[Xen-changelog] [xen-unstable] hotplug scripts: better same_vm checks

[Xen patchbot-unstable <patchbot-unstable@xxxxxxxxxxxxxxxxxxx>]

# HG changeset patch
# User Keir Fraser <keir.fraser@xxxxxxxxxx>
# Date 1250683893 -3600
# Node ID c0576bd2ddfdfc7d6334b971490adfea60f6ee9f
# Parent  23678c44c3d348e538506eaf636af43fd9d7b2ff
hotplug scripts: better same_vm checks

currently the function same_vm in block-common.sh is the one
responsible for detecting if two block devices can be used at the same
time by two VMs. This can be allowed in few specific cases: when the
two VMs are actually the same VM and when the two VMs are the guest
and its stubdomain. We need to expand these exceptions to handle
properly save restore issues: this patch adds to the exceptions the
case when two VMs are the same VM because of save\restore races, and
when two VMs are the guest and the stubdomain of the previous guest,
again during save\restore.

Signed-off-by: Stefano Stabellini <stefano.stabellini@xxxxxxxxxxxxx>
---
 tools/hotplug/Linux/block-common.sh |   10 +++++++++-
 1 files changed, 9 insertions(+), 1 deletion(-)

diff -r 23678c44c3d3 -r c0576bd2ddfd tools/hotplug/Linux/block-common.sh
--- a/tools/hotplug/Linux/block-common.sh       Wed Aug 19 13:02:31 2009 +0100
+++ b/tools/hotplug/Linux/block-common.sh       Wed Aug 19 13:11:33 2009 +0100
@@ -112,6 +112,14 @@ same_vm()
                   "$FRONTEND_UUID")
   local target=$(xenstore_read_default  "/local/domain/$FRONTEND_ID/target"   \
                  "-1")
-  [ "$FRONTEND_UUID" = "$othervm" -o "$target" = "$otherdom" ]
+  local otarget=$(xenstore_read_default  "/local/domain/$otherdom/target"   \
+                 "-1")
+  local otvm=$(xenstore_read_default  "/local/domain/$otarget/vm"   \
+                 "-1")
+  otvm=${otvm%-1}
+  othervm=${othervm%-1}
+  local frontend_uuid=${FRONTEND_UUID%-1}
+  
+  [ "$frontend_uuid" = "$othervm" -o "$target" = "$otherdom" -o 
"$frontend_uuid" = "$otvm" ]
 }
 

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