ocf/src/engine/engine_rd.c

/*
 * Copyright(c) 2012-2022 Intel Corporation
 * Copyright(c) 2024-2025 Huawei Technologies
 * SPDX-License-Identifier: BSD-3-Clause
 */

#include "ocf/ocf.h"
#include "../ocf_cache_priv.h"
#include "engine_rd.h"
#include "engine_pt.h"
#include "engine_inv.h"
#include "engine_bf.h"
#include "engine_common.h"
#include "engine_io.h"
#include "cache_engine.h"
#include "../concurrency/ocf_concurrency.h"
#include "../ocf_request.h"
#include "../utils/utils_cache_line.h"
#include "../utils/utils_user_part.h"
#include "../metadata/metadata.h"
#include "../ocf_def_priv.h"

#define OCF_ENGINE_DEBUG_IO_NAME "rd"
#include "engine_debug.h"

static void _ocf_read_generic_hit_complete(struct ocf_request *req, int error)
{
	struct ocf_alock *c = ocf_cache_line_concurrency(
			req->cache);

	OCF_DEBUG_RQ(req, "HIT completion");

	if (error) {
		ocf_core_stats_cache_error_update(req->core, OCF_READ);
		inc_fallback_pt_error_counter(req->cache);
		ocf_queue_push_req_pt(req);
	} else {
		ocf_req_unlock(c, req);
		req->complete(req, error);
		ocf_req_put(req);
	}
}

static void _ocf_read_generic_miss_complete(struct ocf_request *req, int error)
{
	struct ocf_cache *cache = req->cache;

	OCF_DEBUG_RQ(req, "MISS completion");

	if (error) {
		/* --- Do not backfill --- */
		req->complete(req, error);

		ocf_core_stats_core_error_update(req->core, OCF_READ);

		ctx_data_free(cache->owner, req->cp_data);
		req->cp_data = NULL;

		/* Invalidate metadata */
		ocf_engine_invalidate(req);

		return;
	}

	/* Copy data to the backfill buffer */
	if (req->cp_data) {
		ctx_data_cpy(cache->owner, req->cp_data, req->data, 0, 0,
				req->bytes);
	}

	req->complete(req, error);

	ocf_engine_backfill(req);
}

void ocf_read_generic_submit_hit(struct ocf_request *req)
{
	ocf_engine_forward_cache_io_req(req, OCF_READ,
			_ocf_read_generic_hit_complete);
}

static inline void _ocf_read_generic_submit_miss(struct ocf_request *req)
{
	struct ocf_cache *cache = req->cache;
	int ret;

	req->cp_data = ctx_data_alloc(cache->owner,
			BYTES_TO_PAGES(req->bytes));
	if (!req->cp_data) {
		/* If buffer allocation for backfill fails, ignore the error */
		ocf_cache_log(cache, log_warn, "Backfill buffer allocation "
				"error (size %u)\n",
				req->bytes);
		goto err_alloc;
	}

	ret = ctx_data_mlock(cache->owner, req->cp_data);
	if (ret) {
		ocf_cache_log(cache, log_warn, "Backfill error\n");
		ctx_data_free(cache->owner, req->cp_data);
		req->cp_data = NULL;
	}

err_alloc:
	ocf_engine_forward_core_io_req(req, _ocf_read_generic_miss_complete);
}

static int _ocf_read_generic_do(struct ocf_request *req)
{
	if (ocf_engine_is_miss(req) && req->alock_rw == OCF_READ) {
		/* Miss can be handled only on write locks.
		 * Need to switch to PT
		 */
		OCF_DEBUG_RQ(req, "Switching to PT");
		ocf_read_pt_do(req);
		return 0;
	}

	/* Get OCF request - increase reference counter */
	ocf_req_get(req);

	if (ocf_engine_is_miss(req)) {
		if (req->info.dirty_any) {
			ocf_hb_req_prot_lock_rd(req);

			/* Request is dirty need to clean request */
			ocf_engine_clean(req);

			ocf_hb_req_prot_unlock_rd(req);

			/* We need to clean request before processing, return */
			ocf_req_put(req);

			return 0;
		}
	}

	if (ocf_engine_needs_repart(req)) {
		OCF_DEBUG_RQ(req, "Re-Part");

		ocf_hb_req_prot_lock_wr(req);

		/* Probably some cache lines are assigned into wrong
		 * partition. Need to move it to new one
		 */
		ocf_user_part_move(req);

		ocf_hb_req_prot_unlock_wr(req);
	}

	OCF_DEBUG_RQ(req, "Submit");

	/* Submit IO */
	if (ocf_engine_is_hit(req))
		ocf_read_generic_submit_hit(req);
	else
		_ocf_read_generic_submit_miss(req);

	/* Update statistics */
	ocf_engine_update_request_stats(req);
	ocf_engine_update_block_stats(req);

	/* Put OCF request - decrease reference counter */
	ocf_req_put(req);

	return 0;
}

static const struct ocf_engine_callbacks _rd_engine_callbacks =
{
	.resume = ocf_engine_on_resume,
};

int ocf_read_generic(struct ocf_request *req)
{
	int lock = OCF_LOCK_NOT_ACQUIRED;
	struct ocf_cache *cache = req->cache;


	if (env_atomic_read(&cache->pending_read_misses_list_blocked)) {
		/* There are conditions to bypass IO */
		req->force_pt = true;
		ocf_read_pt(req);
		return 0;
	}

	/* Get OCF request - increase reference counter */
	ocf_req_get(req);

	/* Set resume call backs */
	req->engine_handler = _ocf_read_generic_do;
	req->engine_cbs = &_rd_engine_callbacks;

	lock = ocf_engine_prepare_clines(req);

	if (!ocf_req_test_mapping_error(req)) {
		if (lock >= 0) {
			if (lock != OCF_LOCK_ACQUIRED) {
				/* Lock was not acquired, need to wait for resume */
				OCF_DEBUG_RQ(req, "NO LOCK");
			} else {
				/* Lock was acquired can perform IO */
				_ocf_read_generic_do(req);
			}
		} else {
			OCF_DEBUG_RQ(req, "LOCK ERROR %d", lock);
			req->complete(req, lock);
			ocf_req_put(req);
		}
	} else {
		ocf_req_clear(req);
		req->force_pt = true;
		ocf_read_pt(req);
	}


	/* Put OCF request - decrease reference counter */
	ocf_req_put(req);

	return 0;
}