Hongyi Jia <jiayis...@gmail.com> wrote:

> +bool __fscache_check_consistency(struct fscache_cookie *cookie)
> +{
> +     struct fscache_object *object;
> +
> +     if (cookie->def->type != FSCACHE_COOKIE_TYPE_DATAFILE)
> +             return false;
> +
> +     if (hlist_empty(&cookie->backing_objects))
> +             return false;
> +
> +     object = hlist_entry(cookie->backing_objects.first,
> +                     struct fscache_object, cookie_link);
> +
> +     return object->cache->ops->check_consistency(object);
> +}

Hmmm...  This isn't actually safe.  You have to either:

 (1) hold cookie->lock whilst touching the object pointer when coming from the
     netfs side, or:

 (2) set up an operation to do this (as, say, __fscache_alloc_page() does).

The problem is that you have nothing to defend against the object being
withdrawn by the cache under you.

David
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