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=-7.3 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, NICE_REPLY_A,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 B47F1C433F5 for ; Thu, 23 Sep 2021 07:13:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 941C861050 for ; Thu, 23 Sep 2021 07:13:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239549AbhIWHP3 (ORCPT ); Thu, 23 Sep 2021 03:15:29 -0400 Received: from smtp-out2.suse.de ([195.135.220.29]:37218 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234343AbhIWHP3 (ORCPT ); Thu, 23 Sep 2021 03:15:29 -0400 Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by smtp-out2.suse.de (Postfix) with ESMTPS id C012920278; Thu, 23 Sep 2021 07:13:56 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_rsa; t=1632381236; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QY7WPyKmhlWy7yhhaiksEFQ2o0DzPZj/w9H1QqhuKSk=; b=TCLmHYAUJbBa25xCbUStdXDCFQLpDhOEySKAa0C/wKkmvol8THH6kNOvtm4kXMH2E3J8+j 9AaGqDrqopZEGzTtsTCutCElnq2ezUVRgEgXXLLoMJDit+V7v9aOmo/N9RIQPX7fC9ld6r lVSSHmNLSAsoYl4PZGAWTZG1dn0FGA0= DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=suse.de; s=susede2_ed25519; t=1632381236; h=from:from:reply-to:date:date:message-id:message-id:to:to:cc:cc: mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=QY7WPyKmhlWy7yhhaiksEFQ2o0DzPZj/w9H1QqhuKSk=; b=dUbcrPlGddRby7zrgkcuSNqKrOPPR66Anzv6Ad3RLQpBeQLL2CDO2cwrtPkPWXYrEfiH9u eg7ZCDqHtS3Vz+Ag== Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id 61C5C13DC4; Thu, 23 Sep 2021 07:13:54 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id u+DLDTIpTGHcdAAAMHmgww (envelope-from ); Thu, 23 Sep 2021 07:13:54 +0000 Subject: Re: Too large badblocks sysfs file (was: [PATCH v3 0/7] badblocks improvement for multiple bad block ranges) To: Greg Kroah-Hartman Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-raid@vger.kernel.org, nvdimm@lists.linux.dev, antlists@youngman.org.uk, Dan Williams , Hannes Reinecke , Jens Axboe , NeilBrown , Richard Fan , Vishal L Verma , rafael@kernel.org References: <20210913163643.10233-1-colyli@suse.de> From: Coly Li Message-ID: <0a9f7fd9-a587-0152-118f-c61fe563f97f@suse.de> Date: Thu, 23 Sep 2021 15:13:52 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:78.0) Gecko/20100101 Thunderbird/78.14.0 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit Content-Language: en-US Precedence: bulk List-ID: X-Mailing-List: linux-raid@vger.kernel.org On 9/23/21 2:47 PM, Greg Kroah-Hartman wrote: > On Thu, Sep 23, 2021 at 02:14:12PM +0800, Coly Li wrote: >> On 9/23/21 2:08 PM, Greg Kroah-Hartman wrote: >>> On Thu, Sep 23, 2021 at 01:59:28PM +0800, Coly Li wrote: >>>> Hi all the kernel gurus, and folks in mailing lists, >>>> >>>> This is a question about exporting 4KB+ text information via sysfs >>>> interface. I need advice on how to handle the problem. >> Hi Greg, >> >> This is the code in mainline kernel for quite long time. > {sigh} > > What tools rely on this? If none, just don't add new stuff to the file > and work to create a new api instead. At least I know mdadm uses this sysfs interface for md raid component disks monitoring. It has been in mdadm for around 5 years. Yes you are right, let it be for existing sysfs interface to avoid breaking things. >>> Please do not do that. Seriously, that is not what sysfs is for, and is >>> an abuse of it. >>> >>> sysfs is for "one value per file" and should never even get close to a >>> 4kb limit. If it does, you are doing something really really wrong and >>> should just remove that sysfs file from the system and redesign your >>> api. >> I understand this. And what I addressed is the problem I need to fix. >> >> The code is there for almost 10 years, I just find it during my work on bad >> blocks API fixing. >> >> >>>> Recently I work on the bad blocks API (block/badblocks.c) improvement, there >>>> is a sysfs file to export the bad block ranges for me raid. E.g for a md >>>> raid1 device, file >>>>     /sys/block/md0/md/rd0/bad_blocks >>>> may contain the following text content, >>>>     64 32 >>>>    128 8 >>> Ick, again, that's not ok at all. sysfs files should never have to be >>> parsed like this. >> I cannot agree more with you. What I am asking for was ---- how to fix it ? > Best solution, come up with a new api. > > Worst solution, you are stuck with the existing file and I can show you > the "way out" of dealing with files larger than 4kb in sysfs that a > number of other apis are being forced to do as they grow over time. Now I am sure you are very probably not willing to accept the patches, even I know how to do that :-) > > But ideally, just drop ths api and make a new one please. OK, then I leave the existing things as what they are, avoid to make them worse. Thanks for your response. Coly Li