Re: [PATCH] xfs: fix uninit warning in xfs_growfs_data

["Darrick J. Wong" <djwong@kernel.org>]

On Fri, Jul 07, 2023 at 08:54:10AM +1000, Dave Chinner wrote:
> On Wed, Jul 05, 2023 at 07:26:30PM -0700, Darrick J. Wong wrote:
> > From: Darrick J. Wong <djwong@kernel.org>
> > 
> > Quiet down this gcc warning:
> > 
> > fs/xfs/xfs_fsops.c: In function ‘xfs_growfs_data’:
> > fs/xfs/xfs_fsops.c:219:21: error: ‘lastag_extended’ may be used uninitialized in this function [-Werror=maybe-uninitialized]
> >   219 |                 if (lastag_extended) {
> >       |                     ^~~~~~~~~~~~~~~
> > fs/xfs/xfs_fsops.c:100:33: note: ‘lastag_extended’ was declared here
> >   100 |         bool                    lastag_extended;
> >       |                                 ^~~~~~~~~~~~~~~
> > 
> > By setting its value explicitly.  From code analysis I don't think this
> > is a real problem, but I have better things to do than analyse this
> > closely.
> 
> Huh. What compiler is complaining about that?

gcc 11.3, though oddly this only happens when I turn on gcov.  Not sure
what sorcery gets enabled with that, but it got in the way of teaching
the fstests cloud to spit out 60MB(!) of coverage reports for each
fstests run, and the source code fix seemed obvious.

> 
> > Signed-off-by: Darrick J. Wong <djwong@kernel.org>
> > ---
> >  fs/xfs/xfs_fsops.c |    2 +-
> >  1 file changed, 1 insertion(+), 1 deletion(-)
> > 
> > diff --git a/fs/xfs/xfs_fsops.c b/fs/xfs/xfs_fsops.c
> > index 65473bc52c7d..96edc87bf030 100644
> > --- a/fs/xfs/xfs_fsops.c
> > +++ b/fs/xfs/xfs_fsops.c
> > @@ -97,7 +97,7 @@ xfs_growfs_data_private(
> >  	xfs_agnumber_t		nagimax = 0;
> >  	xfs_rfsblock_t		nb, nb_div, nb_mod;
> >  	int64_t			delta;
> > -	bool			lastag_extended;
> > +	bool			lastag_extended = false;
> >  	xfs_agnumber_t		oagcount;
> >  	struct xfs_trans	*tp;
> >  	struct aghdr_init_data	id = {};
> 
> Looks good,
> 
> Reviewed-by: Dave Chinner <dchinner@redhat.com>

Thanks!

--D

> Dave Chinner
> david@fromorbit.com