From mboxrd@z Thu Jan 1 00:00:00 1970 From: Jens Axboe Subject: Re: [PATCH] [14/20] Don't disable direct_io for unchecked_isa_dma in st.c Date: Mon, 17 Mar 2008 09:28:07 +0100 Message-ID: <20080317082807.GD17940@kernel.dk> References: <20080307653.720459648@firstfloor.org> <20080307175414.08C981B41AE@basil.firstfloor.org> <20080314135135.GT17940@kernel.dk> <20080314142412.GA30325@infradead.org> <47DD14F7.4070607@panasas.com> <20080316124409.GB613@one.firstfloor.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from brick.kernel.dk ([87.55.233.238]:15721 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752016AbYCQI2K (ORCPT ); Mon, 17 Mar 2008 04:28:10 -0400 Content-Disposition: inline In-Reply-To: <20080316124409.GB613@one.firstfloor.org> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Andi Kleen Cc: Boaz Harrosh , Christoph Hellwig , Mike Christie , James.Bottomley@HansenPartnership.com, linux-scsi@vger.kernel.org On Sun, Mar 16 2008, Andi Kleen wrote: > On Sun, Mar 16, 2008 at 02:39:19PM +0200, Boaz Harrosh wrote: > > On Fri, Mar 14 2008 at 16:24 +0200, Christoph Hellwig wrote: > > > On Fri, Mar 14, 2008 at 02:51:35PM +0100, Jens Axboe wrote: > > >> Are you sure? Seems to me that st builds its own list with > > >> get_user_pages() for direct io, where will that get bounced? The block > > >> layer will only bounce things that are mapped directly, so if st used > > >> blk_rq_map_kern() and inserted that request in the queue, we could > > >> proceed with killing that check in st. > > > > > > Which shouldn't be all too difficult and would be the right thing to > > > do. We really need someone to sit down and convert st/osst/sg to use > > > the proper block layer helpers. > > > > > > > First they do. They all call scsi_execute_async which at the end produces > > a BIO and then calls blk_execute_nowait(). and all is swell. > > I thought i had audited them all too, but wasn't 100% sure anymore. > But thanks for double checking. > > Jens, that answers your earlier question. OK good, I didn't realize that that path was already done. No problem with this part, then. -- Jens Axboe