memset(UDF_SB_PARTMAPS(X)[(Y)].Z.s_bitmap, 0x00, size);\
UDF_SB_PARTMAPS(X)[(Y)].Z.s_bitmap->s_block_bitmap =\
(struct buffer_head **)(UDF_SB_PARTMAPS(X)[(Y)].Z.s_bitmap + 1);\
UDF_SB_PARTMAPS(X)[(Y)].Z.s_bitmap->s_nr_groups = nr_groups;\
memset(UDF_SB_PARTMAPS(X)[(Y)].Z.s_bitmap, 0x00, size);\
UDF_SB_PARTMAPS(X)[(Y)].Z.s_bitmap->s_block_bitmap =\
(struct buffer_head **)(UDF_SB_PARTMAPS(X)[(Y)].Z.s_bitmap + 1);\
UDF_SB_PARTMAPS(X)[(Y)].Z.s_bitmap->s_nr_groups = nr_groups;\