On Tue, May 2, 2017 at 5:17 PM, Christoph Hellwig <hch@xxxxxx> wrote: > On Tue, May 02, 2017 at 05:13:56PM +0300, Amir Goldstein wrote: >> How can it create problems if uniqueness is not guaranteed with >> Current s_uuid? Even if we did make the xfs uuid table code generic >> It couldn't be the vfs default. Filesystems will have to opt in. > > It creates problems if you e.g. mount an ext4 fs and a dm snaphot of > it. The non-XFS file systems are simply buggy in this regard. > > Non-uniqueue uuids are an absolute no-go. I'm not sure I follow your specific concern here. Surely you are not proposing to get rid of the nouuid mount option, are you? So what's the point of hiding the fact that there are 2 mounted filesystems with the same uuid from VFS? Because that is the the only implication of exporting s_uuid regardless of nouuid mount option. Whether or not ext4 and other fs should restrict multi mount of same uuid is a completely different issue. Amir.
