DAOS-18929 cart: add refcounting of crt bulks

src/cart/crt_bulk.c

@@ -1,7 +1,7 @@
 /*
  * (C) Copyright 2016-2024 Intel Corporation.
  * (C) Copyright 2025 Google LLC
- * (C) Copyright 2025 Hewlett Packard Enterprise Development LP
+ * (C) Copyright 2025-2026 Hewlett Packard Enterprise Development LP
  *
  * SPDX-License-Identifier: BSD-2-Clause-Patent
  */
@@ -106,6 +106,7 @@ crt_bulk_create(crt_context_t crt_ctx, d_sg_list_t *sgl,
 	D_ALLOC_PTR(ret_hdl);
 	if (ret_hdl == NULL)
 		D_GOTO(out, rc = -DER_NOMEM);
+	ret_hdl->refcount = 1;
 
 	quota_rc = get_quota_resource(crt_ctx, CRT_QUOTA_BULKS);
 	if (quota_rc == -DER_QUOTA_LIMIT) {
@@ -183,19 +184,13 @@ crt_bulk_addref(crt_bulk_t crt_bulk)
 {
 	struct crt_bulk *bulk = crt_bulk;
 	int              rc   = -DER_SUCCESS;
-	hg_return_t      hg_ret;
 
 	if (bulk == NULL) {
 		D_ERROR("invalid parameter, NULL bulk\n");
 		D_GOTO(out, rc = -DER_INVAL);
 	}
 
-	hg_ret = HG_Bulk_ref_incr(bulk->hg_bulk_hdl);
-	if (hg_ret != HG_SUCCESS) {
-		D_ERROR("HG_Bulk_ref_incr failed, hg_ret: %d.\n", hg_ret);
-		rc = crt_hgret_2_der(hg_ret);
-	}
-
+	atomic_fetch_add(&bulk->refcount, 1);
 out:
 	return rc;
 }
@@ -204,40 +199,43 @@ int
 crt_bulk_free(crt_bulk_t crt_bulk)
 {
 	struct crt_bulk *bulk = crt_bulk;
-	int              rc   = -DER_SUCCESS;
-	hg_return_t      hg_ret;
 
 	if (bulk == NULL) {
 		D_ERROR("invalid parameter, NULL bulk\n");
-		D_GOTO(out, rc = -DER_INVAL);
+		return -DER_INVAL;
 	}
 
-	/* This can happen if D_QUOTA_BULKS is enabled on a client */
-	if (bulk->hg_bulk_hdl == HG_BULK_NULL) {
-		if (bulk->deferred) {
-			/* Treat as success */
-			D_GOTO(out, rc = DER_SUCCESS);
-		} else {
-			D_ASSERTF(0, "Bulk handle should not be NULL\n");
-		}
-	}
+	if (atomic_fetch_sub(&bulk->refcount, 1) > 1)
+		return DER_SUCCESS;
+
+	crt_bulk_free_common(bulk);
+
+	return DER_SUCCESS;
+}
 
-	hg_ret = HG_Bulk_free(bulk->hg_bulk_hdl);
-	if (hg_ret != HG_SUCCESS) {
-		D_ERROR("HG_Bulk_free failed, hg_ret: %d.\n", hg_ret);
-		rc = crt_hgret_2_der(hg_ret);
+void
+crt_bulk_free_common(struct crt_bulk *bulk)
+{
+	hg_return_t hg_ret;
+
+	D_ASSERT(bulk != NULL);
+
+	/* Free the underlying Mercury bulk handle */
+	if (bulk->hg_bulk_hdl != HG_BULK_NULL) {
+		hg_ret = HG_Bulk_free(bulk->hg_bulk_hdl);
+		if (hg_ret != HG_SUCCESS) {
+			D_ERROR("HG_Bulk_free() failed (%s)\n", HG_Error_to_string(hg_ret));
+			/* Ignore the error, as we are already in a cleanup path */
+		}
 	}
 
 	/* decoded bulks are not counted towards quota; such bulks have crt_ctx set to NULL */
-	if (bulk->crt_ctx)
+	if (!bulk->deferred && bulk->crt_ctx != NULL)
 		put_quota_resource(bulk->crt_ctx, CRT_QUOTA_BULKS);
-out:
-	if (bulk != NULL) {
-		if (bulk->iovs)
-			D_FREE(bulk->iovs);
-		D_FREE(bulk);
-	}
-	return rc;
+
+	if (bulk->iovs != NULL)
+		D_FREE(bulk->iovs);
+	D_FREE(bulk);
 }
 
