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=-10.2 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,MAILING_LIST_MULTI, NICE_REPLY_A,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 D07D7C63798 for ; Wed, 18 Nov 2020 09:55:50 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 1C84F22210 for ; Wed, 18 Nov 2020 09:55:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 1C84F22210 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=suse.de Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id F37E16B0036; Wed, 18 Nov 2020 04:55:48 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id EE7066B0068; Wed, 18 Nov 2020 04:55:48 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id E003E6B006C; Wed, 18 Nov 2020 04:55:48 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0037.hostedemail.com [216.40.44.37]) by kanga.kvack.org (Postfix) with ESMTP id B14186B0036 for ; Wed, 18 Nov 2020 04:55:48 -0500 (EST) Received: from smtpin07.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 6107B180AD822 for ; Wed, 18 Nov 2020 09:55:48 +0000 (UTC) X-FDA: 77497082376.07.salt12_5a08de427339 Received: from filter.hostedemail.com (10.5.16.251.rfc1918.com [10.5.16.251]) by smtpin07.hostedemail.com (Postfix) with ESMTP id 45AF61804E955 for ; Wed, 18 Nov 2020 09:55:48 +0000 (UTC) X-HE-Tag: salt12_5a08de427339 X-Filterd-Recvd-Size: 2784 Received: from mx2.suse.de (mx2.suse.de [195.135.220.15]) by imf10.hostedemail.com (Postfix) with ESMTP for ; Wed, 18 Nov 2020 09:55:47 +0000 (UTC) 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 8DCB7ABDE; Wed, 18 Nov 2020 09:55:46 +0000 (UTC) To: Greg KH Cc: Christoph Hellwig , Jens Axboe , Tejun Heo , Josef Bacik , Konrad Rzeszutek Wilk , Mike Snitzer , dm-devel@redhat.com, Richard Weinberger , Jan Kara , linux-block@vger.kernel.org, xen-devel@lists.xenproject.org, linux-bcache@vger.kernel.org, linux-mtd@lists.infradead.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org References: <20201118084800.2339180-1-hch@lst.de> <20201118084800.2339180-20-hch@lst.de> From: Coly Li Subject: Re: [PATCH 19/20] bcache: remove a superflous lookup_bdev all Message-ID: <24c818c2-6aba-098c-0c73-0a5081175c06@suse.de> Date: Wed, 18 Nov 2020 17:55:38 +0800 User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.16; rv:78.0) Gecko/20100101 Thunderbird/78.4.3 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: quoted-printable X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 11/18/20 5:10 PM, Greg KH wrote: > On Wed, Nov 18, 2020 at 04:54:51PM +0800, Coly Li wrote: >> On 11/18/20 4:47 PM, Christoph Hellwig wrote: >>> Don't bother to call lookup_bdev for just a slightly different error >>> message without any functional change. >>> >>> Signed-off-by: Christoph Hellwig ist >> >> Hi Christoph, >> >> NACK. This removing error message is frequently triggered and observed= , >> and distinct a busy device and an already registered device is importa= nt >> (the first one is critical error and second one is not). >> >> Remove such error message will be a functional regression. >=20 > What normal operation causes this error message to be emitted? And wha= t > can a user do with it? When there was bug and the caching or backing device was not unregistered successfully, people could see "device busy"; and if it was because the device registered again, it could be "already registered". Without the different message, people may think the device is always busy but indeed it isn't. he motivation of the patch is OK to me, but we need to make the logical consistent, otherwise we will have similar bug report for bogus warning dmesg from bcache users in soon future. Coly Li