mio: Initialize mio mpool only for non-volatile caches

The mpool is allocated on creation of the first non-volatile cache,
and deallocated on destruction of the last non-volatile cache.

Signed-off-by: Robert Baldyga <robert.baldyga@unvertical.com>

Author: robertbaldyga

src/metadata/metadata_io.c

@@ -1,6 +1,7 @@
 /*
  * Copyright(c) 2012-2022 Intel Corporation
  * Copyright(c) 2024 Huawei Technologies
+ * Copyright(c) 2026 Unvertical
  * SPDX-License-Identifier: BSD-3-Clause
  */
 #include "metadata.h"
@@ -230,7 +231,7 @@ static void metadata_io_req_finalize(struct metadata_io_request *m_req)
 	struct metadata_io_request_asynch *a_req = m_req->asynch;
 
 	if (env_atomic_dec_return(&a_req->req_active) == 0)
-		env_mpool_del(m_req->cache->owner->resources.mio, a_req,
+		env_mpool_del(m_req->cache->owner->resources.mio.mpool, a_req,
 				a_req->alloc_req_count);
 }
 
@@ -388,7 +389,7 @@ static int metadata_io_i_asynch(ocf_cache_t cache, ocf_queue_t queue, int dir,
 	uint32_t io_count = OCF_DIV_ROUND_UP(count, max_count);
 	uint32_t req_count = OCF_MIN(io_count, METADATA_IO_REQS_LIMIT);
 	int i;
-	struct env_mpool *mio_allocator = cache->owner->resources.mio;
+	struct env_mpool *mio_allocator = cache->owner->resources.mio.mpool;
 
 	if (count == 0)
 		return 0;
@@ -483,29 +484,49 @@ int metadata_io_read_i_asynch(ocf_cache_t cache, ocf_queue_t queue,
 					       not exceed one page (4096B).
 					       Change if apropriate. */
 
-int ocf_metadata_io_ctx_init(struct ocf_ctx *ocf_ctx)
+int ocf_metadata_io_open(struct ocf_ctx *ocf_ctx)
 {
 	uint32_t limits[] = {
 		[0 ... MIO_RPOOL_THRESHOLD - 1] = -1,
 		[MIO_RPOOL_THRESHOLD ... ocf_mio_size_max - 1] = MIO_RPOOL_LIMIT,
 		[ocf_mio_size_max ... env_mpool_max] = -1,
 	};
 
-	ocf_ctx->resources.mio = env_mpool_create(
+	if (ocf_ctx->resources.mio.ref_count > 0)
+		goto out;
+
+	ocf_ctx->resources.mio.mpool = env_mpool_create(
 			sizeof(struct metadata_io_request_asynch),
 			sizeof(struct metadata_io_request),
 			ENV_MEM_NOIO, ocf_mio_size_max - 1, true,
 			limits,
 			"ocf_mio",
 			true);
-	if (ocf_ctx->resources.mio == NULL)
-		return -1;
+	if (ocf_ctx->resources.mio.mpool == NULL)
+		return -OCF_ERR_NO_MEM;
+
+out:
+	ocf_ctx->resources.mio.ref_count++;
+	return 0;
+}
+
+void ocf_metadata_io_close(struct ocf_ctx *ocf_ctx)
+{
+	if (--ocf_ctx->resources.mio.ref_count == 0) {
+		env_mpool_destroy(ocf_ctx->resources.mio.mpool);
+		ocf_ctx->resources.mio.mpool = NULL;
+	}
+}
+
+int ocf_metadata_io_ctx_init(struct ocf_ctx *ocf_ctx)
+{
+	ocf_ctx->resources.mio.mpool = NULL;
+	ocf_ctx->resources.mio.ref_count = 0;
 
 	return 0;
 }
 
 void ocf_metadata_io_ctx_deinit(struct ocf_ctx *ocf_ctx)
 {
-	env_mpool_destroy(ocf_ctx->resources.mio);
-	ocf_ctx->resources.mio = NULL;
+	ENV_BUG_ON(ocf_ctx->resources.mio.ref_count != 0);
 }

src/metadata/metadata_io.h

@@ -1,13 +1,15 @@
 /*
  * Copyright(c) 2012-2021 Intel Corporation
  * Copyright(c) 2024 Huawei Technologies
+ * Copyright(c) 2026 Unvertical
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
 #ifndef __METADATA_IO_H__
 #define __METADATA_IO_H__
 
