1 files changed, 13 insertions, 6 deletions

diff --git a/include/linux/page_ext.h b/include/linux/page_ext.h
index 76c817162d2f..af2b6216c8e0 100644
--- a/include/linux/page_ext.h
+++ b/include/linux/page_ext.h
@@ -119,14 +119,18 @@ struct page_ext_iter {
  * page_ext_iter_begin() - Prepare for iterating through page extensions.
  * @iter: page extension iterator.
  * @pfn: PFN of the page we're interested in.
+ * @count: maximum number of page extensions to return.
  *
  * Must be called with RCU read lock taken.
  *
  * Return: NULL if no page_ext exists for this page.
  */
 static inline struct page_ext *page_ext_iter_begin(struct page_ext_iter *iter,
-						unsigned long pfn)
+		unsigned long pfn, unsigned long count)
 {
+	if (!count)
+		return NULL;
+
 	iter->index = 0;
 	iter->start_pfn = pfn;
 	iter->page_ext = page_ext_lookup(pfn);
@@ -137,19 +141,22 @@ static inline struct page_ext *page_ext_iter_begin(struct page_ext_iter *iter,
 /**
  * page_ext_iter_next() - Get next page extension
  * @iter: page extension iterator.
+ * @count: maximum number of page extensions to return.
  *
  * Must be called with RCU read lock taken.
  *
  * Return: NULL if no next page_ext exists.
  */
-static inline struct page_ext *page_ext_iter_next(struct page_ext_iter *iter)
+static inline struct page_ext *page_ext_iter_next(struct page_ext_iter *iter,
+		unsigned long count)
 {
 	unsigned long pfn;
 
 	if (WARN_ON_ONCE(!iter->page_ext))
 		return NULL;
 
-	iter->index++;
+	if (++iter->index >= count)
+		return NULL;
 	pfn = iter->start_pfn + iter->index;
 
 	if (page_ext_iter_next_fast_possible(pfn))
@@ -182,9 +189,9 @@ static inline struct page_ext *page_ext_iter_get(const struct page_ext_iter *ite
  * IMPORTANT: must be called with RCU read lock taken.
  */
 #define for_each_page_ext(__page, __pgcount, __page_ext, __iter) \
-	for (__page_ext = page_ext_iter_begin(&__iter, page_to_pfn(__page));\
-		__page_ext && __iter.index < __pgcount;          \
-		__page_ext = page_ext_iter_next(&__iter))
+	for (__page_ext = page_ext_iter_begin(&__iter, page_to_pfn(__page), __pgcount); \
+		__page_ext; \
+		__page_ext = page_ext_iter_next(&__iter, __pgcount))
 
 #else /* !CONFIG_PAGE_EXTENSION */
 struct page_ext;