Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751723AbdF0GMW (ORCPT ); Tue, 27 Jun 2017 02:12:22 -0400 Received: from bombadil.infradead.org ([65.50.211.133]:39145 "EHLO bombadil.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751412AbdF0GMP (ORCPT ); Tue, 27 Jun 2017 02:12:15 -0400 Date: Mon, 26 Jun 2017 23:12:11 -0700 From: Matthew Wilcox To: Ming Lei Cc: Jens Axboe , Christoph Hellwig , Huang Ying , Andrew Morton , Alexander Viro , linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v2 16/51] block: bounce: avoid direct access to bvec table Message-ID: <20170627061211.GA27359@bombadil.infradead.org> References: <20170626121034.3051-1-ming.lei@redhat.com> <20170626121034.3051-17-ming.lei@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20170626121034.3051-17-ming.lei@redhat.com> User-Agent: Mutt/1.8.0 (2017-02-23) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 869 Lines: 29 On Mon, Jun 26, 2017 at 08:09:59PM +0800, Ming Lei wrote: > bio_for_each_segment_all(bvec, bio, i) { > - org_vec = bio_orig->bi_io_vec + i + start; > - > - if (bvec->bv_page == org_vec->bv_page) > - continue; > + orig_vec = bio_iter_iovec(bio_orig, orig_iter); > + if (bvec->bv_page == orig_vec.bv_page) > + goto next; > > dec_zone_page_state(bvec->bv_page, NR_BOUNCE); > mempool_free(bvec->bv_page, pool); > + next: > + bio_advance_iter(bio_orig, &orig_iter, orig_vec.bv_len); > } > I think this might be written more clearly as: bio_for_each_segment_all(bvec, bio, i) { orig_vec = bio_iter_iovec(bio_orig, orig_iter); if (bvec->bv_page != orig_vec.bv_page) { dec_zone_page_state(bvec->bv_page, NR_BOUNCE); mempool_free(bvec->bv_page, pool); } bio_advance_iter(bio_orig, &orig_iter, orig_vec.bv_len); } What do you think?