md: more open-coded offset_in_page()

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/drivers/md/bcache/util.c b/drivers/md/bcache/util.c
index db3ae4c..dde6172 100644
--- a/drivers/md/bcache/util.c
+++ b/drivers/md/bcache/util.c
@@ -230,7 +230,7 @@
 	BUG_ON(!bio->bi_iter.bi_size);
 	BUG_ON(bio->bi_vcnt);
 
-	bv->bv_offset = base ? ((unsigned long) base) % PAGE_SIZE : 0;
+	bv->bv_offset = base ? offset_in_page(base) : 0;
 	goto start;
 
 	for (; size; bio->bi_vcnt++, bv++) {
diff --git a/drivers/md/dm-io.c b/drivers/md/dm-io.c
index 81c5e1a..06d426e 100644
--- a/drivers/md/dm-io.c
+++ b/drivers/md/dm-io.c
@@ -246,7 +246,7 @@
 {
 	dp->get_page = vm_get_page;
 	dp->next_page = vm_next_page;
-	dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
+	dp->context_u = offset_in_page(data);
 	dp->context_ptr = data;
 }
 
@@ -271,7 +271,7 @@
 {
 	dp->get_page = km_get_page;
 	dp->next_page = km_next_page;
-	dp->context_u = ((unsigned long) data) & (PAGE_SIZE - 1);
+	dp->context_u = offset_in_page(data);
 	dp->context_ptr = data;
 }