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-rw-r--r--mm/gup.c26
1 files changed, 26 insertions, 0 deletions
diff --git a/mm/gup.c b/mm/gup.c
index ef7d2da9f03f..5856f68467b3 100644
--- a/mm/gup.c
+++ b/mm/gup.c
@@ -213,6 +213,32 @@ void unpin_user_page(struct page *page)
}
EXPORT_SYMBOL(unpin_user_page);
+static inline void compound_next(unsigned long i, unsigned long npages,
+ struct page **list, struct page **head,
+ unsigned int *ntails)
+{
+ struct page *page;
+ unsigned int nr;
+
+ if (i >= npages)
+ return;
+
+ page = compound_head(list[i]);
+ for (nr = i + 1; nr < npages; nr++) {
+ if (compound_head(list[nr]) != page)
+ break;
+ }
+
+ *head = page;
+ *ntails = nr - i;
+}
+
+#define for_each_compound_head(__i, __list, __npages, __head, __ntails) \
+ for (__i = 0, \
+ compound_next(__i, __npages, __list, &(__head), &(__ntails)); \
+ __i < __npages; __i += __ntails, \
+ compound_next(__i, __npages, __list, &(__head), &(__ntails)))
+
/**
* unpin_user_pages_dirty_lock() - release and optionally dirty gup-pinned pages
* @pages: array of pages to be maybe marked dirty, and definitely released.