os/bluestore: wake kv thread when blocking on deferred_bytes

We need to wake the kv thread whenever setting deferred_aggressive to
ensure that txns with deferred io that have committed but haven't submitted
their deferred writes get submitted.  This aligns us with the other
users of deferred_aggressive (e.g., _osr_drain_all).

Signed-off-by: Sage Weil <sage@redhat.com>

src/os/bluestore/BlueStore.cc

@@ -8951,6 +8951,11 @@ int BlueStore::queue_transactions(
 	       << dendl;
       ++deferred_aggressive;
       deferred_try_submit();
+      {
+	// wake up any previously finished deferred events
+	std::lock_guard<std::mutex> l(kv_lock);
+	kv_cond.notify_one();
+      }
       throttle_deferred_bytes.get(txc->cost);
       --deferred_aggressive;
    }