linux-kernel - Re: [PATCH V2 2/2] fs/super.c: don't fool lockdep in freeze_super() and thaw

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Date:   Tue, 27 Sep 2016 17:14:04 +1000
From:   Dave Chinner <david@...morbit.com>
To:     Jan Kara <jack@...e.cz>
Cc:     Oleg Nesterov <oleg@...hat.com>, Al Viro <viro@...iv.linux.org.uk>,
        Nikolay Borisov <kernel@...p.com>,
        "Paul E. McKenney" <paulmck@...ux.vnet.ibm.com>,
        linux-fsdevel@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH V2 2/2] fs/super.c: don't fool lockdep in freeze_super()
 and thaw_super() paths

On Tue, Sep 27, 2016 at 08:51:35AM +0200, Jan Kara wrote:
> On Mon 26-09-16 18:55:25, Oleg Nesterov wrote:
> > On 09/26, Jan Kara wrote:
> > >
> > > On Mon 26-09-16 18:08:06, Oleg Nesterov wrote:
> > > > +/*
> > > > + * Tell lockdep we are holding these locks before we call ->unfreeze_fs(sb).
> > > > + */
> > > > +static void sb_freeze_acquire(struct super_block *sb)
> > >
> > > Can we call this lockdep_sb_freeze_acquire() or something like that so that
> > > it is clear this is only about lockdep annotations? Similarly with
> > > sb_freeze_unlock()...
> > 
> > OK, thanks, done. See V2 below.
> > 
> > > and I hope you really tested
> > > there are no more lockdep false positives ;).
> > 
> > Heh ;) if only I knew how to test this... I ran the following script
> > under qemu
> > 
> > 	mkfs.xfs -f /dev/vda
> > 	mkfs.xfs -f /dev/vdb
> > 
> > 	mkdir -p TEST SCRATCH
> > 
> > 	TEST_DEV=/dev/vda TEST_DIR=TEST SCRATCH_DEV=/dev/vdb SCRATCH_MNT=SCRATCH \
> > 	./check `grep -il freeze tests/*/???`
> 
> You can run either:
> 
> 	./check -g freeze
> 
> to check just the freezing tests or
> 
> 	./check

Better for regression testing is:

check -g auto

so that is skips all the tests that are broken or likely to crash
the machine on some debug check.

Cheers,

Dave.
-- 
Dave Chinner
david@...morbit.com