new helper: iov_iter_bvec()

similar to iov_iter_kvec(), for ITER_BVEC ones

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

2 files changed, 17 insertions, 9 deletions

diff --git a/mm/iov_iter.c b/mm/iov_iter.c
index a1599ca4ab0e..827732047da1 100644
--- a/mm/iov_iter.c
+++ b/mm/iov_iter.c
@@ -501,18 +501,31 @@ size_t iov_iter_single_seg_count(const struct iov_iter *i)
 EXPORT_SYMBOL(iov_iter_single_seg_count);
 
 void iov_iter_kvec(struct iov_iter *i, int direction,
-			const struct kvec *iov, unsigned long nr_segs,
+			const struct kvec *kvec, unsigned long nr_segs,
 			size_t count)
 {
 	BUG_ON(!(direction & ITER_KVEC));
 	i->type = direction;
-	i->kvec = (struct kvec *)iov;
+	i->kvec = kvec;
 	i->nr_segs = nr_segs;
 	i->iov_offset = 0;
 	i->count = count;
 }
 EXPORT_SYMBOL(iov_iter_kvec);
 
+void iov_iter_bvec(struct iov_iter *i, int direction,
+			const struct bio_vec *bvec, unsigned long nr_segs,
+			size_t count)
+{
+	BUG_ON(!(direction & ITER_BVEC));
+	i->type = direction;
+	i->bvec = bvec;
+	i->nr_segs = nr_segs;
+	i->iov_offset = 0;
+	i->count = count;
+}
+EXPORT_SYMBOL(iov_iter_bvec);
+
 unsigned long iov_iter_alignment(const struct iov_iter *i)
 {
 	unsigned long res = 0;
diff --git a/mm/page_io.c b/mm/page_io.c
index 955db8b0d497..e6045804c8d8 100644
--- a/mm/page_io.c
+++ b/mm/page_io.c
@@ -269,14 +269,9 @@ int __swap_writepage(struct page *page, struct writeback_control *wbc,
 			.bv_len  = PAGE_SIZE,
 			.bv_offset = 0
 		};
-		struct iov_iter from = {
-			.type = ITER_BVEC | WRITE,
-			.count = PAGE_SIZE,
-			.iov_offset = 0,
-			.nr_segs = 1,
-		};
-		from.bvec = &bv;	/* older gcc versions are broken */
+		struct iov_iter from;
 
+		iov_iter_bvec(&from, ITER_BVEC | WRITE, &bv, 1, PAGE_SIZE);
 		init_sync_kiocb(&kiocb, swap_file);
 		kiocb.ki_pos = page_file_offset(page);
 		kiocb.ki_nbytes = PAGE_SIZE;