c - Get cluster size

Question

I am working on an upper volume filter driver taking diskperf as base.
I want to know how can I calculate cluster size(allocation unit size).
I know that using GetDiskFreeSpace I can get the desired output, but it's useful only in user mode.
I want it to work at the kernel level.
Is there any IOCTL or any function that will help me to find the cluster size?

Answer 1

ZwQueryVolumeInformationFile/NtQueryVolumeInformationFileFsInformationClass 设置为FILE_FS_SIZE_INFORMATIONstruct。

或使用IRP_MJ_QUERY_VOLUME_INFORMATION。