Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752519AbdHHIrs (ORCPT ); Tue, 8 Aug 2017 04:47:48 -0400 Received: from mx1.redhat.com ([209.132.183.28]:45792 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752093AbdHHIrq (ORCPT ); Tue, 8 Aug 2017 04:47:46 -0400 DMARC-Filter: OpenDMARC Filter v1.3.2 mx1.redhat.com F063D883C3 Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; dmarc=none (p=none dis=none) header.from=redhat.com Authentication-Results: ext-mx02.extmail.prod.ext.phx2.redhat.com; spf=fail smtp.mailfrom=ming.lei@redhat.com From: Ming Lei To: Jens Axboe , Christoph Hellwig , Huang Ying , Andrew Morton , Alexander Viro Cc: linux-kernel@vger.kernel.org, linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-mm@kvack.org, Ming Lei Subject: [PATCH v3 09/49] block: comment on bio_iov_iter_get_pages() Date: Tue, 8 Aug 2017 16:45:08 +0800 Message-Id: <20170808084548.18963-10-ming.lei@redhat.com> In-Reply-To: <20170808084548.18963-1-ming.lei@redhat.com> References: <20170808084548.18963-1-ming.lei@redhat.com> X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.26]); Tue, 08 Aug 2017 08:47:46 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 847 Lines: 26 bio_iov_iter_get_pages() used unused bvec spaces for storing page pointer array temporarily, and this patch comments on this usage wrt. multipage bvec support. Signed-off-by: Ming Lei --- block/bio.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/block/bio.c b/block/bio.c index 826b5d173416..28697e3c8ce3 100644 --- a/block/bio.c +++ b/block/bio.c @@ -875,6 +875,10 @@ EXPORT_SYMBOL(bio_add_page); * * Pins as many pages from *iter and appends them to @bio's bvec array. The * pages will have to be released using put_page() when done. + * + * The hacking way of using bvec table as page pointer array is safe + * even after multipage bvec is introduced because that space can be + * thought as unused by bio_add_page(). */ int bio_iov_iter_get_pages(struct bio *bio, struct iov_iter *iter) { -- 2.9.4