linux-kernel - Re: [RFC PATCH 1/1] ovl: Use fsid as unique identifier for trusted origin

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Message-ID: <aO3T8BGM6djYFyrz@infradead.org>
Date: Mon, 13 Oct 2025 21:39:12 -0700
From: Christoph Hellwig <hch@...radead.org>
To: André Almeida <andrealmeid@...lia.com>
Cc: linux-kernel@...r.kernel.org, linux-btrfs@...r.kernel.org,
	linux-unionfs@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	kernel-dev@...lia.com, Miklos Szeredi <miklos@...redi.hu>,
	Amir Goldstein <amir73il@...il.com>, Chris Mason <clm@...com>,
	David Sterba <dsterba@...e.com>, Anand Jain <anand.jain@...cle.com>,
	"Guilherme G . Piccoli" <gpiccoli@...lia.com>
Subject: Re: [RFC PATCH 1/1] ovl: Use fsid as unique identifier for trusted
 origin

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.