From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755883AbaLWKWX (ORCPT ); Tue, 23 Dec 2014 05:22:23 -0500 Received: from bombadil.infradead.org ([198.137.202.9]:56237 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754743AbaLWKWV (ORCPT ); Tue, 23 Dec 2014 05:22:21 -0500 Date: Tue, 23 Dec 2014 02:22:21 -0800 From: Christoph Hellwig To: Dongsu Park Cc: linux-kernel@vger.kernel.org, Jens Axboe , Kent Overstreet , Ming Lin , target-devel@vger.kernel.org, Boaz Harrosh , Benny Halevy Subject: Re: [RFC PATCH 02/17] block: simplify bio_add_page() Message-ID: <20141223102221.GB13138@infradead.org> References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) X-SRS-Rewrite: SMTP reverse-path rewritten from by bombadil.infradead.org See http://www.infradead.org/rpr.html Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Dec 22, 2014 at 12:48:29PM +0100, Dongsu Park wrote: > From: Kent Overstreet > > Since generic_make_request() can now handle arbitrary size bios, all we > have to do is make sure the bvec array doesn't overflow. > __bio_add_page() doesn't need to call ->merge_bvec_fn(), where > we can get rid of unnecessary code paths. This needs an explanation of why removign the call to ->merge_bvec_fn is fine for bio_add_pc_page. I guess it's because neither the target pscsi pass through mode, nor the osd code ever use anything but a simple scsi devices that doesn't even have one, but it needs to be clearly spelled out. > + * Attempt to add a page to the bio_vec maplist. This will only fail if > + * bio->bi_vcnt == bio->bi_max_vecs. It also fails on a cloned bio, although that might better be turned into a BUG_ON().