dm cache: return -EINVAL if the user specifies unknown cache policy

Return -EINVAL when the specified cache policy is unknown rather than
returning -ENOMEM.
Signed-off-by: Mikulas Patocka <mpatocka@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>

drivers/md/dm-cache-policy.c

@@ -119,13 +119,13 @@ struct dm_cache_policy *dm_cache_policy_create(const char *name,
 	type = get_policy(name);
 	if (!type) {
 		DMWARN("unknown policy type");
-		return NULL;
+		return ERR_PTR(-EINVAL);
 	}
 
 	p = type->create(cache_size, origin_size, cache_block_size);
 	if (!p) {
 		put_policy(type);
-		return NULL;
+		return ERR_PTR(-ENOMEM);
 	}
 	p->private = type;
 

drivers/md/dm-cache-target.c

@@ -1879,14 +1879,15 @@ static int set_config_values(struct cache *cache, int argc, const char **argv)
 static int create_cache_policy(struct cache *cache, struct cache_args *ca,
 			       char **error)
 {
-	cache->policy =	dm_cache_policy_create(ca->policy_name,
-					       cache->cache_size,
-					       cache->origin_sectors,
-					       cache->sectors_per_block);
-	if (!cache->policy) {
+	struct dm_cache_policy *p = dm_cache_policy_create(ca->policy_name,
+							   cache->cache_size,
+							   cache->origin_sectors,
+							   cache->sectors_per_block);
+	if (IS_ERR(p)) {
 		*error = "Error creating cache's policy";
-		return -ENOMEM;
+		return PTR_ERR(p);
 	}
+	cache->policy = p;
 
 	return 0;
 }