Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752029Ab1EXErx (ORCPT ); Tue, 24 May 2011 00:47:53 -0400 Received: from mail.parknet.co.jp ([210.171.160.6]:58193 "EHLO mail.parknet.co.jp" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751127Ab1EXErv (ORCPT ); Tue, 24 May 2011 00:47:51 -0400 From: OGAWA Hirofumi To: Kyungmin Park Cc: Arnd Bergmann , Lukas Czerner , linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org Subject: Re: [PATCH v6] fat: Batched discard support for fat References: <20110328103431.GA22323@july> <201103301620.50263.arnd@arndb.de> <201103301706.36214.arnd@arndb.de> Date: Tue, 24 May 2011 13:47:46 +0900 In-Reply-To: (Kyungmin Park's message of "Tue, 24 May 2011 10:18:20 +0900") Message-ID: <87wrhgk8lp.fsf@devron.myhome.or.jp> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/24.0.50 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1636 Lines: 49 Kyungmin Park writes: > Hi again, Hi > Do you still object to merge this feature for .40? As I said the > batched discard design is out-of-scope of this patch. > It's implemented at other batched discard, ext4, xfs and so on. > > I hope fat is also support the batched discard. > > Any opinions? I'm also thinking implementing this is good though. Sorry, I'm not going to apply this for now, and would like to wait to be used by real userland (I hope guys notice the problem, or userland tackles it somehow sadly). I think, to expose the wrong behavior like this would be worse. E.g. one of problems, userland might do like this (trim chunk from 0 to number of block) for chunk in number_of_blocks do_trim chunk done But this is actually wrong, this interface doesn't map blocks to 0-max, so userland have to know real maximum-block-number somehow for each FS (and maybe have to know real minimum-block-number). So, how to fix this? The solutions would be userland workaround, or fix kernel. If it was userland, userland have to know FS internal sadly. If it was kernel, we would have backward compatible nightmare, or ignore compatible :(. I really think we have to rethink this and have agreement about common interface. Or there was real userland app, I think FAT can implement to work that app. Thanks. -- OGAWA Hirofumi -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/