From: =?ISO-8859-15?Q?Luk=E1=A8_Czerner?= Subject: Re: [PATCH] ext4: Do not destroy ext4_groupinfo_caches if ext4_mb_init() fails Date: Tue, 13 May 2014 12:25:23 +0200 (CEST) Message-ID: References: <1399883039-2978-1-git-send-email-tsyvarev@ispras.ru> <5371F135.7040409@ispras.ru> Mime-Version: 1.0 Content-Type: MULTIPART/MIXED; BOUNDARY="8323328-1568388389-1399976726=:2070" Cc: "Theodore Ts'o" , Andreas Dilger , linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, Alexey Khoroshilov To: Andrey Tsyvarev Return-path: Received: from mx1.redhat.com ([209.132.183.28]:58240 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S932564AbaEMKZl (ORCPT ); Tue, 13 May 2014 06:25:41 -0400 In-Reply-To: <5371F135.7040409@ispras.ru> Sender: linux-ext4-owner@vger.kernel.org List-ID: This message is in MIME format. The first part should be readable text, while the remaining parts are likely unreadable without MIME-aware tools. --8323328-1568388389-1399976726=:2070 Content-Type: TEXT/PLAIN; charset=UTF-8 Content-Transfer-Encoding: 8BIT On Tue, 13 May 2014, Andrey Tsyvarev wrote: > Date: Tue, 13 May 2014 14:17:25 +0400 > From: Andrey Tsyvarev > To: Lukáš Czerner > Cc: Theodore Ts'o , Andreas Dilger , > linux-ext4@vger.kernel.org, linux-kernel@vger.kernel.org, > Alexey Khoroshilov > Subject: Re: [PATCH] ext4: Do not destroy ext4_groupinfo_caches if > ext4_mb_init() fails > > > 12.05.2014 19:08, Lukáš Czerner пишет: > > On Mon, 12 May 2014, Andrey Tsyvarev wrote: > > > > > Date: Mon, 12 May 2014 12:23:59 +0400 > > > From: Andrey Tsyvarev > > > To: Theodore Ts'o > > > Cc: Andrey Tsyvarev, > > > Andreas Dilger,linux-ext4@vger.kernel.org, > > > linux-kernel@vger.kernel.org, Alexey > > > Khoroshilov > > > Subject: [PATCH] ext4: Do not destroy ext4_groupinfo_caches if > > > ext4_mb_init() > > > fails > > > > > > Caches from 'ext4_groupinfo_caches' may be in use by other mounts, which > > > have already existed. > > > So, it is incorrect to destroy them when newly requested mount fails. > > > > > > Found by Linux File System Verification project (linuxtesting.org). > > Makes sense, thanks! Can you please share the test case which > > triggered this ? It might be worth including in xfstests. > > Actually it was triggered by xfstests themselves but run with fault > simulation. > The method of fault simulation is under development/evaluation now, we expect > to publish a paper describing it in the near future. > > BUG_ON() in get_groupinfo_cache() was firstly triggered by test generic/003, > but actually it could be any other test, which uses a scratch device: xftests > itself requires test device(TEST_DEV) mounted, so a fault simulated while > mount scratch device causes the problem described. It sounds interesting. I hope that you'll send the information out to the fsdevel list when your paper is finished, It looks like it might be quite useful. Thanks! -Lukas > > > > Reviewed-by: Lukas Czerner > > > > > Signed-off-by: Andrey Tsyvarev > > > --- > > > fs/ext4/mballoc.c | 4 +--- > > > 1 file changed, 1 insertion(+), 3 deletions(-) > > > > > > diff --git a/fs/ext4/mballoc.c b/fs/ext4/mballoc.c > > > index 04a5c75..becea1d 100644 > > > --- a/fs/ext4/mballoc.c > > > +++ b/fs/ext4/mballoc.c > > > @@ -2607,7 +2607,7 @@ int ext4_mb_init(struct super_block *sb) > > > sbi->s_locality_groups = alloc_percpu(struct ext4_locality_group); > > > if (sbi->s_locality_groups == NULL) { > > > ret = -ENOMEM; > > > - goto out_free_groupinfo_slab; > > > + goto out; > > > } > > > for_each_possible_cpu(i) { > > > struct ext4_locality_group *lg; > > > @@ -2632,8 +2632,6 @@ int ext4_mb_init(struct super_block *sb) > > > out_free_locality_groups: > > > free_percpu(sbi->s_locality_groups); > > > sbi->s_locality_groups = NULL; > > > -out_free_groupinfo_slab: > > > - ext4_groupinfo_destroy_slabs(); > > > out: > > > kfree(sbi->s_mb_offsets); > > > sbi->s_mb_offsets = NULL; > > > > > -- > Andrey Tsyvarev > Linux Verification Center, ISPRAS > > --8323328-1568388389-1399976726=:2070--