Try closing channels for failed ops

src/main/java/com/emc/mongoose/storage/driver/coop/netty/NettyStorageDriverBase.java

@@ -419,15 +419,15 @@ protected int submit(final List<O> ops, final int from, final int to)
 			LogUtil.exception(Level.WARN, e, "Failed to lease the connection for the load operation");
 			nextOp.status(Operation.Status.FAIL_IO);
 			complete(conn, nextOp);
-			if (permits - n - 1 > 0) {
+			if (permits - n > 1) {
 				concurrencyThrottle.release(permits - n - 1);
 			}
 		} catch (final Throwable thrown) {
 			throwUncheckedIfInterrupted(thrown);
 			LogUtil.exception(Level.WARN, thrown, "Failed to submit the load operations");
 			nextOp.status(Operation.Status.FAIL_UNKNOWN);
 			complete(conn, nextOp);
-			if (permits - n - 1 > 0) {
+			if (permits - n > 1) {
 				concurrencyThrottle.release(permits - n - 1);
 			}
 		}
@@ -595,6 +595,9 @@ public void complete(final Channel channel, final O op) {
 		} catch (final IllegalStateException e) {
 			LogUtil.exception(Level.DEBUG, e, "{}: invalid load operation state", op.toString());
 		}
+		if (op.status() != Operation.Status.SUCC) {
+			channel.close();
+		}
 		if (!channel.attr(ATTR_KEY_RELEASED).get()) {
 			concurrencyThrottle.release();
 			if (channel != null) {