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);