 #include "../concurrency/ocf_mio_concurrency.h"
+#include "metadata_io_resource.h"
 
 /**
  * @file metadata_io.h
@@ -146,14 +148,4 @@ int metadata_io_read_i_asynch(ocf_cache_t cache, ocf_queue_t queue,
 		ocf_metadata_io_event_t drain_hndl,
 		ocf_metadata_io_end_t compl_hndl);
 
-/**
- * Initialize ocf_ctx related structures of metadata_io (mpool).
- */
-int ocf_metadata_io_ctx_init(struct ocf_ctx *ocf_ctx);
-
-/**
- * Deinitialize ocf_ctx related structures of metadata_io
- */
-void ocf_metadata_io_ctx_deinit(struct ocf_ctx *ocf_ctx);
-
-#endif /* METADATA_IO_UTILS_H_ */
+#endif /* __METADATA_IO_H__ */

src/metadata/metadata_io_resource.h

@@ -0,0 +1,42 @@
+/*
+ * Copyright(c) 2012-2021 Intel Corporation
+ * Copyright(c) 2026 Unvertical
+ * SPDX-License-Identifier: BSD-3-Clause
+ */
+
+#ifndef __METADATA_IO_RESOURCE_H__
+#define __METADATA_IO_RESOURCE_H__
+
+/*
+ * ocf_ctx resource
+ */
+struct ocf_metadata_io_resource {
+	struct env_mpool *mpool;
+	int ref_count;
+};
+
+/**
+ * Initialize ocf_ctx related structures of metadata_io.
+ */
+int ocf_metadata_io_ctx_init(struct ocf_ctx *ocf_ctx);
+
+/**
+ * Deinitialize ocf_ctx related structures of metadata_io
+ */
+void ocf_metadata_io_ctx_deinit(struct ocf_ctx *ocf_ctx);
+
+/**
+ * Initialize per-ocf_ctx mio resources
+ *
+ * Can be safely called multiple times - refcount based.
+ */
+int ocf_metadata_io_open(struct ocf_ctx *ocf_ctx);
+
+/**
+ * Decrements the refcount of per-ocf_ctx mio resources
+ *
+ * Needs to be called as many times as ocf_metadata_io_open().
+ */
+void ocf_metadata_io_close(struct ocf_ctx *ocf_ctx);
+
+#endif /* __METADATA_IO_RESOURCE_H__ */

src/mngt/ocf_mngt_cache.c

@@ -1631,6 +1631,14 @@ static int _ocf_mngt_cache_start(ocf_ctx_t ctx, ocf_cache_t *cache,
 		goto _cache_mngt_init_instance_ERROR;
 	}
 
+	if (!cfg->metadata_volatile) {
+		result = ocf_metadata_io_open(ctx);
+		if (result) {
+			env_rmutex_unlock(&ctx->lock);
+			goto _cache_mngt_init_instance_ERROR;
+		}
+	}
+
 	list_add_tail(&tmp_cache->list, &ctx->caches);
 	env_rmutex_unlock(&ctx->lock);
 
@@ -2335,6 +2343,9 @@ static void _ocf_mngt_cache_dealloc(void *priv)
 	ctx = cache->owner;
 	ocf_metadata_deinit(cache);
 
+	if (!cache->metadata.is_volatile)
+		ocf_metadata_io_close(ctx);
+
 	env_refcnt_deinit(&cache->refcnt.cache);
 	env_refcnt_deinit(&cache->refcnt.dirty);
 	env_refcnt_deinit(&cache->refcnt.metadata);

src/ocf_ctx_priv.h

@@ -1,5 +1,6 @@
 /*
  * Copyright(c) 2012-2022 Intel Corporation
+ * Copyright(c) 2026 Unvertical
  * SPDX-License-Identifier: BSD-3-Clause
  */
 
@@ -11,6 +12,7 @@
 #include "ocf/ocf_composite_volume.h"
 #include "ocf_logger_priv.h"
 #include "ocf_volume_priv.h"
+#include "metadata/metadata_io_resource.h"
 
 #define OCF_VOLUME_TYPE_CNT_USER 8
 #define OCF_VOLUME_TYPE_CNT_PRIV 3
@@ -38,7 +40,7 @@ struct ocf_ctx {
 	const struct ocf_ctx_ops *ops;
 	struct {
 		struct env_mpool *req;
-		struct env_mpool *mio;
+		struct ocf_metadata_io_resource mio;
 	} resources;
 	struct list_head caches;
 	struct {