mm/block: convert rw_page users to bio op use

The rw_page users were not converted to use bio/req ops. As a result
bdev_write_page is not passing down REQ_OP_WRITE and the IOs will
be sent down as reads.

Signed-off-by: Mike Christie <mchristi@redhat.com>
Fixes: 4e1b2d52a80d ("block, fs, drivers: remove REQ_OP compat defs and related code")

Modified by me to:

1) Drop op_flags passing into ->rw_page(), as we don't use it.
2) Make op_is_write() and friends safe to use for !CONFIG_BLOCK

Signed-off-by: Jens Axboe <axboe@fb.com>
diff --git a/mm/filemap.c b/mm/filemap.c
index 3083ded..daef091 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -887,9 +887,9 @@
  * After completing I/O on a page, call this routine to update the page
  * flags appropriately
  */
-void page_endio(struct page *page, int rw, int err)
+void page_endio(struct page *page, int op, int err)
 {
-	if (rw == READ) {
+	if (!op_is_write(op)) {
 		if (!err) {
 			SetPageUptodate(page);
 		} else {
@@ -897,7 +897,7 @@
 			SetPageError(page);
 		}
 		unlock_page(page);
-	} else { /* rw == WRITE */
+	} else {
 		if (err) {
 			SetPageError(page);
 			if (page->mapping)