Commit 7ce2a91e authored by Al Viro's avatar Al Viro
Browse files

iov_iter.c: iterate_and_advance 



same as iterate_all_kinds, but iterator is moved to the position past
the last byte we'd handled.

iov_iter_advance() converted to it

Signed-off-by: default avatarAl Viro <viro@zeniv.linux.org.uk>
parent 04a31165

mm/iov_iter.c

+28 −76
Original line number Diff line number Diff line
@@ -70,6 +70,33 @@ 
	}							\

}



#define iterate_and_advance(i, n, v, I, B) {			\

	size_t skip = i->iov_offset;				\

	if (unlikely(i->type & ITER_BVEC)) {			\

		const struct bio_vec *bvec;			\

		struct bio_vec v;				\

		iterate_bvec(i, n, v, bvec, skip, (B))		\

		if (skip == bvec->bv_len) {			\

			bvec++;					\

			skip = 0;				\

		}						\

		i->nr_segs -= bvec - i->bvec;			\

		i->bvec = bvec;					\

	} else {						\

		const struct iovec *iov;			\

		struct iovec v;					\

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

		if (skip == iov->iov_len) {			\

			iov++;					\

			skip = 0;				\

		}						\

		i->nr_segs -= iov - i->iov;			\

		i->iov = iov;					\

	}							\

	i->count -= n;						\

	i->iov_offset = skip;					\

}



static size_t copy_to_iter_iovec(void *from, size_t bytes, struct iov_iter *i)

{

	size_t skip, copy, left, wanted;
@@ -366,42 +393,6 @@ static size_t zero_iovec(size_t bytes, struct iov_iter *i) 
	return wanted - bytes;

}



static void advance_iovec(struct iov_iter *i, size_t bytes)

{

	BUG_ON(i->count < bytes);



	if (likely(i->nr_segs == 1)) {

		i->iov_offset += bytes;

		i->count -= bytes;

	} else {

		const struct iovec *iov = i->iov;

		size_t base = i->iov_offset;

		unsigned long nr_segs = i->nr_segs;



		/*

		 * The !iov->iov_len check ensures we skip over unlikely

		 * zero-length segments (without overruning the iovec).

		 */

		while (bytes || unlikely(i->count && !iov->iov_len)) {

			int copy;



			copy = min(bytes, iov->iov_len - base);

			BUG_ON(!i->count || i->count < copy);

			i->count -= copy;

			bytes -= copy;

			base += copy;

			if (iov->iov_len == base) {

				iov++;

				nr_segs--;

				base = 0;

			}

		}

		i->iov = iov;

		i->iov_offset = base;

		i->nr_segs = nr_segs;

	}

}



/*

 * Fault in the first iovec of the given iov_iter, to a maximum length

 * of bytes. Returns 0 on success, or non-zero if the memory could not be
@@ -685,42 +676,6 @@ static size_t zero_bvec(size_t bytes, struct iov_iter *i) 
	return wanted - bytes;

}



static void advance_bvec(struct iov_iter *i, size_t bytes)

{

	BUG_ON(i->count < bytes);



	if (likely(i->nr_segs == 1)) {

		i->iov_offset += bytes;

		i->count -= bytes;

	} else {

		const struct bio_vec *bvec = i->bvec;

		size_t base = i->iov_offset;

		unsigned long nr_segs = i->nr_segs;



		/*

		 * The !iov->iov_len check ensures we skip over unlikely

		 * zero-length segments (without overruning the iovec).

		 */

		while (bytes || unlikely(i->count && !bvec->bv_len)) {

			int copy;



			copy = min(bytes, bvec->bv_len - base);

			BUG_ON(!i->count || i->count < copy);

			i->count -= copy;

			bytes -= copy;

			base += copy;

			if (bvec->bv_len == base) {

				bvec++;

				nr_segs--;

				base = 0;

			}

		}

		i->bvec = bvec;

		i->iov_offset = base;

		i->nr_segs = nr_segs;

	}

}



static ssize_t get_pages_bvec(struct iov_iter *i,

		   struct page **pages, size_t maxsize, unsigned maxpages,

		   size_t *start)
@@ -849,10 +804,7 @@ EXPORT_SYMBOL(iov_iter_copy_from_user_atomic); 


void iov_iter_advance(struct iov_iter *i, size_t size)

{

	if (i->type & ITER_BVEC)

		advance_bvec(i, size);

	else

		advance_iovec(i, size);

	iterate_and_advance(i, size, v, 0, 0)

}

EXPORT_SYMBOL(iov_iter_advance);