AgInodeBits
uint32 agRelativeInodeNo = INO_TO_AGINO(fId, fVolume->AgInodeBits());
#define INO_TO_AGNO(id, volume) ((xfs_agnumber_t)id >> (volume->AgInodeBits()))
uint8 AgInodeBits() const
{ return fSuperBlock.AgInodeBits(); }
uint8 AgInodeBits() const;