From: Christoph Hellwig <hch@infradead.org>
To: Anand Jain <anajain.sg@gmail.com>
Cc: "Christoph Hellwig" <hch@infradead.org>,
"André Almeida" <andrealmeid@igalia.com>,
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" <miklos@szeredi.hu>,
"Amir Goldstein" <amir73il@gmail.com>, "Chris Mason" <clm@fb.com>,
"David Sterba" <dsterba@suse.com>,
"Guilherme G . Piccoli" <gpiccoli@igalia.com>
Subject: Re: [RFC PATCH 1/1] ovl: Use fsid as unique identifier for trusted origin
Date: Tue, 14 Oct 2025 18:22:41 -0700 [thread overview]
Message-ID: <aO73YTmDIhHkg3XB@infradead.org> (raw)
In-Reply-To: <5137ce36-c3b4-4a0a-83af-e00892feaf43@gmail.com>
On Wed, Oct 15, 2025 at 07:46:34AM +0800, Anand Jain wrote:
> 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.
If you clone a device you need to change the user visible uuid/fsid,
and you need to do that explicitly to a known either saved or user
controlled value. Assigning a random ID is highly dangerous as seen
here.
next prev parent reply other threads:[~2025-10-15 1:22 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
2025-10-14 1:57 [RFC PATCH 0/1] ovl: brtfs' temp_fsid doesn't work with ovl index=on André Almeida
2025-10-14 1:57 ` [RFC PATCH 1/1] ovl: Use fsid as unique identifier for trusted origin André Almeida
2025-10-14 4:39 ` Christoph Hellwig
2025-10-14 5:13 ` Qu Wenruo
2025-10-14 17:40 ` David Sterba
2025-10-14 17:55 ` André Almeida
2025-10-14 23:46 ` Anand Jain
2025-10-15 1:22 ` Christoph Hellwig [this message]
2025-10-20 21:43 ` Dave Chinner
2025-10-21 1:16 ` Anand Jain
2025-10-14 19:52 ` kernel test robot
2025-10-15 10:52 ` Amir Goldstein
2025-10-14 5:26 ` [RFC PATCH 0/1] ovl: brtfs' temp_fsid doesn't work with ovl index=on Qu Wenruo
2025-10-14 18:24 ` David Sterba
2025-10-14 21:08 ` Qu Wenruo
2025-10-15 0:05 ` Anand Jain
2025-10-15 4:18 ` Qu Wenruo
2025-10-14 22:04 ` Anand Jain
2025-10-15 11:09 ` Amir Goldstein
2025-10-16 4:57 ` Christoph Hellwig
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