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 C31A520409D; Wed, 13 Nov 2024 13:45:08 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731505508; cv=none; b=VZDlLr3lJxLEwFDxx3b/6YOqMyW5j3g/fE7Ap7vwxQwx8xngqsViibryWLa5a75FGGiDw46Jic9Q4VMs8BQIk62ABPAk99Fu5iD+UwAif12jiSOZr+0DB2R+5x3DYeaR+nYA84GVQS7gR/vy+emc46zA3BoT20OZC3TDZw6V2jU= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1731505508; c=relaxed/simple; bh=463bUkz/5tCXUXgaLe+/YHfvDlUVaS5zOq/K3ekFYDA=; h=Message-ID:Subject:From:To:Cc:Date:In-Reply-To:References: Content-Type:MIME-Version; b=l0Wih2GNWsD+wCyDgCUL3q+ovjqFl8a2RY0bJclK7Mz4fDO/8xJGFMhkVlcknmqcvNWYW8A4yB2sk7JahUAfInQtmL/bopcARGsp8cL5SSRMc7uPMptaF5RwPcN0E5fJR+MjQsxLpEbKH5uhxVFlC2yNSIYjfmtvL640cpIFQPE= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=A6F6DWNj; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="A6F6DWNj" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 96D6FC4CECF; Wed, 13 Nov 2024 13:45:07 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1731505508; bh=463bUkz/5tCXUXgaLe+/YHfvDlUVaS5zOq/K3ekFYDA=; h=Subject:From:To:Cc:Date:In-Reply-To:References:From; b=A6F6DWNjak7ni1g6XWHCPRUdBp8P3LzoXFdZXEqjh3WgHAh3Rr6p3NZ0HQS51Vsh7 MrDIyZ3m1coJBGpm2+9Bb2nOz9m/Rh3zScMs5J2yEortqEBbSIVL047wsRKEvS5loo tuAjYfo+8P6o3+x/gg5npOChHzElrifnqfhvxGpQA7kqLjQCgIE6oRhZ9qSZu/DP+f wjMRyoTKbBewFv/14P4IhrNE5pWIf3XHeuU/2H7e44sA8zl60KipizgPmsUinwrj0M GnJGdQii2evR8WAclBTnMFUGeGUe6AX4Ka8xY2dQW1X/zaTCF1rAk+sF/7rWxE7jSw l0HlpsTkb0ppw== Message-ID: <63f3aa4b3d69b33f1193f4740f655ce6dae06870.camel@kernel.org> Subject: Re: [PATCH v4 0/3] fs: allow statmount to fetch the fs_subtype and sb_source From: Jeff Layton To: Karel Zak , Christian Brauner Cc: Miklos Szeredi , Ian Kent , Josef Bacik , linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, Alexander Viro , Jan Kara Date: Wed, 13 Nov 2024 08:45:06 -0500 In-Reply-To: References: <20241111-statmount-v4-0-2eaf35d07a80@kernel.org> <20241112-antiseptisch-kinowelt-6634948a413e@brauner> Autocrypt: addr=jlayton@kernel.org; prefer-encrypt=mutual; keydata=mQINBE6V0TwBEADXhJg7s8wFDwBMEvn0qyhAnzFLTOCHooMZyx7XO7dAiIhDSi7G1NPxw n8jdFUQMCR/GlpozMFlSFiZXiObE7sef9rTtM68ukUyZM4pJ9l0KjQNgDJ6Fr342Htkjxu/kFV1Wv egyjnSsFt7EGoDjdKqr1TS9syJYFjagYtvWk/UfHlW09X+jOh4vYtfX7iYSx/NfqV3W1D7EDi0PqV 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Wed, 2024-11-13 at 12:27 +0100, Karel Zak wrote: > On Tue, Nov 12, 2024 at 02:39:21PM GMT, Christian Brauner wrote: > > On Mon, 11 Nov 2024 10:09:54 -0500, Jeff Layton wrote: > > > Meta has some internal logging that scrapes /proc/self/mountinfo toda= y. > > > I'd like to convert it to use listmount()/statmount(), so we can do a > > > better job of monitoring with containers. We're missing some fields > > > though. This patchset adds them. > > >=20 > > >=20 > >=20 > > Applied to the vfs.misc branch of the vfs/vfs.git tree. > > Patches in the vfs.misc branch should appear in linux-next soon. >=20 > Jeff, thank you for this! >=20 > I have already implemented support for statmount() and listmount() in > libmount (PR: https://github.com/util-linux/util-linux/pull/3092). The > only remaining issue was the mount source and incomplete file system > type. >=20 Unfortunately, I think we might be missing something else: The mountinfo (and "mounts") file generator calls show_sb_opts() which generates some strings from the sb->s_flags field and then calls security_sb_show_options(). statmount() will give you the s_flags field (or an equivalent), but it doesn't give you the security options string. So, those aren't currently visible from statmount(). How should we expose those? Should we create a new statmount string field and populate it, or is it better to just tack them onto the end of the statmount.mnt_opts string? > Currently, the library does not use these syscalls when mounting (it > still uses /proc/#/mountinfo). However, there is already a library API > to fetch mount information from the kernel using listmount+statmount, > and it can be accessed from the command line using: >=20 > findmnt --kernel=3Dlistmount >=20 Very cool. I need to play with findmnt more. > Next on the wish list is a notification (a file descriptor that can be > used in epoll) that returns a 64-bit ID when there is a change in the > mount node. This will enable us to enhance systemd so that it does not > have to read the entire mount table after every change. >=20 New fanotify events for mount table changes, perhaps? --=20 Jeff Layton