cause of xfsdump msg: root ino 192 differs from mount dir ino 256

[L A Walsh <xfs@tlinx.org>]

When I xfsdump my /home partition, I see the above diagnostic
where it  lists "bind mount?" might be involved, but as far as
I can see, that's not the case.

grepping for '/home\s' on output of mount:

/bin/mount|grep -P '/home\s'

shows only 1 entry -- nothing mounted on top of it:

/dev/mapper/Space-Home2 on /home type xfs (...)

I have bind-mounts of things like
/home/opt  on /opt, but that shouldn't affect the root node,
as far as I know.

So what would cause the root node to differ from the mountdir
ino?

I try mounting the same filesystem someplace new:

# df .
Filesystem        Size  Used Avail Use% Mounted on
/dev/Space/Home2  2.0T  1.5T  569G  73% /home

mkdir /home2
Ishtar:home# mount /dev/Space/Home2 /home2

Ishtar:home# ll -di /home /home2
256 drwxr-xr-x 40 4096 Nov  1 10:23 /home/
256 drwxr-xr-x 40 4096 Nov  1 10:23 /home2/

Shows 256 as the root inode.  So why is xfsdump claiming
192 is root inode?

I used xfs_db and 192 is allocated to a normal file, while
256 displays nothing for the filename.

How should I further debug this?