NTFS_MIN_LOG2_OF_CLUMP
#ifndef NTFS_MIN_LOG2_OF_CLUMP
#define NTFS_CLUMP_MIN (1 << (NTFS_MIN_LOG2_OF_CLUMP + 8))
clump = 1 << NTFS_MIN_LOG2_OF_CLUMP;
align_shift = NTFS_MIN_LOG2_OF_CLUMP;
align_shift = NTFS_MIN_LOG2_OF_CLUMP - 1 +
__ffs(size >> (8 + NTFS_MIN_LOG2_OF_CLUMP));