qvm-template-postprocess: fix installing templates with small rootfs

There is already support for importing volume of a specific size, no
need for calling resize manually. This fixes template install on storage
pools that do not support resize (shrinking).

Fixes QubesOS/qubes-issues#7426

qubesadmin/tests/tools/qvm_template_postprocess.py

@@ -58,24 +58,10 @@ def test_000_import_root_img_raw(self):
         self.app.expected_calls[('test-vm', 'admin.vm.volume.List', None,
                 None)] = \
             b'0\0root\nprivate\nvolatile\nkernel\n'
-        self.app.expected_calls[
-            ('test-vm', 'admin.vm.volume.Info', 'root', None)] = \
-            b'0\x00pool=lvm\n' \
-            b'vid=qubes_dom0/vm-test-vm-root\n' \
-            b'size=10737418240\n' \
-            b'usage=0\n' \
-            b'rw=True\n' \
-            b'source=\n' \
-            b'save_on_stop=True\n' \
-            b'snap_on_start=False\n' \
-            b'revisions_to_keep=3\n' \
-            b'is_outdated=False\n'
-        self.app.expected_calls[('test-vm', 'admin.vm.volume.Resize', 'root',
-                str(len(volume_data)).encode())] = \
-            b'0\0'
 
-        self.app.expected_calls[('test-vm', 'admin.vm.volume.Import', 'root',
-            volume_data)] = b'0\0'
+        self.app.expected_calls[(
+            'test-vm', 'admin.vm.volume.ImportWithSize', 'root',
+            str(len(volume_data)).encode() + b'\n' + volume_data)] = b'0\0'
         vm = self.app.domains['test-vm']
         qubesadmin.tools.qvm_template_postprocess.import_root_img(
             vm, self.source_dir.name)
@@ -95,27 +81,13 @@ def test_001_import_root_img_tar(self):
 
         self.app.expected_calls[('dom0', 'admin.vm.List', None, None)] = \
             b'0\0test-vm class=TemplateVM state=Halted\n'
-        self.app.expected_calls[
-            ('test-vm', 'admin.vm.volume.Info', 'root', None)] = \
-            b'0\x00pool=lvm\n' \
-            b'vid=qubes_dom0/vm-test-vm-root\n' \
-            b'size=10737418240\n' \
-            b'usage=0\n' \
-            b'rw=True\n' \
-            b'source=\n' \
-            b'save_on_stop=True\n' \
-            b'snap_on_start=False\n' \
-            b'revisions_to_keep=3\n' \
-            b'is_outdated=False\n'
         self.app.expected_calls[('test-vm', 'admin.vm.volume.List', None,
                 None)] = \
             b'0\0root\nprivate\nvolatile\nkernel\n'
-        self.app.expected_calls[('test-vm', 'admin.vm.volume.Resize', 'root',
-                str(len(volume_data)).encode())] = \
-            b'0\0'
 
-        self.app.expected_calls[('test-vm', 'admin.vm.volume.Import', 'root',
-            volume_data)] = b'0\0'
+        self.app.expected_calls[(
+            'test-vm', 'admin.vm.volume.ImportWithSize', 'root',
+            str(len(volume_data)).encode() + b'\n' + volume_data)] = b'0\0'
         vm = self.app.domains['test-vm']
         qubesadmin.tools.qvm_template_postprocess.import_root_img(
             vm, self.source_dir.name)

qubesadmin/tools/qvm_template_postprocess.py

@@ -94,8 +94,6 @@ def import_root_img(vm, source_dir):
     #  volume needs to be extended, do it before import, if reduced - after.
 
     root_size = get_root_img_size(source_dir)
-    if vm.volumes['root'].size < root_size:
-        vm.volumes['root'].resize(root_size)
 
     root_path = os.path.join(source_dir, 'root.img')
     if os.path.exists(root_path + '.part.00'):
@@ -106,7 +104,8 @@ def import_root_img(vm, source_dir):
                     stdin=cat.stdout,
                     stdout=subprocess.PIPE) as tar:
                 cat.stdout.close()
-                vm.volumes['root'].import_data(stream=tar.stdout)
+                vm.volumes['root'].import_data_with_size(
+                    stream=tar.stdout, size=root_size)
         if tar.returncode != 0:
             raise qubesadmin.exc.QubesException(
                 'root.img extraction failed')
@@ -116,7 +115,8 @@ def import_root_img(vm, source_dir):
     elif os.path.exists(root_path + '.tar'):
         with subprocess.Popen(['tar', 'xSOf', root_path + '.tar'],
                 stdout=subprocess.PIPE) as tar:
-            vm.volumes['root'].import_data(stream=tar.stdout)
+            vm.volumes['root'].import_data_with_size(
+                stream=tar.stdout, size=root_size)
         if tar.returncode != 0:
             raise qubesadmin.exc.QubesException('root.img extraction failed')
     elif os.path.exists(root_path):
@@ -131,16 +131,8 @@ def import_root_img(vm, source_dir):
                 vm.log.info('root.img already in place, do not re-import')
                 return
         with open(root_path, 'rb') as root_file:
-            vm.volumes['root'].import_data(stream=root_file)
-
-    if vm.volumes['root'].size > root_size:
-        try:
-            vm.volumes['root'].resize(root_size)
-        except qubesadmin.exc.QubesException as err:
-            vm.log.warning(
-                'Failed to resize root volume of {} from {} to {} after '
-                'import: {}'.format(vm.name, vm.volumes['root'].size,
-                    root_size, str(err)))
+            vm.volumes['root'].import_data_with_size(
+                stream=root_file, size=root_size)
 
 
 def reset_private_img(vm):