libxl: include domain id in userdata path.

The userdata is specific to a particular incarnation of a domain and
the patch is therefor required to be unique to each incarnation. If
the user has explicitly configured a UUID in their domain
configuration then the path is no longer unique since
22124:22366e13f76d "xl: randomly generate UUIDs" which (correctly)
caused the uuid domain configuration option to be obeyed.

If userdata is not unique to each incarnation of a domain then
localhost live migration is broken because the target is created (and
writes its userdata) before the sender destroys the domain (and
deletes its userdata).

Strictly speaking I think the UUID is unnecessary but it is perhaps
helpful to people looking in the userdata directory, for debugging
etc.

Signed-off-by: Ian Campbell <ian.campbell@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>
Signed-off-by: Ian Jackson <ian.jackson@eu.citrix.com>

diff --git a/tools/libxl/libxl_dom.c b/tools/libxl/libxl_dom.c
index e83bbbf20b844355406f5262ebd669050104cc9c..d9781e7060f20a07032cccec3f6bbfa8e8cb0584 100644 (file)
--- a/tools/libxl/libxl_dom.c
+++ b/tools/libxl/libxl_dom.c
@@ -466,8 +466,8 @@ static const char *userdata_path(libxl_gc *gc, uint32_t domid,
     uuid_string = libxl_sprintf(gc, LIBXL_UUID_FMT, LIBXL_UUID_BYTES(info.uuid));
 
     path = libxl_sprintf(gc, "/var/lib/xen/"
-                         "userdata-%s.%s.%s",
-                         wh, uuid_string, userdata_userid);
+                         "userdata-%s.%u.%s.%s",
+                         wh, domid, uuid_string, userdata_userid);
     if (!path)
         XL_LOG_ERRNO(ctx, XL_LOG_ERROR, "unable to allocate for"
                      " userdata path");