File-system device allocation.

typedef struct _FSALLOCATE {
  ULONG      idFileSystem;  /*  File system identification. */
  ULONG      cSectorUnit;   /*  Number of sectors per allocation unit. */
  ULONG      cUnit;         /*  Number of allocation units. */
  ULONG      cUnitAvail;    /*  Number of allocation units available. */
  USHORT     cbSector;      /*  Number of bytes per sector. */
} FSALLOCATE;

typedef   FSALLOCATE   * PFSALLOCATE ;