From ec14875a8531be3a9b814066a7393513677d2182 Mon Sep 17 00:00:00 2001
From: Michael Hudson-Doyle <michael.hudson@canonical.com>
Date: Mon, 18 Nov 2019 14:27:31 +1300
Subject: [PATCH] if /target exists, run curtin umount /target before first
 disk probe

The installer now lets you restart after an install failure, but unless
we do something like this, the target system still being mounted will
make life confusing.

It's more robust to be defensive and try to unmount at startup rather
than trying to unmount before restarting.
---
 subiquity/controllers/filesystem.py | 25 ++++++++++++++++++++++---
 1 file changed, 22 insertions(+), 3 deletions(-)

diff --git a/subiquity/controllers/filesystem.py b/subiquity/controllers/filesystem.py
index add0c7c2..33c31a47 100644
--- a/subiquity/controllers/filesystem.py
+++ b/subiquity/controllers/filesystem.py
@@ -18,6 +18,7 @@ import json
 import logging
 import os
 import select
+import sys
 import time
 
 import pyudev
@@ -144,12 +145,29 @@ class FilesystemController(BaseController):
         self._probes = {}
 
     def start(self):
-        self._start_probe(restricted=False)
+        self._start_probe(restricted=False, start=False)
+        target = self.app.base_model.target
+        if os.path.exists(target):
+            self.run_in_bg(self._bg_unmount, self._unmounted)
+        else:
+            self._cur_probe.start()
+
+    def _bg_unmount(self):
+        cmd = [
+            sys.executable, '-m', 'curtin', 'unmount',
+            '-t', self.app.base_model.target,
+            ]
+        if self.opts.dry_run:
+            cmd = ['sleep', 0.2]
+        run_command(cmd)
+
+    def _unmounted(self, fut):
         context = pyudev.Context()
         self._monitor = pyudev.Monitor.from_netlink(context)
         self._monitor.filter_by(subsystem='block')
         self._monitor.enable_receiving()
         self.start_listening_udev()
+        self._cur_probe.start()
 
     def start_listening_udev(self):
         self._udev_listen_handle = self.loop.watch_file(
@@ -178,10 +196,11 @@ class FilesystemController(BaseController):
             log.debug("_udev_event %s %s", action, dev)
         self._start_probe(restricted=False)
 
-    def _start_probe(self, *, restricted=False):
+    def _start_probe(self, *, restricted, start=True):
         p = Probe(self, restricted, 5.0, self._probe_done)
         self._cur_probe = self._probes[restricted] = p
-        p.start()
+        if start:
+            p.start()
 
     def _probe_done(self, probe):
         if probe is not self._cur_probe: