Re: [PATCH] xfs: don't fail when converting shortform attr to long form during ATTR_REPLACE

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

On Wed, Apr 18, 2018 at 10:45:21AM +1000, Dave Chinner wrote:
> On Tue, Apr 17, 2018 at 05:31:30PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <darrick.wong@oracle.com>
> > 
> > Kanda Motohiro reported that expanding a tiny xattr into a large xattr
> > fails on XFS because we remove the tiny xattr from a shortform fork and
> > then try to re-add it after converting the fork to extents format having
> > not removed the ATTR_REPLACE flag.  This fails because the attr is no
> > longer present, causing a fs shutdown.
> > 
> > This is derived from the patch in his bug report, but we really
> > shouldn't ignore a nonzero retval from the remove call.  Something's
> > broken and we should bail out and shut down.
> > 
> > Bugzilla: https://bugzilla.kernel.org/show_bug.cgi?id=199119
> > Reported-by: kanda.motohiro@gmail.com
> > Signed-off-by: Darrick J. Wong <darrick.wong@oracle.com>
> > ---
> >  fs/xfs/libxfs/xfs_attr.c |    9 ++++++++-
> >  1 file changed, 8 insertions(+), 1 deletion(-)
> > 
> > diff --git a/fs/xfs/libxfs/xfs_attr.c b/fs/xfs/libxfs/xfs_attr.c
> > index ce4a34a..2588c73 100644
> > --- a/fs/xfs/libxfs/xfs_attr.c
> > +++ b/fs/xfs/libxfs/xfs_attr.c
> > @@ -511,7 +511,14 @@ xfs_attr_shortform_addname(xfs_da_args_t *args)
> >  		if (args->flags & ATTR_CREATE)
> >  			return retval;
> >  		retval = xfs_attr_shortform_remove(args);
> > -		ASSERT(retval == 0);
> > +		if (retval)
> > +			return retval;
> > +		/*
> > +		 * Since we have removed the old attr here,
> > +		 * further lookup will fail with ENOATTR.
> > +		 * Ignore this was a replace and go on creating new attr.
> 
> The last line of that comment doesn't make sense to me. not sure
> what it's meant to say...

That was what was in the patch attached to the bugzilla. :)

How about:

/*
 * Since we have removed the old attr, clear ATTR_REPLACE so that the
 * leaf format add routine won't trip over the attr not being around.
 */

instead?

--D


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