DAOS-18604 dfs: EC should not be used for directories (#17573)

- if dir-oclass is set to EC on container create, use default instead.
- daos fs set-attr of an EC oclass on directory should apply only to
  files. directories will be create with the default in that case.
- fix daos fs get-attr to show such changes

Signed-off-by: Mohamad Chaarawi <mohamad.chaarawi@hpe.com>

Author: mchaarawi

src/client/dfs/README.md

@@ -134,7 +134,14 @@ Object testdir
 By default, all directories are created with an object class with 1 shard. This means, that if the
 container redundancy factor (RF) is 0, OC_S1 oclass will be used; if RF=1 OC_RP_2G1 is used, and so
 on. The user can of course change that when creating the directory and set the desired object class
-manually, or set the default object class when creating the container.
+manually, or set the default object class when creating the container. Using an EC object class
+class for directories is not recommended since directory entries are small and EC overhead will be
+large anyway. Thus when setting the directory object class on container creation to an EC object
+class, DAOS will ignore the user setting and use the default replication object class depending on
+the redundancy factory of the container as explained earlier. If one uses the DAOS tool to change
+the object class of new files and directories to be created under an existing directory (daos fs
+set-attr), and that object class is EC, that setting will apply only to files. New directories will
+use the container default in that case.
 
 Note that with this mapping, the inode information is stored with the entry that it corresponds to
 in the parent directory object. Thus, hard links won't be supported, since it won't be possible to

src/client/dfs/common.c

@@ -1,5 +1,6 @@
 /**
  * (C) Copyright 2018-2024 Intel Corporation.
+ * (C) Copyright 2026 Hewlett Packard Enterprise Development LP
  *
  * SPDX-License-Identifier: BSD-2-Clause-Patent
  */
@@ -643,8 +644,15 @@ create_dir(dfs_t *dfs, dfs_obj_t *parent, daos_oclass_id_t cid, dfs_obj_t *dir)
 	if (cid == 0) {
 		if (parent->d.oclass == 0)
 			cid = dfs->attr.da_dir_oclass_id;
-		else
+		else {
 			cid = parent->d.oclass;
+			/*
+			 * If the parent oclass is EC, do not use that for a directory and use the
+			 * container default instead.
+			 */
+			if (daos_cid_is_ec(cid))
+				cid = dfs->attr.da_dir_oclass_id;
+		}
 	}
 
 	/** Allocate an OID for the dir - local operation */

src/client/dfs/cont.c

@@ -1,6 +1,6 @@
 /**
  * (C) Copyright 2018-2024 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
  */
@@ -189,8 +189,14 @@ dfs_cont_create(daos_handle_t poh, uuid_t *cuuid, dfs_attr_t *attr, daos_handle_
 		}
 		if (attr->da_file_oclass_id)
 			dattr.da_file_oclass_id = attr->da_file_oclass_id;
-		if (attr->da_dir_oclass_id)
+		if (attr->da_dir_oclass_id) {
 			dattr.da_dir_oclass_id = attr->da_dir_oclass_id;
+			if (daos_cid_is_ec(dattr.da_dir_oclass_id)) {
+				D_WARN("EC object class for directories is not supported,"
+				       " reverting to use default");
+				dattr.da_dir_oclass_id = 0;
+			}
+		}
 
 		/** check non default mode */
 		if ((attr->da_mode & MODE_MASK) == DFS_RELAXED ||

src/client/dfs/obj.c

@@ -1,6 +1,6 @@
 /**
  * (C) Copyright 2018-2024 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
  */
@@ -81,7 +81,16 @@ dfs_obj_get_info(dfs_t *dfs, dfs_obj_t *obj, dfs_obj_info_t *info)
 
 		/** what is the default oclass files and dirs will be created with in this dir */
 		if (obj->d.oclass) {
-			info->doi_dir_oclass_id  = obj->d.oclass;
+			/** if parent oclass is EC, dir would be chosen as container default */
+			if (!daos_cid_is_ec(obj->d.oclass)) {
+				info->doi_dir_oclass_id = obj->d.oclass;
+			} else {
+				if (dfs->attr.da_dir_oclass_id)
+					info->doi_dir_oclass_id = dfs->attr.da_dir_oclass_id;
+				else
+					rc = daos_obj_get_oclass(dfs->coh, DAOS_OT_MULTI_HASHED, 0,
+								 0, &info->doi_dir_oclass_id);
+			}
 			info->doi_file_oclass_id = obj->d.oclass;
 		} else {
 			if (dfs->attr.da_dir_oclass_id)

src/include/daos/object.h

@@ -1,6 +1,6 @@
 /**
  * (C) Copyright 2016-2023 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
  */
@@ -404,6 +404,17 @@ daos_oclass_is_ec(struct daos_oclass_attr *oca)
 	return oca->ca_resil == DAOS_RES_EC;
 }
 
