Based on d677d4df80e0ea1c66c691f50867fedd63c6770a Mon Sep 17 00:00:00 2001
From: =?UTF-8?q?Zbigniew=20J=C4=99drzejewski-Szmek?= <zbyszek@in.waw.pl>
Date: Thu, 16 Oct 2014 19:12:55 -0500
Subject: [PATCH] systemd: continue switch-root even if umount fails

Leaving the old root around seems better than aborting the
switch.
---
 src/core/main.c        |    2 +-
 src/core/switch-root.c |   11 +++++------
 2 files changed, 6 insertions(+), 7 deletions(-)

--- src/core/main.c
+++ src/core/main.c	2014-10-20 13:35:35.915837828 +0000
@@ -1848,7 +1848,7 @@ finish:
                         /* And switch root */
                         r = switch_root(switch_root_dir);
                         if (r < 0)
-                                log_error("Failed to switch root, ignoring: %s", strerror(-r));
+                                log_error("Failed to switch root, trying to continue: %s", strerror(-r));
                 }
 
                 args_size = MAX(6, argc+1);
--- src/core/switch-root.c
+++ src/core/switch-root.c	2014-10-20 13:39:58.167121460 +0000
@@ -68,10 +68,9 @@ int switch_root(const char *new_root) {
                 goto fail;
         }
 
-        /* Work-around for a kernel bug: for some reason the kernel
-         * refuses switching root if any file systems are mounted
-         * MS_SHARED. Hence remount them MS_PRIVATE here as a
-         * work-around.
+        /* Work-around for kernel design: the kernel refuses switching
+         * root if any file systems are mounted MS_SHARED. Hence
+         * remount them MS_PRIVATE here as a work-around.
          *
          * https://bugzilla.redhat.com/show_bug.cgi?id=847418 */
         if (mount(NULL, "/", NULL, MS_REC|MS_PRIVATE, NULL) < 0)
@@ -124,8 +123,8 @@ int switch_root(const char *new_root) {
                  * running off it we need to do this lazily. */
                 if (umount2("/mnt", MNT_DETACH) < 0) {
                         r = -errno;
-                        log_error("Failed to umount old root dir /mnt: %m");
-                        goto fail;
+                        log_error("Failed to lazily umount old root dir /mnt, %s: %m",
+                                  errno == ENOENT ? "ignoring" : "leaving it around");
                 }
 
         } else if (mount(new_root, "/", NULL, MS_MOVE, NULL) < 0) {
