He was rummaging through the suitcase for his passport, making a mess of all the clothes.

rummaging 是动词 rummage 的现在分词形式。rummage 的意思是"翻找、乱翻"，通常指在杂乱的地方急切地寻找某物。这个词带有"翻得乱七八糟"的负面含义。