size_t csum_and_copy_to_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
size_t csum_and_copy_from_iter(void *addr, size_t bytes, __wsum *csum, struct iov_iter *i);
-int memcpy_fromiovec(unsigned char *kdata, struct iovec *iov, int len);
int memcpy_fromiovecend(unsigned char *kdata, const struct iovec *iov,
int offset, int len);
int memcpy_toiovecend(const struct iovec *v, unsigned char *kdata,