From 7fd152f4b6ae4f3cf89e4b7a0383cc3c470772fc Mon Sep 17 00:00:00 2001
From: Daniel Stodden <daniel.stodden@citrix.com>
Date: Sat, 7 Aug 2010 18:45:12 +0200
Subject: [PATCH] blkfront: Fix blkfront backend switch race (bdev release)

We cannot read backend state within bdev operations, because it risks
grabbing the state change before xenbus gets to do it.

Fixed by tracking deferral with a frontend switch to Closing. State
exposure isn't strictly necessary, but the backends won't mind.

For a 'clean' deferral this seems actually a more decent protocol than
raising errors.

Signed-off-by: Daniel Stodden <daniel.stodden@citrix.com>
Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
Signed-off-by: Jens Axboe <jaxboe@fusionio.com>
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Reading git-format-patch failed