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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 9CBBFC433F5 for ; Mon, 22 Nov 2021 15:20:33 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S233367AbhKVPXj (ORCPT ); Mon, 22 Nov 2021 10:23:39 -0500 Received: from smtp-out2.suse.de ([195.135.220.29]:41150 "EHLO smtp-out2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232194AbhKVPXi (ORCPT ); Mon, 22 Nov 2021 10:23:38 -0500 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 1D8131FD49; Mon, 22 Nov 2021 15:20:31 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=suse.com; s=susede1; t=1637594431; 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=U5T9jhkRhYh+Z/Z8qjWyokv7SQ3/4Trzr1/UWd5yh1I=; b=EaBpGuRDQmhav9pXuF5vb+9QaBqYS1xozKTu2A5uK8qReo8oKPQJn3u+WiXoTh19PAqrsW yyTakig5VRmS3/CpJC+6RJ3j7E+6+ogezjzkMYKjtx/flCbldPWjG2cEnCmhDqaWp8pxKl E6Q12MySAsCdJ3gPnBTja1ghcs+P/co= 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 BBA4913B44; Mon, 22 Nov 2021 15:20:30 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id GiT7Kj61m2FdDwAAMHmgww (envelope-from ); Mon, 22 Nov 2021 15:20:30 +0000 Subject: Re: [PATCH v2] btrfs-progs: filesystem: du: skip file that permission denied To: Sidong Yang Cc: Graham Cobb , linux-btrfs , David Sterba References: <20211121151556.8874-1-realwakka@gmail.com> <09d229c6-ae30-4453-c9d4-39109f032b99@suse.com> <20211122083240.GB8836@realwakka> <0a7ce0b1-300c-233b-d844-012dfc771efe@suse.com> <20211122151027.GA10523@realwakka> From: Nikolay Borisov Message-ID: Date: Mon, 22 Nov 2021 17:20:30 +0200 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101 Thunderbird/78.13.0 MIME-Version: 1.0 In-Reply-To: <20211122151027.GA10523@realwakka> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 22.11.21 г. 17:10, Sidong Yang wrote: > On Mon, Nov 22, 2021 at 12:57:18PM +0200, Nikolay Borisov wrote: >> >> >> On 22.11.21 г. 11:53, Graham Cobb wrote: >>> >>> On 22/11/2021 09:32, Nikolay Borisov wrote: >>>> >>>> >>>> On 22.11.21 г. 10:32, Sidong Yang wrote: >>>>> On Mon, Nov 22, 2021 at 09:20:00AM +0200, Nikolay Borisov wrote: >>>>>> >>>>>> >>>>>> On 21.11.21 г. 17:15, Sidong Yang wrote: >>>>>>> This patch handles issue #421. Filesystem du command fails and exit >>>>>>> when it access file that has permission denied. But it can continue the >>>>>>> command except the files. This patch recovers ret value when permission >>>>>>> denied. >>>>>>> >>>>>>> Signed-off-by: Sidong Yang >>>>>> >>>>>> >>>>>> The code itself is fine so : >>>>>> >>>>>> >>>>>> Reviewed-by: Nikolay Borisov >>>>>> >>>>>> >>>>>> OTOH when I looked at the code rather than just the patch I can't help >>>>>> but wonder shouldn't we actually structure this the way you initially >>>>>> proposed but also add a debug output along the lines of "skipping >>>>>> file/dir XXXX due to permission denied", otherwise users might not be >>>>>> able to account for some space and they can possibly wonder that >>>>>> something is wrong with btrfs fi du command. >>>>> >>>>> You mean that it would be better that print some debug message than >>>>> skipping silently. I agree. So I would add this code in condition. >>>>> >>>>> fprintf(stderr, "skipping file/dir: %s : %m\n", entry->d_name); >>>>> >>>>> I think it's okay that it prints when ENOTTY occurs. Is this code what >>>>> you meant? >>>> >>>> >>>> I meant to print only if we have EACCESS, but now that I think about it, >>>> printing something when we have a non-fatal error and simply skipping >>>> some dirs/files makes sense. OTOH printing it by default might be too >>>> verbose so perhaps usuing a pr_verbose call would be more appropriate. >>>> >>>> This is one of those things which don't have a clear-cut answers so it's >>>> useful to get as many perspective as possible to arrive at some workable >>>> solution to a wider number of people. >>> >>> I must admit I just assumed it worked the same way as /bin/du. I have >>> just created an inaccessible directory and got: >>> >>> $ du -sh ~ >>> du: cannot read directory '/home/cobb/permtest': Permission denied >>> 61G /home/cobb >>> >>> And when the directory was accessible but the file in it was not, I got: >>> >>> $ du -sh ~ >>> du: cannot access '/home/cobb/permtest/file': Permission denied >>> 61G /home/cobb >>> >>> In other words, I think any error should be printed but the error is >>> then skipped and the du continues. No need to tell people the file is >>> being skipped - that is obvious. But the error must be printed by >>> default (if there are really cases where the error should not be printed >>> but reasons not to redirect stderr to /dev/null then add an option to >>> suppress printing it). >>> >>> Just my opinion. >> >> >> That actually works for me, I'd rather btrfs be as consistent as >> possible and not give surprises to users. So just mimicking what an >> omnipresent tool does is as good as it gets :) > > Yeah, I understood that any error should be printed but no need to print > that it is skipped. I agree. If so, I think the code that print error > message should like below. > > fprintf(stderr, "failed to walk dir/file: %s: %m\n", entry->d_name); > > I agreed that btrfs command should be like "du" command that familiar > with users. I wonder if I understood it well. > > If so, I think it would be better that use switch-case than if-else. let's be inline with du: fprintf(stderr, "cannot access: '%s:' %m\n", entry->d_name); Also %m works with the error in errno and in this case the error is in ret, so you'd need to set errno to ret. >> >> >>> >>> Graham >>> >