From c43cf3ea838541ea9f066f4f1aa7b197cba6276e Mon Sep 17 00:00:00 2001
From: Jennifer Herbert <jennifer.herbert@citrix.com>
Date: Mon, 5 Jan 2015 16:49:22 +0000
Subject: [PATCH] xen-blkback: safely unmap grants in case they are still in
 use
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Use gnttab_unmap_refs_async() to wait until the mapped pages are no
longer in use before unmapping them.

This allows blkback to use network storage which may retain refs to
pages in queued skbs after the block I/O has completed.

Signed-off-by: Jennifer Herbert <jennifer.herbert@citrix.com>
Acked-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Jens Axboe <axboe@kernel.de>
Signed-off-by: David Vrabel <david.vrabel@citrix.com>
---
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