Amazon S3 File Gateway now enables you to force-close locked files on SMB file shares on Amazon S3 File Gateway by providing access to local security groups. Amazon S3 File Gateway provides on-premises applications with file-based, cached access to virtually unlimited cloud storage using SMB and NFS protocols. End users and applications using files on SMB shares, may stop working on those files without closing them. This leaves the files in an open, or locked, state. Until now, gateway administrators did not have permissions to close these files.
Source:: Amazon AWS