From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756731AbaE2GIU (ORCPT ); Thu, 29 May 2014 02:08:20 -0400 Received: from mga02.intel.com ([134.134.136.20]:61319 "EHLO mga02.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751010AbaE2GIT (ORCPT ); Thu, 29 May 2014 02:08:19 -0400 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.98,932,1392192000"; d="scan'208";a="519487777" Message-ID: <5386CE5A.6070708@intel.com> Date: Thu, 29 May 2014 14:06:18 +0800 From: Jet Chen User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:24.0) Gecko/20100101 Thunderbird/24.5.0 MIME-Version: 1.0 To: Ming Lei , Maurizio Lombardi CC: Linux Kernel Mailing List , Jens Axboe , Dongsu Park , Fengguang Wu Subject: Re: [PATCH] bio: decrease bi_iter.bi_size by len in the fail path References: <20140527112459.GF2205@dhcp-27-189.brq.redhat.com> <1401289778-9840-1-git-send-email-dongsu.park@profitbricks.com> <20140528172150.GA3261@dhcp-27-189.brq.redhat.com> In-Reply-To: Content-Type: multipart/mixed; boundary="------------010606000708080507030805" Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org This is a multi-part message in MIME format. --------------010606000708080507030805 Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit On 05/29/2014 01:44 AM, Ming Lei wrote: > On Thu, May 29, 2014 at 1:21 AM, Maurizio Lombardi wrote: >> Hi Ming, >> >> On Thu, May 29, 2014 at 12:59:19AM +0800, Ming Lei wrote: >>> >>> Actually, the correct thing may be like what did in the >>> attached patch, as Maurizio discussed with me[1]. >>> >>> Very interestingly, I have reproduced the problem one time >>> with ext4/271 ext4/301 ext4/305, but won't with the attached >>> patch after running it for 3 rounds. >>> >>> [tom@localhost xfstests]$ sudo ./check ext4/271 ext4/301 ext4/305 >>> FSTYP -- ext4 >>> PLATFORM -- Linux/x86_64 localhost 3.15.0-rc7-next-20140527+ >>> MKFS_OPTIONS -- /dev/vdc >>> MOUNT_OPTIONS -- -o acl,user_xattr /dev/vdc /mnt/scratch >>> >>> ext4/271 1s ... 1s >>> ext4/301 31s ... 32s >>> ext4/305 181s ... 180s >>> Ran: ext4/271 ext4/301 ext4/305 >>> Passed all 3 tests >>> >>> Jet, could you test the attached patch? >>> >>> [1], https://lkml.org/lkml/2014/5/27/327 >> >> There is a little mistake in your patch, you removed bio->bi_iter.bi_size += len; >> after the "done" label, >> but be careful that at line 747 there is a "goto done"... bi_size should be incremented >> before jumping there. > > Good catch, thanks Maurizio. > > Jet, please test the attached patch in this mail and ignore previous > one. > > The story behind the patch should be like below: > > - one page is added in __bio_add_page() 'successfully', > and bio->bi_phys_segments is equal to queue_max_segments(q), > but it should have been rejected since the last vector isn't covered > > - next time, __bio_add_page() is called to add one page, but this > time blk_recount_segments() can figure out the actual physical > segments and find it is more than max segments, so failure is > triggered, but the bio->bi_phys_segments is updated with > max segments plus one > > - the oops is triggered and reported by Jet, :-) > > > Thanks, > This patch works, thanks. Tested-by: Jet Chen --------------010606000708080507030805 Content-Type: text/x-patch; name="fix_compute_segments.patch" Content-Transfer-Encoding: 7bit Content-Disposition: attachment; filename="fix_compute_segments.patch" diff --git a/block/bio.c b/block/bio.c index 0443694..f9bae56 100644 --- a/block/bio.c +++ b/block/bio.c @@ -744,6 +744,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page } } + bio->bi_iter.bi_size += len; goto done; } } @@ -761,6 +762,7 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page bvec->bv_offset = offset; bio->bi_vcnt++; bio->bi_phys_segments++; + bio->bi_iter.bi_size += len; /* * Perform a recount if the number of segments is greater @@ -802,7 +804,6 @@ static int __bio_add_page(struct request_queue *q, struct bio *bio, struct page bio->bi_flags &= ~(1 << BIO_SEG_VALID); done: - bio->bi_iter.bi_size += len; return len; failed: @@ -810,6 +811,7 @@ 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; } --------------010606000708080507030805--