From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jeff Garzik Subject: Re: [PATCHSET pata-2.6] ide: rq->buffer, data, special and misc cleanups Date: Mon, 13 Apr 2009 04:31:08 -0400 Message-ID: <49E2F84C.6080804@garzik.org> References: <49D214E7.2040908@panasas.com> <20090413163957P.fujita.tomonori@lab.ntt.co.jp> <49E2EFBE.5000709@garzik.org> <20090413172143B.fujita.tomonori@lab.ntt.co.jp> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Return-path: Received: from srv5.dvmed.net ([207.36.208.214]:55302 "EHLO mail.dvmed.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753422AbZDMIbP (ORCPT ); Mon, 13 Apr 2009 04:31:15 -0400 In-Reply-To: <20090413172143B.fujita.tomonori@lab.ntt.co.jp> Sender: linux-ide-owner@vger.kernel.org List-Id: linux-ide@vger.kernel.org To: FUJITA Tomonori Cc: bharrosh@panasas.com, tj@kernel.org, petkovbb@gmail.com, bzolnier@gmail.com, linux-kernel@vger.kernel.org, axboe@kernel.dk, linux-ide@vger.kernel.org FUJITA Tomonori wrote: > On Mon, 13 Apr 2009 03:54:38 -0400 > Jeff Garzik wrote: > >> FUJITA Tomonori wrote: >>> On Tue, 31 Mar 2009 16:04:39 +0300 >>> Boaz Harrosh wrote: >>> >>>>> I >>>>> just don't think bvec should be used outside of block/fs interface. >>>>> As I wrote before, non-FS users have no reason to worry about bio. >>>>> All it should think about is the requst it needs to issue and the >>>>> memory area it's gonna use as in/out buffers. bio just doesn't have a >>>>> place there. >>>>> >>>> I don't understand what happens to all the people that start to work on the block >>>> layer, they start getting defensive about bio being private to the request >>>> level. But the Genie is out of the bag already (I know cats and bottles). >>>> bio is already heavily used above the block layer from directly inside filesystems >>>> to all kind of raid engines, DM MD managers, multi paths, integrity information ... >>>> >>>> Because bio is exactly that Ideal page carrier you are talking about. >>> Wrong. multi path doesn't use bio. md accesses to the bio internal >>> (it's not nice) and has the own way to carry pages. dm has the own >>> mechanism on the top of bio. And bio doesn't work nicely for file >>> systems such as btrfs, which handle multiple devices. >>> >>> Please stop your wrong argument 'bio is the ideal page carrier'. >> What is the multi-device problem with bio? > > Well, if it works nicely, I guess that we don't have something like > drivers/dm/{dm-bio-record.h, dm-bio-list.h}, btrfs_multi_bio struct, > or md's own page carrier? It was an honest question. I am seeking information, not denying your argument. What, specifically, is this multi-device problem with bio, please? Jeff