From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754498Ab0F1MqO (ORCPT ); Mon, 28 Jun 2010 08:46:14 -0400 Received: from mx1.redhat.com ([209.132.183.28]:13495 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754185Ab0F1MqJ (ORCPT ); Mon, 28 Jun 2010 08:46:09 -0400 Date: Mon, 28 Jun 2010 08:45:48 -0400 From: Mike Snitzer To: Jens Axboe Cc: Christoph Hellwig , dm-devel@redhat.com, James.Bottomley@suse.de, linux-kernel@vger.kernel.org, martin.petersen@oracle.com, akpm@linux-foundation.org Subject: Re: [PATCH 2/2] block: defer the use of inline biovecs for discard requests Message-ID: <20100628124548.GC19497@redhat.com> References: <20100622180029.GA15950@redhat.com> <1277582211-10725-2-git-send-email-snitzer@redhat.com> <4C2896C6.9030607@kernel.dk> <20100628123742.GB19497@redhat.com> <4C28987A.7000701@kernel.dk> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <4C28987A.7000701@kernel.dk> User-Agent: Mutt/1.5.20 (2009-08-17) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Jun 28 2010 at 8:41am -0400, Jens Axboe wrote: > On 2010-06-28 14:37, Mike Snitzer wrote: > > On Mon, Jun 28 2010 at 8:34am -0400, > > Jens Axboe wrote: > > > >> On 2010-06-26 21:56, Mike Snitzer wrote: > >>> Don't alloc discard bio with a biovec in blkdev_issue_discard. Doing so > >>> means bio_has_data() will not be true until the SCSI layer adds the > >>> payload to the discard request via blk_add_request_payload. > >> > >> Sorry, this looks horrible. > > > > Your judgment isn't giving me much to work with... not sure where I go > > with "horrible". > > The horrible part is working around that issue by fiddling with the > assignment of the internal vec. THAT looks like a horrible solution > to that problem. > > How about just adding a check to bio_has_data() for non-zero > bio->bi_vcnt? Sure, that works.