From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pf0-f200.google.com (mail-pf0-f200.google.com [209.85.192.200]) by kanga.kvack.org (Postfix) with ESMTP id 9091B6B0279 for ; Tue, 27 Jun 2017 02:12:16 -0400 (EDT) Received: by mail-pf0-f200.google.com with SMTP id d5so18815574pfe.2 for ; Mon, 26 Jun 2017 23:12:16 -0700 (PDT) Received: from bombadil.infradead.org (bombadil.infradead.org. [65.50.211.133]) by mx.google.com with ESMTPS id i16si1330276pfj.91.2017.06.26.23.12.15 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Mon, 26 Jun 2017 23:12:15 -0700 (PDT) Date: Mon, 26 Jun 2017 23:12:11 -0700 From: Matthew Wilcox 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> Sender: owner-linux-mm@kvack.org List-ID: 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 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? -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org