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Date: Wed, 03 Aug 2011 15:53:44 +0100
From: "Jan Beulich" <jbeulich@novell.com>
To: <daniel.stodden@citrix.com>, <Ian.Campbell@eu.citrix.com>,
        <jaxboe@fusionio.com>, <annie.li@oracle.com>, <joe.jin@oracle.com>,
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Cc: <xen-devel@lists.xensource.com>, <greg.marsden@oracle.com>,
        <linux-kernel@vger.kernel.org>
Subject: Re: [Xen-devel] [PATCH 0/3] xen-blkback: refactor vbd
	 remove/disconnect.
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>>> Joe Jin 08/03/11 4:10 AM >>> 
>1. start guest with the latest kernel. 
>2. attach new block device by xm block-attach in Dom0 
>3. mount new disk in guest 
>4. execute xm block-detach to detach the block device in dom0 until timeout 
>5. try to unmount the disk in guest, umount hung. at here, any IOs to the 
>device will hang. 

A bogus sequence of operations - an operator in Dom0 shouldn't remove
a device that is still in use in a guest, except as an exceptionasl measure
(and then other bad behavior is to be expected). What's the use case?

Jan