-a642-2a00-8cc42ec7a31f@gmx.com> <20210315184414.GZ7604@twin.jikos.cz> <57e0fbcc-a8db-a821-5948-fb048f426dc8@gmx.com> <82e16fe9-cf79-fb5e-2863-d9f6cc73adbc@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <82e16fe9-cf79-fb5e-2863-d9f6cc73adbc@oracle.com> User-Agent: Mutt/1.5.23.1-rc1 (2014-03-12) Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On Tue, Mar 16, 2021 at 08:10:13AM +0800, Anand Jain wrote: > > > On 16/03/2021 08:05, Qu Wenruo wrote: > > > > > > On 2021/3/16 上午2:44, David Sterba wrote: > >> On Mon, Mar 15, 2021 at 08:39:31PM +0800, Qu Wenruo wrote: > >>> > >>> > >>> On 2021/3/15 下午7:59, Anand Jain wrote: > >>>> On 10/03/2021 17:08, Qu Wenruo wrote: > >>>>> Add extra sysfs interface features/supported_ro_sectorsize and > >>>>> features/supported_rw_sectorsize to indicate subpage support. > >>>>> > >>>>> Currently for supported_rw_sectorsize all architectures only have > >>>>> their > >>>>> PAGE_SIZE listed. > >>>>> > >>>>> While for supported_ro_sectorsize, for systems with 64K page size, 4K > >>>>> sectorsize is also supported. > >>>>> > >>>>> This new sysfs interface would help mkfs.btrfs to do more accurate > >>>>> warning. > >>>>> > >>>>> Signed-off-by: Qu Wenruo > >>>>> --- > >>>> > >>>> Changes looks good. Nit below... > >>>> And maybe it is a good idea to wait for other comments before reroll. > >>>> > >>>>>    fs/btrfs/sysfs.c | 34 ++++++++++++++++++++++++++++++++++ > >>>>>    1 file changed, 34 insertions(+) > >>>>> > >>>>> diff --git a/fs/btrfs/sysfs.c b/fs/btrfs/sysfs.c > >>>>> index 6eb1c50fa98c..3ef419899472 100644 > >>>>> --- a/fs/btrfs/sysfs.c > >>>>> +++ b/fs/btrfs/sysfs.c > >>>>> @@ -360,11 +360,45 @@ static ssize_t > >>>>> supported_rescue_options_show(struct kobject *kobj, > >>>>>    BTRFS_ATTR(static_feature, supported_rescue_options, > >>>>>           supported_rescue_options_show); > >>>>> +static ssize_t supported_ro_sectorsize_show(struct kobject *kobj, > >>>>> +                        struct kobj_attribute *a, > >>>>> +                        char *buf) > >>>>> +{ > >>>>> +    ssize_t ret = 0; > >>>>> +    int i = 0; > >>>> > >>>>    Drop variable i, as ret can be used instead of 'i'. > >>>> > >>>>> + > >>>>> +    /* For 64K page size, 4K sector size is supported */ > >>>>> +    if (PAGE_SIZE == SZ_64K) { > >>>>> +        ret += scnprintf(buf + ret, PAGE_SIZE - ret, "%u", SZ_4K); > >>>>> +        i++; > >>>>> +    } > >>>>> +    /* Other than above subpage, only support PAGE_SIZE as sectorsize > >>>>> yet */ > >>>>> +    ret += scnprintf(buf + ret, PAGE_SIZE - ret, "%s%lu\n", > >>>> > >>>>> +             (i ? " " : ""), PAGE_SIZE); > >>>>                             ^ret > >>>> > >>>>> +    return ret; > >>>>> +} > >>>>> +BTRFS_ATTR(static_feature, supported_ro_sectorsize, > >>>>> +       supported_ro_sectorsize_show); > >>>>> + > >>>>> +static ssize_t supported_rw_sectorsize_show(struct kobject *kobj, > >>>>> +                        struct kobj_attribute *a, > >>>>> +                        char *buf) > >>>>> +{ > >>>>> +    ssize_t ret = 0; > >>>>> + > >>>>> +    /* Only PAGE_SIZE as sectorsize is supported */ > >>>>> +    ret += scnprintf(buf + ret, PAGE_SIZE - ret, "%lu\n", PAGE_SIZE); > >>>>> +    return ret; > >>>>> +} > >>>>> +BTRFS_ATTR(static_feature, supported_rw_sectorsize, > >>>>> +       supported_rw_sectorsize_show); > >>>> > >>>>    Why not merge supported_ro_sectorsize and supported_rw_sectorsize > >>>>    and show both in two lines... > >>>>    For example: > >>>>      cat supported_sectorsizes > >>>>      ro: 4096 65536 > >>>>      rw: 65536 > >>> > >>> If merged, btrfs-progs needs to do line number check before doing string > >>> matching. > >> > >> The sysfs files should do one value per file. > >> > >>> Although I doubt the usefulness for supported_ro_sectorsize, as the > >>> window for RO support without RW support should not be that large. > >>> (Current RW passes most generic test cases, and the remaining failures > >>> are very limited) > >>> > >>> Thus I can merged them into supported_sectorsize, and only report > >>> sectorsize we can do RW as supported. > >> > >> In that case one file with the list of supported values is a better > >> option. The main point is to have full RW support, until then it's > >> interesting only for developers and they know what to expect. > >> > > > > Indeed only full RW support makes sense. > > > Makes sense to me. > > > BTW, any comment on the file name? If no problem I would just use > > "supported_sectorsize" in next update. > > supported_sectorsizes (plural) is better IMO. Yeah pluar is consistent with what we have now, eg. supported_checksums