From mboxrd@z Thu Jan 1 00:00:00 1970 From: Christoph Hellwig Subject: Re: [PATCH] [14/20] Don't disable direct_io for unchecked_isa_dma in st.c Date: Fri, 14 Mar 2008 10:24:12 -0400 Message-ID: <20080314142412.GA30325@infradead.org> References: <20080307653.720459648@firstfloor.org> <20080307175414.08C981B41AE@basil.firstfloor.org> <20080314135135.GT17940@kernel.dk> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from bombadil.infradead.org ([18.85.46.34]:39678 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750876AbYCNOYV (ORCPT ); Fri, 14 Mar 2008 10:24:21 -0400 Content-Disposition: inline In-Reply-To: <20080314135135.GT17940@kernel.dk> Sender: linux-scsi-owner@vger.kernel.org List-Id: linux-scsi@vger.kernel.org To: Jens Axboe Cc: Andi Kleen , James.Bottomley@HansenPartnership.com, linux-scsi@vger.kernel.org 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.