From 93bd157722c76b47d80742f290373c1ce2865070 Mon Sep 17 00:00:00 2001

From: Lennart Poettering <lennart@poettering.net>

Date: Fri, 16 Nov 2012 18:36:28 +0100

Subject: [PATCH] umount: always remount read-only before unmounting in final

 shutdown loop

---

 src/core/umount.c | 57 ++++++++++++++++++++++++++-----------------------------

 1 file changed, 27 insertions(+), 30 deletions(-)

diff --git a/src/core/umount.c b/src/core/umount.c

index 83c9de3..e794057 100644

--- a/src/core/umount.c

+++ b/src/core/umount.c

@@ -407,6 +407,33 @@ static int mount_points_list_umount(MountPoint **head, bool *changed, bool log_e

         assert(head);

         LIST_FOREACH_SAFE(mount_point, m, n, *head) {

+

+                /* If we are in a container, don't attempt to

+                   read-only mount anything as that brings no real

+                   benefits, but might confuse the host, as we remount

+                   the superblock here, not the bind mound. */

+                if (detect_container(NULL) <= 0)  {

+                        /* We always try to remount directories

+                         * read-only first, before we go on and umount

+                         * them.

+                         *

+                         * Mount points can be stacked. If a mount

+                         * point is stacked below / or /usr, we

+                         * cannnot umount or remount it directly,

+                         * since there is no way to refer to the

+                         * underlying mount. There's nothing we can do

+                         * about it for the general case, but we can

+                         * do something about it if it is aliased

+                         * somehwere else via a bind mount. If we

+                         * explicitly remount the super block of that

+                         * alias read-only we hence should be

+                         * relatively safe regarding keeping the fs we

+                         * can otherwise not see dirty. */

+                        mount(NULL, m->path, NULL, MS_REMOUNT|MS_RDONLY, NULL);

+                }

+

+                /* Skip / and /usr since we cannot unmount that

+                 * anyway, since we are running from it */

                 if (path_equal(m->path, "/")

 #ifndef HAVE_SPLIT_USR

                     || path_equal(m->path, "/usr")

@@ -432,29 +459,6 @@ static int mount_points_list_umount(MountPoint **head, bool *changed, bool log_e

         return n_failed;

 }

-static int mount_points_list_remount_read_only(MountPoint **head, bool *changed) {

-        MountPoint *m, *n;

-        int n_failed = 0;

-

-        assert(head);

-

-        LIST_FOREACH_SAFE(mount_point, m, n, *head) {

-

-                /* Trying to remount read-only */

-                if (mount(NULL, m->path, NULL, MS_REMOUNT|MS_RDONLY, NULL) == 0) {

-                        if (changed)

-                                *changed = true;

-

-                        mount_point_free(head, m);

-                } else {

-                        log_warning("Could not remount as read-only %s: %m", m->path);

-                        n_failed++;

-                }

-        }

-

-        return n_failed;

-}

-

 static int swap_points_list_off(MountPoint **head, bool *changed) {

         MountPoint *m, *n;

         int n_failed = 0;

@@ -571,13 +575,6 @@ int umount_all(bool *changed) {

         if (r <= 0)

                 goto end;

-        /* If we are in a container, don't attempt to read-only mount

-           anything as that brings no real benefits, but might confuse

-           the host, as we remount the superblock here, not the bind

-           mound. */

-        if (detect_container(NULL) <= 0)

-                r = mount_points_list_remount_read_only(&mp_list_head, changed);

-

   end:

         mount_points_list_free(&mp_list_head);

-- 

1.7.12.1