On Thu, Apr 11, 2019 at 11:34:40AM +1000, Tobin C. Harding wrote:
> +/*
> + * d_isolate() - Dentry isolation callback function.
> + * @s: The dentry cache.
> + * @v: Vector of pointers to the objects to isolate.
> + * @nr: Number of objects in @v.
> + *
> + * The slab allocator is holding off frees. We can safely examine
> + * the object without the danger of it vanishing from under us.
> + */
> +static void *d_isolate(struct kmem_cache *s, void **v, int nr)
> +{
> + struct dentry *dentry;
> + int i;
> +
> + for (i = 0; i < nr; i++) {
> + dentry = v[i];
> + __dget(dentry);
> + }
> +
> + return NULL; /* No need for private data */
> +}
Huh? This is compeletely wrong; what you need is collecting the ones
with zero refcount (and not on shrink lists) into a private list.
*NOT* bumping the refcounts at all. And do it in your isolate thing.
> +static void d_partial_shrink(struct kmem_cache *s, void **v, int nr,
> + int node, void *_unused)
> +{
> + struct dentry *dentry;
> + LIST_HEAD(dispose);
> + int i;
> +
> + for (i = 0; i < nr; i++) {
> + dentry = v[i];
> + spin_lock(&dentry->d_lock);
> + dentry->d_lockref.count--;
> +
> + if (dentry->d_lockref.count > 0 ||
> + dentry->d_flags & DCACHE_SHRINK_LIST) {
> + spin_unlock(&dentry->d_lock);
> + continue;
> + }
> +
> + if (dentry->d_flags & DCACHE_LRU_LIST)
> + d_lru_del(dentry);
> +
> + d_shrink_add(dentry, &dispose);
> +
> + spin_unlock(&dentry->d_lock);
> + }
Basically, that loop (sans jerking the refcount up and down) should
get moved into d_isolate().
> +
> + if (!list_empty(&dispose))
> + shrink_dentry_list(&dispose);
> +}
... with this left in d_partial_shrink(). And you obviously need some way
to pass the list from the former to the latter...
