commit: 087ffecdaa1875cc683a7a5bc0695b3ebfce3bad
From: Roger Pau Monne <[email protected]>
Date: Thu, 14 Feb 2013 11:12:09 +0100
Subject: xen-blkback: use balloon pages for persistent grants
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With current persistent grants implementation we are not freeing the
persistent grants after we disconnect the device. Since grant map
operations change the mfn of the allocated page, and we can no longer
pass it to __free_page without setting the mfn to a sane value, use
balloon grant pages instead, as the gntdev device does.

Signed-off-by: Roger Pau Monné <[email protected]>
Cc: [email protected]
Cc: Konrad Rzeszutek Wilk <[email protected]>
Signed-off-by: Konrad Rzeszutek Wilk <[email protected]>
---
 drivers/block/xen-blkback/blkback.c |    6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/block/xen-blkback/blkback.c 
b/drivers/block/xen-blkback/blkback.c
index 1966a7c..de1f319 100644
--- a/drivers/block/xen-blkback/blkback.c
+++ b/drivers/block/xen-blkback/blkback.c
@@ -46,6 +46,7 @@
 #include <xen/xen.h>
 #include <asm/xen/hypervisor.h>
 #include <asm/xen/hypercall.h>
+#include <xen/balloon.h>
 #include "common.h"
 
 /*
@@ -239,6 +240,7 @@ static void free_persistent_gnts(struct rb_root *root, 
unsigned int num)
                        ret = gnttab_unmap_refs(unmap, NULL, pages,
                                segs_to_unmap);
                        BUG_ON(ret);
+                       free_xenballooned_pages(segs_to_unmap, pages);
                        segs_to_unmap = 0;
                }
 
@@ -527,8 +529,8 @@ static int xen_blkbk_map(struct blkif_request *req,
                                GFP_KERNEL);
                        if (!persistent_gnt)
                                return -ENOMEM;
-                       persistent_gnt->page = alloc_page(GFP_KERNEL);
-                       if (!persistent_gnt->page) {
+                       if (alloc_xenballooned_pages(1, &persistent_gnt->page,
+                           false)) {
                                kfree(persistent_gnt);
                                return -ENOMEM;
                        }
-- 
1.7.10.4
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