
consider this situation: no more fresh block, meantime an item with such a big size come in, and currently no block inuse has sufficient space to save this item, the code will run into the modified line, and KV_MGR_WORKSPACE will be set to KV_BLK_INVALID. this will cause no matter what size of an item wanna come in again, kv_blk_search_suitable just return KV_BLK_INVALID because "if (KV_MGR_WORKSPACE == KV_BLK_INVALID)" is true.