Re: [PATCH 1/3] xfs: mark dir corrupt when lookup-by-hash fails

["Darrick J. Wong" <darrick.wong@oracle.com>]

On Wed, Mar 04, 2020 at 09:26:10AM +1100, Dave Chinner wrote:
> On Fri, Feb 28, 2020 at 05:49:09PM -0800, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > In xchk_dir_actor, we attempt to validate the directory hash structures
> > by performing a directory entry lookup by (hashed) name.  If the lookup
> > returns ENOENT, that means that the hash information is corrupt.  The
> > _process_error functions don't catch this, so we have to add that
> > explicitly.
> > 
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> >  fs/xfs/scrub/dir.c |    5 +++++
> >  1 file changed, 5 insertions(+)
> > 
> > 
> > diff --git a/fs/xfs/scrub/dir.c b/fs/xfs/scrub/dir.c
> > index 266da4e4bde6..54afa75c95d1 100644
> > --- a/fs/xfs/scrub/dir.c
> > +++ b/fs/xfs/scrub/dir.c
> > @@ -155,6 +155,11 @@ xchk_dir_actor(
> >  	xname.type = XFS_DIR3_FT_UNKNOWN;
> >  
> >  	error = xfs_dir_lookup(sdc->sc->tp, ip, &xname, &lookup_ino, NULL);
> > +	if (error == -ENOENT) {
> > +		/* ENOENT means the hash lookup failed and the dir is corrupt */
> > +		xchk_fblock_set_corrupt(sdc->sc, XFS_DATA_FORK, offset);
> > +		return -EFSCORRUPTED;
> > +	}
> >  	if (!xchk_fblock_process_error(sdc->sc, XFS_DATA_FORK, offset,
> >  			&error))
> >  		goto out;
> 
> So why is this error handling open coded rather than doing something
> like this to use the generic, pre-existing corruption handling:
> 
> 	if (error == -ENOENT) {
> 		/* ENOENT means the hash lookup failed and the dir is corrupt */
> 		error = -EFSCORRUPTED;
> 	}
> 	if (!xchk_fblock_process_error(sdc->sc, XFS_DATA_FORK, offset,
> 			&error))
> 		goto out;

No particular reason, I just figured that I might as well cut to setting
OFLAG_CORRUPT and bailing out.  I'll change it.

--D

> Cheers,
> 
> Dave.
> -- 
> Dave Chinner
> david@fromorbit.co