1 files changed, 33 insertions, 0 deletions

diff --git a/include/linux/mm.h b/include/linux/mm.h
index d87a5a5fe87d..f3fd70d6029f 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.
  *