From mboxrd@z Thu Jan  1 00:00:00 1970
From: Al Viro <viro@ZenIV.linux.org.uk>
Subject: Re: [PATCH] Fix mountpoint reference leakage in linkat
Date: Fri, 31 Jan 2014 22:30:14 +0000
Message-ID: <20140131223013.GP10323@ZenIV.linux.org.uk>
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 <20140131163231.2585a08d@tlielax.poochiereds.net>
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Cc: Oleg Drokin <green@linuxhacker.ru>, linux-kernel@vger.kernel.org,
	linux-fsdevel@vger.kernel.org
To: Jeff Layton <jlayton@redhat.com>
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On Fri, Jan 31, 2014 at 04:32:31PM -0500, Jeff Layton wrote:

>  	done_path_create(&new_path, new_dentry);
> +	path_put(&old_path);

... and the filesystem in question isn't pinned anymore, so it can be
unmounted, except that

>  	if (delegated_inode) {
>  		error = break_deleg_wait(&delegated_inode);

this does an iput() on delegated_inode.  And umount really doesn't
like finding pinned inodes.  Sorry, no go.

I'm going with Oleg's patch with second path_put() added.