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Date:   Thu, 1 Aug 2019 17:10:49 +0100
From:   Al Viro <viro@zeniv.linux.org.uk>
To:     Ondrej Mosnacek <omosnace@redhat.com>
Cc:     selinux@vger.kernel.org, Paul Moore <paul@paul-moore.com>,
        linux-fsdevel@vger.kernel.org
Subject: Re: [PATCH v2 1/4] d_walk: optionally lock also parent inode
Message-ID: <20190801161049.GX1131@ZenIV.linux.org.uk>
References: <20190801140243.24080-1-omosnace@redhat.com>
 <20190801140243.24080-2-omosnace@redhat.com>
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On Thu, Aug 01, 2019 at 04:02:40PM +0200, Ondrej Mosnacek wrote:
> @@ -1276,6 +1277,8 @@ static void d_walk(struct dentry *parent, void *data,
>  again:
>  	read_seqbegin_or_lock(&rename_lock, &seq);
>  	this_parent = parent;
> +	if (lock_inode)
> +		inode_lock(this_parent->d_inode);

Suppose we are on the second pass through that thing - with rename_lock held.
What will happen to that inode_lock?