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Date: Tue, 14 Jul 2015 00:42:37 +0200
From: Oleg Nesterov <oleg@redhat.com>
To: Dave Chinner <david@fromorbit.com>
Cc: Al Viro <viro@zeniv.linux.org.uk>, Jan Kara <jack@suse.cz>,
        Linus Torvalds <torvalds@linux-foundation.org>,
        Paul McKenney <paulmck@linux.vnet.ibm.com>,
        Peter Zijlstra <peterz@infradead.org>,
        Daniel Wagner <daniel.wagner@bmw-carit.de>,
        Davidlohr Bueso <dave@stgolabs.net>, Ingo Molnar <mingo@redhat.com>,
        Tejun Heo <tj@kernel.org>, linux-kernel@vger.kernel.org,
        linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH RFC 0/4] change sb_writers to use percpu_rw_semaphore
Message-ID: <20150713224237.GA17003@redhat.com>
References: <20150713212536.GA13855@redhat.com> <20150713222309.GM3902@dastard>
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On 07/14, Dave Chinner wrote:
>
> [ Please cc linux-fsdevel@vger.kernel.org on filesystem
> infrastructure changes! ]

OK, will do.

> On Mon, Jul 13, 2015 at 11:25:36PM +0200, Oleg Nesterov wrote:
> >
> > 	- sb_lockdep_release() and sb_lockdep_acquire() play with
> > 	  percpu_rw_semaphore's internals.
> >
> > 	  Trivial, we need a couple of new helper in percpu-rwsem.c.
>
> 	- try compiling XFS, watch it break on freeze lockdep
> 	  annotations

Thanks a lot! I see. Still trivial, xfs can use the same helpers
rather the abuse lockdep directly.

> > 	- Most probably I missed something else, and I do not need
> > 	  how to test.
>
> xfstests has many freeze related stress tests.  IIRC, generic/068 is
> the test that historically causes the most problems for freeze
> infrastructure changes. You'll also need to test at least ext4, XFS
> and btrfs, because they all stress the freeze code differently.
> Testing XFS, in particular, is a good idea because it has several
> custom freeze tests that aren't run on any other filesystem type.

Thanks again.

Do you see something fundamentally wrong with this change?

Oleg.