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 B2341C4332F for ; Fri, 3 Nov 2023 05:02:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229481AbjKCFCX (ORCPT ); Fri, 3 Nov 2023 01:02:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49238 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229436AbjKCFCV (ORCPT ); Fri, 3 Nov 2023 01:02:21 -0400 Received: from mout.gmx.net (mout.gmx.net [212.227.15.15]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 852861A4 for ; Thu, 2 Nov 2023 22:02:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=gmx.com; s=s31663417; t=1698987727; x=1699592527; i=quwenruo.btrfs@gmx.com; bh=n5aj+6nWMYyTT4cCrUcxvXrfKSVl5+0sa6WA8CtUi8s=; h=X-UI-Sender-Class:Date:Subject:To:Cc:References:From: In-Reply-To; b=soOqcRgxCEVHE1Hb6fgi6A2MgNQQQb/mcSqVvCItxGYm9WkfdIjdDiF0EkdNMzSN /MdBGF2gWyxr7YPZ4V5PqM85gD8eldkIDrpGciiqaALlIJJoHNPVQJyHNhFXjm6CL IZPr4plCTIgIbjbJt1YNcsMPILOkgmxe8lK/l/PivZ6f5Is21KZtc0LvJzb3u+VOn NrNpTYMa48uLLoY6dLmHG+BnaO4w4to6Rsn5yzW1H8iMbnbKNL0++mwGxv363ttlF ZkRaaaCiOM9LCSVZFtO+ofC2hx64IsuCKqjyn1ejtK0rN+oYGy0f7KqchoHRs8aSl UaSzHzpKRb2PeEq9wA== X-UI-Sender-Class: 724b4f7f-cbec-4199-ad4e-598c01a50d3a Received: from [172.16.0.117] ([122.151.37.21]) by mail.gmx.net (mrgmx005 [212.227.17.184]) with ESMTPSA (Nemesis) id 1MC30Z-1r8uGo0ehZ-00CUxa; Fri, 03 Nov 2023 06:02:07 +0100 Message-ID: Date: Fri, 3 Nov 2023 15:32:03 +1030 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] btrfs: add dmesg output when mounting and unmounting Content-Language: en-US To: dsterba@suse.cz, Anand Jain Cc: Qu Wenruo , linux-btrfs@vger.kernel.org References: <215e7eea95459d1b0cc4fd9ce522dc7c8f5d4e02.1698873846.git.wqu@suse.com> <18fda4f8-8f3c-4dd1-8aca-667726e278df@oracle.com> <20231102201818.GI11264@twin.jikos.cz> From: Qu Wenruo Autocrypt: addr=quwenruo.btrfs@gmx.com; keydata= xsBNBFnVga8BCACyhFP3ExcTIuB73jDIBA/vSoYcTyysFQzPvez64TUSCv1SgXEByR7fju3o 8RfaWuHCnkkea5luuTZMqfgTXrun2dqNVYDNOV6RIVrc4YuG20yhC1epnV55fJCThqij0MRL 1NxPKXIlEdHvN0Kov3CtWA+R1iNN0RCeVun7rmOrrjBK573aWC5sgP7YsBOLK79H3tmUtz6b 9Imuj0ZyEsa76Xg9PX9Hn2myKj1hfWGS+5og9Va4hrwQC8ipjXik6NKR5GDV+hOZkktU81G5 gkQtGB9jOAYRs86QG/b7PtIlbd3+pppT0gaS+wvwMs8cuNG+Pu6KO1oC4jgdseFLu7NpABEB AAHNIlF1IFdlbnJ1byA8cXV3ZW5ydW8uYnRyZnNAZ214LmNvbT7CwJQEEwEIAD4CGwMFCwkI BwIGFQgJCgsCBBYCAwECHgECF4AWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCY00iVQUJDToH pgAKCRDCPZHzoSX+qNKACACkjDLzCvcFuDlgqCiS4ajHAo6twGra3uGgY2klo3S4JespWifr BLPPak74oOShqNZ8yWzB1Bkz1u93Ifx3c3H0r2vLWrImoP5eQdymVqMWmDAq+sV1Koyt8gXQ XPD2jQCrfR9nUuV1F3Z4Lgo+6I5LjuXBVEayFdz/VYK63+YLEAlSowCF72Lkz06TmaI0XMyj jgRNGM2MRgfxbprCcsgUypaDfmhY2nrhIzPUICURfp9t/65+/PLlV4nYs+DtSwPyNjkPX72+ LdyIdY+BqS8cZbPG5spCyJIlZonADojLDYQq4QnufARU51zyVjzTXMg5gAttDZwTH+8LbNI4 mm2YzsBNBFnVga8BCACqU+th4Esy/c8BnvliFAjAfpzhI1wH76FD1MJPmAhA3DnX5JDORcga CbPEwhLj1xlwTgpeT+QfDmGJ5B5BlrrQFZVE1fChEjiJvyiSAO4yQPkrPVYTI7Xj34FnscPj /IrRUUka68MlHxPtFnAHr25VIuOS41lmYKYNwPNLRz9Ik6DmeTG3WJO2BQRNvXA0pXrJH1fN GSsRb+pKEKHKtL1803x71zQxCwLh+zLP1iXHVM5j8gX9zqupigQR/Cel2XPS44zWcDW8r7B0 q1eW4Jrv0x19p4P923voqn+joIAostyNTUjCeSrUdKth9jcdlam9X2DziA/DHDFfS5eq4fEv ABEBAAHCwHwEGAEIACYCGwwWIQQt33LlpaVbqJ2qQuHCPZHzoSX+qAUCY00ibgUJDToHvwAK CRDCPZHzoSX+qK6vB/9yyZlsS+ijtsvwYDjGA2WhVhN07Xa5SBBvGCAycyGGzSMkOJcOtUUf tD+ADyrLbLuVSfRN1ke738UojphwkSFj4t9scG5A+U8GgOZtrlYOsY2+cG3R5vjoXUgXMP37 INfWh0KbJodf0G48xouesn08cbfUdlphSMXujCA8y5TcNyRuNv2q5Nizl8sKhUZzh4BascoK DChBuznBsucCTAGrwPgG4/ul6HnWE8DipMKvkV9ob1xJS2W4WJRPp6QdVrBWJ9cCdtpR6GbL