From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from verein.lst.de (verein.lst.de [213.95.11.211]) (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 1EA773570C1; Fri, 16 Jan 2026 09:36:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=213.95.11.211 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768556211; cv=none; b=fLghZB+8ajwRH9bFy1w6vEIOPhCoVUCnIdhYbbPeUmRVGy6SXvXNJl3sYvKR3pJ/vS16h/3m7WdDmNtafTD3LyeM4FmOwwcN9wlCMln9hyLjPEQP2u9hNoI6SLij+1tVscdjByelVBKAj0HRMllL/Eig/SW0QpMx+z7pNBCHshs= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768556211; c=relaxed/simple; bh=JDWJrbRjIFrw3KLEL0PaTeoWEdHsfnETA4l/qAIRuc8=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=pasODqnfzhM8NUfrUYPUHgvaIq7BDv2DzklXviyuaSUjqG3H9OLcs4rFDu7ZbaOUyqGnxzdddD+IOye0XLhOgqwwRwirmOKHIqjNFPqS1Ne+66jZtc4TLtOd8Tvsw/RkvftQk53GW43jXefxIXhtbBwAPs1t5WmwZGErc4dqRDI= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de; spf=pass smtp.mailfrom=lst.de; arc=none smtp.client-ip=213.95.11.211 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=lst.de Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=lst.de Received: by verein.lst.de (Postfix, from userid 2407) id 0E16B227A8E; Fri, 16 Jan 2026 10:36:44 +0100 (CET) Date: Fri, 16 Jan 2026 10:36:43 +0100 From: Christoph Hellwig To: =?iso-8859-1?Q?Andr=E9?= Almeida Cc: Amir Goldstein , Christoph Hellwig , Chuck Lever , Jeff Layton , NeilBrown , Olga Kornievskaia , Dai Ngo , Tom Talpey , Carlos Maiolino , Chris Mason , David Sterba , Miklos Szeredi , Christian Brauner , Alexander Viro , Jan Kara , linux-nfs@vger.kernel.org, linux-kernel@vger.kernel.org, linux-xfs@vger.kernel.org, linux-fsdevel@vger.kernel.org, Qu Wenruo , linux-btrfs@vger.kernel.org, linux-unionfs@vger.kernel.org, kernel-dev@igalia.com Subject: Re: [PATCH 3/3] ovl: Use real disk UUID for origin file handles Message-ID: <20260116093643.GA23235@lst.de> References: <20260114-tonyk-get_disk_uuid-v1-0-e6a319e25d57@igalia.com> <20260114-tonyk-get_disk_uuid-v1-3-e6a319e25d57@igalia.com> <20260114062608.GB10805@lst.de> <5334ebc6-ceee-4262-b477-6b161c5ca704@igalia.com> <20260115062944.GA9590@lst.de> <633bb5f3-4582-416c-b8b9-fd1f3b3452ab@suse.com> <20260115072311.GA10352@lst.de> <22b16e24-d10e-43f6-bc2b-eeaa94310e3a@igalia.com> <0241e2c4-bf11-4372-9eda-cccaba4a6d7d@igalia.com> 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=iso-8859-1 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <0241e2c4-bf11-4372-9eda-cccaba4a6d7d@igalia.com> User-Agent: Mutt/1.5.17 (2007-11-01) On Thu, Jan 15, 2026 at 03:55:15PM -0300, André Almeida wrote: >> Is there any guarantee that file handles are relevant and point to the >> same objects? >> >> The whole point of the overlayfs index feature is that overlayfs inodes >> can have a unique id across copy-up. >> >> Please explain in more details exactly which overlayfs setup you are >> trying to do with index feature. >> > > The problem happens _before_ switching from A to B, it happens when trying > to install the same image from A on B. > > During the image installation process, while running in A, the B image will > be mounted more than once for some setup steps, and overlayfs is used for > this. Because A have the same UUID, each time B is remouted will get a new > UUID and then the installation scripts fails mounting the image. It sounds like the 'clones' really need different persistent uuids. Or do you also have a requirement that the two images have the same ID, which would require a noouid-like option and extremely careful handling.