vfs: export filemap_fdatawrite_range()

Make filemap_fdatawrite_range() function public, so that it can later
be used in ordered mode rewrite by JBD/JBD2.

Signed-off-by: Jan Kara <jack@suse.cz>
diff --git a/mm/filemap.c b/mm/filemap.c
index 1e6a7d3..65d9d9e 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -236,11 +236,12 @@
 }
 EXPORT_SYMBOL(filemap_fdatawrite);
 
-static int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
+int filemap_fdatawrite_range(struct address_space *mapping, loff_t start,
 				loff_t end)
 {
 	return __filemap_fdatawrite_range(mapping, start, end, WB_SYNC_ALL);
 }
+EXPORT_SYMBOL(filemap_fdatawrite_range);
 
 /**
  * filemap_flush - mostly a non-blocking flush