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>

net/ceph/messenger.c

@@ -919,6 +919,9 @@ static bool ceph_msg_data_pages_advance(struct ceph_msg_data_cursor *cursor,
 	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 @@ static bool ceph_msg_data_pagelist_advance(struct ceph_msg_data_cursor *cursor,
 	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));