On Wed, Feb 07, 2024 at 12:40:09PM -0500, Theodore Ts'o wrote: > 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. You've still got the ext4 version, we're not taking that away. But I don't think other filesystems will want to deal with the hassle of changing UUIDs at runtime, since that's effectively used for API access via sysfs and debugfs.
