Re: File system corruption due to UFS2 extended attributes

[Crystal Kolipe <kolipe.c%exoticsilicon.com@localhost>]

On Wed, May 25, 2022 at 02:00:44AM -0700, Chuck Silvers wrote:
> On Tue, May 24, 2022 at 07:51:08AM -0400, Greg Troxel wrote:
> > And same questions for the other active BSD variants, which I think is
> > mostly OpenBSD and Dragonfly these days but I have lost track.
> 
> OpenBSD UFS2 appears to be the same as NetBSD <=9 with respect to
> extended attributes (extattrs are not supported).  OpenBSD's treatment
> of fs_flags is different as well, only two fs_flags bits are recognized
> and unknown flags are not cleared.  At least one superblock field
> is different too.

With regards to exchanging filesystems between OpenBSD and NetBSD, it's
worth noting that OpenBSD has also diverged slightly in the format of the
disklabel, for example by repurposing some old and little used fields to
hold a DUID value.

This _may_ imply that it's safe(r) to assume that anybody sharing a UFS2
filesystem between OpenBSD and another BSD system knows what they are
doing, as they will likely already have encountered compatibility issues
if they have got far enough for the UFS2 extended attributes to be a
concern.

FreeBSD and DragonflyBSD are basically the same as NetBSD in terms of
disklabel layout, so that issue doesn't exists.

For more information, see the sections:

'BSD disklabels - compatibility betweeen BSDs'
'BSD disklabels - enhancements in OpenBSD'

of:

https://www.exoticsilicon.com/jay/reckless_guide_to_openbsd/bsd_disklabels

or

gemini://gemini.exoticsilicon.com/jay/reckless_guide_to_openbsd/bsd_disklabels