libceph: fix oops in ceph_msg_data_{pages,pagelist}_advance()

When there is no more data, ceph_msg_data_{pages,pagelist}_advance()
should not move on to the next page.

Signed-off-by: Yan, Zheng <zheng.z.yan@intel.com>
diff --git a/net/ceph/messenger.c b/net/ceph/messenger.c
index 30efc5c..4f55f9c 100644
--- a/net/ceph/messenger.c
+++ b/net/ceph/messenger.c
@@ -919,6 +919,9 @@
 	if (!bytes || cursor->page_offset)
 		return false;	/* more bytes to process in the current page */
 
+	if (!cursor->resid)
+		return false;   /* no more data */
+
 	/* Move on to the next page; offset is already at 0 */
 
 	BUG_ON(cursor->page_index >= cursor->page_count);
@@ -1004,6 +1007,9 @@
 	if (!bytes || cursor->offset & ~PAGE_MASK)
 		return false;	/* more bytes to process in the current page */
 
+	if (!cursor->resid)
+		return false;   /* no more data */
+
 	/* Move on to the next page */
 
 	BUG_ON(list_is_last(&cursor->page->lru, &pagelist->head));