On Mon, 02 Aug 2021, Al Viro wrote:

On Mon, Aug 02, 2021 at 02:18:29PM +1000, NeilBrown wrote:

quoted

It think we need to bite-the-bullet and decide that 64bits is not
enough, and in fact no number of bits will ever be enough.  overlayfs
makes this clear.

Sure - let's go for broke and use XML.  Oh, wait - it's 8 months too
early...

quoted

So I think we need to strongly encourage user-space to start using
name_to_handle_at() whenever there is a need to test if two things are
the same.

... and forgetting the inconvenient facts, such as that two different
fhandles may correspond to the same object.

Can they?  They certainly can if the "connectable" flag is passed.
name_to_handle_at() cannot set that flag.
nfsd can, so using name_to_handle_at() on an NFS filesystem isn't quite
perfect.  However it is the best that can be done over NFS.

Or is there some other situation where two different filehandles can be
reported for the same inode?

Do you have a better suggestion?

NeilBrown