Re: btrfs multiple mounts stacked on the same mount point

[Anand Jain <Anand.Jain@oracle.com>]

> BTW, another (general) reason over-mounts are sometimes used is to
> deliberately obscure what's underneath.  It's worth noting that anything
> with a file already open on the underlying filesystem still has access to
> that file after something else is mounted over top, and that fact is
> sometimes used to control access to certain files/filesystems, by
> starting whatever it is that needs to access them and letting them open
> the files they need, then over-mounting a different filesystem, often
> empty, so no other applications can access the under-mounted files.


  Thanks. Makes sense theoretically. Any eg of real practical 
application ? Any product in the market using it that way ?


  looks btrfs-progs shouldn't depend on the mnt-point driven ioctls
  to manage the FS. Now that's a set of challenges.


Thanks, Anand