CORTX-33537: allow degraded i/o for the new objects

Currently, if no clean pool version (actual or formulaic)
can be found for the new object on its creation, -ENOENT is
returned, which is not good. We want the user to be able to
create new objects even if this implies the degraded i/o on
them.

Solution: return the actual pver at conf_pver_find_locked()
in case when nothing better (cleaner) can be found.

Closes Seagate#1958.
Relates Seagate/cortx-hare#2123.

Signed-off-by: Andriy Tkachuk <andriy.tkachuk@seagate.com>

conf/pvers.c

@@ -137,6 +137,7 @@ static int conf_pver_find_locked(const struct m0_conf_pool *pool,
 	if (rc != 0)
 		return M0_ERR_INFO(rc, "Recd update failed for pool "FID_F,
 			   FID_P(&pool->pl_obj.co_id));
+	*out = NULL;
 	m0_tl_for (m0_conf_dir, &pool->pl_pvers->cd_items, obj) {
 		pver = M0_CONF_CAST(obj, m0_conf_pver);
 		M0_LOG(M0_DEBUG, "pver="FID_F, FID_P(&pver->pv_obj.co_id));
@@ -145,14 +146,22 @@ static int conf_pver_find_locked(const struct m0_conf_pool *pool,
 			M0_LOG(M0_INFO, "Skipping "FID_F, FID_P(pver_to_skip));
 			continue;
 		}
+		if (pver->pv_kind == M0_CONF_PVER_ACTUAL)
+			*out = pver; /* cache it for now */
 		if (!m0_conf_pver_is_clean(pver))
 			continue;
-		if (pver->pv_kind == M0_CONF_PVER_ACTUAL) {
-			*out = pver;
+		if (pver->pv_kind == M0_CONF_PVER_ACTUAL)
 			return M0_RC(0);
-		}
 		return M0_RC(conf_pver_formulate(pver, out));
 	} m0_tl_endfor;
+
+	/*
+	 * Return the actual pver if we cannot find anything better.
+	 * The I/O will be performed in the degraded mode.
+	 */
+	if (*out != NULL)
+		return M0_RC(0);
+
 	return M0_ERR_INFO(-ENOENT, "No suitable pver is found at pool "FID_F,
 			   FID_P(&pool->pl_obj.co_id));
 }

conf/ut/pvers.c

@@ -112,7 +112,8 @@ static void test_pver_find(void)
 
 	conf_ut_ha_state_set(cache, &failed[0], M0_NC_FAILED);
 	rc = m0_conf_pver_find(pool, NULL, &pver);
-	M0_UT_ASSERT(rc == -ENOENT);
+	M0_UT_ASSERT(rc == 0);
+	M0_UT_ASSERT(pver->pv_kind == M0_CONF_PVER_ACTUAL);
 	for (i = 1; i < ARRAY_SIZE(failed); ++i)
 		conf_ut_ha_state_set(cache, &failed[i], M0_NC_FAILED);
 	rc = m0_conf_pver_find(pool, NULL, &pver_virt);