Fix error message for cache already in standby detach state

Signed-off-by: Piotr Debski <piotr.debski@intel.com>

casadm/extended_err_msg.c

@@ -282,6 +282,10 @@ struct {
 		"The cache contains dirty data assigned to the core. If you want to "
 		"continue, please use --force option.\nWarning: the data will be lost"
 	},
+	{
+		KCAS_ERR_STANDBY_DETACHED,
+		"Cache device is already in standby detached state."
+	},
 };
 
 const char *cas_strerr(int cas_error_code)

modules/cas_cache/layer_cache_management.c

@@ -2296,7 +2296,7 @@ int cache_mngt_standby_detach(struct kcas_standby_detach *cmd)
 
 	cache_priv = ocf_cache_get_priv(cache);
 	if (!cache_priv->cache_exp_obj_initialized) {
-		result = -KCAS_ERR_DETACHED;
+		result = -KCAS_ERR_STANDBY_DETACHED;
 		goto out_cache_put;
 	}
 

modules/include/cas_ioctl_codes.h

@@ -1,5 +1,5 @@
 /*
-* Copyright(c) 2012-2021 Intel Corporation
+* Copyright(c) 2012-2022 Intel Corporation
 * SPDX-License-Identifier: BSD-3-Clause
 */
 
@@ -557,6 +557,9 @@ enum kcas_error {
 	/** Removing core failed and rollback failed too */
 	KCAS_ERR_DETACHED,
 
+	/** Cache is already in standby detached state */
+	KCAS_ERR_STANDBY_DETACHED,
+
 	/** Cache has been stopped, but it may contain dirty data */
 	KCAS_ERR_STOPPED_DIRTY,