Re: [PATCH] xen-blkback: use balloon pages for persistent grants

["Roger Pau Monné" <roger.pau@citrix.com>]

On 14/02/13 11:12, Roger Pau Monne wrote:
> 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 <roger.pau@citrix.com>
> Cc: xen-devel@lists.xen.org
> Cc: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>

I think this patch is missing the following change in Kconfig, but 
gntdev doesn't depend on the balloon driver, which it also uses, so I'm 
not sure.

---
diff --git a/drivers/block/Kconfig b/drivers/block/Kconfig
index f529407..74e2415 100644
--- a/drivers/block/Kconfig
+++ b/drivers/block/Kconfig
@@ -488,7 +488,7 @@ config XEN_BLKDEV_FRONTEND
 
 config XEN_BLKDEV_BACKEND
 	tristate "Xen block-device backend driver"
-	depends on XEN_BACKEND
+	depends on XEN_BACKEND && XEN_BALLOON
 	help
 	  The block-device backend driver allows the kernel to export its
 	  block devices to other guests via a high-performance shared-memory