SQL Server Disk I/O Latency by File

SELECT DB_NAME(vfs.database_id) AS db_name, mf.physical_name, mf.type_desc,
       vfs.num_of_reads, vfs.num_of_writes,
       CAST(vfs.io_stall_read_ms  / NULLIF(vfs.num_of_reads, 0)  AS DECIMAL(10,1)) AS avg_read_ms,
       CAST(vfs.io_stall_write_ms / NULLIF(vfs.num_of_writes, 0) AS DECIMAL(10,1)) AS avg_write_ms
FROM sys.dm_io_virtual_file_stats(NULL, NULL) vfs
JOIN sys.master_files mf ON mf.database_id = vfs.database_id AND mf.file_id = vfs.file_id
ORDER BY (vfs.io_stall_read_ms + vfs.io_stall_write_ms) DESC;