Yes Hardlinking files would be a dangerous idea, in my opinion What is good with the FIDEDUPERANGE ioctl is that everything is transparent from the user space

Yes Hardlinking files would be a dangerous idea, in my opinion What is good with the FIDEDUPERANGE ioctl is that everything is transparent from the user space point of view: whatever are the files, whatever they are used for, nothing have changed When you hardlink, you see that, at the current moment, files are the same, but then you assume that userspace wants those files to stay the same To me, this sounds like a recipe for a disaster This ioctl lives at the vfs layer. As of now, btrfs and xfs has implemented it. There is a merge request lurking around for zfs, and I have yet to check what is bcachefs' status on this The only top player left is ext4 :/ (disclosure: I work on duperemove)