Mount Ext3 under DragonFlyBSD

[v_2e@xxxxxxx]

  Hello!
  I'm new (well, actually, very very very new) to DragonFlyBSD and
currently doing my first steps with it.  I have Ext2 and Ext3
partitions on my HDD (created under GNU/Linux) and I cannot use them
under DragonFlyBSD. The problem is that when I try to mount any of
them, I get the following error message:

    # mount /dev/ad4s3 /mnt/data/
    mount: /dev/ad4s3 on /mnt/data: incorrect super block

Or if I state the FS type explicitly, I get this:

    # mount -t ext2fs /dev/ad4s3 /mnt/data/
    WARNING: R/W mount of #ad/0x40002 denied due to unsupported
optional features 
    ext2fs: /dev/ad4s3: Invalid argument

  The only mode I can mount these file systems in is read-only mode.
However, the file systems are not usable in this mode either, because I
can only list the root catalog of the corresponding FS. Any attempt to
list other catalogs or read some files leads to the following
error message on the screen:

and a system reboot.

I searched over Internet for a similar issue and found only one sane
article mentioning this problem
( http://onlamp.com/pub/a/bsd/2000/11/16/Big_Scary_Daemons.html ). Its
author tells that the root of the problem is the 'sparse_super' flag
set on the Ext2 file system and suggest to turn this flag off:

    tune2fs -s off /dev/sda3

I tried it under my GNU/Linux system, but it says only:

    Clearing filesystem feature 'sparse_super' not supported.

and does not do the job.
  So now I just do not know what to do. How cat I use my existing
Ext2/Ext3 file systems on DragonFlyBSD? Any suggestions?

  Thanks.
    Vladimir

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