From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752694AbcFVUdS (ORCPT ); Wed, 22 Jun 2016 16:33:18 -0400 Received: from mail-lf0-f47.google.com ([209.85.215.47]:33088 "EHLO mail-lf0-f47.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752550AbcFVUdO (ORCPT ); Wed, 22 Jun 2016 16:33:14 -0400 MIME-Version: 1.0 In-Reply-To: <20160622170257.GS14480@ZenIV.linux.org.uk> References: <1466606110-24297-1-git-send-email-mszeredi@redhat.com> <1466606110-24297-2-git-send-email-mszeredi@redhat.com> <20160622170257.GS14480@ZenIV.linux.org.uk> From: Miklos Szeredi Date: Wed, 22 Jun 2016 22:33:12 +0200 Message-ID: Subject: Re: [PATCH 1/8] vfs: new d_allocate method To: Al Viro Cc: lkml , linux-fsdevel Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jun 22, 2016 at 7:02 PM, Al Viro wrote: > On Wed, Jun 22, 2016 at 04:35:03PM +0200, Miklos Szeredi wrote: >> Allow filesystem to initialize dentry (->d_fsdata to be explicit) at >> allocation time. > > Something similar had been discussed a while ago (I don't remember whether > you'd been on Cc, though). E.g. ceph and lustre would benefit from having > such method (proposed name was ->d_init(), seeing that it's not always > just an allocation). The subtle part is barriers and I would really like > to see a proof that you don't need any. Thanks for the review. Yeah, I missed the rcu concequences. And I also didn't benchmark anything, it's obviously going to hurt somewhat for fs that need to alloc an fsdata due to this. I'm waiting to hear better ideas. One, rather ugly, is to make the max internal name length fs depenent, and allow fs to use that space if it wants to trading it for a longer d_iname. Thaks, Miklos