csum_fn            12 block/t10-pi.c typedef __be16 (csum_fn) (void *, unsigned int);
csum_fn            30 block/t10-pi.c 		csum_fn *fn, enum t10_dif_type type)
csum_fn            54 block/t10-pi.c 		csum_fn *fn, enum t10_dif_type type)