iQi22uZXoSPv/0oUrGU+U5X4IvdnvT+8viPzszL5wXswJZfqfy8tmHM85yjObVdIG6AlnrrD In-Reply-To: <20231102201818.GI11264@twin.jikos.cz> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: quoted-printable X-Provags-ID: V03:K1:+ecuHnY5R6e2kvZmsIs4nVNyHdllnvGueB2Ni3F5DG6QGLgPLPU ZJQjf4iiAOn2snXS8E92awtNS9vrI11bIirCbMyvma8+CZ5wGxPh6uID3kF4UMzMs8YQ0nQ QSZqqRxtT1wf5srMQ+ggAGqo0xBT37bIFzrkU2KegZd7PazX1Y8xbPfJk8O6TJofDS6ujaf SplHq23owfm+WmzASZzIQ== UI-OutboundReport: notjunk:1;M01:P0:ks+RWRKQFP8=;lALiZj1uCWKf9MZjYHsYNak6ABP pfxMFMi6kwO/p4A5Hw2/3SkpXo2n2tpDRhohWOhuHTfsR6wGg1lkU8KP9e7jIKwlGdSVhqi2Q M++E4FPEtHqO1C2lpQIvO1LcOkYTD4rwFkVG5e1pZvzQA3Kjc68Iv5HwcH8LISFAbW7EKntOx qMesfD29c92HCXqR92s4hMBVLqzkzTtFRpuK/wzc2Gb4C0PoN36mEC7gUh6x5EDYC4mzWccz2 CIhohPFuXefPVPNKWLAjkZyErXlcftskezeESqu7JckM8+Y/Ls7ZGJ7rROZDo9VWfV6ePpibb jNVJggHr6NrxZk7qdXFtnllNhwmrIhtkcDPyB8OCC8ymBtYUUDsm0Uvcmv/Fi/6ip3VuZ6CU3 /yp23SIRJR5KU0hqBPNvB9zGbPt7a2fsEM1JdwPcvM2ppdY1+IqrHtc5PEWwGtNwXtzOnaqxf Ig/1istPWLZx5WrsMw9YaWzcZZaOH6UqTzNgvwMy091pZ9mlWOjV6q3ZKNQ5SN93mTp8l8j9P MrqgUvczN/nnopKrIl/lU07hWKeOlTdPxDa+hzr5ieP61f3iVMCC3B+vLE8x4snfeYyjf7ihk a9NJ2BG6I4zg0RY0de74szNkOR+Qtt+62E2mazkqqyFvrKr2/XzupikdPn6zmIvcFL5gsTUl2 d6ALmxgBEwMXatlUFH4jbUmFSZAylhL5IiPymb8TZW4R3IGx9kOwefPp7qPvrvIpI8q3Y3pPy K67LgqcZnBmBwPd7B1AoswQAof8hNzEBkImimCG/YSdIxYBZV5dEbDdcO6nAsIBRWDD+ukk2B /zCTjc/QdoZQK9mQVFm7YkavPKsMPU/4KTLWjHSbuLxvyBMKqdBkSW986VJfOaljTcPvF0FkB H+F8ZdMQUQwYJlCuniNBF8dydRL5v5wZV7ukwANfiW7BMTI05nbVLBag4jxLDmggpNuEnNhY8 xLAeCvAbQX39T43Ar9x7xZOCoxQ= Precedence: bulk List-ID: X-Mailing-List: linux-btrfs@vger.kernel.org On 2023/11/3 06:48, David Sterba wrote: > On Thu, Nov 02, 2023 at 09:16:19AM +0800, Anand Jain wrote: >> On 11/2/23 05:24, Qu Wenruo wrote: >>> There is a feature request to add dmesg output when unmounting a btrfs= . >>> >>> There are several alternative methods to do the same thing, but with >>> their problems: >>> >>> - Use eBPF to watch btrfs_put_super()/open_ctree() >>> Not end user friendly, they have to dip their head into the source >>> code. >>> >>> - Watch for /sys/fs// >>> This is way more simpler, but still requires some simple device ->= uuid >>> lookups. >>> And a script needs to use inotify to watch /sys/fs/. >>> >> >> >>> Compared to all these, directly outputting the information into dmesg >>> would be the most simple one, with both device and UUID included. >>> >> >> Well, I submitted a patch for this in 2017, but I'm not sure why it >> wasn't integrated or commented. >> >> https://lore.kernel.org/linux-btrfs/3352043d-dbb1-0055-f50a-c91ca43aff1= d@oracle.com/ > > I think you sent it more than once and that I replied, messages about > mounting each subvolume (as in your patch) seem to be duplicating what > eg. audit or some policy layer should do. The same comment is in the > github issue. > > The patch here and the request is to track only the first and last mount > of the same filesystem with a bit different use case, eg. properly > waiting until lazy umount finishe, or in container environments to be > sure that the last mount is gone. > > The suggested waiting on /sys/fs/btrfs/UUID could eventually wrapped in > a subcommand, for conveniencie. My bad, I didn't realize until I crafted the `btrfs monitor watch` command= . Inotify just doesn't work on sysfs.... So I believe for now, the patch is the best way to go, unless we want to something like checking the sysfs every second... Thanks, Qu