currently i have a setup with two hardrives, one with xfs, the other one with btrfs on it.The root fs is mounted on  the xfs, and the btrfs under /data.For verious reasons, the directory /var/www on the xfs was replaced by a bind mount to /data/var/www. (mount -o bind /data/var/www /var/www) So if you look in both directories (/var/www & /data/var/www) its exactly the same content.To my surprise some btrfs tools cannot handle bind mounted pathes, so whatever i i do i need for certain situations that the given path /var/ww is canonicalized to  /data/var/wwwHow can i do that with a shell tool? something like resolve /var/www  which would then return /data/var/www (or if there is more than one bind mount, it would return the proper path.
resolve bind mounts with a shell tool/script
mount;btrfs;bind