From mboxrd@z Thu Jan 1 00:00:00 1970 From: Andi Kleen Subject: Re: [PATCH] [14/20] Don't disable direct_io for unchecked_isa_dma in st.c Date: Sun, 16 Mar 2008 13:44:09 +0100 Message-ID: <20080316124409.GB613@one.firstfloor.org> References: <20080307653.720459648@firstfloor.org> <20080307175414.08C981B41AE@basil.firstfloor.org> <20080314135135.GT17940@kernel.dk> <20080314142412.GA30325@infradead.org> <47DD14F7.4070607@panasas.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from one.firstfloor.org ([213.235.205.2]:40806 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752837AbYCPMlu (ORCPT ); Sun, 16 Mar 2008 08:41:50 -0400 Content-Disposition: inline In-Reply-To: <47DD14F7.4070607@panasas.com> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Boaz Harrosh Cc: Christoph Hellwig , Jens Axboe , Mike Christie , Andi Kleen , James.Bottomley@HansenPartnership.com, linux-scsi@vger.kernel.org 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. -Andi