From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754202Ab0F1Mlc (ORCPT ); Mon, 28 Jun 2010 08:41:32 -0400 Received: from 0122700014.0.fullrate.dk ([95.166.99.235]:43339 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751298Ab0F1Mla (ORCPT ); Mon, 28 Jun 2010 08:41:30 -0400 Message-ID: <4C28987A.7000701@kernel.dk> Date: Mon, 28 Jun 2010 14:41:30 +0200 From: Jens Axboe MIME-Version: 1.0 To: Mike Snitzer 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 References: <20100622180029.GA15950@redhat.com> <1277582211-10725-2-git-send-email-snitzer@redhat.com> <4C2896C6.9030607@kernel.dk> <20100628123742.GB19497@redhat.com> In-Reply-To: <20100628123742.GB19497@redhat.com> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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? -- Jens Axboe