switch-root: sync() before MNT_DETACH unmounting all old mounts

As discussed here:

https://github.com/systemd/systemd/pull/27670#discussion_r1196716794
This commit is contained in:
Lennart Poettering 2023-05-19 14:22:14 +02:00
parent b7106af465
commit 5221b55bb3

View file

@ -63,6 +63,13 @@ int switch_root(const char *new_root,
(void) mkdir_p_label(resolved_old_root_after, 0755);
}
/* We are about to unmount various file systems with MNT_DETACH (either explicitly via umount() or
* indirectly via pivot_root()), and thus do not synchronously wait for them to be fully sync'ed
* all while making them invisible/inaccessible in the file system tree for later code. That makes
* sync'ing them then difficult. Let's hence issue a manual sync() here, so that we at least can
* guarantee all file systems are an a good state before entering this state. */
sync();
/* Work-around for kernel design: the kernel refuses MS_MOVE if any file systems are mounted
* MS_SHARED. Hence remount them MS_PRIVATE here as a work-around.
*