 /* Helper function to check for bulk expiration */

src/cart/crt_hg_proc.c

@@ -1,7 +1,7 @@
 /*
  * (C) Copyright 2016-2024 Intel Corporation.
  * (C) Copyright 2025 Google LLC
- * (C) Copyright 2025 Hewlett Packard Enterprise Development LP
+ * (C) Copyright 2025-2026 Hewlett Packard Enterprise Development LP
  *
  * SPDX-License-Identifier: BSD-2-Clause-Patent
  */
@@ -115,12 +115,44 @@ CRT_PROC_TYPE_FUNC(int64_t)
 CRT_PROC_TYPE_FUNC(uint64_t)
 CRT_PROC_TYPE_FUNC(bool)
 
+static int
+crt_proc_crt_bulk_t_deferred(struct crt_bulk *bulk)
+{
+	struct crt_context *ctx;
+	int                 rc;
+
+	/* Create mercury handle based on saved params */
+	ctx = bulk->crt_ctx;
+	D_ASSERT(ctx != NULL);
+
+	rc = crt_hg_bulk_create(&ctx->cc_hg_ctx, &bulk->sgl, bulk->bulk_perm, &bulk->hg_bulk_hdl);
+	if (rc != DER_SUCCESS)
+		return rc;
+
+	record_quota_resource(ctx, CRT_QUOTA_BULKS);
+
+	if (bulk->bound) {
+		rc = crt_hg_bulk_bind(bulk->hg_bulk_hdl, &ctx->cc_hg_ctx);
+		if (rc != 0) {
+			DL_ERROR(rc, "Failed to bind bulk during proc");
+			/* free will return quota resource */
+				crt_bulk_free(bulk);
+			return rc;
+		}
+	}
+	/* Mark as no longer deferred once allocation is complete */
+	bulk->deferred = false;
+
+	return 0;
+}
+
 int
 crt_proc_crt_bulk_t(crt_proc_t proc, crt_proc_op_t proc_op, crt_bulk_t *pcrt_bulk)
 {
 	struct crt_bulk *bulk = NULL;
+	hg_bulk_t        hg_bulk;
 	hg_return_t      hg_ret;
-	hg_bulk_t        tmp_hg_bulk;
+	int              rc;
 
 	/*
 	 * We only send 'hg_bulk_t' over the wire. During encoding stage we
@@ -131,86 +163,81 @@ crt_proc_crt_bulk_t(crt_proc_t proc, crt_proc_op_t proc_op, crt_bulk_t *pcrt_bul
 	case CRT_PROC_ENCODE:
 		bulk = *pcrt_bulk;
 
-		/* RPC can have a NULL bulk. if so, encode a NULL value */
-		if (!bulk) {
-			tmp_hg_bulk = HG_BULK_NULL;
-			hg_ret      = hg_proc_hg_bulk_t(proc, (hg_bulk_t *)&tmp_hg_bulk);
-			return (hg_ret == HG_SUCCESS) ? 0 : -DER_HG;
-		}
-
 		/* Deferred allocation as a result of D_QUOTA_BULKS limit */
-		if (bulk->deferred) {
-			struct crt_context *ctx;
-			int                 rc;
-
-			/* Create mercury handle based on saved params */
-			ctx = bulk->crt_ctx;
-			D_ASSERT(ctx != NULL);
-
-			rc = crt_hg_bulk_create(&ctx->cc_hg_ctx, &bulk->sgl, bulk->bulk_perm,
-						&bulk->hg_bulk_hdl);
-			if (rc != DER_SUCCESS)
+		if (bulk != CRT_BULK_NULL) {
+			if (bulk->deferred && (rc = crt_proc_crt_bulk_t_deferred(bulk)) != 0) {
+				DL_ERROR(rc, "Failed to do deferred bulk allocation during proc");
 				return rc;
-
-			record_quota_resource(ctx, CRT_QUOTA_BULKS);
-
-			if (bulk->bound) {
-				rc = crt_hg_bulk_bind(bulk->hg_bulk_hdl, &ctx->cc_hg_ctx);
-				if (rc != 0) {
-					D_ERROR("Failed to bind bulk during proc\n");
-					/* free will return quota resource */
-					crt_bulk_free(bulk->hg_bulk_hdl);
-					return rc;
-				}
 			}
-			bulk->deferred = false;
+			hg_bulk = bulk->hg_bulk_hdl;
+		} else {
+			/* RPC can have a NULL bulk. if so, encode a NULL value */
+			hg_bulk = HG_BULK_NULL;
 		}
 
