Add promotion policy API and use it in I/O path

Promotion policy is supposed to perform ALRU noise filtering by
eliminating one-hit wonders being added to cache and polluting it.

Signed-off-by: Jan Musial <jan.musial@intel.com>

src/promotion/promotion.c

@@ -0,0 +1,99 @@
+/*
+ * Copyright(c) 2019 Intel Corporation
+ * SPDX-License-Identifier: BSD-3-Clause-Clear
+ */
+
+#include "../metadata/metadata.h"
+
+#include "promotion.h"
+#include "ops.h"
+#include "nhit.h"
+
+struct promotion_policy_ops ocf_promotion_policies[ocf_promotion_max] = {
+	[ocf_promotion_nop] = {
+		.name = "nop",
+	},
+	[ocf_promotion_nhit] = {
+		.name = "nhit",
+		.init = nhit_init,
+		.deinit = nhit_deinit,
+		.set_param = nhit_set_param,
+		.req_purge = nhit_req_purge,
+		.req_should_promote = nhit_req_should_promote,
+	},
+};
+
+ocf_error_t ocf_promotion_init(ocf_cache_t cache, ocf_promotion_policy_t *policy)
+{
+	ocf_promotion_t type = cache->conf_meta->promotion_policy_type;
+	ocf_error_t result = 0;
+
+	ENV_BUG_ON(type >= ocf_promotion_max);
+
+	*policy = env_vmalloc(sizeof(**policy));
+	if (!*policy)
+		return -OCF_ERR_NO_MEM;
+
+	(*policy)->type = type;
+
+	if (ocf_promotion_policies[type].init)
+		result = ocf_promotion_policies[type].init(cache, *policy);
+
+	return result;
+}
+
+void ocf_promotion_deinit(ocf_promotion_policy_t policy)
+{
+	ocf_promotion_t type = policy->type;
+
+	ENV_BUG_ON(type >= ocf_promotion_max);
+
+	if (ocf_promotion_policies[type].deinit)
+		ocf_promotion_policies[type].deinit(policy);
+
+	env_vfree(policy);
+}
+
+ocf_error_t ocf_promotion_set_param(ocf_promotion_policy_t policy,
+		uint8_t param_id, uint64_t param_value)
+{
+	ocf_promotion_t type = policy->type;
+	ocf_error_t result = 0;
+
+	ENV_BUG_ON(type >= ocf_promotion_max);
+
+	if (ocf_promotion_policies[type].set_param) {
+		result = ocf_promotion_policies[type].set_param(policy, param_id,
+				param_value);
+	}
+
+	return result;
+}
+
+void ocf_promotion_req_purge(ocf_promotion_policy_t policy,
+		struct ocf_request *req)
+{
+	ocf_promotion_t type = policy->type;
+
+	ENV_BUG_ON(type >= ocf_promotion_max);
+
+	if (ocf_promotion_policies[type].req_purge)
+		ocf_promotion_policies[type].req_purge(policy, req);
+}
+
+bool ocf_promotion_req_should_promote(ocf_promotion_policy_t policy,
+		struct ocf_request *req)
+{
+	ocf_promotion_t type = policy->type;
+	bool result = true;
+
+	ENV_BUG_ON(type >= ocf_promotion_max);
+
+	if (ocf_promotion_policies[type].req_should_promote) {
+		result = ocf_promotion_policies[type].req_should_promote(policy,
+				req);
+	}
+
+	return result;
+}
+