btrfs: verify that subvolume mounts are unaffected by tempfsid

The tempfsid logic must determine whether the incoming mount request
is for a device already mounted or a new device mount. Verify that it
recognizes the device already mounted well by creating reflink across
the subvolume mount points.

Reviewed-by: Filipe Manana <fdmanana@suse.com>
Signed-off-by: Anand Jain <anand.jain@oracle.com>
2 files changed