 		/* Pack mercury bulk handle to send over the wire */
-		hg_ret = hg_proc_hg_bulk_t(proc, (hg_bulk_t *)&bulk->hg_bulk_hdl);
+		hg_ret = hg_proc_hg_bulk_t(proc, &hg_bulk);
 		return (hg_ret == HG_SUCCESS) ? 0 : -DER_HG;
-		break;
 
 	case CRT_PROC_DECODE:
 		/* unpack mercury handle and wrap it around crt_bulk_t struct */
-		hg_ret = hg_proc_hg_bulk_t(proc, &tmp_hg_bulk);
+		hg_ret = hg_proc_hg_bulk_t(proc, &hg_bulk);
 		if (hg_ret != HG_SUCCESS)
 			return -DER_HG;
 
 		/* don't create a bulk wrapper if null bulk was transmitted */
-		if (tmp_hg_bulk == HG_BULK_NULL) {
+		if (hg_bulk == HG_BULK_NULL) {
 			*pcrt_bulk = NULL;
 			return 0;
 		}
 
 		/* Allocate space for a wrapper struct */
 		D_ALLOC_PTR(bulk);
-		if (!bulk)
+		if (bulk == NULL)
 			return -DER_NOMEM;
 
-		bulk->hg_bulk_hdl = tmp_hg_bulk;
+		bulk->hg_bulk_hdl = hg_bulk;
+		bulk->refcount    = 1;
 		bulk->deferred    = false;
+		bulk->bound       = false;
 		bulk->crt_ctx     = NULL;
+		bulk->iovs        = NULL;
 
 		*pcrt_bulk = bulk;
 		return 0;
-		break;
 
 	case CRT_PROC_FREE:
 		bulk = *pcrt_bulk;
 
 		if (bulk == NULL)
 			return 0;
 
-		hg_ret = hg_proc_hg_bulk_t(proc, &bulk->hg_bulk_hdl);
+		/**
+		 * Prevent HG proc from assigning NULL if refcount is not zero and keep reference on
+		 * HG bulk, we'll free it ourselves. hg_proc_hg_bulk_t() will decrement refcount on
+		 * the HG bulk.
+		 */
+		hg_bulk = bulk->hg_bulk_hdl;
+		HG_Bulk_ref_incr(hg_bulk);
+		hg_ret = hg_proc_hg_bulk_t(proc, &hg_bulk);
+		if (hg_ret != HG_SUCCESS) {
+			D_ERROR("Failed to free bulk during proc (%s)\n",
+				HG_Error_to_string(hg_ret));
+			/* Decrement the refcount we just incremented since proc failed */
+			hg_ret = HG_Bulk_free(hg_bulk);
+			if (hg_ret != HG_SUCCESS)
+				D_ERROR("HG_Bulk_free() failed during error cleanup (%s)\n",
+					HG_Error_to_string(hg_ret));
+			return -DER_HG;
+		}
+
+		if (atomic_fetch_sub(&bulk->refcount, 1) > 1)
+			return 0;
 
-		/* Free the wrapper struct */
-		if (bulk->iovs)
-			D_FREE(bulk->iovs);
-		D_FREE(bulk);
+		/* This is the real free */
+		crt_bulk_free_common(bulk);
 		*pcrt_bulk = NULL;
-		return (hg_ret == HG_SUCCESS) ? 0 : -DER_HG;
-		break;
+		return 0;
 	}
 
 	/* Should not get here */

src/cart/crt_internal_fns.h

@@ -1,6 +1,6 @@
 /*
  * (C) Copyright 2016-2024 Intel Corporation.
- * (C) Copyright 2025 Hewlett Packard Enterprise Development LP
+ * (C) Copyright 2025-2026 Hewlett Packard Enterprise Development LP
  *
  * SPDX-License-Identifier: BSD-2-Clause-Patent
  */
@@ -62,6 +62,9 @@ crt_bulk_desc_dup(struct crt_bulk_desc *bulk_desc_new,
 	*bulk_desc_new = *bulk_desc;
 }
 
+void
+crt_bulk_free_common(struct crt_bulk *bulk);
+
 void
 crt_hdlr_proto_query(crt_rpc_t *rpc_req);
 

src/cart/crt_internal_types.h

@@ -429,6 +429,7 @@ struct crt_bulk {
 	d_iov_t        *iovs;        /** original iovs */
 	d_sg_list_t     sgl;         /** original sgl */
 	crt_bulk_perm_t bulk_perm;   /** bulk permissions */
+	ATOMIC uint32_t refcount;    /** reference count for this struct */
 };
 
 /* crt_context */