On 7/19/22 07:06, Christoph Hellwig wrote:

On Mon, Jul 18, 2022 at 11:20:39AM -0700, Song Liu wrote:

quoted

quoted

quoted

   static inline struct mddev *mddev_get(struct mddev *mddev)
   {
+     lockdep_assert_held(&all_mddevs_lock);
+
+     if (mddev->deleted)
+             return NULL;
       atomic_inc(&mddev->active);
       return mddev;
   }

Why can't we use 'atomic_inc_unless_zero' here and do away with the
additional 'deleted' flag?

quoted

I think atomic_inc_unless_zero() should work here. Alternatively, we can
also grab a big from mddev->flags as MD_DELETED.

s/big/bit/ ?

Yes, this could use mddev->flags.  I don't think atomic_inc_unless_zero
would work, as an array can have a refcount of 0 but we still allow
to take new references to it, the deletion only happens if the other
conditions in mddev_put are met.

Do you want me to repin the series using a flag?

I would vote for it.

Cheers,

Hannes