> +static void brd_free_page_rcu(struct rcu_head *head)
> +{
> + struct page *page = container_of(head, struct page, rcu_head);
> + __free_page(page);
Nit: missing empty line here. Although I see no point in the local
variable anyay.
> +}
> +
> +static void brd_free_page(struct brd_device *brd, sector_t sector)
> +{
> + struct page *page;
> + pgoff_t idx;
> +
> + idx = sector >> PAGE_SECTORS_SHIFT;
> + page = xa_erase(&brd->brd_pages, idx);
> +
> + if (page) {
> + BUG_ON(page->index != idx);
> + call_rcu(&page->rcu_head, brd_free_page_rcu);
> + }
Doing one call_rcu per page is horribly inefficient. Please look into
batching this up.
> +static bool discard = false;
> +module_param(discard, bool, 0444);
> +MODULE_PARM_DESC(discard, "Support discard");
Doing this as a global paramter that can't even be changed at run time
does not feel very user friendly.
