cache: filter out unsupported policy settings

Loading invalid MQ/SMQ policy settings table line cause immediate
rejection - to prevent such failure, automatically filter valid
settins before it is being uploaded by lvm2.

For invalid setting issue a warnning informing user how to remove
them.

This solution is used to keep running cached LVs that might had
been created in the past with invalid settings that have been actually
unused due to another code bug.

1 files changed, 59 insertions, 1 deletions

diff --git a/lib/cache_segtype/cache.c b/lib/cache_segtype/cache.c
index 69b46a55b..93d4c5283 100644
--- a/lib/cache_segtype/cache.c
+++ b/lib/cache_segtype/cache.c
@@ -618,6 +618,9 @@ static int _cache_add_target_line(struct dev_manager *dm,
 {
 	struct lv_segment *cache_pool_seg;
 	struct lv_segment *setting_seg;
+	struct dm_config_node *policy_settings;
+	struct dm_config_node *cn;
+	unsigned  i, j;
 	union lvid metadata_lvid;
 	union lvid data_lvid;
 	char *metadata_uuid, *data_uuid, *origin_uuid;
@@ -718,6 +721,61 @@ static int _cache_add_target_line(struct dev_manager *dm,
 			return_0;
 	}
 
+	policy_settings = seg->cleaner_policy ? NULL : setting_seg->policy_settings;
+	if (policy_settings && cache_pool_seg->policy_name) {
+		static const struct act {
+			const char *name;
+			const char *settings[20];
+		} _accepted[] = {
+			{
+				"MQ", {
+					"migration_threshold", "sequential_threshold", "random_threshold",
+					"read_promote_adjustment", "write_promote_adjustment",
+					"discard_promote_adjustment", NULL
+				},
+			}, {
+				"SMQ", {
+					"migration_threshold", NULL
+				}
+			}
+		};
+
+                /* Check if cache settings are acceptable to knownm policies */
+		for (i = 0; i < DM_ARRAY_SIZE(_accepted); i++) {
+			if (strcasecmp(cache_pool_seg->policy_name, _accepted[i].name))
+				continue;
+
+			for (cn = policy_settings->child; cn; cn = cn->sib) {
+				for (j = 0; _accepted[i].settings[j]; j++)
+					if (strcmp(cn->key, _accepted[i].settings[j]) == 0)
+						break; /* -> Valid setting */
+
+				/* Have we found 'unsupported' cache setting? */
+				if (!_accepted[i].settings[j]) {
+					/* Make a copy of policy settings a remove unsupported settings and Warn */
+					if (!(policy_settings = dm_config_clone_node_with_mem(mem, policy_settings, 0)))
+						return_0;
+				restart:
+					for (cn = policy_settings->child; cn; cn = cn->sib) {
+						for (j = 0; _accepted[i].settings[j]; j++) {
+							if (strcmp(cn->key, _accepted[i].settings[j]) == 0)
+								break; /* need to be dropped */
+						}
+						if (!_accepted[i].settings[j]) {
+							log_warn("WARNING: %s cache policy does not support \"%s=" FMTu64 "\" setting, "
+								 "remove with 'lvchange --cachesettings \"%s=default\" ...'.",
+								 _accepted[i].name, cn->key, cn->v->v.i, cn->key);
+							dm_config_remove_node(policy_settings, cn);
+							goto restart;
+						}
+					}
+					break;
+				}
+			}
+			break;
+		}
+	}
+
 	if (!dm_tree_node_add_cache_target(node, len,
 					   feature_flags,
 					   metadata_uuid,
@@ -726,7 +784,7 @@ static int _cache_add_target_line(struct dev_manager *dm,
 					   seg->cleaner_policy ? "cleaner" :
 						   /* undefined policy name -> likely an old "mq" */
 						   cache_pool_seg->policy_name ? : "mq",
-					   seg->cleaner_policy ? NULL : setting_seg->policy_settings,
+					   policy_settings,
 					   seg->metadata_start,
 					   seg->metadata_len,
 					   seg->data_start,