ext4: Use a hash of the topdir directory name for the Orlov parent group

Instead of using a random number to determine the goal parent grop for
the Orlov top directories, use a hash of the directory name.  This
allows for repeatable results when trying to benchmark filesystem
layout algorithms.

Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
diff --git a/fs/ext4/migrate.c b/fs/ext4/migrate.c
index fe64d9f..80d075b 100644
--- a/fs/ext4/migrate.c
+++ b/fs/ext4/migrate.c
@@ -483,9 +483,8 @@
 		retval = PTR_ERR(handle);
 		return retval;
 	}
-	tmp_inode = ext4_new_inode(handle,
-				inode->i_sb->s_root->d_inode,
-				S_IFREG);
+	tmp_inode = ext4_new_inode(handle, inode->i_sb->s_root->d_inode,
+				   S_IFREG, 0);
 	if (IS_ERR(tmp_inode)) {
 		retval = -ENOMEM;
 		ext4_journal_stop(handle);