Re: [PATCH v2] vfs: avoid dereferencing pointers in iterate_supers callbacks

[Matthew Wilcox]

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);