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Date: Wed, 19 Jan 2011 14:27:24 -0800
Message-ID: <AANLkTinVP=OuJ-3u9pHdDuuKJoVrP4Unr5Dx1x=qHtXC@mail.gmail.com>
Subject: Re: [PATCH 17/46] fs: Use rename lock and RCU for multi-step operations
From: Yehuda Sadeh Weinraub <yehudasa@gmail.com>
To: Nick Piggin <npiggin@gmail.com>
Cc: Nick Piggin <npiggin@kernel.dk>, linux-fsdevel@vger.kernel.org,
        linux-kernel@vger.kernel.org, Sage Weil <sage@newdream.net>,
        ceph-devel@vger.kernel.org
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On Tue, Jan 18, 2011 at 2:42 PM, Nick Piggin <npiggin@gmail.com> wrote:
> On Wed, Jan 19, 2011 at 9:32 AM, Yehuda Sadeh Weinraub

>> There's an issue with ceph as it references the
>> dentry->d_parent(->d_inode) at dentry_release(), so setting
>> dentry->d_parent to NULL here doesn't work with ceph. Though there is
>> some workaround for it, we would like to be sure that this one is
>> really required so that we don't exacerbate the ugliness. The
>> workaround is to keep a pointer to the parent inode in the private
>> dentry structure, which will be referenced only at the .release()
>> callback. This is clearly not ideal.
>
> Hmm, I'll have to think about it. Probably we can check for
> d_count == 0 rather than parent != NULL I think?
>

That'll solve ceph's problem, don't know about how'd affect other
stuff. We'll need to know whether this is the solution, or whether
we'd need to introduce some other band aid fix.

Thanks,
Yehuda