fix resize of unpartitioned images with libguestfs

Following on from I9c974e138ff90e8b7a5a40f5b31dcdb25a59622d
Ensure that the libguestfs path also throws a NovaException,
handled by can_resize_fs().

* nova/virt/disk/vfs/guestfs.py (setup): Move the debug message
and guestfs handle outside the exception handler as we
don't want to map failure of those to a NovaException
that indicates an issue with the image as opposed to the
nova code or libguestfs installation.  Change to a more explicit
exception thrown by guestfs, so as to avoid masking other issues.
(teardown): Remove redundant calls to str().
* nova/virt/disk/api.py (can_resize_fs): Cleanup the debug messages,
and use the newer vfs API directly, rather than the slightly
hacky call to inject_data() with no data to inject.

Fixes bug: 1094373
Change-Id: I3e1305cf6bb64278a8caf37e4c5005cb9683f632

2 files changed, 20 insertions, 13 deletions

diff --git a/nova/virt/disk/api.py b/nova/virt/disk/api.py
index f663515cd..a93cf261e 100644
--- a/nova/virt/disk/api.py
+++ b/nova/virt/disk/api.py
@@ -124,6 +124,9 @@ def extend(image, size):
 def can_resize_fs(image, size, use_cow=False):
     """Check whether we can resize contained file system."""
 
+    LOG.debug(_('Checking if we can resize image %(image)s. '
+                'size=%(size)s, CoW=%(use_cow)s'), locals())
+
     # Check that we're increasing the size
     virt_size = get_disk_size(image)
     if virt_size >= size:
@@ -133,19 +136,18 @@ def can_resize_fs(image, size, use_cow=False):
 
     # Check the image is unpartitioned
     if use_cow:
-        # Try to mount an unpartitioned qcow2 image
-        LOG.debug(_('Checking if we can resize the COW image %s.'), image)
         try:
-            inject_data(image, use_cow=True)
+            fs = vfs.VFS.instance_for_image(image, 'qcow2', None)
+            fs.setup()
+            fs.teardown()
         except exception.NovaException, e:
-            LOG.debug(_('File injection failed for image %(image)s with '
+            LOG.debug(_('Unable to mount image %(image)s with '
                         'error %(error)s. Cannot resize.'),
                       {'image': image,
                        'error': e})
             return False
     else:
         # For raw, we can directly inspect the file system
-        LOG.debug(_('Checking if we can resize the non-COW image %s.'), image)
         try:
             utils.execute('e2label', image)
         except exception.ProcessExecutionError, e:
diff --git a/nova/virt/disk/vfs/guestfs.py b/nova/virt/disk/vfs/guestfs.py
index 5fe599b89..66c6849d4 100644
--- a/nova/virt/disk/vfs/guestfs.py
+++ b/nova/virt/disk/vfs/guestfs.py
@@ -89,18 +89,23 @@ class VFSGuestFS(vfs.VFS):
             self.handle.mount_options("", mount[1], mount[0])
 
     def setup(self):
-        try:
-            LOG.debug(_("Setting up appliance for %(imgfile)s %(imgfmt)s") %
-                      {'imgfile': self.imgfile, 'imgfmt': self.imgfmt})
-            self.handle = guestfs.GuestFS()
+        LOG.debug(_("Setting up appliance for %(imgfile)s %(imgfmt)s") %
+                  {'imgfile': self.imgfile, 'imgfmt': self.imgfmt})
+        self.handle = guestfs.GuestFS()
 
+        try:
             self.handle.add_drive_opts(self.imgfile, format=self.imgfmt)
             self.handle.launch()
 
             self.setup_os()
 
             self.handle.aug_init("/", 0)
-        except Exception, e:
+        except RuntimeError, e:
+            self.handle = None
+            raise exception.NovaException(
+                _("Error mounting %(imgfile)s with libguestfs (%(e)s)") %
+                {'imgfile': self.imgfile, 'e': e})
+        except Exception:
             self.handle = None
             raise
 
@@ -109,15 +114,15 @@ class VFSGuestFS(vfs.VFS):
         try:
             self.handle.aug_close()
         except Exception, e:
-            LOG.debug(_("Failed to close augeas %s"), str(e))
+            LOG.debug(_("Failed to close augeas %s"), e)
         try:
             self.handle.shutdown()
         except Exception, e:
-            LOG.debug(_("Failed to shutdown appliance %s"), str(e))
+            LOG.debug(_("Failed to shutdown appliance %s"), e)
         try:
             self.handle.close()
         except Exception, e:
-            LOG.debug(_("Failed to close guest handle %s"), str(e))
+            LOG.debug(_("Failed to close guest handle %s"), e)
         self.handle = None
 
     @staticmethod