Re: nfslocalio: use correct wait address in nfs_uuid_put()

[Mike Snitzer <snitzer@kernel.org>]

On Mon, Jul 14, 2025 at 01:56:13PM +1000, NeilBrown wrote:
> 
> This wait_var_event_spinlock() in nfs_uuid_put() is waiting for the
> wakeup signalled at the end of nfs_close_local_fh().  That
> wake_up_var_locked() uses &nfl->nfs_uuid, so the waiter must use the
> same address, else nfs_uuid_put() could wait indefinitely causing
> various problems.
> 
> Fixes: 21fb44034695 ("nfs_localio: protect race between nfs_uuid_put() and nfs_close_local_fh()")
> Reported-by: Mike Snitzer <snitzer@kernel.org>
> Signed-off-by: NeilBrown <neil@brown.name>
> ---
>  fs/nfs_common/nfslocalio.c | 2 +-
>  1 file changed, 1 insertion(+), 1 deletion(-)
> 
> diff --git a/fs/nfs_common/nfslocalio.c b/fs/nfs_common/nfslocalio.c
> index 05c7c16e37ab..bc8dcfb256a3 100644
> --- a/fs/nfs_common/nfslocalio.c
> +++ b/fs/nfs_common/nfslocalio.c
> @@ -177,7 +177,7 @@ static bool nfs_uuid_put(nfs_uuid_t *nfs_uuid)
>  			/* nfs_close_local_fh() is doing the
>  			 * close and we must wait. until it unlinks
>  			 */
> -			wait_var_event_spinlock(nfl,
> +			wait_var_event_spinlock(&nfl->nfs_uuid,
>  						list_first_entry_or_null(
>  							&nfs_uuid->files,
>  							struct nfs_file_localio,
> -- 
> 2.49.0
> 
> 

Makes sense:

Acked-by: Mike Snitzer <snitzer@kernel.org>

And I _will_ try to get this tested at the scale I was able to test
late last week.  Will let you and others know (hopefully within the
next 24h).

Mike