linux-kernel - Re: [PATCH 1/3] exportfs: Rename get_uuid() to get_disk

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: <20260114062424.GA10805@lst.de>
Date: Wed, 14 Jan 2026 07:24:24 +0100
From: Christoph Hellwig <hch@....de>
To: "Darrick J. Wong" <djwong@...nel.org>
Cc: André Almeida <andrealmeid@...lia.com>,
	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,
	linux-btrfs@...r.kernel.org, linux-unionfs@...r.kernel.org,
	kernel-dev@...lia.com
Subject: Re: [PATCH 1/3] exportfs: Rename get_uuid() to get_disk_uuid()

On Tue, Jan 13, 2026 at 10:10:28PM -0800, Darrick J. Wong wrote:
> On Wed, Jan 14, 2026 at 01:31:41AM -0300, André Almeida wrote:
> > To make clear which UUID is being returned, rename get_uuid() to
> > get_disk_uuid(). Expand the function documentation to note that this
> > function can be also used for filesystem that supports cloned devices
> > that might have different UUIDs for userspace tools, while having the
> > same UUID for internal usage.
> 
> I'm not sure what a "disk uuid" is -- XFS can store two of them in the
> ondisk superblock: the admin-modifiable one that blkid reports, and the
> secret one that's stamped in all the metadata and cannot change.

It isn't.  Totally independent of the rest of the discussion, the
get_uuid exportfs operation is not useful for anything but the original
pNFS block layout.  Which is actually pretty broken and should be slowly
phased out.

> IIRC XFS only shares the user-visible UUID, but they're both from the
> disk.   Also I'm not sure what a non-disk filesystem is supposed to
> provide here?

Yeah.