From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754804AbaE1Ptj (ORCPT ); Wed, 28 May 2014 11:49:39 -0400 Received: from mx1.redhat.com ([209.132.183.28]:53890 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753841AbaE1Pth (ORCPT ); Wed, 28 May 2014 11:49:37 -0400 Date: Wed, 28 May 2014 17:49:26 +0200 From: Maurizio Lombardi To: Dongsu Park Cc: linux-kernel@vger.kernel.org, Dongsu Park , Jens Axboe , Jet Chen , Maurizio Lombardi , tom.leiming@gmail.com Subject: Re: [PATCH] bio: decrease bi_iter.bi_size by len in the fail path Message-ID: <20140528154925.GC2255@dhcp-27-189.brq.redhat.com> References: <20140527112459.GF2205@dhcp-27-189.brq.redhat.com> <1401289778-9840-1-git-send-email-dongsu.park@profitbricks.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1401289778-9840-1-git-send-email-dongsu.park@profitbricks.com> User-Agent: Mutt/1.5.23 (2014-03-12) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi, thanks for the patch On Wed, May 28, 2014 at 05:09:38PM +0200, Dongsu Park wrote: > From: Dongsu Park > > Commit 3979ef4dcf3d1de55a560a3a4016c30a835df44d ("bio-modify- > __bio_add_page-to-accept-pages-that-dont-start-a-new-segment-v3") > introduced a regression as reported by Jet Chen. > That results in a kernel BUG at drivers/block/virtio_blk.c:166. > > To fix that, bi_iter.bi_size must be decreased by len, before > recounting the number of physical segments. I don't understand exactly why it must be decreased by len. Can you provide more info? Thanks, Maurizio Lombardi > > Tested on with kernel 3.15.0-rc7-next-20140527 on qemu guest, > by running xfstests/ext4/271. > > Cc: Jens Axboe > Cc: Jet Chen > Cc: Maurizio Lombardi > Signed-off-by: Dongsu Park > --- > block/bio.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/block/bio.c b/block/bio.c > index 0443694ccbb4..67d7cba1e5fd 100644 > --- a/block/bio.c > +++ b/block/bio.c > @@ -810,6 +810,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page > bvec->bv_len = 0; > bvec->bv_offset = 0; > bio->bi_vcnt--; > + bio->bi_iter.bi_size -= len; > blk_recount_segments(q, bio); > return 0; > } > -- > 1.9.1 >