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Date: Sun, 28 Oct 2018 18:58:40 +0100
From: Peter Zijlstra <peterz@infradead.org>
To: Dave Chinner <david@fromorbit.com>
Cc: Bart Van Assche <bvanassche@acm.org>,
        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>
Subject: Re: [PATCH RFC] kernel/locking, fs/direct-io: Introduce and use
 down_write_nolockdep()
Message-ID: <20181028175840.GA744@hirez.programming.kicks-ass.net>
References: <20181026164905.214474-1-bvanassche@acm.org>
 <20181027053745.GI6311@dastard>
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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...

Indeed.

Also, from a quick look, this has been broken for donkeys years,
right? That comment:

	/* will be released by direct_io_worker */

has been there since 2009. Back then of course it was a mutex, and the
curious thing is, mutexes have _never_ supported this release from
another context thing.

Colour me confused.