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 15DA94E1B5 for ; Mon, 12 Feb 2024 22:47:58 +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=1707778083; cv=none; b=GZo2a8VP1qwZWiLH3cJdBmUC990LX298Mua0QZSRHwMfT04C8QjXrMU412LszU2ro6pk9cQMhSYIa8CiGoAkDb+DaIsSBze23t5vOoHgQotIgZbTA5i9QctDhYTdt4TQBIA9b5efXKaSwIeImc7y7OlxW62xy4IAL9FbnRs0Q8E= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1707778083; c=relaxed/simple; bh=K1b3q4DCJkfzZWaD2YE4J3eFtLm65BGnvmVOUumr38c=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=lzMHt5a1ZkFajdGs2rqHTZ+m0kym6dtczaxp4QQZJO1cDRw0KjDys6aoP5Fy9xyoH6GrFzwvvFmo1Tz+xLAH1CgQqlJ8zQOUon+x1qHF5qrA+CY0Wl1MHjSZtBLnSo+TXGTgekPJP1LlA2PRYOX4Lq096QXoKrlC23Aa/E8g39Y= 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=TTCtApiY; 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="TTCtApiY" Received: from cwcc.thunk.org (pool-173-48-116-68.bstnma.fios.verizon.net [173.48.116.68]) (authenticated bits=0) (User authenticated as tytso@ATHENA.MIT.EDU) by outgoing.mit.edu (8.14.7/8.12.4) with ESMTP id 41CMlewn030373 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Mon, 12 Feb 2024 17:47:41 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=mit.edu; s=outgoing; t=1707778062; bh=hLuV941+qZxZ2jHcWo5oaqvsH1WX/8coaLVLS570gwU=; h=Date:From:Subject:Message-ID:MIME-Version:Content-Type; b=TTCtApiYSJKKyhHvtZwLDzSiwb4V8OAqrccxz7UT6GgMhUtBAIOo0wGI63TWHAbuo MOXjpScdHcQdCgsQ+Lrwdb5LsBXG9VB8RSEl4YkclWcW1HM8jL+XVYXrzQ+mMFXQIr RSwcwyp9pWs3CXVYK+Nlt3uENAFs9qdcwYxPQDneR+53T1uGW76ntbqAwLYqgtX1w/ xW1+B8qDhCTFBvMqdw3Pa6U/5s2zBddA+gsG7FEToF2h7J4wxwF21e92xVADhDmMYT ioAdUwAt66PyaFAMX5yO/NbIDTNK4ubR80nXp1frNFA9ARnYnlcOqrLeOb17xEiPMe 8gVtVA2ih5Swg== Received: by cwcc.thunk.org (Postfix, from userid 15806) id C4A5C15C0336; Mon, 12 Feb 2024 17:47:40 -0500 (EST) Date: Mon, 12 Feb 2024 17:47:40 -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: <20240212224740.GA394352@mit.edu> References: <20240206201858.952303-1-kent.overstreet@linux.dev> <20240207174009.GF119530@mit.edu> 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: On Wed, Feb 07, 2024 at 03:26:55PM -0500, Kent Overstreet wrote: > You've still got the ext4 version, we're not taking that away. But I > don't think other filesystems will want to deal with the hassle of > changing UUIDs at runtime, since that's effectively used for API access > via sysfs and debugfs. Thanks. I misunderstood the log. I didn't realize this was just about not hoisting the ioctl to the VFS level, and dropping the generic uuid set. I'm not convinced that we should be using the UUID for kernel API access, if for no other reason that not all file systems have UUID's. Sure, modern file systems have UUID's, and individual file systems might have to have specific features that don't play well with UUID's changing while the file system is mounted. But I'm hoping that we don't add any new interfaces that rely on using the UUID for API access at the VFS layer. After all, ext2 (not just ext3 and ext4) has supported changing the UUID while the file system has been mounted for *decades*. - Ted