+}
+
+struct thread_deferred_req {
+ struct cache_deferred_req handle;
+ struct completion completion;
+};
+
+static void cache_restart_thread(struct cache_deferred_req *dreq, int too_many)
+{
+ struct thread_deferred_req *dr =
+ container_of(dreq, struct thread_deferred_req, handle);
+ complete(&dr->completion);
+}
+
+static void cache_wait_req(struct cache_req *req, struct cache_head *item)
+{
+ struct thread_deferred_req sleeper;
+ struct cache_deferred_req *dreq = &sleeper.handle;
+
+ sleeper.completion = COMPLETION_INITIALIZER_ONSTACK(sleeper.completion);
+ dreq->revisit = cache_restart_thread;
+
+ setup_deferral(dreq, item, 0);
+
+ if (!test_bit(CACHE_PENDING, &item->flags) ||
+ wait_for_completion_interruptible_timeout(
+ &sleeper.completion, req->thread_wait) <= 0) {
+ /* The completion wasn't completed, so we need
+ * to clean up
+ */
+ spin_lock(&cache_defer_lock);
+ if (!hlist_unhashed(&sleeper.handle.hash)) {
+ __unhash_deferred_req(&sleeper.handle);
+ spin_unlock(&cache_defer_lock);
+ } else {
+ /* cache_revisit_request already removed
+ * this from the hash table, but hasn't
+ * called ->revisit yet. It will very soon
+ * and we need to wait for it.
+ */
+ spin_unlock(&cache_defer_lock);
+ wait_for_completion(&sleeper.completion);
+ }
+ }
+}
+
+static void cache_limit_defers(void)
+{
+ /* Make sure we haven't exceed the limit of allowed deferred
+ * requests.
+ */
+ struct cache_deferred_req *discard = NULL;
+
+ if (cache_defer_cnt <= DFR_MAX)
+ return;
+
+ spin_lock(&cache_defer_lock);
+
+ /* Consider removing either the first or the last */
+ if (cache_defer_cnt > DFR_MAX) {
+ if (net_random() & 1)
+ discard = list_entry(cache_defer_list.next,
+ struct cache_deferred_req, recent);
+ else
+ discard = list_entry(cache_defer_list.prev,
+ struct cache_deferred_req, recent);
+ __unhash_deferred_req(discard);
+ }
+ spin_unlock(&cache_defer_lock);