+static inline bool
+daos_cid_is_ec(daos_oclass_id_t cid)
+{
+	struct daos_oclass_attr *oca;
+
+	oca = daos_oclass_id2attr(cid, NULL);
+	if (oca == NULL)
+		return false;
+	return daos_oclass_is_ec(oca);
+}
+
 static inline void
 daos_obj_set_oid(daos_obj_id_t *oid, enum daos_otype_t type,
 		 enum daos_obj_redun ord, uint32_t nr_grps,

src/tests/suite/dfs_unit_test.c

@@ -1,6 +1,6 @@
 /**
  * (C) Copyright 2019-2024 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
  */
@@ -2256,11 +2256,12 @@ dfs_test_oclass_hints(void **state)
 	daos_oclass_id_t	cid;
 	daos_handle_t		coh;
 	dfs_t			*dfs_l;
-	dfs_obj_t		*obj;
+	dfs_obj_t               *obj, *dir;
 	daos_obj_id_t		oid;
 	daos_oclass_id_t	ecidx;
 	daos_prop_t             *prop = NULL;
 	dfs_attr_t		dattr = {0};
+	dfs_obj_info_t           oinfo = {0};
 	struct pl_map_attr      attr = {0};
 	int			rc;
 
@@ -2416,6 +2417,21 @@ dfs_test_oclass_hints(void **state)
 	rc = compare_oclass(coh, cid, OC_RP_2GX);
 	assert_rc_equal(rc, 0);
 
+	/** create a directory and set EC to be used on the directory */
+	rc = dfs_open(dfs_l, NULL, "d1", S_IFDIR | S_IWUSR | S_IRUSR, O_RDWR | O_CREAT, 0, 0, NULL,
+		      &dir);
+	assert_int_equal(rc, 0);
+	rc = dfs_obj_set_oclass(dfs_l, dir, 0, ecidx);
+	assert_int_equal(rc, 0);
+	/** get the dir info to query what oclass will be used */
+	rc = dfs_obj_get_info(dfs_l, dir, &oinfo);
+	assert_int_equal(rc, 0);
+	rc = compare_oclass(coh, oinfo.doi_dir_oclass_id, OC_RP_2G1);
+	assert_int_equal(rc, 0);
+	rc = compare_oclass(coh, oinfo.doi_file_oclass_id, ecidx);
+	assert_int_equal(rc, 0);
+	dfs_release(dir);
+
 	rc = dfs_umount(dfs_l);
 	assert_int_equal(rc, 0);
 	rc = daos_cont_close(coh, NULL);
@@ -2468,6 +2484,21 @@ dfs_test_oclass_hints(void **state)
 	rc = compare_oclass(coh, cid, OC_RP_3GX);
 	assert_rc_equal(rc, 0);
 
+	/** create a directory and set EC to be used on the directory */
+	rc = dfs_open(dfs_l, NULL, "d1", S_IFDIR | S_IWUSR | S_IRUSR, O_RDWR | O_CREAT, 0, 0, NULL,
+		      &dir);
+	assert_int_equal(rc, 0);
+	rc = dfs_obj_set_oclass(dfs_l, dir, 0, ecidx);
+	assert_int_equal(rc, 0);
+	/** get the dir info to query what oclass will be used */
+	rc = dfs_obj_get_info(dfs_l, dir, &oinfo);
+	assert_int_equal(rc, 0);
+	rc = compare_oclass(coh, oinfo.doi_dir_oclass_id, OC_RP_3G1);
+	assert_int_equal(rc, 0);
+	rc = compare_oclass(coh, oinfo.doi_file_oclass_id, ecidx);
+	assert_int_equal(rc, 0);
+	dfs_release(dir);
+
 	rc = dfs_umount(dfs_l);
 	assert_int_equal(rc, 0);
 	rc = daos_cont_close(coh, NULL);
@@ -2520,6 +2551,22 @@ dfs_test_oclass_hints(void **state)
 	rc = compare_oclass(coh, cid, OC_RP_4GX);
 	assert_rc_equal(rc, 0);
 
+	/** create a directory and set EC to be used on the directory */
+	rc = dfs_open(dfs_l, NULL, "d1", S_IFDIR | S_IWUSR | S_IRUSR, O_RDWR | O_CREAT, 0, 0, NULL,
+		      &dir);
+	assert_int_equal(rc, 0);
+	rc = dfs_obj_set_oclass(dfs_l, dir, 0, ecidx);
+	assert_int_equal(rc, 0);
+	/** get the dir info to query what oclass will be used */
+	rc = dfs_obj_get_info(dfs_l, dir, &oinfo);
+	assert_int_equal(rc, 0);
+	rc = compare_oclass(coh, oinfo.doi_dir_oclass_id, OC_RP_4G1);
+	assert_int_equal(rc, 0);
+	rc = compare_oclass(coh, oinfo.doi_file_oclass_id, ecidx);
+	assert_int_equal(rc, 0);
+	dfs_release(dir);
+
+	assert_int_equal(rc, 0);
 	rc = dfs_umount(dfs_l);
 	assert_int_equal(rc, 0);
 	rc = daos_cont_close(coh, NULL);