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-rw-r--r--include/linux/mm.h33
1 files changed, 33 insertions, 0 deletions
diff --git a/include/linux/mm.h b/include/linux/mm.h
index d87a5a5fe87..f3fd70d6029 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -833,6 +833,39 @@ extern int mprotect_fixup(struct vm_area_struct *vma,
struct vm_area_struct **pprev, unsigned long start,
unsigned long end, unsigned long newflags);
+#ifdef CONFIG_HAVE_GET_USER_PAGES_FAST
+/*
+ * get_user_pages_fast provides equivalent functionality to get_user_pages,
+ * operating on current and current->mm (force=0 and doesn't return any vmas).
+ *
+ * get_user_pages_fast may take mmap_sem and page tables, so no assumptions
+ * can be made about locking. get_user_pages_fast is to be implemented in a
+ * way that is advantageous (vs get_user_pages()) when the user memory area is
+ * already faulted in and present in ptes. However if the pages have to be
+ * faulted in, it may turn out to be slightly slower).
+ */
+int get_user_pages_fast(unsigned long start, int nr_pages, int write,
+ struct page **pages);
+
+#else
+/*
+ * Should probably be moved to asm-generic, and architectures can include it if
+ * they don't implement their own get_user_pages_fast.
+ */
+#define get_user_pages_fast(start, nr_pages, write, pages) \
+({ \
+ struct mm_struct *mm = current->mm; \
+ int ret; \
+ \
+ down_read(&mm->mmap_sem); \
+ ret = get_user_pages(current, mm, start, nr_pages, \
+ write, 0, pages, NULL); \
+ up_read(&mm->mmap_sem); \
+ \
+ ret; \
+})
+#endif
+
/*
* A callback you can register to apply pressure to ageable caches.
*