Add readdir() on mountpoints

git-svn-id: svn://svn.code.sf.net/p/nuttx/code/trunk@251 42af7a65-404d-4744-a932-0658087f49c3

include/nuttx/fs.h

@@ -145,6 +145,10 @@ struct mountpt_operations
 
   int     (*sync)(FAR struct file *filp);
 
+  /* Directory operations */
+
+  int     (*opendir)(struct inode *mountpt, const char *relpath, struct internal_dir_s *dir);
+
   /* General volume-related mountpoint operations: */
 
   int     (*bind)(FAR struct inode *blkdriver, const void *data, void **handle);