Re: [PATCH v2 0/7] filesystem visibililty ioctls

[Theodore Ts'o]

On Tue, Feb 06, 2024 at 03:18:48PM -0500, Kent Overstreet wrote:
> previous:
> https://lore.kernel.org/linux-fsdevel/20240206-aufwuchs-atomkraftgegner-dc53ce1e435f@brauner/T/
> 
> Changes since v1:
>  - super_set_uuid() helper, per Dave
> 
>  - nix FS_IOC_SETUUID - Al raised this and I'm in 100% agreement,
>    changing a UUID on an existing filesystem is a rare operation that
>    should only be done when the filesystem is offline; we'd need to
>    audit/fix a bunch of stuff if we wanted to support this

NAK.  First, this happens every single time a VM in the cloud starts
up, so it happens ZILLIONS of time a day.  Secondly, there is already
userspace programs --- to wit, tune2fs --- that uses this ioctl, so
nixing FS_IOC_SETUUID will break userspace programs.

							- Ted