From mboxrd@z Thu Jan  1 00:00:00 1970
From: Al Viro <viro@ZenIV.linux.org.uk>
Subject: Re: "don't bugger nd->seq" seems to break umount
	sometimes
Date: Wed, 29 Apr 2015 13:21:39 +0100
Message-ID: <20150429122139.GN889@ZenIV.linux.org.uk>
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	<21824.50281.405589.957467@mariner.uk.xensource.com>
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To: Ian Jackson <Ian.Jackson@eu.citrix.com>
Cc: xen-tools@packages.debian.org, xen-devel@lists.xensource.com, Andrew Cooper <andrew.cooper3@citrix.com>, stefano.stabellini@eu.citrix.com, Zefan Li <lizefan@huawei.com>, David Vrabel <david.vrabel@citrix.com>, Boris Ostrovsky <boris.ostrovsky@oracle.com>
List-Id: xen-devel@lists.xenproject.org

On Wed, Apr 29, 2015 at 12:45:45PM +0100, Ian Jackson wrote:

> The symptoms are that `umount' fails with EBUSY,

    [lizf: Backported to 3.4:
     - remove the changes to follow_link() as it doesn't call set_root()]

looks dubious - I don't have -stable in front of me, but set_root() in
follow_link() had migrated from __vfs_follow_link(), so could you try
(tr '#' '\t' | ed fs/namei.c) <<'EOF'
/__vfs_follow_link/
/set_root/s/^/#/
i
##if (!nd->root.mnt)
.
wq
EOF
and see if it helps?