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X-CSE-ConnectionGUID: SYzTBj2yS9+kIjeugSaSXg== X-CSE-MsgGUID: bF251KzDSPykIDp7ZXdklg== X-IronPort-AV: E=McAfee;i="6800,10657,11901"; a="100773" X-IronPort-AV: E=Sophos;i="6.27,97,1787036400"; d="scan'208";a="100773" Received: from fmviesa005.fm.intel.com ([10.60.135.145]) by fmvoesa116.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Sep 2026 05:32:26 -0700 X-CSE-ConnectionGUID: gzih77S/RT+YXTMRiWZMxw== X-CSE-MsgGUID: v+7is4PaTHuYqviUqzSQZw== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.27,97,1787036400"; d="scan'208";a="277160092" Received: from smithj1-mobl2.amr.corp.intel.com (HELO [10.125.108.26]) ([10.125.108.26]) by fmviesa005-auth.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 11 Sep 2026 05:32:26 -0700 Message-ID: Date: Fri, 11 Sep 2026 05:32:24 -0700 Precedence: bulk X-Mailing-List: linux-btrfs@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH 1/3] btrfs: derive f_fsid from on-disk fsuuid and dev_t To: Anand Jain , linux-btrfs@vger.kernel.org, David Sterba , David Woodhouse , "Macieira, Thiago" References: Content-Language: en-US From: Dave Hansen Autocrypt: addr=dave.hansen@intel.com; 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charset=UTF-8 Content-Transfer-Encoding: 7bit On 2/26/26 06:27, Anand Jain wrote: > Currently, f_fsid depends on fs_devices->fsid. For cloned devices, this > value is dynamic and fluctuates across mount cycles. This inconsistency > breaks persistence for subsystems like IMA. > > Switch to a stable derivation using the persistent on-disk fsuuid + > root id + devt of the block device for the single device filesystem. > This is consistent as long as the device remains unchanged/replace > (excludes btrfs device replace secnario for now). This commit evidently hit 7.2 and is causing end users some real pain. Real software uses the FSID to encrypt/decrypt their VPN key files: https://github.com/NetworkManager/NetworkManager-openconnect/ When this gets applied, those users suddenly can't connect to their VPN any more. Having a stable derivation does seem like a good idea, of course. Is there any way to make this transition without breaking existing userspace and existing users? It looks like this is also getting -stable backports.