Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756631Ab2HTOMq (ORCPT ); Mon, 20 Aug 2012 10:12:46 -0400 Received: from mx1.redhat.com ([209.132.183.28]:60212 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751765Ab2HTOMl (ORCPT ); Mon, 20 Aug 2012 10:12:41 -0400 Date: Mon, 20 Aug 2012 10:12:29 -0400 From: Mike Snitzer To: Christoph Hellwig Cc: "Martin K. Petersen" , Shaohua Li , Vivek Goyal , axboe@kernel.dk, linux-kernel@vger.kernel.org, neilb@suse.de, linux-scsi@vger.kernel.org Subject: Re: [patch 1/2]block: handle merged discard request Message-ID: <20120820141229.GC28570@redhat.com> References: <4F69C62C.7020604@kernel.org> <20120620085724.GA26295@infradead.org> <20120820135739.GB28570@redhat.com> <20120820135854.GA19254@infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20120820135854.GA19254@infradead.org> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 767 Lines: 17 On Mon, Aug 20 2012 at 9:58am -0400, Christoph Hellwig wrote: > On Mon, Aug 20, 2012 at 09:57:39AM -0400, Mike Snitzer wrote: > > But I haven't put my finger on _why_ a discard bio has bio->bi_io_vec > > (but given my use of DM, bio comes from bio_alloc_bioset, and DM passes > > original bio->bi_max_vecs for nr_iovecs). > > TRIM has a payload and we cheay by preallocation a data page for it. Thought we pushed that down? Hence sd_setup_discard_cmnd's alloc_page + blk_add_request_payload hack. -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/