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Subject: Re: [PATCH RFC] kernel/locking, fs/direct-io: Introduce and use
 down_write_nolockdep()
To: Peter Zijlstra <peterz@infradead.org>,
        Dave Chinner <david@fromorbit.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>,
        linux-fsdevel@vger.kernel.org,
        Johannes Berg <johannes.berg@intel.com>,
        Ingo Molnar <mingo@redhat.com>, Theodore Ts'o <tytso@mit.edu>
References: <20181026164905.214474-1-bvanassche@acm.org>
 <20181027053745.GI6311@dastard>
 <20181028175840.GA744@hirez.programming.kicks-ass.net>
From: Bart Van Assche <bvanassche@acm.org>
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Date: Sun, 28 Oct 2018 13:45:27 -0700
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On 10/28/18 10:58 AM, Peter Zijlstra wrote:
> On Sat, Oct 27, 2018 at 04:37:45PM +1100, Dave Chinner wrote:
>> As an API, however, this needs to be consistent with
>> down_read_non_owner()/up_read_non_owner() which are for exactly this
>> same issue issue (different acquire/release contexts) on the read
>> side of the rwsem. Indeed, it can probably use the same
>> infrastructure...
> 
> Also, from a quick look, this has been broken for donkeys years,
> right?
Hi Peter,

If you are referring to the direct I/O code: the lockdep complaint shown 
in my patch description is new. I think the following commit from two 
months ago (which seems fine to me) made that lockdep complaint appear: 
87915adc3f0a ("workqueue: re-add lockdep dependencies for flushing").

Bart.