df vs. stat: fstype different

[Bernhard Voelker]

How can the file system type be different in df and stat?

Test case: a share of the VirtualBox host mounted in the client.
VBox host: Windows 7, i.e. the physical file system is NTFS.
VBox VM: OpenSuSE-12.2.
The host's share is mounted with file system type "vboxsf"
which shown like that by df:

  $ src/df -hT  ~/share/.
  Filesystem     Type    Size  Used Avail Use% Mounted on
  none           vboxsf  183G  170G   14G  93% /home/berny/share

However, this is what stat reports:

  $ src/stat -c "%t %T" -f ~/share/.
  6969 nfs

The statfs call is used by both commands and returns NFS:

  statfs("/home/berny/share", {f_type="NFS_SUPER_MAGIC", ...}) = 0

But how can that happen? I know, /proc/self/mounts contains
"vboxsf" which is used by df, but why does statfs return "nfs"?

Have a nice day,
Berny