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Message-ID: <alpine.LFD.2.00.1405131223410.2070@localhost.localdomain> Date: Tue, 13 May 2014 12:25:23 +0200 (CEST) From: Lukáš Czerner <lczerner@...hat.com> To: Andrey Tsyvarev <tsyvarev@...ras.ru> cc: "Theodore Ts'o" <tytso@....edu>, Andreas Dilger <adilger.kernel@...ger.ca>, linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org, Alexey Khoroshilov <khoroshilov@...ras.ru> Subject: Re: [PATCH] ext4: Do not destroy ext4_groupinfo_caches if ext4_mb_init() fails On Tue, 13 May 2014, Andrey Tsyvarev wrote: > Date: Tue, 13 May 2014 14:17:25 +0400 > From: Andrey Tsyvarev <tsyvarev@...ras.ru> > To: Lukáš Czerner <lczerner@...hat.com> > Cc: Theodore Ts'o <tytso@....edu>, Andreas Dilger <adilger.kernel@...ger.ca>, > linux-ext4@...r.kernel.org, linux-kernel@...r.kernel.org, > Alexey Khoroshilov <khoroshilov@...ras.ru> > 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<tsyvarev@...ras.ru> > > > To: Theodore Ts'o<tytso@....edu> > > > Cc: Andrey Tsyvarev<tsyvarev@...ras.ru>, > > > Andreas Dilger<adilger.kernel@...ger.ca>,linux-ext4@...r.kernel.org, > > > linux-kernel@...r.kernel.org, Alexey > > > Khoroshilov<khoroshilov@...ras.ru> > > > 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<lczerner@...hat.com> > > > > > Signed-off-by: Andrey Tsyvarev<tsyvarev@...ras.ru> > > > --- > > > 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 > >
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