Re: [PATCH 5/6] xfs: write the rg superblock when fixing it

On Tue, Jul 14, 2026 at 07:20:11AM +0200, Christoph Hellwig wrote:
> On Mon, Jul 13, 2026 at 02:58:57PM -0700, Darrick J. Wong wrote:
> > Hrmm.  Right now both superblock scrubbers don't do much for group 0,
> > because both buffers are pinned to the xfs_mount, so they assume that
> > there's no need to check anything.  However, the ondisk super could have
> > gotten corrupted (or blown away by fdisk), in which case an immediate
> > crash could render the filesystem unmountable.
> > 
> > So, I could (a) teach the super scrubbers to read the primary / rt
> > super; and (b) teach them both to log the superblock and bwrite it
> > immediately to shorten the window in which this could happen.
> > 
> > What do you think?
> 
> I guess the only sensible time to scrub the sb would be early during
> mount? 

mount already does that, and rejects the filesystem.

The fresh reread here would only save your filesystem if you happened to
do something dumb while mounted like "ls > /dev/sdb1" and overwrote the
ondisk supers without whacking too much of the existing filesystem.

> > Also, this patch should be calling xfs_log_sb *after* xfs_trans_getsb,
> > so I'll fix that for the repost.
> 
> Oops.

Oh good, for-next got the updated version.

--D