linux-kernel - Re: [PATCH 3/3] ovl: Use real disk UUID for origin file handles

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <20260115160816.GA16080@lst.de>
Date: Thu, 15 Jan 2026 17:08:16 +0100
From: Christoph Hellwig <hch@....de>
To: André Almeida <andrealmeid@...lia.com>
Cc: Christoph Hellwig <hch@....de>, Chuck Lever <chuck.lever@...cle.com>,
	Jeff Layton <jlayton@...nel.org>, NeilBrown <neil@...wn.name>,
	Olga Kornievskaia <okorniev@...hat.com>,
	Dai Ngo <Dai.Ngo@...cle.com>, Tom Talpey <tom@...pey.com>,
	Carlos Maiolino <cem@...nel.org>,
	Amir Goldstein <amir73il@...il.com>, Chris Mason <clm@...com>,
	David Sterba <dsterba@...e.com>, Miklos Szeredi <miklos@...redi.hu>,
	Christian Brauner <brauner@...nel.org>,
	Alexander Viro <viro@...iv.linux.org.uk>, Jan Kara <jack@...e.cz>,
	linux-nfs@...r.kernel.org, linux-kernel@...r.kernel.org,
	linux-xfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	Qu Wenruo <wqu@...e.com>, linux-btrfs@...r.kernel.org,
	linux-unionfs@...r.kernel.org, kernel-dev@...lia.com
Subject: Re: [PATCH 3/3] ovl: Use real disk UUID for origin file handles

On Thu, Jan 15, 2026 at 12:42:33PM -0300, André Almeida wrote:
>> So André, can you confirm this what you're worried about?  And btrfs
>> developers, I think the main problem is indeed that btrfs simply allows
>> mounting the same fsid twice.  Which is really fatal for anything using
>> the fsid/uuid, such NFS exports, mount by fs uuid or any sb->s_uuid user.
>>
>
> Yes, I'm would like to be able to mount two cloned btrfs images and to use 
> overlayfs with them. This is useful for SteamOS A/B partition scheme.

Then you'll really need to assign them different (persistent) fsids/uuids.