From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from outgoing.mit.edu (outgoing-auth-1.mit.edu [18.9.28.11]) (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 304CF82877 for ; Wed, 7 Feb 2024 17:40:37 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=18.9.28.11 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707327640; cv=none; b=cRO2DOVvWZIBSYDXl5rIgNGzLbEu/7uYfNU5EdkSxVNxbVAq6IK5+jzKyrV/DkkmNUfqsPC/Lw6szso0m0wsFnoDgWXsR1GRhjC+BkJMq2Np8w/Xh697RdauSQazWWqKVhA+xM/Pv9LeMkTHRO/694HUAbQRaIMYwHjKorRVvC4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707327640; c=relaxed/simple; bh=rpxr7u3oQ1f9tEqbE9lXrYaJvrFwR/A74/ikjVgV3ZM=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=IWATgqOPHtMZS0WgCMLI6SA2xkHrg8KV021bE6rBA1q4yXNF2iBIi8BDa9ak1KBvmnaKIr6Ro0/JdnoFSoW+ZsDG7uPdmRrjTeO+35x10D15eMe0gFKy8MbhzdkWU2vk42nB/fSvgOQjtRTdxGDGaNQjNSnz80DvrhqwfIKu1F0= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=mit.edu; spf=pass smtp.mailfrom=mit.edu; dkim=pass (2048-bit key) header.d=mit.edu header.i=@mit.edu header.b=ElgKNZ5o; arc=none smtp.client-ip=18.9.28.11 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=mit.edu Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=mit.edu Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=mit.edu header.i=@mit.edu header.b="ElgKNZ5o" Received: from cwcc.thunk.org (pool-173-48-82-236.bstnma.fios.verizon.net [173.48.82.236]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 417HeA6o025052 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Wed, 7 Feb 2024 12:40:11 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mit.edu; s=outgoing; t=1707327611; bh=r9d+Doi+WOPExniXtR89NcGFZiyjO8sS0Kv850JhT+s=; h=Date:From:Subject:Message-ID:MIME-Version:Content-Type; b=ElgKNZ5oonmgRLpIzI3lEjYU0M4Q1AG+KxP3Hn5nZrqGeeOyYIQI//NCsu4L21v9R i/CWDGDO5QJVbhWmAExjfUSsBfRYu71xyN6qi1miw0pzrzhkot8MVXaaxpK5cvTaMT uUwJpI2inNyLu3pyywvD8/q3vc21Ngn6Zvv2XGnA3KKFlaM3WBQt/3+Eah95gvpxcS qaGB/DG0mgkdEmYoL0AZp0X7Mh91UK8ZNfj2DTY/wYFmbJf9bUIjRKe1B3fJOuCdhP BrsNXho4czpGFJL6BTsOOp6m8uxNgSiY+0fbT9ddo3IYeV9Y2N6jZPebI8LM/JKURg qBZxnLbQDEYYQ== Received: by cwcc.thunk.org (Postfix, from userid 15806) id C74A215C02FD; Wed, 7 Feb 2024 12:40:09 -0500 (EST) Date: Wed, 7 Feb 2024 12:40:09 -0500 From: "Theodore Ts'o" To: Kent Overstreet Cc: brauner@kernel.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v2 0/7] filesystem visibililty ioctls Message-ID: <20240207174009.GF119530@mit.edu> References: <20240206201858.952303-1-kent.overstreet@linux.dev> Precedence: bulk X-Mailing-List: linux-fsdevel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20240206201858.952303-1-kent.overstreet@linux.dev> On Tue, Feb 06, 2024 at 03:18:48PM -0500, Kent Overstreet wrote: > previous: > https://lore.kernel.org/linux-fsdevel/20240206-aufwuchs-atomkraftgegner-dc53ce1e435f@brauner/T/ > > Changes since v1: > - super_set_uuid() helper, per Dave > > - nix FS_IOC_SETUUID - Al raised this and I'm in 100% agreement, > changing a UUID on an existing filesystem is a rare operation that > should only be done when the filesystem is offline; we'd need to > audit/fix a bunch of stuff if we wanted to support this NAK. First, this happens every single time a VM in the cloud starts up, so it happens ZILLIONS of time a day. Secondly, there is already userspace programs --- to wit, tune2fs --- that uses this ioctl, so nixing FS_IOC_SETUUID will break userspace programs. - Ted