Revert "block: bio_copy_data_iter"

This reverts commit db1c7d77.

We're reinstating the pktcdvd driver, which needs this API.
Signed-off-by: Jens Axboe <axboe@kernel.dk>

block/bio.c

@@ -1401,6 +1401,27 @@ void __bio_advance(struct bio *bio, unsigned bytes)
 }
 EXPORT_SYMBOL(__bio_advance);
 
+void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
+			struct bio *src, struct bvec_iter *src_iter)
+{
+	while (src_iter->bi_size && dst_iter->bi_size) {
+		struct bio_vec src_bv = bio_iter_iovec(src, *src_iter);
+		struct bio_vec dst_bv = bio_iter_iovec(dst, *dst_iter);
+		unsigned int bytes = min(src_bv.bv_len, dst_bv.bv_len);
+		void *src_buf = bvec_kmap_local(&src_bv);
+		void *dst_buf = bvec_kmap_local(&dst_bv);
+
+		memcpy(dst_buf, src_buf, bytes);
+
+		kunmap_local(dst_buf);
+		kunmap_local(src_buf);
+
+		bio_advance_iter_single(src, src_iter, bytes);
+		bio_advance_iter_single(dst, dst_iter, bytes);
+	}
+}
+EXPORT_SYMBOL(bio_copy_data_iter);
+
 /**
  * bio_copy_data - copy contents of data buffers from one bio to another
  * @src: source bio
@@ -1414,21 +1435,7 @@ void bio_copy_data(struct bio *dst, struct bio *src)
 	struct bvec_iter src_iter = src->bi_iter;
 	struct bvec_iter dst_iter = dst->bi_iter;
 
-	while (src_iter.bi_size && dst_iter.bi_size) {
-		struct bio_vec src_bv = bio_iter_iovec(src, src_iter);
-		struct bio_vec dst_bv = bio_iter_iovec(dst, dst_iter);
-		unsigned int bytes = min(src_bv.bv_len, dst_bv.bv_len);
-		void *src_buf = bvec_kmap_local(&src_bv);
-		void *dst_buf = bvec_kmap_local(&dst_bv);
-
-		memcpy(dst_buf, src_buf, bytes);
-
-		kunmap_local(dst_buf);
-		kunmap_local(src_buf);
-
-		bio_advance_iter_single(src, &src_iter, bytes);
-		bio_advance_iter_single(dst, &dst_iter, bytes);
-	}
+	bio_copy_data_iter(dst, &dst_iter, src, &src_iter);
 }
 EXPORT_SYMBOL(bio_copy_data);
 

include/linux/bio.h

@@ -475,6 +475,8 @@ void __bio_release_pages(struct bio *bio, bool mark_dirty);
 extern void bio_set_pages_dirty(struct bio *bio);
 extern void bio_check_pages_dirty(struct bio *bio);
 
+extern void bio_copy_data_iter(struct bio *dst, struct bvec_iter *dst_iter,
+			       struct bio *src, struct bvec_iter *src_iter);
 extern void bio_copy_data(struct bio *dst, struct bio *src);
 extern void bio_free_pages(struct bio *bio);
 void guard_bio_eod(struct bio *bio);