1. A method for use in managing global metadata caches in data storage systems, the method comprising: allocating space in a memory of a data storage system to a global metadata cache, configured to store metadata objects for a plurality of different file systems responsive to file system access requests from the plurality of different file systems, wherein each file system of the plurality of different file systems is associated with a local file system cache, wherein metadata information of a file system cached in a local file system cache associated with the file system refers to metadata cached in the global metadata cache; associating a global reusable list with the global metadata cache; and storing a metadata object associated with a file of a file system of the plurality of different file systems in the global metadata cache by using a metadata object of the global reusable list, wherein the metadata object is accessed by a plurality of different versions of the file.