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Date: Thu, 10 Nov 2016 23:05:57 +0000
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Amir Goldstein <amir73il@gmail.com>
Cc: Miklos Szeredi <miklos@szeredi.hu>,
        Konstantin Khlebnikov <koct9i@gmail.com>,
        linux-unionfs@vger.kernel.org, linux-fsdevel@vger.kernel.org
Subject: Re: [RFC][PATH 4/4] ovl: relax lock_rename when moving files between
 work and upper dir
Message-ID: <20161110230557.GM19539@ZenIV.linux.org.uk>
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On Thu, Nov 10, 2016 at 11:02:21PM +0000, Al Viro wrote:
> On Fri, Nov 11, 2016 at 12:44:43AM +0200, Amir Goldstein wrote:
> > If work dir and upper dir have a common parent, then it
> > is safe to move files between them without taking the super block
> > s_vfs_rename_mutex.
> > 
> > Since both upper dir and work dir (as well as $workdir/work)
> > are delete locked on overlay mount, they cannot be moved.
> 
> Do explain.  What do you mean, "delete locked" and why exactly can't they
> be moved?

More specifically, what makes you think that may_delete() is called before
any change of parent?