linux-kernel - Re: [PATCH v2] vfs: avoid dereferencing pointers in iterate

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Message-ID: <49934b3d13263360fbf26bc56de2914db0b3513a.camel@kernel.org>
Date:   Thu, 17 May 2018 14:55:36 -0400
From:   Jeff Layton <jlayton@...nel.org>
To:     Matthew Wilcox <willy@...radead.org>
Cc:     viro@...iv.linux.org.uk, jack@...e.com,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        lurodriguez@...e.de
Subject: Re: [PATCH v2] vfs: avoid dereferencing pointers in iterate_supers
 callbacks

On Thu, 2018-05-17 at 11:26 -0700, Matthew Wilcox wrote:
> On Thu, May 17, 2018 at 01:43:36PM -0400, Jeff Layton wrote:
> > @@ -107,12 +109,10 @@ static void fdatawait_one_bdev(struct block_device *bdev, void *arg)
> >   */
> >  void ksys_sync(void)
> >  {
> > -	int nowait = 0, wait = 1;
> > -
> >  	wakeup_flusher_threads(WB_REASON_SYNC);
> >  	iterate_supers(sync_inodes_one_sb, NULL);
> > -	iterate_supers(sync_fs_one_sb, &nowait);
> > -	iterate_supers(sync_fs_one_sb, &wait);
> > +	iterate_supers(sync_fs_one_sb, NULL);
> > +	iterate_supers(sync_fs_one_sb, (void *)1UL);
> 
> I think this is actually less clear.  How about:
> 
> 	void *wait = (void *)1UL;
> 
> 	iterate_supers(sync_fs_one_sb, !wait);
> 	iterate_supers(sync_fs_one_sb, wait);
> 

Sure, I could do that. We could also keep the wait/nowait vars too, I
guess.