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=-15.3 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,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 4BE94C433E9 for ; Mon, 15 Mar 2021 18:47:22 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 18CF564F3F for ; Mon, 15 Mar 2021 18:47:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231811AbhCOSqt (ORCPT ); Mon, 15 Mar 2021 14:46:49 -0400 Received: from mx2.suse.de ([195.135.220.15]:44686 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232554AbhCOSqR (ORCPT ); Mon, 15 Mar 2021 14:46:17 -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 2DF8AAE8F; Mon, 15 Mar 2021 18:46:16 +0000 (UTC) Received: by ds.suse.cz (Postfix, from userid 10065) id E4BA3DA6E2; Mon, 15 Mar 2021 19:44:14 +0100 (CET) Date: Mon, 15 Mar 2021 19:44:14 +0100 From: David Sterba To: Qu Wenruo Cc: Anand Jain , Qu Wenruo , linux-btrfs@vger.kernel.org Subject: Re: [PATCH v2 01/15] btrfs: add sysfs interface for supported sectorsize Message-ID: <20210315184414.GZ7604@twin.jikos.cz> Reply-To: dsterba@suse.cz Mail-Followup-To: dsterba@suse.cz, Qu Wenruo , Anand Jain , 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> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <59a9ee34-1893-a642-2a00-8cc42ec7a31f@gmx.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 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.