Re: [PATCH AUTOSEL 6.18-6.12] btrfs: derive f_fsid from on-disk fsid and dev_t

[Dave Hansen]

On 8/31/26 06:23, Sasha Levin wrote:
> To prevent f_fsid collisions between original and cloned filesystems,
> this implementation hashes the dev_t for single-device btrfs filesystems
> to ensure uniqueness. This is limited to single-device filesystems as
> cloned mounts are currently only supported for that configuration. Note
> that f_fsid will change if the device is replaced.
> 
> Additionally, since the kernel cannot distinguish between the original
> and the cloned filesystem, this new f_fsid derivation is applied to
> both.

This commit is causing some real pain to end users that use the FSID to
encrypt VPN keys. Could we keep it out of the stable kernels for the
moment, please?