From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id D77DF6FB0; Tue, 5 Dec 2023 03:46:05 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.b="zyx3htMl" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 559ACC433C7; Tue, 5 Dec 2023 03:46:05 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1701747965; bh=VHA0Cy7CfoInslozdMx+oDGIez9VTYjR8KTuTCrTmrk=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=zyx3htMlPVKAAR5EYxS8RJMLWoN5qSbpCb70NrXuth3TvaBYapFwgfecdHZHAiI12 9obcQ5CJ1zgpuxPMfKgN/8dmbj6SwUoAHan2jxK9Y9USevvsxk+r68RBAqvCnQDtcJ WGEFRzcdB1DjBQuVnDrSspFzigzVUmp68ZKf+WzM= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Anand Jain , Qu Wenruo , David Sterba Subject: [PATCH 5.4 63/94] btrfs: add dmesg output for first mount and last unmount of a filesystem Date: Tue, 5 Dec 2023 12:17:31 +0900 Message-ID: <20231205031526.359703653@linuxfoundation.org> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20231205031522.815119918@linuxfoundation.org> References: <20231205031522.815119918@linuxfoundation.org> User-Agent: quilt/0.67 X-stable: review X-Patchwork-Hint: ignore Precedence: bulk X-Mailing-List: stable@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 5.4-stable review patch. If anyone has any objections, please let me know. ------------------ From: Qu Wenruo commit 2db313205f8b96eea467691917138d646bb50aef upstream. 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 own 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 directory /sys/fs// This is way more simple, 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. And since we're here, also add the output when mounting a filesystem for the first time for parity. A more fine grained monitoring of subvolume mounts should be done by another layer, like audit. Now mounting a btrfs with all default mkfs options would look like this: [81.906566] BTRFS info (device dm-8): first mount of filesystem 633b5c16-afe3-4b79-b195-138fe145e4f2 [81.907494] BTRFS info (device dm-8): using crc32c (crc32c-intel) checksum algorithm [81.908258] BTRFS info (device dm-8): using free space tree [81.912644] BTRFS info (device dm-8): auto enabling async discard [81.913277] BTRFS info (device dm-8): checking UUID tree [91.668256] BTRFS info (device dm-8): last unmount of filesystem 633b5c16-afe3-4b79-b195-138fe145e4f2 CC: stable@vger.kernel.org # 5.4+ Link: https://github.com/kdave/btrfs-progs/issues/689 Reviewed-by: Anand Jain Signed-off-by: Qu Wenruo Reviewed-by: David Sterba [ update changelog ] Signed-off-by: David Sterba Signed-off-by: Greg Kroah-Hartman --- fs/btrfs/disk-io.c | 1 + fs/btrfs/super.c | 5 ++++- 2 files changed, 5 insertions(+), 1 deletion(-) --- a/fs/btrfs/disk-io.c +++ b/fs/btrfs/disk-io.c @@ -2829,6 +2829,7 @@ int open_ctree(struct super_block *sb, goto fail_alloc; } + btrfs_info(fs_info, "first mount of filesystem %pU", disk_super->fsid); /* * Verify the type first, if that or the checksum value are * corrupted, we'll find out --- a/fs/btrfs/super.c +++ b/fs/btrfs/super.c @@ -291,7 +291,10 @@ void __btrfs_panic(struct btrfs_fs_info static void btrfs_put_super(struct super_block *sb) { - close_ctree(btrfs_sb(sb)); + struct btrfs_fs_info *fs_info = btrfs_sb(sb); + + btrfs_info(fs_info, "last unmount of filesystem %pU", fs_info->fs_devices->fsid); + close_ctree(fs_info); } enum {