Re: [PATCH] Btrfs: fix unexpected balance crash due to BUG_ON

[Liu Bo <bo.li.liu@oracle.com>]

On Fri, Jul 08, 2016 at 06:05:16PM +0200, David Sterba wrote:
> On Tue, May 03, 2016 at 04:30:54PM -0700, Liu Bo wrote:
> > > Just a heads up that this seems to introduce a valid warning, since it now
> > > can goto error before the first initializing use of path:
> > > 
> > > fs/btrfs/volumes.c: In function 'btrfs_balance':
> > > fs/btrfs/volumes.c:3601:2: warning: 'path' may be used uninitialized
> > > in this function [-Wmaybe-uninitialized]
> > >   btrfs_free_path(path);
> > >   ^
> > > fs/btrfs/volumes.c:3385:21: note: 'path' was declared here
> > >   struct btrfs_path *path;
> > >                      ^
> > > (it's really in __btrfs_balance which got inlined, so gcc thinks it's
> > > at the call site).
> > > 
> > > Simply setting path = NULL at the beginning of __btrfs_balance fixes it, since
> > > btrfs_free_path allows NULL values.
> > 
> > That's right, it's weird that I didn't get this warning while testing it.
> > 
> > Thanks for catching it, Holger.
> 
> Please send a v2, the patch is desiable.

Oh, I almost forgot this one, thanks for the reminder.

Thanks,

-liubo