ceph: update readpages osd request according to size of pages

add_to_page_cache_lru() can fails, so the actual pages to read
can be smaller than the initial size of osd request. We need to
update osd request size in that case.
Signed-off-by: NYan, Zheng <zyan@redhat.com>
Reviewed-by: NJeff Layton <jlayton@redhat.com>

fs/ceph/addr.c

@@ -391,6 +391,7 @@ static int start_read(struct inode *inode, struct list_head *page_list, int max)
 			nr_pages = i;
 			if (nr_pages > 0) {
 				len = nr_pages << PAGE_SHIFT;
+				osd_req_op_extent_update(req, 0, len);
 				break;
 			}
 			goto out_pages;

net/ceph/osd_client.c

@@ -672,7 +672,8 @@ void osd_req_op_extent_update(struct ceph_osd_request *osd_req,
 	BUG_ON(length > previous);
 
 	op->extent.length = length;
-	op->indata_len -= previous - length;
+	if (op->op == CEPH_OSD_OP_WRITE || op->op == CEPH_OSD_OP_WRITEFULL)
+		op->indata_len -= previous - length;
 }
 EXPORT_SYMBOL(osd_req_op_extent_update);