struct iov_iter_st

struct iov_iter_st {
	const giovec_t *iov;
	size_t iov_count; /* the number of iov */
	size_t iov_index; /* index of the current buffer */
	size_t iov_offset; /* byte offset in the current buffer */

	uint8_t block[MAX_CIPHER_BLOCK_SIZE]; /* incomplete block for reading */
	size_t block_size; /* actual block size of the cipher */
	size_t block_offset; /* offset in block */
};