constify dentry_operations: OCFS2

Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>
diff --git a/fs/ocfs2/dcache.h b/fs/ocfs2/dcache.h
index d06e16c..faa12e7 100644
--- a/fs/ocfs2/dcache.h
+++ b/fs/ocfs2/dcache.h
@@ -26,7 +26,7 @@
 #ifndef OCFS2_DCACHE_H
 #define OCFS2_DCACHE_H
 
-extern struct dentry_operations ocfs2_dentry_ops;
+extern const struct dentry_operations ocfs2_dentry_ops;
 
 struct ocfs2_dentry_lock {
 	/* Use count of dentry lock */