1 files changed, 24 insertions, 0 deletions

diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 66a0024becd9..7300c9d5e1d9 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -2290,3 +2290,27 @@ int mapping_tagged(struct address_space *mapping, int tag)
         return radix_tree_tagged(&mapping->page_tree, tag);
 }
 EXPORT_SYMBOL(mapping_tagged);
+
+/**
+ * wait_for_stable_page() - wait for writeback to finish, if necessary.
+ * @page:       The page to wait on.
+ *
+ * This function determines if the given page is related to a backing device
+ * that requires page contents to be held stable during writeback.  If so, then
+ * it will wait for any pending writeback to complete.
+ */
+void wait_for_stable_page(struct page *page)
+{
+        struct address_space *mapping = page_mapping(page);
+        struct backing_dev_info *bdi = mapping->backing_dev_info;
+
+        if (!bdi_cap_stable_pages_required(bdi))
+                return;
+#ifdef CONFIG_NEED_BOUNCE_POOL
+        if (mapping->host->i_sb->s_flags & MS_SNAP_STABLE)
+                return;
+#endif /* CONFIG_NEED_BOUNCE_POOL */
+
+        wait_on_page_writeback(page);
+}
+EXPORT_SYMBOL_GPL(wait_for_stable_page);