ocfs2: Add dir_resv_level mount option

The default behavior for directory reservations stays the same, but we add a
mount option so people can tweak the size of directory reservations
according to their workloads.

Signed-off-by: Mark Fasheh <mfasheh@suse.com>
Signed-off-by: Joel Becker <joel.becker@oracle.com>
diff --git a/fs/ocfs2/reservations.h b/fs/ocfs2/reservations.h
index 022aff6..25b0c0e 100644
--- a/fs/ocfs2/reservations.h
+++ b/fs/ocfs2/reservations.h
@@ -67,6 +67,8 @@
 void ocfs2_resv_set_type(struct ocfs2_alloc_reservation *resv,
 			 unsigned int flags);
 
+int ocfs2_dir_resv_allowed(struct ocfs2_super *osb);
+
 /**
  * ocfs2_resv_discard() - truncate a reservation
  * @resmap: