SPACE_MAP_ROOT_SIZE   36 drivers/md/dm-cache-metadata.c #define SPACE_MAP_ROOT_SIZE 128
SPACE_MAP_ROOT_SIZE   24 drivers/md/dm-clone-metadata.h #define SPACE_MAP_ROOT_SIZE 128
SPACE_MAP_ROOT_SIZE  153 drivers/md/dm-era-target.c #define SPACE_MAP_ROOT_SIZE 128
SPACE_MAP_ROOT_SIZE   93 drivers/md/dm-thin-metadata.c #define SPACE_MAP_ROOT_SIZE 128