1 files changed, 15 insertions, 0 deletions

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index 0a2f5d27f60e..64f950925151 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -130,14 +130,29 @@ static inline pgoff_t linear_page_index(struct vm_area_struct *vma,
 }
 
 extern void FASTCALL(__lock_page(struct page *page));
+extern void FASTCALL(__lock_page_nosync(struct page *page));
 extern void FASTCALL(unlock_page(struct page *page));
 
+/*
+ * lock_page may only be called if we have the page's inode pinned.
+ */
 static inline void lock_page(struct page *page)
 {
         might_sleep();
         if (TestSetPageLocked(page))
                 __lock_page(page);
 }
+
+/*
+ * lock_page_nosync should only be used if we can't pin the page's inode.
+ * Doesn't play quite so well with block device plugging.
+ */
+static inline void lock_page_nosync(struct page *page)
+{
+        might_sleep();
+        if (TestSetPageLocked(page))
+                __lock_page_nosync(page);
+}
         
 /*
  * This is exported only for wait_on_page_locked/wait_on_page_writeback.