Re: File system corruption due to UFS2 extended attributes

[Chuck Silvers <chuq%chuq.com@localhost>]

On Tue, May 24, 2022 at 06:25:34AM -0000, Michael van Elst wrote:
> chuq%chuq.com@localhost (Chuck Silvers) writes:
> 
> > - fsck will take a new option "-c ea" to specify that an existing UFS2
> >   file system should be converted to support extended attributes
> >   (ie. converted to UFS2ea).  This conversion first clears all of the on-disk
> >   pointers to extended attribute blocks (the inode "di_extb" field),
> >   since in NetBSD releases prior to NetBSD 10, those pointers could only
> >   have been set to non-zero values by corruption in the file system.
> 
> There should be a way back so that the filesystem becomes usuable
> by netbsd-9 again (basically: clear di_extb and set magic to UFS2).
> Would also be nice to pull up that feature to netbsd-9.

(please don't remove current-users from the cc, this discussion is
as much for that audience as it is for tech-kern)

having an option to fsck to convert back to non-ea UFS2 is reasonable,
with the warning that this results in throwing away all extattrs in the fs.
I'll add that.  note that this will also free any blocks which were
being used to store extattr data.

back-porting that option to netbsd-9 can be done as well,
though of course it wouldn't help if the fs in question is the root fs.

-Chuck