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Merge pull request #28648 from yuwata/shutdown-skip-recursive-mount-run

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shutdown: several fixlets
This commit is contained in:
Mike Yuan 2023-08-04 12:45:32 +08:00 committed by GitHub
commit 07bd7b3868
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3 changed files with 24 additions and 6 deletions
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15
src/shared/switch-root.c
View File

@ -76,6 +76,18 @@ int switch_root(const char *new_root,
r = fd_make_mount_point(new_root_fd);
if (r < 0)
return log_error_errno(r, "Failed to make new root directory a mount point: %m");
if (r > 0) {
int fd;
/* When the path was not a mount point, then we need to reopen the path, otherwise, it still
* points to the underlying directory. */
fd = open(new_root, O_DIRECTORY|O_CLOEXEC);
if (fd < 0)
return log_error_errno(errno, "Failed to reopen target directory '%s': %m", new_root);
close_and_replace(new_root_fd, fd);
}
if (FLAGS_SET(flags, SWITCH_ROOT_DESTROY_OLD_ROOT)) {
istmp = fd_is_temporary_fs(old_root_fd);
@ -166,7 +178,8 @@ 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);

7
src/shutdown/shutdown.c
View File

@ -167,11 +167,14 @@ 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. */
* efforts here. As the new root will be /run/initramfs/, it is not necessary to mount /run/
* 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);
/* flags= */ SWITCH_ROOT_DONT_SYNC |
SWITCH_ROOT_SKIP_RECURSIVE_RUN |
SWITCH_ROOT_SKIP_RECURSIVE_UMOUNT);
}
/* Read the following fields from /proc/meminfo: