[LSF/MM TOPIC] VFS rename fences/zones/whatuwanacallit

[Al Viro]

On Fri, Feb 22, 2019 at 09:08:24AM +0200, Amir Goldstein wrote:
> Last minute proposal for fs track.
> This is something that's been on my mind for a while
> and I was wondering if others have interest in something like this.
> 
> The idea is to declare a directory as a root of a subtree from
> which inodes cannot escape via rename/link.

'scalled "mount"...  That's precisely the reason why cross-device
operations prevention is "different mounts", not just "different
superblocks".  Why bother doing that on dentry level?