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Date: Thu, 19 Apr 2018 01:15:59 +0100
From: Al Viro <viro@ZenIV.linux.org.uk>
To: Eric Biggers <ebiggers3@gmail.com>
Cc: linux-btrfs@vger.kernel.org, Chris Mason <clm@fb.com>,
        linux-fsdevel@vger.kernel.org
Subject: Re: d_instantiate() and unlock_new_inode() order in btrfs_mkdir()
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References: <20180419000029.GA133757@gmail.com>
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On Thu, Apr 19, 2018 at 01:06:13AM +0100, Al Viro wrote:
> On Wed, Apr 18, 2018 at 05:00:29PM -0700, Eric Biggers wrote:
> > Hi Chris and other btrfs folks,
> > 
> > btrfs_mkdir() calls d_instantiate() before unlock_new_inode(), which is wrong
> > because it exposes the inode to lookups before it's been fully initialized.
> 
> Huh?  It *is* fully initialized by that point; what else is left to do?

	ISTR something about false positives from lockdep (with
lockdep_annotate_inode_mutex_key() called too late, perhaps?); said that, it
was a long time ago and I don't remember details at the moment...  Are you
actually seeing a deadlock there or is that just lockdep complaining?