From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-pf1-f170.google.com (mail-pf1-f170.google.com [209.85.210.170]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id A11AD188596 for ; Tue, 14 Oct 2025 23:46:41 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.210.170 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760485603; cv=none; b=C5ZxBQSKTzuOVsBkLO+uV+KCRoo1bB4i5s+pdhVf2cvTQBPuh5HbBN9SzpeVqgCCQz9KdjQ5ZpHj2y4WeqRlaIVy8UkNG0Q4aNUtqC/xVC5ZEvoiPunqAK8009QFYFeVdDnfnbSNEMrPEWy0E6mdKq9YD+1NWUQdtroJBxLu7Jk= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1760485603; c=relaxed/simple; bh=LYVfye+2jfXWF34eSuJa02pO1di01Vh1l2AkQHnLeTk=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=FYExNpbbKQ8FMmJg46eYh1LOPjvxr13h9RGZ2pB04X+0R9Md/I6xtkogv1P/l53dSTRzqddF5dCmqeoLJ7N9zHRE11NQ8qcxLBOgc2Vz4ZgqsgsdK13x7ZpOf2Ce7XHH7whlqlsWQbBcpZbJStYmLTAdvX6t4RX3yPUkVYTDLug= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com; spf=pass smtp.mailfrom=gmail.com; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b=M+sdaSm6; arc=none smtp.client-ip=209.85.210.170 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=gmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=gmail.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="M+sdaSm6" Received: by mail-pf1-f170.google.com with SMTP id d2e1a72fcca58-79af647cef2so2682236b3a.3 for ; Tue, 14 Oct 2025 16:46:41 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20230601; t=1760485601; x=1761090401; darn=vger.kernel.org; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :from:to:cc:subject:date:message-id:reply-to; bh=vakVPAnhG+s33WW+yk2avQxhwmCtmmfNm1U+3y8SU9U=; b=M+sdaSm6ikHxiCKxEBWa65a6P8lemsSNKSOMi3m+0ZRisQaZJiyqX/fUsgE0fJGv5D wiMJRAwf2vPV8RMQH4oqsDGzlgIlpDrVdDwU7FkdBAJmwcCluNGuSbE7/axF2PYXI8AO 2mbkqC8p1vd1bG93X4/p4yr9vf/Ohiks7HtjgODatTjWKt4VQffDTCTqQiILRJ+Hb//3 q+sl3HYekmYEqIC1yPjcDvP/kc0+RydoUjD6NTMDGYHtgzNKnqXZVX96MCOJ+87O0xxf hf/CNyQHZIRYGMzpj3iVxsWMdOBr2fhP55RHxhSWVN8rQ6IekB56Jai55Ei47DoDA0cw jP9Q== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20230601; t=1760485601; x=1761090401; h=content-transfer-encoding:in-reply-to:from:references:cc:to :content-language:subject:user-agent:mime-version:date:message-id :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=vakVPAnhG+s33WW+yk2avQxhwmCtmmfNm1U+3y8SU9U=; b=JXzOi2XfrOFNxczf7x2A9Qn57sU79pSKmdxHCGMn6rbyLmJ5Vg/Av0daJnFKA0wbnW ESZMdoQ3xLpunwknmu21bDXVRYdnq29m+OT3gKk/rm1NogyGfQ7nKuncQ+DGrrThb+N4 ssGZSUAQsPYfOoR+0Y8n3ZvzWpC7O6kzrHfb5n8acc5k3rSJ/adUKZBG7xDmvMf0eg+D omf2rA/cJMA9Bp5O8YKivEdLXRJjZBOigFZ12CiLBrc7kmKE8TXh9x7nwuhIe9QP6235 zuoIDqjaSP+gSDdtlQgpFvcJRUp/hSzLHkNQbDL0fH6b+gvT3VibW+OhDiJyRO1Vu47t Vs6Q== X-Gm-Message-State: AOJu0Yw2AlYI/uvMThN9NcwD35exjBHvlvB9sNpcnFa9IFPd6WqvkV85 +ABaq+iJgYI7OPYa2ScR/V2rja8ZZrVGcIqPdI8LLir0B+eKspFEl+R/ X-Gm-Gg: ASbGnctCTUU3e517gQw5EeiHWE86hh2sCsIHpv7HY1yesEr8L6o5B+uGEupshyWjS5y GYya0yLxdSqRI/lqJqhgJCbEuIIpz58kaW6Oir0DR0mwkQYPEpp5cgwwWvhKt0CX3+YyYL6Zxp9 O02xSG/P/mWgNJTuI65U5A70HT6QuZkvgr708fsUHESSLeUwPdwrSRg42BdvUlJexkdC465d3ek 6YFK+yNaxXmH7hTdiAFQ+mNeijb2fzK158r+7W+6ng9qArJM2M5gBWO1lBb8zlp0TQ7eSpVykiQ fHCK1tKTdkIMryOMoEyIPQVTQfyLk5eNwP7GxaRc/LeCdmUxJtnknVN4r/X+b22zcyEWJNrgPlw cB0r64i6OQDOjqVt9DQvqx/5IaJmP/rcfYwpezC7doTzNEkoSpjOSL3ZYQG06lO1xwobOEDieHS 5eudbIevL4g7cDbW0XIP9BeA== X-Google-Smtp-Source: AGHT+IECtas5D0AKF7k+YfLgDtLgwNAopAU187v8QEFHEo1/tzXFB8c6NJkc8BI7xOANIs0x94HcQg== X-Received: by 2002:a17:90b:1d85:b0:335:28ee:eebe with SMTP id 98e67ed59e1d1-33b5138e625mr35422665a91.30.1760485600940; Tue, 14 Oct 2025 16:46:40 -0700 (PDT) Received: from [10.130.1.37] ([118.200.221.61]) by smtp.gmail.com with ESMTPSA id 41be03b00d2f7-b678df2799esm12802604a12.29.2025.10.14.16.46.38 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Tue, 14 Oct 2025 16:46:40 -0700 (PDT) Message-ID: <5137ce36-c3b4-4a0a-83af-e00892feaf43@gmail.com> Date: Wed, 15 Oct 2025 07:46:34 +0800 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [RFC PATCH 1/1] ovl: Use fsid as unique identifier for trusted origin Content-Language: en-GB To: Christoph Hellwig , =?UTF-8?Q?Andr=C3=A9_Almeida?= Cc: linux-kernel@vger.kernel.org, linux-btrfs@vger.kernel.org, linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, kernel-dev@igalia.com, Miklos Szeredi , Amir Goldstein , Chris Mason , David Sterba , "Guilherme G . Piccoli" References: <20251014015707.129013-1-andrealmeid@igalia.com> <20251014015707.129013-2-andrealmeid@igalia.com> From: Anand Jain In-Reply-To: Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit On 14-Oct-25 12:39 PM, Christoph Hellwig wrote: > On Mon, Oct 13, 2025 at 10:57:07PM -0300, André Almeida wrote: >> Some filesystem have non-persistent UUIDs, that can change between >> mounting, even if the filesystem is not modified. To prevent >> false-positives when mounting overlayfs with index enabled, use the fsid >> reported from statfs that is persistent across mounts. > > Please fix btrfs to not change uuids, as that completely defeats the > point of uuids. We needed cloned device mount support for an A/B testing use case, but changing the on-disk UUID defeats the purpose. Right now, ext4 and Btrfs can mount identical devices, but XFS can't. How about extending this to the common VFS layer and adding a parameter to tell apart a cloned device from the same device accessed through multiple paths? I haven't looked into the details yet, but I can dig it further.