btrfs: support resizing if root is mounted ro.

Resize of btrfs fails if the mount point for the file system we are trying
to resize, i.e. the root of the filesystem is read only. With this change
we use a known (currently snapper specific) rw location to work around a
flaw that blocks resizing of the ro filesystem.

LP: #1734787

1 files changed, 46 insertions, 0 deletions

diff --git a/cloudinit/tests/test_util.py b/cloudinit/tests/test_util.py
new file mode 100644
index 00000000..ba6bf699
--- /dev/null
+++ b/cloudinit/tests/test_util.py
@@ -0,0 +1,46 @@
+# This file is part of cloud-init. See LICENSE file for license information.
+
+"""Tests for cloudinit.util"""
+
+import logging
+
+import cloudinit.util as util
+
+from cloudinit.tests.helpers import CiTestCase, mock
+
+LOG = logging.getLogger(__name__)
+
+MOUNT_INFO = [
+    '68 0 8:3 / / ro,relatime shared:1 - btrfs /dev/sda1 ro,attr2,inode64',
+    '153 68 254:0 / /home rw,relatime shared:101 - xfs /dev/sda2 rw,attr2'
+]
+
+
+class TestUtil(CiTestCase):
+
+    def test_parse_mount_info_no_opts_no_arg(self):
+        result = util.parse_mount_info('/home', MOUNT_INFO, LOG)
+        self.assertEqual(('/dev/sda2', 'xfs', '/home'), result)
+
+    def test_parse_mount_info_no_opts_arg(self):
+        result = util.parse_mount_info('/home', MOUNT_INFO, LOG, False)
+        self.assertEqual(('/dev/sda2', 'xfs', '/home'), result)
+
+    def test_parse_mount_info_with_opts(self):
+        result = util.parse_mount_info('/', MOUNT_INFO, LOG, True)
+        self.assertEqual(
+            ('/dev/sda1', 'btrfs', '/', 'ro,relatime'),
+            result
+        )
+
+    @mock.patch('cloudinit.util.get_mount_info')
+    def test_mount_is_rw(self, m_mount_info):
+        m_mount_info.return_value = ('/dev/sda1', 'btrfs', '/', 'rw,relatime')
+        is_rw = util.mount_is_read_write('/')
+        self.assertEqual(is_rw, True)
+
+    @mock.patch('cloudinit.util.get_mount_info')
+    def test_mount_is_ro(self, m_mount_info):
+        m_mount_info.return_value = ('/dev/sda1', 'btrfs', '/', 'ro,relatime')
+        is_rw = util.mount_is_read_write('/')
+        self.assertEqual(is_rw, False)