libxl: correctly parse storage devices on driver domains

Don't try to check physical devices if they belong to a domain
different than the one where the toolstack is running. This prevents
the following error when trying to use storage driver domains:

libxl: debug: libxl_create.c:1246:do_domain_create: ao 0x1819240: create: how=(nil) callback=(nil) poller=0x1818fa0
libxl: debug: libxl_device.c:235:libxl__device_disk_set_backend: Disk vdev=xvda spec.backend=phy
libxl: debug: libxl_device.c:175:disk_try_backend: Disk vdev=xvda, backend phy unsuitable as phys path not a block device
libxl: error: libxl_device.c:278:libxl__device_disk_set_backend: no suitable backend for disk xvda

Signed-off-by: Roger Pau Monné <roger.pau@citrix.com>
Acked-by: Ian Jackson <ian.jackson@eu.citrix.com>

diff --git a/tools/libxl/libxl_device.c b/tools/libxl/libxl_device.c
index a5cf446a242a0a9ec77083d8fed139338043600a..b1fc4efe03f53508a16d43eb5bdf8c223d322007 100644 (file)
--- a/tools/libxl/libxl_device.c
+++ b/tools/libxl/libxl_device.c
@@ -161,6 +161,12 @@ static int disk_try_backend(disk_try_backend_args *a,
             goto bad_format;
         }
 
+        if (a->disk->backend_domid != LIBXL_TOOLSTACK_DOMID) {
+            LOG(DEBUG, "Disk vdev=%s, is using a storage driver domain, "
+                       "skipping physical device check", a->disk->vdev);
+            return backend;
+        }
+
         if (a->disk->script) {
             LOG(DEBUG, "Disk vdev=%s, uses script=... assuming phy backend",
                 a->disk->vdev);