md: raid1: use bio helper in process_checks()

Avoid to direct access to bvec table.

Signed-off-by: Ming Lei <tom.leiming@gmail.com>
Signed-off-by: Shaohua Li <shli@fb.com>

drivers/md/raid1.c

@@ -2111,6 +2111,7 @@ static void process_checks(struct r1bio *r1_bio)
 		int j;
 		int size;
 		int error;
+		struct bio_vec *bi;
 		struct bio *b = r1_bio->bios[i];
 		struct resync_pages *rp = get_resync_pages(b);
 		if (b->bi_end_io != end_sync_read)
@@ -2129,9 +2130,7 @@ static void process_checks(struct r1bio *r1_bio)
 		b->bi_private = rp;
 
 		size = b->bi_iter.bi_size;
-		for (j = 0; j < vcnt ; j++) {
-			struct bio_vec *bi;
-			bi = &b->bi_io_vec[j];
+		bio_for_each_segment_all(bi, b, j) {
 			bi->bv_offset = 0;
 			if (size > PAGE_SIZE)
 				bi->bv_len = PAGE_SIZE;
@@ -2155,17 +2154,22 @@ static void process_checks(struct r1bio *r1_bio)
 		int error = sbio->bi_error;
 		struct page **ppages = get_resync_pages(pbio)->pages;
 		struct page **spages = get_resync_pages(sbio)->pages;
+		struct bio_vec *bi;
+		int page_len[RESYNC_PAGES];
 
 		if (sbio->bi_end_io != end_sync_read)
 			continue;
 		/* Now we can 'fixup' the error value */
 		sbio->bi_error = 0;
 
+		bio_for_each_segment_all(bi, sbio, j)
+			page_len[j] = bi->bv_len;
+
 		if (!error) {
 			for (j = vcnt; j-- ; ) {
 				if (memcmp(page_address(ppages[j]),
 					   page_address(spages[j]),
-					   sbio->bi_io_vec[j].bv_len))
+					   page_len[j]))
 					break;
 			}
 		} else