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shutdown: do not umount recursively before MS_MOVE

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Unmounting filesystem will be done gracefully by shutdown itself.

Follow-up for f2c1d491a539035d6cc1fa53a7cef0cbc8d52902 and
268d1244e87a35ff8dff56c92ef375ebf69d462e.

(cherry picked from commit 6b219b74de53729249956221a971047aab7c96e0)
This commit is contained in:
Yu Watanabe 2023-08-03 04:19:14 +09:00 committed by Zbigniew Jędrzejewski-Szmek
parent 60046bf2a9
commit c75ca56950
3 changed files with 10 additions and 6 deletions
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3
src/shared/switch-root.c
View File

@ -166,7 +166,8 @@ int switch_root(const char *new_root,
* MS_MOVE won't magically unmount anything below it. Once the chroot() succeeds the mounts
* below would still be around but invisible to us, because not accessible via
* /proc/self/mountinfo. Hence, let's clean everything up first, as long as we still can. */
(void) umount_recursive_full(NULL, MNT_DETACH, STRV_MAKE(new_root));
if (!FLAGS_SET(flags, SWITCH_ROOT_SKIP_RECURSIVE_UMOUNT))
(void) umount_recursive_full(NULL, MNT_DETACH, STRV_MAKE(new_root));
if (mount(".", "/", NULL, MS_MOVE, NULL) < 0)
return log_error_errno(errno, "Failed to move %s to /: %m", new_root);

8
src/shared/switch-root.h
View File

@ -4,9 +4,11 @@
#include <stdbool.h>
typedef enum SwitchRootFlags {
SWITCH_ROOT_DESTROY_OLD_ROOT = 1 << 0, /* rm -rf old root when switching – under the condition that it is backed by non-persistent tmpfs/ramfs/… */
SWITCH_ROOT_DONT_SYNC = 1 << 1, /* don't call sync() immediately before switching root */
SWITCH_ROOT_SKIP_RECURSIVE_RUN = 1 << 2, /* move /run without MS_REC */
SWITCH_ROOT_DESTROY_OLD_ROOT = 1 << 0, /* rm -rf old root when switching – under the condition
* that it is backed by non-persistent tmpfs/ramfs/… */
SWITCH_ROOT_DONT_SYNC = 1 << 1, /* don't call sync() immediately before switching root */
SWITCH_ROOT_SKIP_RECURSIVE_RUN = 1 << 2, /* move /run without MS_REC */
SWITCH_ROOT_SKIP_RECURSIVE_UMOUNT = 1 << 3, /* do not umount recursively on move */
} SwitchRootFlags;
int switch_root(const char *new_root, const char *old_root_after, SwitchRootFlags flags);

5
src/shutdown/shutdown.c
View File

@ -168,12 +168,13 @@ static int switch_root_initramfs(void) {
* Disable sync() during switch-root, we after all sync'ed here plenty, and a dumb sync (as opposed
* to the "smart" sync() we did here that looks at progress parameters) would defeat much of our
* efforts here. As the new root will be /run/initramfs/, it is not necessary to mount /run/
* recursively. */
* recursively. Also, do not umount filesystems before MS_MOVE, as that should be done by ourself. */
return switch_root(
/* new_root= */ "/run/initramfs",
/* old_root_after= */ "/oldroot",
/* flags= */ SWITCH_ROOT_DONT_SYNC |
SWITCH_ROOT_SKIP_RECURSIVE_RUN);
SWITCH_ROOT_SKIP_RECURSIVE_RUN |
SWITCH_ROOT_SKIP_RECURSIVE_UMOUNT);
}
/* Read the following fields from /proc/meminfo: