Commit 5c67aa90 authored by Al Viro's avatar Al Viro
Browse files

iov_iter: unify iterate_iovec and iterate_kvec 



The differences between iterate_iovec and iterate_kvec are minor:
	* kvec callback is treated as if it returned 0
	* initialization of __p is with i->iov and i->kvec resp.
which is trivially dealt with.

No code generation changes - compiler is quite capable of turning
	left = ((void)(STEP), 0);
	__v.iov_len -= left;
(with no accesses to left downstream) and
	(void)(STEP);
into the same code.

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 7a1bcb5d

lib/iov_iter.c

+5 −23
Original line number Diff line number Diff line
@@ -16,10 +16,10 @@ 


#define PIPE_PARANOIA /* for now */



/* covers iovec and kvec alike */

#define iterate_iovec(i, n, __v, __p, skip, STEP) {		\

	size_t left;						\

	size_t wanted = n;					\

	__p = i->iov;						\

	do {							\

		__v.iov_len = min(n, __p->iov_len - skip);	\

		if (likely(__v.iov_len)) {			\
@@ -37,25 +37,6 @@ 
	n = wanted - n;						\

}



#define iterate_kvec(i, n, __v, __p, skip, STEP) {		\

	size_t wanted = n;					\

	__p = i->kvec;						\

	do {							\

		__v.iov_len = min(n, __p->iov_len - skip);	\

		if (likely(__v.iov_len)) {			\

			__v.iov_base = __p->iov_base + skip;	\

			(void)(STEP);				\

			skip += __v.iov_len;			\

			n -= __v.iov_len;			\

			if (skip < __p->iov_len)		\

				break;				\

		}						\

		__p++;						\

		skip = 0;					\

	} while (n);						\

	n = wanted - n;						\

}



#define iterate_bvec(i, n, __v, __bi, skip, STEP) {	\

	struct bvec_iter __start;			\

	__start.bi_size = n;				\
@@ -109,7 +90,7 @@ 
	if (likely(n)) {					\

		size_t skip = i->iov_offset;			\

		if (likely(iter_is_iovec(i))) {			\

			const struct iovec *iov;		\

			const struct iovec *iov = i->iov;	\

			struct iovec v;				\

			iterate_iovec(i, n, v, iov, skip, (I))	\

			i->nr_segs -= iov - i->iov;		\
@@ -123,9 +104,10 @@ 
			i->nr_segs -= i->bvec - bvec;		\

			skip = __bi.bi_bvec_done;		\

		} else if (iov_iter_is_kvec(i)) {		\

			const struct kvec *kvec;		\

			const struct kvec *kvec = i->kvec;	\

			struct kvec v;				\

			iterate_kvec(i, n, v, kvec, skip, (K))	\

			iterate_iovec(i, n, v, kvec, skip,	\

						((void)(K),0))	\

			i->nr_segs -= kvec - i->kvec;		\

			i->kvec = kvec;				\

		} else if (iov_iter_is_xarray(i)) {		\