Subject: Re: linux-next: build warning after merge of the xfs tree

From: Brian Foster <[email-masked]>
Date: Thu, 31 Aug 2017 11:22:20 -0400

On Thu, Aug 31, 2017 at 07:57:52AM -0700, Darrick J. Wong wrote:
> On Thu, Aug 31, 2017 at 06:30:41AM -0400, Brian Foster wrote:
> > On Thu, Aug 31, 2017 at 10:07:03AM +1000, Stephen Rothwell wrote:
> > > Hi all,
> > > 
> > > After merging the xfs tree, today's linux-next build (powerpc
> > > ppc64_defconfig) produced this warning:
> > > 
> > > fs/xfs/xfs_buf_item.c: In function 'xfs_buf_item_unlock':
> > > fs/xfs/xfs_buf_item.c:573:9: warning: unused variable 'ordered' [-Wunused-variable]
> > >   bool   ordered = !!(bip->bli_flags & XFS_BLI_ORDERED);
> > >          ^
> > > 
> > > Introduced by commit
> > > 
> > >   a097077ef708 ("xfs: remove unnecessary dirty bli format check for ordered bufs")
> > > 
> > 
> > Ugh, this is due to the refactoring of this patch between v1 and v2. I
> > specifically recall testing for this in v1 because I added the ordered
> > bool purely to clean up the ASSERT(), then I apparently lost of track of
> > it for v2.
> > 
> > Anyways.. Christoph, Darrick, preferences to clean this up..? I have no
> > preference between the v1 or v2 factoring. Or if it's easier, we could
> > always just drop something like the hunk below on top. Thoughts?
> > 
> > Brian
> > 
> > --- 8< ---
> > 
> > diff --git a/fs/xfs/xfs_buf_item.c b/fs/xfs/xfs_buf_item.c
> > index ef2c137..f5d25f5 100644
> > --- a/fs/xfs/xfs_buf_item.c
> > +++ b/fs/xfs/xfs_buf_item.c
> > @@ -567,10 +567,15 @@ xfs_buf_item_unlock(
> >  {
> >  	struct xfs_buf_log_item	*bip = BUF_ITEM(lip);
> >  	struct xfs_buf		*bp = bip->bli_buf;
> > -	bool			aborted = !!(lip->li_flags & XFS_LI_ABORTED);
> > -	bool			hold = !!(bip->bli_flags & XFS_BLI_HOLD);
> > -	bool			dirty = !!(bip->bli_flags & XFS_BLI_DIRTY);
> > -	bool			ordered = !!(bip->bli_flags & XFS_BLI_ORDERED);
> > +	bool			aborted;
> > +	bool			hold;
> > +	bool			dirty;
> > +	bool			ordered;
> > +
> > +	aborted = !!(lip->li_flags & XFS_LI_ABORTED);
> > +	hold = !!(bip->bli_flags & XFS_BLI_HOLD);
> > +	dirty = !!(bip->bli_flags & XFS_BLI_DIRTY);
> > +	ordered = !!(bip->bli_flags & XFS_BLI_ORDERED);
> 
> The trouble is, 'ordered' is still an unused variable on !DEBUG builds,
> since the only user of ordered is that ASSERT.  So either we #ifdef
> DEBUG the variable out of existence or employ one of those silly
> 'ordered = ordered' constructions to shut up gcc, if that even still
> works.
> 

The warning goes away for me if we separate the initialization of
ordered from the declaration. Do you observe otherwise?

Brian

> --D
> 
> >  
> >  	/* Clear the buffer's association with this transaction. */
> >  	bp->b_transp = NULL;
> > --
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