From 93bd157722c76b47d80742f290373c1ce2865070 Mon Sep 17 00:00:00 2001 From: Lennart Poettering 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); -- 1.7.10.4